Multidrug resistant tumour cells shed more microvesicle-like EVs and less exosomes than their drug-sensitive counterpart cells

Background: Multidrug resistance (MDR) is a serious impediment to cancer treatment, with overexpression of drug efflux pumps such as P-glycoprotein (P-gp) playing a significant role. In spite of being a major clinical challenge, to date there is no simple, minimally invasive and clinically validated method for diagnosis of the MDR phenotype using non-tumour biological samples. Recently, P-gp has been found in extracellular vesicles (EVs) shed by MDR cancer cells. This study aimed to compare the EVs shed by MDR cells and their drug sensitive cellular counterparts, in order to identify biomarkers of MDR. Methods: Two pairs of MDR and drug-sensitive counterpart tumour cell lines were studied as models. EVs were characterized in terms of size and molecular markers and their protein content was investigated by proteomic analysis and Western blot. Results: We found that MDR cells produced more microvesicle-like EVs and less exosomes than their drug sensitive counterpart. EVs from MDR cells contained P-gp and presented a different content of proteins known to be involved in the biogenesis of EVs, particularly in the biogenesis of exosomes. Conclusions: The determination of the size and of this particular protein content of EVs shed by tumour cells may allow the development of a minimally-invasive simple method of detecting and predicting MDR. General significance: This work describes for the first time that cancer multidrug resistant cells shed more microvesicle-like EVs and less exosomes than their drug-sensitive counterpart cells, carrying a specific content of proteins involved in EV biogenesis that could be further studied as biomarkers of MDR. (C) 2015 Elsevier B.V. All rights reserved.