Plant defensin PvD1 modulates the membrane composition of breast tumour-derived exosomes

This journal is © The Royal Society of Chemistry 2019 One of the most important causes of failure in tumour treatment is the development of resistance to therapy. Cancer cells can develop the ability to lose sensitivity to anti-neoplastic drugs during reciprocal crosstalk between cells and their interaction with the tumour microenvironment (TME). Cell-to-cell communication regulates a cascade of interdependent events essential for disease development and progression and can be mediated by several signalling pathways. Exosome-mediated communication is one of the pathways regulating these events. Tumour-derived exosomes (TDE) are believed to have the ability to modulate TMEs and participate in multidrug resistance mechanisms. In this work, we studied the effect of the natural defensin from common bean, PvD1, on the formation of exosomes by breast cancer MCF-7 cells, mainly the modulatory effect it has on the level of CD63 and CD9 tetraspanins. Moreover, we followed the interaction of PvD1 with biological and model membranes of selected composition, by biophysical and imaging techniques. Overall, the results show that PvD1 induces a dual effect on MCF-7 derived exosomes: the peptide attenuates the recruitment of CD63 and CD9 to exosomes intracellularly and binds to the mature exosomes in the extracellular environment. This work uncovers the exosomemediated anticancer action of PvD1, a potential nutraceutical agent. The authors thank Fundação para a Ciência e a Tecnologia (FCT I.P., Portugal) for funding – PTDC/BBB-BQB/1693/2014, and also acknowledge financial support from the Brazilian agencies CNPq, CAPES, and FAPERJ (E-26/203.090/2016; E-26/202.132/2015). Julia Skalska, Filipa D. Oliveira, Tiago N. Figueira and Diana Gaspar acknowledge FCT I.P. for fellowships PD/BD/114177/2016, PD/BD/135046/2017, SFRH/BD/5283/2013 and SFRH/BPD/109010/2015 respectively. Marie Skłodowska-Curie Research and Innovation Staff Exchange (RISE) is also acknowledged for funding: call H2020-MSCA-RISE-2014, Grant agreement 644167, 2015–2019.