Abstract 2520: FGFR2 and miR-671-5p as key participants involved in the progression of human esophageal squamous cell carcinoma

Esophageal cancer is the world9s tenth common malignant tumor. Esophageal cancer is divided into esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (ECA). ESCC is the dominant histological subtype. The overall 5-year survival rate for people with advanced-stage of ESCC is only about 10%-20%, but ESCC is still not well-studied. Therefore, it is very important to study the mechanism of cancer progression in ESCC in order to develop new therapies for this deadly disease. Fibroblast growth factor receptor2 (FGFR2) is one of the RTK members and generally regarded as an oncogene, but little is known about its function in ESCC. In our study, we proved FGFR2 played the key role in ESCC progression. From In vitro studies, overexpression of FGFR2 promoted the ESCC cells9 migration, invasion, and proliferation, which was confirmed through knocking down FGFR2 in ESCC cells. In vivo xenograft tumor mouse model studies showed the tumor size from ESCC cells with FGFR2 over-expression larger than that of the control group. Conversely, the tumor size from ESCC cells with FGFR2 knock-down was significantly smaller compared with the control group. Molecular mechanism studies showed that overexpression of FGFR2 activated the ERK and AKT signal pathways and altered the cell cycle in ESCC. In addition, decreased expression of miR-671-5p was identified by microRNA array and QPCR verify assay in ESCC–FGFR2 + tissue. Using a dual influence report system, we confirmed miR-671-5p could regulate expression of FGFR2. It was also found that FGFR2 was highly expressed whereas miR-671-5p was expressed at a low level in most of the FGFR2-positive ESCC clinic samples. Furthermore, we demonstrated that miR-671-5p could inhibit the proliferation and metastasis of ESCC cells in vitro and it could suppress growth of ESCC in vivo. The miR-671-5p suppressed MAPK and PI3K signal pathways through down-regulation of phosphorylation of FGFR2. Therefore, miR-671-5p was seen as a tumor suppressor in ESCC. Our results demonstrated that FGFR2 and miR-671-5p are potential therapeutic targets in ESCC. They both participate in the progression of ESCC, but also play the contrasting roles. Antagonists of FGFR2 or activators of miR-671-5p could be therapeutics against ESCC. Citation Format: Xiaojia Chen, Xiaoyan Li, Baoqing Tian, Xuan Tan, Wei Han, Jiakang Wang, An Hong. FGFR2 and miR-671-5p as key participants involved in the progression of human esophageal squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2520.