Platelet-Derived Extracellular Vesicles Stimulate Migration through Partial Remodelling of the Ca(2+) Handling Machinery in MDA-MB-231 Breast Cancer Cells

Background: Platelets can support cancer progression via the release of microparticles and microvesicles that enhance the migratory behaviour of recipient cancer cells. We recently showed that platelet-derived extracellular vesicles (PEVs) stimulate migration and invasiveness in highly metastatic MDA-MB-231 cells by stimulating the phosphorylation of p38 MAPK and the myosin light chain 2 (MLC2). Herein, we assessed whether the pro-migratory effect of PEVs involves the remodelling of the Ca(2+) handling machinery, which drives MDA-MB-231 cell motility. Methods: PEVs were isolated from human blood platelets, and Fura-2/AM Ca(2+) imaging, RT-qPCR, and immunoblotting were exploited to assess their effect on intracellular Ca(2+) dynamics and Ca(2+)-dependent migratory processes in MDA-MB-231 cells. Results: Pretreating MDA-MB-231 cells with PEVs for 24 h caused an increase in Ca(2+) release from the endoplasmic reticulum (ER) due to the up-regulation of SERCA2B and InsP(3)R1/InsP(3)R2 mRNAs and proteins. The consequent enhancement of ER Ca(2+) depletion led to a significant increase in store-operated Ca(2+) entry. The larger Ca(2+) mobilization from the ER was required to potentiate serum-induced migration by recruiting p38 MAPK and MLC2. Conclusions: PEVs stimulate migration in the highly metastatic MDA-MB-231 breast cancer cell line by inducing a partial remodelling of the Ca(2+) handling machinery.