REGULATION OF PROLIFERATION AND PRODUCTION OF PROSTATE-SPECIFIC ANTIGEN IN ANDROGEN-SENSITIVE PROSTATIC-CANCER CELLS, LNCAP, BY DIHYDROTESTOSTERONE

LNCaP is an androgen-sensitive human prostatic cancer cell line. The e ffect of androgen on these cells is characterized by a bell-shaped gro wth response and a dose-dependent induction of prostate-specific antig en (PSA) production. The present study was carried out to gain further insight into the effect of androgen on LNCaP. Cells were cultured in phenol red-free RPMI-1640 supplemented with 10% charcoal-stripped feta l bovine serum, with concentrations of dihydrotestosterone (DHT) rangi ng from 0-10(-7) M, in a 4-day culture system. A bell-shaped growth re sponse was reproduced with a peak level of cell count at 10(-10) M DHT . PSA secretion from these cells did not increase significantly until the DHT level in the medium reached 10(-9) M. A progressive increase i n PSA secretion was observed at higher DHT concentrations accompanied with a progressive decline in cellular proliferation. The results of i mmunocytochemical analysis of PSA localization indicated that the prop ortion of cells with positive staining for PSA also increased with inc reasing concentrations of DHT. Analysis of androgen receptors, as dete rmined by both immunocytochemistry and Western blot analysis, showed a decline in nuclear androgen receptor at low concentrations of DHT and an increase in the amount of receptor protein at high concentrations. These results indicated that the androgen-induced bell-shaped growth response in LNCaP cells represented the manifestation of two different cellular events in dose-related manner: cellular proliferation at low DHT concentrations and increased production of PSA at high DHT concen trations.