Transforming growth factor (TGF)-β1 is a significant stimulator of tumor invasion and metastasis. More recently, it has been found that TGF-β1 acts through microRNAs to regulate their target genes to promote cancer progresses. However, such similar regulation is rarely reported in colorectal cancer (CRC). Here, we observed a decrease in TGF-β1 expression in CRC specimens, compared with matched adjacent normal tissues. In parallel, there was an increase in miR-130b characterized in the same samples by microarray assay. Further, treatment of CRC cells with TGF-β1 caused a significant decrease in the expression of miR-130b and an increased CRC cell migration. Luciferase reporter assay revealed that miR-130b directly targeted the 3' untranslated region (3'UTR) region of integrin α5 gene, which encodes a key molecule involved in cell motility. Subsequently, in the overexpression of miR-130b CRC cells, we observed a decreased level of integrin α5 protein. The regulation of integrin α5 by miR-130b was further shown using the miR-130b mimics and inhibitor of miR-130b. And, knockdown miR-130b with inhibitor in the overexpression of miR-130b CRC cells recovered integrin α5 expression and integrin α5-mediated cell motility. Moreover, the inverse relevance between miR-130b and integrin α5 was also observed in CRC specimens. At last, the enhancement of integrin α5 in TGF-β1-treated cells can be reversed partly when rescuing miR-130b expression. Together, our findings suggested that TGF-β1 acted through miR-130b to promote integrin α5 expression, resulting in the enhanced migration of CRC cells.
Keywords: Cell motility; Integrin; TGF-β1; miR-130b.