Abstract 1512: Role of Epstein-Barr virus in nasopharyngeal carcinoma under metabolic stress.

Abstract Most nasopharyngeal carcinoma (NPC) biopsies contain a human pathogen named as Epstein-Barr virus (EBV). EBV infection is considered as an early event involved in the pathogenesis of NPC. However, the close association of EBV with NPC is a paradox. EBV infection is common that occurs in ≥95% of the world's population, yet the incidence rate of NPC is rare worldwide and is only seen in Cantonese speaking ethnic groups in Southern Asia. The mechanisms that regulate EBV infection of NPC/pre-malignant NP cells including the events involved in latency and lytic activation (either in vitro or in vivo) are not well-defined. Expressions of latent and lytic EBV genes have been shown to have variable effects on the biology and malignant properties of EBV-infected cells. Hypoxia and nutrient-starvation are common physiological stresses within tumours and may have impact on regulation of latent and lytic EBV infection in NPC cells. Here we report that the levels of hypoxia-inducible factor, HIF-1α protein, a prime hypoxic-stress responsive marker for mammalian cells, are higher in EBV-infected NPC/pre-malignant NP cell lines under hypoxia than their non-infected counterparts, which may imply an enhanced survival ability of EBV-infected NP cells. The alteration in gene expression profiles of host cells and expression of EBV genes observed in infected cells may be responsible for the stabilization of HIF-1α and vice versa. Moreover, EBV infection enhances the tumour growth rate and size of NPC cells xenografts in nude mice. The main stem of this study is to examine whether there is a differential response between EBV-infected and non-infected NP cells towards various metabolic stresses. Through studying this project, the mechanism and function of HIF-1α stability by EBV infection will be explored, which is expected to help characterizing the role of EBV in transformation of epithelial cells and how EBV infection may enhance NPC cells to survive inside a tumour core. Citation Format: VMY Lau, SW Tsao. Role of Epstein-Barr virus in nasopharyngeal carcinoma under metabolic stress. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1512. doi:10.1158/1538-7445.AM2013-1512 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.