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.

Potentiation of Bortezomib-Induced Killing of Lymphoma Cells by Inhibition of Autophagy and Prevention of I-κBα Degradation

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 116-116
Author(s):  
Li Jia ◽  
Ganga Gopinathan ◽  
Johanna T Sukumar ◽  
John G. Gribben
Keyword(s):  
Cell Death ◽  
B Cell ◽  
Proteasome Inhibitor ◽  
Proteasome Inhibitors ◽  
Adaptor Protein ◽  
Proteasome Inhibition ◽  
Differential Sensitivity ◽  
Lymphoma Cells ◽  
Ubiquitinated Proteins ◽  
Apoptotic Proteins

Abstract Abstract 116 Previous studies have shown that germinal center B cell-like (GCB) diffuse large B-cell lymphoma (DLBCL) are resistant to proteasome inhibitors such as bortezomib. The mechanism by which GCB-DLBCL cells escape from proteasome inhibitor-induced apoptosis is unclear. To investigate this further, we examined the proteasomal pathway, expression of anti-apoptotic proteins and autophagy. Using bortezomib or MG-262, we show that DLBCL cells have differential sensitivity to proteasome inhibitor-mediated cell death, even though the effects on proteasome inhibition were similar. DLBCL cells that either over-express anti-apoptotic proteins such as Bcl-2, or lack pro-apoptotic proteins including Bax/Bak, are more resistant to proteasome inhibitor-induced reduction of mitochondrial membrane potential and activation of caspase-3. Treatment with bortezomib induced autophagy in both sensitive and resistant DLBCL cells, as demonstrated by an accumulation and aggregation of the autophagy marker protein LC3-II. Bortezomib induced accumulation of ubiquitinated proteins and a decrease in the adaptor protein p62, indicating activation of autophagic degradation. Fluorescent microscopy revealed that bortezomib induced p62 recruits both ubiquitinated proteins and LC3-II, suggesting that p62 leads ubiquitinated protein to autophagosomes. Treatment with bortezomib thereby promotes I-kBα degradation, demonstrating that the route of I-κBα degradation is not via the ubiquitin-proteasome degradation system. Bortezomib-induced I-kBα degradation was detected in both DLBCL cell lines and primary DLBCL and follicular lymphoma samples. Chloroquine (CQ), an inhibitor of autophagy, significantly increased bortezomib-induced accumulation of p62 and ubiquitinated proteins, including I-κBα, Bax and p53. CQ alone induced a dose-dependent increase in I-kBα protein levels, indicating that I-κBα protein can be degraded by autophagy even in the absence of proteasome inhibition. Importantly, the combination of proteasome and autophagy inhibitors shows great potential to kill apoptosis-resistant lymphoma cells. Proteasome inhibitor with or without CQ induced cell death in DLBCL cells cannot be blocked completely by either caspase inhibitors or knockdown of Bax/Bak proteins, suggesting that cell death occurs via a caspase-independent pathway. In summary, proteasome inhibitors induce autophagy and confer DLBCL cells resistance by eliminating I-κBα and possibly other pro-apoptotic proteins. Addition of autophagy inhibitors to bortezomib has the potential to induce increased killing in patients with resistant lymphoma. Disclosures: Gribben: Roche: Consultancy; Celgene: Consultancy; GSK: Honoraria; Napp: Honoraria.

Stew in its Own Juice: Protein Homeostasis Machinery Inhibition Reduces Cell Viability in Multiple Myeloma Cell Lines

2019 ◽  
Vol 19 (2) ◽  
pp. 112-119 ◽  
Author(s):  
Mariana B. de Oliveira ◽  
Luiz F.G. Sanson ◽  
Angela I.P. Eugenio ◽  
Rebecca S.S. Barbosa-Dantas ◽  
Gisele W.B. Colleoni
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Cell Viability ◽  
Cell Lines ◽  
Treatment Options ◽  
Compensatory Mechanism ◽  
Protein Homeostasis ◽  
Protein Response ◽  
Rpmi 8226

Introduction:Multiple myeloma (MM) cells accumulate in the bone marrow and produce enormous quantities of immunoglobulins, causing endoplasmatic reticulum stress and activation of protein handling machinery, such as heat shock protein response, autophagy and unfolded protein response (UPR).Methods:We evaluated cell lines viability after treatment with bortezomib (B) in combination with HSP70 (VER-15508) and autophagy (SBI-0206965) or UPR (STF- 083010) inhibitors.Results:For RPMI-8226, after 72 hours of treatment with B+VER+STF or B+VER+SBI, we observed 15% of viable cells, but treatment with B alone was better (90% of cell death). For U266, treatment with B+VER+STF or with B+VER+SBI for 72 hours resulted in 20% of cell viability and both treatments were better than treatment with B alone (40% of cell death). After both triplet combinations, RPMI-8226 and U266 presented the overexpression of XBP-1 UPR protein, suggesting that it is acting as a compensatory mechanism, in an attempt of the cell to handle the otherwise lethal large amount of immunoglobulin overload.Conclusion:Our in vitro results provide additional evidence that combinations of protein homeostasis inhibitors might be explored as treatment options for MM.

Phase I Trial of the Proteasome Inhibitor PS-341 in Patients With Refractory Hematologic Malignancies

2002 ◽  
Vol 20 (22) ◽  
pp. 4420-4427 ◽  
Author(s):  
Robert Z. Orlowski ◽  
Thomas E. Stinchcombe ◽  
Beverly S. Mitchell ◽  
Thomas C. Shea ◽  
Albert S. Baldwin ◽  
...  
Keyword(s):  
Proteasome Inhibitor ◽  
Proteasome Inhibition ◽  
Complete Response ◽  
Hematologic Malignancies ◽  
Maximum Tolerated Dose ◽  
20S Proteasome ◽  
Dependent Manner ◽  
Mantle Cell ◽  
Heavily Pretreated ◽  
Systemic Hypersensitivity

PURPOSE: To determine the maximum-tolerated dose (MTD), dose-limiting toxicity (DLT), and pharmacodynamics (PD) of the proteasome inhibitor bortezomib (previously known as PS-341) in patients with refractory hematologic malignancies.PATIENTS AND METHODS: Patients received PS-341 twice weekly for 4 weeks at either 0.40, 1.04, 1.20, or 1.38 mg/m2, followed by a 2-week rest. The PD of PS-341 was evaluated by measurement of whole blood 20S proteasome activity.RESULTS: Twenty-seven patients received 293 doses of PS-341, including 24 complete cycles. DLTs at doses above the 1.04-mg/m2MTD attributed to PS-341 included thrombocytopenia, hyponatremia, hypokalemia, fatigue, and malaise. In three of 10 patients receiving additional therapy, serious reversible adverse events appeared during cycle 2, including one episode of postural hypotension, one systemic hypersensitivity reaction, and grade 4 transaminitis in a patient with hepatitis C and a substantial acetaminophen ingestion. PD studies revealed PS-341 induced 20S proteasome inhibition in a time-dependent manner, and this inhibition was also related to both the dose in milligrams per meter squared, and the absolute dose of PS-341. Among nine fully assessable patients with heavily pretreated plasma cell dyscrasias completing one cycle of therapy, there was one complete response and a reduction in paraprotein levels and/or marrow plasmacytosis in eight others. In addition, one patient with mantle cell lymphoma and another with follicular lymphoma had shrinkage of nodal disease.CONCLUSION: PS-341 was well tolerated at 1.04 mg/m2on this dose-intensive schedule, although patients need to be monitored for electrolyte abnormalities and late toxicities. Additional studies are indicated to determine whether incorporation of dose/body surface area yields a superior PD model to dosing without normalization. PS-341 showed activity against refractory multiple myeloma and possibly non-Hodgkin’s lymphoma in this study, and merits further investigation in these populations.

scholarly journals Hydrogen Phosphate Selectively Induces MDA-MB-231 Breast Cancer Cell Death in vitro

2021 ◽  
Author(s):  
Aya Shanti ◽  
Kenana Al Adem ◽  
Cesare Stefanini ◽  
Sungmun Lee
Keyword(s):  
Breast Cancer ◽  
Cell Death ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Dihydrogen Phosphate ◽  
Human Breast ◽  
Hydrogen Phosphate ◽  
Cancer Cell Death ◽  
Phosphate Ions

Abstract Phosphate ions are the most abundant anions inside the cells, and they are increasingly gaining attention as key modulators of cellular function and gene expression. However, little is known about the effect of inorganic phosphate ions on cancer cells, particularly breast cancer cells. Here, we investigated the toxicity of different phosphate compounds to triple-negative human breast cancer cells (MDA-MB-231) and compared it to that of human monocytes (THP-1). We found that, unlike dihydrogen phosphate (H2PO4−), hydrogen phosphate (HPO42−) at 20 mM or lower concentrations induced breast cancer (MDA-MB-231) cell death more than immune (THP-1) cell death. We correlate this effect to the fact that phosphate in the form of HPO42− raises pH levels to alkaline levels which are not optimum for transport of phosphate into cancer cells. The results in this study highlight the importance of further exploring hydrogen phosphate (HPO42−) as a potential therapeutic for the treatment of breast cancer.

scholarly journals Immunomodulatory activity of IR700-labelled affibody targeting HER2

2020 ◽  
Vol 11 (10) ◽  
Author(s):  
Justyna Mączyńska ◽  
Chiara Da Pieve ◽  
Thomas A. Burley ◽  
Florian Raes ◽  
Anant Shah ◽  
...  
Keyword(s):  
Cell Death ◽  
Cancer Cells ◽  
Light Irradiation ◽  
Immunomodulatory Activity ◽  
Her2 Positive ◽  
Immunological Responses ◽  
Cancer Cell Death ◽  
Immature Dendritic Cells

Abstract There is an urgent need to develop therapeutic approaches that can increase the response rate to immuno-oncology agents. Photoimmunotherapy has recently been shown to generate anti-tumour immunological responses by releasing tumour-associated antigens from ablated tumour cell residues, thereby enhancing antigenicity and adjuvanticity. Here, we investigate the feasibility of a novel HER2-targeted affibody-based conjugate (ZHER2:2395-IR700) selectively to induce cancer cell death in vitro and in vivo. The studies in vitro confirmed the specificity of ZHER2:2395-IR700 binding to HER2-positive cells and its ability to produce reactive oxygen species upon light irradiation. A conjugate concentration- and light irradiation-dependent decrease in cell viability was also demonstrated. Furthermore, light-activated ZHER2:2395-IR700 triggered all hallmarks of immunogenic cell death, as defined by the translocation of calreticulin to the cell surface, and the secretion of ATP, HSP70/90 and HMGB1 from dying cancer cells into the medium. Irradiating a co-culture of immature dendritic cells (DCs) and cancer cells exposed to light-activated ZHER2:2395-IR700 enhanced DC maturation, as indicated by augmented expression of CD86 and HLA-DR. In SKOV-3 xenografts, the ZHER2:2395-IR700-based phototherapy delayed tumour growth and increased median overall survival. Collectively, our results strongly suggest that ZHER2:2395-IR700 is a promising new therapeutic conjugate that has great potential to be applicable for photoimmunotherapy-based regimens.

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 Mitochondrial Cell Death Suppressors Carried by Human and Murine Cytomegalovirus Confer Resistance to Proteasome Inhibitor-Induced Apoptosis

2005 ◽  
Vol 79 (19) ◽  
pp. 12205-12217 ◽  
Author(s):  
A. Louise McCormick ◽  
Christopher D. Meiering ◽  
Geoffrey B. Smith ◽  
Edward S. Mocarski
Keyword(s):  
Cell Death ◽  
Viral Genome ◽  
Proteasome Inhibitor ◽  
Proteasome Inhibition ◽  
Murine Cytomegalovirus ◽  
Viral Inhibitor ◽  
Infected Cells ◽  
Induced Apoptosis ◽  
Functional Copy ◽  
Inactivating Mutations

ABSTRACT Human cytomegalovirus carries a mitochondria-localized inhibitor of apoptosis (vMIA) that is conserved in primate cytomegaloviruses. We find that inactivating mutations within UL37x1, which encodes vMIA, do not substantially affect replication in TownevarATCC (Towne-BAC), a virus that carries a functional copy of the betaherpesvirus-conserved viral inhibitor of caspase 8 activation, the UL36 gene product. In Towne-BAC infection, vMIA reduces susceptibility of infected cells to intrinsic death induced by proteasome inhibition. vMIA is sufficient to confer resistance to proteasome inhibition when expressed independent of viral infection. Murine cytomegalovirus m38.5, whose position in the viral genome is analogous to UL37x1, exhibits mitochondrial association and functions in much the same manner as vMIA in inhibiting intrinsic cell death. This work suggests a common role for vMIA in rodent and primate cytomegaloviruses, modulating the threshold of virus-infected cells to intrinsic cell death.

Degradation of mutant huntingtin via the ubiquitin/proteasome system is modulated by FE65

2012 ◽  
Vol 443 (3) ◽  
pp. 681-689 ◽  
Author(s):  
Wan Ning Vanessa Chow ◽  
Hon Wing Luk ◽  
Ho Yin Edwin Chan ◽  
Kwok-Fai Lau
Keyword(s):  
Cell Death ◽  
Degradation Mechanism ◽  
Neuronal Cell Death ◽  
Neuronal Cell ◽  
Adaptor Protein ◽  
Ubiquitin Proteasome System ◽  
Exon 1 ◽  
Ubiquitin Proteasome

An unstable expansion of the polyglutamine repeat within exon 1 of the protein Htt (huntingtin) causes HD (Huntington's disease). Mounting evidence shows that accumulation of N-terminal mutant Htt fragments is the source of disruption of normal cellular processes which ultimately leads to neuronal cell death. Understanding the degradation mechanism of mutant Htt and improving its clearance has emerged as a new direction in developing therapeutic approaches to treat HD. In the present study we show that the brain-enriched adaptor protein FE65 is a novel interacting partner of Htt. The binding is mediated through WW–polyproline interaction and is dependent on the length of the polyglutamine tract. Interestingly, a reduction in mutant Htt protein level was observed in FE65-knockdown cells, and the process requires the UPS (ubiquitin/proteasome system). Moreover, the ubiquitination level of mutant Htt was found to be enhanced when FE65 is knocked down. Immunofluroescence staining revealed that FE65 associates with mutant Htt aggregates. Additionally, we demonstrated that overexpression of FE65 increases mutant Htt-induced cell death both in vitro and in vivo. These results suggest that FE65 facilitates the accumulation of mutant Htt in cells by preventing its degradation via the UPS, and thereby enhances the toxicity of mutant Htt.

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