AUTHOR=Zou Changyan , Liao Jinrong , Hu Dan , Su Ying , Lin Huamei , Lin Keyu , Luo Xingguan , Zheng Xiongwei , Zhang Lurong , Huang Tao , Lin Xiandong 

TITLE=SNHG8 Promotes the Progression of Epstein–Barr Virus-Associated Gastric Cancer via Sponging miR-512-5p and Targeting TRIM28

JOURNAL=Frontiers in Oncology

VOLUME=Volume 11 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2021.734694

DOI=10.3389/fonc.2021.734694

ISSN=2234-943X

ABSTRACT=SNHG8 has been reported to act as an oncogene in gastric carcinoma (GC). However, its biological function in Epstein-Barr virus-associated gastric cancer (EBVaGC) remains unclear.  This study investigated the role of SNHG8 in EBVaGC. 61 cases of EBVaGC , 20 cases of non-EBV-infected gastric cancer (EBVnGC) and relative cell lines were studied for the expression of SNHG8 and BHRF1 (BCL2 homolog reading frame 1) encoded by EBV with  Western blot and qRT-PCR assays . The relation-ship between the expression levels of SNHG8  and the clinical outcome in  61 EBVaGC cases was analyzed. Effects of over-expression or knock-down of BHRF1, SNHG8 or TRIM28 on cell prolif-eration，migration, invasion and cell cycle and the related molecules were determined by several assays, including  cell proliferation, colony assay，wound healing assay，transwell invasion assay, cell circle with flow cytometry, qRT-PCR and Western blot for expression levels, The  interactions among SNHG8, miR-512-5p and TRIM28 were determined with Luciferase reporter assay, RNA immunoprecipitation (RIP), pull-down assays and Western blot assay. The in vivo activity of  SNHG8 were assessed with  SNHG8 knockdown tumor xenografts in Zebrafish.
Results demonstrated that: (1) BHRF1 and SNHG8 was over-expressed in EBV-encoded RNA 1 positive EBVaGC tissues and cell lines. BHRF1 up-regulated the expressions of SNHG8 and TRIM28 in AGS; (2) SNHG8 over-expression had a significant correlation with tumor size  and vascular tumor thrombus. Patients with high SNHG8 expression had poorer overall survival (OS) compared to those with low SNHG8 expression; (3) SNHG8 over-expression promoted EBVaGC cell proliferation, migration and invasion  in vitro and in vivo,   cell cycle arrested at the G2/M phase via  the activation of BCL-2, CCND1，PCNA , PARP1, CDH1, CDH2  VIM  and Snail; (4) Results of dual-luciferase reporter assay, RNA immunoprecipitation and pull-down as says indicated that SNHG8 sponged miR-512-5p, which targeted on TRIM28 and promoted cancer malignant behaviors of  EBVaGC cells. Our data suggest that BHRF1 triggered expression of SNHG8, which  sponged miR-512-5p and up-regulated TRIM28 and a set of effectors (such as BCL-2, CCND1,CDH1, CDH2 Snail and VIM) to  promote EBVaGC tumorigenesis and invasion.   SNHG8 could be an independent prognostic factor for EBVaGC and sever as target for EBVaGC therapy.