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Proteasome Inhibitor (proteasome + inhibitor)

Distribution by Scientific Domains

Medical Sciences	46%
Life Sciences	32%
Chemistry	20%

Distribution within Medical Sciences

Hematology	21%
Immunology	17%
8 Other Subdomains	41%

Terms modified by Proteasome Inhibitor

proteasome inhibitor bortezomib

Selected Abstracts

Innentitelbild: Chemical Proteomics Discloses Petrosapongiolide,M, an Antiinflammatory Marine Sesterterpene, as a Proteasome Inhibitor (Angew. Chem.

ANGEWANDTE CHEMIE, Issue 23 2010
23/2010)
Petrosaspongiolid,M, ein mariner Naturstoff mit entzündungshemmender Wirkung, hat ein erstaunliches pharmakologisches Profil. In ihrer Zuschrift auf S.,4052,ff. identifizieren A. Casapullo und Mitarbeiter die makromolekularen Zielstrukturen dieses Wirkstoffkandidaten , besonders wichtig ist der Angriff am 20S-Proteasom. [source]

Chemical Proteomics Discloses Petrosapongiolide,M, an Antiinflammatory Marine Sesterterpene, as a Proteasome Inhibitor,

ANGEWANDTE CHEMIE, Issue 23 2010
Luigi Margarucci
PM als Köder: Das marine ,-Hydroxybutenolid-Sesterterpenoid Petrosaspongiolid,M (PM) wurde an einer Festphase immobilisiert, um selektiv seine makromolekularen Zielstrukturen in einem Makrophagen-Zelllysat anzulagern. Dabei erwies sich das Proteasom als wichtigster Bindungspartner. [source]

TMC-95A Analogues with Endocyclic Biphenyl Ether Group as Proteasome Inhibitors

CHEMISTRY & BIODIVERSITY, Issue 1 2004
Markus Kaiser
TMC-95A, a cyclic tripeptide metabolite of Apiospora montagnei, is a potent competitive inhibitor of proteasome. Based on the X-ray structure of its complex with yeast proteasome, the synthetically challenging structure of this natural product was simplified in a first generation of analogues by replacing the highly oxidized side-chain biaryl system with a phenyl-oxindole group. In the present study, the TMC-95 biaryl group was substituted with a biphenyl ether with retainment of significant proteasome inhibition. Because of the facile synthetic access of tripeptides containing in i, i+2 positions residues of the isodityrosine type, this new generation of TMC-95 analogues may represent promising lead structures for further optimization of affinity and selectivity of proteasome inhibitors. [source]

Proteasome inhibitor-induced apoptosis in human monocyte-derived dendritic cells

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2006
Alessio Nencioni Dr.
Abstract Proteasome inhibitors possess potent antitumor activity against a broad spectrum of human malignancies. However, the effects of these compounds on the immune system still have to be clearly determined. In the present study, we have investigated the effects of proteasome inhibitors on dendritic cells (DC), antigen-presenting cells playing a key role in the initiation of immune responses. Exposure to the proteasome inhibitors bortezomib, MG132 or epoxomicin was found to promote apoptosis of human monocyte-derived DC and to reduce the yield of viable DC when given to monocytes early during differentiation to DC. DC apoptosis via proteasome inhibition was accompanied by mitochondria disruption and subsequent activation of the caspase cascade. Up-regulation and intracellular redistribution of Bcl-2-associated X,protein (Bax), a pro-apoptotic Bcl-2 family protein, were observed in DC treated with these compounds and represent a suitable mechanism leading to activation of the intrinsic apoptotic pathway. Finally, active protein synthesis was found to represent an upstream prerequisite for DC apoptosis induced by proteasome inhibitors, since the translation inhibitor cycloheximide blocked all of the steps of the observed apoptotic response. In conclusion, induction of apoptosis in DC may represent a novel mechanism by which proteasome inhibitors affect the immune response at the antigen-presenting cell level. [source]

BSc2118 is a novel proteasome inhibitor with activity against multiple myeloma

EUROPEAN JOURNAL OF HAEMATOLOGY, Issue 2 2010
Jan Sterz
Abstract Objectives:, The ubiquitin,proteasome system emerged as a new therapeutic target in cancer treatment. The purpose of this study was to elucidate the effects of the novel proteasome inhibitor BSc2118 on t(4;14) positive and negative multiple myeloma (MM) cells and normal peripheral blood mononuclear cells (PBMNC). Methods:, Human MM cell lines OPM-2, RPMI-8226, and U266 and primary MM cells from bone marrow aspirates were exposed to BSc2118. Cytotoxicity levels were evaluated using the MTT-test. BSc2118-induced apoptosis was analyzed by annexin-V assay. Further methods used included proteasomal activity determination, cell cycle analysis, western blot, and transcription factor assays. Results:, In OPM-2, RPMI-8226, U266 cell lines and primary MM cells, BSc2118 caused dose-dependent growth inhibitory effects. After 48 h, dose-dependent apoptosis occurred both in cell lines and primary myeloma cells irrespective of t(4;14). A significant G2-M cell cycle arrest occurred after 24 h. Furthermore, we observed a marked inhibition of intracellular proteasome activity, an increase in intracellular p21 levels, and an inhibition of NF-,B activation. The toxicity against PBMNC remained low, suggesting a broad therapeutic range of this agent. Conclusion:, Taken together, BSc2118 shows significant antimyeloma activity and may be considered as a promising agent in cancer drug development. [source]

The proteasome inhibitor bortezomib inhibits FGF-2-induced reduction of TAZ levels in osteoblast-like cells

EUROPEAN JOURNAL OF HAEMATOLOGY, Issue 1 2010
Homare Eda
Abstract Objectives:,Bortezomib (PS-341; VelcadeÔ), a proteasome inhibitor, is used as a therapeutic agent for multiple myeloma. Bortezomib has been shown to strongly induce osteoblast differentiation and elevate the levels of osteoblast-related differentiation markers in the serum of patients with myeloma. Bortezomib also reportedly increases the activity of the transcription factor, Runx2. However, the mechanism of action by which bortezomib-elevated Runx2 activity mediates osteoblast differentiation remains unclear. On the other hand, fibroblast growth factor 2 (FGF-2) is found at high levels in patients with multiple myeloma. We previously reported that FGF-2 reduces the levels of the transcriptional coactivator with PDZ-binding motif (TAZ). We therefore investigated the effects of bortezomib on TAZ protein levels in the presence of FGF-2. Methods: Osteoblastic MC3T3-E1 cells were treated with different concentrations of bortezomib in the presence or absence of FGF-2 and various biologic responses were investigated by immunoblotting, RT-PCR, quantitative PCR, and alizarin red staining. Results: We found that bortezomib inhibited FGF-2-induced reduction of TAZ levels through a pathway other than that used for proteasome inhibition, while maintaining TAZ function, which in turn, enhanced the expression of Runx2-transcribed osteogenic differentiation markers. Bortezomib also suppressed the antimineralization effect of FGF-2. Conclusions: These findings suggest that bortezomib inhibited FGF-2-induced reduction of TAZ and consequently stimulated osteogenic differentiation independently of proteasome inhibition. These findings may contribute to elucidate the osteolytic mechanism in multiple myeloma, and to the development of new drugs for multiple myeloma and other osteolytic diseases. [source]

Long-term suppression of tyrosinase by terrein via tyrosinase degradation and its decreased expression

EXPERIMENTAL DERMATOLOGY, Issue 6 2009
Seo-Hyoung Park
Abstract:, Previously, we reported that a fungal metabolite, terrein, decreases melanin synthesis via downregulation of microphthalmia-associated transcription factor (MITF). In the present study, we further investigated the long-term hypopigmenting action of terrein in a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Treatment with terrein at a concentration of 50 ,m strongly decreased melanogenesis in a time-dependent manner. Interestingly, the decreased tyrosinase protein levels lasted for at least 7 days, even though the MITF protein levels were restored after 3 days of treatment. In accordance with the results of Western blot analyses, the tyrosinase mRNA levels were found to be continuously decreased for at least 7 days, even though recovery of the MITF mRNA levels began after 3 days of terrein treatment. Therefore, we evaluated tyrosinase downregulation to determine if it is caused by proteasomal degradation. We found that the reduction in tyrosinase levels that was induced by terrein was clearly recovered by MG-132, a proteasome inhibitor. Moreover, ubiquitination of tyrosinase increased following treatment with terrein in the presence of MG-132. Taken together, these results suggest that terrein decreases melanogenesis through ubiquitin-dependent proteasomal degradation as well as via decreased expression of its mRNA. [source]

Cadmium blocks hypoxia-inducible factor (HIF)-1-mediated response to hypoxia by stimulating the proteasome-dependent degradation of HIF-1,

FEBS JOURNAL, Issue 13 2000
Yang-Sook Chun
Cadmium is a substantial industrial and environmental pollutant which seriously impairs erythropoiesis. Cd has been demonstrated to aggravate anemia by suppressing erythropoietin gene expression in anemic patients. As hypoxic induction of erythropoietin mRNA depends on a transcription factor, hypoxia-inducible factor 1 (HIF-1), we hypothesized that Cd suppresses the hypoxic activation of HIF-1. In hypoxic Hep3B cells, all mRNAs of various genes, which are known to be upregulated by HIF-1 activation under hypoxia, were suppressed by Cd in a dose-dependent manner. Cd inhibited the hypoxia-induced activity of luciferase in 293 cells which was transfected with a reporter plasmid carrying a hypoxia response element. By electrophoretic mobility gel shift assay, Cd inhibited the DNA-binding activity of HIF-1 in hypoxic Hep3B cells. Cd reduced the amount of HIF-1, protein in hypoxia, whereas it didn't affect HIF-1 , mRNA levels. Moreover, Cd inhibited HIF-1, accumulation induced by cobalt and desferrioxamine. Antioxidants and a proteasome inhibitor prevented the HIF-1, degradation caused by Cd. The possibility that oxidative stress mediates this action of Cd was examined. Cd didn't affect protein oxidation and reduced glutathione levels in hypoxic cells. These results indicate that Cd triggers a redox/proteasome-dependent degradation of HIF-1, protein, reducing HIF-1 activity and in turn suppressing the hypoxic induction of hypoxia-inducible genes. [source]

Modulation of Activation-Induced Cytidine Deaminase by Curcumin in Helicobacter pylori -Infected Gastric Epithelial Cells

HELICOBACTER, Issue 6 2009
Syed Faisal Haider Zaidi
Abstract Background:, Anomalous expression of activation-induced cytidine deaminase (AID) in Helicobacter pylori -infected gastric epithelial cells has been postulated as one of the key mechanisms in the development of gastric cancer. AID is overexpressed in the cells through nuclear factor (NF)-,B activation by H. pylori and hence, inhibition of NF-,B pathway can downregulate the expression of AID. Curcumin, a spice-derived polyphenol, is known for its anti-inflammatory activity via NF-,B inhibition. Therefore, it was hypothesized that curcumin might suppress AID overexpression via NF-,B inhibitory activity in H. pylori -infected gastric epithelial cells. Materials and Methods:, MKN-28 or MKN-45 cells and H. pylori strain 193C isolated from gastric cancer patient were used for co-culture experiments. Cells were pretreated with or without nonbactericidal concentrations of curcumin. Apoptosis was determined by DNA fragmentation assay. Enzyme-linked immunosorbent assay was performed to evaluate the anti-adhesion activity of curcumin. Real-time polymerase chain reaction was employed to evaluate the expression of AID mRNA. Immunoblot assay was performed for the analysis of AID, NF-,B, inhibitors of NF-,B (I,B), and I,B kinase (IKK) complex regulation with or without curcumin. Results:, The adhesion of H. pylori to gastric epithelial cells was not inhibited by curcumin pretreatment at nonbactericidal concentrations (,10 ,mol/L). Pretreatment with nonbactericidal concentration of curcumin downregulated the expression of AID induced by H. pylori. Similarly, NF-,B activation inhibitor (SN-50) and proteasome inhibitor (MG-132) also downregulated the mRNA expression of AID. Moreover, curcumin (,10 ,mol/L) has suppressed H. pylori -induced NF-,B activation via inhibition of IKK activation and I,B degradation. Conclusion:, Nonbactericidal concentrations of curcumin downregulated H. pylori -induced AID expression in gastric epithelial cells, probably via the inhibition of NF-,B pathway. Hence, curcumin can be considered as a potential chemopreventive candidate against H. pylori -related gastric carcinogenesis. [source]

Tumor necrosis factor-, augments lipopolysaccharide-induced suppressor of cytokine signalling 3 (SOCS-3) protein expression by preventing the degradation

IMMUNOLOGY, Issue 1 2010
Jargalsaikhan Dagvadorj
Summary The regulatory role of tumour necrosis factor-, (TNF-,) on the expression of suppressor of cytokine signalling 3 (SOCS-3) in response to lipopolysaccharide (LPS) was examined using peritoneal macrophages from TNF-,-deficient mice. The LPS-induced SOCS-3 expression was markedly augmented in macrophages from wild-type mice whereas such augmentation was not seen in the cells from TNF-,-deficient mice. However, there was no significant difference in the level of SOCS-3 messenger RNA expression between macrophages from wild-type mice and those from TNF-,-deficient mice. The addition of exogenous TNF-, augmented the LPS-induced SOCS-3 expression in macrophages from TNF-,-deficient mice. The pulse chase analysis suggested augmented degradation of LPS-induced SOCS-3 protein in macrophages from TNF-,-deficient mice. Moreover, MG 132, a 26S proteasome inhibitor, sustained the LPS-induced SOCS-3 expression in those cells. The tyrosine phosphorylation of SOCS-3 was definitely induced in LPS-stimulated macrophages from TNF-,-deficient mice but not wild-type mice. A tyrosine phosphatase inhibitor enhanced the tyrosine phosphorylation of SOCS-3 in wild-type mice and accelerated the degradation. Therefore, it was suggested that TNF-, prevented the degradation of SOCS-3 protein via inhibition of the tyrosine phosphorylation in LPS-stimulated macrophages. [source]

Proteasome inhibition with bortezomib suppresses growth and induces apoptosis in osteosarcoma

INTERNATIONAL JOURNAL OF CANCER, Issue 1 2010
Yuriy Shapovalov
Abstract Osteosarcomas are primary bone tumors of osteoblastic origin that mostly affect adolescent patients. These tumors are highly aggressive and metastatic. Previous reports indicate that gain of function of a key osteoblastic differentiation factor, Runx2, leads to growth inhibition in osteosarcoma. We have previously established that Runx2 transcriptionally regulates expression of a major proapoptotic factor, Bax. Runx2 is regulated via proteasomal degradation, and proteasome inhibition has a stimulatory effect on Runx2. In this study, we hypothesized that proteasome inhibition will induce Runx2 and Runx2-dependent Bax expression sensitizing osteosarcoma cells to apoptosis. Our data showed that a proteasome inhibitor, bortezomib, increased Runx2 and Bax in osteosarcoma cells. In vitro, bortezomib suppressed growth and induced apoptosis in osteosarcoma cells but not in nonmalignant osteoblasts. Experiments involving intratibial tumor xenografts in nude mice demonstrated significant tumor regression in bortezomib-treated animals. Immunohistochemical studies revealed that bortezomib inhibited cell proliferation and induced apoptosis in osteosarcoma xenografts. These effects correlated with increased immunoreactivity for Runx2 and Bax. In summary, our results indicate that bortezomib suppresses growth and induces apoptosis in osteosarcoma in vitro and in vivo suggesting that proteasome inhibition may be effective as an adjuvant to current treatment regimens for these tumors. Published 2009 UICC. This article is a US Government work and, as such, is in the public domain in the United States of America. [source]

JNK phosphorylates the HSF1 transcriptional activation domain: Role of JNK in the regulation of the heat shock response

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2001
Jeonghyeon Park
Abstract The role of c-Jun NH2 -terminal kinase (JNK) signaling cascade in the stress-inducible phosphorylation of heat shock factor 1 (HSF1) was investigated using known agonists and antagonists of JNK. We showed that treatment of HeLa cells with MG132, a proteasome inhibitor and known JNK activator, caused the transcriptional activation domain of HSF1 to be targeted and phosphorylated by JNK2 in vivo. Dose-response and time course studies of the effects of heat shock and anisomycin treatment showed a close correlation of the activation of JNK and hyperphosphorylation of HSF1. SB203580 inhibited JNK at the 100 ,M concentration and significantly reduced the amount of hyperphosphorylated HSF1 upon heat shock or anisomycin treatment. SB203580 and dominant-negative JNK suppress hsp70 promoter-driven reporter gene expression selectively at 45°C but not at 42°C heat stress, suggesting that JNK would be preferentially associated with the protective heat shock response against severe heat stress. The possibility that JNK-mediated phosphorylation of HSF1 may selectively stabilize the HSF1 protein and confers protection to cells under conditions of severe stress is discussed. J. Cell. Biochem. 82: 326,338, 2001. © 2001 Wiley-Liss, Inc. [source]

2-oxoglutarate downregulates expression of vascular endothelial growth factor and erythropoietin through decreasing hypoxia-inducible factor-1, and inhibits angiogenesis

JOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2006
Ken Matsumoto
In oxygenated cells, hypoxia-inducible factor-1 (HIF-1) , subunits are rapidly degraded by a mechanism that involves ubiquitination by the von Hippel,Lindau tumor suppressor E3 ligase complex using 2-oxoglutarate as a substrate. We examined the effect of 2-oxoglutarate on the production of erythropoietin and vascular endothelial growth factor (VEGF). The expression of erythropoietin and VEGF protein were dose-dependently downregulated in Hep3B cells by the addition of 2-oxoglutarate. The promoter activity of VEGF-luciferase was dose-dependently downregulated by the addition of 2-oxoglutarate. Gel mobility shift assays revealed that the addition of 2-oxoglutarate dose-dependently inhibited HIF-1 binding activity, but did not affect GATA binding activity. Western blot analysis revealed that 2-oxoglutarate dose-dependently inhibited the HIF-1, protein level in Hep3B cells in hypoxic conditions. However, MG132 (the proteasome inhibitor) rescued the inhibition of HIF-1, protein expression by 2-oxoglutarate. Furthermore, under hypoxic conditions, 2-oxoglutarate dose-dependently inhibited tube formation in in vitro angiogenesis assays. These results indicate that 2-oxoglutarate treatment may be useful for the inhibition of angiogenesis. J. Cell. Physiol. 209: 333,340, 2006. © 2006 Wiley-Liss, Inc. [source]

Adrenoleukodystrophy: subcellular localization and degradation of adrenoleukodystrophy protein (ALDP/ABCD1) with naturally occurring missense mutations

JOURNAL OF NEUROCHEMISTRY, Issue 6 2007
Norimasa Takahashi
Abstract Mutation in the X-chromosomal adrenoleukodystrophy gene (ALD; ABCD1) leads to X-linked adrenoleukodystrophy (X-ALD), a severe neurodegenerative disorder. The encoded adrenoleukodystrophy protein (ALDP/ABCD1) is a half-size peroxisomal ATP-binding cassette protein of 745 amino acids in humans. In this study, we chose nine arbitrary mutant human ALDP forms (R104C, G116R, Y174C, S342P, Q544R, S606P, S606L, R617H, and H667D) with naturally occurring missense mutations and examined the intracellular behavior. When expressed in X-ALD fibroblasts lacking ALDP, the expression level of mutant His-ALDPs (S606L, R617H, and H667D) was lower than that of wild type and other mutant ALDPs. Furthermore, mutant ALDP-green fluorescence proteins (S606L and H667D) stably expressed in CHO cells were not detected due to rapid degradation. Interestingly, the wild type ALDP co-expressed in these cells also disappeared. In the case of X-ALD fibroblasts from an ALD patient (R617H), the mutant ALDP was not detected in the cells, but appeared upon incubation with a proteasome inhibitor. When CHO cells expressing mutant ALDP-green fluorescence protein (H667D) were cultured in the presence of a proteasome inhibitor, both the mutant and wild type ALDP reappeared. In addition, mutant His-ALDP (Y174C), which has a mutation between transmembrane domain 2 and 3, did not exhibit peroxisomal localization by immunofluorescense study. These results suggest that mutant ALDPs, which have a mutation in the COOH-terminal half of ALDP, including S606L, R617H, and H667D, were degraded by proteasomes after dimerization. Further, the region between transmembrane domain 2 and 3 is important for the targeting of ALDP to the peroxisome. [source]

Proteasomal inhibition causes the formation of protein aggregates containing a wide range of proteins, including nitrated proteins

JOURNAL OF NEUROCHEMISTRY, Issue 2 2003
Dong-Hoon Hyun
Abstract Mutations in Cu,Zn-superoxide dismutase (SOD-1) are associated with some familial cases of amyotrophic lateral sclerosis (ALS), but it is not known how they result in cell death. We examined effects of overexpression of wild-type SOD-1 or the G37R or G85R mutations on the accumulation of ubiquitinated and nitrated proteins, and on loss of cell viability induced by the proteasome inhibitor, lactacystin. Wild-type SOD-1 had no effect on proteasomal activity, but the mutants decreased it somewhat. Treatment with lactacystin (1 µm) caused only limited cell viability loss, even though it induced a marked inhibition of proteasomal activities. However, viability loss due to apoptosis was substantial in response to lactacystin when cells were overexpressing a mutant SOD-1. The frequency of cells showing immunoreactivity against ubiquitinated- or nitrated-proteins was enhanced when wild-type and mutant SOD-1 s were overexpressed. Ubiquitinated or nitrated ,-tubulin, SOD-1, ,-synuclein and 68K neurofilaments were observed in the aggregates. Similar aggregates were observed in cells overexpressing mutant parkin (Del3,5, T240R and Q311,X). The nitric oxide synthase inhibitor, l -NAME, decreased viability loss and aggregation, suggesting that nitration of proteins may play an important role in aggregation and in the cell death accompanying it. [source]

Low levels of mutant ubiquitin are degraded by the proteasome in vivo

JOURNAL OF NEUROSCIENCE RESEARCH, Issue 11 2010
Paula van Tijn
Abstract The ubiquitin-proteasome system fulfills a pivotal role in regulating intracellular protein turnover. Impairment of this system is implicated in the pathogenesis of neurodegenerative diseases characterized by ubiquitin- containing proteinaceous deposits. UBB+1, a mutant ubiquitin, is one of the proteins accumulating in the neuropathological hallmarks of tauopathies, including Alzheimer's disease, and polyglutamine diseases. In vitro, UBB+1 properties shift from a proteasomal ubiquitin-fusion degradation substrate at low expression levels to a proteasome inhibitor at high expression levels. Here we report on a novel transgenic mouse line (line 6663) expressing low levels of neuronal UBB+1. In these mice, UBB+1 protein is scarcely detectable in the neuronal cell population. Accumulation of UBB+1 commences only after intracranial infusion of the proteasome inhibitors lactacystin or MG262, showing that, at these low expression levels, the UBB+1 protein is a substrate for proteasomal degradation in vivo. In addition, accumulation of the protein serves as a reporter for proteasome inhibition. These findings strengthen our proposition that, in healthy brain, UBB+1 is continuously degraded and disease-related UBB+1 accumulation serves as an endogenous marker for proteasomal dysfunction. This novel transgenic line can give more insight into the intrinsic properties of UBB+1 and its role in neurodegenerative disease. © 2010 Wiley-Liss, Inc. [source]

Guanosine improves motor behavior, reduces apoptosis, and stimulates neurogenesis in rats with parkinsonism

JOURNAL OF NEUROSCIENCE RESEARCH, Issue 3 2009
Caixin Su
Abstract Parkinson's disease (PD) is characterized by progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc) caused by an abnormal rate of apoptosis. Endogenous stem cells in the adult mammalian brain indicate an innate potential for regeneration and possible resource for neuroregeneration in PD. We previously showed that guanosine prevents apoptosis even when administered 48 hr after the toxin 1-methyl-4-phenylpyridinium (MPP+). Here, we induced parkinsonism in rats with a proteasome inhibitor. Guanosine treatment reduced apoptosis, increased tyrosine hydroxylase,positive dopaminergic neurons and expression of tyrosine hydroxylase in the SNc, increased cellular proliferation in the SNc and subventricular zone, and ameliorated symptoms. Proliferating cells in the subventricular zone were nestin-positive adult neural progenitor/stem cells. Fibroblast growth factor-2-expressing cells were also increased by guanosine. Thus, guanosine protected cells from apoptosis and stimulated "intrinsic" adult progenitor/stem cells to become dopaminergic neurons in rats with proteasome inhibitor,induced PD. The cellular/molecular mechanisms underlying these effects may open new avenues for development of novel therapeutics for PD. © 2008 Wiley-Liss, Inc. [source]

The persisting challenge of selective and specific proteasome inhibition,

JOURNAL OF PEPTIDE SCIENCE, Issue 2 2009
Michael Groll
Abstract Since the discovery of the proteasome and its structure elucidation intensive research programs in academic institutions and pharmaceutical industries led to identification of a wide spectrum of synthetic and natural small proteasomal inhibitors. Activity studies with these small molecules helped to deeply understand the complex biochemical organization and functioning of the proteasome. The new structural and biochemical insights placed the proteasome as an important anti-cancer drug target, as revealed by the dipeptide boronate proteasome inhibitor, bortezomib, which is currently used for treatment of multiple myeloma. Serious side effects and partial cell resistance against bortezomib demand creation and discovery of new improved generations of more specific and potent proteasomal inhibitors. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd. [source]

Interferon-inducible protein IFIX, inhibits cell invasion by upregulating the metastasis suppressor maspin,

MOLECULAR CARCINOGENESIS, Issue 10 2008
Hirohito Yamaguchi
Abstract IFIX,, a member of the interferon-inducible HIN-200 family, has been identified as a putative tumor suppressor. However, the molecular mechanisms underlying IFIX,-mediated tumor suppression are poorly understood. In the present study, we demonstrated that the metastasis suppressor maspin acts as the downstream target of IFIX,. IFIX, suppressed the invasion activity of MDA-MB-468 breast cancer cells, and its inhibitory effect was reversed by the knockdown of maspin. Both Maspin mRNA and protein were upregulated by IFIX,. Histone deacetylase (HDAC) inhibitors, but not DNA methyltransferase inhibitor upregulated maspin, and HDAC1 inhibited the transactivation of maspin promoter. Although the HDAC1 protein was downregulated in IFIX,-expressing cells, IFIX, did not affect HDAC1 mRNA levels. Conversely, a proteasome inhibitor restored the level of HDAC1 protein in IFIX,-expressing cells, and the polyubiqutination of HDAC1 was promoted by IFIX,, suggesting that HDAC1 is regulated by IFIX, through a ubiquitin-proteasome pathway. Together, these data provide novel insights into the tumor-suppressive function of IFIX,. © 2008 Wiley-Liss, Inc. [source]

Phase I study of bortezomib combined with chemotherapy in children with relapsed childhood acute lymphoblastic leukemia (ALL): A report from the therapeutic advances in childhood leukemia (TACL) consortium,

PEDIATRIC BLOOD & CANCER, Issue 2 2010
Yoav Messinger MD
Abstract Background Outcomes remain poor for children after relapse of acute lymphoblastic leukemia (ALL), especially after early marrow relapse. Bortezomib is a proteasome inhibitor with in vitro synergy with corticosteroids and clinical activity in human lymphoid malignancies. Procedure This is a Phase I study of escalating doses bortezomib administered days 1, 4, 8, and 11, added to 4-drug induction chemotherapy with vincristine, dexamethasone, pegylated L -asparaginase, and doxorubicin (VXLD) in children with relapsed ALL. Results Ten patients were enrolled, five in first marrow relapse, and five in second relapse. Four patients were enrolled at dose level 1 (bortezomib 1,mg/m2). One patient was not evaluable for toxicity because of omitted dexamethasone doses. No dose-limiting toxicity (DLT) was observed. Six patients were enrolled at dose level 2 (bortezomib 1.3,mg/m2). One patient had dose-limiting hypophosphatemia and rhabdomyolysis after 1 dose of bortezomib, and died from a diffuse zygomyces infection on day 17. Five additional patients were enrolled with no subsequent DLTs. As planned, no further dose escalation was pursued. The regimen had predictable toxicity related to the chemotherapy drugs. Two patients had mild peripheral neuropathy (grades 1 and 2). Six of nine evaluable patients (67%) achieved a complete response (CR), and one had a bone marrow CR with persistent central nervous system leukemia. Conclusions The combination of bortezomib (1.3,mg/m2) with VXLD is active with acceptable toxicity in pretreated pediatric patients with relapsed ALL. We are expanding the 1.3,mg/m2 cohort for a phase II estimate of response. Study registered at ClinicalTrials.gov (http://clinicaltrials.gov/ct2/show/NCT00440726). Pediatr Blood Cancer 2010;55:254,259. © 2010 Wiley-Liss, Inc. [source]

Proteasome Inhibition Causes Apoptosis of Normal Human Plasma Cells Preventing Alloantibody Production

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 1 2009
D. K. Perry
Antibody production by normal plasma cells (PCs) against human leukocyte antigens (HLA) can be a major barrier to successful transplantation. We tested four reagents with possible activity against PCs (rituximab, polyclonal rabbit antithymocyte globulin (rATG), intravenous immunoglobulin (IVIG) and the proteasome inhibitor, bortezomib) to determine their ability to cause apoptosis of human bone marrow-derived PCs and subsequently block IgG secretion in vitro. IVIG, rituximab and rATG all failed to cause apoptosis of PCs and neither rituximab nor rATG blocked antibody production. In contrast, bortezomib treatment led to PC apoptosis and thereby blocked anti-HLA and antitetanus IgG secretion in vitro. Two patients treated with bortezomib for humoral rejection after allogeneic kidney transplantation demonstrated a transient decrease in bone marrow PCs in vivo and persistent alterations in alloantibody specificities. Total IgG levels were unchanged. We conclude that proteasome activity is important for PC longevity and its inhibition may lead to new techniques of controlling antibody production in vivo. [source]

Lack of nigrostriatal pathology in a rat model of proteasome inhibition

ANNALS OF NEUROLOGY, Issue 2 2006
Amy B. Manning-Bo
Systemic administration of ubiquitin-proteasome system inhibitors to rodents has been reported to induce certain behavioral and neuropathological features of Parkinson's disease. The goal of this study was to replicate these observations by administering a proteasome inhibitor (PSI) to rats using McNaught and colleagues' protocol. No alterations in locomotor activity or striatal dopamine and its metabolites were observed. Differences in nigral dopaminergic cell number between proteasome inhibitor, and vehicle-treated rats and inclusion bodies were not found. Extending the time of survival after administration and using different solvents failed to alter results, indicating this proteasome inhibitor does not consistently produce the selective toxicity and pathological hallmarks characterizing Parkinson's disease. Ann Neurol 2006;60:256,260 [source]

Proteasome inhibition and Parkinson's disease modeling

ANNALS OF NEUROLOGY, Issue 2 2006
Jordi Bové PhD
Impaired proteasome function is a potential mechanism for dopaminergic neuron degeneration. To model this molecular defect, we administered systemically the reversible lipophilic proteasome inhibitor, carbobenzoxy- L -isoleucyl-,-t-butyl- L -glutamyl- L -alanyl- L -leucinal (PSI), to rodents. In contrast to a previous report, this approach failed to cause any detectable behavioral or neuropathological abnormality in either rats or mice. Although theoretically appealing, this specific model of Parkinson's disease appears to exhibit poor reproducibility. Ann Neurol 2006;60:260,264 [source]

Receptor activator of NF-,B ligand, macrophage inflammatory protein-1,, and the proteasome

CANCER, Issue S3 2003
Novel therapeutic targets in myeloma
Abstract BACKGROUND The bone destruction in myeloma patients is largely responsible for the clinical features of the disease. However, only recently has attention focused on identifying and developing drugs targeted specifically at the osteolysis. Receptor activator of NF-,B ligand (RANKL), macrophage inflammatory protein (MIP)-1,, and proteasomal function have been implicated in the pathogenesis of myeloma and associated bone disease. We provide "proof of principle" in preclinical myeloma models that these are indeed valid molecular targets in development of novel therapeutics. METHODS The efficacy of antagonists of RANKL and MIP-1, bioactivities (RANK.Fc and neutralizing monoclonal anti-MIP-1, antibody) in ameliorating osteolysis and reducing tumor burden was evaluated in a mouse model in which murine myeloma 5TGM1 cells are injected intravenously into syngeneic mice. In addition, the activity of a petidyl aldehyde proteasome inhibitor (proteasome inhibitor-1 [PSI]) on tumor growth was tested in a murine 5TGM1 plasmacytoma model and in mice intravenously inoculated with 5TGM1 cells. RESULTS RANK.Fc and anti-MIP-1, antibody inhibited the development and progression of osteolytic lesions and significantly reduced tumor load assessed by serum monoclonal paraprotein titers. Intratumoral injections of PSI inhibited growth of 5TGM1 plasmacytomas and induced tumor regression in some cases. In addition, systemic administration of PSI significantly prolonged time to onset of paraplegia in tumor-bearing mice. CONCLUSIONS The results highlight the critical roles of RANKL and MIP-1, in the development and progression of myeloma and provide a basis for future evaluation in myeloma patients of novel therapeutics that disrupt interactions of RANKL and MIP-1, with their cognate receptors. The data also suggest that further studies in preclincal myeloma models aimed at identifying other proteasome inhibitors with antitumor efficacy would be worthwhile. Cancer 2003;97(3 Suppl):813,7. © 2003 American Cancer Society. DOI 10.1002/cncr.11133 [source]

Hypertonic upregulation of betaine transport in renal cells is blocked by a proteasome inhibitor

CELL BIOCHEMISTRY AND FUNCTION, Issue 5 2005
Philip E. Lammers
Abstract The renal betaine transporter (BGT1) protects cells in the hypertonic medulla by mediating uptake and accumulation of the osmolyte betaine. Transcription plays an essential role in upregulating BGT1 transport in MDCK cells subjected to hypertonic stress. During hypertonic stress, the abundance of the transcription factor TonEBP increases and it shifts from the cytoplasm to the nucleus where it activates transcription of the BGT1 gene. Little is known about post-transcriptional regulation of BGT1 protein. In the presence of the proteasome inhibitor MG-132, which blocked nuclear translocation of TonEBP, the hypertonic upregulation of BGT1 protein and transport was prevented and cell viability in hypertonic medium was impaired over 24,h. Urea also prevented the hypertonic upregulation of BGT1 protein and transport, but did not interfere with TonEBP translocation and cell viability. Shorter treatments of hypertonic cells with MG-132 avoided viability problems and produced dose-dependent inhibition of translocation and transport. When stably transfected MDCK cells that over-expressed BGT1 were treated for 6,h with hypertonic medium containing 3,µM MG-132, there was 43% inhibition of nuclear translocation, 83% inhibition of BGT1 transport, and no change in viability. While other proteasome functions may be involved, these data are consistent with a critical role for nuclear translocation of TonEBP in upregulation and membrane insertion of BGT1 protein. Copyright © 2005 John Wiley & Sons, Ltd. [source]

2133: p62/sequestosome 1 as a regulator of proteasome inhibitor-induced autophagy in human retinal pigment epithelial cells

ACTA OPHTHALMOLOGICA, Issue 2010
K KAARNIRANTA
Purpose The pathogenesis of age-related macular degeneration involves impaired protein degradation in retinal pigment epithelial (RPE) cells. The ubiquitin-proteasome pathway and the lysosomal pathway including autophagy are the major proteolytic systems in eukaryotic cells. Prior to proteolysis, heat shock proteins (HSPs) attempt to refold stress ,induced misfolded proteins and thus prevent the accumulation of cytoplasmic protein aggregates. The functional roles of p62 and HSP70 were evaluated in conjunction with protesome inhibitor -induced autophagy in human RPE cells (ARPE-19). Methods The p62, HSP70 and ubiquitin protein levels and localization were analyzed by Western blotting and immunofluorescense. Confocal and transmission electron microscopy were used to detect cellular organelles and to evaluate the morphological changes. The p62 and HSP70 levels were modulated using RNA interference and overexpression techniques. Cell viability was measured by colorimetric assay. Results Proteasome inhibition evoked the accumulation of p62 and HSP70 that strongly co-localized with each other in perinuclear aggregates. The p62 accumulation was time and concentration dependent after MG-132 proteasome inhibitor loading. Interestingly, autophagy induction was p62 and Hsp70 independent. In addition, the p62 silencing decreased the ubiquitination level of the perinuclear aggregates. Recently we showed that hsp70 mRNA depletion increased cell death in ARPE-19 cells. Here we now demonstrate that p62 mRNA silencing has similar effects on cellular viability. Conclusion The p62 and HSP70 are central molecules in the regulation of protein turnover in human retinal pigment epithelial cells in proteasome inhibitor- induced autophagy. [source]

2135: Influence of Hsp90 and HDAC inhibition and tubulin acetylation on perinuclear protein aggregation in human retinal pigment epithelial cells

ACTA OPHTHALMOLOGICA, Issue 2010
K KAARNIRANTA
Purpose Retinal pigment epithelial (RPE) cells are continually exposed to oxidative stress that contributes to protein misfolding, aggregation and functional abnormalities during aging. The protein aggregates formed at the cell periphery are delivered along the microtubulus network by dynein dependent retrograde trafficking to a juxtanuclear location. Methods Cellular organelles were analysed by transmission electron microscopy of ARPE-19 cells exposed 5 µM MG-132, 0.25 µM geldanamycin (GA), 1 µM trichostatin A (TSA), 1 µM taxol (TAX) or 5 µM nocodazole (NOC) for 24 hours. In addition, the cells were treated simultaneously with GA or TSA or TAX or NOC and MG-132 up to 24 hours. Ubiquitin, Hsp90, Hsp70, acetylated tubulin and Hsc70 protein levels were analyzed by western blotting. Results Hsp90 inhibition by geldanamycin can effectively suppress proteasome inhibitor, MG-132 ,induced protein aggregation in a way that is an independent of HDAC inhibition, or the tubulin acetylation levels in ARPE-19 cells. However, the tubulin acetylation and polymerization state affects the localization of the proteasome-inhibitor ,induced aggregation. Conclusion Hsp90 inhibition is effectively related to regulation of protein aggregation that is independent of HDAC inhibition or tubulin acetylation levels in the RPE cells. Our findings open new perspectives for understanding the pathogenesis of protein aggregation in retinal cells and can be useful for the development of therapeutic treatments to prevent retinal cell deterioration. [source]

Dendritic growth induced by BMP-7 requires Smad1 and proteasome activity

DEVELOPMENTAL NEUROBIOLOGY, Issue 2 2001
Xin Guo
Abstract Bone morphogenetic proteins (BMPs) induce dendritic growth in cultured sympathetic neurons; however, the signaling pathways that mediate this dendrite-promoting activity have not been previously characterized. Here we report studies of the signaling events that regulate the growth of these afferent processes. We find that Smad1 is expressed in sympathetic neurons and that BMPs rapidly induce its phosphorylation and translocation from the cytoplasm to the nucleus. Furthermore, a dominant negative form of Smad1 inhibits BMP-7-induced dendritic growth, suggesting a requirement for Smad1 activation in this biological activity of BMP-7. A physical interaction between Smad1 and components involved in the proteasome-mediated degradation system was detected with a yeast two-hybrid screen, thereby prompting an examination of the effects of proteasome inhibitors on dendritic growth. Lactacystin and ALLN (N -acetyl-Leu-Leu-norleucinal) selectively blocked BMP-7-induced dendritic growth without adversely affecting either cell viability or axonal growth. Moreover, studies of transfected P19 cells suggest that the proteasome inhibitors directly block the effects of Smad1 on the transcriptional activity of the Tlx-2 promoter. These data indicate that BMP-induced dendritic growth requires Smad1 activation and involves proteasome-mediated degradation events. © 2001 John Wiley & Sons, Inc. J Neurobiol 48: 120,130, 2001 [source]

Update on therapeutic options in Waldenström macroglobulinemia

EUROPEAN JOURNAL OF HAEMATOLOGY, Issue 1 2009
Xavier Leleu
Abstract Waldenström macroglobulinemia (WM) is a B-cell disorder characterized primarily by bone marrow infiltration with lymphoplasmacytic cells (LPCs), along with demonstration of an IgM monoclonal gammopathy in the blood. WM remains incurable, with 5,6 yr median overall survival for patients with symptomatic WM. The main therapeutic options include alkylating agents, nucleoside analogues, and rituximab, either in monotherapy or in combination. Studies involving combination chemotherapy are ongoing, and preliminary results are encouraging. However, there are several limitations to these approaches. The complete response rate is low and the treatment free survival are short in many patients, no specific agent or regimen has been shown to be superior to another, and no treatment has been specifically approved for WM. As such, novel therapeutic agents are needed for the treatment of WM. In ongoing efforts, we and others have sought to exploit advances made in the understanding of the biology of WM so as to develop new targeted therapeutics for this malignancy. These efforts have led to the development of proteasome inhibitors, of them bortezomib, several Akt/mTor inhibitors, such as perifosine and Rad001, and immunomodulatory agents such as thalidomide and lenalidomide. Many agents and monoclonal antibodies are currently being tested in clinical trials and seem promising. This report provides an update of the current preclinical studies and clinical efforts for the development of novel agents in the treatment of WM. [source]