Malignant pleural mesothelioma (MPM) is an aggressive and fatal cancer of the pleural surface with poor prognosis and no targeted treatments. MPM is in urgent clinical need for better biomarkers to aid early diagnosis, improve prognostication and treatment options. Extracellular vesicles (EV) are currently the subject of extensive research in several cancers for their potential role as tumour biomarkers, however there are limited studies so far on their role in MPM. In particular, there are no studies to date concerning microvesicles and oncosomes in this disease. We aimed to characterize different classes of EV derived from five different MPM cells and patient plasma samples.
EV (oncosomes, microvesicles and exosomes) were isolated using classical centrifugation and ultracentrifugation from five MPM cell lines (NCI-H28, VMC23, MSTO-211H, NCI-H226, MM05) and the immortalized mesothelial cell line MeT-5A. Mesothelioma patient plasma samples (n=9) were processed similarly to yield EV. Nanoparticle tracking analysis (NTA) was undertaken to determine numbers and size distribution of EV. Isolated EV were analysed using flow cytometry (FC) after staining with annexin V-FITC. Western blotting (WB) was performed to verify the presence of EV markers and MPM tumour biomarkers.
NTA and FC results demonstrated major differences in the total number of oncosomes, microvesicles and exosomes released between different MPM cell lines as well as patient samples versus controls. WB revealed the presence of important diagnostic and prognostic biomarkers in different classes of EV. We show that different classes of EV have the potential to serve as novel biomarkers in MPM.