Vesicular control of metastasis: entrap the “virtuous” and free the “wicked” microRNA

Metastasis, the process by which cancers disseminate to sites distant from the primary tumor, is a complex process orchestrated by genetic, epigenetic and microenvironmental factors (1). This process is initiated and sustained by an accelerated Darwinian-based selection of cellular clones capable of invading the extracellular matrix, penetrating veins and lymphatic vessels (intravasation), surviving a hostile circulation environment, extravasation, arresting at distant organs, and ultimately colonizing them (2).