SOLUBLE FORMS OF CD44 AND CD54 (ICAM-1) CELLULAR ADHESION MOLECULES ARE RELEASED BY HUMAN PROSTATIC-CANCER CELL-LINES

We have identified that human prostatic cancer cell lines DU145, PC3, ND1, ALVA31 and JCA1 released soluble CD44 molecules and DU145, PC3 an d ND1 released soluble CD54. Both soluble and surface CD44 were not fo und in LNCaP, and both forms of CD54 were not expressed in LNCaP and J CA1. CD54 was found to be highly expressed on cell surface in ALVA31, but these cells did not release soluble CD54. Expression of both cell surface and soluble forms were examined after treatment of cells with IFN-gamma, TGF-beta 1, or culturing in serum-free media. The concentra tion of soluble CD54 in supernatants changed to small extent after tre atment with TGF-beta 1 and increased after treatment with IFN-gamma or in serum-free media. Cell surface expression of CD54 however, changed only minimally after treatment. The levels of cell surface and solubl e CD44 also changed minimally after treatment with IFN-gamma and TGF-b eta 1 but decreased in serum-free media and this was accompanied by ma rked elevation of soluble CD44 in supernatants. These data indicate th at soluble CD44 might be released from cell surface by shedding wherea s alternative splicing is the most likely mechanism of soluble CD54 re lease.