氯化镉对DNA修复的影响及机制的体外研究

Study on Effects of CdCl_2 on DNA Repair in vitro and Its Mechanism

目的通过体外实验,了解氯化镉(CdCl2)对过氧化氢(H2O2)引起的V79细胞DNA损伤后修复过程的影响及其相关机制。方法采用MTT法了解CdCl2对于V79细胞的毒性;以单细胞凝胶电泳实验分析软件中的几个评价指标,同时观察无细胞毒性浓度的CdCl2对H2O2所引起的V79细胞DNA损伤后修复所产生的影响;以生理浓度的氯化锌(ZnCl2)作为拮抗剂,与CdCl2同时作用后,观察对DNA修复影响的变化。结果MTT实验中,CdCl2对V79细胞的毒性随染毒浓度增加而增强,呈线性关系;在碱性单细胞凝胶电泳实验中,无细胞毒性浓度的CdCl2未明显增强H2O2V79细胞DNA的损伤,却明显地抑制了由H2O2所致的V79细胞DNA损伤后的修复过程,并以0.1μmol/L CdCl2浓度最为明显;生理浓度的锌可有效拮抗CdCl2的DNA修复抑制作用。结论在本实验条件下,无细胞毒性浓度的CdCl2对H2O2的DNA损伤效应无协同作用,却明显抑制DNA损伤后的修复过程;锌在一定程度上可以拮抗CdCl2的DNA修复抑制效应。

Objective To investigate the effects of CdCl2 on DNA repair in Chinese hamster lung fibroblast cells （V79） induced by hydrogen peroxide （H2O2） and its mechanism. Methods MTT assay was used to detect the cytotoxicity of CdCI2 on V79 cell line and the effects in the DNA repair on the damage induced by H2O2 by non-cytotoxic concentration of CdCl2 adopting the indexes of SCGE assay. Taking ZnCl2 as the antagonist, when reacts simultaneously with CdCl2, the effect on DNA repair process was also investigated, Results The CdCl2 dosage ranging from 5-40μmol/L could inhibit the cellular proliferation effectively after incorporated for 24 h; the effect was in a linear manner. CdCl2 of non-cytotoxic concentrations could significantly inhibit DNA repair process, among which 0. 1 μmol/L of CdCl2 being the most effective. ZnCl2 of 10 μmol/L could protect cells from the inhibition of DNA repair caused by CdCl2. Conclusions There are no coordinated effects on DNA damage between CdCl2 and H2O2, however, CdCl2 of non-cytotoxic concentrations could markedly inhibit the normal course of DNA repair, which ZnCl2 could withstand. Replacement of Zn^2＋ ion by Cd^2＋ may partly account for the mechanism of genotoxicity of cadmium.