Aim: To determine whether interferon-α (IFNα) can enhance doxorubicin sensitivity in osteosarcoma cells and its molecular mechanism. Methods: Cell viability was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis was studied using Flow cytometry analysis, Hoechst33258 staining, DNA fragmentation assay, as well as the activation of caspase-3 and poly (ADP-ribose) polymerase. Protein expression was detected by Western blotting. The dependence of p53 was determined using p53-siRNA transfection. Results: IFNα increased doxorubicin-induced cytotoxicity to a much greater degree through apoptosis in human osteosarcoma p53-wild U2OS cells, but not p53-mutant MG63 cells. IFNα markedly upregulated p53, Bax, Mdm2, and p21, downregulated Bcl-2, and activated caspase-3 and PARP cleavage in response to doxorubicin in U2OS cells. Moreover, the siRNA-mediated silencing of p53 significantly reduced the IFNα/doxorubicin combination-induced cytotoxicity and PARP cleavage. Conclusion: IFNα enhances the sensitivity of human osteosarcoma U2OS cells to doxorubicin by p53-dependent apoptosis. The proper combination with IFNα and conventional chemotherapeutic agents may be a rational strategy for improving the treatment of osteosarcoma with functional p53.
The tumor suppressor p14ARF, encoded by the INK4a/ARF locus, is often disrupted in human cancers. p14ARF triggers cell cycle arrest and sensitizes cells to apoptosis in the presence of collateral signals. To investigate the role of p14ARF in chemotherapeutic drugs-induced apoptosis, p14ARF was overexpressed by stable transfection in human osteosarcoma cell lines, U2OS (p53-wt/p14ARF-null) and MG63 (p53-mt/p14ARF-null). The results showed that ectopic p14ARF sensitized both cell lines to cisplatin-induced cytotoxicity and apoptosis. This sensitization of cisplatin-induced apoptosis was associated with upregulation of p53, Bax and p21 in U2OS cells. Conversely, such a result was not observed in MG63 cells. Moreover, the sensitization of cisplatin-induced cytotoxicity in U2OS cells was unaltered by p53 siRNA. Together, we show here p14ARF sensitizes human osteosarcoma cells to cisplatin-induced apoptosis in a p53-independent manner. Proper combinations of p14ARF gene transfer and conventional chemotherapy may be a valuable strategy in human osteosarcoma treatment.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.