PTEN was discovered as a membrane-associated tumor suppressor protein nearly two decades ago, but the concept that it can be secreted and taken up by recipient cells is revolutionary. Since then, various laboratories have reported that PTEN is indeed secreted and available for uptake by other cells in at least two different guises. First, PTEN may be packaged and exported within extracellular vesicles (EV) called exosomes. Second, PTEN may also be secreted as a naked protein in a longer isoform called PTEN-long. While the conditions favouring the secretion of PTEN-long remain unknown, PTEN secretion in exosomes is enhanced by the Ndfip1/Nedd4 ubiquitination system. In this report, the authors describe conditions for packaging PTEN in exosomes and their potential use for mediating non cell-autonomous functions in recipient cells. they suggest that this mode of PTEN transfer may potentially provide beneficial PTEN for tumor suppression, however it may also propagate deleterious versions of mutated PTEN causing tumorigenesis.
PTEN can be secreted and taken up by recipient cells via exosomes
Putz U, Mah S, Goh CP, Low LH, Howitt J, Tan SS2. (2015) PTEN secretion in exosomes. Methods [Epub ahead of print]. [abstract]