Pharmaceutica Analytica Acta

Abstract

Anti-Angiogenic Effect of P2X7 Receptor Antagonist Oxidized ATP as a Mechanism of Anti-Tumor Growth

Shizuka Seki, Mitsutoshi Tsukimoto, Akina Suzuki, Fumie Hattori, Erina Takai, Yasuhiro Ohshima and Shuji Kojima

Extracellular ATP accumulated in tumor microenvironment activates P2X7 receptor on cellular membrane of cancer cells. Recently, an importance of P2X7 receptor in cancer growth or malignancy has been suggested. We have reported an inhibitory effect of oxidized ATP (oxATP), which is an irreversible antagonist of P2X7 receptor, on melanoma growth. However, the mechanism has not yet been established. In this study, we investigated the effect of oxATP on angiogenesis in vitro and in vivo to reveal the mechanism of anti-tumor growth by oxATP. We found that oxATP strongly suppressed cell migration and wound healing in mouse endothelium b.End3 cells, indicating the suppressive effect of oxATP on angiogenesis in vitro. We further investigate the effect of oxATP on angiogenesis in vivo. We performed ligation of the femoral artery and vein of BALB/c mouse, and a laser doppler perfusion image analyzer recorded blood flow postoperatively. The blood flow of hind limb was significantly decreased by the operation and recovered within 1-2 weeks, indicating angiogenesis. However, administration of oxATP to mice significantly suppressed the recovery of blood flow. Increase of serum matrix metalloproteinases (MMPs) and vascular endothelial growth factor (VEGF) levels contribute to angiogenesis. The serum MMP-2, MMP-9, and VEGF levels were lower in oxATP-treated mice than in control mice. Moreover, production of VEGF in RBL-2H3 mast cells was suppressed by treatment with oxATP. These results suggest that oxATP inhibited angiogenesis in vivo via suppression of MMP-2, MMP-9 and VEGF production. We conclude that oxATP has an anti-angiogenic effect, which would contribute to suppression of cancer growth.