The antiangiogenic agent TNP-470 requires p53 and p21 CIP/WAF for endothelial cell growth arrest

Abstract
Targeting the endothelial cell cycle as an antiangiogenic strategy has been difficult given the ubiquitous expression of critical cell cycle regulators. Here, we show that the antiangiogenic drug TNP-470 displays striking cell-type specificity insofar as it induces the expression of p21CIP/WAF, a cyclin-dependent kinase inhibitor, in endothelial cells but not in embryonic or adult fibroblasts. Moreover, primary endothelial cells isolated from p53−/− and p21CIP/WAF−/− mice are resistant to the cytostatic activity of TNP-470. We also demonstrate that p21CIP/WAF−/− mice are resistant to the antiangiogenic activity of TNP-470 in the basic fibroblast growth factor corneal micropocket angiogenesis assay. We conclude that TNP-470 induces p53 activation through a unique mechanism in endothelial cells leading to p21CIP/WAF expression and subsequent growth arrest.