Long Noncoding RNA NEAT1 Promotes Tumorigenesis in H. Pylori Gastric Cancer By Sponging miR-30a To Regulate COX-2/BCL9 Pathway
Abstract Background: Helicobacter pylori (H. pylori) is a carcinogenic factor for gastric cancer. Our previous study demonstrated that H. pylori decreased the expression of microRNA(miRNA)-30a to promote the tumorigenesis in gastric cancer. However, the upstream regulatory mechanism of miR-30a hasn’t well-elucidated. In this study, we found the long non‑coding RNA (lncRNA) NEAT1 may sponge miR-30a to regulate COX-2/BCL9 pathway. Methods: The expression of NEAT1 was detected in gastric cancer tissues and tumour adjacent tissues by fluorescence in-situ hybridization(FISH) analysis and RT-qPCR. LncRNA-miRNA interaction networks were constructed using the RNAhybird and Starbase v.2.0. and then validated using dual-luciferase assay. The effects of NEAT1 dysregulation on the proliferative, migratory and invasive abilities of H. pylori filtrate infected gastric cancer cells were observed by cell counting kit-8 (CCK-8), colony formation, wound healing test and transwell assays. Western blot and RT-qPCR were performed to detect protein and RNA expression. The Immunohistochemistry(IHC) was carried out to analyze the location and expression of COX-2 and BCL9Results: FISH and RT-qPCR demonstrated that the expression of NEAT1 was up-regulated in gastric cancer tissues, especially in H. pylori gastric cancer tissues, and the expression of NEAT1 is negatively correlated with miR-30a(miR-30a-3p, miR-30a-5p). The proliferation, migration and invasion of H. pylori filtrate infected gastric cancer cells could be largely enhanced by the up-regulation of NEAT1, while the downregulation of NEAT1 decreased these abilities, and miR-30a could reverse the effect of NEAT1 on these abilities. Dual-luciferase assay identified that NEAT1 directly targeted miR-30a(miR-30a-3p, miR-30a-5p).Due to miR-30a(miR-30a-3p, miR-30a-5p) negatively regulated the expression of downstream COX-2 and BCL9, NEAT1 was identified to indirectly upregulate the expression of COX-2 and BCL9.IHC showed that the expression of COX-2 and BCL9 were increased in H. pylori gastric cancer tissues.Conclusion: The study demonstrated that lncRNA NEAT1 may act as a promoter oftumorigenesis in H. pylori gastric cancer, by sponging miR-30a(miR-30a-3p, miR-30a-5p) to regulate COX-2/BCL9 pathway.