Background: Gastric cancer (GC) is a common tumor found worldwide, and cisplatin is the first-line agent for the treatment of GC. However, the resistance to cisplatin is an obstacle. Here, we explored the biological mechanism of long noncoding RNA regulator of reprogramming (ROR) in the cisplatin resistance of GC. Materials and Methods: ROR, miR-519d-3p, and high mobility group protein A2 (HMGA2) expression in GC tissues and cells were measured by quantitative real-time polymerase chain reaction and Western blot. Cell viability, migration, invasion, and apoptosis were detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, transwell assay, and flow cytometry, respectively. The relative protein expression was detected by Western blot. The interactions between miR-519d-3p and ROR, HMGA2 were predicted using miRcode and starBase v2.0 online database, and then verified by dual luciferase reporter assay and RNA immunoprecipitation assay. In addition, the xenograft tumor mouse model was constructed to verify the biological role of ROR in vivo. Results: The levels of ROR, HMGA2 were significantly upregulated, and miR-519d-3p was apparently downregulated in GC tissues and cells. The miRcode and starBase v2.0 online websites and dual luciferase reporter assay validated that miR-519d-3p directly interacted with ROR and HMGA2. Furthermore, ROR knockdown downregulated HMGA2 to restrain cell proliferation, migration, invasion, epithelial-mesenchymal transition (EMT), and cisplatin resistance in GC cells by targeting miR-519d-3p. In addition, the depletion of ROR repressed the xenograft tumor growth in vivo. Conclusion: In conclusion, we first found the ROR/miR-519d-3p/HMGA2 regulatory network to regulate cell proliferation, migration, invasion, EMT, and cisplatin resistance in GC, and this may shed light on the GC tumorigenesis.
Keywords: HMGA2; cisplatin; gastric cancer; lncRNA ROR; miR-519d-3p.