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.

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.

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.

Pre-Clinical Activity of the Novel, First-in-Class p97 Inhibitor, CB-5083, in Multiple Myeloma

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4701-4701
Author(s):  
Blake T. Aftab ◽  
Daniel J Anderson ◽  
Ronan Le Moigne ◽  
Stevan Djakovic ◽  
Eugen Dhimolea ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Cell Lines ◽  
Proteasome Inhibitor ◽  
Stromal Cell ◽  
Hematological Malignancies ◽  
Proteasome Inhibitors ◽  
Protein Homeostasis ◽  
Ubiquitinated Proteins

Abstract Hematological malignancies such as multiple myeloma (MM) have an increased reliance on the ubiquitin proteasome system (UPS) presumably as a consequence of their high protein synthetic and secretory burden. Chemical agents that target the proteasome, such as bortezomib and carfilzomib, have been successful in treating multiple myeloma; however patients treated with these drugs ultimately relapse. The AAA-ATPase p97/VCP (p97) facilitates ATP-dependent extraction and degradation of ubiquitinated proteins destined for proteasomal elimination. In addition to ubiquitin-dependent protein degradation, p97 is also closely involved in other aspects of protein homeostasis, including endoplasmic reticulum-associated degradation (ERAD) and autophagy. Pharmacologic inhibition of p97 provides a compelling therapeutic approach for hematological malignancies that rely on tight regulation of protein homeostasis as a component of their survival. CB-5083 is a novel small molecule inhibitor of p97 ATPase activity with nanomolar enzymatic and cellular potency. Treatment of cancer cells with CB-5083 causes a dramatic increase in poly-ubiquitinated proteins as well as an accumulation of substrates of the UPS and ERAD. CB-5083 causes a profound induction of the unfolded protein response (UPR) with consequent activation of the DR5 death receptor, caspase 8, caspase 3/7 and ultimately cell death. Induction of the UPR occurs to a greater magnitude with CB-5083 when compared to the proteasome inhibitor, bortezomib, suggesting the potential for increased efficacy in cancers with sensitivity to UPR-mediated cell death. In addition, activation of apoptosis and cell death occur more rapidly with CB-5083 than with bortezomib. Sequencing of cell lines made resistant to CB-5083 reveals missense mutations mapping to the D2 ATPase site in p97, supporting on-target association with cytotoxicity. In an expanded panel of MM cell lines there is no correlation between the cytotoxic sensitivity to CB-5083 and the cytotoxic sensitivity to proteasome inhibitors, suggesting differential mechanisms of cytotoxicity and potential activity of CB-5083 in proteasome inhibitor resistant settings. Compared to myeloma cell lines, CB-5083 has reduced cytotoxic potency in immortalized stromal cell lines and in patient-derived CD138-negative bone marrow mononuclear cells. Furthermore, unlike the reduced potency demonstrated by carfilzomib in the context of MM cell-bone marrow stromal cell (BMSC) interactions, the cyto-reductive potential of CB-5083 is unaffected in co-cultures of MM cells with patient-derived BMSCs or immortalized BMSCs from healthy donors. In vivo, CB-5083 is orally bioavailable, shows a pharmacodynamic effect in tumor tissue (as measured by poly-ubiquitin accumulation) and demonstrates robust anti-tumor activity across several MM models. CB-5083 treatment of mice bearing subcutaneous xenografts leads to tumor stasis and regression in RPMI8226 and AMO1 MM models, respectively. In advanced models of disseminated, ortho-metastatic disease, intermittent oral administration of CB-5083 demonstrates significant inhibition of myeloma burden and improves survival, with an overall efficacy profile that compares favorably to that of clinically approved proteasome inhibitors. Furthermore, in the Vk*Myc genetically engineered mouse model of MM, treatment with CB-5083 results in a significant reduction in M-spike by 55%. Combination treatment of mice bearing the RPMI8226 subcutaneous xenograft model with CB-5083, dexamethasone and lenalidomide results in tumor regression. Taken together, these data demonstrate that CB-5083 is a potent and selective inhibitor of the p97 ATPase with robust activity in vitro and in vivo in numerous MM models and strongly support clinical evaluation. Based on these observations, a phase 1 dose-escalation trial has recently been initiated and is currently underway in patients with relapsed/refractory multiple myeloma. Disclosures Anderson: Cleave Biosciences: Employment. Le Moigne:Cleave Biosciences: Employment. Djakovic:Cleave Biosciences: Employment. Rice:Cleave Biosciences: Employment. Wong:Cleave Biosciences: Employment. Kumar:Cleave Biosciences: Employment. Valle:Cleave Biosciences: Employment. Menon:Cleave Biosciences: Employment. Kiss von Soly:Cleave Biosciences: Employment. Wang:Cleave Biosciences: Employment. Yao:Cleave Biosciences: Employment. Soriano:Cleave Biosciences: Employment. Bergsagel:ONYX: Consultancy; Janssen: Consultancy; BMS: Consultancy; Novartis: Research Funding. Yakes:Cleave Biosciences: Employment. Zhou:Cleave Biosciences: Employment. Wustrow:Cleave Biosciences: Employment. Rolfe:Cleave Biosciences: Employment.

Clinical Trial of NPI-0052 (2nd generation proteasome inhibitor) in Patients Having Advanced Malignancies with Expanded RP2D Cohorts in Lymphoma and CLL

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4934-4934 ◽  
Author(s):  
Timothy Price ◽  
Peeter Padrik ◽  
Amanda Townsend ◽  
Paul Mainwaring ◽  
Lawrence Catley ◽  
...  
Keyword(s):  
Solid Tumors ◽  
Solid Tumor ◽  
Proteasome Inhibitor ◽  
Standard Of Care ◽  
Proteasome Inhibition ◽  
Hematologic Malignancies ◽  
Preclinical Research ◽  
Novel Structure ◽  
Advanced Malignancies ◽  
Mantle Cell

Abstract Background: NPI-0052 is a novel proteasome inhibitor that produces prolonged inhibition of the 20S proteasome. NPI-0052 has a novel structure leading to a unique proteasome inhibition, toxicology and effect profile. Preclinical research suggests an improved therapeutic ratio and activity in hematologic and solid tumor malignancy models. Secondary to these findings, clinical trials are being conducted in patients with myeloma, lymphomas, leukemias and solid tumors. Materials and Methods: In this study patients with solid tumor, lymphoma or leukemia diagnoses were treated with NPI-0052 administered weekly, for 3 weeks in 4-week cycles in a 3+3 design dose escalation. The dose of NPI-0052 was escalated in 50–100% increments dependent on observed adverse events (AE). In addition to regular safety monitoring, proteasome inhibition (PI) (baseline, D1 & D15) and pharmacokinetics PK (D1 & D15) were assayed in blood. Once a Recommended Phase 2 Dose (RP2D) is identified, RP2D cohorts of 10 patients in each lymphoma and CLL are enrolled. Results: 25 patients have been treated at doses ranging from 0.1 mg/m2 to 0.7 mg/m2. The AE profile has been very tolerable with fatigue, transient peri-infusion site discomfort and lymphopenia being commonly ascribed to NPI-0052. Whole blood pharmacokinetics were calculated for all patients on study. At the highest dose assessed PK parameters were (mean ± SD) AUCtot =215±129 ng/mL*min; Cmax =22.8 ±14 ng/mL; t1/2 =13.5 ± 9.2 mins; clearance= 7.8 ± 8.2 L/min and Vss = 132 ± 192 L. AUC and Cmax increased linearly with dose and the kinetics are apparently not dose dependant. PI has been assayed in blood, indicating a dose:response relationship with inhibition of chymotrypsin-like activity up to 100% observed and mean Day 1 inhibition of 78%. This level of proteasome inhibition is higher than that reported with standard doses of bortezomib, yet the profile of adverse drug reactions associated with bortezomib has not been observed. A total of 7 patients (33%) have had stable disease for at least 2 cycles (8 weeks; 2months), including one each with mantle cell lymphoma (4 cycles), Hodgkin’s lymphoma (4 cycles), follicular lymphoma (4 cycles) and sarcoma (5 cycles) and prostate adenocarcinoma, and two with melanoma (4 cycles). Conclusions: NPI-0052 produces dose-dependent pharmacologic effects through the predicted efficacious range while producing a toxicity profile that is tolerable and dissimilar to that of the standard of care proteasome inhibitor bortezomib. These data have supported additional studies being initiated in hematologic malignancies and solid tumors.

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.

Reduction of Skeletal Muscle Atrophy by a Proteasome Inhibitor in a Rat Model of Denervation

2006 ◽  
Vol 231 (3) ◽  
pp. 335-341 ◽  
Author(s):  
Blake C. Beehler ◽  
Paul G. Sleph ◽  
Latifa Benmassaoud ◽  
Gary J. Grover
Keyword(s):  
Skeletal Muscle ◽  
Muscle Mass ◽  
Muscle Atrophy ◽  
Proteasome Inhibitor ◽  
Proteasome Inhibitors ◽  
Levator Ani ◽  
Proteasome Inhibition ◽  
Skeletal Muscle Atrophy ◽  
Mrna Levels

The ubiquitin-proteasome system is the primary proteolytic pathway implicated in skeletal muscle atrophy under catabolic conditions. Although several studies showed that proteasome inhibitors reduced proteolysis under catabolic conditions, few studies have demonstrated the ability of these inhibitors to preserve skeletal muscle mass and architecture in vivo. To explore this, we studied the effect of the proteasome inhibitor Velcade (also known as PS-341 and bortezomib) in denervated skeletal muscle in rats. Rats were given vehicle or Velcade (3 mg/kg po) daily for 7 days beginning immediately after induction of muscle atrophy by crushing the sciatic nerve. At the end of the study, the rats were euthanized and the soleus and extensor digitorum longus (EDL) muscles were harvested. In vehicle-treated rats, denervation caused a 33.5 ± 2.8% and 16.2 ± 2.7% decrease in the soleus and EDL muscle wet weights (% atrophy), respectively, compared to muscles from the contralateral (innervated) limb. Velcade significantly reduced denervation-induced atrophy to 17.1 ± 3.3% in the soleus (P < 0.01), a 51.6% reduction in atrophy associated with denervation, with little effect on the EDL (9.8 ± 3.2% atrophy). Histology showed a Preservation of muscle mass and preservation of normal cellular architecture after Velcade treatment. Ubiquitin mRNA levels in denervated soleus muscle at the end of the study were significantly elevated 120 ± 25% above sham control levels and were reduced to control levels by Velcade. In contrast, testosterone proprionate (3 mg/kg sc) did not alleviate denervation-induced skeletal muscle atrophy but did prevent castration-induced levator ani atrophy, while Velcade was without effect. These results show that proteasome inhibition attenuates denervation-induced muscle atrophy in vivo in soleus muscles. However, this mechanism may not be operative in all types of atrophy.

scholarly journals In Vivo Pharmacodynamic Imaging of Proteasome Inhibition

2009 ◽  
Vol 8 (3) ◽  
pp. 7290.2009.00007 ◽  
Author(s):  
Erin A. Kimbrel ◽  
Tina N. Davis ◽  
James E. Bradner ◽  
Andrew L. Kung
Keyword(s):  
Dynamic Range ◽  
Hypoxia Inducible Factor ◽  
Proteasome Inhibitors ◽  
Surrogate Marker ◽  
Proteasome Inhibition ◽  
26S Proteasome ◽  
Medical Need ◽  
Apoptotic Effects

Inhibiting the proteolytic activity of the 26S proteasome has been shown to have selective apoptotic effects on cancer cells and to be clinically efficacious in certain malignancies. There is an unmet medical need for additional proteasome inhibitors, and their development will be facilitated by surrogate markers of proteasome function. Toward this end, ectopic fusion of the destruction domain from ornithine decarboxylase (ODC) to reporter proteins is often used for assessing proteasome function. For luciferase-based reporters, we hypothesized that the oxygen-dependent destruction domain (ODD) from hypoxia-inducible factor 1α (HIF-1α) may provide improved sensitivity over luciferase-ODC, owing to its extremely rapid turnover by the proteasome (HIF-1α has a half-life of less than 5 minutes). In the current study, we show that ODD-luciferase affords a greater dynamic range and faster kinetics than luciferase-ODC in sensing proteasome inhibition in vitro. Importantly, ODD-luciferase also serves as an effective in vivo marker of proteasome function in xenograft tumor models, with inhibition being detected by noninvasive imaging within 3 hours of bortezomib administration. These data establish ODD-luciferase as a surrogate marker of proteasome function that can be used both in vitro and in vivo for the development of novel proteasome inhibitors.

scholarly journals Targeting PELP1 Attenuates Angiogenesis and Enhances Chemotherapy Efficiency in Colorectal Cancer

Cancers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 383
Author(s):  
Jianlin Zhu ◽  
Lu Wang ◽  
Fan Liu ◽  
Jinghua Pan ◽  
Zhimeng Yao ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Solid Tumors ◽  
Therapeutic Strategy ◽  
Umbilical Vein ◽  
Defined Contribution ◽  
Cancer Types ◽  
Control Tumor ◽  
Umbilical Vein Endothelial Cells ◽  
Oncogenic Protein

Abnormal angiogenesis is one of the important hallmarks of colorectal cancer as well as other solid tumors. Optimally, anti-angiogenesis therapy could restrain malignant angiogenesis to control tumor expansion. PELP1 is as a scaffolding oncogenic protein in a variety of cancer types, but its involvement in angiogenesis is unknown. In this study, PELP1 was found to be abnormally upregulated and highly coincidental with increased MVD in CRC. Further, treatment with conditioned medium (CM) from PELP1 knockdown CRC cells remarkably arrested the function of human umbilical vein endothelial cells (HUVECs) compared to those treated with CM from wildtype cells. Mechanistically, the STAT3/VEGFA axis was found to mediate PELP1-induced angiogenetic phenotypes of HUVECs. Moreover, suppression of PELP1 reduced tumor growth and angiogenesis in vivo accompanied by inactivation of STAT3/VEGFA pathway. Notably, in vivo, PELP1 suppression could enhance the efficacy of chemotherapy, which is caused by the normalization of vessels. Collectively, our findings provide a preclinical proof of concept that targeting PELP1 to decrease STAT3/VEGFA-mediated angiogenesis and improve responses to chemotherapy due to normalization of vessels. Given the newly defined contribution to angiogenesis of PELP1, targeting PELP1 may be a potentially ideal therapeutic strategy for CRC as well as other solid tumors.

scholarly journals Targeting ubiquitin-activating enzyme induces ER stress–mediated apoptosis in B-cell lymphoma cells

2019 ◽  
Vol 3 (1) ◽  
pp. 51-62 ◽  
Author(s):  
Scott Best ◽  
Taylor Hashiguchi ◽  
Adam Kittai ◽  
Nur Bruss ◽  
Cody Paiva ◽  
...  
Keyword(s):  
Er Stress ◽  
B Cell ◽  
Cell Lines ◽  
Cell Lymphoma ◽  
Proteasome Inhibitors ◽  
B Cell Lymphoma ◽  
Proteasome Inhibition ◽  
Cell Of Origin ◽  
Protein Ubiquitination

Abstract Alterations in the ubiquitin proteasome system (UPS) leave malignant cells in heightened cellular stress, making them susceptible to proteasome inhibition. However, given the limited efficacy of proteasome inhibitors in non-Hodgkin lymphoma (NHL), novel approaches to target the UPS are needed. Here, we show that TAK-243, the first small-molecule inhibitor of the ubiquitin activating enzyme (UAE) to enter clinical development, disrupts all ubiquitin signaling and global protein ubiquitination in diffuse large B-cell lymphoma (DLBCL) cells, thereby inducing endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). Activation of the ER stress response protein kinase R (PKR)–like ER kinase and phosphorylation of eukaryotic translation initiator factor 2α led to upregulation of the proapoptotic molecule C/EBP homologous protein and cell death across a panel of DLBCL cell lines independent of cell of origin. Concurrently, targeting UAE led to accumulation of Cdt1, a replication licensing factor, leading to DNA rereplication, checkpoint activation, and cell cycle arrest. MYC oncoprotein sensitized DLBCL cells to UAE inhibition; engineered expression of MYC enhanced while genetic MYC knockdown protected from TAK-243–induced apoptosis. UAE inhibition demonstrated enhanced ER stress and UPR and increased potency compared with bortezomib in DLBCL cell lines. In vivo treatment with TAK-243 restricted the growth of xenografted DLBCL tumors, accompanied by reduced cell proliferation and apoptosis. Finally, primary patient-derived DLBCL cells, including those expressing aberrant MYC, demonstrated susceptibility to UAE inhibition. In sum, targeting UAE may hold promise as a novel therapeutic approach in NHL.

scholarly journals Isoginkgetin, a Natural Biflavonoid Proteasome Inhibitor, Sensitizes Cancer Cells to Apoptosis via Disruption of Lysosomal Homeostasis and Impaired Protein Clearance

2019 ◽  
Vol 39 (10) ◽  
Author(s):  
Jessica Tsalikis ◽  
Mena Abdel-Nour ◽  
Armin Farahvash ◽  
Matthew T. Sorbara ◽  
Stephanie Poon ◽  
...  
Keyword(s):  
Cell Death ◽  
Proteasome Inhibitor ◽  
Adaptor Protein ◽  
Proteasome Inhibition ◽  
20S Proteasome ◽  
Protein Homeostasis ◽  
Cancer Cell Death ◽  
Protein Clearance ◽  
Lysosome Biogenesis

ABSTRACTProtein degradation pathways are critical for maintaining proper protein dynamics within the cell, and considerable efforts have been made toward the development of therapeutics targeting these catabolic processes. We report here that isoginkgetin, a naturally derived biflavonoid, sensitized cells undergoing nutrient starvation to apoptosis, induced lysosomal stress, and activated the lysosome biogenesis geneTFEB. Isoginkgetin treatment led to the accumulation of aggregates of polyubiquitinated proteins that colocalized strongly with the adaptor protein p62, the 20S proteasome, and the endoplasmic reticulum-associated degradation (ERAD) protein UFD1L. Isoginkgetin directly inhibited the chymotrypsin-like, trypsin-like, and caspase-like activities of the 20S proteasome and impaired NF-κB signaling, suggesting that the molecule may display its biological activity in part through proteasome inhibition. Importantly, isoginkgetin was effective at killing multiple myeloma (MM) cell linesin vitroand displayed a higher rate of cell death induction than the clinically approved proteasome inhibitor bortezomib. We propose that isoginkgetin disturbs protein homeostasis, leading to an excess of protein cargo that places a burden on the lysosomes/autophagic machinery, eventually leading to cancer cell death.

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