miR-665 Suppresses the Epithelial-Mesenchymal Transition and Progression of Gastric Cancer by Targeting CRIM1

Background: Gastric cancer (GC) is one of the most common aggressive cancers and is characterized by high mortality. Increasing evidence has shown that microRNA-665 (miRNA-665) serves as inhibiting-miRNA in cancers. However, the role of miR-665 in GC is yet unclear. Methods: miR-665 was first analyzed using bioinformatics. Subsequent quantitative real-time PCR was used to detect miR-665 expression levels in different GC cell lines and tissues. The function of miR-665 in GC cells was determined via Cell Counting Kit 8, colony formation, wound healing, and transwell assays. Furthermore, Western blotting was utilized to measure the expression level of epithelial-mesenchymal transition (EMT)-related proteins. The target prediction and luciferase reporter assays were performed to confirm the binding between miR-665 and 3'-UTR of the CRIM1 gene. In addition, rescue assays were used to determine whether CRIM1 upregulation abolished the inhibitory effect of miR-665. Results: The expression of miR-665 was significantly decreased in GC patients and GC cell lines. Clinical and pathological analyses showed that the low expression of miR-665 was significantly associated with high TNM stage (P = 0.007), distant metastasis (P = 0.031), and poor differentiation (P = 0.029). Endogenic mimics of miR-665 remarkably suppressed GC cell proliferation, migration, invasion, and EMT in in vitro experiments. Inhibition of miR-665 expression induced the opposite effects. The results of the bioinformatics analysis and dual-luciferase assay showed that miR-665 targeted the 3'-UTR of the CRIM1 gene. Rescue assays revealed that overexpression of CRIM1 attenuated the inhibitory effects of miR-665 in GC progression and EMT. Conclusion: The overall study results demonstrated that miR-665 inhibits tumor progression and EMT in GC by targeting CRIM1, indicating that miR-665 might be a potential therapeutic target in the treatment of GC patients.