Total Flavones of Abelmoschus manihot Exhibits Pro-Angiogenic Activity by Activating the VEGF-A/VEGFR2-PI3K/Akt Signaling Axis.

Angiogenesis is a process of new blood vessel formation from pre-existing vessels. Vascular endothelial growth factor-A (VEGF-A) binds to VEGF receptor-2 (VEGFR2) and thus activation of phosphatidylinositol 3-kinase (PI3K)/Akt pathway play a central role in angiogenesis. Total flavones of Abelmoschus manihot (TFA), the major active component of the traditional Chinese herb Abelmoschus manihot, display novel pro-angiogenic activity. However, little information concerning its underlying mechanism is available. Here we investigate the pro-angiogenesis of TFA with the aim of understanding its mechanism of action. Human umbilical vein endothelial cells (HUVECs) and the chick chorioallantoic membrane (CAM) model were used to evaluate pro-angiogenesis of TFA using cell viability, wounding healing, transwell invasion, tube formation, RT-qPCR and Western blot methods. LY294002, a PI3K inhibitor, was used to interfere with PI3K/Akt pathway signal for assessing the underlying mechanism. Results in vitro indicated TFA obviously promoted HUVECs proliferation, migration, invasion and tube formation. Furthermore, TFA markedly augmented PI3K and Akt phosphorylation and up-regulated VEGF-A and VEGFR2 expression in HUVECs. However, pre-treatment with LY294002 not only markedly attenuated TFA-induced cells proliferation, migration, invasion and tube formation, but also significantly abolished TFA-induced VEGF-A and VEGFR2 over-expression as well as PI3K and Akt phosphorylation. Experiments in CAM model showed TFA significantly promoted the formation of branched blood vessels and was dramatically suppressed by LY294002. Taken together, TFA promoted angiogenesis both in vitro and in vivo which, however, were counteracted by LY294002, suggesting at least in part, TFA exhibits pro-angiogenic activity by activating the VEGF-A/VEGFR2-PI3K/Akt signaling axis.

[Effects of ligustrazine injection on high glucose-induced type I collagen, matrix metalloproteinase-1 and tissue inhibitor of metalloproteinase-1 expressions in human peritoneal mesothelial cells in vitro].

OBJECTIVE: To investigate the effects of ligustrazine injection on type I collagen, matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) expressions in human peritoneal mesothelial cells (HPMCs) cultured in high glucose conditions. METHODS: HPMCs were isolated from human omenta by trypsin digestion method and subcultured. Then, the HPMCs were divided into normal control group, high glucose group and high glucose plus low-, medium- and high-dose ligustrazine (10, 20 and 40 mg/L ligustrazine respectively) groups. Semi-quantitative reverse transcription-polymerase chain reaction was used to detect the expressions of type I collagen, MMP-1 and TIMP-1 mRNAs in HPMCs. Proteins of type I collagen, MMP-1 and TIMP-1 in culture supernatants were measured by enzyme-linked immunosorbent assay (ELISA). Cell protein concentration was measured by trace bicinchoninic acid method to correct the ELISA assay results. RESULTS: Ligustrazine injection could significantly decrease high glucose-induced type I collagen and TIMP-1 expressions in a dose-dependent manner both in protein and gene levels (P<0.05, P<0.01). In addition, medium- and high-dose ligustrazine injection could significantly increase MMP-1 expression which was inhibited by high glucose concentrations (P<0.05). CONCLUSION: Ligustrazine injection does not only decrease type I collagen synthesis, but also promote its degradation by modulating unbalanced MMP-1/TIMP-1 expression in HPMCs cultured in high glucose conditions.