CHM-1, a New Vascular Targeting Agent, Induces Apoptosis of Human Umbilical Vein Endothelial Cells via p53-mediated Death Receptor 5 Up-regulation

Abstract

CHM-1 (2'-fluoro-6,7-methylenedioxy-2-phenyl-4-quinolone) has been identified as a potent antitumor agent in human hepatocellular carcinoma; however, its role in tumor angiogenesis is unclear. This study investigated the effects of CHM-1 and the mechanisms by which it exerts its antiangiogenic and vascular disrupting properties. Using a xenograft model antitumor assay, we found that CHM-1 significantly inhibits tumor growth and microvessel formation. Flow cytometry, immunofluorescence microscopy, and cell death enzyme-linked immunosorbent assay kit revealed that CHM-1 inhibits growth of human umbilical vein endothelial cells (HUVEC) by induction of apoptotic cell death in a concentration-dependent manner. CHM-1 also suppresses HUVEC migration and capillary-like tube formation. We were able to correlate CHM-1-induced apoptosis in HUVEC with the cleavage of procaspase-3, -7, and -8, as well as with the cleavage of poly(ADP-ribose) polymerase by Western blotting assay. Such sensitization was achieved through up-regulation of death receptor 5 (DR5) but not DR4 or Fas. CHM-1 was also capable of increasing the expression level of p53, and most importantly, the induction of DR5 by CHM-1 was abolished by p53 small interfering RNA. Taken together, the results of this study indicate that CHM-1 exhibits vascular targeting activity associated with the induction of DR5-mediated endothelial cell apoptosis through p53 up-regulation, which suggests its potential as an antivascular and antitumor therapeutic agent.