Regulation of mesenchymal phenotype by MicroRNAs in cancer.

Epithelial-mesenchymal transition (EMT) is a developmental process that converts epithelial cells into migratory and invasive cells. This process also plays an important role in cancer progression and metastasis by enabling tumor cells to leave primary sites. EMT is regulated by complex transcription networks and post-transcriptional modulators. MicroRNAs are single-stranded non-coding RNAs that represent a novel class of gene regulators. It has been shown that microRNAs are critical regulators of EMT process. The molecular mechanisms of EMT modulation by microRNAs include the suppression of transcription factors that directly regulate EMT and the down-regulation of cellular genes and pathways that are indirectly involved in EMT process. The expressions of microRNAs that control EMT process are dysregulated in cancer. In this review, we summarize the recent progress of microRNAs in EMT regulation.