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 p21 CIP͞WAF , a cyclin-dependent kinase inhibitor, in endothelial cells but not in embryonic or adult fibroblasts. Moreover, primary endothelial cells isolated from p53 ؊͞؊ and p21 CIP͞WAF؊͞؊ mice are resistant to the cytostatic activity of TNP-470. We also demonstrate that p21 CIP͞WAF؊͞؊ 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 p21 CIP͞WAF expression and subsequent growth arrest.

A methionine aminopeptidase-2 inhibitor, PPI-2458, for the treatment of rheumatoid arthritis

“…Their GI 50 s are similar to the concentration of PPI-2458 required to achieve 50% MetAP-2 enzyme inhibition in both cell types. Similar data have previously been reported for HUVEC exposed to TNP-470 (15,20,23). The MetAP-2 inhibition curve in PPI-2458-resistant NHDF-Ad closely resembles that of HFLS-RA and HUVEC, indicating that MetAP-2 enzyme inhibition is achieved equally in these three cell types.…”

“…Fumagillin class compounds, such as TNP-470, have previously been shown to have potent antiproliferative activity on endothelial cells in vitro (15,20,23,24). Our data are in full agreement with these reports, in that PPI-2458 potently inhibited HUVEC proliferation with a GI 50 of 0.2 nM and a maximum inhibition of Ͼ95% at 1 nM (Fig.…”

“…The selective inhibition of the MetAP-2 enzyme is believed to be the underlying molecular mechanism for the potent antiangiogenic activity of this class of compounds. In stark contrast to endothelial cells, however, the proliferation of a wide range of primary human cell types is not affected by the fumagillin class of molecules (23). Here we report that PPI-2458, a structural analog of fumagillin, potently and selectively inhibits the proliferation of HFLS-RA (GI 50 0.04 nM), one of only a few primary cell types identified to date that are exquisitely sensitive to growth inhibition caused by this class of molecules.…”

“…Terminally differentiated cardiocytes depend on high p21 CIP/WAF levels to maintain cell cycle arrest, which in turn are required to down-regulate PCNA (32). Furthermore, elevated p21 CIP/WAF protein levels are detected in HUVEC after TNP-470-induced G 1 arrest, thus suggesting a link between MetAP-2 inhibition and two key cell cycle regulators, PCNA and p21 CIP/WAF (23,33). It remains to be determined what that link is in molecular terms.…”

“…Paw swelling was monitored by using a plethysmometer (Stoelting) according to instrument specifications. The volumes of the two hind paws were measured and averaged on days 1, 4, 5,6,8,11,13,15,17,19,21,23,25,27,29, and 31. Eight animals were assigned to each group, except the vehicle control (n ϭ 4).…”