MicroRNA let - 7f 对胃癌细胞株 SGC7901 / ADR 耐药性的影响

目的：通过检测胃癌细胞株SGC7901及其阿霉素耐药细胞株SGC7901/ADR中microRNA let-7f的表达差异,探讨let-7f表达与胃癌细胞对ADR耐药的关系.方法：通过实时荧光定量PCR比较SGC7901/ADR与SGC7901两种细胞中 let-7f表达水平的差异;MTT法检测SGC7901,SGC7901/ADR及转染let-7f mimic后SGC7901/ADR的药物敏感性;流式细胞仪检测细胞凋亡;Western Blot检测凋亡相关分子Bcl-2和Caspase-3蛋白表达情况.结果：qRT-PCR结果显示,let-7f在SGC7901/ADR细胞中的表达较在SGC7901中的表达显著降低（ P＜0.05）.MTT法结果显示SGC7901与SGC7901/ADR两种细胞阿霉素的半数抑制浓度（IC50）分别为（0.95 ±0.08）g/L和（5.40 ±0.28）g/L.SGC7901/ADR细胞转染let-7f mimic后,let-7f表达显著上调,并且对阿霉素的IC50明显降低（ P＜0.05）.凋亡检测结果显示,转染let-7f mimic后,SGC7901/ADR细胞凋亡率明显增加（ P＜0.05）.Western Blot结果表明相较于转染let-7f negative control（NC）组,转染let-7f mimic组cleaved-Caspase-3表达显著降低（P＜0.05）,而两组中的Bcl-2表达水平无差异.结论：let-7f在胃癌阿霉素耐药细胞株SGC7901/ADR中的表达显著降低,逆转let-7f表达可增加其对阿霉素敏感性,并诱导其凋亡.

The roles of microRNA let-7f on drug resistance in gastric cancer cell line SGC7901/ADR

Objective：To investigate the differential expression levels of mieroRNA let - 7f between SGC7901 and SGC7901/ADR,and explore the roles of let -7f on drug resistance in gastric cancer. Methods： Quantitative real - time PCR （qRT - PCR） was performed to detect the expression levels of let -7f in SGC7901/ADR and its parental cells SGC7901. Drug sensitivity to ADR in resistant SGC7901/ADR,parental SGC7901 cells and the SGC7901/ADR cells transfected with let -7f mimic by MTT assay. Cell apoptosis was analyzed by flow cytometry. The protein expres- sion of Bcl - 2 and Caspase - 3 were assayed by Western blot. Results：qRT - PCR analysis demonstrated that the ex- pression level of let -7f in resistant SGC7901/ADR was significantly lower than that in SGC7901 cell line（P 〈 0.05）. The half inhibition concentration（IC50） of ADR to SGC7901 and SGC7901/ADR cells were （0.95 ± 0.08） g/L and （5.40 ±0.28）g/L respectively by MTT assay. The let -7f expression was significantly upregulated and the IC50 was increased in the SGC7901/ADR transfected with let -7f mimic. The flow cytometry analysis showed that the rate of apoptosis in the SGC7901/ADR transfected with the let -7f mimic was significantly inereased（P 〈 0.05 ）. Furthermore, the Western blot indicated that the protein expression of cleaved - Caspase -3 were downregulat- ed but the expression of Bel - 2 was unchanged in let - 7f mimic transfected group,compared with those in miR - NC group. Conclusion：The expression level of let -7f in resistant SGC7901/ADR was significantly lower than that in SGC7901 cell line,reversing the expression of let -7f could increase drug sensitivity of gastric cancer cells to ADR and induce apoptosis.