MiR-30a acts as a tumor suppressor by double-targeting COX-2 and BCL9 in H. pylori gastric cancer models

Xuan Liu,Qing Ji,Hua Sui,Yanna Liu,Lihong Zhou,Chengcheng Zhang,Ningning Liu,Xiaowei Liu,Qi Li,Songpo Wang

doi:10.1038/s41598-017-07193-w

Abstract

Helicobacter pylori (H. pylori) is one of the most important factors that affect the development of gastric cancer, and its mechanism remains un-elucidated. Our present study found that, miR-30a is crucial for regulating the growth and migration of H. pylori infected gastric cancer in vitro by targeting COX-2 and BCL9. In details, double-stranded miR-30a precursor produced two single-stranded and matured miRNAs including miR-30a-3p and miR-30a-5p, which played significant biological functions in two different manners. First, miR-30a-3p inhibited COX-2 expression and regulated nuclear translocation of β-catenin, and second, miR-30a-5p targeted BCL9 to regulate TCF/LEF promoter activity followed by affecting β-catenin downstream target gene expression. In vivo, miR-30a knockout mice were successfully achieved using CRISPR/Cas9 gene editing technology. Compared with H. pylori-infected wild-type mice, H. pylori-infected miR-30a knockout mice showed increased incidence of chronic gastritis, chronic atrophic gastritis, atypical hyperplasia, and other precancerous lesions or adenocarcinoma manifestations in the antral or gastric mucosa of mice, as well as regulation of genes closely associated with tumor development. Taken together, miR-30a acts as a tumor suppressor by double-targeting COX-2 and BCL9, and significantly affects the development of H. pylori-induced gastric cancer, shedding new light on the mechanisms underlying H. pylori-associated gastric cancer.

Highlights

Helicobacter pylori (H. pylori) is an important pathogenic factor for gastric cancer[1,2,3,4], and the International Agency for Research on Cancer (IARC) and World Health Organization (WHO) have attributed H. pylori as the first class carcinogenic factor for gastric cancer[5, 6]
Based on the microrna.org, mirDB, Targetscan 7.1 and starBase v2.0 network databases, we obtained a library of human miRNAs that target regulation of the COX-2 gene
When the MKN45 cells were treated with the H. pylori and miR-30a-3p mimic simultaneously, the quantity of β-catenin protein in the nucleus significantly reduced, whereas the miR-30a-3p inhibitor had the opposite effect compared to the miR-30a-3p mimic (Fig. 3F). These results suggested that, miR-30a-3p could affect the biological function of H. pylori-infected gastric cancer cells by regulating COX-2 expression and nuclear translocation of β-catenin protein

Summary

Introduction

Helicobacter pylori (H. pylori) is an important pathogenic factor for gastric cancer[1,2,3,4], and the International Agency for Research on Cancer (IARC) and World Health Organization (WHO) have attributed H. pylori as the first class carcinogenic factor for gastric cancer[5, 6]. Previous studies have shown that H. pylori can activate p38MAPK signaling pathway and thereby increase the expression of the COX-2 gene[7,8,9]. Our primary purpose was to determine the miRNAs that regulate COX-2 expression in H. pylori-infected gastric cancer cells, and to further explore the key miRNAs that regulate COX-2, as well as downstream gene expression or signaling pathways involved. The detailed mechanism of miR-30a-5p targeting BCL9 to regulate the downstream gene expression or involved signaling pathways in H. pylori-infected gastric cancer is unclear. Another aim of the current study was to determine if miR-30a-5p targets BCL9 to regulate TCF/LEF promoter activity[16] and downstream gene expression of β-catenin. In this study, we showed the important roles of miR-30a in the development of H. pylori-induced gastric cancer

Methods

Results

Conclusion