镍和镉对人外周血淋巴细胞的DNA损伤作用

目的了解不同类型ＤＮＡ损伤在镍、镉遗传毒理中的不同意义。方法分别用ＮｉＣｌ２和ＣｄＣｌ２对人外周血淋巴细胞进行体外染毒,再用单细胞凝胶电泳法,测定其ＤＮＡ单链、双链断裂和ＤＮＡ蛋白质交联水平,同时用［３Ｈ］ＮＡＤ参入法测定了这些细胞的聚（腺苷二磷酸核糖）聚合酶（ＰＡＲＰ）活性。结果尽管在两种金属处理过的细胞中ＤＮＡ单链、双链断裂和ＤＮＡ蛋白质交联水平与对照相比均有明显增高,但只有０．１０～１０．００μｍｏｌ／Ｌ的ＮｉＣｌ２和０．１６～２０．００μｍｏｌ／Ｌ的ＣｄＣｌ２诱导的ＤＮＡ双链断裂呈剂量反应关系。两种金属在低浓度时（ＮｉＣｌ２０．１０～０．４０μｍｏｌ／Ｌ,ＣｄＣｌ２０．１６μｍｏｌ／Ｌ）还能通过诱导ＤＮＡ断裂而激活ＰＡＲＰ,高浓度时（ＮｉＣｌ２２．００～１０．００μｍｏｌ／Ｌ,ＣｄＣｌ２０．８０～２０．００μｍｏｌ／Ｌ）反而不激活该酶。结论ＤＮＡ双链断裂的形成和ＰＡＲＰ激活的受阻可能在镍和镉的致癌和致突变机制中起着重要的作用。

DNA damage in human peripheral blood lymphocyte caused by nickel and cadmium

OBJECTIVE: To understand the different implication of various forms of DNA damage in genotoxicity of nickel and cadmium. METHODS: Human peripheral lymphocyte was exposed to nickel chloride and cadmium chloride in vitro. Levels of DNA single-and double-strand breaks and DNA-protein crosslinks in human peripheral lymphocyte were determined with single cell gel electrophoresis (SCGE). Activity of poly (ADP-ribose) polymerase (PARP) was determined by (3)H]-NAD incorporating method. RESULTS: Levels of DNA single-and double-strand breaks and DNA-protein crosslinks in human peripheral lymphocyte treated with nickel and cadmium were significantly higher than those untreated, but dose-response relationship only showed in those treated with 0.10 - 10.00 micromol/L of nickel chloride and 0.16 - 20.00 micromol/L of cadmium. Low levels of the two kinds of metal (0.10 - 0.40 micromol/L of nickel and 0.16 micromol/L of cadmium) could induce the cleavage of DNA and activate PARP, and high levels of the two kinds of metal (2.00 - 10.00 micromol/L of nickel and 0.80 - 20.00 micromol/L of cadmium) could not induce the enzyme cleavage of DNA. CONCLUSION: Formation and cleavage of DNA double strand and blockage of activation of PARP can play an important role in carcinogenesis and mutagenesis.