Interferon alpha induces the apoptosis of cervical cancer HeLa cells by activating both the Intrinsic Mitochondrial pathway and ER Stress-induced pathway

The interferon alpha (IFN-α) has been used for treatment of various malignancies such as hepatocellular carcinoma (HCC), malignant melanoma and renal cell cancer (RCC), and has been shown to promote the apoptosis and inhibit the growth of several tumor cell types. However, the effect of IFN-α on cervical cancer is completely unknown. In this study, HeLa cells were used as a testing model for the treatment of IFN-α on cervical cancer. The results indicate that IFN-α could markedly inhibit the proliferation and induce the apoptosis of HeLa cells. The activation of caspase 3, the up-regulation of Bim and the cleaved PARP1, the down-regulation of Bcl-xL as well as the release of cytochrome C from mitochondria to cytosol were significantly induced upon IFN-α treatment. In addition, caspase 4 which is implicated in ER stress-induced apoptosis was cleaved with IFN-α treatment. Knockdown of caspase 4 by siRNA markedly reduced the cell apoptosis rate, but not affected the mitochondrial apoptotic pathway. Moreover, no significant changes on he expression of caspase 8, caspase 10, Fas/Fas-L were observed upon IFN-α treatments, indicating the apoptosis caused by IFN-α may be independent of extrinsic apoptotic pathway. These findings suggest that IFN-α may possess the capacity of an anti cervical cancer compound by mainly activating both the intrinsic mitochondrial pathway and ER stress-induced pathway.