A STING inhibitor suppresses EBV-induced B cell transformation and lymphomagenesis.

Epstein-Barr virus-associated lymphoproliferative disease (EBV-LPD) is frequently fatal. Innate immunity plays a key role in protecting against pathogens and cancers. The stimulator of interferon genes (STING) is regarded as a key adaptor protein allowing DNA sensors recognizing exogenous cytosolic DNA to activate the type I interferon signaling cascade. In terms of EBV tumorigenicity, the role of STING remains elusive. Here we showed that treatment with the STING inhibitor, C-176, suppressed EBV-induced transformation in peripheral blood mononuclear cells. In an EBV-LPD mouse model, C-176 treatment also inhibited tumor formation and prolonged survival. Treatment with B cells alone did not affect EBV transformation, but suppression of EBV-induced transformation was observed in the presence of T cells. Even without direct B cell-T cell contact in a transwell system, the inhibitor reduced the transformation activity, indicating that intercellular communication by humoral factors was critical to prevent EBV-induced transformation. These findings suggest that inhibition of STING signaling pathway with C-176 could be a new therapeutic target of EBV-LPD.