Studies on the human prostatic cancer cell line LNCaP

Area of Science:

• * Molecular endocrinology
• * Cancer cell biology
• * Pharmacology

Background:

• * LNCaP cells, a human prostate cancer line, respond aberrantly to steroid hormones.
• * Estrogens and progestagens stimulate growth despite lacking specific receptors.
• * Most antiandrogens also promote LNCaP cell growth, indicating a dysfunctional androgen receptor (AR).

Purpose of the Study:

• * To investigate the effects of androgens, antiandrogens, and other steroid hormones on LNCaP cell growth.
• * To elucidate the mechanism behind the aberrant response to steroid hormones in LNCaP cells.
• * To identify antiandrogens capable of inhibiting the mutant AR.

Main Methods:

• * Cell culture of LNCaP-FGC cells with various steroid hormones.
• * Analysis of androgen receptor (AR) mutation via amino acid substitution.
• * Immunoprecipitation and Western blotting to study AR-associated heat-shock proteins.
• * Assessment of antiandrogen efficacy in blocking AR function and cell growth.

Main Results:

• * A mutation (T868A) in the AR steroid-binding domain causes aberrant growth stimulation by estrogens, progestagens, and most antiandrogens.
• * The antiandrogen ICI 176,334 effectively blocked transcription and growth mediated by the mutant AR.
• * Heat-shock proteins (hsp90, hsp70, hsp56) co-precipitated with the AR.
• * Androgens and hydroxyflutamide prevented AR-heat shock protein complex dissociation.
• * ICI 176,334 inhibited AR nuclear binding, while hydroxyflutamide only affected wild-type AR binding.

Conclusions:

• * A specific AR mutation in LNCaP cells leads to paradoxical growth stimulation by various steroid hormones.
• * Most antiandrogens are ineffective against this mutant AR, except for ICI 176,334.
• * ICI 176,334 likely employs a distinct mechanism to inhibit the mutant AR compared to hydroxyflutamide.