HN protein of Newcastle disease virus sensitizes HeLa cells to TNF-[alpha]-induced apoptosis by downregulating NF-[kappa]B 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].