Comprehensive profiling of virus microRNAs of Epstein–Barr virus-associated gastric carcinoma: highlighting the interactions of ebv-Bart9 and host tumor cells

Background and Aim: Epstein–Barr virus (EBV) is suggested to actively utilize its ebv-microRNAs (miRNAs) to manipulate viral and cellular functions during neoplasia transformation. A systemic profiling of ebv-miRNAs expressed in EBV-associated gastric carcinoma (EBVa GC) helps understand its epigenetic regulation of carcinogenesis. Methods: A total of 1039 patients with gastric cancer were screened for EBVa GC using EBV-encoded RNAs in situ hybridization. A comprehensive profiling of ebv-miRNAs expressed in EBVa GC was constructed using stem-loop quantitative polymerase chain reaction. Functional assay of specific ebv-miRNA was conducted. Expression of epithelial-to-mesenchymal transition (EMT) markers among EBVa GC and non-EBVa GC was compared. Results: The prevalence of EBVa GC was 5.0% (52 out of 1039) in our series. The most abundant ebv-miRNAs of EBVa GC were Bart4, followed by Bart11, Bart2, Bart6, Bart9, and Bart18, in the decreasing order. Of them, Bart9 exhibited the same seed sequence as to hsa miR-200a and miR-141. Expression of E-cadherin of EBV-positive SNU-719 was increased after BART9 knockdown. Depleting endogenous Bart9 of SNU-719 induced a surged expression of miR-200a and miR-141, accompanied by decreased proliferative and invasive ability. Expression of mesenchymal markers in EBVa GC was increased compared with those of non-EBVa GC, albeit the two cohorts exhibited a comparable long-term survival. Conclusions: We constructed a comprehensive profiling of ebv-miRNAs in EBVa GC. BART9 plays an important role during carcinogenesis through EMT. Inherent mesenchymal phenotype of EBVa GC represents a unique virus-induced morphology and microenvironment rather than being able to predict the prognosis.