The miRNAs and epithelial-mesenchymal transition in cancers.

The epithelial-mesenchymal transition (EMT) is a process by which epithelial tumor cells acquire migratory and invasive abilities that enable them to spread to other organs. During this process, the tight junction molecule, E-cadherin, is often downregulated through transcription repression by the EMT-inducing transcription factors (EMT-TFs). MicroRNAs (miRNAs) are a class of small noncoding RNA molecules which bind to the complementary sequences within mRNA molecules. They post-transcriptionally govern gene silencing, thus affecting a broad range of physiological conditions, including EMT. In this review, we will discuss some well-known as well as brand-new EMT-related miRNAs and the signaling pathways in the tumor milieu that regulate their expressions and control cancer invasion and metastasis. Finally, we will discuss the application of miRNAs as therapeutic targets for treatment of cancer.