目的

探讨雌激素受体(ER)亚型 (ERβ)及其剪切变异体(ERβcx)的表达与乳腺癌他莫昔芬耐药的关系。

方法

(1)对乳腺癌他莫西芬敏感MCF-7 细胞和他莫西芬耐药MCF-7 细胞进行培养,利用去甲基化物5-氮杂胞苷(5-Aza-2-deoxycytidine,5-AZA-CdR)去甲基化的作用,对MCF-7 细胞进行药物处理获得MCF-7^5-AZA-CdR 细胞,采用Western blot 方法检测3 组细胞中ERβ 和ERβcx 蛋白的表达。 (2)取对数生长期生长良好的乳腺癌MCF-7 细胞株,按2.5×10³ 细胞/孔接种于96 孔细胞培养板板中,实验组分为他莫细芬处理的MCF-7 细胞(MCF-7+TAM 组)和MCF-7^5-AZA-CdR 细胞(MCF-7^5-AZA-CdR 细胞+TAM 组),对照组为MCF-7 细胞,采用MTT 比色法,观察3 组细胞的增殖情况。 统计学分析采用单因素方差分析和重复测量方差分析。

结果

(1) ERβ 蛋白在他莫西芬敏感MCF-7 细胞中的表达高于他莫西芬耐药的MCF-7 细胞,两组细胞间差异有显著的统计学意义(P=0.000);ERβcx 蛋白表达在两组之间差异无统计学意义(P=0.366)。 MCF-7^5-AZA-CdR 细胞ERβ 和ERβcx 蛋白表达均高于他莫西芬敏感MCF-7 细胞和他莫西芬敏耐药MCF-7 细胞(P 均=0.000)。 (2)与对照组MCF-7 细胞相比,他莫西芬明显降低了MCF-7+TAM 组和MCF-7^5-AZA-CdR 细胞+TAM 组的细胞增值速度并抑制细胞生长;且他莫西芬抑制细胞增殖作用MCF-7^5-AZA-CdR 细胞+TAM 组强于MCF-7+TAM组(P=0. 000)。

结论

ERβ 蛋白在他莫西芬敏感MCF-7 细胞中的表达高。 MCF-7^5-AZA-CdR 细胞中ERβ 和ERβcx 蛋白的表达均高。 他莫西芬抑制细胞增殖作用在他莫西芬处理的MCF-7^5-AZA-CdR 细胞中强。

Objective

To study the relationship of ERβ (estrogen receptor β)protein and its isoform (ERβcx ) with tamoxifen resistance in human breast cancer.

Methods

(1) Tamoxifen-sensitive MCF-7 cells and tamoxifen-resistance MCF-7 cells were cultured. A demethylation drug named 5-Aza-2-deoxycytidine (5-AZA- CdR) was used to treat human breast cancer MCF-7 cells to obtain MCF-7^5-AZA-CdR cells. Western blot method was used to detect the expressions of ERβ and ERβcx proteins in the three groups. (2) Fully-developed MCF-7 cells in log phase growth were seeded at 2. 5×10³ cells/well in 96-well tissue culture plates. The experimental groups included tamoxifen-treated MCF-7 cells (MCF-7 cells+ TAM group) and tamoxifen-treated MCF-7^5-AZA-CdR cells (MCF-75-AZA-CdR cells +TAM group), and the control group was MCF-7 cells without any treatment. MTT assay was used to observe the cell proliferation of the three groups. Statistical analysis was done using one-way analysis of variance and repeated measures.

Results

(1) The expression of ERβ protein in the tamoxifen-sensitive MCF-7 cells was higher than in the tamoxifen-resistant MCF-7 cells (P=0.000), but there was no statistical difference in ERβcx protein expression between the two groups (P=0.366). The expressions of both ERβ and ERβcx proteins in the MCF-7^5-AZA-CdR cells were the highest among the three groups, (both P=0.000). (2) Compared with the control group of MCF-7 cells, tamoxifen significantly reduced the cell proliferation in the MCF-7 cells+TAM group and the MCF-7^5-AZA-CdR cells +TAM group, and the effect of tamoxifen inhibiting cell growth in the MCF-7^5-AZA-CdR cells+TAM group was greater than in the MCF-7 cells+TAM group (P=0.000).

Conclusion

The ERβ expression in the tamoxifen-sensitive MCF-7 cells is high. The expressions of both ERβ and ERβcx proteins in the MCF-7^5-AZA-CdR cells are high. The effect of tamoxifen inhibiting cell growth is high in the tamoxifen treated MCF-7^5-AZA-Cdr cells.