Gamma Interferon-Inducible Protein 10 Induces HeLa Cell Apoptosis through a p53-Dependent Pathway Initiated by Suppression of Human Papillomavirus Type 18 E6 and E7 Expression

Abstract

Gamma interferon-inducible protein 10 (IP10) is a member of the CXC family of chemokines. By differential mRNA display, we have demonstrated the upregulation of IP10 in coxsackievirus B3 (CVB3)-infected mouse hearts. Functional characterization of the IP10 gene in IP10-transfected Tet-On HeLa cells has found that IP10 induced cell apoptosis and inhibited viral replication. In the characterization of the IP10-induced apoptotic pathway, we found that overexpression of IP10 upregulated p53 and resulted in altered expression of p53-responsive genes such as the p21^Cip1, p27^kip1, NF-κB, Bax, and PUMA genes and the mitochondrial translocation of Bax. However, transduction of the IP10 cells with adenovirus expressing dominant negative p53 not only ablated p53-triggered gene expression but also abolished IP10-induced apoptosis and restored CVB3 replication to the control levels. These data suggest a novel mechanism by which IP10 inhibits viral replication through the induction of host cell death via a p53-mediated apoptotic pathway. We also found that constantly high-level expression of p53 in these tumor cells is attributed to the IP10-induced suppression of human papillomavirus E6 and E7 oncogene expression. Taken together, these data reveal not only a previously unrecognized link between chemokine IP10 and p53 in antiviral defense but also a mechanism by which IP10 inhibits tumor cell growth.

ACKNOWLEDGMENTS

We thank Thomas Hamilton, Research Institute, Cleveland Clinic Foundation, for providing us the murine cDNA of IP10. We also thank John Lai, Travis Lim, and Zongshu Luo for their contributions to certain experiments and preparation of the manuscript.

These studies were supported by grants from the Heart and Stroke Foundation of British Columbia and Yukon and the Canadian Institutes of Health Research.