proteasome inhibitor
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Author(s):  
Masahiko Takahashi ◽  
Hiroki Kitaura ◽  
Akiyoshi Kakita ◽  
Taichi Kakihana ◽  
Yoshinori Katsuragi ◽  
...  

TDP-43 is a causative factor of amyotrophic lateral sclerosis (ALS). Cytoplasmic TDP-43 aggregates in neurons are a hallmark pathology of ALS. Under various stress conditions, TDP-43 localizes sequentially to two cytoplasmic protein aggregates: stress granules (SGs) first, and then aggresomes. Accumulating evidence suggests that delayed clearance of TDP-43-positive SGs is associated with pathological TDP-43 aggregates in ALS. We found that USP10 promotes the clearance of TDP-43-positive SGs in cells treated with proteasome inhibitor, thereby promoting the formation of TDP-43-positive aggresomes, and the depletion of USP10 increases the amount of insoluble TDP-35, a cleaved product of TDP-43, in the cytoplasm. TDP-35 interacted with USP10 in an RNA-binding dependent manner; however, impaired RNA-binding of TDP-35 reduced the localization in SGs and aggresomes and induced USP10-negative TDP-35 aggregates. Immunohistochemistry showed that most of the cytoplasmic TDP-43/TDP-35-aggregates in the neurons of ALS patients were USP10-negative. Our findings suggest that USP10 inhibits aberrant aggregation of TDP-43/TDP-35 in the cytoplasm of neuronal cells by promoting the clearance of TDP-43/TDP-35-positive SGs and facilitating the formation of TDP-43/TDP-35-positive aggresomes.


Author(s):  
Chunyan Gu ◽  
Yajun Wang ◽  
Lulin Zhang ◽  
Li Qiao ◽  
Shanliang Sun ◽  
...  

Abstract Background Currently, multiple myeloma (MM) is still an incurable plasma cell malignancy in urgent need of novel therapeutic targets and drugs. Methods Bufalin was known as a highly toxic but effective anti-cancer compound. We used Bufalin as a probe to screen its potential targets by proteome microarray, in which AHSA1 was the unique target of Bufalin. The effects of AHSA1 on cellular proliferation and drug resistance were determined by MTT, western blot, flow cytometry, immunohistochemistry staining and xenograft model in vivo. The potential mechanisms of Bufalin and KU-177 in AHSA1/HSP90 were verified by co-immunoprecipitation, mass spectrometry, site mutation and microscale thermophoresis assay. Results AHSA1 expression was increased in MM samples compared to normal controls, which was significantly associated with MM relapse and poor outcomes. Furthermore, AHSA1 promoted MM cell proliferation and proteasome inhibitor (PI) resistance in vitro and in vivo. Mechanism exploration indicated that AHSA1 acted as a co-chaperone of HSP90A to activate CDK6 and PSMD2, which were key regulators of MM proliferation and PI resistance respectively. Additionally, we identified AHSA1-K137 as the specific binding site of Bufalin on AHSA1, mutation of which decreased the interaction of AHSA1 with HSP90A and suppressed the function of AHSA1 on mediating CDK6 and PSMD2. Intriguingly, we discovered KU-177, an AHSA1 selective inhibitor, and found KU-177 targeting the same site as Bufalin. Bufalin and KU-177 treatments hampered the proliferation of flow MRD-positive cells in both primary MM and recurrent MM patient samples. Moreover, KU-177 abrogated the cellular proliferation and PI resistance induced by elevated AHSA1, and decreased the expression of CDK6 and PSMD2. Conclusions We demonstrate that AHSA1 may serve as a promising therapeutic target for cellular proliferation and proteasome inhibitor resistance in multiple myeloma.


Neoplasia ◽  
2022 ◽  
Vol 24 (1) ◽  
pp. 1-11
Author(s):  
Melissa K. Bennett ◽  
Manjun Li ◽  
Melinda N. Tea ◽  
Melissa R. Pitman ◽  
John Toubia ◽  
...  

Biomolecules ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 51
Author(s):  
Jianhao Liu ◽  
Ruogang Zhao ◽  
Xiaowen Jiang ◽  
Zhaohuan Li ◽  
Bo Zhang

Bortezomib (BTZ) is the first proteasome inhibitor approved by the Food and Drug Administration. It can bind to the amino acid residues of the 26S proteasome, thereby causing the death of tumor cells. BTZ plays an irreplaceable role in the treatment of mantle cell lymphoma and multiple myeloma. Moreover, its use in the treatment of other hematological cancers and solid tumors has been investigated in numerous clinical trials and preclinical studies. Nevertheless, the applications of BTZ are limited due to its insufficient specificity, poor permeability, and low bioavailability. Therefore, in recent years, different BTZ-based drug delivery systems have been evaluated. In this review, we firstly discussed the functions of proteasome inhibitors and their mechanisms of action. Secondly, the properties of BTZ, as well as recent advances in both clinical and preclinical research, were reviewed. Finally, progress in research regarding BTZ-based nanoformulations was summarized.


2021 ◽  
pp. 1853-1859
Author(s):  
Yaman Alali ◽  
Muhamed Baljevic

Bortezomib (BTZ) is a proteasome inhibitor used in the treatment of multiple myeloma (MM) and other hematological malignancies. Although carfilzomib, a second-generation proteasome inhibitor, is most strongly associated with cardiotoxicity, BTZ has been associated with several cardiovascular complications including congestive heart failure, arrhythmias, and rarely myocarditis. Here, we report the first case of a BTZ-induced perimyocarditis. The patient was a 40-year-old woman with recently diagnosed MM who was admitted to the hospital with syncope at the start of her second cycle of induction therapy with BTZ, lenalidomide, and dexamethasone. She had a witnessed syncopal event in the emergency room with the telemetry showing sustained ventricular tachycardia. Laboratory workup showed elevated N-terminal pro B-type natriuretic peptide and normal troponin I. Transthoracic echocardiogram (TTE) showed a low ejection fraction of 40% with global hypokinesis of the left ventricle and trace pericardial effusion. Cardiac magnetic resonance imaging with gadolinium was consistent with acute myocarditis. The patient had recurrent pleuritic chest pain, and a repeat TTE showed worsening pericardial effusion consistent with pericarditis. Endomyocardial biopsy was done which showed nonspecific myocyte hypertrophy and foci of fibrosis, but was negative for giant cell myocarditis, hemochromatosis, and amyloidosis. Extensive infectious disease workup ruled out known infectious causes for perimyocarditis. Given the close timing between BTZ treatment (5 subcutaneous doses with a cumulative dose of 6.5 mg/m<sup>2</sup>), the absence of other iatrogenic or infectious causes, and probable or likely association with BTZ as assessed by the validated causality assessment scoring tools, it was concluded that the acute perimyocarditis was secondary to BTZ exposure. Here, we report the first case of BTZ-induced perimyocarditis and discuss the incidence and pathophysiology of BTZ-cardiovascular toxicity.


2021 ◽  
Vol 17 (12) ◽  
pp. e1010058
Author(s):  
Hao Zhang ◽  
Gang Lin

Proteasomes are compartmentalized, ATP-dependent, N-terminal nucleophile hydrolases that play essentials roles in intracellular protein turnover. They are present in all 3 kingdoms. Pharmacological inhibition of proteasomes is detrimental to cell viability. Proteasome inhibitor rugs revolutionize the treatment of multiple myeloma. Proteasomes in pathogenic microbes such as Mycobacterium tuberculosis (Mtb), Plasmodium falciparum (Pf), and other parasites and worms have been validated as therapeutic targets. Starting with Mtb proteasome, efforts in developing inhibitors selective for microbial proteasomes have made great progress lately. In this review, we describe the strategies and pharmacophores that have been used in developing proteasome inhibitors with potency and selectivity that spare human proteasomes and highlight the development of clinical proteasome inhibitor candidates for treatment of leishmaniasis and Chagas disease. Finally, we discuss the future challenges and therapeutical potentials of the microbial proteasome inhibitors.


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