DNA甲基化介导乳腺癌细胞内Mfn2基因沉默

Silencing of Mitofusin2 by DNA Methylation in Human Breast Cancer

目的探讨人乳腺癌细胞中线粒体融合蛋白（mitofusin2，Mfn2）基因沉默的表观遗传学机制。方法实时荧光定量PCR法检测人乳腺癌细胞系MCF-7及乳腺癌组织中Mfn2的mRNA水平；细胞免疫化学染色法和Western印迹法检测其蛋白水平；甲基化特异性PCR法检测Mfn2启动子区甲基化状态；MTF法及流式细胞仪检测细胞增殖及周期。结果与对照组相比，MCF-7细胞及癌旁组织中Mfa2均呈低水平表达（P〈0．05），而Mfn2启动子区均呈高甲基化状态（P〈0．05）。5-氮-2’-脱氧胞苷（5-aza-2‘deoxycytidine，5-aza．CdR）处理可降低Mfn2启动子区甲基化水平，其表达水平相应增高，细胞生长受到抑制。结论Mfn2启动子区甲基化是其在乳腺癌细胞内沉默的重要的表观遗传学调控机制。

Objective To clarify the epigenetic mechanisms of Mitofusin2 （Mfn2） silencing in human breast cancer. Methods The mRNA levels of Mfn2 were detected by real-time quantitative polymerase chain reaction （qPCR） in human breast cancer cells and breast cancer tissues and its protein levels were measured by cell immunochemistry and Western blotting, respectively. The meth- ylation status of Mfn2 promoter was analyzed by methylation-specific PCR. The proliferation and cell cycle of MCF-7 cells were evaluated by MTT and flow cytometry. Results Mfn2 was down-ex- pressed in MCF-7 cells and breast cancer tissues when compared with that in control group （P 〈 0. 05 ） . The promoter of Mfn2 was found hypermethylated in human breast cancer. Demethylation of Mfrt2 promoter by 5-aza-2＇-deoxycytidine （5-aza-CdR） upregulated the Mfn2 levels and reduced the proliferation of MCF-7 cells. Conclusion The methylation status of Mfn2 promoter is an important epigenetic mechanism in the tumorigenesis of breast cancer.