In Vitro and In Vivo Proteasome Activity Profiles of Bortezomib and a Novel Proteasome Inhibitor NPI-0052.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3363-3363 ◽  
Author(s):  
Dharminder Chauhan ◽  
Ta-Hsiang Chao ◽  
Laurence Catley ◽  
Benjamin Nicholson ◽  
Mugdha Velanker ◽  
...  
Keyword(s):  
Proteasome Inhibitor ◽  
Proteasome Inhibitors ◽  
Proteasome Inhibition ◽  
Proteasome Activity ◽  
Catalytic Activities ◽  
Proteasome Subunits ◽  
20 Nm ◽  
Whole Blood Cells

Abstract Proteasome inhibition is an effective anti-cancer therapy. Proteasome function is mediated by three catalytic activities: chymotrypsin-like (CT-L), trypsin-like (T-L), and caspase-like (C-L). Kinetics of inhibition of catalytic activities may define the pharmacologic utility of proteasome inhibitors. Here we utilized two structurally distinct proteasome inhibitors Bortezomib, a dipeptide boronic acid; and a non-peptide proteasome inhibitor NPI-0052 to determine their effect on proteasome activities in vitro and in animal model. Examination of the proteasome activity using human erythrocyte 20S proteasomes and fluorogenic substrates shows that NPI-0052 and Bortezomib inhibit all three proteasome activities, albeit at different concentrations: NPI-0052 inhibits CT-L and T-L activities at lower concentrations than Bortezomib (NPI-0052: EC50 = 3.5 ± 0.3 nM versus Bortezomib: 7.9 ± 0.5 nM for CT-L activity; and NPI-0052: EC50 = 28 ± 2 nM versus Bortezomib: EC50 = 590 ± 67 nM for T-L activity); in contrast, higher concentrations of NPI-0052 than Bortezomib are required to inhibit C-L activity (NPI-0052 EC50 = 430 ± 34 nM versus Bortezomib: EC50 = 53 ± 10 nM for C-L activity). We next compared the effects of NPI-0052 and Bortezomib on all three proteasome activities in vivo. Mice were treated with a single MTD dose of NPI-0052 (0.15 mg/kg i.v) or Bortezomib (1 mg/kg i.v); blood samples were collected at 90 mins, 24h, 48h, 72h, or 168h; and whole blood cells were then analyzed for proteasome activity. NPI-0052 completely inhibited CT-L activity by 90 mins, which was recoverable by 168h; whereas Bortezomib-inhibited CT-L activity is recoverable at 24h. T-L activity is significantly inhibited by NPI-0052 at 90 mins, 24h, 48h, and 72h; and is recoverable by 168h; in contrast, Bortezomib enhances T-L activity. Finally, NPI-0052 inhibits C-L activity at 90 mins, 24h, 48h, and 72h; and this activity recovered at 168h, whereas Bortezomib significantly inhibits C-L activity at 90 mins, 24h, 48h, and 72h; and is similarly recoverable at 168h. We next utilized a novel methodology to measure proteasome activity by immunoblotting using dansylAhx3L3VS as a probe (Berkers et al., Nature Methods, 2005), which also allow for determining subunit specificity of a proteasome inhibitor. Multiple myeloma (MM) cells were cultured in the presence or absence of various concentrations of either NPI-0052 (2 nM; 7 nM: IC50; or 20 nM) or Bortezomib (2 nM; 5 nM: IC50; or 20 nM). Competition experiments between either NPI-0052 or Bortezomib and dansylAhx3L3VS revealed that NPI-0052 (7 nM) markedly inhibits the CT-L activity represented by beta-5 subunit of the proteasome and decreased the dansylAhx3L3VS-labeling of the beta-1 (C-L activity) and -2 (T-L activity) subunits. Slightly higher concentrations of Bortezomib are necessary to markedly inhibit beta-5 and -1 subunits, whereas beta-2 subunits are not inhibited. Importantly, both agents trigger apoptosis in MM cells; however, NPI-0052 is remarkably less toxic to normal lymphocytes than Bortezomib. Our data show that NPI-0052, like Bortezomib, targets the proteasome, but triggers a proteasome activity profile distinct from Bortezomib. The mechanistic insights gained from these studies will allow for improved drug design based on targeting specific proteasome subunits.

scholarly journals Proteasome inhibition as a therapeutic approach in atypical teratoid/rhabdoid tumors

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Andrew Morin ◽  
Caroline Soane ◽  
Angela Pierce ◽  
Bridget Sanford ◽  
Kenneth L Jones ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Cell Lines ◽  
Proteasome Inhibitor ◽  
High Grade Glioma ◽  
Proteasome Inhibition ◽  
Atypical Teratoid ◽  
Rhabdoid Tumors ◽  
Approved Drugs

Abstract Background Atypical teratoid/thabdoid tumor (AT/RT) remains a difficult-to-treat tumor with a 5-year overall survival rate of 15%–45%. Proteasome inhibition has recently been opened as an avenue for cancer treatment with the FDA approval of bortezomib (BTZ) in 2003 and carfilzomib (CFZ) in 2012. The aim of this study was to identify and characterize a pre-approved targeted therapy with potential for clinical trials in AT/RT. Methods We performed a drug screen using a panel of 134 FDA-approved drugs in 3 AT/RT cell lines. Follow-on in vitro studies used 6 cell lines and patient-derived short-term cultures to characterize selected drug interactions with AT/RT. In vivo efficacy was evaluated using patient derived xenografts in an intracranial murine model. Results BTZ and CFZ are highly effective in vitro, producing some of the strongest growth-inhibition responses of the evaluated 134-drug panel. Marizomib (MRZ), a proteasome inhibitor known to pass the blood–brain barrier (BBB), also strongly inhibits AT/RT proteasomes and generates rapid cell death at clinically achievable doses in established cell lines and freshly patient-derived tumor lines. MRZ also significantly extends survival in an intracranial mouse model of AT/RT. Conclusions MRZ is a newer proteasome inhibitor that has been shown to cross the BBB and is already in phase II clinical trials for adult high-grade glioma (NCT NCT02330562 and NCT02903069). MRZ strongly inhibits AT/RT cell growth both in vitro and in vivo via a moderately well-characterized mechanism and has direct translational potential for patients with AT/RT.

scholarly journals Mechanistic Insights into the Enhancement of Adeno-Associated Virus Transduction by Proteasome Inhibitors

2013 ◽  
Vol 87 (23) ◽  
pp. 13035-13041 ◽  
Author(s):  
Angela M. Mitchell ◽  
R. Jude Samulski
Keyword(s):  
Cysteine Protease ◽  
Proteasome Inhibitor ◽  
Proteasome Inhibitors ◽  
Proteasome Inhibition ◽  
Proteasome Activity ◽  
Protease Inhibition ◽  
Adeno Associated Virus

Proteasome inhibitors (e.g., bortezomib, MG132) are known to enhance adeno-associated virus (AAV) transduction; however, whether this results from pleotropic proteasome inhibition or off-target serine and/or cysteine protease inhibition remains unresolved. Here, we examined recombinant AAV (rAAV) effects of a new proteasome inhibitor, carfilzomib, which specifically inhibits chymotrypsin-like proteasome activity and no other proteases. We determined that proteasome inhibitors act on rAAV through proteasome inhibition and not serine or cysteine protease inhibition, likely through positive changes late in transduction.

Neurodegeneration Induced by Bortezomib Exposure in Vitro Occurs Via Proteasome Independent Mechanisms.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2859-2859
Author(s):  
Shirin Arastu-Kapur ◽  
Andrew J. Ball ◽  
Janet L. Anderl ◽  
Mark K Bennett ◽  
Christopher J Kirk
Keyword(s):  
Peripheral Nerve ◽  
Proteasome Inhibitor ◽  
Serine Proteases ◽  
Proteasome Inhibitors ◽  
Proteasome Inhibition ◽  
Nerve Degeneration ◽  
Differentiated Cells ◽  
Favorable Safety ◽  
Neurite Degeneration

Abstract Abstract 2859 Poster Board II-835 BACKGROUND: The dipeptide boronate proteasome inhibitor bortezomib (BTZ; Velcade®) is approved for the treatment of multiple myeloma and non-Hodgkin's lymphoma. Bortezomib-induced peripheral neuropathy (BIPN, Blood (2008)112:1593-1599) is seen in ∼30% of BTZ-treated patients and can result in dose reductions and discontinuations that may result in suboptimal levels of proteasome inhibition. Carfilzomib (CFZ), a tetrapeptide epoxyketone, is a selective and irreversible proteasome inhibitor that is structurally and mechanistically distinct from bortezomib. Single agent treatment with CFZ has demonstrated strong activity in relapsed and refractory myeloma and a favorable safety profile in Phase 2 trials (ASH2008:864 & 865). Importantly treatment-emergent PN was seen at low levels and did not result in dose modifications or discontinuations. The disparate safety data for these proteasome inhibitors suggest that non-proteasomal mechanisms may underlie BIPN. Using activity-based probes in peripheral blood mononuclear cell (PBMC) lysates, we previously demonstrated inhibition of non-proteasomal proteases by BTZ and other proteasome inhibitors with a boronate pharmacophore (EHA2009:0939). However, the involvement of the proteasome in the peripheral nerve degeneration and BIPN in BTZ-treated myeloma patients remains to be established. AIMS: To establish an in vitro model of peripheral nerve degeneration and to determine the effects of proteasome inhibition by BTZ and CFZ on neurite outgrowth and cell survival. METHODS: SH-SY5Y neuroblastoma cells were differentiated by long term culture in retinoic acid and brain derived nerve growth factor to induce neurite outgrowth. The effects of proteasome inhibitors were measured by high content image analysis of fluorescent images for cell survival (Hoechst nuclear counterstain) and neurite degeneration (FITC-mouse anti-beta-III-tubulin). Phase contrast images were also collected to observe morphological effects and gross cell death. Cell viability and proteasome inhibition was measured in undifferentiated and differentiated cells. The MEROPS (peptidase) database was mined for candidate serine proteases with a P1 selectivity of Leu/Phe/Tyr to identify candidate off-targets CFZ and BTZ and candidate proteases were validated by standard biochemical and cell biology techniques. RESULTS: In differentiated SH-SY5Y cells, the average neurite length decreased by 33% following 24 hr exposure to 10nM BTZ but was unaffected by the same concentration of CFZ. Proteasome inhibition as determined by a fluorescent substrate for the chymotrypsin-like activity was equivalent (∼70%) after a 24 hr exposure for both compounds in differentiated cells, suggesting that neurodegeneration involves non-proteasomal pathways. With 72 hrs continuous exposure, BTZ was 10-fold more potent than CFZ at inducing neurodegeneration. Furthermore, in both undifferentiated and differentiated SH-SY5Y cells, BTZ was 5-fold more cytotoxic than CFZ. Database mining for serine proteases with a selectivity for Leu/Phe/Tyr at P1 was used to identify other potential BTZ targets that might underlie neurotoxicity. One candidate is HtrA2 (also called Omi), an inducible mitochondrial serine protease whose activity protects neurons from stress induced apoptosis (Hum Mol Genet (2005) 14(5):2099-2111). HtrA2 levels increased 2-fold in SH-SY5Y cells treated with either BTZ or CFZ for 6 hrs at 40 nM. Using a gel based assay and purified enzyme preparations, BTZ inhibited HtrA2 activity with an IC50 ∼ 4 nM, equivalent to its activity against the proteasome. In contrast, Carfilzomib did not inhibit HtrA2 at the highest concentration tested (10 mM). CONCLUSIONS: These data demonstrate that BTZ induces neuronal cell death and neurite degeneration in vitro by proteasome-independent mechanisms. We propose that combined inhibition of the proteasome and HtrA2 by BTZ may underlie peripheral nerve toxicities in vitro and may be involved in BIPN in myeloma patients. In this model, CFZ, which mediates equivalent proteasome inhibition to BTZ in neurons, does not induce neurodegeneration due to inactivity against HtrA2. Future profiling of non-proteasomal targets of BTZ, including HtrA2 activity, in patient samples is merited. These results suggest that the favorable safety profile of CFZ in myeloma patients may be a result of its high selectivity for proteasomal proteases. Disclosures: Arastu-Kapur: Proteolix, Inc: Employment. Ball:Millipore Corp: Employment. Anderl:Millipore Corp: Employment. Bennett:Proteolix: Employment. Kirk:Proteolix, Inc: Employment.

The Novel Proteasome Inhibitors Carfilzomib and Oprozomib Induce Milder Degenerative Effects Compared To Bortezomib When Administered Via Oral Feeding In An In Vivo Drosophila Experimental Model: A Biological Platform To Evaluate Safety/Efficacy Of Proteasome Inhibitors

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1930-1930
Author(s):  
Evangelos Terpos ◽  
Eleni N. Tsakiri ◽  
Efstathios Kastritis ◽  
Tina Bagratuni ◽  
Vassilis G. Gorgoulis ◽  
...  
Keyword(s):  
Oral Administration ◽  
Proteasome Inhibitor ◽  
Germ Line ◽  
Conflicts Of Interest ◽  
Proteasome Inhibitors ◽  
Proteasome Inhibition ◽  
Somatic Tissue ◽  
Oral Feeding ◽  
Somatic Tissues

Abstract The proteasome is involved in the degradation of both normal, short-lived ubiquitinated proteins and mutated or damaged proteins. Carfilzomib is a tetrapeptide epoxyketone–based proteasome inhibitor and oprozomib is an orally bioavailable tripeptide epoxyketone-based proteasome inhibitor. The primary target for both agents is the chymotrypsin-like β5 subunit of the constitutive proteasome and immunoproteasome. Oprozomib is 5-fold less potent than carfilzomib, but displays similar cytotoxic potential with longer exposure times due to its time-dependent proteasome inhibition. In contrast, bortezomib is a slowly reversible proteasome inhibitor with potency of proteasome inhibition similar to carfilzomib. We propose the fruit fly Drosophila melanogaster as an in vivo platform for screening and characterizing proteasome inhibitors at the whole organism level. Drosophilais well-suited to this line of investigation, due to its powerful genetics, its similarities in key metabolic and aging pathways with humans, the fact that it expresses proteasomes that structurally resemble those from mammals, and also because it comprises a soma-germ line demarcation composed of both post-mitotic and mitotic cells. Moreover, flies live for few months and thus, drug screening on large cohorts can be completed in a reasonable time. We validate our model by investigating the effects of orally administered carfilzomib and oprozomib vs. bortezomib. In isolated Drosophila proteasome in vitroassays, carfilzomib showed a pattern of inhibitory activity similar to bortezomib, whereas oprozomib was less effective. After continuous oral administration of the inhibitors (∼50 μM of carfilzomib and ∼300-400 μM of oprozomib) to young flies (by adding the inhibitor in the flies’ culture medium) a proteasome inhibitory effect in somatic tissues roughly similar to 1 μM bortezomib was induced. Similar findings were noted when we analyzed distinct somatic tissue parts (i.e., head, thorax and abdomen), indicating that orally administered proteasome inhibitors are equally distributed to different body parts. As in the case of bortezomib, the effects of the inhibitors were less pronounced in the reproductive tissues. At the molecular level, carfilzomib (as compared to bortezomib) induced a milder disruption of fly somatic tissue proteostasis, lower rates of somatic tissue oxidative stress and less intense activation of genomic antioxidant response elements that correlated with reduced intensities of proteasome genes and protein subunit upregulation. Proteasome subunit induction was found to depend on the activity of the transcription factor Nrf2, a master regulator of cellular anti-oxidant responses. Furthermore, carfilzomib promoted the induction of lysosomal enzymes (e.g. cathepsins) and autophagy-related genes but less intensively compared to bortezomib. At concentrations that induced rates of proteasome inhibition that were similar to bortezomib, there were no significant toxic effects of either carfilzomib or oprozomib to oogenesis or to embryogenesis. Compared to bortezomib, both inhibitors exerted a significantly milder impact on the neuromusculatory system (locomotor performance) of the flies. Finally, we found that sustained oral administration of either carfilzomib or oprozomib exerted significantly milder effects (as compared to bortezomib) on flies’ mortality rate, healthspan and overall longevity. Our in vivo data support that carfilzomib is significantly less toxic compared to bortezomib, including neuromusculatory toxicity. Oprozomib was also less toxic but it is worth noting that it showed reduced activity against fly proteasomes. In support, our preliminary analyses indicated that in comparison to bortezomib and carfilzomib, oprozomib was less potent when tested in human osteosarcoma cancer cell lines. The validity of our in vivo pharmacological model is exemplified by the observed similarities with the reported clinical adverse effects, while the ratio of the different doses used to achieve similar rates of proteasome inhibition in Drosophila somatic tissues (i.e. ∼1 μM bortezomib, ∼50 μM carfilzomib) is reminiscent of the doses used in the clinic (i.e. ∼1.3 mg/m2 bortezomib and ∼25-56 mg/m2 carfilzomib). We conclude that fruit flies represent a valid biological platform for evaluating the efficacy and toxicity of proteasome inhibitors. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Development of noninvasive biomarkers of response to proteasome inhibitor therapy (ixazomib) by imaging disrupted protein homeostasis in mouse models of solid tumors

2017 ◽  
Author(s):  
Yanan Zhu ◽  
Rajiv Ramasawmy ◽  
Sean Peter Johnson ◽  
Valerie Taylor ◽  
Alasdair Gibb ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Solid Tumors ◽  
Proteasome Inhibitor ◽  
Chemical Exchange ◽  
Proteasome Inhibitors ◽  
Surrogate Marker ◽  
Standard Of Care ◽  
Proteasome Inhibition ◽  
Protein Homeostasis

AbstractWith clinically-approved proteasome inhibitors now a standard of care for multiple myeloma, and increasing interest in their use in solid tumors, methods for monitoring therapeutic response in vivo are critically required. Here, we show that tumor protein homeostasis can be noninvasively monitored, using chemical exchange (CEST) magnetic resonance imaging (MRI) as a surrogate marker for proteasome inhibition, alongside diffusion MRI and relaxometry. We show that the in vivo CEST signal associated with amides and amines increases in proportion to proteasome inhibitor dose (ixazomib) and the magnitude of therapeutic effect in colorectal cancer xenografts. Moreover, we show that SW1222 and LS174T human colorectal cancer cell lines demonstrate differing sensitivities to ixazomib, which was reflected in our MRI measurements. We also found evidence of a mild stimulation in tumor growth at low ixazomib doses. Our results therefore identify CEST MRI as a promising method for safely and noninvasively monitoring changes in tumor protein homeostasis.

S-2209, a Novel, Non-Boronic Proteasome Inhibitor, Induces Apoptosis and Cell Growth Arrest in Multiple Myeloma Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1513-1513
Author(s):  
Philipp Baumann ◽  
Karin Mueller ◽  
Sonja Mandl-Weber ◽  
Helmut Ostermann ◽  
Ralf Schmidmaier ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Growth ◽  
Cell Lines ◽  
Proteasome Inhibitor ◽  
Wistar Rats ◽  
Proteasome Inhibitors ◽  
Proteasome Inhibition ◽  
Inhibition Assay ◽  
Induction Of Apoptosis

Abstract Purpose: Multiple Myeloma (MM) is still an incurable disease. Patients become resistant to cytotoxic drugs and die of disease progression. Bortezomib is the first approved member of a new class of antineoplastic agents, the proteasome inhibitors. It has synergistic effects with genotoxic drugs and steroids in vitro and in vivo. However, single agent activity in humans is only moderate and specific toxicity (e.g. neurotoxicity) often limits its clinical use. Further proteasome inhibitors need to be developed to optimize this promising treatment option. Methods: The new proteasome inhibitor S-2209 was characterized by several assays. Inhibition of the chymotryptic activity of the human 20S proteasome was determined with the in-vivo protease inhibition assay. Additionally, proteasome inhibition was determined in isolated PBMCs from S2209-pretreated wistar rats. Inhibition of NFκB activity was determined using a NFκB reporter gene assay. Cell growth rates of MM cells (OPM-2, U266, RPMI-8226 and NCI-H929) were measured with the WST-1 assay. Induction of apoptosis was shown by flow cytometry after staining with annexin-V-FITC and propidium iodide. Intracellular signal modulation was demonstrated by western blotting. Toxicity of the substance was tested in male wistar rats. Results: The proteasome inhibition assay revealed an IC50 at ∼220nM. The NFκB inhibition assay using an A549-NFκB-SEAP transfected cell line showed an EC50 of 0.9μM. Upon incubation with S-2209, cell growth as well as cell proliferation in MM cell lines was significantly inhibited (IC50 100nM – 600nM). Furthermore, the incubation with S-2209 resulted in strong induction of apoptosis in all four MM cell lines even at nanomolar concentrations (IC50 at ∼300nm) as well as primary cells. Western blotting revealed caspase-3 cleavage and upregulon of p53 and increased phosphorylation of IκB. No induction of apoptosis was detected in PBMCs from healthy humans. Despite the administration of 5, 10 or 15mg/kg/day in wistar rats, no toxicity with respect to body weight, hepatic enzymes (ALAT ASAT, ALP), creatinin or hemoglobin was seen. Proteasome inhibition in white blood cells isolated from the treated rats was higher in the S-2209 treated animals than in control animals treated with 0.1mg/kg/d bortezomib (89% vs. 70% respectively). Conclusions: The proteasome inhibitor S-2209 inhibitis MM cell growth and induces apoptosis. This is accompanied by a strong inhibition of proteasome and of the NFκB activity. Because S-2209 shows a favourable toxicity profile in vivo, further clinical development of this promising drug is urgently needed.

scholarly journals FoxO1 Is a Novel Regulator of 20S Proteasome Subunits Expression and Activity

2021 ◽  
Vol 9 ◽  
Author(s):  
Marianna Kapetanou ◽  
Tobias Nespital ◽  
Luke S. Tain ◽  
Andre Pahl ◽  
Linda Partridge ◽  
...  
Keyword(s):  
Proteasome Activity ◽  
20S Proteasome ◽  
Direct Role ◽  
Forkhead Box ◽  
Age Related ◽  
Proteasome Subunits ◽  
Rate Limiting

Proteostasis collapses during aging resulting, among other things, in the accumulation of damaged and aggregated proteins. The proteasome is the main cellular proteolytic system and plays a fundamental role in the maintenance of protein homeostasis. Our previous work has demonstrated that senescence and aging are related to a decline in proteasome content and activities, while its activation extends lifespan in vitro and in vivo in various species. However, the mechanisms underlying this age-related decline of proteasome function and the down-regulation in expression of its subunits remain largely unclear. Here, we demonstrate that the Forkhead box-O1 (FoxO1) transcription factor directly regulates the expression of a 20S proteasome catalytic subunit and, hence, proteasome activity. Specifically, we demonstrate that knockout of FoxO1, but not of FoxO3, in mice severely impairs proteasome activity in several tissues, while depletion of IRS1 enhances proteasome function. Importantly, we show that FoxO1 directly binds on the promoter region of the rate-limiting catalytic β5 proteasome subunit to regulate its expression. In summary, this study reveals the direct role of FoxO factors in the regulation of proteasome function and provides new insight into how FoxOs affect proteostasis and, in turn, longevity.

Proteasome Inhibitors Induce Apoptosis in Glucocorticoid-Resistant Chronic Lymphocytic Leukemic Lymphocytes

Blood ◽  
1998 ◽  
Vol 92 (11) ◽  
pp. 4220-4229 ◽  
Author(s):  
Joya Chandra ◽  
Irina Niemer ◽  
Joyce Gilbreath ◽  
Kay-Oliver Kliche ◽  
Michael Andreeff ◽  
...  
Keyword(s):  
Dna Fragmentation ◽  
Proteasome Inhibitor ◽  
Transmembrane Potential ◽  
Proteasome Inhibitors ◽  
Nucleoside Analogs ◽  
Proteasome Inhibition ◽  
Conventional Chemotherapy ◽  
Partial Sequencing ◽  
Biochemical Mechanisms

Abstract Our previous work showed that the nuclear scaffold (NS) protease is required for apoptosis of both thymocytes and chronic lymphocytic leukemic (CLL) lymphocytes. Because partial sequencing of one of the subunits of the NS protease revealed homology to the proteasome, we tested the effects of classical proteasome inhibitors on apoptosis in CLL cells. Here we report that proteasome inhibition caused high levels of DNA fragmentation in all patients analyzed, including those resistant to glucocorticoids or nucleoside analogs, in vitro. Proteasome inhibitor-induced DNA fragmentation was associated with activation of caspase/ICE family cysteine protease(s) and was blocked by the caspase antagonist, zVADfmk. Analysis of the biochemical mechanisms involved showed that proteasome inhibition resulted in mitochondrial dysregulation leading to the release of cytochrome c and a drop in mitochondrial transmembrane potential (▵Ψ). These changes were associated with inhibition of NFκB, a proteasome-regulated transcription factor that has been implicated in the suppression of apoptosis in other systems. Together, our results suggest that drugs that target the proteasome might be capable of bypassing resistance to conventional chemotherapy in CLL.

Proteasome Inhibitors Decrease AAV2 Capsid-Derived Peptide Epitope Presentation On MHC Class I Following Transduction.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 695-695
Author(s):  
Jonathan D Finn ◽  
Daniel J Hui ◽  
Downey Harre ◽  
Danielle Dunn ◽  
Federico Mingozzi ◽  
...  
Keyword(s):  
T Cell ◽  
Antigen Presentation ◽  
Mhc Class I ◽  
Proteasome Inhibitor ◽  
Proteasome Inhibitors ◽  
Class I ◽  
Large Animal ◽  
Peptide Epitope

Abstract Abstract 695 Adeno-associated viral (AAV) vectors are one of the most extensively studied and highly used vector platforms for gene therapy applications. We have recently provided evidence for AAV capsid-derived antigen presentation through MHC class I on the surface of AAV-transduced cells, supporting the hypothesis that in the first clinical trial using AAV to treat Hemophilia B, AAV capsid proteins were presented on the surface of transduced hepatocytes, resulting in clearance by antigen-specific CD8+ T cells and consequent loss of therapeutic transgene expression. Proteasome inhibitors are small molecule compounds that are able to specifically inhibit the activity of the proteasome, resulting in a buildup of ubiquitinated proteins, increased intracellular reactive oxygen species, and a general decrease in presentation of MHCI-peptide complexes. It has previously been shown that proteasome inhibitors can have a dramatic effect on AAV transduction in vitro and in vivo. Here we describe using the FDA approved proteasome inhibitor, bortezomib, to decrease capsid antigen presentation on hepatocytes in vitro, while at the same time, enhancing gene expression in vivo. Using an AAV capsid specific T cell reporter line to analyze effects of proteasome inhibitor on antigen presentation, we demonstrated capsid antigen presentation at low MOI's, as well as inhibition of antigen presentation at clinically relevant levels of bortezomib. We also demonstrate that bortezomib can enhance FIX expression from an AAV2 vector in C57Bl/6 mice, however does not appear to enhance expression of AAV8. Based on the data presented here, it appears as if future studies using proteasome inhibitors in large animal models may be warranted. A pharmacological agent that can enhance AAV transduction, decrease T-cell activation/proliferation, and decrease antigen presentation would be a promising solution to many of the obstacles to successful translation of AAV-mediated, liver-directed gene transfer to the clinic. Disclosures: No relevant conflicts of interest to declare.

Carfilzomib, An Irreversible Proteasome Inhibitor, Induces Long-Term Growth Inhibition of Mantle Cell Lymphoma In Vivo,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3740-3740
Author(s):  
Liang Zhang ◽  
Jianfei Qian ◽  
Zhishuo Ou ◽  
Luhong Sun ◽  
Kejie Zhang ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Proteasome Inhibitor ◽  
Cell Lymphoma ◽  
Proteasome Inhibitors ◽  
Dependent Manner ◽  
Mantle Cell ◽  
Induced Apoptosis ◽  
Dose Dependent

Abstract Abstract 3740 Mantle cell lymphoma (MCL) is an aggressive B-cell lymphoma with poor clinical outcome, thus, novel therapeutic agents are urgently needed. The proteasome inhibitors are small molecular agents which show significant anti-tumor effect in patients with relapsed/refractory MCL. Carfilzomib, an irreversible proteasome inhibitor with selectivity for the chymotrypsin-like active site, inhibits the proliferation of MCL cells in vitro, as well as the reversible proteasome inhibitor bortezomib. Unlike bortezomib, carfilzomib is good-tolerated and does not induce severe neuropathy in patients. Therefore, carfilzomib can be used in higher dose than bortezomib in vivo. Our study was undertaken to evaluate the therapeutic efficacy of carfilzomib on MCL cells both in vitro and in vivo compared with bortezomib. Four human MCL cell lines, MINO, Jeko-1, MAVER, and NCEB-1, freshly isolated primary MCL cells from the patients with relapsed/refractory MCL, were treated with carfilzomib or bortezomib. A 3H-thymidine incorporation assay showed that both carfilzomib and bortezomib displayed the same dose-dependent manner in inducing growth inhibition of the MCL cells. Similarly, flow cytometry analysis with fluorescence-labeled Annexin V and propidium iodide showed that carfilzomib induced apoptosis of MCL cells in the same dose-dependent manner with bortezomib. However, under the tolerable dose of each of the two proteasome inhibitors, they had different therapeutic effect in a MCL-bearing mouse model established in severe combined immunodeficient (SCID) mice. MINO cells (5 × 106) were inoculated subcutaneously into the right flank of SCID mice. Three weeks later, after palpable tumors developed, mice were treated intravenously with carfilzomib (5 mg/kg) on day 1 and day2, for 5 cycles, or treated intraperitoneally with bortezomib (1 mg/kg) on days 1, 4, 7 and 10, per 21 days. Tumor growth was almost abrogated after treatment with carfilzomib compared with bortezomib, and the survival time of tumor-bearing mice was significantly prolonged in the carfilzomib-treated mice versus bortezomib-treated mice. Notably, Increasing the frequency or dose of bortezomib treatment was unable because the mice were too suffered in toxicity to tolerate the treatment. Western blot analysis showed that carfilzomib induced apoptosis in caspase-dependent manner as well as bortezomib. Carfilzomib inhibited the phosphorylation of IκB, STAT3, and AKT and irreversibly blocked the release of NFκB to nuclei. In conclusion, carfilzomib displays the same anti-tumor effect and mechanism with bortezomib on MCL cells in vitro. However, carfilzomib but not bortezomib is well tolerated without severe side effect in vivo. Carfilzomib significantly inhibits tumor growth and prolongs survival indicating that carfilzomib is a potential agent in MCL chemotherapy. Disclosures: No relevant conflicts of interest to declare.

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