Biological activity and binding of estradiol to SK-Mel 23 human melanoma cells

摘要: Patients expressing estradiol receptors in melanoma cells have been reported to a better prognosis. We therefore decided investigate the vitro effects of s-estradiol and tamoxifen on growth tyrosinase activity SK-Mel 23 human cells. Twenty-four-hour treatment with 0.4 nM inhibited cell proliferation 30% (0.70 ± 0.03 x 105 cells) increased 50% (7130.5 376.5 cpm/105 cells), as compared untreated (1.0 0.05 4769 25.5 cells, respectively). Both responses were completely (100%) blocked by 1 µM tamoxifen. Higher concentrations (up 1.6 nM) or longer treatments 72 h) did not result larger effect hormone activity. Competition binding assays demonstrated presence sites [2,4,6,7-3H]-s-estradiol, that tritiated analogue was displaced unlabeled (1 100 µM, Kd = 0.14 maximal displacement 93%) 10 (displacement 60%). also phosphorylated state two proteins 16 46 kDa, after 4-h treatment, determined Western blot. The absorbance each band 1.9- 4-fold controls, respectively, Image-Pro Plus software. Shorter incubation periods enhance phosporylation; 6-h hormone, returned control phosphorylation levels. inhibition promoted may explain prognosis melanoma-bearing women men, open new perspectives for drug therapy.