Inhibition of Tumor Angiogenesis by Targeting Endothelial Surface ATP Synthase with Sangivamycin

Abstract

Sangivamycin, an antibiotic with anti-tumor and anti-herpes virus activities by inhibiting both DNA/RNA synthesis and protein kinase C activity, was reported to suppress selectively DNA synthesis and growth of human umbilical vein endothelial cells and their tube formation in vitro. Here, to address the potential clinical use of sangivamycin in future, we investigated its anti-angiogenic effect in in vivo chicken chorioallantoic membrane (CAM) and mouse dorsal air sac (DAS) assays, and investigated underlying mechanism. The effect of sangivamycin on blood vessel formation in CAM was observed under the microscope after treating for two days. For DAS assays, chambers fulfilled with tumor cells were implanted beneath mouse dorsal skin. After the mice were administered with sangivamycin, tumor-induced angiogenesis was observed under the microscope. The effect of sangivamycin on ATP synthesis on the endothelial cell surface was assayed by measuring ATP production with bioluminescence assay. Sangivamycin suppressed angiogenesis within CAM down to 94-71%, which was partially blocked by simultaneous addition of a 40-fold excess of adenosine. Sangivamycin also inhibited tumor-angiogenesis in the DAS assay by 61%, and suppressed ATP production on the endothelial cell surface by 75%. Sangivamycin inhibits the in vivo angiogenesis within CAM and tumor-induced angiogenesis within mouse dorsal skin, at least in part via inhibiting endothelial cell surface ATP metabolism in addition to inhibition of DNA/RNA synthesis and/or protein kinase C activity, suggesting a potential clinical use of sangivamycin as a novel anti-cancer reagent capable of targeting not only cancer cells but also endothelial cells.