Anti-androgens and the mutated androgen receptor of LNCaP cells: differential effects on binding affinity, heat-shock protein interaction, and transcription activation.
Previous studies from this laboratory have described that LNCaP prostate tumor cells contain an androgen receptor (AR) with a point mutation in the steroid-binding domain (codon 868, Thr to Ala). This defect leads to a change in specificity of the AR. Estrogens, progestagens, and some anti-androgens (e.g., cyproterone acetate, hydroxyflutamide, nilutamide) stimulate LNCaP cell growth rate through the AR. The present studies indicate that not all anti-androgens showed agonistic effects with the mutated receptor. The growth rate of LNCaP cells did not increase with the anti-androgen ICI 176334, nor could this compound increase transcription activation of the reporter gene construct via the mutant receptor in a cotransfection system [HeLa cell cotransfection system with an androgen-regulated reporter gene construct (pG29G-tk-CAT) and the mutant receptor as trans-vector]. Interaction of the AR of LNCaP cells with heat-shock proteins was studied by isolation of the receptor with a specific monoclonal antibody and characterization of associated proteins. Hsp90, hsp70, and hsp56 were found to coprecipitate with the AR. Incubation of the cells at 37 degrees C with androgen (R1881, 10 nM) or the anti-androgen hydroxyflutamide, prior to receptor isolation, resulted in dissociation of the AR-heat-shock protein complex. This dissociation is paralleled by the transformation to a tight nuclear-binding form of the AR. In contrast, ICI 176334 could not induce a release of heat-shock proteins and did not increase nuclear binding, but inhibited the transformation process induced by R1881.(ABSTRACT TRUNCATED AT 250 WORDS)
Veldscholte
J
J
Department of Endocrinology and Reproduction, Erasmus University, Rotterdam, The Netherlands.
Berrevoets
C A
CA
Brinkmann
A O
AO
Grootegoed
J A
JA
Mulder
E
E
D000726:Androgen Antagonists / Q000494:pharmacology*; D002455:Cell Division; D002467:Cell Nucleus / Q000378:metabolism; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006367:HeLa Cells; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008297:Male; D009154:Mutation; D011471:Prostatic Neoplasms / Q000737:chemistry / Q000235:genetics*; D011485:Protein Binding; D011944:Receptors, Androgen / Q000187:drug effects / Q000235:genetics*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D000726:Androgen Antagonists; D006360:Heat-Shock Proteins; D011944:Receptors, Androgen; D015500:Chloramphenicol O-Acetyltransferase