A cassaine diterpene alkaloid, 3β-acetyl-nor-erythrophlamide, suppresses VEGF-induced angiogenesis and tumor growth via inhibiting eNOS activation

Angiogenesis is one of the hallmarks of cancer, playing an essential role in tumor growth, invasion, and metastasis. 3β-Acetyl-nor-erythrophlamide (3-ANE), a cassaine diterpene alkaloid compound from Erythrophleum fordii, exerts various pharmacological effects, including antitumor activity. However, the effects of 3-ANE on tumor angiogenesis and its potential molecular mechanism are still unknown. Here, we demonstrated that 3-ANE inhibited the vascular endothelial growth factor (VEGF)-mediated proliferation, migration, invasion, and capillary-like tube formation of human umbilical vascular endothelial cells (HUVECs), without inducing apoptosis. We also found that 3-ANE blocked angiogenesis in vivo, and suppressed tumor angiogenesis and human lung adenocarcinoma growth in the xenograft tumor model. Furthermore, we showed that 3-ANE blocked VEGF-mediated endothelial nitric oxide synthase (eNOS) phosphorylation, vascular permeability and NO production in HUVECs, via disrupting the VEGF-induced association of eNOS and heat-shock protein 90 (HSP90). Our studies therefore provide the first evidence that 3-ANE inhibits tumor angiogenesis by inhibiting the VEGF-mediated eNOS activation and NO production, and 3-ANE could be a potential candidate in angiogenesis-related disease therapy.