Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.25.1 (proteasome)
28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bortezomib is the first proteasome inhibitor to be used clinically for the treatment of multiple myeloma and has been suggested as a possible treatment for a wide variety of hematologic and solid malignancies. Recent data suggests that potent immunomodulatory effects can also occur with systemic proteasome inhibition. This has been recently shown to occur in a graft-versus host disease model following bone marrow transplantation in mice. The suggested direct immunological effects of bortezomib treatment to include a decrease in anti-apoptotic protein levels, an increase in expression of TNF-family receptors (specifically Apo2L/TRAIL), induction of apoptosis, and inhibition of the transcription factor NF-kappaB. The NF-kappaB pathway has been associated with the regulation of numerous immune and inflammatory response mediators. In this review, we will present recent information concerning the potential therapeutic implications of bortezomib for a range of immune disorders. These findings would suggest that bortezomib treatment may be of clinical significance to suppress solid organ transplant rejection, autoreactive T cell responses, pro-inflammatory cytokine production, and consequently disease progression and pathology in autoimmunity.
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PMID:Use of systemic proteasome inhibition as an immune-modulating agent in disease. 1734 2

LPS stimulates monocytes/macrophages through the activation of signaling events that modulate the production of inflammatory cytokines. Apigenin, a flavonoid abundantly found in fruits and vegetables, exhibits anti-proliferative and anti-inflammatory activities through poorly defined mechanisms. In this study, we demonstrate that apigenin inhibits the production of proinflammatory cytokines IL-1beta, IL-8, and TNF in LPS-stimulated human monocytes and mouse macrophages. The inhibitory effect on proinflammatory cytokine production persists even when apigenin is administered after LPS stimulation. Transient transfection experiments using NF-kappaB reporter constructs indicated that apigenin inhibits the transcriptional activity of NF-kappaB in LPS-stimulated mouse macrophages. The classical proteasome-dependent degradation of the NF-kappaB inhibitor IkappaBalpha was observed in apigenin LPS-stimulated human monocytes. Using EMSA, we found that apigenin does not alter NF-kappaB-DNA binding activity in human monocytes. Instead we show that apigenin, as part of a non-canonical pathway, regulates NF-kappaB activity through hypophosphorylation of Ser536 in the p65 subunit and the inactivation of the IKK complex stimulated by LPS. The decreased phosphorylation on Ser536 observed in LPS-stimulated mouse macrophages treated with apigenin was overcome by the over-expression of IKKbeta. In addition, our studies indicate that apigenin inhibits in vivo LPS-induced TNF and the mortality induced by lethal doses of LPS. Collectively, these findings suggest a molecular mechanism by which apigenin suppresses inflammation and modulates the immune response in vivo.
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PMID:Apigenin blocks lipopolysaccharide-induced lethality in vivo and proinflammatory cytokines expression by inactivating NF-kappaB through the suppression of p65 phosphorylation. 1798 4

Lupus treatment has evolved considerably with spectacular advances that can be summarized in 10 points. Hydroxychloroquine and cyclophosphamide are still standard drugs, provided their use is optimized. Contraception and postmenopausal hormone replacement therapy have finally been tested in randomized studies with fairly reassuring results, although prudence remains essential in patients with severe lupus and above all in those with thrombotic complications (antiphospholipid syndrome). Mycophenolic acid has been shown to be useful in the treatment of lupus nephropathies, but its specific place in the therapeutic strategy remains to be defined. Other drugs (sirolimus, abatacept) are currently being evaluated. Anti-lymphocyte B therapies are growing in popularity. Rituximab and other drugs (anti-BAFF, TACI-Fc) are also being evaluated and their results appear very interesting. Interferon alpha (type I) inhibition is an attractive therapeutic approach in lupus but its use in humans is still premature. Peptide vaccination with fragments of autoantibodies or autoantigens is an elegant strategy, and preliminary results justify further studies. Anti-TNF molecules may be beneficial in lupus. Complement inhibition can be useful in lupus and antiphospholipid syndrome but drugs usable in humans (anti-C5) must be developed. Atheromatosis in lupus is the principal cause of morbidity and mortality and must be managed. Smoking cessation is essential, but other approaches (statins) should also be discussed. Many futuristic types of immune manipulation may be envisioned (proteasome inhibition, modulation of Fc gammaRIIB, and modulation of cell signaling (PI3kgamma)). Hence the perspectives are numerous. We will soon be able to optimize the treatment of our patients. Nevertheless, rigorous evaluation of the risk/benefit ratio of new drugs and of their most appropriate place in the therapeutic strategy against systemic lupus is indispensable.
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PMID:[Systemic lupus erythematosus: news and therapeutic perspectives]. 1824 45

Apoptosis in response to TRAIL or TNF requires the activation of initiator caspases, which then activate the effector caspases that dismantle cells and cause death. However, little is known about the dynamics and regulatory logic linking initiators and effectors. Using a combination of live-cell reporters, flow cytometry, and immunoblotting, we find that initiator caspases are active during the long and variable delay that precedes mitochondrial outer membrane permeabilization (MOMP) and effector caspase activation. When combined with a mathematical model of core apoptosis pathways, experimental perturbation of regulatory links between initiator and effector caspases reveals that XIAP and proteasome-dependent degradation of effector caspases are important in restraining activity during the pre-MOMP delay. We identify conditions in which restraint is impaired, creating a physiologically indeterminate state of partial cell death with the potential to generate genomic instability. Together, these findings provide a quantitative picture of caspase regulatory networks and their failure modes.
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PMID:Quantitative analysis of pathways controlling extrinsic apoptosis in single cells. 1840 23

Innate immune signaling is critical for the development of protective immunity. Such signaling is, perforce, tightly controlled. Lipoxins (LXs) are eicosanoid mediators that play key counterregulatory roles during infection. The molecular mechanisms underlying LX-mediated control of innate immune signaling are of interest. In this study, we show that LX and aspirin (ASA)-triggered LX (ATL) inhibit innate immune signaling by inducing suppressor of cytokine signaling (SOCS) 2-dependent ubiquitinylation and proteasome-mediated degradation of TNF receptor-associated factor (TRAF) 2 and TRAF6, which are adaptor molecules that couple TNF and interleukin-1 receptor/Toll-like receptor family members to intracellular signaling events. LX-mediated degradation of TRAF6 inhibits proinflammatory cytokine production by dendritic cells. This restraint of innate immune signaling can be ablated by inhibition of proteasome function. In vivo, this leads to dysregulated immune responses, accompanied by increased mortality during infection. Proteasomal degradation of TRAF6 is a central mechanism underlying LX-driven immune counterregulation, and a hitherto unappreciated mechanism of action of ASA. These findings suggest a new molecular target for drug development for diseases marked by dysregulated inflammatory responses.
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PMID:Native and aspirin-triggered lipoxins control innate immunity by inducing proteasomal degradation of TRAF6. 1980 49

Estrogen-induced proliferation in estrogen receptor (ER)-positive breast cancer cells is primarily mediated through two distinct intracellular receptors, ER alpha and ER beta. Although tumor necrosis factor alpha (TNF alpha) and E2/ER alpha are known to exert opposing effects on cell proliferation in MCF-7 cells, the mechanism by which TNFalpha antagonizes E2/ER alpha-mediated cell proliferation is not well understood. The present study suggests that reduced cell survival in response to TNF alpha treatment in MCF-7 cells may be associated with the down-regulation of ER alpha protein. The decrease in ER alpha protein level was accompanied by an inhibition of ER alpha gene transcription. Cell viability was decreased synergistically by the combined treatment with ER alpha-siRNA and TNF alpha. Furthermore, pretreatment of cells with the PI3-kinase (PI3K)/Akt inhibitor, LY294002, markedly enhanced TNF alpha-induced down-regulation of the ER alpha protein, suggesting that the PI3K/Akt pathway might be involved in control of the ER alpha level. Moreover, down-regulation of ER alpha by TNF alpha was not inhibited in cells that were pretreated with the proteasome inhibitors, MG132 and MG152, which suggests that proteasome-dependent proteolysis does not significantly influence TNF alpha-induced down-regulation of ER alpha protein. In contrast, the effect of the PI3K/Akt inhibitor on ER alpha was blocked in cells that were treated with LY294002 in the presence of the proteasome inhibitors. Collectively, our findings show that the TNF alpha may partly regulate the growth of MCF-7 breast cancer cells through the down-regulation of ER alpha expression, which is primarily mediated by a PI3K/Akt signaling.
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PMID:TNF alpha-induced down-regulation of estrogen receptor alpha in MCF-7 breast cancer cells. 1848 65

Acute myeloid leukemia (AML) is a malignant disease characterized by abnormal proliferation of clonal precursor cells. Although different strategies have been adopted to obtain complete remission, the disease actually progresses in about 60-70% of patients. Bortezomib has been used in multiple myeloma and other lymphoid malignancies because of its antitumor activity. Here we examined the sensitivity of bone marrow cells from AML patients (34 patients: 25 newly diagnosed, 4 relapsed, 5 refractory) to bortezomib alone or in combination with TRAIL, a member of the TNF family that induces apoptosis in tumor cells while sparing normal cells. Bortezomib induced cell death in blasts from each patient sample. The cytotoxic effect was dose- and time-dependent (concentration from 0.001 to 10 microM for 24 and 48 h) and was associated with a downregulation of Bcl-xL and Mcl-1, an upregulation of TRAIL-R1, TRAIL-R2, p21, activation of executioner caspases and a loss of the mitochondrial membrane potential. Moreover, low doses of bortezomib primed TRAIL-resistant AML cells for enhanced TRAIL-mediated killing. These results suggest that a combination of proteasome inhibitors and TRAIL could be effective for treating AML patients, even patients who are refractory to conventional chemotherapy.
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PMID:Antitumor activity of bortezomib alone and in combination with TRAIL in human acute myeloid leukemia. 1871 97

The proinflammatory cytokine tumor necrosis factor alpha (TNFalpha) has been linked to inflammation- and cancer-related anemia, which reduces both quality of life and prognosis of patients. The aim of this study was to reveal molecular mechanisms linked to the inhibition of erythroid differentiation by TNFalpha. In this study, we showed that the inhibition of erythropoietin (Epo)-mediated differentiation by TNFalpha lead to a downregulation of hemoglobin synthesis and was correlated to a modulation of key erythroid transcription factors. Thus, a reverse of the transcription factor GATA-1/GATA-2 balance normally present during erythropoiesis, as well as a downregulation of the cofactor of GATA-1, friend of GATA-1 (FOG-1), and the coregulating transcription factor nuclear factor erythroid 2 (NF-E2) was observed after TNFalpha treatment. Moreover, we showed a reduction of GATA-1/FOG-1 interaction due to a reduced transcription of GATA-1 and a proteasome-dependent FOG-1 degradation after TNFalpha treatment. These changes led to an inhibition of erythroid gene expression including Epo receptor (EpoR), alpha- and gamma-globin, erythroid-associated factor (ERAF), hydroxymethylbilane synthetase (HMBS), and glycophorin A (GPA). An analysis of distinct signaling pathway activations then revealed an activation of p38 by TNF, as well as a corresponding involvement of this mitogen-activated protein kinase (MAPK) in the cytokine-dependent inhibition of erythroid differentiation. Indeed the p38 inhibitor, SB203580, abrogated the inhibitory effect of TNFalpha on the major erythroid transcription factor GATA-1 as well as erythroid marker expression in Epo-induced TF-1 cells. Overall, these data contribute to a better understanding of cytokine-dependent anemia, by giving first hints about key erythroid transcription factor modulations after TNFalpha treatment as well as an involvement of p38 in the inhibition of erythroid differentiation.
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PMID:Tumor necrosis factor alpha inhibits erythroid differentiation in human erythropoietin-dependent cells involving p38 MAPK pathway, GATA-1 and FOG-1 downregulation and GATA-2 upregulation. 1880 1

Tumor necrosis factor-alpha (TNFalpha) stimulation of hepatocytes induces either cell survival or apoptosis, which seems to be regulated by the ubiquitin-proteasome system. Here we investigated the role of TNFalpha-induced down-modulation of the de-ubiquitinating enzyme USP2 for hepatocyte survival. Inhibition of hepatocyte apoptosis by pre-treatment with TNFalpha (TNFalpha tolerance) was analyzed in the mouse model of galactosamine/TNFalpha-induced liver injury and in actinomycin D/TNFalpha-treated primary mouse hepatocytes. The role of USP2 for TNFalpha-induced hepatocyte survival was studied using small interference RNA or an expression clone. Injection of mice or preincubation of hepatocytes with TNFalpha caused a rapid down-regulation of hepatic USP2-41kD, the predominant USP2 isoform in the liver. In vitro an artificial knockdown of USP2 inhibited actinomycin D/TNFalpha-induced hepatocyte apoptosis, which was associated with elevated levels of the anti-apoptotic protein c-Flip(L/S) and a concomitant decrease of cellular levels of the ubiquitinligase Itch, a negative regulator of c-Flip. USP2-41kD overexpression abrogated TNFalpha tolerance in vitro, prevented accumulation of c-Flip(L/S) and resulted in elevated levels of Itch. Accordingly, c-Flip(L/S) protein levels were elevated in livers of TNFalpha-tolerant mice, which correlated to a switch from JNK and ERK to p38 signaling after galactosamine/TNF re-challenge. Our results indicate that TNFalpha-induced USP2 down-regulation is an effective cytoprotective mechanism in hepatocytes. Hence, USP2 could be a novel pharmacological target, and specific USP2 inhibitors might be potential candidates for the treatment of inflammation-related apoptotic liver damage.
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PMID:Down-regulation of the de-ubiquitinating enzyme ubiquitin-specific protease 2 contributes to tumor necrosis factor-alpha-induced hepatocyte survival. 1900 62

Inducing apoptosis via the extrinsic death receptor pathway is an attractive anti-cancer treatment strategy, however, numerous cancer cells exhibit significant resistance to death ligand stimuli. Here, we investigated the anti-neoplastic capability of proteasome inhibition, through the administration of Velcade, to synergize with a death receptor agonist in vivo. The death ligand-resistant LNCaP prostate xenograft model was utilized. Tumors were established and mice were treated with Velcade, TRAIL (TNF-Related Apoptosis Inducing Ligand) or the combined regimen. Only mice treated with a combination of Velcade and TRAIL was tumor growth inhibited with a corresponding loss of the hemorrhagic phenotype, decreased tumor cell proliferation and increased tumor cell apoptosis. Next, to determine if the extrinsic pathway is critical for mediating the anti-tumor efficacy that can be achieved in some cell types with Velcade treatment alone, the death receptor sensitive PC-3 xenograft model was used. PC-3 tumors exhibited a 54% decrease in tumor volume in response to Velcade, while c-FLIP overexpressing PC-3 xenografts were resistant to the treatment. These findings suggest that the extrinsic apoptotic pathway can mediate the anti-tumor effects of Velcade and support the therapeutic use of proteasome inhibition in combination with a death receptor stimulus in the treatment of prostate cancer.
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PMID:Velcade sensitizes prostate cancer cells to TRAIL induced apoptosis and suppresses tumor growth in vivo. 1912 21


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