IDDF2019-ABS-0316 Long non-coding RNA CRCAL-2 promotes gastric cancer metastasis by activating wnt/beta-catenin pathway via stabilizing the nuclear transport protein RAN

Background Long non-coding RNAs (lncRNAs) are emerging as key molecules in gastric cancer(GC), yet their potential molecular mechanisms are not well understood. The aim of our study is to identify lncRNAs that are up-regulated in gastric cancer tissues and explore their function in gastric cancer metastasis. Methods RNA sequencing of 48 paired gastric tumor and non-tumor tissues in SYSUCC was conducted. The upregulated lncRNAs were selected and overlapped with those in TCGA database. A siRNA library was established using the top 50 lncRNAs highly expressed in GC and used to identify lncRNAs that significantly affected cell migration based on transwell assays. The expression of our focused lncRNA CRCAL-2(ColoRectal Cancer Associated LncRNA-2) was measured using quantitative reverse transcription PCR assays and lncRNA in situ hybridization. In vivo,cell-based and patient-derived xenograft (PDX) models were used to further explore roles of CRCAL-2 in GC metastasis. Then, RNA pull-down, mass spectrometry analyses, western blot and RNA-binding protein immunoprecipitation (RIP) were performed to identify interaction proteins and related mechanisms of CRCAL-2. Results LncRNA CRCAL-2, significantly overexpressed in the tumor tissues, was identified as the key regulator of GC metastasis. Upregulated CRCAL-2 in GC correlated with poor overall survival. Knockdown of CRCAL-2 significantly reduced GC cells migration, invasion, and metastasis of xenograft tumors in nude mice. Mechanistically, CRCAL-2 promoted GC metastasis by directly interacting with and stabilizing the nuclear transport protein RAN, resulting in increasement of nuclear import of beta-catenin and ultimately, activation of downstream targeted EMT(Epithelial-Mesenchymal Transition) genes. Additionally, the transcription factor YY1 could bind to the promoter of CRCAL-2 to upregulate its expression. Conclusions Our results suggest that YY1/CRCAL2/beta-catenin axis play a crucial role in GC metastasis, and the newly identified lncRNA CRCAL-2 might be developed as a biomarker and potential therapeutic target of GC in patients.