EPOX inhibits angiogenesis by degradation of Mcl-1 through ERK inactivation
Journal
Clinical Cancer Research
Journal Volume
15
Journal Issue
15
Pages
4904-4914
Date Issued
2009
Author(s)
CHE-MING TENG
Abstract
Purpose: Antiangiogenic therapy is considered as an effective strategy for controlling the growth and metastasis of tumors. Among a myriad of biological activities described for xanthone derivatives, the anticancer activity is quite remarkable, but the molecular mechanism is not clearly resolved. In the present study, we investigated the antiangiogenic mechanism of 3,6-di(2,3-epoxypropoxy) xanthone (EPOX), a novel Mcl-1 targeting drug. Experimental Design: To evaluate the antiangiogenic activity of EPOX, we did cell viability, cell cycle, tube formation assay in vitro, and Matrigel plug assay in vivo. To evaluate the effect of EPOX on the endothelial signaling pathway, we did immunoblotting, immunoprecipitation, and immunofluorescence analysis. Intracellular glutathione levels were determined with the use of monochlorobimane, a glutathione-specific probe. Results: EPOX induced endothelial cell apoptosis in association with proteasomedependent Mcl-1 degradation. Down-regulation of Mcl-1 resulted in an increase in Mcl-1-free Bim, activation of Bax, and then signaling of mitochondria-mediated apoptosis. Additionally, glutathione depletion and extracellular signal-regulated kinase (ERK) inactivation was observed in EPOX-treated cells. Glutathione supplementation reversed the inhibitory effects of EPOX on ERK, which increases the phosphorylation ofMcl-1 at T163. Overexpression of mitogen-activated protein/ERK kinase (MEK) partially reversed the effect of EPOX on Mcl-1 dephosphorylation, ubiquitination, and degradation, further implicating ERK in the regulation of Mcl-1 stability. Conclusions: This study provides evidence that EPOX induces glutathione depletion, ERK inactivation, and Mcl-1 degradation on endothelial cells, which leads to inhibition of angiogenesis. Our results suggest that EPOX is a novel antiangiogenic agent, making it a promising lead compound for further development in the treatment of angiogenesisrelated pathologies. ? 2009 American Association for Cancer Research.
SDGs
Other Subjects
3,6 bis(2,3 epoxypropoxy)xanthone; BIM protein; glutathione; mitogen activated protein kinase; mitogen activated protein kinase kinase; protein Bax; protein mcl 1; unclassified drug; xanthone derivative; animal experiment; animal model; antiangiogenic activity; article; cell cycle; cell viability; controlled study; dephosphorylation; drug antagonism; drug effect; drug mechanism; enzyme inactivation; human; human cell; immunoblotting; immunofluorescence; immunoprecipitation; male; mouse; nonhuman; priority journal; protein degradation; ubiquitination; Angiogenesis Inhibitors; Animals; Apoptosis; Apoptosis Regulatory Proteins; Cell Survival; Cells, Cultured; Endothelial Cells; Endothelium, Vascular; Epoxy Compounds; Extracellular Signal-Regulated MAP Kinases; Glutathione; Humans; Mice; Mice, Nude; Mitochondria; Neovascularization, Pathologic; Proto-Oncogene Proteins c-bcl-2; Umbilical Veins; Xanthones; Xenograft Model Antitumor Assays
Type
journal article