LncRNA ASAP1-IT1 Enhances Cancer Cell Stemness via Regulating miR-509-3p/YAP1 Axis in NSCLC

Abstract

\n Background: Non-small cell lung cancer (NSCLC) is a major cause of cancer-related death worldwide, and cancer stem cell is mainly responsible for the poor clinical outcome of NSCLC. Although previous reports indicated long noncoding RNAs (lncRNAs) play important roles in cancer stemness maintain, the underlying causes mechanisms remain is still mysterious. Our study aims to investigate the role of ASAP1 Intronic Transcript 1 (ASAP1-IT1) in cancer cell stemness of NSCLC. Methods: qRT-PCR analysis the expression of ASAP1-IT1 and microRNA-509-3p (miR-509-3p) in NSCLC tissues, cancer cells and spheres of cancer cells-derived cancer stem cells. Knockdown of ASAP1-IT1 or overexpression of miR-509-3p in NSCLC cells by infection or transfection. Sphere formation and colony formation detects NSCLC stem cell-like properties and tumor growth in vitro. Luciferase reporter assays, RNA immunoprecitation (RIP) and qRT-PCR assays analyzed the interaction between lncRNA and miRNA, qRT-PCR and Western blot detect ASAP1-IT1/miR-509-3p axis s regulation on the expression of regulated genes. NSCLC xenograft mice model validates ASAP1-IT1 role in NSCLC stemness and tumor growth in vivo. Results: ASAP1-IT1 was up-regulated in NSCLC tissues, cancer cells, and in spheres of A549-derived cancer stem cells. Downregulated ASAP1-IT1 or miR-509-3p significantly decreased cell colony formation and stem cell-like properties of A549-dereived stem cells with decreased expression of stem cell biomarkers SOX2, CD34, and CD133, and suppressing the expression of cell growth-related genes, Cyclin A1, Cyclin B1, and PCNA. Furthermore, knockdown of ASAP1-IT1 or overexpression of miR-509-3p repressed tumor growth in nude mice via reducing expression of tumorigenic genes. ASAP1-IT1 was found to interact with miR-509-3p. Moreover, overexpression of ASAP1-IT1 blocked miR-509-3p mediated regulation of stem cell-like properties, cell growth, and cell apoptosis of A549-dereived stem cells both in vitro and in vivo. Finally, the level of YAP1 was regulated by ASAP1-IT1 and miR-509-3p.Conclusions: YAP1-involved ASAP1-IT1/miR-509-3p axis promoted NSCLC progression by regulating cancer cell stemness，and targeting related signaling is a promising therapeutic strategy to overcome NSCLC stemness.