PD-L1 overexpression in EBV-positive gastric cancer is caused by unique genomic or epigenomic mechanisms

Abstract Epstein-Barr virus-positive gastric cancer [EBV (+) GC] is a distinct GC subtype with unique genetic and epigenetic aberrations. Here, we examined resected samples publicly available microarray data The Cancer Genome Atlas (TCGA) database to identify the mechanism underlying overexpression of PD-L1 in EBV GC. We found that high levels were caused by focal amplification CD274 . By contrast, relatively expression tumor tissue infiltrating immune cells correlated CD8 lymphocyte infiltration IFN-γ via IRF3 activation. Since reported previously associated both presence T microenvironment GC, see whether IFN-γ-associated plays significant role Immunohistochemical staining showed signature clinical was higher than (−) cases. presented herein reveal dual GC: or IFN-γ-mediated signaling activation IRF3.