The emerging role of miR-200 family of microRNAs in epithelial-mesenchymal transition and cancer metastasis.

MicroRNAs (miRNAs) play essential roles in many physiological and pathological processes, including tumor development, by regulating the expression of a plethora of mRNAs. Although the importance of miRNAs in tumorigenesis is well established, only recently have reports elucidated miRNAs as promoters or suppressors of metastasis. The miR-200 family has been shown to inhibit the initiating step of metastasis, epithelial-mesenchymal transition (EMT), by maintaining the epithelial phenotype through direct targeting of transcriptional repressors of E-cadherin, ZEB1 and ZEB2. These findings shed light into a miRNA-mediated regulatory pathway that influences EMT in a developmentally and pathologically relevant setting.