Abstract: The invention relates to the establishment of expression vectors replicable in a mammalian cell, including a DNA sequence encoding human prosaposin (PSAP) or Saposin C, operably linked with regulatory DNA capable of effecting the expression of the PSAP and Saposin C DNA coding sequence in the cells. In addition, the invention relates to mammalian cells (CHO-K1) stably transfected with such expression vectors and methods of producing human Saposin C or PSAP, including transfecting a mammalian cell with expression vectors, maintaining and propagating the cell in culture medium, and isolating soluble rh-Saposin C or rh-PSAP from the medium. Purified rh-Saposin C and rh-PSAP are useful as reagents for studying biological responses and signal transduction mechanism in benign or malignant cells, as standard proteins in diagnosis or screening of benign or malignant diseases, or as medicine for the treatment of diseases or disorders affecting musculoskeletal system or peripheral and central nervous system.

Abstract: Saposin C was shown to be a trophic factor for a variety of cancer cells, e.g., prostate, lung, breast, and colon cancer cells. These cells expressed saposin C and responded to saposin C by increased levels of cell proliferation, cell migration, and cell invasion. Such activities typify and promote the neoplastic process. For prostate cancer, the androgen-insensitive prostate cancer cells responded to saposin C by higher levels of cell proliferation, cell migration and cell invasion than did the androgen-sensitive prostate cells. Stromal cells (from the prostate) were also responsive to saposin C-mediated signals in a manner typical of growth promoting compounds. The androgen-insensitive prostate cells were stimulated by saposin C to express higher levels of the urokinase plasminogen activator (uPA) and its receptor (uPAR), two proteins known to be involved in cell invasion.

Abstract: Saposin C was shown to be a trophic factor for a variety of cancer cells, e.g., prostate, lung, breast, and colon cancer cells. These cells expressed saposin C and responded to saposin C by increased levels of cell proliferation, cell migration, and cell invasion. Such activities typify and promote the neoplastic process. For prostate cancer, the androgen-insensitive prostate cancer cells responded to saposin C by higher levels of cell proliferation, cell migration and cell invasion than did the androgen-sensitive prostate cells. Stromal cells (from the prostate) were also responsive to saposin C-mediated signals in a manner typical of growth promoting compounds. The androgen-insensitive prostate cells were stimulated by saposin C to express higher levels of the urokinase plasminogen activator (uPA) and its receptor (uPAR), two proteins known to be involved in cell invasion.