Emerging role of miR-106b-25/miR-17-92 clusters in the control of transforming growth factor beta signaling.

Inactivation of the transforming growth factor beta (TGFbeta) tumor suppressor pathway is a main step in the development of a variety of human tumors. The miR-106b-25 and miR-17-92 clusters are emerging as key modulators of TGFbeta signaling in gastrointestinal and other tumors, interfering with cell cycle arrest and apoptosis when overexpressed in cancer cells. Genetic ablation of these microRNAs (miRNAs) reveals their physiologic role in the control of liver and central nervous system apoptosis, supporting the notion that miRNA-based homeostatic mechanisms can be usurped by cancer cells to resist TGFbeta tumor suppression.