Abstract LB-393: LINC01137 functions as a ceRNA promoting SMAD3 signaling and ESCC metastasis

Abstract

Abstract BACKGROUND: Esophageal squamous cell carcinoma (ESCC) is one of the leading cause of cancer-related death in China and some other parts of the world. Studies have shown that certain long non-coding RNAs (lncRNAs) are involved in cancer development and progression. In this study, we sought to identify lncRNAs that are associated with metastasis of ESCC and to explore their functions and therapeutic implications. METHODS: We performed RNA sequencing and analyzed the association of lncRNAs with ESCC survial time. The significantly associated lncRNAs that were overexpressed in ESCC were selected for further study. Knockdown or overexpression of interest lncRNAs were performed to investigate their effects on ESCC cell invasion and metastasis in vitro and in vivo in mice xengraft models. Biochemical assays such as RNAi, RNA immunoprecipitation, RNA pulldown and chromatin immunoprecipitation assays were used to examine the interactions among lncRNAs, mRNAs and microRNAs and between proteins and DNA. Patient survival time differentiated by RNA expression levels was estimated by Kaplan-Meier plotting and hazard ratios for death were calculated by Cox models. RESULTS: RNA sequencing identified 9 overexpressed lncRNAs were associated with ESCC survival. Among these lncRNAs, LINC01137 had the strongest effects on invasion and metastasis of ESCC cell lines in vitro and in vivo in mice. We found that ESCCwith high expression of LINC01137 had significantly more lymph node metastases compared with ESCC with low expression of LINC01137. Functional analyses demonstrated that LINC01137 may compete with HOXA1 mRNA for miR-608 binding. Higher expression level of LINC01137 in cells may prevent miR-608 from inhibiting HOXA1 translation. We found that HOXA1 is a transcription activator of SMAD2/3 and knockdown of LINC01137 substantilly reduced the SMAD3 signaling. Treatment of ESCC cells overexpressing LINC01137 with Halofuginone, a plant derivative that can inhibit SMAD3 phosphorylation, significantly reduced the abilities of migration and invasion. CONCLUSION: These results suggest that LINC01137 might function as a ceRNA competing with miR-608 for suppressing HOXA1 expression, which promotes SMAD3 signaling to enhance metastasis of ESCC cells. Citation Format: Mingming Shao, Jiahui Chu, Qionghua Cui, Linna Peng, Yingying Luo, Jiang Chang, Wen Tan, Chen Wu, Dongxin Lin. LINC01137 functions as a ceRNA promoting SMAD3 signaling and ESCC metastasis [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 LB-393.