Epstein-Barr Virus Latent Membrane Protein 2A (LMP2A) Enhances ATP Production in B Cell Tumors through mTOR and HIF-1α.

ABSTRACT

Epstein-Barr Virus (EBV) exists in a latent state in 90% of the world's population and is linked to numerous cancers, such as Burkitt's Lymphoma, Hodgkin's, and non-Hodgkin's Lymphoma. One EBV latency protein, latency membrane protein 2A (LMP2A), is expressed in multiple latency phenotypes. LMP2A signaling has been extensively studied and one target of LMP2A is the mammalian target of rapamycin (mTOR). Since mTOR has been linked to reprogramming tumor metabolism and increasing levels of hypoxia-inducible factor 1 α (HIF-1α), we hypothesized that LMP2A would increase HIF-1α levels to enhance ATP generation in B lymphoma cell lines. Our data indicate that LMP2A increases ATP generation in multiple Burkitt lymphoma cell lines that were dependent on HIF-1α. Subsequent studies indicate that the addition of the mTOR inhibitor, rapamycin, blocked the LMP2A-dependent increase in HIF-1α. Further studies demonstrate that LMP2A does not increase HIF-1α levels by increasing HIF-1α RNA or STAT3 activation. In contrast, LMP2A and mTOR-dependent increase in HIF-1α required mTOR-dependent phosphorylation of p70 S6 Kinase and 4E-BP1. These findings implicate the importance of LMP2A in promoting B cell lymphoma survival by increasing ATP generation and identifying potential pharmaceutical targets to treat EBV-associated tumors.