HN protein of Newcastle disease virus sensitizes HeLa cells to TNF-α-induced apoptosis by downregulating NF-κB expression

Hemagglutinin neuraminidase (HN) is a membrane protein of Newcastle disease virus (NDV) with the ability to induce apoptosis in many transformed cell lines. TNF-alpha is a multi-factorial protein that regulates cell survival, differentiation and apoptosis. In a previous study, we reported that HN protein induces apoptosis by downregulating NF-kappa B expression. Further, we speculated that downregulation of NF-kappa B expression might sensitize HeLa cells to TNF-alpha-mediated apoptosis. Therefore, the present study was undertaken to investigate if HN protein could sensitize HeLa cells to TNF-alpha and to examine the apoptotic potential of the HN protein and TNF-alpha in combination. The results revealed that the pro-apoptotic effects were more pronounced with the combination of HN and TNF-alpha than with HN or TNF-alpha alone, which indicates that the HN protein indeed sensitized the HeLa cells to TNF-alpha-induced cell death. The results of the study provide a mechanistic insight into the apoptotic action of HN protein along with TNF-alpha, which could be valuable in treating tumor types that are naturally resistant to TNF-alpha.