Interferon-α enhances sensitivity of human osteosarcoma U2OS cells to doxorubicin by p53-dependent apoptosis

Aim:To determine whether interferon-α(IFNα) can enhance doxorubicinsensitivity in osteosarcoma cells and its molecular mechanism.Methods:Cellviability was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assay.Apoptosis was studied using Flow cytometry analysis,Hoechst33258 staining,DNA fragmentation assay,as well as the activation ofcaspase-3 and poly (ADP-ribose) polymerase.Protein expression was detectedby Western blotting.The dependence of p53 was determined using p53-siRNAtransfection.Results:IFNα increased doxorubicin-induced cytotoxicity to a muchgreater degree through apoptosis in human osteosarcoma p53-wild U2OS cells,but not p53-mutant MG63 cells.IFNα markedly upregulated p53,Bax,Mdm2,andp21,downregulated Bcl-2,and activated caspase-3 and PARP cleavage in re-sponse to doxorubicin in U2OS cells.Moreover,the siRNA-mediated silencing ofp53 significantly reduced the IFNα/doxorubicin combination-induced cytotoxic-ity and PARP cleavage.Conclusion:IFNα enhances the sensitivity of humanosteosarcoma U2OS cells to doxorubicin by p53-dependent apoptosis.The propercombination with IFNα and conventional chemotherapeutic agents may be a ra-tional strategy for improving the treatment of osteosarcoma with functional p53.