APOPTOTIC PROGRAM IS INITIATED BUT NOT COMPLETED IN LNCAP CELLS IN RESPONSE TO GROWTH IN CHARCOAL-STRIPPED MEDIA

BACKGROUND. Morphological, proliferative, and gene,tic changes were st udied in androgen-responsive LNCaP cells in response to growth in char coal-stripped (CS) media. METHODS AND RESULTS. Within 5 days of treatm ent, there were dramatic changes in the morphology and organization of LNCaP cells. The cells unclumped and acquired a distinct neuronal-lik e appearance with small cell bodies and multiple long, thin processes. Despite this appearance, the cells stained negative to monoclonal ant ibodies to neuronal markers such as microtubule-associated protein-2 ( MAP-2) and glial fibrillary acidic protein (GFAP). In situ end-labelin g assay indicated that the number of cells showing signs of apoptosis (DNA fragmentation) increased dramatically in CS media compared to the control. However, ultrastructural changes and the fragmented DNA ladd er that are used to define apoptosis were not observed. Instead of cel l death, the cells became cytostatic, which can be reversed, although not completely, by exogeneous addition of dihydrotestosterone in a dos e-dependent manner. Presence of mRNA of several genes involved in the apoptotic process, i.e., Bcl-2, Bcl-X, ICE, Ich-1, and DAD-1, was stud ied in response to normal and CS media. We detected mRNA of Bcl-2, Bcl -X-L, Bcl-X-S, Ich-1(L) and DAD-1, while ICE and Ich-1(S) were not exp ressed in LNCaP cells. CONCLUSIONS. This suggests that certain signals that may be essential for complete execution of the apoptotic program may be missing in this in vitro model. This may explain our observati on that the growth of LNCaP cells in CS media does not fully mimic cas tration-mediated regression of the prostate gland in vivo. (C) 1997 Wi ley-Liss, Inc.