miR -21通过调控 PTEN 介导乳腺癌他莫昔芬耐药的作用机制

目的：研究 miR -21在乳腺癌他莫昔芬耐药中的作用，寻求逆转他莫昔芬耐药的靶点。方法：荧光实时定量 PCR（RT - QPCR）检测乳腺癌 MCF -7细胞与乳腺癌他莫昔芬耐药细胞株 MCF -7/ TAM 细胞中miR -21的表达；将 miR -21 mimics 转染到 MCF -7细胞内，将 miR -21 inhibitors 转染到 MCF -7/ TAM 细胞内，并应用 RT - QPCR 分别检测细胞内 miR -21的表达变化，给予细胞4-羟他莫昔芬（4- hydroxytamoxifen， OHT）处理后，利用 MTT 法检测细胞增殖的变化；转染 MCF -7/ TAM 细胞 miR -21 inhibitors 及 mimics，利用RT - QPCR 检测细胞中 PTEN 的表达变化。结果：miR -21在 MCF -7/ TAM 细胞表达高于 MCF -7细胞，转染 miR -21 mimics 的 MCF -7细胞 miR -21高表达，PTEN 表达降低，转染 miR -21 inhibitors 的 MCF -7/TAM 细胞 miR -21表达降低，PTEN 表达增高；过表达 miR -21的 MCF -7细胞给予 OHT 处理后，细胞的增殖抑制不明显，而沉默 miR -21的 MCF -7/ TAM 细胞给予 OHT 处理后，细胞增殖明显受到阻滞；转染耐药细胞 miR -21 inhibitors 后，PTEN 表达增高，转染 miR -21 mimics 后，PTEN 表达降低。结论：miR -21通过调控PTEN 的表达在乳腺癌 TAM 耐药中发挥重要作用。

The role of miR - 21 in regulations of tamoxifen resistant breast cancer via regulating the expression of PTEN

Objective:To study the role of miR - 21 in tamoxifen resistant breast cancer,expecting to find the tar-gets of tamoxifen resistance be sensitized. Methods:The expression of miR - 21 in MCF - 7 and MCF - 7 / TAM cells was detected by RT - QPCR. MiR - 21 mimics was transfected into MCF - 7 cells,the expression of miR - 21 in MCF- 7 was detected by RT - QPCR. MiR - 21 inhibitors were transfected into MCF - 7 cells,the expression of miR - 21 in MCF - 7 was detected by RT - QPCR. After treated by OHT,to detect the cells proliferation in each group by MTT. The expression of PTEN was detected in MCF - 7 / TAM group,miR - 21 mimics group and miR - 21 inhibitors group. Results:The expression of miR - 21 in MCF - 7 / TAM cells wad higher than MCF - 7 cells. The expression of miR -21 was increased in MCF - 7 cells transfected with miR - 21 mimics. The expression of miR - 21 was decreased in MCF - 7 / TAM cells transfected with miR - 21 inhibitors. The OHT had little effect on the growth of MCF - 7 cells transfected with miR - 21 mimics,and OHT could inhibit the growth of MCF - 7 / TAM cells transfected with miR - 21 inhibitors. PTEN expression was increased after transfected miR - 21 inhibitors. PTEN expression was decreased after transfected miR - 21 mimics. Conclusion:miR - 21 plays an important role in tamoxifen resistant breast cancer via regulating the expression of PTEN.