MicroRNAs (miRNAs) and their target genes have been shown to play an important role in gastric cancer but have not been fully clarified. Therefore, our goal was to identify the key miRNA-mRNA regulatory network in gastric cancer by utilizing a variety of bioinformatics analyses and experiments. A total of 242 miRNAs and 1080 genes were screened from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO), respectively. Then, survival-related differentially expressed miRNAs and their differentially expressed target genes were screened. Twenty hub genes were identified from their protein-protein interaction network. After weighted gene co-expression network analysis was conducted, we selected miR-137-3p and its target gene, COL5A1, for further research. We found that miR-137-3p was significantly downregulated and that overexpression of miR-137-3p suppressed the proliferation, invasion, and migration of gastric cancer cells. Furthermore, we found that its target gene, COL5A1, could regulate the expression of another hub gene, FSTL1, by sponging miR-137-3p, which was confirmed by dual-luciferase reporter assays. Knockdown of COL5A1 inhibited the proliferation, invasion, and migration of gastric cancer cells, which could be rescued by the miR-137-3p inhibitor or overexpression of FSTL1. Ultimately, bioinformatics analyses showed that the expression of FSTL1 was highly correlated with immune infiltration.
Keywords: COL5A1; FSTL1; bioinformatics; gastric cancer; immune infiltration; miR-137-3p.