甘氨双唑钠下调X射线照射诱导鼻咽癌细胞hMSH2的表达

目的：通过甘氨双唑钠（CMNa）对X 射线照射诱导鼻咽癌CNE-1 细胞错配修复基因hMSH2 表达的影响,探讨CMNa放射增敏的分子机制.方法：应用逆转录酶PCR（RT-PCR）和免疫印迹方法,检测空白组（未照射）、对照组（未加入CMNa进行照射）和实验组（加入1 mmol/l CMNa,每次加入60 min后进行照射）细胞中hMSH2 基因mRNA 及蛋白表达.结果：对照组细胞照射后hMSH2 mRNA 和蛋白表达量逐渐增高,且均高于基础表达量（0.11±0.03,10.27±3.96,P〈0.05）.实验组细胞在照射终止后第1 周hMSH2 mRNA和蛋白表达量最高,以后成逐渐降低,且在照射终止后第2~4 周mRNA（0.19±0.07,0.14±0.05,0.06±0.02）和蛋白表达水平（ 12.81±5.24,11.37±4.63,8.76±4.29） 均显著低于对照组（P〈0.05）.结论：CMNa 可以下调X 射线照射诱导鼻咽癌细胞hMSH2 的表达水平,抑制放射损伤后肿瘤细胞DNA 修复,这可能是肿瘤放疗敏感性增高的原因之一.

CMNa down-regulates hMSH2 expression in nasopharyngeal cells after X-ray radiation

Objective：To explore the molecular mechanism of CMNa radiosensitization in a study on effects of CMNa on hMSH2 expression in nasopharyngeal carcinoma （NPC） CNE-1 cells. Methods： hMSH2 mRNA and protein expression was detected in CNE-1 cells of blank group （without X-ray radiation ） ,control group （with X-ray radiation but no CMNa） and experiment group （X-ray radiation for 60 min with addition of 1 mmol/LCMNa） by using RT-PCR and Western-blotting. Results： After X-ray radiation, both levels of hMSH2 mRNA and protein expression in the control group increased gradually from baseline （0.11 ± 0.03,10.27 ± 3.96） （ P 〈 0.05 ）. At one week after X-ray radiation,the levels of hMSH2 mRNA and protein expression in experiment group reached a peak level and then declined gradually. In weeks 2 to 4 post-radiation,the levels of hMSH2 mRNA （0.19 ±0.07,0.14 ± 0.05,0.06 ± 0.02） and protein （ 12.8 ± 5.24,11.37 ± 4.63,8.76 ± 4.29 ） expression were both lower than those in the control group （ P 〈 0.05 ）. Conclusion ： CMNa may down-regulate hMSH2 mRNA and protein expression induced by X-ray radiation by inhibition of carcinoma cells DNA repairing after radiation damage, and therefore may contribute to increased susceptibility to radiotherapy.