Oridonin Inhibits Tumor Growth and Metastasis through Anti-Angiogenesis by Blocking the Notch Signaling

While significant progress has been made in understanding the anti-inflammatory and anti-proliferative effects of the natural diterpenoid component Oridonin on tumor cells, little is known about its effect on tumor angiogenesis or metastasis and on the underlying molecular mechanisms. In this study, Oridonin significantly suppressed human umbilical vascular endothelial cells (HUVECs) proliferation, migration, and apillary-like structure formation in vitro. Using aortic ring assay and mouse corneal angiogenesis model, we found that Oridonin inhibited angiogenesis ex vivo and in vivo. In our animal experiments, Oridonin impeded tumor growth and metastasis. Immunohistochemistry analysis further revealed that the expression of CD31 and vWF protein in xenografts was remarkably decreased by the Oridonin. Furthermore, Oridonin reinforced endothelial cell-cell junction and impaired breast cancer cell transendothelial migration. Mechanistically, Oridonin not only down-regulated Jagged2 expression and Notch1 activity but also decreased the expression of their target genes. In conclusion, our results demonstrated an original role of Oridonin in inhibiting tumor angiogenesis and propose a mechanism. This study also provides new evidence supporting the central role of Notch in tumor angiogenesis and suggests that Oridonin could be a potential drug candidate for angiogenesis related diseases.