Hsa-miR-875-5p Inhibits Invasion And Migration By Targeting USF2 In Gastric Cancer

Background and Purpose:Worldwide,gastric cancer is one of the most common malignant tumors of digestive tract,with the fifth highest incidence and the fourth highest mortality.The proliferation and metastasis of gastric cancer is a multi-gene and multi-stage sequential cascade process.So far,there are few studies on the molecular mechanism of gastric cancer progression.Therefore,a better understanding of the molecular mechanisms involved in tumor formation and development will facilitate the development of novel therapeutic strategies and targets to treat gastric cancer.MiRNAs are involved in a series of important biological activities,such as early embryonic development,cell proliferation,apoptosis and differentiation.Cell proliferation and apoptosis usually undergo abnormal changes in tumors,so it is speculated that loss,mutation or overexpression of miRNA is related to the formation of malignant tumors,and miRNA may be an important biomarker for tumor diagnosis and therapeutic target.MiR-875-5p is abnormally expressed in a number of diseases,including colorectal cancer,liver cancer,thyroid cancer,prostate cancer,esophageal cancer and lung cancer.These results suggest that miR-875-5p plays a role in the occurrence and development of tumors.In previous studies,we found that the expression of miR-875-5p was reduced in gastric cancer,but its role in gastric cancer remains unclear.This study aims to explore the role of miR-875-5p in gastric cancer and its possible mechanism,hoping to provide a new target for the diagnosis and treatment of gastric cancer.Methods:QRT-PCR was used to detect the expression of miR-875-5p in gastric cancer tissues,adjacent tissues,human gastric cancer cell lines(AGS、BGC-823、HGC-27、MGC-803、SGC-7901 and MKN-45)and human gastric mucosal epithelial cell line GES-1.Then miR-875-5p mimics or inhibitor were transfected into gastric cancer cells to enhance or decrease the expression of miR-875-5p,and the transfection effect was detected by qRT-PCR assay.The effects of miR-875-5p on the proliferation,migration and invasion of AGS and MKN-45 gastric cancer cells were detected by CCK-8 assay,EdU assay,scratch assay and Transwell migration and invasion assay.Bioinformatics methods were used to predict the target genes of miR-875-5p.USF2 was identified as the target gene of miR-875-5p by dual luciferase reporter assays.Based on the inhibition of miR-875-5p in AGS and MKN-45 gastric cancer cells,the expression of si-USF2 was knocked down and a rescue experiment was conducted.CCK8 assay,EdU assay,scratch assay and Transwell migration and invasion assay were used to detect the changes in the biological characteristics of proliferation,migration and invasion of AGS and MKN-45 gastric cancer cells.The protein changes of TGF-β pathway and USF2 were detected by Western blot to further verify the targeted regulation of miR-875-5p on USF2.Finally,the effect of miR-875-5p on tumor proliferation in vivo was evaluated through the subcutaneous tumor experimental model in nude mice.Results:1.miR-875-5p is downregulated in gastric cancer tissues and cells.Overexpression of miR-875-5p can inhibit the proliferation,migration and invasion of gastric cancer cells,and promote the function after knockdown.2.USF2 is the target gene of miR-875-5p.3.USF2 knockdown partially offsets the promoting effect of miR-875-5p knockdown on proliferation,migration and invasion of gastric cancer cells.4.miR-875-5p knockdown promoted the activation of TGF-β signaling pathway,which was partially offset by USF2 knockdown.5.miR-875-5p inhibits growth of gastric cancer cells in nude mice.Conclusion:MiR-875-5p is low expressed in gastric cancer.As a tumor suppressor miRNA,miR-875-5p inhibits the proliferation,migration and invasion of gastric cancer and suppresses TGF-β signaling pathway by targeting USF2 in gastric cancer.