Epstein-Barr virus BRRF1 induces butyrophilin 2A1 in nasopharyngeal carcinoma cells via the IL-22/JAK3-STAT3 pathway

Epstein-Barr virus is highly associated with nasopharyngeal carcinoma (NPC) with genes expressed for tumor transformation or maintenance of viral latency, but there are certain genes that can modulate immune molecules. Butyrophilin 2A1 (BTN2A1) is an important activating protein for presenting phosphoantigen presentation for recognition by Vγ9Vδ2 T cells to achieve anti-tumor activities. We have previously shown that Vγ9Vδ2 T cells achieve efficacy against NPC when BTN2A1 and BTN3A1 are upregulated by stimulating EBV gene expression, particularly LMP1. Whilst BTN3A1 can be induced by LMP1 mediated IFN-γ/JNK/NLRC5 pathway, the viral gene that can regulate BTN2A1 remains elusive. Here, we showed that BTN2A1 expression is directly mediated by EBV BRRF1, which can trigger BTN2A1 promoter and downstream JAK3-STAT3 pathway in NPC43 cells as enlightened by RNA-seq data and verified by inhibitor experiments. Further, BRRF1 downregulated IL-22 binding protein (IL-22RA2) to complement the EBNA1-targeting probe (P4) induced IL-22 expression. These functions act in concordance to enhance the expression of BTN2A1, which likely lead to increased tumor cell killing by Vγ9Vδ2 T cells. Overall, this study elucidated a new mechanism of stimulating BTN2A1 expression in nasopharyngeal carcinoma cells by the EBV gene BRRF1.