Epstein-Barr virus-encoded microRNA-BART17-5p suppresses cell proliferation and metastasis by targeting CERK.

Epstein-Barr virus (EBV) is an oncogenic DNA virus that is etiologically associated with multiple malignancies, including nasopharyngeal carcinoma, gastric carcinoma, and lymphomas. Although EBV encodes numerous viral microRNAs (miRNAs), the pathogenic functions of individual miRNAs remain incompletely characterized. In this study, we identify EBV-encoded miR-BART17-5p as a tumor-suppressive miRNA that directly targets ceramide kinase (CERK). CERK expression is significantly downregulated in EBV-associated gastric cancer (EBVaGC) tissues and EBV-positive AGS-EBV cells and inversely correlates with miR-BART17-5p levels. Mechanistic analyses further demonstrate that miR-BART17-5p directly targets the 3' untranslated region (3'UTR) of CERK, thereby regulating its expression. Overexpression of miR-BART17-5p mimics or knockdown of CERK in AGS cells significantly suppresses tumor -associated phenotypes, including cell proliferation, migration, and invasion. Conversely, inhibition of miR-BART17-5p in AGS-EBV cells rescues these phenotypes. Similar results were obtained in SNU719 cells. Mechanistically, miR-BART17-5p inhibits the PI3K/AKT signaling by targeting CERK. Restoration of CERK expression reactivates PI3K/AKT signaling and reverses the inhibitory effects on cell proliferation, migration, and invasion in AGS cells. To evaluate the therapeutic potential of miR-BART17-5p, systemic administration of engineered cholesterol-conjugated miR-BART17-5p agomirs significantly suppresses tumor growth in xenograft models. Collectively, our findings reveal a previously unrecognized EBV-host interaction whereby miR-BART17-5p constrains cancer progression through modulation of CERK/PI3K/AKT signaling activation, highlighting its potential as a preclinical therapeutic strategy for cancer.