低剂量照射对细胞周期和修复基因表达的影响

目的观察低剂量照射对A549(肺癌细胞)和2BS细胞(人胚胎肺成纤维细胞)细胞周期及修复基因表达的影响.探讨肿瘤细胞与正常细胞在诱导修复基因表达方面的差异,并结合细胞周期变化,进一步阐明适应性反应形成机制.方法(1)应用流式细胞技术,对不同剂量照射后A549和2BS细胞周期进行分析;(2)应用Northern-blot检测不同照射剂量DNA修复基因hR24L、bRAD6和bRAD52转录水平的变化.结果(1)2BS细胞经75mGy X线照射组,及低剂量加高剂量照射组于照后30分钟即出现明显的G2期阻滞,且细胞周期于24小时内恢复.A549细胞在75mGy X线照射后,细胞周期未发生变化;(2)2BS细胞在75mGy X照射下,hR24L、hRAD6表达增强,bRAD52无变化.A549细胞低剂量照射修复基因表达未见显著变化.结论低剂量照射后2BS细胞与A549细胞周期改变存在差异,且细胞周期的调控与DNA修复基因的表达有着密切的关系.

Effet of low does irradiation on expression of DNA repair genes and cell cycle of A549 and 2BS cells

Objective To investigate the effect of low does irradiation on expression of DNA repair genes and cell cycle of A549 and 2BS cells. Moreover, to explore the molecular biological mechanism of adaptive response. Methods (1)Northern - blot technology was employed to determine hR24L,hRAD6,hRAD52 mRNA levels. (2)Flow cytometry (FCM) was used to analyze the cell cycle after irradiation different doses. Results (1)G2 phase arrest of 2BS cells after 75mGy X - ray and 75mGy X-ray plus 4Gy 60Cor-ray irradiation appeared in 30 minutes, and cell cycle recovered in 24 hours. (2)hR24L,hRAD6,hRAD52 showed no changes at mRNA level in A549 cell by low dose irradiation. The hR24L,hRAD6 mRNA levels became elevated in 2BS cells exposed to low dose irradiation, hR24L,hRAD6,hRAD52 mRNA level increased in 2BS cell by 75mGy X - ray plus 4Gy60 Cor-ray irradiation, the degree of enhancement in which was higher than that of single 4Gy 60Cor- ray irradiation. Conclusion hR24L,hRAD6 seems to pky important roles in radiationinduced G2 arrest.