Induction of Tumor Cell Apoptosis by a Proteasome Deubiquitinase Inhibitor Is Associated with Oxidative Stress

Brnjic, Slavica; Mazurkiewicz, Magdalena; Fryknäs, Mårten; Sun, Chao; Zhang, Xiaonan; Larsson, Rolf; D’Arcy, Pádraig; Linder, Stig

doi:10.1089/ars.2013.5322

Cited by 66 publications

(96 citation statements)

References 66 publications

(96 reference statements)

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“…Blocking of proteasome function is known to induce the expression of a cellular chaperone response, induction of ER stress and oxidative stress (8,30–33). Microarray analysis showed that VLX1570 induces chaperone expression (HSPA6, HSPA1L, HSPA4L), the oxidative stress marker HMOX1 [known to be induced by bortezomib (34)], and the ER stress-associated marker DDIT3/CHOP in MCF7 cancer cells (Table S3).…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Evaluation of Derivatives of the Proteasome Deubiquitinase Inhibitor b‐AP15

et al. 2015

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The ubiquitin–proteasome system (UPS) is increasingly recognized as a therapeutic target for the development of anticancer therapies. The success of the 20S proteasome core particle (20S CP) inhibitor bortezomib in the clinical management of multiple myeloma has raised the possibility of identifying other UPS components for therapeutic intervention. We previously identified the small molecule b-AP15 as an inhibitor of 19S proteasome deubiquitinase (DUB) activity. Building upon our previous data, we performed a structure–activity relationship (SAR) study on b-AP15 and identified VLX1570 as an analog with promising properties, including enhanced potency and improved solubility in aqueous solution. In silico modeling was consistent with interaction of VLX1570 with key cysteine residues located at the active sites of the proteasome DUBs USP14 and UCHL5. VLX1570 was found to inhibit proteasome deubiquitinase activity in vitro in a manner consistent with competitive inhibition. Furthermore, using active-site-directed probes, VLX1570 also inhibited proteasome DUB activity in exposed cells. Importantly, VLX1570 did not show inhibitory activity on a panel of recombinant non-proteasome DUBs, on recombinant kinases, or on caspase-3 activity, suggesting that VLX1570 is not an overtly reactive general enzyme inhibitor. Taken together, our data shows the chemical and biological properties of VLX1570 as an optimized proteasome DUB inhibitor.

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Section: Resultsmentioning

confidence: 99%

Synthesis and Evaluation of Derivatives of the Proteasome Deubiquitinase Inhibitor b‐AP15

et al. 2015

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“…Considering that USP14 and UCHL5 belong to different classes of DUBs, dual inhibition of these enzymes by small molecules would a priori be expected to be possible only in the context of broad-spectrum DUB inhibition. Recently however, a number of compounds have been described that preferentially inhibit proteasomal DUB activity compared to other cytosolic that also inhibits proteasomal deubiquitinase activity resulting in a similar stress response and cytotoxicity profile (Brnjic et al, 2014;Coughlin et al, 2014). Another pair of structurally related compounds, G5 and F6, initially identified in a screen for agents that induce apoptosis Bcl-2 over-expressing cells; were subsequently shown to be potent inhibitors of general DUB activity leading to acute proteotoxic stress and apoptosis (Aleo et al, 2006).…”

Section: Proteasomal Dubs As Drug Targets For Cancer Therapymentioning

confidence: 99%

“…This difference in synergy observed is presumably due to the irreversible binding of carfilzomib to the proteasome compared to the slowly reversible nature of bortezomib. sufficient to perturb bortezomib-induced apoptosis (Brnjic et al, 2014;D'Arcy et al, 2011).…”

Section: Mechanisms Of Resistance To Bortezomib and Other Inhibitors mentioning

confidence: 99%

Inhibition of proteasome deubiquitinase activity: a strategy to overcome resistance to conventional proteasome inhibitors?

Selvaraju

Mazurkiewicz

Wang

et al. 2015

Drug Resistance Updates

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The ubiquitin-proteasome system (UPS) is the primary mechanism controlling the degradation of damaged, unwanted or short-lived proteins in eukaryotic cells. In addition to protein homeostasis, the UPS has also emerged as a critical node in the regulation of signalling pathways implicated in the growth and survival of cancer cells. The absolute dependency of cancer cells on a functioning UPS has been exploited in the development of anti-cancer therapies as exemplified by development of proteasome inhibitors for the treatment of certain leukemic malignancies.Deubiquitinases (DUBs) are enzyme components of the UPS that catalyse re-editing of poly ubiquitin chains and/or removal of ubiquitin en bloc from target substrates leading to alterations in protein stability and/or downstream signalling. There is a growing recognition that targeting DUB activity may be a feasible option for the development of novel anti-cancer therapies. In particular inhibition of proteasomal cysteine DUBs (i.e. USP14 and UCHL5) has been shown to be particularly cytotoxic to cancer cells leading to the accumulation of ubiquitinated proteins and proteotoxic stress. In this review we focus on the mechanisms of action of proteasome DUB inhibitors as well as the potential of such compounds to circumvent acquired drug resistance in cancer patients.

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“…These results demonstrate that AgDT-triggered DUB inhibition is not dependent on ROS production. It has been believed that generation of cellular ROS is associated with proteasome inhibitorinduced cell death [41,42]. Proteasome inhibition leads to accumulation of misfolded proteins in the endoplasmic reticulum (ER) and thereby induces ER stress, which may cause the accumulation of ROS [43,44].…”

Section: Discussionmentioning

confidence: 99%

Inhibition of Proteasomal Deubiquitinase by Silver Complex Induces Apoptosis in Non-Small Cell Lung Cancer Cells

Chen

Yang

Chen

et al. 2018

Cell Physiol Biochem

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Background/Aims: The ubiquitin proteasome system (UPS) is responsible for the degradation of most intracellular proteins, and proteasomal deubiquitinases (DUBs) have recently been highlighted as novel anticancer targets. It is well documented that copper complexes can inhibit UPS function through targeting both 20S proteasome and proteasomal DUBs. The antineoplastic activities of silver complexes have received much attention, but the exact mechanisms are not fully elucidated. In this study, we aim to investigate the effects of a novel silver complex [Ag(S₂CN(C₂H₅)₂)]₆ (AgDT) on UPS function and its anticancer potential in non-small cell lung cancer (NSCLC). Methods: Cell viability assay (i.e., the MTS assay) and flow cytometry assay were used to analyze the cell viability and apoptosis. Proteasome inhibition was measured using 20S proteasome activity assay and 19S proteasomal DUBs activity assay. Western blot analysis and immunohistochemistry were performed to detect protein levels. The in vivo antitumor activity of AgDT was assessed with nude xenografts. Results: Silver ions, alone or in combination with disulfiram (DSF), induced UPS inhibition in NSCLC cells mainly through inhibition of proteasomal DUBs activities. Silver complex AgDT triggered intracellular accumulation of ubiquitinated proteins, and prevented the degradation of surrogate substrate GFPu. Mechanistically, AgDT potently inhibited the activities of proteasomal DUBs USP14 and UCHL5, without altering the 20S proteasome peptidases. Moreover, AgDT induced apoptosis in NSCLC cells and significantly inhibited tumor growth in xenografts. Conclusion: Our findings suggest that silver complex AgDT is a novel metal-based proteasomal DUBs inhibitor, and pharmacologic inhibition of USP14 and UCHL5 could prove to be an effective therapeutic strategy for NSCLC.

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Induction of Tumor Cell Apoptosis by a Proteasome Deubiquitinase Inhibitor Is Associated with Oxidative Stress

Abstract: Our data show that enhanced oxidative stress and ER stress are major determinants of the strong apoptotic response elicited by the 19S DUB inhibitor b-AP15.

Cited by 66 publications

References 66 publications

Synthesis and Evaluation of Derivatives of the Proteasome Deubiquitinase Inhibitor b‐AP15

Synthesis and Evaluation of Derivatives of the Proteasome Deubiquitinase Inhibitor b‐AP15

Inhibition of proteasome deubiquitinase activity: a strategy to overcome resistance to conventional proteasome inhibitors?

Inhibition of Proteasomal Deubiquitinase by Silver Complex Induces Apoptosis in Non-Small Cell Lung Cancer Cells

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