Background: MiR-646 has been reported to be aberrantly expressed in human cancers. However, the underlying molecular mechanisms of action of miR-646 in gastric cancer (GC) have not yet been investigated.
Methods: In vitro function of miR-646 in GC was evaluated using EdU assay, plate colony formation assay, and matrigel invasion assay. Real-time PCR or western blotting was performed to detect miR-646 and FOXK1 expressions. In vivo tumour growth and metastasis were conducted in nude mice.
Results: MiR-646 expression was downregulated in GC tissues compared with adjacent normal tissues. Low miR-646 expression is associated with malignant progression. Transient transfection of GC cells with miR-646 inhibited their growth and migration. Moreover, miR-646 influenced the expression of epithelial-mesenchymal transition (EMT)-associated proteins. TGF-β1 treatment significantly suppressed the expression of miR-646 and overexpression of this microRNA counteracted the influence of the TGF-β1-induced EMT phenotype. In terms of the underlying mechanism, miR-646 directly targeted FOXK1. In vivo, it inhibited the FOXK1-mediated proliferation and EMT-induced metastasis. Consistently, inverse correlations were also observed between the expression of miR-646 and FOXK1 in human GC tissue samples. Furthermore, miR-646 regulated Akt/mTOR signalling after FOXK1.
Conclusions: miR-646 inhibited GC cell proliferation and the EMT progression in GC cells by targeting FOXK1.