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.