Inhibitory effect of reinioside C on monocyte–endothelial cell adhesion induced by oxidized low-density lipoprotein via inhibiting NADPH oxidase/ROS/NF-κB pathway

Monocyte adhesion to activated vascular endothelial cells is the critical event in the initiation of atherosclerosis. Adhesion molecules are inflammatory markers, which are upregulated by oxidized low-density lipoprotein (ox-LDL) and play a pivotal role in atherogenesis. In present study, the effect of reinioside C, a major compound of Polygala fallax Hemsl., on adhesion of monocytes to endothelial cells induced by ox-LDL was investigated. The results showed that incubation of endothelial cells with ox-LDL (100?µg/mL) for 24 h markedly increased the expression of ICAM-1 and P-selectin and enhanced the adhesion of monocytes to endothelial cells. Pretreatment with reinioside C (1, 3, or 10?µM) dose-dependently decreased ox-LDL-induced upregulation of expression of ICAM-1 and P-selectin and the enhanced adhesion of monocytes to endothelial cells. To determine the role of NADPH oxidase/reactive oxygen species (ROS)/nuclear factor-κB (NF-κB) pathway, endothelial cells were treated with ox-LDL (100?µg/mL) for 2 h, and NADPH oxidase subunit (Nox 2 and p22^phox) mRNA expression, intracellular ROS level, and NF-κB activity were measured. The results showed that reinioside C attenuated ox-LDL-induced NADPH oxidase subunit (Nox 2 and p22^phox) mRNA expression, generation of ROS, and activation of NF-κB in endothelial cells in a dose-dependent manner; the two latter effects were inhibited by pyrollidine dithiocarbamate, the inhibitor of NF-κB. These findings suggest that reinioside C attenuates ox-LDL-induced expression of adhesion molecules (P-selectin and ICAM-1) and the adhesion of monocytes to endothelial cells by inhibiting NADPH oxidase/ROS/NF-κB pathway.     

Nangibotide attenuates osteoarthritis by inhibiting osteoblast apoptosis and TGF-β activity in subchondral bone

Inflammopharmacology - Osteoarthritis (OA) is a chronic joint disorder that causes cartilage degradation and subchondral bone abnormalities. Nangibotide, also known as LR12, is a dodecapeptide with...     

Fenofibrate decreases asymmetric dimethylarginine level in cultured endothelial cells by inhibiting NF-κB activity

Previous investigations have demonstrated that endogenous inhibitors of nitric oxide synthase (NOS), such as asymmetric dimethylarginine (ADMA), contribute importantly to endothelial dysfunction, and that fenofibrate has a protective effect on the endothelium in rats treated with low-density lipoprotein (LDL) by reducing ADMA levels. In the present study, we explored further the possible mechanism underlying inhibition of ADMA generation by fenofibrate in cultured human umbilical vein endothelial cells (HUVECs). Endothelial injury was induced in cultured HUVECs by incubation with oxidative LDL (ox-LDL) and the levels of ADMA, lactate dehydrogenase (LDH), NO and tumour necrosis factor- (TNF-) in the conditioned medium were measured. Cell viability and the activity of dimethylarginine dimethylaminohydrolase (DDAH) and nuclear factor-B (NF-B) in the cultured HUVECs were also determined. Incubation of HUVECs with ox-LDL (100 g/ml) for 24 h markedly elevated ADMA, LDH and TNF- in the conditioned medium and significantly increased the activity of NF-B, concomitantly with a significant decrease in the activity of DDAH and the content of NO. Pretreatment with fenofibrate (3, 10 or 30 M) significantly inhibited the increases in ADMA, LDH and TNF-, attenuated the decreased levels of NO and the decreased activity of DDAH and prevented the activation of NF-B. Similar effects were observed in the presence of pyrrolidine dithiocarbamate (PDTC, 10 M), an antagonist of NF-B. The beneficial effects of fenofibrate on cultured endothelial cells were abolished by MK-886, a specific peroxisome proliferator-activated receptor- (PPAR) antagonist. The present results suggest that fenofibrate inhibits ox-LDL-induced endothelial cell damage by decreasing ADMA and increasing DDAH activity, and the protective effects of fenofibrate on endothelial cells may be related to reduction of NF-B activity by activation of the PPAR receptor.     

HIF-1α and HIF-2α are critically involved in hypoxia-induced lipid accumulation in hepatocytes through reducing PGC-1α-mediated fatty acid β-oxidation

During periods of cellular hypoxia, hepatocytes adapt to consume less oxygen by shifting energy production from mitochondrial fatty acid β-oxidation to glycolysis. One of the earliest responses to pathologic hypoxia is the activation of the hypoxia-inducible factor (HIF). In the present study, we examined whether HIF-1 and HIF-2 were involved in the regulation of fatty acid synthesis and β-oxidation. We showed that hypoxia induced fat accumulation in the livers of mice and in HepG2 cells. These hypoxia-induced changes in fatty acid metabolism were mediated by suppressing fatty acid β-oxidation, without significantly influencing fatty acid synthesis. Exposing hepatocytes to 1% O₂ reduced the mRNA expression of carnitine palmitoyltransferase 1 (CPT-1), which catalyzes the rate-limiting step in the mitochondrial import of fatty acids for β-oxidation. Moreover, hypoxia exposure reduced proliferator-activated receptor-γ coactivator-1α (PGC-1α) protein levels, which plays an important role in regulation of β-oxidation. Exposure of HIF-1α or HIF-2α deficient hepatocytes to hypoxia abrogated the reduction in PGC-1α and CPT-1 expression and cellular lipid accumulation observed in normal hepatocytes exposed to hypoxia. These results suggest that both HIF-1α and HIF-2α are involved in hypoxia-induced lipid accumulation in hepatocytes via reducing PGC-1α mediated fatty acid β-oxidation.     

Salvicine, a novel topoisomerase Ⅱ inhibitor, exerts its potent anticancer activity by ROS generation

Salvicine is a novel diterpenoid quinone compound obtained by structural modification of a natural product lead isolated from a Chinese herb with potent growth inhibitory activity against a wide spectrum of human tumor cells in vitro and in mice bearing human tumor xenografts. Salvicine has also been found to have a profound cytotoxic effect on multidrug-resisitant （MDR） cells. Moreover, Salvicine significantly reduced the lung metastatic foci of MDA-MB-435 orthotopic xenograft. Recent studies demonstrated that salvicine is a novel non-intercalative topoisomerase Ⅱ （Topo Ⅱ） poison by binding to the ATPase domain, promoting DNA-Topo Ⅱ binding and inhibiting Topo Ⅱ-mediated DNA relegation and ATP hydrolysis. Further studies have indicated that salcivine-elicited ROS plays a central role in salvicine-induced cellular response including Topo Ⅱ inhibition, DNA damage, circumventing MDR and tumor cell adhesion inhibition.     

Saikosaponins-b suppresses tumor growth and angiogenesis of hepatocellular carcinoma by regulating VEGF/ERK/HIF-1α signal pathway

OBJECTIVE Angiogenesis therapy has attracted interest as a potential treatment for hepatocellular carcinoma(HCC).In this study,we investigated the anti-proliferative activities and antiangiogenesis effects of saikosaponins(SS)-b on hepatocellular carcinoma(HCC)and its regulation on VEGF/ERK/HIF-1 αsignal pathway.METHODS H22 hepatoma-bearing mice model and HepG-2 cells were used to study the anti-tumor and anti-angiogenesis effects of SS-b in vivo and in vitro.Pathological change of tumor tissue was observed by HE staining,the microvascular changes were detected by immunohistochemical method.The effects of SS-b on angiogenesis were examined by using the chick embryo chorioallantoic membrane(CAM)model.The effects of SS-b on proliferation,migration and invasion were investigated by MTT assay,scratch wound healing assay and transwell assay inhuman umbilical vein endothelial cell(HUVEC)and HepG2 cells in vitro.Vascular endothelial growth factor(VEGF),matrix metalloproteinase-2/9(MMP-2/9),hypoxia-inducible factor-1α(HIF-1α)expression and the phosphorylation of extracellular regulated kinase(ERK)were analyzed using RT-PCR and Westernblot.RESULTS SS-b effectively inhibited the tumor growth of H22 mice in vivo.The inhibitory rate of tumor was 49.1%,50.7%,66.1%in SS-b 5,10 and 20 mg·kg-1group respectively.HE staining results showed that SS-b induced tumor necrosis and nuclear dissolution in H22 mice.Moreover,SS-b also reduced the number of microvessels of tumor tissue in H22 mice significantly and suppressed the angiogenesis of CAM induced by b-FGF.SS-b had an obvious inhibitory effect on cell proliferation,migration and invasion of HUVEC cells and HepG-2 cells.These effects were associated with downregulation of the expression of MMP2/9 and suppression of VEGF/ERK/HIF-1αsignaling in H22 mice and Hep-G2 cells.CONCLUSION Our findings showed that SS-b exerts anti-tumor effects by inhibiting tumor angiogenesis via regulating VEGF/ERK/HIF-1α signal pathway in vivo and in vitro.     

HIF-1α links β-adrenoceptor agonists and pancreatic cancer cells under normoxic condition

Aim:

To examine whether β-adrenoceptor (β-AR) agonists can induce hypoxia-inducible factor (HIF)-1α accumulation which then up-regulate the expression of its target genes in pancreatic cancer cells at normoxia, and to further elucidate the mechanism involved.

Methods:

Pulse-chase assay, RT-PCR, and Western blot were employed to detect the effects of β-AR agonists and antagonists, siRNA as well as several inhibitors of signal transduction pathways on MIA PaCa2 and BxPC-3 pancreatic cancer cells.

Results:

Treatment of pancreatic cancer cell lines with β-AR agonists led to accumulation of HIF-1α and then up-regulated expression of its target genes independently of oxygen levels. The induction was partly or completely inhibited not only by β-AR antagonists but also by inhibitors of PKA transduction pathways and by siHIF-1α. Both β1-AR and β2-AR agonists produced the above-mentioned effects, but β2-AR agonist was more potent.

Conclusion:

Activation of β-AR receptor transactivates epidermal growth factor receptor (EGFR) and then elicites Akt and ERK1/2 in a PKA-dependent manner, which together up-regulate levels of HIF-1α and downstream target genes independently of oxygen level. Our data suggest a novel mechanism in pancreatic cancer cells that links β-AR and HIF-1α signaling under normoxic conditions, with implications for the control of glucose transport, angiogenesis and metastasis.     

Modulation of PGC-1α activity as a treatment for metabolic and muscle-related diseases

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