Objective: To examine the role of miR-145 in the myofibroblastic transdifferentiation of oral fibroblasts.
Methods: Human primary oral fibroblasts were transiently transfected with premiR-145, or a control non-targeting miRNA, and subsequently treated with 5ng/ml TGF-β1 for 48h. Markers of myofibroblast transdifferentiation such as alpha smooth muscle actin (αSMA), MMP2 and versican were analysed using immunoblotting and qRT-PCR. Collagen I gels were used to analyse fibroblast contractility, and transwell assays to assess effects of fibroblasts on chemotaxis of cancer cells.
Results: qRT-PCR and immunoblotting revealed an increase in αSMA and MMP-2 expression in fibroblasts treated with TGF-β1. In addition, elevated levels of versican isoforms V0 and V1 were detected on TGF-β1 treatment. Fibroblasts overexpressing miR-145 showed a significant reduction in versican and αSMA expression and contractility. This suggested that miR-145 is able to inhibit the acquisition of the myofibroblast phenotype in response to TGF-β1. This was reflected in a reduced ability of conditioned media from TGF-β1-treated miR-145 over-expressing fibroblasts to promote chemotaxis of oral cancer cells.
Conclusions: Our data suggests that miR145 is able to block oral myofibroblast transdifferentiation, a key pro-tumourigenic mechanism in the tumour microenvironment. Exogenous delivery of miR-145 may therefore represent a potential therapeutic opportunity.