雌激素对乳腺癌细胞中PDZK1蛋白表达量的影响

目的观察雌激素17β-雌二醇(17β-estradiol,E2)及其抑制剂对雌激素受体(estrogen receptor,ER)阳性的乳腺癌细胞株ER-MDA-MB-231、MCF-7中PDZK1(PDZ domain containing1)蛋白表达量的影响。方法应用Western blotting法观察E2及ICI182,780在不同时间、不同浓度作用下2种细胞内PDZK1蛋白表达量的变化。结果浓度为10-8mol/L的E2作用72h可以使MCF-7、ER-MDA-MB-2312株细胞内PDZK1蛋白表达量显著升高;而抑制剂ICI182,780则相反,以10-6mol/L的浓度作用36h即可明显抑制ER-MDA-MB-231细胞中PDZK1蛋白的表达,且以上变化表现出剂量、时间依赖关系。结论PDZK1是雌激素应答蛋白,它在ER阳性的乳腺癌细胞中的表达受雌激素信号转导通路的调节。雌激素及ICI182,780可能通过调节其蛋白表达量来影响肿瘤细胞的生长和耐药性。

Effect of Estrogen on PDZK1 Protein in Breast Cancer Cells

Objective Exposure to estrogen is an important independent determinant factor of breast cancer. Many estrogen responsive proteins play an important role in breast cancer occurrence and development. Our study is to investigate the effects of 17β-estradiol(E2) and ICI182,780 (the estrogen receptor antagonist, Faslodex), at different concentrations and different times, on the expression level of the PDZK1(PDZ domain containing 1) protein in ER-MDA-MB-231, MCF-7 cell lines which were ER(+) and MDA-MB-231 cell lines which were ER(-). Methods MDA-MB-231, ER-MDA-MB-231 and MCF-7 cell lines were all incubated for 48 hours in RPMI 1640 medium which was free of phenol red supplemented with 10% charcoal-stripped fetal bovine serum, which aimed to remove the estrogen effects of fetal bovine serum and estrogen-like effects of phenol red in the medium respectively. Western Blot was used to analyse the expression levels of PDZK1 protein in MCF-7 and ER-MDA-MB-231, two ER(+) breast cancer cell lines, at different time points with different doses of 17β-estradiol and ICI182,780. The ER(-) cell line, MDA-MB-231, was used as control. Results Physiological 17β-estradiol could obviously up-regulate PDZK1 protein expression level in ER(+) breast cancer cell lines. The Western Blot analysis showed that after the treatment of 17β-estradiol at the concentration of 10^-8 mol/L for 72 hours, the PDZK1 protein expression level was significantly up-regulated in the two strains of MCF-7 and ER-MDA-MB-231 breast cancer cell lines, which was time and dose dependent. Compared with 17β-estradiol, the effects of ICI182,780 was the exactly opposite: after the treatment with ICI182,780 at the concentration of 10^-6 mol/L for 36 hours, the PDZK1 protein expression level was suppressed in ER-MDA-MB-231 significantly. The ICI182,780 effects were obvious when the concentration was 10^-5 mol/L. In MDA-MB-231 breast cancer cell line which was ER(-), the expression level of PDZK1 did not change as much as the ER(+) breast cancer cell lines, when treated with the same concentration of 17β-estradiol and ICI182,780 at the same time. Conclusion Our study demonstrates that the PDZK1 protein is estrogen responsive. The expression level of PDZK1 protein in ER(+) breast cancer cell lines was mediated through ER signaling transduction pathway. 17β-estradiol and ICI182,780 may affect the cell growth and the drug resistance by regulating the expression level of PDZK1. This finding may provide a new theoretical basis for ER(+) breast cancer endocrinotherapy.