Ginsenoside Rh2 inhibits breast cancer cell growth via ERß-TNFα pathway.

Ginsenoside Rh2 is one of rare panaxidiols extracted from Panax ginseng and a potential estrogen receptor ligand that exhibits moderate estrogenic activity. However, the effect of Rh2 on growth inhibition and its underlying molecular mechanism in human breast cells are not fully understood. In this study, we tested cell viability by MTT and colony formation assays. Cell growth and cell cycle were determined to investigate the effect of ginsenoside Rh2 by flow cytometry. The expressions of estrogen receptors (ERs), TNFα, and apoptosis-related proteins were detected by qPCR and western blot analysis. The mechanisms of ERα and ERß action were determined using transfection and inhibitors. Antitumor effect of ginsenoside Rh2 against MCF-7 cells was investigated in xenograft mice. Our results showed that ginsenoside Rh2 induced apoptosis and G1/S phase arrest in MCF-7 cells. Treatment of cells with ginsenoside Rh2 down-regulated protein levels of ERα, and up-regulated mRNA and protein levels of ERß and TNFα. We also found that ginsenoside Rh2-induced TNFα over-expression is through up-regulation of ERß initiated by ginsenoside Rh2. Furthermore, ginsenoside Rh2 induced MCF-7 cell apoptosis via estrogen receptor ß-TNFα pathway in vivo. These results demonstrate that ginsenoside Rh2 promotes TNFα-induced apoptosis and G1/S phase arrest via regulation of ERß.

The anti-angiogenic effect and novel mechanisms of action of Combretastatin A-4.

Combretastatin A-4 (CA4) is the lead compound of a relatively new class of vascular disrupting agents that target existing tumor blood vessels. Recent studies showed the CA4 might inhibit angiogenesis. However, the underlying molecular mechanisms by which CA4 exerts its anti-angiogenic effects are not fully understood. In this study, we revealed that CA4 inhibited vascular endothelial growth factor (VEGF)-induced proliferation, migration and capillary-like tube formation of human umbilical vascular endothelial cells (HUVECs). In in vivo assay, CA4 suppressed neovascularization in chicken chorioallantoic membrane (CAM) model and decreased the microvessel density in tumor tissues of a breast cancer MCF-7 xenograft mouse model. In addition, CA4 decreased the expression level and secretion of VEGF both in MCF-7 cells and HUVECs under hypoxia, as well as the activation of VEGFR-2 and its downstream signaling mediators following VEGF stimulation in HUVECs. Moreover, VEGF and VEGFR-2 expression in tumor tissues of the mouse xenograft model were down-regulated following CA4 treatment. Taken together, results from the current work provide clear evidence that CA4 functions in endothelial cell system to inhibit angiogenesis, at least in part, by attenuating VEGF/VEGFR-2 signaling pathway.