二甲双胍通过下调c-Myc增强人乳腺癌MDA-MB-231细胞对他莫昔芬的敏感性

Metformin sensitizes human breast cancer MDA-MB-231 cells to tamo-xifen through down-regulation of c-Myc

目的:研究二甲双胍是否通过下调c-Myc增强人乳腺癌MDA-MB-231细胞对他莫昔芬的敏感性。方法:CCK-8法、平板集落形成实验、流式细胞术和Transwell实验检测二甲双胍和他莫替芬单独/联合作用对MDA-MB-231细胞活力、集落形成能力、肿瘤细胞凋亡率及迁移和侵袭能力的影响;Western blot和免疫组化实验检测细胞和肿瘤组织中c-Myc的表达水平;建立SCID小鼠MDA-MB-231细胞皮下移植瘤模型,以研究二甲双胍和他莫昔芬在体内对三阴性乳腺癌的影响。结果:与对照组和单独用药组相比,二甲双胍联合他莫昔芬协同抑制MDA-MB-231细胞的活力和迁移能力,对集落形成、凋亡诱导和侵袭能力表现为相加效应(P<0.01);二甲双胍和他莫昔芬单独或者联合下调c-Myc蛋白的水平(P<0.01)。进一步研究表明,二甲双胍和他莫昔芬可能通过下调c-Myc抑制SCID小鼠皮下移植瘤的生长(P<0.01)。结论:二甲双胍联合他莫昔芬通过下调c-Myc抑制三阴性乳腺癌MDA-MB-231细胞的增殖、迁移和侵袭以及SCID小鼠的肿瘤生长。二甲双胍联合他莫昔芬有望成为三阴性乳腺癌的一种有效的治疗手段。

AIM:To investigate whether metformin enhances the sensitivity of human breast cancer MDA-MB-231 cells to tamoxifen by down-regulating c-Myc.METHODS:The cell viability,colony formation,apoptosis,and migration and invasion abilities of MDA-MB-231 cells were detected by CCK-8 assay,colony formation experiment,flow cytometry and Transwell assay.The expression level of c-Myc was quantified by Western blot and immunohistochemical analysis.The antitumor effects of metformin and tamoxifen were investigated in vivo in a MDA-MB-231 triple-negative breast cancer xenograft model in the SCID mice.RESULTS:Metformin in combination with tamoxifen exerted synergistic effects on inhibition of the viability,colony formation,migration and invasion,and induced the apoptosis compared with the controls and either agent treatment alone in the MDA-MB-231 cells.The levels of c-Myc was down-regulated in vitro by treatment with metformin and/or tamoxifen(P<0.01).Moreover,metformin or in combination with tamoxifen also reduced the growth of MDA-MB-231 breast cancer tumors in the SCID mice by down-regulation of c-Myc in vivo.CONCLUSION:Metformin in combination with tamoxifen exerts synergistic effects on inhibition of the proliferation,migration,invasion and tumor growth of human triple-negative breast cancer MDA-MB-231 cells by down-regulating c-Myc expression,suggesting that metformin in combination with tamoxifen merits further evaluation as a target.