Hurd C, Khattree N, Dinda S, Alban P, Moudgil V K
Department of Biological Sciences and the Institute of Biochemistry and Biotechnology, Oakland University, Rochester, Michigan 48309-4401, U.S.A.
Oncogene. 1997 Aug 18;15(8):991-5. doi: 10.1038/sj.onc.1201233.
We have utilized the estrogen receptor (ER)-positive human breast carcinoma cell line, T47D, to determine the role of ER in regulating cell proliferation, the level of expression of p53 and the state of phosphorylation of retinoblastoma protein (pRB) by 17 beta-estradiol (E2) and antiestrogens. T47D cells cultured for 7 days proliferated rapidly expressing maximal levels of p53 in medium containing 5% fetal bovine (whole) serum. Exogenously added E2 had no effect on either of the above parameters. The antiestrogen, ICI 164,384 (ICI, 1 microM), decreased cell number and p53 level to nearly 20% of the control. Comparatively, a treatment of the cells with 100 nM 4OH-tamoxifen (OHT) decreased cell number to 40% of the control without a concomitant decrease in the p53 levels suggesting a differential ability of these antiestrogens to regulate p53 levels in cells cultured in whole serum. When cells were cultured in medium containing serum depleted of endogenous steroids (charcoal stripped serum), cell number and p53 levels declined. Treatment with exogenous E2 (1 nM) increased cell proliferation, p53 expression and phosphorylation of pRB. The antiestrogens ICI and OHT blocked these E2 effects, demonstrating a direct antagonism of ER by ICI and OHT. These results indicate an ER-mediated mechanism for coordinate expression of p53 and hyperphosphorylation of pRB during E2-induced proliferation of T47D cells.
我们利用雌激素受体（ER）阳性的人乳腺癌细胞系T47D，来确定ER在调节细胞增殖、p53表达水平以及17β-雌二醇（E2）和抗雌激素对视网膜母细胞瘤蛋白（pRB）磷酸化状态方面的作用。在含有5%胎牛（全）血清的培养基中培养7天的T47D细胞迅速增殖，p53表达达到最高水平。外源性添加的E2对上述任何参数均无影响。抗雌激素ICI 164,384（ICI，1 microM）可使细胞数量和p53水平降至对照的近20%。相比之下，用100 nM 4-羟基他莫昔芬（OHT）处理细胞可使细胞数量降至对照的40%，而p53水平并未随之降低，这表明这些抗雌激素在全血清培养的细胞中调节p53水平的能力存在差异。当细胞在含有去除内源性类固醇的血清（活性炭处理血清）的培养基中培养时，细胞数量和p53水平下降。用外源性E2（1 nM）处理可增加细胞增殖、p53表达以及pRB的磷酸化。抗雌激素ICI和OHT可阻断这些E2的作用，表明ICI和OHT对ER具有直接拮抗作用。这些结果表明，在E2诱导T47D细胞增殖过程中，存在一种ER介导的机制来协调p53的表达和pRB的过度磷酸化。
