氯化镉对人癌细胞株的抑制作用及其对细胞增殖核抗原和金属硫蛋白表达的影响

Inhibitory effects of cadmium chloride on human cancer cells and influence in proliferation cell nuclear antigen and metallothionein expressions

目的:研究氯化镉(CdCl2)抗肿瘤作用及其对细胞增殖核抗原(PCNA)和金属硫蛋白(MT)表达的影响,为其作为抗肿瘤药的开发利用提供理论依据。方法:以1、5、10、50和100μmol.L-1 CdCl2作用于5种人癌细胞株SMMC-7721、BEL-7402、Hela、A549和MCF7,24h后应用MTT法检测抑瘤效应;以5、10、20、40和80μmol.L-1 CdCl2作用于SMMC-7721细胞24、48和72h,MTT法检测时间-剂量-效应关系,SCGE法检测其对人肝癌细胞SMMC-7721的DNA损伤作用,应用免疫细胞化学法检测PCNA和MT的表达。结果:CdCl2对人肝癌SMMC-7721细胞半数抑制浓度最低(IC50=12.43mL-1),随着CdCl2浓度增加和作用时间延长,40和80μmol.L-1剂量组抑制作用逐渐增强,与对照组比较,差异有统计学意义(P<0.05),且存在时间-剂量-效应关系。与对照组比较,CdCl2作用12和24h时,各剂量组SMMC-7721细胞DNA损伤率明显增加(P<0.05或P<0.01),但80μmol.L-1组DNA损伤率反而下降;与对照组比较,各剂量组PCNA的表达明显下降(P<0.05或P<0.01);人肝癌细胞SMMC-7721中几乎不表达MT,CdCl2可诱导其MT的表达且具有剂量-效应关系。结论:CdCl2在体外具有显著的抗肿瘤效应,可能通过诱导DNA损伤、抑制PCNA蛋白的表达进而影响肿瘤细胞增殖;CdCl2可诱导MT产生部分拮抗作用。

Objective To study the anti-tumor effects of cadmium chloride（CdCl2） and the influence in proliferating cell nuclear antigen（PCNA） and metallothionein（MT） expressions,and to provide theoretical basis for development of CdCl2 as anti-tumor drug.Methods Five kinds of carcinoma cell lines,SMMC-7721,BEL-7402,Hela,A549 and MCF7 were treated with 1,5,10,50 and 100 μmol·L-1 CdCl2 for 24 h,MTT assay was used to measure the inhibitory rate.SMMC-7721 cells were treated with 5,10,20,40 and 80 μmol·L-1CdCl2 for 24,48 and 72 h,MTT assay was used to detect the time-dose-effect relationship.SCGE was applied to observe DNA damage.Immunocytochemistry assay was performed to detect positive expressions of PCNA and MT.Results The malignant hepatocarcinoma SMMC-7721 cell line showed a significant sensitivity to CaCl2 with a time-dose-effect relationship（IC50=12.43 m L-1）.Compared with control group,the inhibitory rates in 40 and 80 μmol·L-1 groups were significantly decreased（P〈0.01）.Compared with control group,after treated with CdCl2 for 12 and 24 h,the DNA damage rates in CdCl2 groups were increased（P〈0.05 or P〈0.01） with the increase of CdCl2 except for 80 μmol·L-1 group.Compared with control group,the expressions of PCNA in CdCl2 groups were decreased（P〈0.05 or P〈0.01） with the increasing of CdCl2.SMMC-7721 could hardly express MT,but the expression could be induced by CdCl2 with a dose-effect relationship.Conclusion CdCl2 shows a significant anti-tumor effects in vitro,and cause proliferation depression through inducing DNA damage and inhibiting PCNA protein expression,and its side effects may be alleviated by inducing MT expression.