Malignant pleural mesothelioma (MPM) is an aggressive, asbestos-related tumor of the pleural surface with a prolonged latency period (10 to 40 years) and poor prognosis. MPM is in urgent clinical need for better biomarkers to aid early diagnosis, prognostication and improved treatment options. An important area of research in MPM is understanding intercellular communication carried out by extracellular vesicles (EV). While a number of studies have investigated exosome release by MPM cells, little is known about the role of microvesicles and oncosomes in this disease. In this pilot study, we aimed to characterize different classes of EV derived from MPM cells.
EV (oncosomes, microvesicles and exosomes) were isolated using classical centrifugation and ultracentrifugation from the MPM cell line NCI-H28 and the immortalized mesothelial cell line MeT-5A. Nanoparticle tracking analysis (NTA) was performed to determine numbers and size distribution of EV. Isolated EV were analysed using flow cytometry after staining with annexin V-FITC.
NTA results demonstrated major differences in the total number of oncosomes, microvesicles and exosomes released from the two cell lines. Flow cytometry confirmed an increase in the number of oncosomes and microvesicles in H28 compared to MeT-5A. Our results warrant further investigation into the mechanisms involved in the formation and release of different classes of EV, and in the cargo the EV carry in MPM cells.
In conclusion, we show that MPM cells secrete different classes of EV that are potentially involved in intercellular communication and have the potential to serve as novel biomarkers in MPM.