Abstract:

Abstract: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-1CdCl₂ 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 (IC₅₀=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.

Key words: cadmium chloride;human hepatocarcinoma cells;proliferating cell nuclear antigen;metallothionein