The role of membrane vesicles in tumorigenesis.

Membrane vesicles are membrane-covered cell fragments generated by all cell types. They comprise a recently recognized new system of intercellular communication, believed to play a pivotal role in information transfer between cells, as they display a large number of biomolecules enclosed within the membrane as well as in the membrane proper. The phenotype of the donor cell is reflected in the vesicular protein content, which also allows the identification of the original cell. Membrane vesicles have been implicated in several physiological and pathological processes, most notably in tumorigenesis. Tumor-derived vesicles may serve as prognostic markers, they were detected in blood plasma and in other body fluids. Their size varies between 30 and 1000 nm. All of them reflect the special potential of tumor cells for survival and for the expansion of the tumor, independently from cell-to-cell contact. Tumor-derived vesicles have the potential to facilitate the escape of tumor cells from immune surveillance through their protein and RNA content, at the same time they are involved in the establishment of a beneficial environment for newly formed and migrating tumor cells, influencing angiogenesis and the reorganization of the extracellular matrix. Elucidating the properties of tumor-derived vesicles should increase our understanding in tumor biology and open new perspectives in cancer treatment. Tumor-derived vesicles are involved in tumorigenesis at multiple level and drugs themselves can be expulsed from tumor cells via vesicles. Consequently, interfering with the formation, release and propagation of these vesicles can be a novel and alternative issue in cancer therapy. The present review is an overview of the roles of membrane vesicles in tumorigenesis showing also the potential to consider them as new targets in tumor therapy.