Identification of novel cellular and viral inhibitors in gammaherpesvirus-associated malignancies.

摘要

The human gammaherpesviridae Kaposi's Sarcoma Herpesvirus (KSHV) and Epstein-Barr Virus (EBV) have evolved to subvert various cellular pathways in the infected host to favor malignant transformation. Our work shows that malignant cell dependency on these aberrantly regulated pathways may be exploited to kill the transformed cell, and prevent disease progression in mouse models. Additionally, we employed novel screening methods and libraries to identify virus-specific hits that show promise for further development in the laboratory.;The molecular chaperone Hsp90 has garnered attention as a therapeutic modality for cancer recently, due to the critical role it plays in the stabilization of proteins and complexes crucial to the malignant cell. We exploited a novel non-quinone inhibitor of Hsp90 to extensively determine the effects of Hsp90 inhibition on KSHV-infected primary effusion lymphoma (PEL) cells. Our results showed Hsp90 inhibition was effective against PEL in vitro and in vivo, acting at least in part through the destabilization of critical viral oncogene vFLIP, resulting in concomitant destabilization of the NF-kappaB pathway that is essential to the survival of PELs. The discovery of Hsp90 control of vFLIP stability and transcription is novel.;Finally, we employed complementary approaches to discover specific viral and cellular inhibitors for KSHV and EBV, including in silico screens based on viral oncogene interactions, and cellular assays based on the disruption of NF-kappaB, which is essential to both KSHV- and EBV- associated lymphoma survival. Screening of conventional and biased libraries led to the identification of hits that disrupt oncogenic pathways in a viral cell-specific manner, which warrant further study in the laboratory.;Our results from Hsp90 inhibition, reactive oxygen species (ROS) disruption, and oncogene-specific NF-kappaB inhibition suggested various complementary treatment modalities may be considered promising for translation to the clinic. The future of KSHV and EBV therapy is likely to be targeted combinatorial therapy employing inhibitors of cellular and viral pathways in a multi-hit manner to destabilize malignant cells addicted to these pathways.