Intracellular Ca signaling in endothelial cells by the angiogenesis inhibitors endostatin and angiostatin

Jiang, Lianwei, Vivekanand Jha, Mohanraj Dhanabal, Vikas P. Sukhatme, and Seth L. Alper. Intracellular Ca21 signaling in endothelial cells by the angiogenesis inhibitors endostatin and angiostatin. Am J Physiol Cell Physiol 280: C1140–C1150, 2001.—Intracellular signaling mechanisms by the angiogenesis inhibitors endostatin and angiostatin remain poorly understood. We have found that endostatin (2 mg/ml) and angiostatin (5 mg/ml) elicited transient, approximately threefold increases in intracellular Ca21 concentration ([Ca]i). Acute exposure to angiostatin or endostatin nearly abolished subsequent endothelial [Ca]i responses to carbachol or to thapsigargin; conversely, thapsigargin attenuated the Ca21 signal elicited by endostatin. The phospholipase C inhibitor U-73122 and the inositol trisphosphate (IP3) receptor inhibitor xestospongin C both inhibited endostatin-induced elevation in [Ca]i, and endostatin rapidly elevated endothelial cell IP3 levels. Pertussis toxin and SB-220025 modestly inhibited the endostatin-induced Ca21 signal. Removal of extracellular Ca21 inhibited the endostatin-induced rise in [Ca]i, as did a subset of Ca21-entry inhibitors. Peak Ca21 responses to endostatin and angiostatin in endothelial cells exceeded those in epithelial cells and were minimal in NIH/3T3 cells. Overnight pretreatment of endothelial cells with endostatin reduced the subsequent acute elevation in [Ca]i in response to vascular endothelial growth factor or to fibroblast growth factor by ;70%. Intracellular Ca21 signaling may initiate or mediate some of the cellular actions of endostatin and angiostatin.