miR-1246增强宫颈癌细胞辐射敏感性的分子机制研究

目的:探讨微小RNA-1246(miR-1246)过表达增强宫颈癌细胞放疗敏感性的分子机制。方法:运用脂质体2000将miR-1246模拟物(miR-1246 mimic)转染4种宫颈癌细胞系He La、Ca Ski、C33A和Si Ha,以阴性对照模拟物(NC-mimic)为阴性对照。Real-time PCR检测宫颈癌组织、正常组织、子宫内膜上皮细胞系ESC和4株宫颈癌细胞中miR-1246的表达水平;转染的细胞经电离辐射照射后运用MTT法和Transwell法分别测定细胞活力和细胞迁移能力;运用免疫荧光法检测γH2AX表达水平;Western blot检测细胞中γH2AX、ATM、p-ATM和p-p53的蛋白水平。结果:miR-1246在正常组织和ESC细胞中高表达,而在4株宫颈癌细胞和宫颈癌组织中低表达;转染miR-1246 mimic后miR-1246表达水平显著高于NC-mimic组细胞(P 0. 05)。相同条件下,辐照后miR-1246过表达组宫颈癌细胞活力显著低于NC-mimic组,细胞迁移率明显降低(P 0. 05)。免疫荧光结果显示,miR-1246过表达显著增强电离辐射诱导的γH2AX激活(P 0. 05);Western blot结果显示,与NC-mimic组比较,miR-1246过表达显著促进电离辐射诱导γH2AX蛋白的表达,减低p-ATM和p-p53的蛋白水平(P 0. 05)。结论:miR-1246在正常组织和子宫内膜上皮细胞中高表达,而在宫颈癌组织和宫颈癌细胞系中低表达;miR-1246过表达抑制宫颈癌细胞活力和迁移能力,并可能通过阻断ATM通路、抑制DNA损伤修复而增强宫颈癌细胞的辐射敏感性。

Molecular mechanism of miR-1246 enhancing radiosensitivity of cervical cancer cells

AIM: To investigate the molecular mechanism of microRNA-1246(miR-1246) enhancing radiosensitivity of cervical cancer cells. METHODS: Cervical cancer lines HeLa, CaSki, C33A and SiHa were transfected with miR-1246 mimic and negative control mimic (NC-mimic) using Lipofectamine 2000 kit, and the expression level of miR-1246 in cervical cancer tissue, normal tissue, cervical cancer cell lines and endometrial epithelium cell line ESC was detected by real-time PCR. The transfected cells were exposed to X-ray radiation. The cell viability and migration rate were measured respectively by MTT assay and Transwell method. The protein levels of γH2AX, ATM, p-ATM and p-p53 were monitored by immunofluorescence and Western blot. RESUITS: Higher miR-1246 level was found in normal tissue and ESC cells, while lower miR-1246 level was found in HeLa, SiHa, C33A and Caski cells and cervical cancer tissues. The expression level of miR-1246 in the cells transfected with miR-1246 mimic was significantly higher than that in the cells transfected with NC-mimic (P<0.05). The cell viability and migration rate of the cervical cancer cells with miR-1246 over-expression were notably lower than those of the cells transfected with NC-mimic (P<0.05) under the same conditions. The results of immunofluorescence indicated that the protein expression level of γH2AX significantly increased in the cervical cancer cells with miR-1246 over-expression exposed to radiation compared with the negative control (P<0.05). The protein expression level of γH2AX was significantly increased in the cervical cancer cells with miR-1246 over-expression, while the protein levels of p-ATM and p-p53 were significantly decreased as compared with the negative control group (P<0.05). CONCLUSION: miR-1246 is highly expressed in normal tissue and normal endometrial epithelial cells, while is low expressed in the cervical cancer tissues or cells. miR-1246 over-expression inhibits growth and migration, and significantly enhances radiosensitivity of cervical cancer cells. The molecular mechanism is possibly related to inhibiting ATM pathway and DNA damage repair.