Platelet-Derived Extracellular Vesicles Stimulate Migration through Partial Remodelling of the Ca 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 handling machinery, which drives MDA-MB-231 cell motility.

Methods: PEVs were isolated from human blood platelets, and Fura-2/AM Ca imaging, RT-qPCR, and immunoblotting were exploited to assess their effect on intracellular Ca dynamics and Ca-dependent migratory processes in MDA-MB-231 cells.

Results: Pretreating MDA-MB-231 cells with PEVs for 24 h caused an increase in Ca release from the endoplasmic reticulum (ER) due to the up-regulation of SERCA2B and InsPR1/InsPR2 mRNAs and proteins. The consequent enhancement of ER Ca depletion led to a significant increase in store-operated Ca entry. The larger Ca 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 handling machinery.