Alterations in the intracellular Ca2+ concentration and vimentin in endothelial cells following tumor cell‐endothelial cell interactions

Abstract

Intracellular calcium regulation and cytoskeletal proteins in both tumor cells and ECs provide important signaling mechanisms for tumor growth and metastasis. We investigated the influence of tumor cell‐EC interactions on the intracellular calcium ion concentration ([Ca2+]i) and vimentin expression and structural organization in ECs before and after the addition of PC‐3M prostate carcinoma cells. Acrylamide (a known disruptor of intermediate filaments), heparin and nifidipine (calcium channel blocker) was used. PC‐3M cells induced a rapid [Ca2+]i elevation and lead to altered vimentin distribution in ECs at the sites of tumor cell‐EC contact. Tumor cell‐induced [Ca2+]i elevation was significantly inhibited by heparin and nifidipine. Acrylamide‐induced collapse of vimentin filaments shifted the distribution of calcium ions from the cytoplasm to the nucleus and perinuclear field in ECs. Rapid [Ca2+]i elevation and alterations in vimentin distribution occur in ECs at the sites of tumor cell‐EC contact; the structural integrity of vimentin is partly related to the intracellular calcium ion distribution and concentration.