Abstract: The invention features methods of diagnosing cancer in a mammal (e.g., a human) by detecting a biomarker selected from a satellite II ribonucleic acid (RNA) molecule, a cancer-associated polycomb group (CAP) body, a cancer-associated satellite transcript (CAST) body, and UbH2A. Also featured is a method for identifying an agent for treating cancer in a mammal by contacting a cancer cell having a biomarker selected from a CAP body, a CAST body, and a satellite II RNA molecule with a test agent and determining whether the test agent reduces the level of the biomarker in the cancer cell. Other inventions featured are a method for determining whether a chemotherapeutic agent increases epigenetic imbalance of a cell and a method for detecting epigenetic imbalance by determining a copy number of a satellite II DNA locus at chromosome 1q12 in a cell.

Abstract: The compositions and methods described herein are based, at least in part, on fundamental observations concerning nuclear organization and gene expression. More specifically, the studies described below have revealed a new type of nuclear body or intra-nuclear organelle, which is referred to herein as a PAN body (an acronym for PML body adjacent nuclear body). The evidence collected to date supports a role for PAN bodies in nuclear function, gene regulation (or expression), and disease. For example, the studies reveal a structural relationship between PAN bodies and PML bodies, which are implicated in cell proliferation and apoptosis. This relationship and others are discussed further below. Accordingly, the invention features isolated or purified PAN bodies and therapeutic (including prophylactic), diagnostic, and screening methods that utilize PAN bodies.