METHODS AND MATERIALS FOR IDENTIFYING METASTATIC MALIGNANT SKIN LESIONS AND TREATING SKIN CANCER
This document provides methods and materials for identifying metastatic malignant skin lesions (e.g., malignant pigmented skin lesions). For example, methods and materials for using quantitative PCR results and correction protocols to reduce the impact of basal keratinocyte contamination on the analysis of test sample results to identify metastatic malignant skin lesions are provided. This document also provides methods and materials for treating skin cancer. For example, methods and materials for identifying a mammal (e.g., a human) having a pre-metastatic skin lesion (e.g., pre-metastatic melanoma) and treating that mammal with pentamidine (4,4′-[pentane-1,5-diylbis(oxy)]dibenzenecarboximidamide) are provided.
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This application claims the benefit of U.S. Provisional Ser. No. 62/037,325, filed Aug. 14, 2014, and U.S. Provisional Ser. No. 62/142,831, filed Apr. 3, 2015. This disclosure of the prior applications are considered part of (and are incorporated by reference in) the disclosure of this application.
BACKGROUND1. Technical Field
This document relates to methods and materials for identifying metastatic malignant skin lesions (e.g., metastatic malignant pigmented skin lesions). For example, this document relates to methods and materials for using quantitative PCR results and correction protocols to reduce the impact of basal keratinocyte contamination on the analysis of test sample results to identify metastatic malignant skin lesions. This document also relates to methods and materials for treating skin cancer. For example, this document relates to methods and materials for identifying a mammal (e.g., a human) having a pre-metastatic skin lesion (e.g., pre-metastatic melanoma) and treating that mammal with pentamidine (4,4′-[pentane-1,5-diylbis(oxy)]dibenzenecarboximidamide).
2. Background Information
Malignant skin lesions are typically identified by obtaining a skin biopsy and morphologically assessing the biopsy's melanocytes under a microscope. Such a procedure can be difficult to standardize and can lead to overcalling of melanomas.
Once a diagnosis of melanoma is made by morphological assessment, the risk of metastasis is typically determined by the invasion depth of malignant cells into the skin (i.e., the Breslow depth). The Breslow depth can dictate further work-up such as a need for an invasive sentinel lymph node (SLN) procedure. Such procedures, however, can lead to inaccurate determinations of the true malignant potential of a pigmented lesion.
SUMMARYThis document provides methods and materials for identifying metastatic malignant skin lesions (e.g., metastatic malignant pigmented skin lesions). For example, this document provides methods and materials for using quantitative PCR results and correction protocols to reduce the impact of basal keratinocyte contamination on the analysis of test sample results to identify metastatic malignant skin lesions.
As described herein, quantitative PCR can be performed using a routine skin biopsy sample (e.g., a paraffin-embedded tissue biopsy) to obtain expression data (e.g., gene copy numbers) for one or more marker genes. Correction protocols can be used to reduce the impact of basal keratinocyte contamination on the analysis of the expression data from the test sample. For example, the contribution of gene expression from basal keratinocytes present within the test skin sample can be determined and removed from the overall gene expression values to determine the final gene expression value for a particular gene as expressed from cells other than basal keratinocytes (e.g., melanocytes). An assessment of the final gene expression values, which include minimal, if any, contribution from basal keratinocytes, for a collection of marker genes can be used to determine the benign or malignant or metastatic biological behavior of the tested skin lesion.
This document also provides methods and materials for treating skin cancer. For example, this document provides methods and materials for identifying a mammal (e.g., a human) having a pre-metastatic skin lesion (e.g., pre-metastatic melanoma) and treating that mammal with pentamidine.
As described herein, aggressive cancer cells (e.g., melanoma cells) can remodel their cell adhesion structures (e.g., osteopontin (SPP1) polypeptides) to invade tissues and metastasize. Screening over 1,200 compounds for the ability to reduce expression of SPP1 polypeptides resulted in the identification of pentamidine as an effective agent for disrupting integrin adhesion remodeling, thereby demonstrating that pentamidine can be used to reduce or inhibit cancer progression at an early stage (e.g., prior to metastatic cancer). In some cases, a mammal (e.g., a human) identified as having skin cancer cells that express an elevated level of PLAT, ITGB3, LAMB1, and/or TP53 can be administered pentamidine to reduce or inhibit cancer progression. For example, pentamidine can be administered to a mammal (e.g., a human) having pre-metastatic melanoma cells that were determined to have an elevated level of PLAT, ITGB3, LAMB1, and/or TP53 expression. In such cases, the mammal being treated with pentamidine may not experience cancer progression from the pre-metastatic melanoma state to a metastatic melanoma state.
In general, one aspect of this document features a method for identifying a metastatic malignant skin lesion. The method comprises, or consists essentially of, (a) determining, within a test sample, the expression level of a marker gene selected from the group consisting of PLAT, ITGB3, LAMB1, and TP53 to obtain a measured expression level of the marker gene for the test sample, (b) determining, within the test sample, the expression level of a keratinocyte marker gene to obtain a measured expression level of the keratinocyte marker gene for the test sample, (c) removing, from the measured expression level of the marker gene for the test sample, a level of expression attributable to keratinocytes present in the test sample using the measured expression level of the keratinocyte marker gene for the test sample and a keratinocyte correction factor to obtain a corrected value of marker gene expression for the test sample, and (d) identifying the test sample as containing a metastatic malignant skin lesion based, at least in part, on the corrected value of marker gene expression for the test sample. The keratinocyte marker gene can be K14. The marker gene can be PLAT or ITGB3. The step (c) can comprise (i) multiplying the measured expression level of the keratinocyte marker gene for the test sample by the keratinocyte correction factor to obtain a correction value and (ii) subtracting the correction value from the measured expression level of the marker gene for the test sample to obtain the corrected value of marker gene expression for the test sample. The method can comprise determining, within the test sample, the expression level of at least two marker genes selected from the group consisting of PLAT, ITGB3, LAMB1, and TP53 to obtain measured expression levels of the at least two marker genes for the test sample. The method can comprise determining, within the test sample, the expression level of at least three marker genes selected from the group consisting of PLAT, ITGB3, LAMB1, and TP53 to obtain measured expression levels of the at least three marker genes for the test sample. The method can comprise determining, within the test sample, the expression level of PLAT, ITGB3, LAMB1, and TP53 to obtain measured expression levels of the PLAT, ITGB3, LAMB1, and TP53 for the test sample.
In another aspect, this document features a kit for identifying a metastatic malignant skin lesion. The kit comprises, or consists essentially of, (a) a primer pair for determining, within a test sample, the expression level of a marker gene selected from the group consisting of LAMB1 and TP53 to obtain a measured expression level of the marker gene for the test sample, and (b) a primer pair for determining, within the test sample, the expression level of a keratinocyte marker gene to obtain a measured expression level of the keratinocyte marker gene for the test sample. The keratinocyte marker gene can be K14. The marker gene can be LAMB1. The marker gene can be TP53. The kit can comprise primer pairs for determining, within the test sample, the expression level of LAMB1 and TP53 to obtain measured expression levels of the LAMB1 and TP53 for the test sample. The kit can comprise primer pairs for determining, within the test sample, the expression level of PLAT to obtain measured expression levels of the PLAT for the test sample. The kit can comprise primer pairs for determining, within the test sample, the expression level of ITGB3 to obtain measured expression levels of the ITGB3 for the test sample. The kit can comprise primer pairs for determining, within the test sample, the expression level of PLAT and ITGB3 to obtain measured expression levels of the ITGB3 and PLAT for the test sample.
In another aspect, this document features a method for identifying a metastatic malignant skin lesion. The method comprises, or consists essentially of, (a) determining, within a test sample, the expression level of a marker gene selected from the group consisting of PLAT, ITGB3, LAMB1, and TP53 to obtain a measured expression level of the marker gene for the test sample, (b) determining, within the test sample, the expression level of a keratinocyte marker gene to obtain a measured expression level of the keratinocyte marker gene for the test sample, (c) removing, from the measured expression level of the marker gene for the test sample, a level of expression attributable to keratinocytes present in the test sample using the measured expression level of the keratinocyte marker gene for the test sample and a keratinocyte correction factor to obtain a corrected value of marker gene expression for the test sample, and (d) identifying the test sample as containing a metastatic malignant skin lesion based, at least in part, on the corrected value of marker gene expression for the test sample. The keratinocyte marker gene can be K14. The marker gene can be LAMB1 or TP53. The step (c) can comprise (i) multiplying the measured expression level of the keratinocyte marker gene for the test sample by the keratinocyte correction factor to obtain a correction value and (ii) subtracting the correction value from the measured expression level of the marker gene for the test sample to obtain the corrected value of marker gene expression for the test sample.
In another aspect, this document features a method for identifying a pre-metastatic skin lesion having an increased likelihood of metastasizing. The method comprises, or consists essentially of, (a) detecting the presence of an elevated level of PLAT, ITGB3, LAMB1, and TP53 expression in cells of the pre-metastatic skin lesion, and (d) classifying the pre-metastatic skin lesion as having an increased likelihood of metastasizing based, at least in part, on the presence. The method can comprise measuring the levels of PLAT, ITGB3, LAMB1, and TP53 expression in cells of the pre-metastatic skin lesion and performing an analysis using a 2 trees, 2 leaves model. The pre-metastatic skin lesion can be a human pre-metastatic skin lesion.
In another aspect, this document features a method for treating skin cancer, wherein the method comprises, or consists essentially of, (a) detecting the presence of an elevated level of PLAT, ITGB3, LAMB1, and TP53 expression in skin cancer cells of a mammal, and (d) administering pentamidine to the mammal. The mammal can be a human. The skin cancer can be pre-metastatic skin cancer. The skin cancer can be pre-metastatic melanoma. Administration of the pentamidine can reduce the progression of the pre-metastatic melanoma to metastatic melanoma. The pre-metastatic melanoma can fail to progress to metastatic melanoma following administration of the pentamidine. The method can comprise measuring the levels of PLAT, ITGB3, LAMB1, and TP53 expression in cells of the skin cancer cells and performing an analysis using a 2 trees, 2 leaves model.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.
Other features and advantages of the invention will be apparent from the following detailed description, and from the claims.
This document provides methods and materials for identifying metastatic malignant skin lesions (e.g., metastatic malignant pigmented skin lesions). For example, this document provides methods and materials for using quantitative PCR results and correction protocols to reduce the impact of basal keratinocyte contamination on the analysis of test sample results to identify metastatic malignant skin lesions.
At box 108, the quality of the obtained standard curves can be confirmed. In some cases, a gene of interest included in the assay format can be a melanocyte marker (e.g., levels of MLANA and/or MITF expression) to confirm the presence of melanocytes in the test sample. Other examples of melanocyte markers that can be used as described herein include, without limitation, TYR, TYRP1, DCT, PMEL, OCA2, MLPH, and MC1R.
At box 110, the raw copy number of each target present in the test sample is determined using the Ct values and the standard curve for each target. In some cases, the averaged, corrected copy number for each gene is calculated using the raw copy number of each target of a particular gene and the internal control value for each primer set (box 112). This averaged, corrected copy number value for each gene can be normalized to a set number of one or more housekeeping genes as set forth in box 114. For example, each averaged, corrected copy number value for each gene can be normalized to 100,000 copies of the combination of ACTB, RPL8, RPLP0, and B2M. Other examples of housekeeping genes that can be used as described herein include, without limitation, RRN18S, GAPDH, PGK1, PPIA, RPL13A, YWHAZ, SDHA, TFRC, ALAS1, GUSB, HMBS, HPRT1, TBP, CLTC, MRFAP1, PPP2CA, PSMA1, RPL13A, RPS29, SLC25A3, TXNL1, and TUPP. Once normalized, the copy number values for each gene can be referred to as the averaged, corrected, normalized copy number for that gene as present in the test sample.
At box 116, the averaged, corrected, normalized copy number for each gene can be adjusted to remove the copy number contamination from basal keratinocytes present in the test sample. In general, copy number contamination from basal keratinocytes can be removed by (a) determining a keratinocyte correction factor for the gene of interest using one or more keratinocyte markers (e.g., keratin 14 (K14)) and one or more normal skin samples (e.g., FFPE-embedded normal skin samples), (b) determining the averaged, corrected, normalized copy number value for the one or more keratinocyte markers of the test sample and multiplying that value by the keratinocyte correction factor to obtain a correction value for the gene of interest, and (c) subtracting that correction value from the averaged, corrected, normalized copy number value of the gene of interest to obtain the final copy number for the gene of interest. Examples of keratinocyte markers that can be used as described herein include, without limitation, KRT5, KRT1, KRT10, KRT17, ITGB4, ITGA6, PLEC, DST, and COL17A1.
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Computing device 1400 includes a processor 1402, memory 1404, a storage device 1406, a high-speed interface 1408 connecting to memory 1404 and high-speed expansion ports 1410, and a low speed interface 1415 connecting to low speed bus 1414 and storage device 1406. Each of the components 1402, 1404, 1406, 1408, 1410, and 1415, are interconnected using various busses, and may be mounted on a common motherboard or in other manners as appropriate. The processor 1402 can process instructions for execution within the computing device 1400, including instructions stored in the memory 1404 or on the storage device 1406 to display graphical information for a GUI on an external input/output device, such as display 1416 coupled to high speed interface 1408. In other implementations, multiple processors and/or multiple buses may be used, as appropriate, along with multiple memories and types of memory. Also, multiple computing devices 1400 may be connected, with each device providing portions of the necessary operations (e.g., as a server bank, a group of blade servers, or a multi-processor system).
The memory 1404 stores information within the computing device 1400. In one implementation, the memory 1404 is a volatile memory unit or units. In another implementation, the memory 1404 is a non-volatile memory unit or units. The memory 1404 may also be another form of computer-readable medium, such as a magnetic or optical disk.
The storage device 1406 is capable of providing mass storage for the computing device 1400. In one implementation, the storage device 1406 may be or contain a computer-readable medium, such as a floppy disk device, a hard disk device, an optical disk device, or a tape device, a flash memory or other similar solid state memory device, or an array of devices, including devices in a storage area network or other configurations. A computer program product can be tangibly embodied in an information carrier. The computer program product may also contain instructions that, when executed, perform one or more methods, such as those described herein. The information carrier is a computer- or machine-readable medium, such as the memory 1404, the storage device 1406, memory on processor 1402, or a propagated signal.
The high speed controller 1408 manages bandwidth-intensive operations for the computing device 1400, while the low speed controller 1415 manages lower bandwidth-intensive operations. Such allocation of functions is exemplary only. In one implementation, the high-speed controller 1408 is coupled to memory 1404, display 1416 (e.g., through a graphics processor or accelerator), and to high-speed expansion ports 1410, which may accept various expansion cards (not shown). In the implementation, low-speed controller 1415 is coupled to storage device 1406 and low-speed expansion port 1414. The low-speed expansion port, which may include various communication ports (e.g., USB, Bluetooth, Ethernet, or wireless Ethernet) may be coupled to one or more input/output devices, such as a keyboard, a pointing device, a scanner, an optical reader, a fluorescent signal detector, or a networking device such as a switch or router, e.g., through a network adapter.
The computing device 1400 may be implemented in a number of different forms, as shown in the figure. For example, it may be implemented as a standard server 1420, or multiple times in a group of such servers. It may also be implemented as part of a rack server system 1424. In addition, it may be implemented in a personal computer such as a laptop computer 1422. In some cases, components from computing device 1400 may be combined with other components in a mobile device (not shown), such as device 1450. Each of such devices may contain one or more of computing device 1400, 1450, and an entire system may be made up of multiple computing devices 1400, 1450 communicating with each other.
Computing device 1450 includes a processor 1452, memory 1464, an input/output device such as a display 1454, a communication interface 1466, and a transceiver 1468, among other components (e.g., a scanner, an optical reader, a fluorescent signal detector). The device 1450 may also be provided with a storage device, such as a microdrive or other device, to provide additional storage. Each of the components 1450, 1452, 1464, 1454, 1466, and 1468, are interconnected using various buses, and several of the components may be mounted on a common motherboard or in other manners as appropriate.
The processor 1452 can execute instructions within the computing device 1450, including instructions stored in the memory 1464. The processor may be implemented as a chipset of chips that include separate and multiple analog and digital processors. The processor may provide, for example, for coordination of the other components of the device 1450, such as control of user interfaces, applications run by device 1450, and wireless communication by device 1450.
Processor 1452 may communicate with a user through control interface 1458 and display interface 1456 coupled to a display 1454. The display 1454 may be, for example, a TFT LCD (Thin-Film-Transistor Liquid Crystal Display) or an OLED (Organic Light Emitting Diode) display, or other appropriate display technology. The display interface 1456 may comprise appropriate circuitry for driving the display 1454 to present graphical and other information to a user. The control interface 1458 may receive commands from a user and convert them for submission to the processor 1452. In addition, an external interface 1462 may be provide in communication with processor 1452, so as to enable near area communication of device 1450 with other devices. External interface 1462 may provide, for example, for wired communication in some implementations, or for wireless communication in other implementations, and multiple interfaces may also be used.
The memory 1464 stores information within the computing device 1450. The memory 1464 can be implemented as one or more of a computer-readable medium or media, a volatile memory unit or units, or a non-volatile memory unit or units. Expansion memory 1474 may also be provided and connected to device 1450 through expansion interface 1472, which may include, for example, a SIMM (Single In Line Memory Module) card interface. Such expansion memory 1474 may provide extra storage space for device 1450, or may also store applications or other information for device 1450. For example, expansion memory 1474 may include instructions to carry out or supplement the processes described herein, and may include secure information also. Thus, for example, expansion memory 1474 may be provide as a security module for device 1450, and may be programmed with instructions that permit secure use of device 1450. In addition, secure applications may be provided via the SIMM cards, along with additional information, such as placing identifying information on the SIMM card in a non-hackable manner.
The memory may include, for example, flash memory and/or NVRAM memory, as discussed below. In one implementation, a computer program product is tangibly embodied in an information carrier. The computer program product contains instructions that, when executed, perform one or more methods, such as those described herein. The information carrier is a computer- or machine-readable medium, such as the memory 1464, expansion memory 1474, memory on processor 1452, or a propagated signal that may be received, for example, over transceiver 1468 or external interface 1462.
Device 1450 may communicate wirelessly through communication interface 1466, which may include digital signal processing circuitry where necessary. Communication interface 1466 may provide for communications under various modes or protocols, such as GSM voice calls, SMS, EMS, or MMS messaging, CDMA, TDMA, PDC, WCDMA, CDMA2000, or GPRS, among others. Such communication may occur, for example, through radio-frequency transceiver 1468. In addition, short-range communication may occur, such as using a Bluetooth, WiFi, or other such transceiver (not shown). In addition, GPS (Global Positioning System) receiver module 1470 may provide additional navigation- and location-related wireless data to device 1450, which may be used as appropriate by applications running on device 1450.
Device 1450 may also communicate audibly using audio codec 1460, which may receive spoken information from a user and convert it to usable digital information. Audio codec 1460 may likewise generate audible sound for a user, such as through a speaker, e.g., in a handset of device 1450. Such sound may include sound from voice telephone calls, may include recorded sound (e.g., voice messages, music files, etc.) and may also include sound generated by applications operating on device 1450.
The computing device 1450 may be implemented in a number of different forms, as shown in the figure. For example, it may be implemented as a cellular telephone 1480. It may also be implemented as part of a smartphone 1482, personal digital assistant, or other similar mobile device.
Various implementations of the systems and techniques described herein can be realized in digital electronic circuitry, integrated circuitry, specially designed ASICs (application specific integrated circuits), computer hardware, firmware, software, and/or combinations thereof. These various implementations can include implementation in one or more computer programs that are executable and/or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.
These computer programs (also known as programs, software, software applications or code) include machine instructions for a programmable processor, and can be implemented in a high-level procedural and/or object-oriented programming language, and/or in assembly/machine language. As used herein, the terms “machine-readable medium” and “computer-readable medium” refer to any computer program product, apparatus and/or device (e.g., magnetic discs, optical disks, memory, and Programmable Logic Devices (PLDs)) used to provide machine instructions and/or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term “machine-readable signal” refers to any signal used to provide machine instructions and/or data to a programmable processor.
To provide for interaction with a user, the systems and techniques described herein can be implemented on a computer having a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form, including acoustic, speech, or tactile input.
The systems and techniques described herein can be implemented in a computing system that includes a back end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front end component (e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the systems and techniques described herein), or any combination of such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include a local area network (“LAN”), a wide area network (“WAN”), and the Internet.
The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other.
This document also provides methods and materials involved in treating mammals having skin cancer (e.g., melanoma such as pre-metastatic melanoma) by administering pentamidine to the mammal. Any appropriate mammal having skin cancer can be treated as described herein. For example, humans and other primates such as monkeys having skin cancer can be treated with pentamidine. In some cases, dogs, cats, horses, bovine species, porcine species, mice, or rats can be treated with pentamidine as described herein. In addition, a mammal having any particular type of skin cancer can be treated as described herein. For example, a mammal having melanoma, pre-metastatic melanoma, locally metastatic melanoma (i.e., skin in close proximity to primary melanoma), regionally metastatic melanoma (e.g., metastases to regional sentinel lymph nodes), or distant metastases (e.g., metastases to internal organs) can be treated with pentamidine as described herein. In some cases, a mammal determined to have skin cancer cells that express an elevated level of one or more marker genes described herein (e.g., PLAT, ITGB3, LAMB1, and/or TP53) can be treated with pentamidine. In some cases, a mammal (e.g., a human) determined to have skin cancer cells that express an elevated level of one or more marker genes (e.g., PLAT, ITGB3, LAMB1, and/or TP53) using the methods or materials provided herein can be treated with pentamidine.
Any appropriate method can be used to identify a mammal having skin cancer (e.g., pre-metastatic melanoma) that can be treated using pentamidine. For example, imaging, biopsy, pathology, PCR, and sequencing techniques can be used to identify a human having skin cancer cells that express an elevated level of PLAT, ITGB3, LAMB1, and/or TP53.
Once identified as having skin cancer or skin cancer that expresses an elevated level of PLAT, ITGB3, LAMB1, and/or TP53, the mammal can be administered pentamidine. In some cases, pentamidine can be administered in combination with a chemotherapeutic agent to treat skin cancer (e.g., pre-metastatic melanoma). Examples of chemotherapeutic agents that can be used in combination with pentamidine include, without limitation, taxane therapies, anthracycline therapies, and gemcitabine therapies. Examples of taxane therapies include, without limitation, cancer treatments that involve administering taxane agents such as paclitaxel, docetacel, or other microtubule disrupting agents such as vinblastine, vincristine, or vinorelbine. In some cases, drugs used to treat gout or chochicine can be used as described herein to treat a mammal having skin cancer. Examples of anthracycline therapies include, without limitation, cancer treatments that involve administering anthracycline agents such as doxorubicine, daunorubicin, epirubicin, idarubicin, valrubicin, or mitoxantrone.
In some cases, pentamidine can be formulated into a pharmaceutically acceptable composition for administration to a mammal having skin cancer (e.g., pre-metastatic melanoma). For example, a therapeutically effective amount of pentamidine can be formulated together with one or more pharmaceutically acceptable carriers (additives) and/or diluents. A pharmaceutical composition can be formulated for administration in solid or liquid form including, without limitation, sterile solutions, suspensions, sustained-release formulations, tablets, capsules, pills, powders, and granules.
Pharmaceutically acceptable carriers, fillers, and vehicles that may be used in a pharmaceutical composition described herein include, without limitation, ion exchangers, alumina, aluminum stearate, lecithin, serum proteins, such as human serum albumin, buffer substances such as phosphates, glycine, sorbic acid, potassium sorbate, partial glyceride mixtures of saturated vegetable fatty acids, water, salts or electrolytes, such as protamine sulfate, disodium hydrogen phosphate, potassium hydrogen phosphate, sodium chloride, zinc salts, colloidal silica, magnesium trisilicate, polyvinyl pyrrolidone, cellulose-based substances, polyethylene glycol, sodium carboxymethylcellulose, polyacrylates, waxes, polyethylene-polyoxypropylene-block polymers, polyethylene glycol and wool fat.
A pharmaceutical composition containing pentamidine can be designed for oral or parenteral (including subcutaneous, intramuscular, intravenous, and intradermal) administration. When being administered orally, a pharmaceutical composition containing pentamidine can be in the form of a pill, tablet, or capsule. Compositions suitable for parenteral administration include aqueous and non-aqueous sterile injection solutions that can contain anti-oxidants, buffers, bacteriostats, and solutes that render the formulation isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions that may include suspending agents and thickening agents. The formulations can be presented in unit-dose or multi-dose containers, for example, sealed ampules and vials, and may be stored in a freeze dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example water for injections, immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules, and tablets.
Such injection solutions can be in the form, for example, of a sterile injectable aqueous or oleaginous suspension. This suspension may be formulated using, for example, suitable dispersing or wetting agents (such as, for example, Tween 80) and suspending agents. The sterile injectable preparation can be a sterile injectable solution or suspension in a non-toxic parenterally-acceptable diluent or solvent, for example, as a solution in 1,3-butanediol. Examples of acceptable vehicles and solvents that can be used include, without limitation, mannitol, Ringer's solution, and isotonic sodium chloride solution. In addition, sterile, fixed oils can be used as a solvent or suspending medium. In some cases, a bland fixed oil can be used such as synthetic mono- or di-glycerides. Fatty acids, such as oleic acid and its glyceride derivatives can be used in the preparation of injectables, as can natural pharmaceutically-acceptable oils, such as olive oil or castor oil, including those in their polyoxyethylated versions. In some cases, these oil solutions or suspensions can contain a long-chain alcohol diluent or dispersant.
In some cases, a pharmaceutically acceptable composition including pentamidine can be administered locally or systemically. For example, a composition containing pentamidine can be administered locally by injection into lesions at surgery or by subcutaneous administration of a sustained release formulation. In some cases, a composition containing pentamidine can be administered systemically orally or by injection to a mammal (e.g., a human).
Effective doses can vary depending on the severity of the cancer, the route of administration, the age and general health condition of the subject, excipient usage, the possibility of co-usage with other therapeutic treatments such as use of chemotherapeutic agents, and the judgment of the treating physician.
An effective amount of a composition containing pentamidine can be any amount that reduces skin cancer progression without producing significant toxicity to the mammal. For example, an effective amount of pentamidine can be from about 0.01 mg/kg to about 4 mg/kg. In some cases, between about 10 mg and about 1500 mg of pentamidine can be administered to an average sized human (e.g., about 70-75 kg human) daily for about one week to about one year (e.g., about two weeks to about four months). If a particular mammal fails to respond to a particular amount, then the amount of pentamidine can be increased by, for example, two fold. After receiving this higher amount, the mammal can be monitored for both responsiveness to the treatment and toxicity symptoms, and adjustments made accordingly. The effective amount can remain constant or can be adjusted as a sliding scale or variable dose depending on the mammal's response to treatment. Various factors can influence the actual effective amount used for a particular application. For example, the frequency of administration, duration of treatment, use of multiple treatment agents, route of administration, and severity of the cancer may require an increase or decrease in the actual effective amount administered.
The frequency of administration can be any frequency that reduces skin cancer progression without producing significant toxicity to the mammal. For example, the frequency of administration can be from about once a week to about once every two to three weeks. The frequency of administration can remain constant or can be variable during the duration of treatment. A course of treatment with a composition containing pentamidine can include rest periods. For example, a composition containing pentamidine can be administered daily over a two week period followed by a two week rest period, and such a regimen can be repeated multiple times. As with the effective amount, various factors can influence the actual frequency of administration used for a particular application. For example, the effective amount, duration of treatment, use of multiple treatment agents, route of administration, and severity of the cancer may require an increase or decrease in administration frequency.
An effective duration for administering a composition containing pentamidine can be any duration that reduces skin cancer progression without producing significant toxicity to the mammal. Thus, the effective duration can vary from several days to several weeks, months, or years. In general, the effective duration for the treatment with pentamidine to reduce skin cancer progression can range in duration from six months to one year. Multiple factors can influence the actual effective duration used for a particular treatment. For example, an effective duration can vary with the frequency of administration, effective amount, use of multiple treatment agents, route of administration, and severity of the condition being treated.
In certain instances, a course of treatment and the severity of one or more symptoms related to the skin cancer being treated (e.g., pre-metastatic melanoma) can be monitored. Any appropriate method can be used to determine whether or not cancer progression is reduced. For example, the severity of a symptom of skin cancer can be assessed using imagine and pathology assessment of biopsy samples or surgical samples.
The invention will be further described in the following examples, which do not limit the scope of the invention described in the claims.
EXAMPLES Example 1—Marker Genes that Discriminate Between Benign and Malignant TissueMarker genes were ordered by their ability to differentiate benign from malignant tissue (Table A). This was based on the analysis of 73 benign and 53 malignant tissues, and the hypothesis that changes in expression of fibronectin-associated gene networks are indicative of malignant cell behavior. Values of the test statistic were for the Wilcoxon rank sum test. The values of the test statistic for a Winsorized two-sample test (trimmed outliers were replaced with actual values) and for the chi-square test for the zero vs. >zero versions of each variable were included. The top 5 discriminatory genes based on each statistical test were highlighted in bold.
The candidate gene list from Example 1 was modified to include other FN1 network genes as well as four housekeeping genes (ACTB, RPLP0, RPL8, and B2M), two keratinocyte markers (K10 and K14) to assess keratinocyte contamination, and four melanocyte markers (MITF, TYR, MLANA and PMEL) to assess melanocyte content in the skin sections. Genes from Example 1 with low discriminatory value and a more distant neighborhood to FN1 were excluded from the test setup (LAMC1, LOXL2, CYR61, YAP, BGN, LAMB1, THBS2, COL18A1, SPARC, TP53, PLOD2, CCL2, FBLN2, LAMA1, THBS4, COL1A1, TAZ, POSTN, LOX, CSRC, LAMA3, CDKN1A, CDKN2A, LAMC2, PCOLCE2, LOXL4, PCOLCE, LAMB3, and CSF2). Instead, the discriminatory ability of other FN1 network genes was determined (PLAT, CSK, GDF15, FARP1, ARPC1B, NES, NTRK3, SNX17, L1CAM, and CD44). The following results were based on the analysis of 26 benign nevi and 52 primary cutaneous melanomas with documented subsequent metastasis or skin lesions of melanoma metastasis (Table B). The top 5 genes were highlighted.
Based on the results of Example 1 and above, FN1 was identified as a component of the melanoma phenotype that is at the core of a gene network that discriminates between benign and malignant melanocytic skin lesions (
The list of all 71 genes tested is provided in Table 1.
Gene expression of target genes was assessed by SYBR/EVA-Green based RT-PCR. All tested genes were accompanied by a standard curve for quantification of absolute copy number per a defined number of housekeeping genes. mRNA extraction from paraffin-embedded biospecimen was performed using an extraction protocol (Qiagen RNA FFPE extraction kit) and an extraction robot (Qiacube from Qiagen). mRNA was transcribed into cDNA using a commercially available kit (iScript kit from BioRad), and Fluidigm technology was used for PCR cycling.
The primer design was performed using web-based open access software. The primers were HPLC purified to minimize background and were optimized for formalin-fixed, paraffin-embedded (FFPE) tissue (i.e., highly degraded tissue). The primers were designed to detect a maximum number of gene transcripts and were designed to be cDNA specific (i.e., not affected by genomic DNA contamination of the total, tissue-derived cDNA). The housekeeping genes, keratin genes, melanocyte-specific genes, and selected high interest genes were detected using four separate and individually designed primer pairs. The primer pairs are set forth in Table 2.
The following was performed to generate a standard curve for the target of each primer pair. The standard was generated with a defined number of amplicons per volume for each primer pair. In particular, a standard (S7) was designed to contain about 5 million copies of amplicon-containing cDNA in a bacterial expression vector backbone (pJET1.2 obtained from Fermentas) per one microliter volume for each primer pair. From this, six 1:10 dilutions were generated such that seven standards S1 to S7 were obtained ranging from 5 to 5 million copies of amplicon. To obtain fragments of cDNA, total RNA was extracted from the human HaCaT, A431, and A375 cell lines, and the RNA was reverse transcribed into cDNA. Cell line-derived cDNA was used as a template to amplify fragments of cDNA that contained the desired amplicons for the real time-PCR primer pairs. A list of primers used to generate the desired cDNA fragments is listed in Table 3.
The PCR reactions were performed using a high-fidelity polymerase (product name: ‘Phusion’, obtained from New England Biolabs). PCR amplification products were checked for correct size and subsequently gel purified using the Qiagen Gel Extraction kit. Purified PCR fragments were subcloned into the bacterial expression vector pJET1.2 using a commercially available kit (Fermentas). The subcloned fragments were subsequently checked by restriction digest and DNA sequencing. Bacterial clones harboring the pJET1.2 expression vector with the correct PCR insert (containing the desired amplicon for real time PCR primer pairs) were frozen and stored at −80° C. This was done to regenerate the same real time PCR standards over time.
Bacteria harboring the pJET1.2 expression vector with PCR inserts were cultured to generate sufficient amounts of vector. A small aliquot of the total retrieved expression vector with insert was linearized using the PvuI-HF restriction enzyme (from New England Biolabs). The digest was then purified using the Qiagen PCR purification kit. Linearized cDNA was diluted to a concentration of 20 ng/μL. One μL of each of a total of 71 linearized cDNA fragments (each at a 20 ng/μL concentration) were mixed and brought to a final volume of 1 mL to obtain standard S7.
Standard S7 was then diluted six times at a 1:10 ratio to obtained standards 51 to S6. Dilution was performed using ultrapure water obtained from Promega (Cat. No. P1193).
The following was performed to generate cDNA from FFPE samples. FFPE blocks were cut at 20 μm sections using a standard Leica microtome. For large pieces of tissue, 2×20 μm full sections were used for RNA retrieval. For smaller tissues, up to 5×20 μm sections were combined for RNA retrieval. RNA extraction was performed using the Qiagen RNA FFPE retrieval kit and a Qiagen QiaCube extraction robot. 0.5 to 1 μg of RNA with a 260/280 ratio of greater than 1.8 were transcribed into cDNA using the BioRad iScript cDNA Synthesis kit. All biospecimens were annotated with clinical data from Mayo Clinic databases. H&E stained sections were obtained for each block analyzed and digitalized using a high-resolution slide scanner.
Fluidigm RT-PCR was performed using a 96×96 format for high throughput analysis (i.e., 96 cDNAs were analyzed for 96 markers; 9216 data points). The primer pairs and cDNAs were prepared in a 96 well format. Standard curves were calculated for each primer pair. Copy numbers per 100,000 housekeeping genes were calculated for each primer pair and averaged per gene. This was initially done for cDNAs derived from FFPE-embedded skin. To correct for epidermal cell-derived cross-contamination, background signal per one copy of K14 (a basal keratinocyte marker) was calculated from FFPE-embedded normal skin samples for each primer pair and averaged. Experimental samples were then normalized first to 100,000 housekeeping genes and then background-corrected for epidermal cross-contamination based on K14 copy number. In particular, the keratinocyte correction factor used for each gene is set forth in Table E under the column titled “AVG per copy K14.”
The study design (Example 1) involved a comparison of the expression profile of ‘true’ benign pigmented skin lesions (nevi, n=73) with ‘true’ malignant melanomas of the skin. The latter comprised i) primary skin melanomas that were documented to metastasize, either to regional lymph nodes, to other areas of skin (in-transit), or to other organs; and ii) in-transit or comparison of nevi to in-transit melanoma metastases (n=54).
Tables C and D summarize the comparisons of the gene expressions between the 73 benign and 54 metastatic. Table A compares the ranked values using the Wilcoxon rank sum test, and Table E compares the dichotomized values (zero vs. >0) using the chi-square test.
A recursive partitioning approach was used to identify cut-points for the genes that would discriminate between these two groups. After partitioning the data at a cut-point of 45 for FN1, no further additional splits in the data based on the other genes were identified by this method.
Using a cutoff of 45 for FN1, the sensitivity was 92.6%, and the specificity was 98.6%. These results are provided in Tables 4 and 5 along with the next possible cutoff for FN1 at 124
The ability to further discriminate between the groups was assessed by considering SPP1 or ITGB3 in addition to FN1.
Benign vs. Malignant—Option 1 using FN1 and SPP1 (
The results are set forth in Table 6.
Benign Vs. Malignant—Option 2 Using FN1 and ITGB3 (
The results are set forth in Table 7.
If all three genes are included, the rule was as follows:
FN1<45 and SPP1=0 and ITGB3=0 denotes a negative test
-
- vs.
all other combinations denotes a positive test.
This rule resulted in a specificity of 72/73 (98.6%), and a sensitivity of 53/54 (98.2%) (Table 8). Compared to a rule using FN1 alone, the specificity stayed the same but the sensitivity increased from 92.6% to 98.2% using this new rule.
The rule was evaluated using 25 additional malignant patients who did not have mets (from the “Breslow” file). For 19 of these 25 patients, the rule was ‘negative’ (Table 9).
The rule also was evaluated using 33 thin melanomas (Table 10). For 25 of these 33 patients, the rule was ‘negative’.
The results provided herein demonstrate the development of a method for determining absolute levels (copy numbers) of genes of interest (e.g., FN-associated genes) from paraffin-embedded tissue by generating a highly defined internal standard that can be regenerated indefinitely. This standardization approach can allow for the comparison of results from independent experiments and thus, allows for extensive validation. The RT-PCR not only produced strong signals from highly degraded RNA due to FFPE embedding, but also was amendable to high-throughput analysis and was highly cost effective. While the methods provided herein were validated for melanoma, these methods are likely applicable to other human cancers. The results provided herein also demonstrate the discrimination between benign and malignant pigmented lesions based on multiple markers.
Example 3—Additional Marker PanelA test kit panel was designed to include primers for assessing expression levels of eight marker genes (ITGB3, TNC, SPP1, SPARC, PLAT, COL4A1, PLOD3, and PTK2) as well as three housekeeping genes (ACTB, RPLP0, and RPL8), one keratinocyte markers (K14) to assess keratinocyte contamination, and two melanocyte markers (MLANA and MITF) to assess melanocyte content in the skin sections. The primers designed for this collection are set forth in Table 11.
One purpose of the kit was to differentiate between melanoma with high and low risk of regional metastasis, and to appropriately select patients for surgical procedures such as sentinel lymph node biopsy (SLNB) or total lymphadenectomy. Another purpose of this kit was to estimate disease-free survival, disease relapse, or likelihood of death from melanoma. To study the ability of these methods to discriminate between melanoma with high and low risk of metastasis and to establish superiority to established methods, a cohort of 158 patients between October 1998 and June 2013 were identified as having been diagnosed with high-risk melanoma and as having underwent SLNB with the intention to assess metastatic potential of the tumor. Of note, high-risk melanoma by current criteria are defined as melanoma with an invasion depth (Breslow depth) of ≧1 mm; or melanoma with an invasion depth of 0.75 to 0.99 mm plus the presence of either one of the following three risk factors: >0 mitotic figures/mm2; tumor ulceration present; patient age <40 years.
All 158 patients met the criteria for high risk. 136 patients had a Breslow Depth ≧1 mm. 22 patients had a Breslow Depth between 0.75 and 0.99 and had at least 1 of the aforementioned 3 risk factors (ulceration, mitotic rate >0, age <40). Of the 158 patients, 36 (22.8%) had a melanoma-positive SLNB.
To select genes for a test kit from a pool of genes, the expression level of 52 genes (variables) was initially determined and dichotomized as zero vs. >zero and evaluated for an association with positive SLNB using the chi-square test for a 2×2 contingency level. The genes are ordered based on the value of the chi-square test statistic (Table 12).
As can be deduced from the chi-square test statistic, ITGB3 was highly discriminatory between melanoma with and without regional lymph node metastasis. The n (%) with a positive SLNB for those with no expression vs. expression level >0 was summarized (Table 13).
To formulate a model that distinguishes melanoma that presents with regional metastasis at the time of diagnosis vs. no metastasis, logic regression was used. Logic regression is a machine learning technique that uses Boolean explanatory variables. There was not a typical technique to create good cut points for logic regression. To assign cut points in the variables, recursive partitioning followed by standardization of cut point levels was used. These were arbitrarily set at 0, 50, 250, and 500. Cut points derived by logic regression were adjusted to the next highest standard level. The cut point for ITGB3 was maintained at 0. The selected model for predicting metastasis was the following:
IF(OR(ITGB3>0,(AND(OR(PTK2>250,PLAT>500,PLOD3>250),CDKN2A<50)))=TRUE then predict metastasis
Cut point ITGB3=0
Cut point PLAT=500
Cut point PTK2=250
Cut point PLOD3=250
Cut point CDKN2A=50
As can be seen from the formula, the risk of melanoma metastasis was high if ITGB3, PLAT, PTK2 or PLOD3 levels are increased and CDKN2A is low.
This model predicted regional metastasis (defined as a positive SLN biopsy at the time of primary cancer diagnosis) with a specificity of 80.3% and sensitivity of 97.3%.
Example 4—Use of Integrin Adhesions as a Biomarker of Melanoma Sentinel Lymph Node Metastasis Patient Sample Model Development CohortAll patients with a diagnosis of malignant primary skin melanoma who had a SLN biopsy performed within 90 days of their diagnosis at Mayo Clinic Rochester, Mayo Clinic Arizona, or Mayo Clinic Florida were identified. The diagnosis of melanoma and all related histopathology data were established by ≧2 board-certified Mayo Clinic dermatopathologists. Patients evaluated at Mayo Clinic Rochester were excluded if they had denied access to their medical records for research purposes. The medical records were reviewed, and patients were excluded if they had a ‘thick’ melanoma (Breslow depth >4 mm; T classification T4). The following four variables were used to identify lesions of sufficient risk for inclusion: Breslow depth, presence of ulceration, mitotic rate >0 and age <40 years. A patient was included if i) Breslow depth >1 to <4 mm, or ii) Breslow depth between 0.75 and <1 mm with 1 or more of the other 3 risk factors, or iii) Breslow depth between 0.50 and <0.75 mm with 2 or more of the other 3 risk factors. Patients with ambiguous pathology or SLN biopsy findings were also excluded. The tissue blocks were reviewed, and patients were excluded if i) the blocks were not retrievable, or ii) sufficient material was not dispensable for research, or iii) only partial primary biopsy samples were available (i.e. biopsies with <80% of total Breslow depth), or iv) available tissue was limited to re-excision specimens in lieu of the original biopsy, or v) the quality of retrievable RNA was poor.
Model Validation CohortThe model validation cohort consisted of patients who met the same criteria as described for the model development cohort. These patients had a SLN biopsy performed within 90 days of their diagnosis at either Mayo Clinic Rochester or Mayo Clinic Florida.
Data CollectionThe following demographic, diagnosis, and pathologic information was abstracted from the medical record: gender, date of birth, date of malignant melanoma diagnosis, date of SLN biopsy, SLN biopsy finding, Breslow depth, mitotic rate (absent, 1-6, >6) presence of ulceration, presence of tumor invading lymphocytes, and presence of angiolymphatic invasion. For analysis purposes, Breslow depth was categorized using recent AJCC guidelines (Balch et al., J. Clin. Oncol., 27:6199 (2009)).
Block ProcessingAll tissue used was routinely processed, formalin-fixed and paraffin-embedded (FFPE). Preferred starting material for RNA purification was from freshly cut sections of FFPE tissue, each with a thickness of 20 μm. If a tissue was available only as unstained sections mounted on glass slides, RNA retrieval was attempted but typically yielded lower concentrations and poorer quality.
Microfluidic RT-PCRThe Fluidigm BioMark HD System was used for quantitative RT-PCR using EvaGreen DNA binding dye (Biotium) and 96.96 dynamic array integrated fluid circuits (Fluidigm). 77 specific targets in 62 genes (54 experimental and 8 control genes) were amplified per cDNA (standards, controls and experimental samples). Genes included: house-keeping (ACTB, RPLP0, RPL8), melanocyte lineage (MLANA, MITF, TYR, PMEL), basal keratinocyte lineage (KRT14), integrin cell adhesion receptors (ITGB1, ITGB3, ITGA2, ITGA3, ITGA5, ITGAV), integrin trafficking (SNX17, SNX31), fibronectin-related (FN1, THBS1, THBS2, THBS4, SPP1, PLAT, TNC, SPARC, POSTN, FBLN2, DSPP1), collagen-related (COL1A1, COL4A1, COL18A1, PLOD1, PLOD2, PLOD3, LOX, LOXL1, LOXL3, PCOLCE, PCOLCE2), laminins (LAMA1, LAMB1, LAMC1, LAMA3, LAMB3, LAMC2), other extracellular matrix (AGRN, VCAN, GDF15, BGAN, CTGF, CYR61, CSF2, CXCL1, CCL2, IL8, IL6), adhesion signaling (PTK2, CSRC), and cell cycle (CDKN1A, CDKN2A, TP53, YAP, TAZ). The following cDNA were run per array: standards, i.e. linearized cDNA mixes of targets ranging from 5 to 500,000 in copy number and prepared as 1:10 dilutions (a total of 6 standards), run in triplicates; control cDNA (nevi and melanoma metastases); experimental cDNA; the latter two were in duplicates. All cDNA was pre-amplified in a 14 cycle reaction (TaqMan Preamp Master Mix, Applied Biosystems). Array-based quantitative PCR was with the help of the TaqMan Gene Expression Master Mix (Applied Biosystems). After thermal cycling, raw Ct data was exported for further analysis. Standards were checked for linear amplification, i.e. a drop in Ct value by approximately log2 10 per 1:10 dilution. Copy numbers for negative and positive controls were normalized to 25,000 copies of total housekeeping genes. Averaged, normalized gene copy numbers were compared to an internal standard for inter-experiment variation. Data from arrays that did not pass both linear amplification and reproducibility checks were discarded.
To account for sample contamination from keratinocyte-derived RNA, the gene copy number of KRT14, a basal keratinocyte marker, was determined. This number was multiplied with a gene-specific contamination factor, i.e. a value of gene copy number contamination per copy of KRT14. Expression profiling of normal skin devoid of melanocyte nests was performed to establish a contamination factor. The calculated number of keratinocyte-derived RNA contamination was then deducted from the averaged, normalized gene copy number. The final averaged, normalized and background-corrected gene copy number was used for further analysis.
To assess for melanocyte content, at least two melanocyte lineage markers were amplified: MLANA and MITF. Sufficient melanocyte content was assumed if the sum of their averaged, normalized and background-corrected copy numbers was 1,000. If this was not the case, presence of melanocytic tumor had to be confirmed on tissue recuts followed by histologic review. Samples from tissue blocks exhausted of tumor were discarded. Expression data from samples that passed all quality controls were combined with pathology and clinical data and used for statistical modeling.
Chemicals, Antibodies and cDNA
Isopropyl β-D-1-thiogalactopyranoside (IPTG), 4′,6-Diamidino-2-phenylindole dihydrochloridemitomycin (DAPI), blebbistatin and PF-573228 were purchased from Sigma-Aldrich. Dabrafenib (GSK2118436) was purchased from Selleckchem. FAK antibody (06-543) was from EMD Millipore. FAK pY397 (44624G) antibody was from Life Technologies. Total ERK (9102) and phospho-ERK (4370) antibodies were from Cell Signaling. Paxillin (610051), ITGB3 (555754), ITGB1 (555443) and mouse IgG1 kappa (555749) antibodies were from BD Transduction Labs. Drugs were used at 5 μM final concentration. EGFP control cDNA was from (Lonza). FAK cDNA was obtained from A. Huttenlocher, Addgene plasmid number 35039 (Chan et al., J. Biol. Chem., 285:11418-26 (2010)).
Cell LinesWM858 were purchased from the Meenhard Herlyn lab (Wistar Institute). WM278 and WM1617 lines were purchased from Coriell Cell Repositories. KN lines were isolated from lymph node metastases using a gentle MACS dissociator and tumor dissociation kit (Miltenyi Biotec). WM and KN lines were propagated exclusively in vitro. M lines were isolated from melanoma brain metastases using previously described methods (Carlson et al., Curr. Prot. Pharmacology, 14.6.1-14.6. 23 (2011)). Some M lines were propagated in mice. Cells were cultured in vitro using DermaLife M Medium (Lifeline Cell Technology).
Generation of IPTG-Inducible FAK shRNA Cells
Five TRC clones were cloned into the pLKO-puro-IPTG-1XLacO vector. The same vector format was used for the non-target negative control (NC) shRNA SHC312V (Sigma-Aldrich). TRC identifiers were as follows: TRCN0000121207, TRCN0000121318, TRCN0000121129, TRCN0000194984, and TRCN0000196310. Lentivirus was produced for each TRC clone and multiple pools of WM858 cells were transduced per clone. The first three TRC sequences did not induce significant FAK knockdown in WM858 cells. The latter two (abbreviated as shRNA 841 and 102) were effective and used for experiments. Selection of successfully transduced cells was with puromycin (Sigma-Aldrich).
Focal Adhesion Visualization on Fibronectin MicropatternsCells were plated on micropatterned disks of fluorescent fibronectin surrounded by a cytophobic surface (CYTOO). Cells were allowed to adhere for 1 hour in serum-free medium, and then were fixed and incubated with anti-paxillin antibody followed by a fluorescent secondary antibody and DAPI. Images of fluorescent cells were obtained with a laser scanning confocal microscope (Zeiss LSM780). Max intensity overlays of 15 representative cells per cell type were generated using a plug-in ImageJ macro from CYTOO.
Cell ProliferationAutomated quantification of cell proliferation was by the IncuCyte™ kinetic imaging system (Essen Bioscience). Approximately 2,000 cells were seeded into a 96 well cell culture dish, 8 replicates per condition over the indicated time. Data analysis was with the IncuCyte ZOOM software package.
Western Blotting by Protein SimpleWestern blotting was by standard techniques or automated with a Wes device from ProteinSimple. The automated work-flow was according to the manufacturer's instructions. Image analysis was with the ProteinSimple Compass software.
Gene Expression by Next-Generation SequencingSequencing of FFPE-derived RNA was performed using standard methods. Briefly, RNA-derived cDNA libraries were prepared using the NuGen Ovation® RNAseq FFPE library system. Concentration and size distribution of the resulting libraries were determined on an Agilent Bioanalyzer DNA 1000 chip and confirmed by Qubit fluorometry (Life Technologies, Grand Island, N.Y.). Unique indexes were incorporated at the adaptor ligation phase for 3-plex sample loading. Libraries were loaded onto paired end flow cells to generate cluster densities of 700,000/mm2 following Illumina's standard protocol. The flow cells were sequenced as 51×2 paired end reads on an Illumina HiSeq 2000. For differential gene expression analysis, the edgeR bioconductor software package (http://bioconductor.org) was used. Because scaling by total lane counts (e.g., by the ‘reads per kilobase of exon model per million mapped reads’ (RPKM) method) can bias estimates of differential expression, quantile-based normalization was used on read counts to determine if genes are differentially expressed (Bullard et al., BMC bioinformatics, 11:94 (2010)) using the negative binomial method (Anders and Huber, Genome Biol., 11:R106 (2010)) requiring an adjusted p-value of <0.01 controlled for multiple testing using the Benjamini and Hochberg correction.
Statistical Methods Model DevelopmentThe primary outcome measure for this study is a positive SLN within 90 days of the primary melanoma diagnosis. Clinical and pathologic characteristics were evaluated univariately for an association with SLN positivity using the chi-square test for categorical variables and the two-sample t-test for continuous variables. A prediction model was constructed from these characteristics using multivariable logistic regression. Associations were summarized using the odds ratio (OR) and corresponding 95% confidence intervals (CI) derived from the model estimates.
When evaluating gene expression data as potential predictors of outcomes, it is useful to model interactions between the genes. Logic regression can be used to discover and model interactions of binary explanatory variables, and combinations are created using Boolean operators (‘and’, ‘or’ and ‘not’) (Ruczinski et al., J. Comput. Graph. Stat., 12:475-511 (2003)). Since logic regression is limited to using binary explanatory variables, reasonable cutoff values needed to be established for each of the 54 experimental genes. For each gene, a separate Classification and Regression Tree (CART) model was fit to identify the best gene expression cutoffs to differentiate between patients with positive and negative SLN using the Gini rule for splitting, prior probabilities proportional to the observed data frequencies, and 0/1 losses. The AUC for these models ranged from 0.50 to 0.781. A total of 147 binary variables were created using all the breakpoints generated by the CART models and these breakpoints were then used to fit the logic regression.
Receiver operating characteristic (ROC) curves were constructed for the final prediction models. The predictive ability of each model was summarized by the area under curve (AUC), and the AUC estimates were compared between models using the DeLong, DeLong, and Clarke-Pearson non-parametric method for comparing the AUC for correlated ROC curves.
Model ValidationThe performance of the prognostic model developed using the development cohort was validated in a new cohort by assessing the discrimination and calibration. Discrimination was assessed by quantifying the model's ability to discriminate between patients in the new cohort who do and do not have a positive SLNB using the area under the ROC curve. Calibration was assessed by grouping patients into 5 quintiles based on their predicted probabilities estimated by the model and comparing the median predicted probability in each quintile with the observed proportion of patients with a positive SNLB in that quintile.
The statistical analysis was performed SAS version 9.2 and R version 3.0.1. The CART analysis was performed using the rpart package (rpart: Recursive Partitioning. http://CRAN.R-project.org/package=rpart. Version 4.1-1; Therneau and Atkinson. An introduction to recursive partitioning using the RPART routines: Technical Report 61, Section of Biostatistics, Mayo Clinic, Rochester). The logic regression used LogicReg package (LogicReg: Logic Regression. http://CRAN.R-project.org/package=LogicReg. Version 1.5.5; Ruczinski et al., J. Comput. Graph. Stat., 12:475-511 (2003)).
Logic Regression Logic regression fits regression models using 1 to 5 trees, and the trees can be composed of many leaves. Simulated annealing was used to explore possible logic regression models to find a good model. The technique starts by fitting a model built randomly using a specified number of leaves and trees. A new model is created by randomly permuting the current model by changing a leaf or Boolean operator. The performance of the current model is then compared to the new model. If the new model performs better, then it becomes the current model, and the process is repeated. Simulated annealing avoids local optima by controlling when inferior models were chosen. The null model randomization test was used to determine if there was a relationship between the 147 binary gene expression variables and SLN positivity. The optimal number of leafs and trees was determined using cross validation and permutation techniques.
The null model randomization test was used to determine if there was a relationship between the 147 binary gene expression variables and SLN positivity. First, the best model was fit for all biopsy samples using logic regression. Next, the SLN positivity outcome for all the patients was randomly reassigned and fit another model. The process of randomly reassigning the SLN positivity outcome and fitting a model was performed 25 times.
The optimal number of leafs and trees in the logic regression model was determined using cross validation and permutation techniques. Ten-fold cross validation was used to help determine the ideal model size given the data.
(PLAT >427)).
Results
This investigation started by identifying functional networks of differentially expressed genes in benign melanocytic lesions vs. invasive melanoma. In a pilot study, three patients with benign nevi were age and gender-matched one-to-one to a patient with a primary skin melanoma that had metastasized regionally. A total of 15,413 genes were identified and measured by next-generation sequencing (NGS) of patient biopsy-derived RNA. Differential gene expression analysis yielded 160 genes with a false-discovery rate (FDR)<0.01. These were entered into the STRING database to identify functional gene networks. Genes that were without known functional relationships to other genes were hidden. Two clusters with more than two nodes emerged; the largest was linked to integrin cell adhesion (
Next, the objective was to confirm that genes involved in integrin cell adhesion are up-regulated in invasive melanoma. A test set of 73 benign nevi (53 were without histological atypia, 7 were with mild, 11 with moderate and 2 with severe atypia), 38 primary skin melanoma that had metastasized regionally (median Breslow depth of 3 mm; IQR, 2 to 4 mm), and 11 in-transit regional melanoma metastases was assembled. A method for determining copy number of 77 specific targets in 62 genes (54 experimental and 8 control genes) by quantitative PCR was established as described herein. Genes were categorized as follows: i) integrin adhesion receptor subunits; ii) FN1 and related extracellular matrix (ECM) components; iii) collagen genes and enzymes that facilitate the cross-linking of collagens; iv) laminin subunits; v) other ECM components including those of a pro-inflammatory DNA damage response (Coppe et al., PLoS biology, 6:e301 (2008)); vi) integrin-activated kinases, and vii) cell cycle related. Genes with significant regulation between benign and malignant were mainly in the categories of integrins and FN1 and related ECM components, thus confirming NGS results (
The following was performed to assess whether adhesion gene expression in tissue sections predicted metastasis to SLN and to determine whether the method outperformed the current clinical gold standard for predicting metastasis risk, i.e. Breslow invasion depth (Breslow, Annals of Surg., 172:902 (1970)). The model development cohort consisted of a total of 360 thin and intermediate thickness primary melanoma (Breslow depth ≦4 mm) of all histologic types with a SLN biopsy within 90 days of their diagnosis (Table 14). To exclude minimal risk lesions, thin melanoma (Breslow depth <1 mm; T classification 1) without additional risk factors (ulceration, mitoses, patient age <40) were not considered. Thick melanoma (Breslow depth >4 mm; T classification 4) were excluded because they frequently metastasize to SLN and the clinical utility of a molecular test is low.
Table 15 summarizes the clinical and pathologic factors that were evaluated univariately for an association with SLN positivity. Ulceration, Breslow depth, and age were identified as independently associated with SLN positivity (Table 16, Model A). Logic regression models were fit utilizing 147 binary variables derived from 54 experimental genes and evaluated using the breakpoints generated by the CART models for the 54 genes. The best 4 leaf model considered 3 integrin (ITGB3), cellular tumor antigen p53 (TP53), the laminin B1 chain (LAMB1), and tissue-type plasminogen activator (PLAT). SLN positivity within each of these 4 categories is summarized at the bottom of Table 15. The model results for a combined model including both the clinical/pathologic factors and the gene expression parameters are presented as model B in Table 16.
It was subsequently decided to collapse the four categories in the gene model into two categories which yielded a simpler model without loss of overall predictive ability (Table 16, model C). The receiver operating characteristic (ROC) curves for the three models are displayed in
The model validation cohort included 104 patients. Table 17 summarizes the association of the clinical and pathologic factors with SLN positivity, separately for the two cohorts. The discriminative ability of the predictive model was excellent when applied to the validation cohort (AUC 0.92, 95% CI 0.87-0.97). Table 18 compares the predicted and observed rate of positive SLNB for the 5 quintiles defined by the distribution of the predicted probabilities. The two rates track consistently across the 5 quintiles suggesting reasonable calibration.
The following was performed to determine whether the expression of (33 integrin and other adhesion-related genes in melanoma is influenced by focal adhesion kinase (FAK), a key transducer of integrin signals and novel cancer therapy target (Infante et al., J. Clin. Oncol., 30:1527-33 (2012)). To test whether FAK controls adhesion gene expression, B-rafV600E WM858 cells were engineered to contain IPTG-inducible short hairpin RNA (shRNA) against FAK. FAK knock-down was highly effective at the RNA and protein level at concentrations equal to or exceeding 0.025 mM IPTG (
As described herein, a completely customizable high-density microfluidic PCR platform was used to allow for the quantification of multiple genes by repeat measurements. For example, at least 26 individual PCR reactions were performed per patient sample to measure house-keeping genes. To account for RNA contamination by basal keratinocytes—a cell type with stem cell-like features and high levels of adhesion gene expression—keratin 14 (KRT14), a basal keratinocyte marker, was quantified. KRT14 copy number was multiplied with a gene specific, per-copy-of-KRT14 contamination factor that was pre-determined by analyzing normal skin; and the product of this calculation was used to correct for keratinocyte background. In addition, melanocyte markers were routinely assayed to quantify melanocyte content in processed tissue. Aside from throughput, the methods provided herein have several other advantages. First, they are quantitative. This is an advantage over IHC or fluorescent in-situ hybridization (FISH), where the signal intensity is difficult to normalize and/or image analysis is subjective and time consuming. Second, they are based on the quantitation of RNA, which in contrast to DNA carries epigenetic information. Third, they are devoid of array-based hybridization steps which can lead to hybridization errors and noise. Fourth, they are easily adjusted to include additional genes of interest.
The results provided herein demonstrate that the best 4 leaf molecular model for predicting SLN metastasis considered β3 integrin, the laminin B1 chain, tissue-type plasminogen activator and tumor antigen p53. The overall predictive ability of a combined model that included molecular parameters was significantly greater than a model that only included clinical/pathologic factors (0.89 vs. 0.77, p<0.001).
The results provided herein also demonstrate that FAK inhibition induces the expression of integrins, induces the size of focal adhesions, and stimulates proliferation and mitogen activated kinases. These effects were strongest in B-rafV600E cells, likely because mutant B-raf inhibits FAK to trigger integrin expression.
The 2-tree 2-leaf model was generated using logic regression and slow cooling on simulated annealing parameters.
Additional analysis of samples by next generation sequencing using a cohort of four patients with primary skin melanoma that had not metastasized (median Breslow depth: 2.6 mm) and three patients that had metastasized regionally (median Breslow depth: 2.3 mm) yielded a total of 208 differentially regulated genes out of a total of 15,196 measured genes. ITGB3 as well as SRC, a key downstream effector of β3 integrin, formed the center of a functional network deregulated in regionally metastatic vs. non-metastatic melanoma (
Expanding the sample size of the model validation cohort from 104 to 146 resulted in excellent discriminative ability of the clinicopathologic+molecular model with an AUC of 0.93, 95% CI 0.87-0.97 (
Osteopontin (SPP1) is a proto-typical cancer-associated extracellular matrix gene and ligand of αv and α5β1 integrins. SPP1 is highly overexpressed in melanoma (Talantov et al., Clin. Cancer Res., 11:7234-42 (2005)) and its upregulation correlates with metastasis risk (Conway et al., Clin. Cancer Res., 15:6939-6946 (2009) and Mitra et al., Br. J. Cancer, 103:1229-1236 (2010)). To rapidly screen chemical compounds for their ability to inhibit SPP1 expression in vitro, the endogenous SPP1 promoter of WM858 melanoma cells was tagged with a dual luciferase system using zinc finger nucleases. The SPP1-promoter drives firefly luciferase tagged with a protein degradation sequence (hPEST). A CMV-promoter driven renilla luciferase was used as a loading control (
The investigation was started by screening a 1280 compound library of pharmaceutically active compounds (LOPAC; Sigma-Aldrich). The firefly signal was first normalized to the renilla signal, then to DMSO-treated control wells (
Pentamidine exhibited little cytotoxicity in WM858 and M12 cells with ED50's >100 μM (M12 cells are metastatic B-rafV600E melanoma cells that were recently established from a patient). Pentamidine inhibited SPP1 mRNA in both WM858 (
To determine whether Pentamidine reduces SPP1 expression in vivo, M12 cells were injected intradermally into female nude mice and left to grow until xenograft tumors formed (
These results demonstrate that pentamidine can be used to reduce the expression of ITGB3, PLAT, and SPP1.
OTHER EMBODIMENTSIt is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.
Claims
1. A method for identifying a metastatic malignant skin lesion, wherein said method comprises:
- (a) determining, within a test sample, the expression level of a marker gene selected from the group consisting of PLAT, ITGB3, LAMB1, and TP53 to obtain a measured expression level of said marker gene for said test sample,
- (b) determining, within said test sample, the expression level of a keratinocyte marker gene to obtain a measured expression level of said keratinocyte marker gene for said test sample,
- (c) removing, from said measured expression level of said marker gene for said test sample, a level of expression attributable to keratinocytes present in said test sample using said measured expression level of said keratinocyte marker gene for said test sample and a keratinocyte correction factor to obtain a corrected value of marker gene expression for said test sample, and
- (d) identifying said test sample as containing a metastatic malignant skin lesion based, at least in part, on said corrected value of marker gene expression for said test sample.
2. The method of claim 1, wherein said keratinocyte marker gene is K14.
3. The method of claim 1, wherein said marker gene is PLAT or ITGB3.
4. The method of claim 1, wherein step (c) comprises (i) multiplying said measured expression level of said keratinocyte marker gene for said test sample by said keratinocyte correction factor to obtain a correction value and (ii) subtracting said correction value from said measured expression level of said marker gene for said test sample to obtain said corrected value of marker gene expression for said test sample.
5. The method of claim 1, wherein said method comprises determining, within said test sample, the expression level of at least two marker genes selected from the group consisting of PLAT, ITGB3, LAMB1, and TP53 to obtain measured expression levels of said at least two marker genes for said test sample.
6. The method of claim 1, wherein said method comprises determining, within said test sample, the expression level of at least three marker genes selected from the group consisting of PLAT, ITGB3, LAMB1, and TP53 to obtain measured expression levels of said at least three marker genes for said test sample.
7. The method of claim 1, wherein said method comprises determining, within said test sample, the expression level of PLAT, ITGB3, LAMB1, and TP53 to obtain measured expression levels of said PLAT, ITGB3, LAMB1, and TP53 for said test sample.
8. A kit for identifying a metastatic malignant skin lesion, wherein said kit comprises:
- (a) a primer pair for determining, within a test sample, the expression level of a marker gene selected from the group consisting of LAMB1 and TP53 to obtain a measured expression level of said marker gene for said test sample, and
- (b) a primer pair for determining, within said test sample, the expression level of a keratinocyte marker gene to obtain a measured expression level of said keratinocyte marker gene for said test sample.
9. The kit of claim 8, wherein said keratinocyte marker gene is K14.
10. The kit of claim 8, wherein said marker gene is LAMB1.
11. The kit of claim 8, wherein said marker gene is TP53.
12. The kit of claim 8, wherein said kit comprises primer pairs for determining, within said test sample, the expression level of LAMB1 and TP53 to obtain measured expression levels of said LAMB1 and TP53 for said test sample.
13. The kit of claim 8, wherein said kit comprises primer pairs for determining, within said test sample, the expression level of PLAT to obtain measured expression levels of said PLAT for said test sample.
14. The kit of claim 8, wherein said kit comprises primer pairs for determining, within said test sample, the expression level of ITGB3 to obtain measured expression levels of said ITGB3 for said test sample.
15. The kit of claim 8, wherein said kit comprises primer pairs for determining, within said test sample, the expression level of PLAT and ITGB3 to obtain measured expression levels of said ITGB3 and PLAT for said test sample.
16. A method for identifying a metastatic malignant skin lesion, wherein said method comprises:
- (a) determining, within a test sample, the expression level of a marker gene selected from the group consisting of PLAT, ITGB3, LAMB1, and TP53 to obtain a measured expression level of said marker gene for said test sample,
- (b) determining, within said test sample, the expression level of a keratinocyte marker gene to obtain a measured expression level of said keratinocyte marker gene for said test sample,
- (c) removing, from said measured expression level of said marker gene for said test sample, a level of expression attributable to keratinocytes present in said test sample using said measured expression level of said keratinocyte marker gene for said test sample and a keratinocyte correction factor to obtain a corrected value of marker gene expression for said test sample, and
- (d) identifying said test sample as containing a metastatic malignant skin lesion based, at least in part, on said corrected value of marker gene expression for said test sample.
17. The method of claim 16, wherein said keratinocyte marker gene is K14.
18. The method of claim 16, wherein said marker gene is LAMB1 or TP53.
19. The method of claim 16, wherein step (c) comprises (i) multiplying said measured expression level of said keratinocyte marker gene for said test sample by said keratinocyte correction factor to obtain a correction value and (ii) subtracting said correction value from said measured expression level of said marker gene for said test sample to obtain said corrected value of marker gene expression for said test sample.
20-29. (canceled)
Type: Application
Filed: Aug 13, 2015
Publication Date: Sep 28, 2017
Applicant: Mayo Foundation for Medical Education and Research (Rochester, MN)
Inventors: Alexander Meves (Rochester, MN), Ekaterina M. Nikolova (Rochester, MN)
Application Number: 15/503,973
