Tanshinone I inhibits tumor angiogenesis by reducing STAT3 phosphorylation at TYR705 and hypoxia-induced HIF-1α accumulation in both endothelial and tumor cells
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Yan Wang1,2, Jia-Xin Li1, Ying-Qing Wang1, Ze-Hong Miao1
1Division of Antitumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
2College of Pharmacy, Nanchang University, Nanchang 330006, China
Ze-Hong Miao, e-mail: email@example.com
Ying-Qing Wang, e-mail: firstname.lastname@example.org
Keywords: tanshinone I, angiogenesis, Stat3, HIF-1α, VEGF
Received: February 15, 2015 Accepted: March 23, 2015 Published: April 10, 2015
Tanshinone I (Tanshinone-1), a major active principle of Salvia miltiorrhiza (Danshen), has been shown to overcome tumor drug resistance and metastasis. Here we report that tanshinone-1 inhibits angiogenesis. Tanshinone-1 inhibited proliferation, migration and tube formation of vascular endothelial cells, rat aortic ring sprouting and the neovascularization of the chick chorioallantoic membrane in a concentration-dependent manner. In endothelial cells, tanshinone-1 almost completely inhibited phosphorylation of Stat3 at Tyr705 regardless of hypoxia or normoxia but only slightly decreased the hypoxia-induced HIF-1α accumulation. In tumor cells, contrastively, tanshinone-1 could not only make phosphorylation of Stat3 at Tyr705 disappear but also reduce the hypoxia-induced accumulation of HIF-1α to its baseline levels at normoxia. Consequently, VEGF secretion from tumor cells was reduced, which could potentiate the direct inhibition of tanshinone-1 on endothelial cells. Together with its overcoming tumor drug resistance and metastasis, our results reveal unique characteristics of tanshinone-1 and its improved derivatives as promising angiogenesis inhibitors.
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