Role of miRNA clusters in epithelial to mesenchymal transition in cancer.

Epithelial to mesenchymal transition (EMT) is a multistep biological process in which epithelial cells acquire characteristics of mesenchymal cells. Inappropriate activation of EMT contributes to the acquisition of pro-metastatic characteristics and cancer progression. EMT process involves the downregulation of epithelial markers (EpCAM, CDH1) and upregulation of mesenchymal markers (VIM, CDH2) and EMT-transcription factors (ZEB1/2, TWIST1/2, SNAI1, SLUG). MicroRNAs, a class of non-coding RNA post-transcriptionally govern gene expression by binding to the target mRNAs. A large proportion of miRNAs occur as miRNA clusters consisting of two or more miRNA coding genes. MiRNA clusters are reported to regulate diverse biological functions, including EMT. This comprehensive review discusses the role of miRNA clusters in EMT.