IRX1 hypomethylation promotes osteosarcoma metastasis via induction of CXCL14/NF-κB signaling

Osteosarcoma is a common malignant bone tumor with a propensity to metastasize to the lungs. Epigenetic abnormalities have been demonstrated to underlie osteosarcoma development; however, the epigenetic mechanisms that are involved in metastasis are not yet clear. Here, we analyzed 2 syngeneic primary human osteosarcoma cell lines that exhibit disparate metastatic potential for differences in epigenetic modifications and expression. Using methylated DNA immunoprecipitation (MeDIP) and microarray expression analysis to screen for metastasis-associated genes, we identified Iroquois homeobox 1 (IRX1). In both human osteosarcoma cell lines and clinical osteosarcoma tissues, IRX1 overexpression was strongly associated with hypomethylation of its own promoter. Furthermore, experimental modulation of IRX1 in osteosarcoma cell lines profoundly altered metastatic activity, including migration, invasion, and resistance to anoikis in vitro, and influenced lung metastasis in murine models. These prometastatic effects of IRX1 were mediated by upregulation of CXCL14/NF-κB signaling. In serum from osteosarcoma patients, the presence of IRX1 hypomethylation in circulating tumor DNA reduced lung metastasis–free survival. Together, these results identify IRX1 as a prometastatic gene, implicate IRX1 hypomethylation as a potential molecular marker for lung metastasis, and suggest that epigenetic reversion of IRX1 activation may be beneficial for controlling osteosarcoma metastasis.     

The correlation between NF-κB inhibition and disease activity by coadministration of silibinin and ursodeoxycholic acid in experimental colitis

NF‐κB is one of the most important nuclear factors responsible for overexpression of proinflammatory cytokines. This is demonstrated by increased NF‐κB activity and other dependent immune factors in inflammatory bowel disease (IBD). Anti‐inflammatory effects of silibinin and ursodeoxycholic acid (UDCA) along with their NF‐κB inhibitory property are thought to be beneficial in colitis. Trinitrobenzene sulfonic acid was used to induce colitis rat models. After instillation, 48 rats were treated with oral silibinin, UDCA alone or a combination of both. Intraperitoneal dexamethasone was used in the control group. After 12 days of treatment, colonic samples were tested for the severity of mucosal damage macroscopically and microscopically. The levels of activated NF‐κB, IL‐1β, TNF‐α, myeloperoxidase, thiobarbituric acid reactive substances (TBARS), protein carbonyl, and the antioxidant power of the bowel homogenates were determined. The results indicated a significant reduction in NF‐κB activity as well as the levels of IL‐1β, TNF‐α, TBARS, protein carbonyl, myeloperoxidase activity, and an improvement in antioxidant power of colitis in treated rats. Combination therapy resulted in a more prominent improvement in bowel antioxidant power and myeloperoxidase activity. In conclusion, combination of silibinin and UDCA by inhibition of NF‐κB and other relevant inflammatory factors of colitis is a good candidate for management of Crohn’s disease.     

Leukotriene B4 amplifies NF-κB activation in mouse macrophages by reducing SOCS1 inhibition of MyD88 expression

Activation of NF-κB and 5-lipoxygenase-mediated (5-LO-mediated) biosynthesis of the lipid mediator leukotriene B4 (LTB4) are pivotal components of host defense and inflammatory responses. However, the role of LTB4 in mediating innate immune responses elicited by specific TLR ligands and cytokines is unknown. Here we have shown that responses dependent on MyD88 (an adaptor protein that mediates signaling through all of the known TLRs, except TLR3, as well as IL-1β and IL-18) are reduced in mice lacking either 5-LO or the LTB4 receptor BTL1, and that macrophages from these mice are impaired in MyD88-dependent activation of NF-κB. This macrophage defect was associated with lower basal and inducible expression of MyD88 and reflected impaired activation of STAT1 and overexpression of the STAT1 inhibitor SOCS1. Expression of MyD88 and responsiveness to the TLR4 ligand LPS were decreased by Stat1 siRNA silencing in WT macrophages and restored by Socs1 siRNA in 5-LO-deficient macrophages. These results uncover a pivotal role in macrophages for the GPCR BLT1 in regulating activation of NF-κB through Stat1-dependent expression of MyD88.     

Positive feedback between NF-κB and TNF-α promotes leukemia-initiating cell capacity

Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy that originates from leukemia-initiating cells (LICs). The identification of common mechanisms underlying LIC development will be important in establishing broadly effective therapeutics for AML. Constitutive NF-κB pathway activation has been reported in different types of AML; however, the mechanism of NF-κB activation and its importance in leukemia progression are poorly understood. Here, we analyzed myeloid leukemia mouse models to assess NF-κB activity in AML LICs. We found that LICs, but not normal hematopoietic stem cells or non-LIC fractions within leukemia cells, exhibited constitutive NF-κB activity. This activity was maintained through autocrine TNF-α secretion, which formed an NF-κB/TNF-α positive feedback loop. LICs had increased levels of active proteasome machinery, which promoted the degradation of IκBα and further supported NF-κB activity. Pharmacological inhibition of the proteasome complex markedly suppressed leukemia progression in vivo. Conversely, enhanced activation of NF-κB signaling expanded LIC frequency within leukemia cell populations. We also demonstrated a strong correlation between NF-κB activity and TNF-α secretion in human AML samples. Our findings indicate that NF-κB/TNF-α signaling in LICs contributes to leukemia progression and provide a widely applicable approach for targeting LICs.     

Carboxyamidotriazole ameliorates experimental colitis by inhibition of cytokine production, nuclear factor-κB activation, and colonic fibrosis

Carboxyamidotrizole (CAI) has been reported to suppress the production of tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β and be effective in rats with adjuvant arthritis. The aim of this study was to investigate the role of CAI in inflammatory bowel disease (IBD). We assessed the effect of CAI in dextran sodium sulfate-induced colitis. Inflammation was scored histologically, and potential mediators of IBD were assessed by immunohistochemical and molecular biochemical approaches. CAI-treated colitis animals revealed much fewer signs of colitis with significantly decreased macroscopic and microscopic scores than vehicle-treated animals. CAI inhibited the production of TNF-α, IL-1β, and IL-6 in serum, supernatant of peritoneal macrophages, and lamina propria. CAI also decreased the expression of intercellular adhesion molecule-1 in colonic tissues. Furthermore, CAI prevented nuclear factor-κB (NF-κB) activation and inhibitor of nuclear factor-κBα phosphorylation and degradation. In addition, CAI showed a beneficial effect on colonic fibrosis, possibly by reducing the production of the fibrogenic cytokine transforming growth factor-β. The results support that CAI administration is effective in ameliorating experimental colitis and preventing colonic fibrosis. The inhibition of proinflammatory cytokines and adhesion molecules and suppression of NF-κB activation seem to contribute to this effect.     

CCN1 induces hepatic ductular reaction through integrin αvβ5–mediated activation of NF-κB

Liver cholestatic diseases, which stem from diverse etiologies, result in liver toxicity and fibrosis and may progress to cirrhosis and liver failure. We show that CCN1 (also known as CYR61), a matricellular protein that dampens and resolves liver fibrosis, also mediates cholangiocyte proliferation and ductular reaction, which are repair responses to cholestatic injury. In cholangiocytes, CCN1 activated NF-κB through integrin α_vβ₅/α_vβ₃, leading to Jag1 expression, JAG1/NOTCH signaling, and cholangiocyte proliferation. CCN1 also induced Jag1 expression in hepatic stellate cells, whereupon they interacted with hepatic progenitor cells to promote their differentiation into cholangiocytes. Administration of CCN1 protein or soluble JAG1 induced cholangiocyte proliferation in mice, which was blocked by inhibitors of NF-κB or NOTCH signaling. Knock-in mice expressing a CCN1 mutant that is unable to bind α_vβ₅/α_vβ₃ were impaired in ductular reaction, leading to massive hepatic necrosis and mortality after bile duct ligation (BDL), whereas treatment of these mice with soluble JAG1 rescued ductular reaction and reduced hepatic necrosis and mortality. Blockade of integrin α_vβ₅/α_vβ₃, NF-κB, or NOTCH signaling in WT mice also resulted in defective ductular reaction after BDL. These findings demonstrate that CCN1 induces cholangiocyte proliferation and ductular reaction and identify CCN1/α_vβ₅/NF-κB/JAG1 as a critical axis for biliary injury repair.     

Paeoniflorin suppress NF-κB activation through modulation of IκBα and enhances 5-fluorouracil-induced apoptosis in human gastric carcinoma cells

Objective

We sought to determine whether paeoniflorin enhances 5-fluorouracil-induced apoptosis in human gastric carcinoma cells, and, if so, to determine the relationship between this apoptosis and NF-κB activation.

Methods

Paeoniflorin was diluted to different concentrations and added to gastric carcinoma cells (SGC-7901) at different times. Western blot was used to test the expression of NF-κB in nuclear and IκBα, p-IκBα, IKKα in cytoplasm. Further, the intranuclear expression of NF-κB was confirmed by ELISA assay. The impact of paeoniflorin and 5-fluorouracil on cell apoptosis of gastric carcinoma cells was estimated by flow cytometry.

Results

Paeoniflorin revealed dramatic inhibition of NF-κB activity in the nuclei of the cells. The inhibition pattern of NF-κB was exhibited in a time- and dose-dependent manner, which was confirmed by Western blot and ELISA. Decreased nuclear translocation of NF-κB induced by paeoniflorin was found by preventing IκBα phosphorylation. Moreover, 5-fluorouracil-induced cell apoptosis was promoted by paeoniflorin in gastric carcinoma cells.

Conclusions

Paeoniflorin can inhibit NF-κB activity of SGC-7901 cells, and enhance 5-fluorouracil-induced apoptosis of gastric carcinoma cells.     

尿毒清颗粒对糖尿病大鼠NF-κB、NOS及VEGF的影响

目的:探讨织核因子-κB(NF-κB)、NOS和血管内皮细胞生长因子(VEGF)在糖尿病大鼠肾脏损伤中的作用以及尿毒清颗粒对其的影响。方法:链脲佐菌素诱导SD糖尿病大鼠,分为3组:正常对照组(N组)、糖尿病未干预组(D组)、尿毒清颗粒治疗组[Q组,2.6g/(kg·d)灌胃],第4、8周末检测血、尿肌酐、尿白蛋白,计算肌酐清除率(Ccr)、尿白蛋白排泄率(UAER);光镜、电镜观察肾组织病理改变;免疫组化观察肾组NF-κB、诱导型NOS(iNOS)、内皮型NOS(eNOS)、VEGF;Realtime-PCR检测肾皮质iNOS、eNOS mRNA。结果:尿毒清颗粒可以提高糖尿病大鼠Ccr(P<0.01),降低UAER(P<0.01),改善肾脏病理损伤,减少NF-κB、iNOS、eNOS和VEGF表达。结论:NF-κB、iNOS、eNOS、VEGF可能参与糖尿病肾病内皮细胞功能损伤,尿毒清颗粒抑制其表达,一定程度上对内皮损伤起到保护作用。     

Kallistatin,a novel anti-angiogenesis agent,inhibits angiogenesis via inhibition of the NF-κB signaling pathway

Development of a novel angiogenesis inhibitor will be essential for the improvement of therapeutics against cancer. Kallistatin had been recognized as an endogenous angiogenesis inhibitor. Here, we demonstrated kallistatin's strong anti-angiogenesis and anti-metastasis activity stimulated by breast cancer cells (MCF-7) and its mechanism of action in vitro. The anti-angiogenesis effect in vivo was evaluated by chicken chorioallantoic membrane (CAM) neovascularisation. Because of the underlying molecular mechanism of its anti-angiogenesis activity remains poorly understood. In this study, we examined whether the NF-κB signaling pathway was involved in the anti-angiogenesis and anti-metastasis activity of kallistatin. Kallistatin significantly inhibited TNF-α-induced nuclear factor-κB activation in a dose-dependent manner. Addition of kallistatin inhibited TNF-α induced IκBα degradation; phosphorylation of IκBα kinase (IKK), nuclear factor-κB-p65 protein; and nuclear translocation of p65/50. Meanwhile, we investigated the effects of kallistatin on the expression of vascular endothelial growth factor (VEGF) and other angiogenesis-related gene in human umbilical vein endothelial cells (HUVECs). We found that kallistatin decreased the expression of VEGF and some angiogenesis-related genes, which promoted angiogenesis in cancer. Taken together, we suggested that kallistatin would inhibit tumor angiogenesis via inhibition of the NF-κB signaling pathway and finally abrogate NF-κB-dependent gene expression. All the results revealed that kallistatin would have potential as a novel.     

Dimethyl fumarate induces apoptosis of hematopoietic tumor cells via inhibition of NF-κB nuclear translocation and down-regulation of Bcl-xL and XIAP

Dimethyl fumarate (DMF) is a fumaric acid ester that is used to treat psoriasis and multiple sclerosis. Recently, DMF was found to exhibit anti-tumor effects. However, the molecular mechanisms underlying these effects have not been elucidated. In this study, we investigated the mechanism of DMF-induced apoptosis in different human hematopoietic tumor cell lines. We found that DMF induced apoptosis in different human hematopoietic tumor cell lines but it did not affect the normal human B lymphocyte cell line RPMI 1788. We also observed a concurrent increase in caspase-3 activity and in the number of Annexin-V-positive cells. Furthermore, an examination of the survival signals, which are activated by apoptotic stimuli, revealed that DMF significantly inhibited nuclear factor-κB (NF-κB) p65 nuclear translocation. In addition, DMF suppressed B-cell lymphoma extra-large (Bcl-xL) and X-linked inhibitor of apoptosis (XIAP) expression whereas Bcl-2, survivin, Bcl-2-associated X protein (Bax), and Bim levels did not change. These results indicated that DMF induced apoptosis by suppressing NF-κB activation, and Bcl-xL and XIAP expression. These findings suggested that DMF might have potential as an anticancer agent that could be used in combination therapy with other anticancer drugs for the treatment of human hematopoietic tumors.     

β1-adrenoceptor stimulation promotes LPS-induced cardiomyocyte apoptosis through activating PKA and enhancing CaMKII and IκBα phosphorylation

IntroductionCaspase activation and cardiomyocyte apoptosis have been implicated in lipopolysaccharide (LPS)-induced cardiac contractile dysfunction. We have recently demonstrated that β1-adrenoceptor (AR) activation by endogenous norepinephrine contributes to cardiomyocyte apoptosis in endotoxemic mice. Here, we further investigated the molecular mechanisms for the enhancing effect of β₁-AR activation on LPS-induced cardiomyocyte apoptosis.MethodsThe adult mouse ventricular myocytes were exposed to LPS, dobutamine, protein kinase A (PKA) inhibitor or/and nifedipine, an L-type Ca²⁺ channel blocker. Male BALB/c mice were treated with LPS or/ and β₁-AR antagonist, atenolol. Cardiomyocyte apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL) assay and apoptosis-associated molecules were detected.ResultsLPS induced apoptosis in adult mouse ventricular myocytes, dobutamine (DOB), a β₁-AR agonist, promoted apoptosis, caspase-8, 9 and 3 activation and increased cytosolic Ca²⁺ concentration in LPS-challenged cardiomyocytes. DOB also up-regulated TNF-α expression, decreased Bcl-2 levels, promoted Bax translocation to mitochondria, mitochondrial membrane potential loss and cytochrome c release as well as IκBα, p38 MAPK, JNK and Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) phosphorylation in LPS-treated cardiomyocytes. PKA inhibitor abolished the effects of DOB on caspase-9 activation, Bcl-2 levels as well as JNK and p38 MAPK phosphorylation, but not on IκBα phosphorylation, TNF-α expression and caspase-8 activation in LPS-stimulated cardiomyocytes. Pretreatment with nifedipine not only significantly blocked the enhancing effects of DOB on LPS-induced elevation in cytosolic Ca²⁺ concentration and CaMKII phosphorylation in cardiomyocytes, but also partly reversed the effects of DOB on caspase-9 and caspase-3/7 activities in LPS-treated cardiomyocytes. Furthermore, atenolol suppressed TNF-α expression, JNK, p38 MAPK and CaMKII phosphorylation, increased Bcl-2 expression, and inhibited cytochrome c release and cardiomyocyte apoptosis in the myocardium of endotoxemic mice.Conclusionsβ₁-AR activation promotes LPS-induced apoptosis through activating PKA, increasing CaMKII phosphorylation as well as enhancing IκBα phosphorylation and TNF-α expression in cardiomyocytes.     

Proline-rich polypeptide complex (PRP) regulates secretion of inflammatory mediators by its effect on NF-κB activity

A proline-rich polypeptide complex (PRP) with immunoregulatory and procognitive activities shows beneficial effects in the Alzheimer's disease (AD). The mechanism of action of PRP is not yet fully clarified, we have shown that the PRP complex inhibits overproduction of reactive oxygen species, nitric oxide and proinflammatory cytokines induced by lipopolysaccharide (LPS). LPS stimulation exerts its inflammatory effects through the activation of the classical nuclear factor-κB (NF-κB) pathway. The results presented in this study showed the ability of PRP to inhibit the NF-κB activity induced by LPS while it increased activity of NF-κB in untreated cells. Examining the effect of PRP on IκB it was shown that relative level of IκB was lowered in the presence of PRP. It seems that in cells untreated with LPS, PRP can activate proteasome system and stimulate IκB degradation. Our results suggest that the regulatory effect of PRP on inflammatory processes may be associated with the influence of PRP on NF-κB translocation. Inhibitory effect of PRP on NF-κB activity might, at least in part, contribute to the beneficial therapeutic effects in the case of Alzheimer's disease.