Androgen Regulation of HBGF-I (aFGF) mRNA and Characferization of the Androgen-Receptor mRNA in the Human Prostate Carcinoma Cell Line-LNCaP/A-Dep

Summary

A low serum media was developed for growing LNCaP/A-dep cells. It was demonstrated that testosterone at 10^-9M can stimulate growth 5-fold. The anti-androgens, cyproterone acetate and hydroxyflutamide, also stimulates growth of LNCaP/A-dep cells at an optimum concentration of 10^-7M. Estradiol 17β stimulates growth at an optimum concentration of 10^-8M. Both aFGF/HBGF-I and EGF have an additive affect on growth when added together with androgen, anti-androgens or estrogen. By Northern analysis and in situ hybridization the steady state level of aFGF/HBGF-I mRNA is increased 5-20 x after a 72 hr to 5 day treatment with testosterone (10^-8M), RI881 (10^-8M) or estradiol 17β, either in the presence or absence of EGF. A cDNA to LNCaP/A-dep aFGF /HBGF-I mRNA was isolated and shown to be identical to the normal human aFGF /HBGF-I in the coding region. The unusual positive growth response of LNCaP/Adep cells to anti-androgens and estradiol-17β suggested that the androgen receptor may be altered in these prostate carcinoma cells. Several cDNA (AR) clones to the LNCaP/A-dep androgen receptor were isolated and the DNA sequence was determined. A point mutation in the steroid binding domain at amino acid 877 converts a threonine to an alanine in the LNCaP/A-dep AR. This mutation was confirmed by PCR techniques and sequencing the relevant region in LNCaP/A-dep DNA and normal human liver DNA. The role the Thr to Ala mutation plays in steroid-dependent transactivation is now being tested by co-transfection of wild-type AR and LNCaP/A-dep AR expression vectors with MMTV-CAT and rat SVS IV-CAT reporter genes.