The Epstein Barr Virus (EBV) is an oncogenic gamma-herpesvirus that is associated with Hodgkin disease and anaplasmic nasopharyngeal carcinoma. EBV infection is particularly hazardous with advanced HIV disease or transplant, where EBV-encoded proteins drive aberrant cell growth in the absence of immune surveillance. The principal EBV oncogene, Latent Membrane Protein 1 (LMP1), promotes cell survival and proliferation by mimicking activated immune receptors. Through incompletely defined pathways, LMP1 potently stimulates Nuclear Factor Kappa B (NF-kB), transcription factors that control inflammation, cell survival and growth. EBV- transformed cells rely on constitutive NF-kB activation, and rapidly undergo apoptosis upon NF-kB blockade. Side-effects preclude the clinical use of currently available NF-kB inhibitors, though LMP1-selective drug targets may afford substantially less toxicity. It is therefore important to define how LMP1 activates NF-kB. I have carried out a human genome-wide siRNA screen for cellular modulators of LMP1 canonical NF-kB activation. Hits that either suppress or enhance LMP1 activation of NF-kB have been validated with secondary screens. The screens have implicated numerous proteins in LMP1 function, including novel factors not previously associated with NF-kB. I will carry out hypothesis-based and larger-scale secondary assays to identify critical missing components of LMP1 NF-kB activation in both epithelial cells and B lymphoblasts. I will pursue detailed biochemical analysis of several targets of particular interest, including potentially druggable enzymes and functionally clustered hits. Secondary screens will further stratify hits into functional groups based on whether they affect LMP1 expression, subcellular trafficking, and where they function within the LMP1/NF-kB pathway. Cellular factors uniquely employed by LMP1, but not by immune receptor pathways, may serve as important therapeutic targets for treatment of EBV-driven malignancies. Likewise, these studies may reveal important general mechanisms of NF-kB activation, with implications for allergy, autoimmunity, and host-defense.
Persistent Epstein Barr virus infection is an important cause of certain lymphoma and throat cancers. This project will better define how EBV subverts cellular machinery to drive cancerous growth of infected cells. Ultimately, it is hoped that knowledge gained from these studies may enable the development of chemotherapies that specifically block EBV function.
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