Background: An increasing body of evidence indicates that miRNAs have a critical role in carcinogenesis and cancer progression; however, the role of miRNAs in the tumorigenesis of adencarcinoma of gastric esophageal junction(AGEJ) remains largely unclear.Methods: The SGC7901 and BGC-823 gastric cancer cell lines were used. The expressions of miR-645 and IFIT2 were examined by qRT-PCR. The expressions of IFIT2 was examined by western blotting and immunohistochemistry assay. The cell apoptosis was determined by FACS. MiR-645 inhibitor, mimics and plasmid-IFIT2 transfections were performed to study the loss- and gain-function. Caspase-3/7 activity was examined by caspase-3/7 assay. Results: In the present study, we have reported an increased expression of miR-645 in AGEJ clinical specimens compared with paired non-cancerous tissues. We also observed a significant miR-645 up-regulation in two gastric cancer ( GC ) cell lines, SGC7901 and BGC-823, which were used as cell models because there was no available AGEJ cell lines established to date. We found that inhibition of miR-645 could sensitize dramatically SGC7901 and BGC-823 cells to both serum starvation- and chemotherapeutic drug-induced apoptosis by up-regulating IFIT2, a mediator of apoptosis via a mitochondrial pathway, with a potential binding site for miR-645 in its mRNA's 3′UTR. Further investigation exhibited that IFIT2 expression decreases in SGC7901 and BGC-823 cells and AGEJ tissues. IFIT2 ectopic expression leads to promotion of cell apoptosis, indicating that IFIT2 may function as a suppressor in the development of AGEJ. Furthermore, inhibition of miR-645 induces up-regulation of IFIT2 and increased caspase-3/7 activity compared with control groups. Conclusions: Our data suggest that miR-645 functions as an oncogene in human AGEJ by, at least partially through, targeting IFIT2. <!–EndFragment–>

Note: This abstract was not presented at the meeting.

Citation Format: Xiaoshan Feng, Ying Wang, Zhikun Ma, Ruina Yang, Mengxi Zhang, Shuo Liang, Shuoguo Li, Gang Liu, Fanming Dai, Shegan Gao. miR-645 inhibits apoptosis of AGEJ. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1369. doi:10.1158/1538-7445.AM2014-1369