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The aim of this study was to investigate the anti-inflammatory and hepatoprotective effects of Ganoderma lucidum polysaccharides (GLPS) on carbon tetrachloride (CCl 4 )-induced hepatocyte damage in common carp ( Cyprinus carpio L.). GLPS (0.1, 0.3, 0.6 mg/ml) were added to the primary hepatocytes before (pre-treatment), after (post-treatment) and both before and after (pre- and post-treatment) the incubation of the hepatocytes with CCl 4 at the concentration of 8 mM in the culture medium. The supernatants and cells were collected respectively to detect the biochemical indicators. The levels of TNF-α, IL-1β, caspase-3 and caspase-8 were measured by ELISA, the mRNA expressions of CYP1A and CYP3A were determined by RT-PCR, and western blotting was used to assay the relative protein expressions of c-Rel and p65. Results showed that GLPS significantly improved cell viability and inhibited the elevations of the marker enzymes (GOT, GPT, LDH) and MDA induced by CCl 4 , and markedly increased the level of SOD. Treatments with GLPS resulted in a significant decrease in the expressions of CYP1A and CYP3A, and significantly down-regulated extrinsic apoptosis and immune inflammatory response. In brief, the present study showed that GLPS can protect hepatocyte injury induced by CCl 4 through inhibiting lipid peroxidation, elevating antioxidant enzyme activity and suppressing apoptosis and immune inflammatory response. [ABSTRACT FROM AUTHOR]

Ubiquitin ligase Nrdp1 (neuregulin receptor degradation protein 1) plays important roles in multiple physiological process because it can ubiquitinate various substrates such as ErbB3, BRUCE, MyD88, C/EBPβ, and Parkin, and so forth. In addition to the physiological function, it was also found to be involved in tumor progression. It has been shown that loss of Nrdp1 enhances breast cancer cell growth. Up to now, the role of Nrdp1 in glioma has not been elucidated. Here, we reported that Nrdp1 as well as cleaved caspase 3 was lower expressed in human glioma tissues comparing with the nontumorous. And then we found that the expression of Nrdp1 and cleaved caspase 3 was increased in the treatment of Temozolomide (TMZ), a drug for glioma chemotherapy. Further investigation indicated that transient transfection of Nrdp1 significantly promoted cell apoptosis by aggravating the degradation of BRUCE and activation of caspase 3. In addition, overexpression of Nrdp1 augmented TMZ induced apoptosis by evaluating the degradation of BRUCE and the activation of caspase 3, while silencing of Nrdp1 reduced the sensitivity to the TMZ by inhibiting the degradation of BRUCE and the activation of caspase 3 in human glioma cells. These observations show that Nrdp1 is a pro-apoptotic protein in human glioma and lower expression of Nrdp1 in human glioma may promote tumor progression by reducing apoptosis, suggesting that Nrdp1 may be an important regulator in the development of human glioma. © 2014 IUBMB Life, 66(10):704-710, 2014 [ABSTRACT FROM AUTHOR]

Abstract: A brush-shaped polymer PHEMA-g-(PEI-b-PEG) with poly(2-hydroxyethyl methacrylate) (PHEMA) backbone and linear poly(ethylenimine)-b-poly(ethylene glycol) (PEI-b-PEG) side chains was synthesized and evaluated as a vector for potential cancer gene therapy. The characterizations by 1H NMR and laser light scattering demonstrated the brush structure of the polymer. PHEMA-g-(PEI-b-PEG) was much less cytotoxic when compared with branched poly(ethylenimine) with M w of 25kDa. The capacity of plasmid DNA condensation by PHEMA-g-(PEI-b-PEG) was demonstrated by gel retardation assay, and they formed nanosized complexes with surface zeta potential around 20mV at N/P ratios higher than 5:1. The complexes of PHEMA-g-(PEI-b-PEG) with plasmid DNA were more efficiently internalized by BT474 cells in comparison with the complexes of PEI25K, leading to higher gene transfection in cells. Further investigation using complexes of PHEMA-g-(PEI-b-PEG) with plasmid DNA encoding wild-type p53 gene showed its potential as a carrier for cancer gene therapy. The complexes of PHEMA-g-(PEI-b-PEG) successfully induced elevated wild-type p53 expression in BT474 cells and led to enhanced apoptosis of BT474 cells. Transfection of wild-type p53 using the complexes also significantly increased the sensitivity of BT474 cells to doxorubicin chemotherapy, suggesting the potential of this carrier in cancer gene therapy. [Copyright &y& Elsevier]

Germacrone (GM) displays a wide range of antitumor, antioxidant and anti-inflammatory effects; however, to the best of our knowledge, the effects of GM on lung cancer cell apoptosis and cell cycle arrest have not been previously reported. The aim of the present study was to investigate discussed the effects of GM on the apoptosis and cycle arrest of lung cancer cells. Cell viability, proliferation and apoptosis were assessed by performing Cell Counting Kit-8, colony formation and TUNEL assays, respectively. Western blotting was performed to detect the expression levels of apoptosis-, cell cycle- and Akt/MDM2 proto-oncogene (MDM2)/p53 signaling pathway-related proteins. Compared with the control group, 50, 100 and 200 µM GM significantly inhibited lung cancer cell proliferation, but significantly induced cell apoptosis and G1/S cell cycle arrest. GM also significantly altered the expression levels of Akt/MDM2/p53 signaling pathway-related proteins compared with the control group. Administration of Akt activator SC79 significantly reversed GM-mediated antiproliferative, proapoptotic and pro-cell cycle arrest effects in lung cancer cells. Therefore, the results of the present study demonstrated that GM induced lung cancer cell apoptosis and cell cycle arrest via the Akt/MDM2/p53 signaling pathway. [ABSTRACT FROM AUTHOR]

Fatty liver injury (or disease) is a common disease in farmed fish, but its pathogenic mechanism is not fully understood. Therefore the present study aims to investigate high-fat diet (HFD)-induced liver injury and explore the underlying mechanism in fish. The tilapia were fed on control diet and HFD for 90 days, and then the blood and liver tissues were collected to determine biochemical parameter, gene expression and protein level. The results showed that HFD feeding signally increased the levels of plasma aminotransferases and pro-inflammatory factors after 60 days. In liver and plasma, HFD feeding significantly suppressed antioxidant ability, but enhanced lipid peroxidation formation, protein oxidation and DNA damage after 60 or 90 days. Further, the Nrf2 pathway and antioxidative function-related genes were adversely changed in liver of HFD-fed tilapia after 60 and/or 90 days. Meanwhile, HFD treatment induced apoptosis via initiating mitochondrial pathway in liver after 90 days. Furthermore, after 90 days of feeding, the expression of genes or proteins related to JNK pathway and TLRs-Myd88-NF-κB pathway was clearly upregulated in HFD treatment. Similarly, the mRNA levels of inflammatory factors including tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), IL-6, IL-8 and IL-10 were also upregulated in liver of HFD-fed tilapia after 60 and/or 90 days. In conclusion, the current study suggested that HFD feeding impaired antioxidant defense system, induced apoptosis, enhanced inflammation and led to liver injury. The adverse influences of HFD in the liver might be due to the variation of Nrf2, JNK and TLRs-Myd88-NF-κB signaling pathways. • HFD feeding impairs Nrf2 pathway to weaken antioxidant defense system in liver of tilapia. • HFD feeding induces apoptosis via mitochondrial pathway. • HFD feeding activates JNK-NF-κB pathway and TLRs-MyD88-NF-κB pathway to mediate inflammatory response. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is one of the malignant tumors with high incidence and mortality rates in the world. Isothiocyanates (ITCs), bioactive substances present primarily in the plant order Brassicales, have been proved to be promising candidates for novel anti-HCC drugs with chemopreventive and anticancer activities. Iberverin, a predominant ITC isolated from the seeds of oxheart cabbage, has been discovered with anticancer property in lung cancer cells. However, the roles of iberverin in HCC remain elusive. In the present study, the effect and potential mechanisms of iberverin against human HCC were dissected. We demonstrated that low concentrations of iberverin inhibited cell proliferation, suppressed migration and induced mitochondrial-related apoptosis in vitro, and hampered tumorigenicity in vivo, with no obvious toxicity. Furthermore, we found that iberverin treatment induced DNA damage and G2/ M phase arrest. Iberverin treatment also caused increased intracellular reactive oxygen species formation and glutathione depletion. Taken together, these results suggest that iberverin promotes mitochondrial-mediated apoptosis and induces DNA damage and G2/M cell cycle arrest in HCC by enhancing oxidative stress. Our findings provide better understanding of the anti-HCC mechanisms of ITCs and the potential for the natural product iberverin as a promising new anti-HCC biotherapeutic. [ABSTRACT FROM AUTHOR]

As a neurological disease with high morbidity, disability, and mortality, the pathological mechanism underlying stroke involves complex processes such as neuroinflammation, oxidative stress, apoptosis, autophagy, and excitotoxicity; but the related research on these molecular mechanisms has not been effectively applied in clinical practice. As a form of iron-dependent regulated cell death, ferroptosis was first discovered in the pathological process of cancer, but recent studies have shown that ferroptosis is closely related to the onset and development of stroke. Therefore, a deeper understanding of the relationship between ferroptosis and stroke may lead to more effective treatment strategies. Herein, we reviewed the mechanism(s) underlying the onset of ferroptosis in stroke, the potential role of ferroptosis in stroke, and the crosstalk between ferroptosis and other pathological mechanisms. This will further deepen our understanding of ferroptosis and provide new approaches to the treatment of stroke. [ABSTRACT FROM AUTHOR]

Highlights: [•] We explored the underlying toxicology of CCl4 at the cellular and molecular levels. [•] QRT-PCR detected the gene expression of NF-κB and inflammatory cytokines. [•] The apoptosis and necrosis occurred simultaneously in carp liver damage. [•] CCl4 activated the TNF-α/NF-κB and TRL4/NF-κB signaling pathways. [Copyright &y& Elsevier]

Highlights: [•] GCRV induced apoptosis in CIK cells. [•] Activation of apoptosis was dependent on caspase pathway. [•] The oxidative damage induced by GCRV was mostly related to the virus replication. [Copyright &y& Elsevier]

Background: Theabrownin (TB) is a bioactive component of tea and has been reported to exert effects against many human cancers, but its efficacy and mechanism on hepatocellular carcinoma (HCC) with different p53 genotypes remains unclarified. Methods: MTT assay, DAPI staining, flow cytometry and SA-β-gal staining were applied to evaluate the effects of TB on HCC cells. Quantitative real time PCR (qPCR) and Western blot (WB) were conducted to explore the molecular mechanism of TB. A xenograft model of zebrafish was established to evaluate the anti-tumor effect of TB. Results: MTT assays showed that TB significantly inhibited the proliferation of SK-Hep-1, HepG2, and Huh7 cells in a dose-dependent manner, of which SK-Hep-1 was the most sensitive one with the lowest IC50 values. The animal data showed that TB remarkably suppressed SK-Hep-1 tumor growth in xenograft model of zebrafish. The cellular data showed TB's pro-apoptotic and pro-senescent effect on SK-Hep-1 cells. The molecular results revealed the mechanism of TB that p53 signaling pathway (p-ATM, p-ATR, γ-H2AX, p-Chk2, and p-p53) was activated with up-regulation of downstream senescent genes (P16, P21, IL-6 and IL-8) as well as apoptotic genes (Bim, Bax and PUMA) and proteins (Bax, c-Casp9 and c-PARP). The p53-mediated mechanism was verified by using p53-siRNA. Moreover, by using JNK-siRNA, we found JNK as a bypass regulator in TB's mechanism. Conclusions: To sum up, TB exerted tumor-inhibitory, pro-senescent and pro-apoptotic effects on SK-Hep-1 cells through ATM-Chk2-p53 signaling axis in accompany with JNK bypass regulation. This is the first report on the pro-senescent effect and multi-target (p53 and JNK) mechanism of TB on HCC cells, providing new insights into the underlying mechanisms of TB's anti-HCC efficacy. [ABSTRACT FROM AUTHOR]

Reovirus infection induces dramatic changes in host mRNA expression. We utilized oligonucleotide microarrays to measure cellular mRNA decay rates in mock- or reovirus-infected murine L929 cells to determine if changes in host mRNA expression are a consequence of reovirus-induced alterations in cellular mRNA stability. Our analysis detected a subset of cellular transcripts that were coordinately induced and stabilized following infection with the reovirus isolates c87 and c8, strains that led to an inhibition of cellular translation, but not following infection with Dearing, a reovirus isolate that did not negatively impact cellular translation. The induced and stabilized transcripts encode multiple regulators of TGF- β signaling, including components of the Smad signaling network and apoptosis/survival pathways. The coordinate induction, through mRNA stabilization, of multiple genes that encode components of TGF-β signaling pathways represents a novel mechanism by which the host cell responds to reovirus infection. [ABSTRACT FROM AUTHOR]

Growth arrest and DNA damage‑inducible‑β (Gadd45β) is a stress‑response protein involved in a number of processes, including cell cycle control, DNA repair, survival and death control, and stress signaling, depending on its interactions. Gadd45β expression is dysregulated in numerous types of cancer, functioning as either a tumor promoter or a tumor suppressor. However, the functions of Gadd45β in cholangiocarcinoma (CCA), particularly in metastasis, has not been studied. The immunohistochemical analysis of Gadd45β expression revealed that 75% of histological specimens from patients with CCA expressed high levels of Gadd45β, and that high Gadd45β expression was associated with metastasis. The role of Gadd45β in CCA was examined using siRNA‑mediated gene knockdown in HuCCA‑1, a human CCA cell line established from a Thai patient. The effects of Gadd45β downregulation upon cell viability and death, invasion, migration, matrix metalloproteinase (MMP) activity and epithelial‑mesenchymal transition (EMT) marker expression were investigated. Gadd45β knockdown impaired cell viability, which was associated with the induction of apoptosis. In addition, there was a marked reduction in invasion and migration, although MMP activity was unaffected. Impairment of these metastatic properties was accompanied by the decreased expression of EMT markers, including Slug, vimentin, claudin‑1 and zona occludens protein 1, whereas E‑cadherin expression was increased. The present study suggests that Gadd45β is involved in regulating the viability and the metastatic potential of CCA cells, which may be mediated by the modulation of the EMT pathway. [ABSTRACT FROM AUTHOR]

Purpose: The mammalian peroxiredoxin (PRX) family contains six members that provide antioxidant defense in different cell types by removing reactive oxygen species (ROS) through conserved active cysteines. Different from other members, PRX3 is predominantly located in mitochondria, a major apoptosis mediator. The purpose of this review is to summarize the findings on PRX3 concerning its role in ROS removal, apoptosis, and chemoresistance of cancer cells. Methods: The relevant literature from PubMed and Medline databases is reviewed in this article (1994-2014). Results: Because of fast growth and relatively low supply of oxygen in cancer cells, ROS production from mitochondria is exaggerated to an extent that overwhelms cellular antioxidant defenses resulting in oxidative stress. As an active responder to oxidative stress, PRX3 is accordingly up-regulated in cancer cells to remove cellular ROS and inhibit apoptosis, which provides a favorable microenvironment for cell proliferation. Conclusion: Since most of chemotherapy or radiotherapy for cancers is through ROS increase and apoptotic induction, PRX3 might be involved in the chemotherapeutic resistance of cancers. [ABSTRACT FROM AUTHOR]

There are controversies about the mechanism of myocardium apoptosis in hypertensive heart disease. The aim of this study was to investigate the relationship among autophagy, Cx43 and apoptosis in aged spontaneously hypertensive rats ( SHRs) and establish whether Aliskiren is effective or not for the treatment of myocardium apoptosis. Twenty-one SHRs aged 52 weeks were randomly divided into three groups, the first two receiving Aliskiren at a dose of 10 and 25 mg/kg/day respectively; the third, placebo for comparison with seven Wistar- Kyoto ( WKY) as controls. After a 2-month treatment, systolic blood pressure ( SBP), heart to bw ratios ( HW/ BW%) and angiotensin II (AngII) concentration were significantly enhanced in SHRs respectively. Apoptotic cardiomyocytes detected with TUNEL and immunofluorescent labelling for active caspase-3 increased nearly fourfolds in SHRs, with a decline in the expression of survivin and AKT activation, and an increase in caspase-3 activation and the ratio of Bax/Bcl-2. Myocardium autophagy, detected with immunofluorescent labelling for LC3-II, increased nearly threefolds in SHRs, with the up-regulation of Atg5, Atg16L1, Beclin-1 and LC3-II. The expression of Cx43 plaque was found to be down-regulated in SHRs. Aliskiren significantly reduced SBP, HW/ BW%, AngII concentration and the expression of AT1R. Thus, Aliskiren protects myocardium against apoptosis by decreasing autophagy, up-regulating Cx43. These effects showed a dose-dependent tendency, but no significance. In conclusion, the myocardium apoptosis developed during the hypertensive end-stage of SHRs could be ameliorated by Aliskiren via the regulation of myocardium autophagy and maladaptive remodelling of Cx43. [ABSTRACT FROM AUTHOR]

A hallmark of cancer is resistance to apoptosis, with both the loss of proapoptotic signals and the gain of anti-apoptotic mechanisms contributing to tumorigenesis. As inducing apoptosis in malignant cells is one of the most challenging tasks regarding cancer, researchers increasingly focus on natural products to regulate apoptotic signaling pathways. Curcumin, a polyphenolic derivative of turmeric, is a natural compound derived from Curcuma longa, has attracted great interest in the research of cancer during the last half century. Extensive studies revealed that curcumin has chemopreventive properties, which are mainly due to its ability to arrest cell cycle and to induce apoptosis in cancer cells either alone or in combination with chemotherapeutic agents or radiation. The underlying action mechanisms of curcumin are diverse and has not been elucidated so far. By regulating multiple important cellular signalling pathways including NF-κB, TRAIL, PI3 K/Akt, JAK/STAT, Notch-1, JNK, etc., curcumin are known to activate cell death signals and induce apoptosis in pre-cancerous or cancer cells without affecting normal cells, thereby inhibiting tumor progression. Several phase I and phase II clinical trials indicate that curcumin is quite safe and may exhibit therapeutic efficacy. This article reviews the main effects of curcumin on the different apoptotic signaling pathways involved in curcumin induced apoptosis in cancer cells via cellular transduction pathways and provides an in depth assessment of its pharmacological activity in the management of tumor progression. [ABSTRACT FROM AUTHOR]

Eosinophils play a central role in asthma. The present study was performed to investigate the effect of tumour necrosis factor-α (TNF-α) on longevity of isolated human eosinophils. In contrast to Fas, TNF-α inhibited eosinophil apoptosis as evidenced by a combination of flow cytometry, DNA fragmentation assay and morphological analyses. The effect of TNF-α on eosinophil apoptosis was reversed by a TNF-α neutralising antibody. The anti-apoptotic effect of TNF-α was not due to autocrine release of known survival-prolonging cytokines interleukins 3 and 5 or granulocyte-macrophage-colony-stimulating factor as their neutralisation did not affect the effect of TNF-α. The anti-apoptotic signal was mediated mainly by the TNF-receptor 1. TNF-α induced phosphorylation and degradation of IκB and an increase in NF-κB DNA-binding activity. The survival-prolonging effect of TNF-α was reversed by inhibitors of NF-κB pyrrolidinedithiocarbamate and gliotoxin and by an inhibitor of IκB kinase, BMS-345541. TNF-α induced also an increase in AP-1 DNA-binding activity and the antiapoptotic effect of TNF-α was potentiated by inhibitors of AP-1, SR 11302 and tanshinone IIA and by an inhibitor of c-jun-N-terminal kinase, SP600125, which is an upstream kinase activating AP-1. Our results thus suggest that TNF-α delays human eosinophil apoptosis via TNF-receptor 1 and the resulting changes in longevity depend on yin-yang balance between activation of NF-κB and AP-1. [ABSTRACT FROM AUTHOR]

Death receptor-mediated hepatocyte apoptosis is implicated in a wide range of liver diseases including viral and alcoholic hepatitis, ischemia/reperfusion injury, fulminant hepatic failure, cholestatic liver injury, as well as cancer. Deletion of NF-κB essential modulator in hepatocytes (IKKγ/Nemo) causes spontaneous progression of TNF-mediated chronic hepatitis to hepatocellular carcinoma (HCC). Thus, we analyzed the role of death receptors including TNFR1 and TRAIL in the regulation of cell death and the progression of liver injury in IKKγ/Nemo-deleted livers. We crossed hepatocyte-specific IKKγ/Nemo knockout mice (NemoΔhepa) with constitutive TNFR1−/− and TRAIL−/− mice. Deletion of TNFR1, but not TRAIL, decreased apoptotic cell death, compensatory proliferation, liver fibrogenesis, infiltration of immune cells as well as pro-inflammatory cytokines, and indicators of tumor growth during the progression of chronic liver injury. These events were associated with diminished JNK activation. In contrast, deletion of TNFR1 in bone-marrow-derived cells promoted chronic liver injury. Our data demonstrate that TNF- and not TRAIL signaling determines the progression of IKKγ/Nemo-dependent chronic hepatitis. Additionally, we show that TNFR1 in hepatocytes and immune cells have different roles in chronic liver injury-a finding that has direct implications for treating chronic liver disease. [ABSTRACT FROM AUTHOR]

Pheochromocytomas (PHEOs) and paragangliomas (PGLs) are specific types of neuroendocrine tumors that originate in the adrenal medulla or sympathetic/parasympathetic paraganglia, respectively. Although these tumors are intensively studied, a very effective treatment for metastatic PHEO or PGL has not yet been established. Preclinical evaluations of novel therapies for these tumors are very much required. Therefore, in this study we tested the effect of triptolide (TTL), a potent nuclear factor-kappaB (NF-κB) inhibitor, on the cell membrane norepinephrine transporter (NET) system, considered to be the gatekeeper for the radiotherapeutic agent 131I-metaiodobenzylguanidine (131I-MIBG). We measured changes in the mRNA and protein levels of NET and correlated them with proapoptotic factors and metastasis inhibition. The study was performed on three different stable PHEO cell lines. We found that blocking NF-κB with TTL or capsaicin increased both NET mRNA and protein levels. Involvement of NF-κB in the upregulation of NET was verified by mRNA silencing of this site and also by using NF-κB antipeptide. Moreover, in vivo treatment with TTL significantly reduced metastatic burden in an animal model of metastatic PHEO. The present study for the first time shows how NF-κB inhibitors could be successfully used in the treatment of metastatic PHEO/PGL by a significant upregulation of NET to increase the efficacy of 131I-MIBG and by the induction of apoptosis. [ABSTRACT FROM AUTHOR]

The ribosomal protein S27 (metallopanstimulin-1, MPS-1) has been reported to be a multifunctional protein, with increased expression in a number of cancers. We reported previously that MPS-1 was highly expressed in human gastric cancer. Knockdown of MPS-1 led to spontaneous apoptosis and repressed proliferation of human gastric cancer cells in vitro and in vivo. However, how does MPS-1 regulate these processes is unclear. Here we performed microarray and pathway analyses to investigate possible pathways involved in MPS-1 knockdown-induced apoptosis in gastric cancer cells. Our results showed that knockdown of MPS-1 inhibited NF-κB activity by reducing phosphorylation of p65 at Ser536 and IκBα at Ser32, inhibiting NF-κB nuclear translocation, and down-regulating its DNA binding activity. Furthermore, data-mining the Gene-Regulatory-Network revealed that growth arrest DNA damage inducible gene 45β ( Gadd45β), a direct NF-κB target gene, played a critical role in MPS-1 knockdown-induced apoptosis. Over-expression of Gadd45β inhibited MPS-1 knockdown-induced apoptosis via inhibition of JNK phosphorylation. Taken together, these data revealed a novel pathway, the MPS-1/NF-κB/Gadd45β signal pathway, played an important role in MPS-1 knockdown-induced apoptosis of gastric cancer cells. This study sheds new light on the role of MPS-1/NF-κB in apoptosis and the possible use of MPS-1 targeting strategy in the treatment of gastric cancer. [ABSTRACT FROM AUTHOR]

Meningococcal invasive isolates of the ST-11 clonal complex are most frequently associated with disease and rarely found in carriers. Unlike carriage isolates, invasive isolates induce apoptosis in epithelial cells through the TNF-α signaling pathway. While invasive and non-invasive isolates are both able to trigger the TLR4/MyD88 pathway in lipooligosaccharide (LOS)- dependant manner, we show that only non-invasive isolates were able to induce sustained NF-κB activity in infected epithelial cells. ST-11 invasive isolates initially triggered a strong NF-κB activity in infected epithelial cells that was abolished after 9h of infection and was associated with sustained activation of JNK, increased levels of membrane TNFR1, and induction of apoptosis. In contrast, infection with carriage isolates lead to prolonged activation of NF-κB that was associated with a transient activation of JNK increased TACE/ADAM17-mediated shedding of TNFR1 and protection against apoptosis. Our data provide insights to understand the meningococcal duality between invasiveness and asymptomatic carriage. [ABSTRACT FROM AUTHOR]

The flap endonuclease-1 ( FEN-1) gene is involved in DNA replication and repair, and it maintains genomic stability as well as the accuracy of DNA replication under normal growth conditions. However, FEN-1 also plays an important role in apoptosis and cancer development. We cloned the BmFEN-1 gene from Bombyx mori, which was 1343 bp in length and possessed an 1143 bp ORF (123-1266). It consists of seven introns and eight exons that encode a protein with 380 amino acids that has the typical XPG domain. The N-terminal motif is located at amino acids 95-105, and the proliferating cell nuclear antigen interaction motif is located at amino acids 337-344. RNA interference-mediated reduction of BmFEN-1 expression induced cell cycle arrest in S phase in BmE-SWU1 cells. These results suggest that BmFEN-1 can inhibit apoptosis and promote cell proliferation. [ABSTRACT FROM AUTHOR]

Background: Abrogation of apoptosis for prolonged cell survival is essential in cancer progression. In our previous studies, we showed the MMP-2 downregulation induced apoptosis in cancer cell lines. Here, we attempt to investigate the exact molecular mechanism of how MMP-2 depletion leads to apoptosis in glioma xenograft cell lines. Methodology/Principal Findings: MMP-2 transcriptional suppression by MMP-2siRNA (pM) induces apoptosis associated with PARP, caspase-8 and -3 cleavage in human glioma xenograft cells 4910 and 5310. Western blotting and cytokine array showed significant decrease in the cellular and secreted levels of TNF-α with concomitant reduction in TNFR1, TRADD, TRAF2, RIP, IKKβ and pIκBα expression levels resulting in inhibition of p65 phosphorylation and nuclear translocation in pM-treated cells when compared to mock and pSV controls. In addition MMP-2 suppression led to elevated Fas-L, Fas and FADD expression levels along with increased p38 and JNK phosphorylation. The JNK-activity assay showed prolonged JNK activation in pM-transfected cells. Specific inhibition of p38 with SB203580 did not show any effect whereas inhibition of JNK phosphorylation with SP600125 notably reversed pM-induced cleavage of PARP, caspase-8 and -3, demonstrating a significant role of JNK in pM-induced cell death. Supplementation of rhMMP-2 counteracted the effect of pM by remarkably elevating TNF-α, TRADD, IKKβ and pIκBα expression and decreasing FADD, Fas-L, and phospho-JNK levels. The EMSA analysis indicated significant reversal of pM-inhibited NF-κB activity by rhMMP-2 treatment which rescued cells from pM-induced cell death. In vivo studies indicated that pM treatment diminished intracranial tumor growth and the immuno histochemical analysis showed decreased phospho-p65 and enhanced phospho-JNK levels that correlated with increased TUNEL-positive apoptotic cells in pM-treated tumor sections. Conclusion/Significance: In summary, our study implies a role of MMP-2 in the regulation of TNF-α mediated constitutive NF-κB activation and Fas-mediated JNK mediated apoptosis in glioma xenograft cells in vitro and in vivo. [ABSTRACT FROM AUTHOR]

The zinc-finger protein A20 has crucial physiological functions as a dual inhibitor of nuclear factor-κB (NF-κB) activation and apoptosis in tumor necrosis factor (TNF) receptor 1 signaling pathway. Although the molecular basis for the anti-NF-κB function of A20 has been well elucidated, the anti-apoptotic function of A20 is largely unknown. Here, we report a novel mechanism underlying the anti-apoptotic function of A20: A20 blocks TNF-induced apoptosis through suppression of c-jun N-terminal kinase (JNK) by targeting apoptosis signal-regulating kinase1 (ASK1). First, the ectopic expression of A20 drastically inhibits TNF-induced JNK activation and apoptosis in multiple cell types including those deficient of NF-κB activation. Unexpectedly, the blunting effect of A20 on TNF-induced JNK activation is not mediated by affecting the TNFR1 signaling complex formation. Instead, A20 interacts with ASK1, an important MAPKK kinase in the JNK signaling cascade. More importantly, overexpression of wild-type A20, but not of mutant A20 (ZnF4; C624A, C627A), promotes degradation of the ASK1 through the ubiquitin-proteasome system. Taken together, the results from this study reveal a novel anti-apoptotic mechanism of A20 in TNF signaling pathway: A20 binds to ASK1 and mediates ASK1 degradation, leading to suppression of JNK activation and eventually blockage of apoptosis. [ABSTRACT FROM AUTHOR]

Liver diseases represent an important cause of morbidity and mortality in the world. Death of hepatocytes and other hepatic cell types is a characteristic feature of several forms of liver injury such as cholestasis, viral hepatitis, drug- or toxin-induced injury, and alcohol-induced liver damage. Moreover, irrespectively of the reason, liver injury seems to be facilitated by similar immune effector mechanisms common to these various liver diseases. Indeed, common immune effector mechanisms may explain the high prevalence of cirrhosis and cancer development in most forms of liver disease. Improved understanding of the immune cell-mediated mechanisms involved in hepatocyte cell death could be beneficial for the development of common therapeutic strategies against different forms of liver diseases. In this review, we will discuss novel findings on the role of different immune cells in liver disease and immune cell-induced death executioner mechanisms involved in hepatocyte cell death. [ABSTRACT FROM AUTHOR]

Nuclear factor kappa enhancer binding protein (NF-KB) regulates diverse biological processes including immunity, inflammation, and apoptosis. A vast array of cellular stimuli converges on NF-KB, and ubiquitination plays an essential role in the coordination of these signals to regulate NF-κB activity. At least three steps in NF-κB activation directly involve ubiquitination: proteasomal degradation of inhibitor of NF-κB (IκB), processing of NF-κB precursors, and activation of the transforming growth factor (TGF)-β-activated kinase (TAK1) and IκB kinase (IKK) complexes. In this review, we discuss recent advances in the identification and characterization of ubiquitination and deubiquitination machinery that regulate NF-κB. Particular emphasis is given to proteasome-independent functions of ubiquitin, specifically its role in the activation of protein kinase complexes and in coordination of cell survival and apoptosis signals downstream of minor necrosis factor α (TNFα). [ABSTRACT FROM AUTHOR]

Several diseases are characterized by chronic inflammation, a condition frequently associated with angiogenesis and fibrogenesis that account for the development of granulation tissue. Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB) is a crucial modulator of intracellular prosurvival signaling pathways and is implicated in the pathogenesis of inflammatory process. In this study, we have investigated the role of NF-κB in the angiogenic and fibrogenic response induced by λ-carrageenin in a rat model of chronic inflammation at 1, 3, and 5 days. The subcutaneous implant of λ-carrageenin-soaked sponges in rat induced a time-related increase of granulation tissue formation accompanied by intense neovascularization. These λ-carrageenin-induced changes were significantly reduced by coinjection of wild-type oligodeoxynucleotide (WT ODN) decoy to NF-κB. Molecular, morphological, and ultrastructural analysis performed on whole granulation tissue demonstrated: (1) inhibition of NF-κB/DNA binding activity; (2) downregulation of cyclooxygenase-2, matrix metalloproteinase-9, tumor necrosis factor-α, and vascular endothelial growth factor; (3) upregulation of thrombospondin (TSP)-1 at 1 day and TSP-2 at 5 days; and (4) increase in Bax to Bcl-2 ratio. Our findings show that the blockade of NF-κB activation by WT ODN decoy prevents the development of granulation tissue induced by λ-carrageenin-soaked sponge implant upregulating Bax as well as TSP-1 and TSP-2 expression. [ABSTRACT FROM AUTHOR]

Vesicular stomatitis virus (VSV) matrix (M) protein can directly induce apoptosis by inhibiting host gene expression when it is expressed in the absence of other viral components. Previously, we found that the M protein gene complexed to DOTAP-cholesterol liposome (Lip-MP) can suppress malignant tumor growth in vitro and in vivo; however, little is known regarding the biological effect of Lip-MP combined with radiation. The present study was designed to determine whether Lip-MP could enhance the antitumor activity of radiation . LLC cells treated with a combination of Lip-MP and radiation displayed apparently increased apoptosis compared with those treated with Lip-MP or radiation alone. Mice bearing LLC or Meth A tumors were treated with intratumoral or intravenous injections of Lip-MP and radiation. The combined treatment significantly reduced mean tumor volumes compared with either treatment alone in both tumor models and prolonged the survival time in Meth A tumor models and the intravenous injection group of LLC tumor models. Moreover, the antitumor effects of Lip-MP combined with radiation were greater than their additive effects when compared with the expected effects of the combined treatment in vivo. This study suggests that Lip-MP enhanced the antitumor activity of radiation by increasing the induction of apoptosis. [ABSTRACT FROM AUTHOR]

When administrated by isolated limb perfusion, tumor necrosis factor α (TNFα) is an efficient antitumor agent that improves drug penetration and destroys angiogenic vessels. Moreover, the pronounced potentiation of TNFα-induced apoptosis by NF-κB inhibitors suggest that these compounds could enhance TNFα antitumor efficacy through direct induction of tumor cell apoptosis. Therefore, attempts at amplifying signaling pathways that mediate TNFα antitumor effects could help to design combination therapies improving its efficiency. We report that nanomolar concentrations of all-trans retinoic acid (ATRA) amplify TNFα-induced apoptosis in APL cells expressing a specific repressor of NF-κB activation. This effect is abolished by the pan-caspase inhibitor, Z-VAD-fmk and by caspase-8 and -9 inhibitors. Cell death is accompanied by a drop of mitochondrial potential and by poly (ADP-ribose) polymerase (PARP) activation. Using specific PARP-1 inhibitors and siRNAs, we show that PARP-1 is essential for the synergistic apoptotic effect and c-Jun N-terminal kinase 1 (JNK1) activation triggered by the ATRA/TNFα combination. JNK1 siRNAs reduce ATRA/TNFα-induced apoptosis, mitochondrial release of cytochrome c and caspase-9 activation. Altogether, these results identify a novel mechanism of PARP-1-induced apoptosis, in which JNK1 provides a link between PARP-1 activation and mitochondrial pathway of caspase-9 activation. This study also suggests that inclusion of nanomolar doses of ATRA could be clinically beneficial in amplifying TNFα-induced antitumor signals.Oncogene (2008) 27, 3361–3370; doi:10.1038/sj.onc.1210997; published online 17 December 2007 [ABSTRACT FROM AUTHOR]

Tumors that acquire resistance against death stimuli constitute a severe problem in the context of cancer therapy. To determine genetic alterations that favor the development of stress-resistant tumors in vivo, we took advantage of polyclonal tumors generated after retroviral infection of newborn Eλ-MYC mice, in which the retroviral integration acts as a mutagen to enhance tumor progression. Tumor cells were cultivated ex vivo and exposed to γ-irradiation prior to their transplantation into syngenic recipients, thereby providing a strong selective pressure for pro-survival mutations. Secondary tumors developing from stress-resistant tumor stem cells were analysed for retroviral integration sites to reveal candidate genes whose dysregulation confer survival. In addition to the gene encoding the antiapoptotic Bcl-xL protein, we identified the gadd45b locus to be a novel common integration site in these tumors, leading to enhanced expression. In accord with a thus far undocumented role of Gadd45β in tumorigenesis, we showed that NIH3T3 cells overexpressing Gadd45β form tumors in NOD/SCID mice. Interestingly and differently to other known ‘classical’ antiapoptotic factors, high Gadd45β levels did not protect against MYC-, UV- or γ-irradiation-induced apoptosis, but conferred a strong and specific survival advantage to serum withdrawal.Oncogene (2008) 27, 1429–1438; doi:10.1038/sj.onc.1210772; published online 24 September 2007 [ABSTRACT FROM AUTHOR]

Ovarian cancer is one of the leading causes of cancer death in women. A number of studies have suggested that synthetic retinoids may play an important role as an ovarian cancer chemotherapeutic agent. The synthetic retinoid CD 437 induces apoptosis in ovarian tumor cells by a mechanism that is not completely understood. In this study we demonstrate that CD437 treatment leads to an increase in GADD45A and GADD45B mRNA expression in CA-OV3 cells but not in CA-CD437R cells, a cell line which is resistant to CD437. This induction is specific to CD437 since no change in expression of either GADD45A or GADD45B was observed with either all-trans-RA or 4-HPR treatment. Western blot analysis demonstrated that the induction of GADD45A mRNA in the CA-OV3 cell line by CD437 was accompanied by an increase in GADD45A protein. Upregulation of GADD45A by CD437 is regulated at least in part at the post-transcriptional level. In contrast, CD437 regulates GADD45B expression by different mechanisms. The importance of GADD45A induction in mediating apoptosis was demonstrated in CA-OV3 cells overexpressing GADD45A antisense RNA (GADD45A-AS cells). Our results suggest that induction of GADD45A expression might play a role in mediating the apoptotic response of ovarian cancer cells to the synthetic retinoid CD437. J. Cell. Physiol. 212:771–779, 2007. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Somatostatin is a multifunctional hormone that modulates cell proliferation, differentiation and apoptosis. Mechanisms for somatostatin-induced apoptosis are at present mostly unsolved. Therefore, we investigated whether somatostatin receptor subtype 2 (sst2) induces apoptosis in the nontransformed murine fibroblastic NIH3T3 cells. Somatostatin receptor subtype 2 expression induced an executioner caspase-mediated apoptosis through a tyrosine phosphatase SHP-1 (Src homology domain phosphatase-1)-dependent stimulation of nuclear factor kappa B (NF-κB) activity and subsequent inhibition of the mitogen-activated protein kinase JNK. Tumor necrosis factor α (TNFα) stimulated both NF-κB and c-Jun NH2-terminal kinase (JNK) activities, which had opposite action on cell survival. Importantly, sst2 sensitized NIH3T3 cells to TNFα-induced apoptosis by (1) upregulating TNFα receptor protein expression, and sensitizing to TNFα-induced caspase-8 activation; (2) enhancing TNFα-mediated activation of NF-κB, resulting in JNK inhibition and subsequent executioner caspase activation and cell death. We have here unraveled a novel signaling mechanism for a G protein-coupled receptor, which directly triggers apoptosis and crosstalks with a death receptor to enhance death ligand-induced apoptosis.Cell Death and Differentiation (2007) 14, 197–208. doi:10.1038/sj.cdd.4401939; published online 28 April 2006 [ABSTRACT FROM AUTHOR]

The nuclear factor-kappaB (NF-κB) transcription factors have emerged as major regulators of programmed cell death (PCD) whether via apoptosis or necrosis. In this context, NF-κB's activity has important ramifications for normal tissue development, homoeostasis and the physiological functions of various cell systems including the immune, hepatic, epidermal and nervous systems. However, improper regulation of PCD by NF-κB can have severe pathologic consequences, ranging from neurodegeneration to cancer, where its activity often precludes effective therapy. Although NF-κB generally protects cells by inducing the expression genes encoding antiapoptotic and antioxidizing proteins, its role in apoptosis and necrosis can vary markedly in different cell contexts, and NF-κB can sensitize cells to death-inducing stimuli in some instances. This article describes our current knowledge of the role of NF-κB in apoptosis and necrosis, and focuses on the many advances since we last reviewed this rapidly evolving topic in Oncogene 3 years ago. There has been substantial progress in understanding NF-κB's mode of action in apoptosis and necrosis and the mechanisms that regulate its anti- vs proapoptotic activities. These recent developments shed new light on the role of NF-κB in many disease conditions including tumor development, tumor progression and anticancer treatment.Oncogene (2006) 25, 6800–6816. doi:10.1038/sj.onc.1209938 [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) are emerging as key effectors in signal transduction. This role of ROS is especially evident in the pathways leading to programmed cell death (PCD) elicited in response to certain stress stimuli and cytokines. In these pathways, cytotoxic ROS signaling appears to be mediated in part by activation of the c-Jun-N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) cascade. Another pathway that is under ROS-mediated control in some systems is that leading to activation of transcription factor nuclear factor-kappa B (NF-κB), which is a central regulator of immunity, inflammation and cell survival. Remarkably, new evidence has unveiled the existence of a reciprocal, negative control that NF-κB exerts on ROS and JNK activities. This NF-κB-imposed restraint on ROS and JNK signaling is crucial for antagonism of PCD elicited by the proinflammatory cytokine tumor necrosis factor (TNF)α and likely other triggers. Effectors of this antagonistic cross-talk between NF-κB and ROS/JNK pathways have recently been identified. Because of the key roles that the prosurvival function of NF-κB plays in organismal physiology and disease, gaining a further mechanistic understanding of this cross-talk and NF-κB-dependent survival may be key to developing new therapies for the treatment of widespread human illnesses, such as cancer and chronic inflammatory conditions.Oncogene (2006) 25, 6731–6748. doi:10.1038/sj.onc.1209936 [ABSTRACT FROM AUTHOR]

The gadd45 family of gene(s) is rapidly induced by genotoxic stress or by differentiation-inducing cytokines. Using bone marrow (BM) from gadd45a−/−, gadd45b−/− and wild-type (wt) mice, we investigated their role in stress responses of myeloid cells to acute stimulation with differentiating cytokines, myelotoxic agents and inflammatory substances. Bone marrow cells from gadd45a−/− and gadd45b−/− mice displayed compromised myeloid differentiation and higher apoptosis in vitro, following acute stimulation with a variety of differentiating cytokines. Intriguingly, gadd45a−/− and gadd45b−/− colony forming units granulocyte/macrophage progenitors displayed prolonged proliferation capacity compared to wt controls upon re-plating in methylcellulose supplemented with interleukin-3. The recovery of the BM myeloid compartment following 5-Fluorouracil-induced myelo-ablation was much slower in gadd45a−/− and gadd45b−/− mice compared to wt controls. Furthermore, the response of myeloid cells to inflammatory stress, inflicted via intraperitoneal administration of sodium caseinate was impaired in gadd45a−/− and gadd45b−/− mice compared to age-matched wt mice, as indicated by lower percentage of Gr-1-positive cells in the BM and lower number of myeloid cells in peritoneal exudates. Overall, these data indicate that both gadd45a and gadd45b play a role in modulating physiological stress responses of myeloid cells to acute stimulation with differentiating cytokines, myelo-ablation and inflammation. These findings should aid in understanding the response of normal and malignant hematopoietic cells to physiological and chemical stressors including anticancer agents.Oncogene (2006) 25, 5537–5546. doi:10.1038/sj.onc.1209555; published online 29 May 2006 [ABSTRACT FROM AUTHOR]

The activation of NF-κB inhibits apoptosis via a mechanism involving upregulation of various antiapoptotic genes, such as cellular FLICE-inhibitory protein (c-FLIP), Bcl-xL, A1/Bfl-1, and X chromosome-liked inhibitor of apoptosis (XIAP). In contrast, the activation of c-Jun N-terminal kinase (JNK) promotes apoptosis in a manner that is dependent on the cell type and the context of the stimulus. Recent studies have indicated that one of the antiapoptotic functions of NF-κB is to downregulate JNK activation. Further studies have also revealed that NF-κB inhibits JNK activation by suppressing accumulation of reactive oxygen species (ROS). In this review, we will focus on the signaling crosstalk between the NF-κB and JNK cascades via ROS.Cell Death and Differentiation (2006) 13, 730–737. doi:10.1038/sj.cdd.4401830; published online 9 December 2005 [ABSTRACT FROM AUTHOR]

NF-κB/Rel transcription factors have recently emerged as crucial regulators of cell survival. Activation of NF-κB antagonizes programmed cell death (PCD) induced by tumor necrosis factor-receptors (TNF-Rs) and several other triggers. This prosurvival activity of NF-κB participates in a wide range of biological processes, including immunity, lymphopoiesis and development. It is also crucial for pathogenesis of various cancers, chronic inflammation and certain hereditary disorders. This participation of NF-κB in survival signaling often involves an antagonism of PCD triggered by TNF-R-family receptors, and is mediated through a suppression of the formation of reactive oxygen species (ROS) and a control of sustained activation of the Jun-N-terminal kinase (JNK) cascade. Effectors of this antagonistic activity of NF-κB on this ROS/JNK pathway have been recently identified. Indeed, further delineating the mechanisms by which NF-κB promotes cell survival might hold the key to developing new highly effective therapies for treatment of widespread human diseases.Cell Death and Differentiation (2006) 13, 712–729. doi:10.1038/sj.cdd.4401865; published online 3 February 2006 [ABSTRACT FROM AUTHOR]

TNF-α activates several intracellular pathways to regulate inflammation, cell death, and proliferation. In the liver, TNF-a is not only a mediator of hepatotoxicity but also contributes to the restoration of functional liver mass by driving hepatocyte proliferation and liver regeneration. This review summarizes recent advances in TNF-α signaling mechanisms that demonstrate how the IKK, ROS, and JNK pathways interact with each other to regulate hepatocyte apoptosis and proliferation. Activation of these pathways is causatively linked to liver injury induced by concanavalin A, TNF-α, and ischemia-reperfusion and to liver regeneration and hepatocarcinogenesis. In light of recent findings, pharmacological inhibitors of JNK and IKK and antioxidants may be promising new tools for the treatment of hepatitis, ischemia-reperfusion injury, and hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]

All-trans retinoic acid (ATRA) significantly improves the survival of patients with acute promyelocytic leukemia (APL) by inducing granulocytic differentiation of leukemia cells. Since an activation of the transcription factor NF-κB occurs during ATRA-induced maturation of APL cells, a mechanistic link between these two processes was investigated. Using an in vitro model for APL, we report that ectopic overexpression of a repressor of NF-κB activation did not affect granulocytic differentiation. Importantly, NF-κB inhibition markedly resulted in a decreased viability of the differentiated cells, which correlated with increased apoptosis. Apoptosis was accompanied by a sustained activation of the c-Jun N-terminal kinase (JNK). Inhibition of JNK by the specific inhibitor SP600125 or by transfection of a dominant-negative mutant of JNK1 reduced the percentage of apoptotic cells, thus showing that JNK activation constitutes a death signal. Furthermore, impairment of NF-κB activation resulted in increased levels of reactive oxygen species (ROS) upon ATRA treatment. ROS accumulation was suppressed by the antioxidant butylated hydroxyanisol, which also abolished ATRA-induced JNK activation and apoptosis. Altogether, our results demonstrate an antiapoptotic effect of NF-κB activation during ATRA-induced differentiation of NB4 cells and identify repression of ROS-mediated JNK activation as a mechanism for this effect. Our observations also suggest that NF-κB signalling may contribute to an accumulation of mature APL cells and participate in the development of ATRA syndrome.Oncogene (2005) 24, 7145–7155. doi:10.1038/sj.onc.1208889; published online 25 July 2005 [ABSTRACT FROM AUTHOR]

Two cell lines that exemplify erythropoietin (EPO) receptor-positive tumors, human renal carcinoma cell lines RCC and the myelomonocytic leukemia cell line U937, were investigated for the apoptosis-modulatory potential of EPO. Cells cultured in the presence of EPO exhibited an elevated apoptotic response to cancer chemotherapeutic agents such as daunorubicin (Dauno) and vinblastine (VBL). Chemosensitization by EPO did not involve an increase in p53 activation, yet correlated with enhanced Bax/Bak-dependent mitochondrial membrane perturbation and caspase maturation. In vitro monotherapy with Dauno or VBL induced the degradation of I?Ba, provoked the translocation of NF-?B p65/50 to the nucleus and stimulated the expression of an NF-?B-activatable reporter gene. All these signs of NF-?B activation were perturbed in the presence of EPO. Inhibition of JAK2, one of the receptor-proximal elements of EPO-mediated signal transduction, greatly diminished the EPO-mediated chemosensitization and NF-?B inhibition. EPO lost its death-facilitating effects in the presence of an NF-?B inhibitor, underscoring the cause-effect relationship between EPO-mediated chemosensitization and NF-?B inhibition. Altogether, these results suggest that, at least in a specific subset of tumors, EPO receptor agonists can prevent activation of the NF-?B pathway, thereby enhancing the propensity of EPO receptor-positive tumor cells to undergo apoptosis.Oncogene (2005) 24, 737-745. doi:10.1038/sj.onc.1208205 Published online 6 December 2004 [ABSTRACT FROM AUTHOR]

The cytotoxicity of dental monomers has been widely investigated, but the underlying mechanisms have not been elucidated. We studied the molecular mechanisms involved in cell death induced by HEMA. In human primary fibroblasts, HEMA induced a dose-dependent apoptosis that was confirmed by the activation of caspases-8, -9, and -3. We found an increase of reactive oxygen species (ROS) and NF-κB activation after HEMA exposure. Blocking of ROS production by anti-oxidants had no direct influence on apoptosis caused by HEMA, but inhibition of NF-κB increased the fraction of apoptotic cells. Accordingly, mouse embryonic fibroblasts (MEF) from p65-/- mice were more susceptible to HEMA-induced apoptosis than were wild-type controls. Our results indicate that exposure to HEMA triggers apoptosis and that this mechanism is not directly dependent upon redox signaling. Nevertheless, ROS induction by HEMA activates NF-κB, which exerts a protective role in counteracting apoptosis. [ABSTRACT FROM AUTHOR]

The antitumor activity of the sesquiterpene lactone parthenolide, an active ingredient of medicinal plants, is believed to be due to the inhibition of DNA binding of transcription factors NF-?B and STAT-3, reduction in MAP kinase activity and the generation of reactive oxygen. In this report, we show that parthenolide activates c-Jun N-terminal kinase (JNK), which is independent of inhibition of NF-?B DNA binding and generation of reactive oxygen species. Parthenolide reversed resistance of breast cancer cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. Cancer cells treated with a combination of TRAIL and parthenolide underwent massive typical apoptosis and atypical apoptosis involving the loss of plasma membrane integrity. JNK activity is necessary for the parthenolide-induced sensitization to TRAIL because a dominant-negative JNK or the JNK inhibitor SP600125 reduced TRAIL plus parthenolide-induced apoptosis. Parthenolide induced phosphorylation of Bid and increased TRAIL-dependent cleavage of Bid without affecting caspase 8 activities. Cytochrome c but not Smac/DIABLO was released from the mitochondria in cells treated with parthenolide alone. Parthenolide through JNK increased the TRAIL-mediated degradation of the antiapoptotic protein X-linked inhibitor of apoptosis (XIAP). Enhanced XIAP cleavage correlated with increased and prolonged caspase 3 activity and PARP cleavage, suggesting that the sensitization to TRAIL involves‘feed forward’activation of caspase 3. These results identify a new antitumor activity of parthenolide, which can be exploited to reverse resistance of cancer cells to TRAIL, particularly those with elevated XIAP levels.Oncogene (2004) 23, 7330-7344. doi:10.1038/sj.onc.1207995 Published online 2 August 2004 [ABSTRACT FROM AUTHOR]

Recent studies strongly suggest an active involvement of the c-Jun N-terminal kinase (JNK) signaling pathway in tumor necrosis factor (TNF)-induced apoptosis. The direct evidence for the role of JNK and its isoforms has been missing and the mechanism of how JNK actually could facilitate this process has remained unclear. In this study, we show that Jnk2-/- primary mouse embryonic fibroblasts (pMEFs) exhibit resistance towards TNF-induced apoptosis as compared to corresponding wild-type and Jnk1-/- pMEFs. JNK2-deficient pMEFs could be resensitized to TNF via retroviral transduction of any of the four different JNK2 splicing variants. Jnk2-/- pMEFs displayed deficient and delayed effector caspase activation as well as impaired cytosolic cystein cathepsin activity: processes that both were needed for efficient TNF-induced apoptosis in pMEFs. Our work demonstrates that JNK has a central role in the promotion of TNF-induced apoptosis in pMEFs, and that the JNK2 isoform can regulate both mitochondrial and lysosomal death pathways in these cells.Cell Death and Differentiation (2004) 11, 301-313. doi:10.1038/sj.cdd.4401353 Published online 12 December 2003 [ABSTRACT FROM AUTHOR]

During their lifetime, cells encounter many life or death situations that challenge their very own existence. Their survival depends on the interplay within a complex yet precisely orchestrated network of proteins. The Rel/NF-?B signaling pathway and the transcription factors that it activates have emerged as critical regulators of the apoptotic response. These proteins are best known for the key roles that they play in normal immune and inflammatory responses, but they are also implicated in the control of cell proliferation, differentiation, apoptosis and oncogenesis. In recent years, there has been remarkable progress in understanding the pathways that activate the Rel/NF-?B factors and their role in the cell's decision to either fight or surrender to apoptotic challenge. Whereas NF-?B is most commonly involved in suppressing apoptosis by transactivating the expression of antiapoptotic genes, it can promote programmed cell death in response to certain death-inducing signals and in certain cell types. This review surveys our current understanding of the role of NF-?B in the apoptotic response and focuses on many developments since this topic was last reviewed in Oncogene 4 years ago. These recent findings shed new light on the activity of NF-?B as a critical regulator of apoptosis in the immune, hepatic, epidermal and nervous systems, on the mechanisms through which it operates and on its role in tissue development, homoeostasis and cancer.Oncogene (2003) 22, 8961-8982. doi:10.1038/sj.onc.1207230 [ABSTRACT FROM AUTHOR]

Tumor necrosis factor-α (TNF-α) is a multifunctional cytokine involved in the expression of many genes integral to the inflammatory response. In addition, it activates both apoptotic and survival pathways, the latter being mediated through the activation of the transcription factor nuclear factor-κB (NF-κB). Protein kinase CK2, a serine-threonine kinase that is universally upregulated in human malignancies, may be involved at multiple levels in this process. However, its role in mediating a survival response within colon cancer cells remains incompletely understood. Here we report that inhibition of CK2 in HCT-116 and HT-29 cells with the use of two specific CK2 inhibitors, 5,6-dichlororibifuranosylbenzimidazole (DRB) and apigenin, effected a synergistic reduction in cell survival when used in conjunction with TNF-α. Furthermore, there was a demonstrable synergistic reduction in colony formation in soft agar with the use of the same combinations. Western blot analysis showed that poly-ADP ribose polymerase and procaspase-3 cleavage complemented the fluorescence-activated cell sorter analysis findings of significantly increased subdiploid DNA-containing cell populations using these conditions. Remarkably, these events occurred in the absence of any reduction in the expression of the Bcl-2 family members Bcl-2, Mcl-1, and Bcl-x[sub L] or any change in the proapoptotic molecules Bad or Bax. One-hybrid NF-κB promoter assays utilizing a Gal4-p65 transactivation domain construct revealed that the TNF-induced transactivation was inhibited by both DRB and apigenin. This was associated with a concomitant reduction in the expression of a recognized anti-apoptotic NF-κB target, manganese superoxide dismutase, demonstrated by Q-PCR. Our findings indicate a potentially novel strategy for the treatment of colon cancer, one that targets CK2 simultaneous with TNF-α administration. [ABSTRACT FROM AUTHOR]

Interactions between proteasome and cyclin-dependent kinase inhibitors have been examined in human leukemia cells in relation to induction of apoptosis. Simultaneous exposure (24?h) of U937 myelomonocytic leukemia cells to 100?nM flavopiridol and 300?nM MG-132 resulted in a marked increase in mitochondrial injury (cytochrome c, Smac/DIABLO release, loss of ??m), caspase activation, and synergistic induction of cell death, accompanied by a marked decrease in clonogenic potential. Similar effects were observed with other proteasome inhibitors (e.g., Bortezomib (VELCADE™ bortezomib or injection), lactacystin, LLnL) and cyclin-dependent kinase inhibitors (e.g., roscovitine), as well as other leukemia cell types (e.g., HL-60, Jurkat, Raji). In U937 cells, synergistic interactions between MG-132 and flavopiridol were associated with multiple perturbations in expression/activation of signaling- and survival-related proteins, including downregulation of XIAP and Mcl-1, activation of JNK and p34cdc2, and diminished expression of p21CIP1. The lethal effects of MG-132/flavopiridol were not reduced in leukemic cells ectopically expressing Bcl-2, but were partially attenuated in cells ectopically expressing dominant-negative caspase-8 or CrmA. Flavopiridol/proteasome inhibitor-mediated lethality was also significantly diminished by agents and siRNA blocking JNK activation. Lastly, coadministration of MG-132 with flavopiridol resulted in diminished DNA binding of NF-?B. Notably, pharmacologic interruption of the NF-?B pathway (e.g., by BAY 11-7082, PDTC, or SN-50) or molecular dysregulation of NF-?B (i.e., in cells ectopically expressing an I?Ba super-repressor) mimicked the actions of proteasome inhibitors in promoting flavopiridol-induced mitochondrial injury, JNK activation, and apoptosis. Together, these findings indicate that proteasome inhibitors strikingly lower the apoptotic threshold of leukemic cells exposed to pharmacologic CDK inhibitors, and suggest that interruption of the NF-?B cytoprotective pathway and JNK activation both play key roles in this phenomenon. They also raise the possibility that combining proteasome and CDK inhibitors could represent a novel antileukemic strategy.Oncogene (2003) 22, 7108-7122. doi:10.1038/sj.onc.1206863 [ABSTRACT FROM AUTHOR]

In addition to its primary role as growth factor, human growth hormone (hGH) can also participate in cell survival, as already documented by its protective effect on human monocytes or human promyelocytic leukaemia U937 cells exposed to a Fas-mediated cell death signal. However, despite similarities in the molecular events following Fas and TNF-alpha receptor engagement, we report that U937 cells, genetically engineered to constitutively produce hGH, were made more sensitive to TNF-alpha-induced apoptosis than parental cells. This was due to overproduction of the antioxidant glutathione, which decreased the nuclear factor (NF)-kappaB activity known to control the expression of survival genes. These findings were confirmed in vivo, in nude mice bearing U937 tumours coinjected with recombinant hGH and the NF-kappaB -inducing anticancer drug daunorubicin, to avoid the in vivo toxicity of TNF-alpha. This study therefore highlights one of the various properties of hGH that may have potential clinical implications. [ABSTRACT FROM AUTHOR]

Inducible protection from apoptosis in vivo controls the size of cell populations. An important question in this respect is how differentiation affects mechanisms of apoptosis regulation. Among mature T lymphocytes, the NF-?B/Rel transcription factors are coupled to receptors that control cell population sizes by concurrently regulating survival and multiplication. In the present study, we used a transgenic inhibitor of NF-?B/Rel signaling to investigate the role of this pathway in proliferation and death of mature T cells in vivo. The results indicate that NF-?B integrates two critical yet distinct molecular pathways preventing apoptosis affected by the death receptor Fas, coordinately regulating levels of FLIP and Bcl-xL in primary T cells. Surprisingly, NF-?B blockade preferentially impacted naive as compared to memory T cells. The Fas/FasL pathway was linked to these findings by evidence that the abnormalities imposed by NF-?B inhibition were ameliorated by Fas deficiency, particularly for the CD4+ lineage. Moreover, levels of an inhibitor of Fas-mediated apoptosis, c-FLIP, were diminished in cells expressing the transgenic inhibitor. NF-?B was also linked to T cell survival in vivo by mediating induction of Bcl-xL: restoration of Bcl-xL levels reversed the preferential deficit of naive T cells, differentially impacting the CD4 and CD8 subsets. These results show that promoting survival and effective multiplication are central roles for NF-?B in T lymphoid homeostasis in vivo, but this effect and its underlying mechanisms are influenced by the developmental state of the lymphocyte.Cell Death and Differentiation (2003) 10, 1032-1044. doi:10.1038/sj.cdd.4401257 [ABSTRACT FROM AUTHOR]

NF-κB has been implicated in the regulation of apoptosis, a key mechanism of normal and malignant growth control. Previously, we demonstrated that inhibition of NF-κB activity by TGF-β1 leads directly to induction of apoptosis of murine B-cell lymphomas and hepatocytes. Thus, we were surprised to determine that NF-κB is transiently activated in response to TGF-β1 treatment. Here we elucidate the mechanism of TGF-β1-mediated regulation of NF-κB and induction of apoptosis in epithelial cells. We report that TGF-β1 activates IKK kinase, which mediates IκB-α phosphorylation. In turn, the activation of IKK following TGF-β1 treatment is mediated by the TAK1 kinase. As a result of NF-κB activation, IκB-α mRNA and protein levels are increased leading to postrepression of NF-κB and induction of cell death. Inhibition of NF-κB following TGF-β1 treatment increased AP-1 complex transcriptional activity through sustained c-Jun phosphorylation, thereby potentiating AP-1/SMADs-mediated cell killing. Furthermore, TGF-β1-mediated upregulation of Smad7 appeared independent of NF-κB. In hepatocellular carcinomas of TGF-β1 or TGF-α/c-myc transgenic mice, we observed constitutive activation of NF-κB that led to inhibition of JNK signaling. Overall, our data illustrate an autocrine mechanism based on the ability of IKK/NF-κB/IκB-α signaling to negatively regulate NF-κB levels thereby permitting TGF-β1-induced apoptosis through AP-1 activity.Oncogene (2003) 22, 412–425. doi:10.1038/sj.onc.1206132 [ABSTRACT FROM AUTHOR]