Circulating miRNAs as new activators of the JAK-STAT3 pathway

Cell communication is well known to rely on direct contacts or on secreted factors that bind to receptors located on the surface of their target cells. In addition to this classical pathway, recent results have shown that cells produce microvesicles that contain functional DNA, RNA and proteins that can be directly transferred to recipient cells. This induces proliferation, differentiation or cell death to the same extent as classical soluble factors. New data obtained from the laboratory of Napoleone Ferrara show that these microvesicles also contain miRNAs that can induce angiogenic activities in neighboring endothelial cells. When secreted from cancer cells, these miRNA-loaded vesicles penetrate recipient cells where they activate the JAK-STAT pathway. This represents a new type of intercellular signaling and a new way of activating the STAT transcription factors that could be of interest for the design of cancer treatments.