MicroRNAs as regulators and mediators of c-MYC function.

In the past ten years microRNAs (miRNAs) have been widely implicated as components of tumor suppressive and oncogenic pathways. Also the proto-typic oncogene c-MYC has been connected to miRNAs. The c-MYC gene is activated in approximately half of all tumors, and its product, the c-MYC transcription factor, regulates numerous processes e.g. cell cycle progression, metabolism, epithelial-mesenchymal transition (EMT), metastasis, stemness, and angiogenesis, thereby facilitating tumor initiation and progression. c-MYC target-genes, which mediate these functions of c-MYC, represent a complex network of protein- and non-coding RNAs, including numerous miRNAs. For example, c-MYC directly regulates expression of the miR-17-92 cluster, miR-34a, miR-15a/16-1 and miR-9. Moreover, the expression and activity of c-MYC itself are under the control of miRNAs. Here, we survey how these networks mediate and regulate c-MYC functions. In the future, miRNAs connected to c-MYC may be used for diagnostic and therapeutic approaches. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology.