ATP1B1协同阿霉素抑制乳腺癌细胞MCF-7生长及逆转耐药的作用

Synergic effect of Na+-K+ ATPaseB1 and adriamycin on inhibition of cell proliferation and reversal of drug resistance in breast cancer MCF-7 cells

背景与目的:Na+-K+ATP酶(Na+-K+泵)是细胞能量转换的重要系统,可能与肿瘤转移有关,其B1亚基基因ATP1B1在高分化的肿瘤细胞中表达高,低分化细胞中表达低。本实验研究ATP1B1协同阿霉素(ADM)在人乳腺癌细胞株MCF-7和其耐药株MCF-7/ADM中的作用以及其逆转耐药效应的影响。方法:将重组质粒PEGFP-ATP1B1转染到MCF-7和MCF-7/ADM细胞,MTT法检测质粒及其B1亚基因沉默后ADM抑瘤效应,荧光显微镜和流式细胞术分析细胞内药物荧光强度,定磷法检测ATP酶活性,RT-PCR和real-time PCR检测MDR1 mRNA的表达,Western blot法检测P-gp蛋白的表达。结果:转染PEGFP-ATP1B1的MCF-7和MCF-7/ADM细胞对ADM的敏感性相对阴性对照ADM-C3组(pEGFP-C3空载体转染)和空白对照ADM-RPMI-1640组均明显增加,且ADM各浓度梯度ADM-ATP1B1组与ADM-RPMI-1640组比较差异有统计学意义(P<0.05);而B1亚基沉默后阴性对照组ADM-shNC,相对实验组ADM-shATP1B1和空白对照ADM-RPMI-1640组细胞对ADM的敏感性明显偏高。荧光显微镜下观察ADM-ATP1B1组MCF-7和MCF-7/ADM细胞ADM红色荧光均高于对照组。流式细胞术显示,ADM-ATP1B1组MCF-7细胞中ADM平均荧光强度较对照组高(P<0.05),ADM-ATP1B1组MCF-7/ADM细胞中ADM平均荧光强度高于对照组(P<0.05)。MCF-7和MCF-7/ADM细胞的ADM-ATP1B1组ATP酶活性均高于ADM-RPMI-1640组(P<0.05),而ADM-C3组与ADM-RPMI-1640组相比差异无统计学意义(P>0.05)。RT-PCR和real-time PCR检测结果显示,MCF-7/ADM细胞ADM-ATP1B1组MDR1 mRNA相对表达水平与两对照组相比差异均无统计学意义(P>0.05)。Western blot显示P-gp蛋白的表达水平差异无统计学意义(P>0.05)。结论:ATP1B1对ADM抑制乳腺癌细胞生长具有协同作用,并可逆转耐药细胞MCF-7/ADM对ADM的耐药效应,其机理与MDR1基因无明显的相关性,可能是通过与Na+-K+ATP酶相关的一种新途径而发挥作用的。

Background and Objective. Na^＋K^＋ATPase （Na^＋-K^＋ pump） is an important cell energy conversion system which is probably associated with tumor metastasis. Expression of its B1 subunit gene-ATP1B1 is high in well differentiated and low in poorly differentiated tumor cells. This study was to investigate the synergic effect of Na^＋-K^＋ ATPaseB1 and adriamycin （ADM） on inhibition of cell proliferation and reversal of drug resistance in MCF-7 and MCF-7/ADM cells. Methods： Growth of MCF-7 and MCF-7/ADM cells transfected with PEGFP-ATPIB1 and shATPIB1 were measured by MTT. Intracellular fluorescence intensity of ADM was analyzed by inverted fluorescence microscopy and flow cytometry. ATP enzyme activity was measured by ultramicro-ATP enzyme, and mRNA expression of multi-drug resistance gene MDR1 was detected by RT-PCR and real-time PCR. The expression of P-glycoprotein （P-gp） was analyzed by western blot. Results：The sensitivity of MCF-7 and MCF-7/ADM cells transfected with pEGFP- ATP1B1 to ADM was higher in comparing to the negative control ADM-C3 （transfected with vector pEGFP-C3） and the control ADM-RPMI-1640 （cultured with RPMI-1640）, and the differences between ADM-ATP1B1 and ADM-RPMI-1640 groups were statistically significant at different concentrations of adriamycin （P〈0.05）. After the B1 subunit was silenced, the sensitivity of cells to ADM in the ADM-shNC group was higher than that in the shATP and ADM-RPMI-1640 groups. The mean fluorescence intensity of ADM in the ADM-ATP1B1 group was higher than that in the ADM-C3 and ADM-RPMI-1640 groups （P〈0.05）. ATP enzyme activity was significantly higher in ADM-ATP1B1 group comparing to the ADM-RPMI-1640 group （P〈0.05）. mRNA expression of MDR1 gene and protein expression of P-gp were not significantly different among the ADM-ATP1B1 group and two control groups （P〉0.05）. Conclusion： Na^＋-K^＋ ATPase B1 can synergize with ADM and reverse drug resistance to ADM in the MCF-7/ADM cell line. This may be related to ATP enzyme activity, but not to influencing the expression of MDR1 gene.