cytochrome-c-t and veliparib

To explore inhibition effects of veliparib as PARP inhibitor combined doxorubicin for BEL-7404 proliferation of human liver cancer cell line.. BEL-7404 was taken as the object of study and conventional culture was performed. It was treated by doxorubicin and (or) veliparib after 24 h. Cell proliferation rate was detected by four methyl thiazolyl tetrazolium (MTT) assay, cell apoptosis was measured with annexin V-FITC/PI double staining method by flow cytometry, DNA damage degree evaluation by single cell gel electrophoresis assay, and cytosolic C levels of the mitochondrial and cytosol by polyacrylamide gel electrophoresis (Western blotting).. Cell proliferation rate of doxorubicin combined veliparib group was lower than that of the control group and doxorubicin alone treated group significantly (P<0.01), the apoptosis rate was significantly higher than that of the control group and doxorubicin alone treated group (P<0.05). At the same time, DNA damage level of doxorubicin combined with veliparib group was significantly higher than doxorubicin alone treatment group and the control group (P<0.01), and cytochrome C in the cytosol was significantly higher than that of control group and doxorubicin alone treated group (P<0.01).. Veliparib, PARP inhibitor could inhibit PARP activity, block tumor cell DNA repair, and have significant sensitizing effect for hepatocellular carcinoma cell line BEL-7404 treated with doxorubicin. This might provide a new target for clinical treatment of hepatic carcinoma.

Topics: Antineoplastic Agents; Apoptosis; Benzimidazoles; Cell Line, Tumor; Cell Proliferation; Cytochromes c; DNA Damage; Doxorubicin; Humans; Liver Neoplasms

Majority of chemotherapeutic agents inhibit tumor growth by inducing apoptosis or necrosis. The DNA alkylating agent, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), kills cells by necrosis through massive production of DNA strand breaks and subsequent over-activation of PARP. Inhibition of PARP, either through PARP1 genetic ablation or through small molecule PARP inhibitors, protected MNNG-induced cell death in certain cell types including MEF and primary cortical cultures. We report here that a potent PARP inhibitor, ABT-888, facilitates the induction of apoptotic cell death in HeLa cells treated with MNNG. Although the release of cytochrome c from mitochondria to cytosol was observed in HeLa cells treated with either MNNG alone or the combination of MNNG and ABT-888 (MNNG/ABT-888), apoptosis is observed only in HeLa cells treated with MNNG/ABT-888. Bcl-2 family proteins regulate the release of cytochrome c. Downregulation of Bax and Bak by their corresponding siRNAs or overexpression of Bcl-xl inhibited the release of cytochrome c from mitochondria to cytosol, and inhibited apoptosis induced by MNNG/ABT-888. Further examination indicates that ATP concentration is greatly reduced in HeLa cells treated with MNNG alone, but not in HeLa cells treated with MNNG/ABT-888. Reduction of ATP concentration by F0F1-ATP synthase inhibitor oligomycin A renders HeLa cells resistant to the apoptosis induction by treatment with MNNG/ABT-888. Unlike in HeLa cells, ABT-888 protected MNNG induced cell death in normal human fibroblasts. Our study provides evidence that PARP activity determines the fate of HeLa cells by regulating the level of ATP after treatment with MNNG.

Topics: Alkylating Agents; Animals; Apoptosis; Benzimidazoles; Cytochromes c; DNA Damage; Fibroblasts; Gene Expression Regulation, Enzymologic; HeLa Cells; Humans; Methylnitronitrosoguanidine; Mice; NAD; Oligomycins; Poly(ADP-ribose) Polymerases