Proteasome Inhibitor MG132 Inhibits Angiogenesis in Pancreatic Cancer by Blocking NF-κB Activity

Since angiogenesis enables solid tumors, including pancreatic cancer (PaCa), to grow and metastasize, the development of anti-angiogenic agents is currently one of the urgent issues. Proteasome inhibitors are well known for inhibiting nuclear factor-kappa B (NF-κB) activity in various cancer cells, but little is known about their biologic mechanisms against angiogenesis in PaCa. We divided human PaCa cell lines into high-angiogenic (BxPC-3 and SW 1990) and low-angiogenic (MIA PaCa-2 and Capan-2) groups. The high-angiogenic PaCa cell lines constitutively expressed high NF-κB activity and produced high levels of vascular endothelial growth factor (VEGF) and interleukin 8 (IL-8). The conditioned media from BxPC-3 significantly enhanced both proliferation of and tube formation by human umbilical vein endothelial cells (HUVECs) and these enhancements were significantly inhibited by the proteasome inhibitor MG132 treatment. Collectively, MG132 blocked PaCa-derived VEGF and IL-8 production through inhibition of NF-κB activity. Thus, proteasome inhibitors may prove beneficial as anti-angiogenic therapy for PaCa. Our studies show that MG132, a proteasome inhibitor, significantly blocked pancreatic-cancer-associated angiogenesis through inhibition of NF-κB and NF-κB-dependent proangiogenic gene products VEGF and IL-8.     

Inhibition of aldose reductase prevents angiogenesis in vitro and in vivo

We have recently shown that aldose reductase (AR, EC 1.1.1.21) a nicotinamide adenine dinucleotide phosphate-dependent aldo–keto reductase, known to be involved in oxidative stress-signaling, prevents human colon cancer cell growth in culture as well as in nude mice xenografts. Inhibition of AR also prevents azoxymethane-induced aberrant crypt foci formation in mice. In order to understand the chemopreventive mechanism(s) of AR inhibition in colon cancer, we have investigated the role of AR in the mediation of angiogenic signals in vitro and in vivo models. Our results show that inhibition of AR significantly prevented the VEGF- and FGF -induced proliferation and expression of proliferative marker Ki67 in the human umbilical vein endothelial cells (HUVEC). Further, AR inhibition or ablation with siRNA prevented the VEGF- and FGF –induced invasion and migration in HUVEC. AR inhibition also prevented the VEGF- and FGF- induced secretion/expression of IL-6, MMP2, MMP9, ICAM, and VCAM. The anti-angiogenic feature of AR inhibition in HUVEC was associated with inactivation of PI3 K/AKT and NF-κB (p65) and suppression of VEGF receptor 2 protein levels. Most importantly, matrigel plug model of angiogenesis in rats showed that inhibition of AR prevented infiltration of blood cells, invasion, migration and formation of capillary like structures, and expression of blood vessels markers CD31 and vWF. Thus, our results demonstrate that AR inhibitors could be novel agents to prevent angiogenesis.     

Inhibition of Immune-Mediated Concanavalin A-Induced Liver Damage by Free-Radical Scavengers

Background/Aims The aims of the present study were to elucidate whether oxidative stress has a role in Con A-induced hepatitis and to examine if antioxidants may protect against liver damage in this model. Methods Hepatitis was induced in Balb/c mice by administration of Con A (18 mg/kg) to the tail vein. Liver enzymes and histology were determined 24 h after Con A injection. Tumor necrosis factor alpha (TNFα) and interleukin-10 (IL-10) levels were assayed 2 h after Con A injection. Hepatic malondialdehyde levels were measured at 1, 3, 8, 12, 18, and 24 h after Con A injection in order to examine the timing of free-radicals formation. Nuclear factor kappa B (NF-κβ) activation was determined by electrophoresis mobility shift assay (EMSA) 1 and 2 h after Con A injection. In separate experiments, mice were pretreated with either dimethylsulfoxide or dimethylthiourea before Con A inoculation. The antioxidant and NF-κβ inhibitor pyrrolidine dithiocarbamate (PDTC) was used as positive control. Results Hepatic malondialdehyde levels increased 12, 18, and 24 h after Con A inoculation but not earlier. Serum levels of liver enzymes and TNFα, hepatic malondialdehyde, and protein carbonyls and the histologic necroinflammatory score were significantly reduced in the antioxidants-treated mice, while IL-10 levels were increased. Dimethylsulfoxide, dimethylthiourea, and PDTC inhibited oxidative stress, but only PDTC inhibited Con A-induced NF-κB activation. Conclusions Reactive oxygen species play a role in immune-mediated Con A-induced hepatitis probably secondary to immune-mediated liver damage. Scavenging of reactive oxygen species by antioxidants prevents hepatitis independently of NF-κB inhibition and may be a new therapeutic target in this experimental model.     

FGF-inducible 14-kDa protein (Fn14) is regulated via the RhoA/ROCK kinase pathway in cardiomyocytes and mediates nuclear factor-kappaB activation by TWEAK

Proinflammatory cytokines, including TNF family members, have been shown to play a critical role in cardiac remodeling. FGF-inducible 14-kDa protein (Fn14, TNFrsf12a or TWEAKR) is the smallest member of the TNF-receptor family. Currently, little is known about the functional role of Fn14 and its only known ligand TNF-like weak inducer of apoptosis (TWEAK) in the heart. We therefore evaluated the expression and regulation of Fn14 in cardiomyocytes and in experimental myocardial infarction. In order to study the regulation of Fn14, myocardial infarction was induced in CD-1 mice and neonatal rat cardiomyocytes were used for in vitro studies. TWEAK and Fn14 were markedly upregulated in the remodeling myocardium after experimental myocardial infarction in vivo. Likewise, fibroblast growth factor 1, norepinephrine and angiotensin II as well as mechanical stretch were able to strongly induce Fn14 expression in cardiomyocytes. This induction is mediated via the Rho/ROCK pathway, since the known inhibitors C3 exoenzyme for RhoA and Y27632 for ROCK prevented the upregulation of Fn14 in cardiomyocytes. Consistently, pretreatment of cardiomyocytes with siRNA against Rho A and ROCK also abolished Fn14 induction. Moreover, stimulation of cardiomyocytes with TWEAK promoted nuclear translocation of NF-κB and subsequent induction of NF-κB dependent genes such as RANTES and MCP-1. Conversely, when cells were pretreated with siRNA against Fn14, NF-κB activation by TWEAK was inhibited. We here provide the first evidence of a stress-induced regulation of the TWEAK/Fn14 axis in cardiomyocytes implying a role of the TWEAK/Fn14 pathway in cardiac remodeling.     

Gene Deletion of NF-κB p105 Enhances Neointima Formation in a Mouse Model of Carotid Artery Injury

Summary The role of nuclear factor kappa-B (NF-κB) p105 for vascular inflammatory gene expression and neointima formation after arterial injury was studied. Mice carotid arteries were injured by ligation. Vascular NF-κB activation was monitored using a NF-κB luciferase reporter mouse. Mice with gene deletion of the NF-κB p105 subunit (p50 precursor) and the corresponding wild types were assessed for vascular gene expression and neointimal hyperplasia. NF-κB was activated in the injured vessel wall in wild type mice, and this was accompanied by increased expression of the proinflammatory genes tumor necrosis factor alpha, interleukin 1 beta, and inducible nitric oxide synthase. In contrast, NF-κB p105 knockout mice had reduced expression of the inflammatory genes and enhanced neointima formation four weeks after ligation. Basic fibroblast growth factor (bFGF) gene expression increased after arterial ligation. A higher percentage of bFGF positive cells were found in lesions from NF-κB p105 knock out mice. These data indicate that the p105 subunit of NF-κB plays an essential role in vascular healing, and defects in NF-κB p105 promote neointima hyperplasia.     

Monocyte chemoattractant protein-1 has prosclerotic effects both in a mouse model of experimental diabetes and in vitro in human mesangial cells

Aims/hypothesis Diabetic nephropathy is characterised by mesangial extracellular matrix accumulation. Monocyte chemoattractant protein-1 (MCP-1), a chemokine promoting monocyte infiltration, is upregulated in the diabetic glomerulus. We performed in vitro and in vivo studies to examine whether MCP-1 may have prosclerotic actions in the setting of diabetes, presumably via its receptor, chemokine (C-C motif) receptor 2 (CCR2), which has been described in mesangial cells. Methods Human mesangial cells were exposed to recombinant human (rh)-MCP-1 (100 ng/ml) for 12, 24 and 48 h and to rh-MCP-1 (10, 100 and 200 ng/ml) for 24 h. Fibronectin, collagen IV and transforming growth factor, beta 1 (TGF-β1) protein levels were measured by ELISA and pericellular polymeric fibronectin levels by western blotting. The intracellular mechanisms were investigated using specific inhibitors for CCR2, nuclear factor kappa B (NF-κB), p38 mitogen-activated protein kinase and protein kinase C, and an anti-TGF-β1 blocking antibody. In both non-diabetic and streptozotocin-induced diabetic mice that were deficient or not in MCP-1, glomerular fibronectin accumulation was examined by immunohistochemistry, while cortical Tgf-β1 (also known as Tgfb1) and fibronectin mRNA and protein levels were examined by real-time PCR and western blotting. Results In mesangial cells, MCP-1 binding to CCR2 induced a 2.5-fold increase in fibronectin protein levels at 24 h followed by a rise in pericellular fibronectin, whereas no changes were seen in collagen IV production. MCP-1-induced fibronectin production was TGF-β1- and NF-κB-dependent. In diabetic mice, loss of MCP-1 diminished glomerular fibronectin protein production and both renal cortical Tgf-β1 and fibronectin mRNA and protein levels. Conclusions/interpretation Our in vitro and in vivo findings indicate a role for the MCP-1/CCR2 system in fibronectin deposition in the diabetic glomerulus, providing a new therapeutic target for diabetic nephropathy.     

Synthetic Serine Protease Inhibitor,Gabexate Mesilate,Prevents Nuclear Factor-κB Activation and Increases TNF-α-Mediated Apoptosis in Human Pancreatic Cancer Cells

Gabexate mesilate (GM), a synthetic serine protease inhibitor, suppresses nuclear factor-κB (NF-κB) activity in human monocytes or human umbilical vein endothelial cells (HUVECs). In this study we examine whether GM also suppresses NF-κB activation and induces apoptosis in human pancreatic cancer cell lines. The addition of tumor necrosis factor α (TNF-α) did not change the rates of growth of BxPC-3 and MIA PaCa-2. However, in the presence of GM and TNF-α, proliferation decreased in a dose-dependent manner. GM- and TNF-α-treated cells exhibited morphologic changes indicative of apoptosis, including chromatin condensation and nuclear fragmentation. The NF-κB activity of both cell lines was increased by the addition of TNF-α, while TNF-α-induced NF-κB activity was suppressed by prestimulation with GM in a dose-dependent manner. Caspase 3 and 7 activity was significantly increased by TNF-α with GM stimulation. Furthermore, GM also suppressed the invasive potential of both cell lines. These results indicate that GM inhibits TNF-α-induced NF-κB activation and enhances apoptosis in human pancreatic cancer cell lines.     

IL-1β-induced pro-apoptotic signalling is facilitated by NCAM/FGF receptor signalling and inhibited by the C3d ligand in the INS-1E rat beta cell line

Aims/hypothesis IL-1β released from immune cells induces beta cell pro-apoptotic signalling via mitogen-activated protein kinases (MAPKs) and nuclear factor-κB (NF-κB). In neurons, the neural cell adhesion molecule (NCAM) signals to several elements involved in IL-1β-induced pro-apoptotic signalling in beta cells. Pancreatic beta cells express NCAM, but its biological effects in these cells are unclear. The aim of this study was to investigate whether there is cross-talk between NCAM signalling and cytokine-induced pro-apoptotic signalling.Materials and methods Western blotting was used to investigate levels of NCAM and inducible nitric oxide synthase, phosphorylation of Src and MAPKs, and cleavage of caspase-3. MAPK activity was investigated with an in vitro kinase assay. Apoptosis was detected by cleaved caspase-3 and a Cell Death Detection ELISA^plus assay. NCAM-induced fibroblast growth factor receptor (FGFR) activation was investigated in NCAM^−/− Trex293 cells where FGFR phosphorylation was measured by Western blotting after NCAM transfection.Results Pre-exposure of INS-1E cells to the FGFR-inhibitor SU5402, but not to the Src-inhibitor PP2, dose-dependently inhibited IL-1β-mediated MAPK activity. A synthetic peptide, C3d, reported to bind NCAM, did not activate MAPK or Akt as reported in neurons but inhibited IL-1β-induced MAPK activity, thereby mimicking the effect of SU5402. Furthermore, C3d inhibited NCAM-induced FGFR phosphorylation and apoptosis induced by IL-1β plus IFN-γ, but did not affect IL-1β-induced NF-κB signalling.Conclusions/interpretation We suggest that NCAM signalling through FGFR is required for efficient IL-1β pro-apoptotic signalling by facilitating IL-1β-induced MAPK activation downstream of the NF-κB-MAPK branching point. Further, these data identify a novel function of C3d as an inhibitor of NCAM-induced FGFR activity and of IL-1β-induced MAPK activation in beta cells.     

Nerve growth factor/nuclear factor-κB pathway as a therapeutic target in breast cancer

Introduction  Nuclear factor-κB pathway (NF-κB) is activated in many breast cancers. NF-кB has interactions with other pathways such as the nerve growth factor (NGF) pathway, which is involved in the survival and proliferation of breast cancer cells. NGF treatment of breast cancer cells activates NF-κB resulting in the inhibition of ceramide-induced apoptosis. NGF effects on apoptosis and cell proliferation are mediated through p75NTR and p140TrkA receptors, respectively. In this study we investigate the NGF/NF-κB pathway as a therapeutic target in breast cancer. Results  We demonstrate that p75NTR inhibitor Pep5, p140TrkA inhibitor K-252a, and NF-κB inhibitor BAY11-7085 have pro-apoptotic and anti-proliferation activities in breast cancer cells. We also show a synergy in combining the NGF receptor inhibitors with the conventional breast cancer treatments tamoxifen and taxol. Conclusion   These data suggest that NGF/NF-κB pathway is a potential therapeutic target in breast cancer.     

Inhibition of nuclear factor-κB by hyaluronan in rheumatoid chondrocytes stimulated with COOH-terminal heparin-binding fibronectin fragment

The aim of this study was to examine the inhibitory effect of high molecular weight hyaluronan (HA) on nuclear factor (NF)-κB activation by COOH-terminal heparin-binding fibronectin fragment (HBFN-f) in rheumatoid arthritis (RA) chondrocytes. When RA chondrocytes in monolayer or cartilage explants were cultured with HBFN-f, the fragment stimulated the phosphorylation and nuclear translocation of NF-κB, leading to nitric oxide (NO) production in association with inducible form of NO synthase (iNOS) up-regulation. Inhibition studies with NF-κB inhibitors indicated the requirement of NF-κB for HBFN-f-induced NO production. Pretreatment with 2700 kDa HA resulted in significant suppression of NF-κB activation by HBFN-f. HA also inhibited HBFN-f-stimulated NO production with down-regulation of iNOS. The present study clearly demonstrated that high molecular weight HA suppressed HBFN-f-activated NF-κB in RA chondrocytes. HA could down-regulate the catabolic action of fibronectin fragments like HBFN-f in RA joints as a potent NF-κB inhibitor.     

Taurocholate Potentiates Ethanol-Induced NF-κB Activation and Inhibits Caspase-3 Activity in Cultured Rat Gastric Mucosal Cells

We have previously shown that ethanol (EtOH) induces protective NF-κB activation in gastric surface epithelial cells. This study investigates the defense systems in rat gastric mucosal cells (RGM-1) exposed simultaneously to EtOH and taurocholate (TC) or acetylsalicylic acid (ASA). Simultaneous exposure to ASA and EtOH increased EtOH-induced caspase-3 activity and decreased cell viability, indicating synergetic damaging action. Simultaneous exposure to TC (5 mM) with EtOH (5%) increased EtOH-induced NF-κB activation, opposing EtOH-induced decrease in cell membrane integrity and in cell viability as shown by decreasing RelA expression with siRNA technique. Low doses of TC decreased the EtOH (5%) induced caspase-3 activity independently from NF-κB pathway and inhibited EtOH-induced decrease in caspase-3 precursor protein levels, also indicating the inhibition of caspase-3 pathway. The TC (5 mM)-induced protection in EtOH exposed tissues seems to have two distinct pathways, inhibition of apoptosis and enhancement of NF-κB signaling.     

Anti-Angiogenic Activity of Contortrostatin, a Disintegrin from Agkistrodon Contortrix Contortrix Snake Venom

Previous work in our laboratory has shown that contortrostatin (CN), a disintegrin from southern copperhead snake venom, possess anti-angiogenic activity. In the present study we further examined the anti-angiogenic activity of CN, focusing on the mechanisms of CN inhibition of angiogenesis. CN inhibited migration and invasion, and significantly altered Matrigel-induced tube formation of human umbilical vein endothelial cells (HUVEC), but did not affect cell viability, or MMP-2 and MMP-9 activity. Immunocytochemistry of HUVEC revealed that CN disrupted actin cytoskeleton and altered VE-cadherin distribution at cell-cell contacts. CN downregulated focal adhesion kinase (FAK) and paxillin tyrosine phosphorylation in adherent HUVEC. There was also significant inhibition of angiogenesis in vivo by CN as assessed by implanting Matrigel plugs in C57 mice and measuring ingrowth of blood vessels using either factor VIII staining or hemoglobin determination. In conclusion, the present findings confirm our earlier studies and demonstrate conclusively that CN possess strong anti-angiogenic activity in vitro and in vivo.