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The morbidity and mortality of cardiovascular diseases rank the first in the world. Therapeutic angiogenesis has become a valuable tool for treating cardiovascular diseases by promoting the establishment of collateral circulation in ischemic region and increasing blood flow supply. The present study aims to investigate the effects of ginsenoside Rb1 on angiogenesis and reveal the mechanism based on the glycolytic enzyme pyruvate kinase M2 isoform (PKM2).
Human umbilical vein endothelial cells (HUVECs) were freshly isolated from human umbilical cord vein. Angiogenic potential was assessed by the spontaneous formation of capillary-like structures by HUVECs on growth factor-reduced matrigel in vitro and mouse model of hindlimb ischemia was constructed to evaluate blood flow in vivo. Western blots were used to detect the effects of ginsenoside Rb1 on the expression of PKM2 and the other enzymes in glycolysis. Using shRNA to knock down the expression of PKM2, the cell proliferation, migration, apoptosis and angiogenesis were evaluated.
Our results showed that ginsenoside Rb1 significantly promoted the proliferation and angiogenesis of HUVECs by enhanced glycolysis. The lactate production increased and key enzymes involved in glycolysis upregulated, including PKM2, HK2, PFK1, TPI1 and LDHA. To identify whether PKM2 was the key mediator in Rb1-induced angiogenesis, we knocked down the expression of PKM2 using shRNA. The proliferation rate decreased, while the cell apoptosis and migration rate increased compared to the control. In vitro tube formation and in vivo hindlimb ischemia assay, sh-PKM2 both could inhibit the angiogenesis.
The findings in this study are of significant importance and may provide valuable information for better understanding the function of ginsenoside Rb1. PKM2 may represent novel therapeutic targets for the treatment of angiogenic cardiovascular diseases.