Rat prostate cancer cell line-specific production and apparent secretion of heparin-binding growth factors

Cultured C3 and T5 AXC/SSh rat prostate cancer cells and their conditioned media contained 1000-fold more heparin-binding mitogens than did normal AXC/SSh rat prostates. Immunological analyses confirmed that rat ventral prostate contained only a 17.5 kilodalton (kDa) basic fibroblast growth factor (bFGF)-like mitogen. In contrast, combined immunological and metabolic radiolabeling analyses showed that C3 cells contained 23/24 and 14 kDa bFGF-like polypeptides, whereas the principal bFGF-like polypeptides of C3 cell conditioned medium were proteins having masses of 17.5 and 14 kDa. Identical analyses showed that T5 cells contained 17.5 and 14 kDa bFGF-like polypeptides, whereas the principal bFGF-like polypeptides of T5 cell conditioned medium were proteins having masses of 17.5, 16, and 14 kDa. We found that bFGF-like proteins of mass less than 17.5 kDa, which were present in conditioned medium, were not derived by proteolysis of higher molecular weight bFGF-like mitogens after these were processed into conditioned medium. Northern analyses showed that normal prostate and prostate cancer cells contained acidic fibroblast growth factor transcripts of 6.5 and 3.4 kilobases (kb) and bFGF transcripts of 6.0 and 2.5 kb. Prostate cancer cells also contained a 12-kb bFGF transcript that was not present in normal prostate. Southern analysis of restriction endonuclease-digested normal prostate or prostate cancer cell genomic DNA showed that the 12-kb bFGF transcript was not the product of a rearranged bFGF gene. Our data show that rat prostate cancer cells contain bFGF-like polypeptides of mass 14 to 23/24 kDa and suggest that these cells secrete bFGF-like polypeptides.