The GAGE family of highly related tumor antigens is expressed in a variety of tumors. This albeit silent gene expression resulted in resistance of cells to various apoptotic agents such as Fas, interferon-γ, Taxol, or γ-radiation. We now report that GAGE overexpression in either HeLa (expressing endogenous GAGE) or HEK293 (devoid of GAGE expression) rendered those cells unsusceptible to cell death induced by IFN-γ. We investigated the underlying mechanism of GAGE-induced cell survival upon treatment with IFN-γ in this report. We showed that GAGE overexpression resulted in down-regulation of a key player of IFN-γ-signaling pathway, interferon regulatory factor 1 (IRF1), and its target genes caspase-1 and caspase-7. An interaction between GAGE and IRF1 is detected in cells. Furthermore, GAGE interacted with a multifunctional protein nucleophosmin (NPM)/B23 and increased its abundance by stabilizing the protein. Increased level of NPM/B23 in conjunction with decreased level of IRF1 could aid GAGE-induced resistance to IFN-γ. Our results suggest that GAGE could rescue cell death induced by IFN-γ by altering the level of key players in cell death pathways. As GAGE is silent in most healthy tissues, targeting GAGE could result in therapeutic interventions in cancer therapy.
ASJC Scopus subject areas
- Cell Biology