ENHANCED ANDROGEN SENSITIVITY IN SERUM-FREE MEDIUM OF A SUBLINE OF THE LNCAP HUMAN PROSTATE-CANCER CELL-LINE

The LNCaP-Fast Growing Colony (FGC) human prostate cancer cell line pr oliferates in response to the addition of dihydrotestosterone (DHT) 10 (-10)-10(-8) M in charcoal-stripped serum-supplemented media. LNCaP-FG C cells will not attach or proliferate in serum-free conditions. LNCaP -FGC stock cultures were maintained in medium supplemented with 10% FB S and added DHT (10(-9) M) for >25 passages (6 months). The resultant subline was designated as LNCaP-ss (supersensitive) because of its abi lity to attach in serum-free medium and to proliferate in response to very low levels of DHT. LNCaP-ss cells were grown in serum-free medium and proliferation assessed after 2, 3, 5, and 7 days' treatment with DHT. Significant enhancement of growth was demonstrated after 7 days' treatment with DHT over a wide range of concentrations (DHT 10(-15)-10 (-7) M) with maximal stimulation (3 x control, p < .001) noted with DH T 10(-14) M. Changing the medium during the course of the experiment d ecreased, but did not eliminate, the DHT-induced cellular proliferatio n. Scatchard analysis of binding studies with LNCaP-ss cells revealed that both the K(d) for the androgen receptor (AR) and the number of AR sites/cell were similar to the corresponding values reported for the parental line. AR mRNA levels in LNCaP-ss cells, as measured by RNase protection assay, were significantly down-regulated by 7 days' treatme nt with DHT 10(-15), 10(-13), and 10(-9) M. We conclude that maintaini ng LNCaP-FGC cells for 6 months in medium supplemented with DHT result ed in the development of a subline, LNCaP-ss, which can attach and pro liferate in serum-free medium. This subline is sensitive to very low l evels of androgen, as evidenced by increased proliferation and down-re gulation of AR mRNA levels.