Abstract 1006: TP53-induced glycolysis and apoptosis regulator (TIGAR) induces NADPH production and growth in nasopharyngeal carcinoma cells

Abstract

Abstract TIGAR (TP53-induced glycolysis and apoptosis regulator) is a novel dual regulator of glycolysis and apoptosis regulated by p53. TIGAR was first found to protect normal cells from oxidative stress by inducing cellular production of NADPH, a powerful reducing agent in the cell, via the pentose phosphate shunt. Nasopharyngeal carcinoma (NPC) is a highly metastatic head and neck cancer prevalent in Southeast Asia. Our previous studies demonstrated that overexpression of TIGAR rescued NPC cells from growth inhibition induced by c-Met kinase inhibitors and an RNA anti-metabolite (ECyd), suggesting an anti-apoptotic function of TIGAR in NPC. Here, we demonstrated by Western blotting and immunohistochemistry that TIGAR was expressed in primary tumor biopsies of NPC. Moreover, NPC cell lines from various differentiation status also expressed TIGAR. Using an Epstein-Barr virus-associated NPC cell line, HONE-1-LMP1 cells, we showed that specific knockdown of TIGAR by siRNA inhibited cell proliferation (∼45%) at 48 hrs. Moreover, TIGAR overexpression markedly increased NPC cell proliferation (>300%), which was accompanied by significant induction of cellular NADPH production (>200%). This indicates that TIGAR-induced generation of NADPH, which is an important building block for major cellular metabolites for proliferation (including DNA, RNA and fatty acids, etc), may be involved in NPC carcinogenesis. Furthermore, TIGAR overexpression induced the expression of a pro-survival protein, Mcl-1 in NPC cells, which supports an anti-apoptotic function of TIGAR in NPC. Our results implicate that TIGAR may confer survival benefits to NPC cells via metabolic alteration. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1006. doi:10.1158/1538-7445.AM2011-1006