Withaferin A Suppresses Liver Tumor Growth in a Nude Mouse Model by Downregulation of Cell Signaling Pathway Leading to Invasion and Angiogenesis

Purpose: To investigate the effect of withaferin A on tumor growth and metastasis in liver in a nude mouse model.
Methods: Withaferin A was injected through a portal vein to the orthotopic liver tumor in a nude mice model. Xenogen in vivo imaging system was used to monitor tumor growth and metastasis. The effect of withaferin A on tumor volume, invasive growth pattern, expression of Pyk2, upregulation of BAX/P5 apoptotic signaling and ROCK/IP10/VEGF pathway along with cytoskeletal protein act in projection formation was studied. Tumor/non-tumor margin was examined under electron microscopy. In addition, the direct effect of withaferin A on liver cancer cells and endothelial cells was further investigated.
Results: A significant inhibition of tumor growth and lower incidence of lung metastasis was observed after withaferin A treatment. Withaferin A treatment led to a decrease in the incidence of intrahepatic metastasis from 90(9 of 10) to 10 % (1 of 10, p = 0.041). There was decrease in macrophage infiltration in the liver tumors and vessels. Western blot analysis revealed inhibition of expression of Pyk2, ROCK1 protein and VEGF. Electron microscopy showed tumor vascular endothelial cell damage and significant necrosis of tumor tissues. It also suppressed formation of cytoskeletal protein actin projection involved in cell migration.
Conclusion: Withaferin A inhibits liver tumor invasion and angiogenesis by downregulation of cell signalling pathway leading to invasion and angiogenesis. Therefore, withaferin A is a promising candidate for the treatment of liver tumor invasion and angiogenesis.

Keywords
Withaferin A; Macrophage; Lung metastasis; Angiogenesis; Vascular endothelial growth factor; Rho kinase; Withania somnifera