title: The effects of natural ligands of hormone receptors and their antagonists on telomerase activity in the androgen sensitive prostatic cancer cell line LNCaP.
abstract: The effects of the 17beta-estradiol, dihydrotestosterone and hormone antagonists tamoxifen and bicalutamide on telomerase activity and expression of cell cycle related proteins in the androgen-sensitive prostatic cancer cell line LNCaP were studied. The cell line was grown in RPMI supplemented with 2.5% charcoal-stripped FBS for 72 hr. The IC(50) of tamoxifen and bicalutamide and the optimal stimulatory concentrations of 17beta-estradiol and dihydrotestosterone were determined by means of the cell-viability assay, the activity of telomerase was measured by the telomere repeat amplification protocol (TRAP) and the expression of proteins was analysed by the Western blot technique. 17beta-estradiol stimulated cell growth more effectively than dihydrotestosterone whereas hormone antagonists tamoxifen and bicalutamide caused a significant decrease in cell viability. The treatment of cells by a combination of low doses of 17 beta-estradiol and dihydrotestosterone stimulated cells stronger than treatment by a single hormone. Only 17beta-estradiol, in concentration of 10nM, increased strongly the expression of p21(Waf1/Cip1) and increased slightly telomerase activity in the LNCaP cells. 50 microM of bicalutamide down-regulated the levels of the androgen receptor, the proliferating cell nuclear antigen and telomerase activity, and up-regulated the expression of p27(Kip1). We hereby describe the first observation of the influence of bicalutamide on telomerase activity and a positive correlation between the effect of 17beta-estradiol and the induction of both the endogenous cyclin-dependent kinase inhibitor, p21(Waf1/Cip1), and telomerase activity in a prostatic cancer cell line LNCaP. These findings can shed a new light on the steroid-signaling pathway in prostate cancer cells.
authors.affiliation: Laboratory of Molecular Pathology, CMBM and Institute of Pathology, Faculty of Medicine, Palacký University, Olomouc, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Bouchal
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Kolár
authors.forename: Jana
authors.initials: J
authors.lastname: Mad'arová
authors.forename: Alice
authors.initials: A
authors.lastname: Hlobilková
authors.forename: Erwin
authors.initials: E
authors.lastname: von Angerer
mesh_terms: D000728:Androgens / Q000378:metabolism; D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology; D013196:Dihydrotestosterone / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology*; D006801:Humans; D015151:Immunoblotting; D008024:Ligands; D008297:Male; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000473:pathology; D018026:Receptors, Pancreatic Hormone / Q000037:antagonists & inhibitors*; D013629:Tamoxifen / Q000494:pharmacology; D019098:Telomerase / Q000187:drug effects / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D000728:Androgens; D018931:Antineoplastic Agents, Hormonal; D008024:Ligands; D018026:Receptors, Pancreatic Hormone; D013196:Dihydrotestosterone; D013629:Tamoxifen; D004958:Estradiol; D019098:Telomerase