The Primary Study On The Molecular Mechanism Of DNA Damage In MCF-7Cell By Cisplatin

Breast cancer is one of the most common female malignant tumors. Cisplatin, one of the most effective chemotherapy medicines to breast cancer, is now widely used in clinical for a variety of cancers. In this study, with the analysis of expression of relative proteins in the DDP inducible breast cancer cell line MCF-7, we investigated the molecular mechanism for DDP in DNA damage repair signaling pathway.MTT assay was used to detect the growth inhibition of DDP to cancer cells and the IC50was measured. The use of the corresponding medicine concentrations to treat cell line MCF-7for different time and immunofluoescence histochemistry analysis revealed that after treatment for6hours of DDP to MCF-7cell line, the DNA damage marker γ-H2AX was detected and the result of western blotting indicated the expression level increased. RT-PCR showed the other DNA damage repair gene, such as p53, p27, p21were all up regulated but except atm and chk2. We also found phosphorylated ATM, Chk2were significantly increased in comparison to the control by studying the expression of DNA damage repair proteins after DDP interference. Nevertheless, the protein expression of P53, P27and P21were firstly up-regulated then down-regulated, different from the gene expression changes, which suggested the possibility that the cells made apoptosis as the medicine action, thus some key proteins were degradated. Therefore, we futher investigated the apoptosis in DDP treatment MCF-7cells. In these cells, the hochest33258stain and the expression of Caspase-3protein suggested the apoptosis was significantly found after36hours of DDP treatment in cells. These results indicated that the DDP can induce DNA double-strand break when acted to MCF-7cell line and finally to kill the cells by DNA damage repair mediated apoptosis.