Background: Recent studies have reported miR-145 dysregulated in colorectal cancer (CRC). In this study, miR-145 profiles were compared between CRC and corresponding non-tumour tissues.
Methods: The expression levels of miR-145 were analysed in CRC cell lines and tumour tissues by real-time PCR. A luciferase reporter assay confirmed direct targets. The functional effects of miR-145 were examined in transfected CRC cells in vitro and in vivo using established assays.
Results: Downregulation of miR-145 was detected in most primary CRC tumours, and was significantly correlated with a more aggressive phenotype of CRC in patients. In CRC cell lines, ectopic overexpression of miR-145 inhibited cell proliferation, motility and invasion in vitro. Stable overexpression of miR-145 suppressed tumour growth and pulmonary metastasis in vivo. Further studies indicated that miR-145 may directly interact with the 3'-untranslated region (3'-UTR) of Fascin-1 messenger RNA (mRNA), downregulating its mRNA and protein expression levels. In clinical specimens, Fascin-1 expression was negatively correlated with miR-145 expression.
Conclusions: MiR-145 has a critical role in the inhibition of invasive and metastatic capacities of CRC, probably through directly targeting Fascin-1. This miRNA may be involved in the development and progression of CRC.