The insulin-like growth factor (IGF) signaling pathway plays a crucial role in the regulation of cell growth, differentiation, apoptosis, and aging. IGF-binding proteins (IGFBPs) are important members of the IGF axis. IGFBP-5 is up-regulated during cellular senescence in human dermal fibroblasts and endothelial cells, but the function of IGFBP-5 in cellular senescence is unknown. Here we show that IGFBP-5 plays important roles in the regulation of cellular senescence. Knockdown of IGFBP-5 in old human umbilical endothelial cells (HUVECs) with IGFBP-5 micro-RNA lentivirus caused partial reduction of a variety of senescent phenotypes, such as changes in cell morphology, increases in cell proliferation, and decreases in senescence-associated beta-galactosidase (SA-beta-gal) staining. In addition, treatment with IGFBP-5 protein or up-regulation of IGFBP-5 in young cells accelerates cellular senescence, as confirmed by cell proliferation and SA-beta-gal staining. Premature senescence induced by IGFBP-5 up-regulation in young cells was rescued by knockdown of p53, but not by knockdown of p16. Furthermore, atherosclerotic arteries exhibited strong IGFBP-5-positive staining along intimal plaques. These results suggest that IGFBP-5 plays a role in the regulation of cellular senescence via a p53-dependent pathway and in aging-associated vascular diseases.
Angiogenesis is associated with growth, invasion, and metastasis of human solid tumors. Aberrant activation of endothelial cells and induction of microvascular permeability by a vascular endothelial growth factor (VEGF) receptor-2 (VEGFR-2) signaling pathway is observed in pathological angiogenesis including tumor, wound healing, arthritis, psoriasis, diabetic retinopathy, and others. Here, we show that GM3 regulated the activity of various downstream signaling pathways and biological events through the inhibition of VEGF-stimulated VEGFR-2 activation in vascular endothelial cells in vitro. Furthermore, GM3 strongly blocked VEGF-induced neovascularization in vivo, in models including the chick chorioallantoic membrane and Matrigel plug assay. Interestingly, GM3 suppressed VEGF-induced VEGFR-2 activation by blocking its dimerization and also blocked the binding of VEGF to VEGFR-2 through a GM3-specific interaction with the extracellular domain of VEGFR-2, but not with VEGF. Primary tumor growth in mice was inhibited by subcutaneous injection of GM3. Immunohistochemical analyses showed GM3 inhibition of angiogenesis and tumor cell proliferation. GM3 also resulted in the suppression of VEGF-stimulated microvessel permeability in mouse skin capillaries. These results suggest that GM3 inhibits VEGFR-2-mediated changes in vascular endothelial cell function and angiogenesis, and might be of value in anti-angiogenic therapy.
BackgroundOur previous study suggested that licorice has anti-inflammatory activity in lipopolysaccharide-stimulated microglial cells and anti-oxidative activity in tert-butyl hydroperoxide–induced oxidative liver damage. In this study, we evaluated the effect of licorice on chronic alcohol-induced fatty liver injury mediated by inflammation and oxidative stress.MethodsRaw licorice was extracted, and quantitative and qualitative analysis of its components was performed by using LC–MS/MS. Mice were fed a liquid alcohol diet with or without licorice for 4 weeks.ResultsWe have standardized 70 % fermented ethanol extracted licorice and confirmed by LC-MS/MS as glycyrrhizic acid (GA), 15.77 ± 0.34 μg/mg; liquiritin (LQ), 14.55 ± 0.42 μg/mg; and liquiritigenin (LG), 1.34 ± 0.02 μg/mg, respectively. Alcohol consumption increased serum alanine aminotransferase and aspartate aminotransferase activities and the levels of triglycerides and tumor necrosis factor (TNF)-α. Lipid accumulation in the liver was also markedly induced, whereas the glutathione level was reduced. All these alcohol-induced changes were effectively inhibited by licorice treatment. In particular, the hepatic glutathione level was restored and alcohol-induced TNF-α production was significantly inhibited by licorice.ConclusionTaken together, our data suggests that protective effect of licorice against alcohol-induced liver injury may be attributed to its anti-inflammatory activity and enhancement of antioxidant defense.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-016-0997-0) contains supplementary material, which is available to authorized users.
Systemic transplantation of adipose-derived stem cells (ASCs) is emerging as a novel therapeutic option for functional recovery of diverse damaged tissues. This study investigated the effects of systemic transplantation of human ASCs (hASCs) on bone repair. We found that hASCs secrete various bone cell-activating factors, including hepatocyte growth factor and extracellular matrix proteins. Systemic transplantation of hASCs into ovariectomized mice induced an increased number of both osteoblasts and osteoclasts in bone tissue and thereby prevented bone loss. We also observed that conditioned medium from hASCs is capable of stimulating proliferation and differentiation of osteoblasts via Smad/extracellular signal-regulated kinase (ERK)/JNK (c-jun NH2-terminal kinase) activation as well as survival and differentiation of osteoclasts via ERK/JNK/p38 activation in vitro. Overall, our findings suggest that paracrine factors secreted from hASCs improve bone repair and that hASCs can be a valuable tool for use in osteoporosis therapy.
The oligosaccharides in human milk have various biological functions. However, the molecular mechanism(s) underlying the anti-angiogenic action of sialylated human milk oligosaccharides (HMOs) are still unclear. Here, we show that siallylactose (SL) found in human milk can inhibit the activation of vascular endothelial growth factor (VEGF)-mediated VEGF receptor-2 (VEGFR-2) by binding to its VEGF binding site (second and third IgG-like domains), thus blocking downstream signal activation. SL also inhibits growth of VEGF-stimulated endothelial cells. In endothelial cells treated with VEGF, SL diminished tube formation, migration, and the arrangement of actin filament. In addition, SL clearly suppressed VEGF-induced neovascularization in an in vivo Matrigel plug assay. Notably, SL prevented the growth of tumor cells, and angiogenesis on tumor tissues in in vivo mice models allotransplanted with Lewis lung carcinoma, melanoma, and colon carcinoma cells. Taken together, we have demonstrated that the sialylated milk oligosaccharide sialyllactose functions as an inhibitor of angiogenesis through suppression of VEGF-mediated VEGFR-2 activation in endothelial cells, Accordingly, it could be a novel candidate for the development of anti-angiogenic drugs without any side effects.
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