LYMPHOID NEOPLASIA Lymphomas differ in their dependence on Epstein-Barr virus

Epstein-Barr virus (EBV) encodes oncogenic information and, oftentimes concomitant with host immunosuppression, gives rise to malignancies in all major categories of lymphoma defined by the World Health Organization.1 Here, we conditionally evicted the viral extrachromosomal genome from tumor cells in vitro to examine the role of EBV in different lymphomas, including Burkitt lymphoma (BL) and posttransplant lymphoproliferative disorder. Cells derived from 2 canonical BLs were found to have the least dependence on the virus; some required EBV to prevent the inefficient induction of apoptosis. In contrast, cells derived from a subset of BL, Wp-restricted BL, required EBV to block a robust apoptotic program that involves the up-regulation of the proapoptotic protein Bim. Wp-restricted BL cells also relied on the virus to promote efficient proliferation, a distinction that highlights the multiple contributions EBV makes to affect proliferation of its host cells. Like Wp-BL cells, posttransplant lymphoproliferative disorder cells depended on the virus to inhibit apoptosis. They furthermore required the virus to drive them out of G1/G0. Together, these results reveal a graded dependence on EBV among tumor cells that directly correlates with the number of viral genes expressed in the tumor cell. (Blood. 2011;117(6):1977-1985)