Epstein-Barr virus-associated gastric cancer: A distinct subtype.

Epstein-Barr virus (EBV)-associated gastric cancer (EBVaGC) is a common malignant tumor associated with EBV infection. The molecular classification of gastric carcinoma indicates that EBVaGC is a distinct subtype in terms of oncogenesis and molecular features. Viral proteins, Bam-HI-A rightward transcripts (BART) miRNAs, and Bam-HI A rightward frame 1 (BARF1) promote oncogenesis after EBV infection via the induction of methylation, regulation of host gene expression, and malignant transformation. Together with abnormal mutations and amplification of the host genome as driving factors, interactions between the EBV genome and host genome accelerate carcinogenesis. The molecular profile of EBVaGC is that of EBV driving DNA hypermethylation, frequent phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) mutations, and the overexpression of Janus kinase 2 (JAK2), programmed death ligand-1 (PD-L1), and PD-L2. Clinically, the frequency of lymph node metastasis is lower, and the prognosis is better for EBVaGC than EBV-negative gastric cancer (EBVnGC). Pathologically, EBVaGC is a gastric adenocarcinoma with lymphoid stroma. This review interprets how the EBV genome is involved in the oncogenesis of gastric cancer and describes the molecular and clinicopathological features of EBVaGC.

Yang J ，Liu Z ，Zeng B ，Hu G ，Gan R ... -  《-》

Expression and prognostic roles of PIK3CA, JAK2, PD-L1, and PD-L2 in Epstein-Barr virus-associated gastric carcinoma.

As a special subtype of gastric carcinoma, Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) has distinct clinicopathological features. The Cancer Genome Atlas Research Network revealed that EBVaGC also has distinct molecular features: PIK3CA mutations, DNA hypermethylation, and JAK2, PD-L1, and PD-L2 amplification. Here, we evaluated PIK3CA, JAK2, PD-L1, and PD-L2 expression in 59 EBVaGC and 796 EBV-negative gastric carcinoma (EBVnGC) cases using immunohistochemistry and found that PIK3CA, JAK2, PD-L1, and PD-L2 were highly expressed in 75.9% and 48.8% (P<.001), 81.8% and 71.1% (P=.091), 92.5% and 84.8% (P=.132), and 98.1% and 89.7% (P=.049) of the EBVaGC and EBVnGC cases, respectively. However, the expression of PIK3CA, JAK2, PD-L1, or PD-L2 was not significantly associated with clinicopathological features or patient outcomes in EBVaGC. In contrast, in EBVnGC, high PIK3CA expression was significantly associated with indolent clinicopathological features and independently predicted better 5-year overall survival (57.8% versus 33.4%, P<.001). Our study indicated that the protein expression of the 4 characteristic molecules of EBVaGC was basically consistent with their genetic alterations, making them potential characteristic protein biomarkers and therapeutic targets of EBVaGC. The favorable impact of PIK3CA overexpression on survival found in this study gives us new insight into the clinical significance of PIK3CA in EBVnGC.

Dong M ，Wang HY ，Zhao XX ，Chen JN ，Zhang YW ，Huang Y ，Xue L ，Li HG ，Du H ，Wu XY ，Shao CK ... -  《-》

Epstein-Barr Virus-associated Gastric Cancer and Potential Mechanisms of Oncogenesis.

EBV-associated Gastric Cancer (EBVaGC) comprises about 9% of all cases of GC and constitutes a distinct clinicopathological and molecular entity. The pattern of viral expression in EBVaGC cannot be set to any of the previously EBV-associated malignancies. Several lines of evidence support that viral expression in EBVaGC is characterized by high transcription of the BamH1- A rightward transcript (BART), low-levels of EBNA-1 and lack of LMP1. The high transcription activity of the BamH1-A region is importantly directed to express BART miRNAs, supporting a critical role for these miRNAs during epithelial cell infection and carcinogenesis. Several studies have shown that promoter hypermethylation is also a prominent feature of EBVaGC. Based on the recent TCGA report, the specific fingerprint of genomic alterations in EBVaGC is marked by mutations in PIK3CA, ARID1A and BCOR genes, and amplification of 9p24.1 that harbors the genes for the JAK2, PD-L1 and PD-L2 proteins. The specific programs of viral gene expression, promoter methylation and genomic mutations found in EBVaGC target cell signaling pathways leading to increased proliferation, increased cell survival, immune evasion, augmented EMT and acquisition of stemness features. Less understood is the participation of EBV in chronic gastric inflammation, but some studies argue that EBV, similar to and together with Helicobacter pylori, is an early participant in the GC oncogenic process through promoting chronic inflammation and increased tissue damage. Here, we discuss the principal and distinctive carcinogenic routes promoted by EBV in the gastric epithelium.

Morales-Sanchez A ，Fuentes-Panana EM 《-》

Update on Epstein-Barr virus and gastric cancer (review).

Shinozaki-Ushiku A ，Kunita A ，Fukayama M 《-》

Gastritis-Infection-Cancer Sequence of Epstein-Barr Virus-Associated Gastric Cancer.

Fukayama M ，Kunita A ，Kaneda A 《Advances in Experimental Medicine and Biology》