Objective: To investigate the expression of miR-642 in gastric cancer and its mechanism in the proliferation and migration.

Methods: qRT-PCR was used to detect the expression of miR-642 in gastric cancer. Dual luciferase gene reporting system was used to verify the direct regulatory effect of miR-642 on KRT19 3' UTR. The mRNA and protein levels of KRT19 gene after transfection were detected by qRT-PCR and Western blot. The proliferation of miR-642 was detected by IncucyteS long term dynamic cell observation. Kaplan-Meier method was used to analyze the relationship between miR-642 expression level and prognosis in patients with gastric cancer.

Results: The expression of miR-642 in gastric cancer tissues was lower than that in paracancer tissues. The fluorescence intensity of MGC803 cells was significantly decreased after co-transfection of miR-642 mimics and wild-type KRT19-3 'UTR recombinant vector. The expression levels of KRT19 mRNA and protein were significantly decreased after transfected with miR-642 mimics and KRT19 siRNA. Western blot analysis of PTEN, Akt and mTOR proteins showed different expression. Prognostic survival analysis showed that gastric cancer patients with low expression of miR-642 had shorter survival.

Conclusion: miR-642 expression can negatively regulate the target gene KRT19.