- Irreversible inhibition of cytosolic thioredoxin reductase 1 as a mechanistic basis for anticancer therapy. [Journal Article]
- STSci Transl Med 2018 Feb 14; 10(428)
- Cancer cells adapt to their inherently increased oxidative stress through activation of the glutathione (GSH) and thioredoxin (TXN) systems. Inhibition of both of these systems effectively kills canc...
Cancer cells adapt to their inherently increased oxidative stress through activation of the glutathione (GSH) and thioredoxin (TXN) systems. Inhibition of both of these systems effectively kills cancer cells, but such broad inhibition of antioxidant activity also kills normal cells, which is highly unwanted in a clinical setting. We therefore evaluated targeting of the TXN pathway alone and, more specifically, selective inhibition of the cytosolic selenocysteine-containing enzyme TXN reductase 1 (TXNRD1). TXNRD1 inhibitors were discovered in a large screening effort and displayed increased specificity compared to pan-TXNRD inhibitors, such as auranofin, that also inhibit the mitochondrial enzyme TXNRD2 and additional targets. For our lead compounds, TXNRD1 inhibition correlated with cancer cell cytotoxicity, and inhibitor-triggered conversion of TXNRD1 from an antioxidant to a pro-oxidant enzyme correlated with corresponding increases in cellular production of H2O2In mice, the most specific TXNRD1 inhibitor, here described as TXNRD1 inhibitor 1 (TRi-1), impaired growth and viability of human tumor xenografts and syngeneic mouse tumors while having little mitochondrial toxicity and being better tolerated than auranofin. These results display the therapeutic anticancer potential of irreversibly targeting cytosolic TXNRD1 using small molecules and present potent and selective TXNRD1 inhibitors. Given the pronounced up-regulation of TXNRD1 in several metastatic malignancies, it seems worthwhile to further explore the potential benefit of specific irreversible TXNRD1 inhibitors for anticancer therapy.
- The antioxidant 2,6-di-tert-butylphenol moiety attenuates the pro-oxidant properties of the auranofin analogue. [Journal Article]
- MMetallomics 2018 Feb 05
- Metal-based drugs are gaining momentum as a rapidly developing area of medicinal inorganic chemistry. Among gold pharmaceuticals, auranofin is a well known antirheumatic drug. The efficacy of gold-or...
Metal-based drugs are gaining momentum as a rapidly developing area of medicinal inorganic chemistry. Among gold pharmaceuticals, auranofin is a well known antirheumatic drug. The efficacy of gold-organic complexes largely depends on their pro-oxidant properties since auranofin targets the redox enzyme thioredoxin reductase (TrxR). However, an uncontrollable oxygen burst may be harmful for healthy cells; therefore, the search for chemical modifications to attenuate oxidation-related general toxicity of gold containing anti-inflammatory drugs is justified. In this study, we demonstrate that the incorporation of a specific antioxidant phenol fragment can counterbalance the pro-oxidative potential of the Au containing complex molecule. The electrochemical studies of AuPPh3SR (1, R= 3,5-di-tert-butyl-4-hydroxyphenyl) and its precursors AuPPh3Cl (2) and RSH (3) showed that complex 1 and phenol 3 efficiently scavenged the radicals (as detected by cyclic voltammetry) whereas 2 had no effect. Compound 1 inhibited TrxR in vitro with IC500.57 ± 0.15 μM, a value one order of magnitude bigger than the potency reported for auranofin. Compound 1 (5 mg kg-1daily gavage for 14 days) caused a decrease in ex vivo spontaneous and ascorbate-induced lipid peroxidation in the homogenates of rat lung, heart muscle, spleen, liver, kidneys, testicles and brain as assessed by the thiobarbituric acid reactive substances. Importantly, in animals fed with 1, no discernible general toxicity was registered suggesting that this compound is well tolerated. Our results provide evidence for an efficient synthetic route to obtain gold containing anti-inflammatory drug candidates with balanced pro/anti-oxidative properties.
- TDP-43 self-interaction is modulated by redox-active compounds Auranofin, Chelerythrine and Riluzole. [Journal Article]
- SRSci Rep 2018 Feb 02; 8(1):2248
- Amyotrophic lateral sclerosis (ALS) represents a fatal neurodegenerative disease, which is characterized by a rapid loss of lower and upper motor neurons. As a major neuropathological hallmark, prote...
Amyotrophic lateral sclerosis (ALS) represents a fatal neurodegenerative disease, which is characterized by a rapid loss of lower and upper motor neurons. As a major neuropathological hallmark, protein aggregates containing the Transactivating Response Region (TAR) DNA Binding Protein (TDP-43) are detectable in about 95% of sporadic ALS patients. TDP-43 interacts with itself physiologically to form liquid droplets, which may progress to pathological aggregates. In this study, we established the NanoBit luciferase complementation assay to measure TDP-43 self-interaction and found the fusion of the split luciferase subunits to the N-terminus of the protein as the strongest interacting partners. A screen of pharmacologically active compounds from the LOPAC®1280library identified auranofin, chelerythrine and riluzole as dose-dependent inhibitors of TDP-43 self-interaction. Further analysis of drug action of the gold-containing thioredoxin reductase inhibitor auranofin revealed a redistribution from insoluble TDP-43 protein pool to PBS-soluble protein pool in N2a cells. In addition, auranofin treatment diminished reduced glutathione as a sign for oxidative modulation.
- Elimination of stem-like cancer cell side-population by auranofin through modulation of ROS and glycolysis. [Journal Article]
- CDCell Death Dis 2018 Jan 24; 9(2):89
- Cancer side-population (SP) represents a sub-population of stem-like cancer cells that have an important role in drug resistance due to their high expression of the ATP-binding cassette transporter A...
Cancer side-population (SP) represents a sub-population of stem-like cancer cells that have an important role in drug resistance due to their high expression of the ATP-binding cassette transporter ABCG2 involved in drug export. Auranofin (AF), a clinical drug of gold complex that is used in treatment of rheumatoid arthritis, has been reported inducing tumor antiproliferation. However, whether AF can impact SP cells remains unclear. Our study showed that AF caused a depletion of SP cells and a downregulation of stem cell markers, and impaired their ability to form tumor colonies in vitro and incidence to develop tumors in vivo of lung cancer cells. Reactive oxygen species (ROS) had an important role in mediating AF-induced depletion of SP cells, which could be reversed by antioxidant NAC. Further study revealed that AF could also cause ATP depletion by inhibition of glycolysis. The depletion of cellular ATP might impair the function of ABCG2 pump, leading to increased drug accumulation within the cells and thus enhancing anticancer activity of chemotherapeutic agents such as adriamycin. Synergistic effect of AF and adriamycin was demonstrated both in vitro and in vivo. Simultaneous increase of ROS and inhibition of glycolysis is a novel strategy to eliminate stem-like cancer cells. Combination of AF with adriamycin seems to be promising to enhance therapeutic effectiveness.
- Biomarkers of tumour redox status in response to modulations of glutathione and thioredoxin antioxidant pathways. [Journal Article]
- FRFree Radic Res 2018 Jan 31; :1-11
- The ability of certain cancer cells to maintain a highly reduced intracellular environment is correlated with aggressiveness and drug resistance. Since the glutathione (GSH) and thioredoxin (TRX) sys...
The ability of certain cancer cells to maintain a highly reduced intracellular environment is correlated with aggressiveness and drug resistance. Since the glutathione (GSH) and thioredoxin (TRX) systems cooperate to a tight regulation of ROS in cell physiology, and to a stimulation of tumour initiation and progression, modulation of the GSH and TRX pathways are emerging as new potential targets in cancer. In vivo methods to assess changes in tumour redox status are critically needed to assess the relevance of redox-targeted agents. The current study assesses in vitro and in vivo biomarkers of tumour redox status in response to treatments targeting the GSH and TRX pathways, by comparing cytosolic and mitochondrial redox nitroxide electron paramagnetic resonance (EPR) probes, and cross-validation with redox dynamic fluorescent measurement. For that purpose, the effect of the GSH modulator buthionine sulfoximine (BSO) and of the TRX reductase inhibitor auranofin were measured in vitro using both cytosolic and mitochondrial EPR and roGFP probes in breast and cervical cancer cells. In vivo, mice bearing breast or cervical cancer xenografts were treated with the GSH or TRX modulators and monitored using the mito-TEMPO spin probe. Our data highlight the importance of using mitochondria-targeted spin probes to assess changes in tumour redox status induced by redox modulators. Further in vivo validation of the mito-tempo spin probe with alternative in vivo methods should be considered, yet the spin probe used in vivo in xenografts demonstrated sensitivity to the redox status modulators.
- The possible repositioning of an oral anti-arthritic drug, auranofin, for Nrf2-activating therapy: The demonstration of Nrf2-dependent anti-oxidative action using a zebrafish model. [Journal Article]
- FRFree Radic Biol Med 2018 Feb 01; 115:405-411
- The Nrf2 pathway is a biological defense system against oxidative stress. The pharmacological activation of the Nrf2 pathway is a promising therapy for oxidative stress-related diseases, but it has b...
The Nrf2 pathway is a biological defense system against oxidative stress. The pharmacological activation of the Nrf2 pathway is a promising therapy for oxidative stress-related diseases, but it has been challenging to find an Nrf2 activator with acceptable toxicity. To circumvent this problem, we focused on an already approved oral anti-arthritic drug, auranofin that has been reported to have the potential to activate Nrf2. We used a zebrafish model to investigate whether auranofin has protective action against oxidative stress in vivo. Auranofin pre-treatment considerably improved the survival of zebrafish larvae that were challenged with a lethal dose of hydrogen peroxide. This protective effect was not observed in an Nrf2 mutant zebrafish strain, suggesting that the activation of the biological defense against oxidative stress was Nrf2-dependent. Auranofin-induced protection was further tested by challenges with redox-active heavy metals. A clear protective effect was observed against arsenite, a highly redox-reactive toxicant. In addition, this effect was also demonstrated to be Nrf2-dependent based on the analysis of an Nrf2 mutant strain. These results clearly demonstrate the anti-oxidative action of auranofin and encourage the repositioning of auranofin as a drug that improves oxidative stress-related pathology.
- An automated high-throughput system for phenotypic screening of chemical libraries on C. elegans and parasitic nematodes. [Journal Article]
- IJInt J Parasitol Drugs Drug Resist 2017 Dec 02; 8(1):8-21
- Parasitic nematodes infect hundreds of millions of people and farmed livestock. Further, plant parasitic nematodes result in major crop damage. The pipeline of therapeutic compounds is limited and pa...
Parasitic nematodes infect hundreds of millions of people and farmed livestock. Further, plant parasitic nematodes result in major crop damage. The pipeline of therapeutic compounds is limited and parasite resistance to the existing anthelmintic compounds is a global threat. We have developed an INVertebrate Automated Phenotyping Platform (INVAPP) for high-throughput, plate-based chemical screening, and an algorithm (Paragon) which allows screening for compounds that have an effect on motility and development of parasitic worms. We have validated its utility by determining the efficacy of a panel of known anthelmintics against model and parasitic nematodes: Caenorhabditis elegans, Haemonchus contortus, Teladorsagia circumcincta, and Trichuris muris. We then applied the system to screen the Pathogen Box chemical library in a blinded fashion and identified compounds already known to have anthelmintic or anti-parasitic activity, including tolfenpyrad, auranofin, and mebendazole; and 14 compounds previously undescribed as anthelmintics, including benzoxaborole and isoxazole chemotypes. This system offers an effective, high-throughput system for the discovery of novel anthelmintics.
- Selection and characterization of a human ovarian cancer cell line resistant to auranofin. [Journal Article]
- OOncotarget 2017 Nov 10; 8(56):96062-96078
- The anti-arthritic drug auranofin exerts also potent antitumour activity in in vitro and in vivo models, whose mechanisms are not yet well defined. From an auranofin-sensitive human ovarian cancer ce...
The anti-arthritic drug auranofin exerts also potent antitumour activity in in vitro and in vivo models, whose mechanisms are not yet well defined. From an auranofin-sensitive human ovarian cancer cell line A2780, a highly resistant (>20-fold) subline (A2780/AF-R) was developed and characterized. Marked reduction of gold accumulation occurred in auranofin-resistant A2780 cells. Also, moderately higher thioredoxin reductase activity in A2780/AF-R cells was observed while no changes in intracellular glutathione content occurred. Resistance to auranofin was associated with a low level of cross-resistance to some investigational gold compounds as well as to oxaliplatin and other anticancer drugs with different mode of action (i.e. melphalan, vinblastine, doxorubicin, etoposide, and paclitaxel). Reduced gold accumulation was associated to substantial gene expression changes in various influx (e.g. SLC22A1, SLC47A1, SLCO1B1) and efflux (e.g. ABCB1, ABCC2, ABCC3) transporters. The expression levels of selected proteins (i.e. SLC22A1, SLC47A1, P-gp) were also changed accordingly. These data provide evidence that multiple drug transporters may act as mediators of transport of auranofin and other gold compounds in cancer cells. Further investigation into the molecular mechanisms mediating transport of auranofin and new gold complexes in view of their potential clinical application in the treatment of cancer is warranted.
- Auranofin, a thioredoxin reductase inhibitor, causes platelet death through calcium overload. [Journal Article]
- PPlatelets 2017 Dec 01; :1-7
- Platelets are central to normal hemostasis and must be tightly controlled to prevent thrombosis. However, drug treatments that also affect platelets could lead to unwanted side effects on hemostasis ...
Platelets are central to normal hemostasis and must be tightly controlled to prevent thrombosis. However, drug treatments that also affect platelets could lead to unwanted side effects on hemostasis or thrombosis. In this study, the effect of auranofin on platelets was tested. Auranofin, a gold-based thioredoxin reductase (TRXR) inhibitor, has been previously used in arthritis. Recently, auranofin and other inhibitors of the thioredoxin system have been proposed as novel anti-cancer therapies. TRXR is an important part of the antioxidant defenses in many cells that maintain intracellular proteins in their reduced state. TRXR activity in platelets could be completely inhibited by auranofin. Auranofin-treated platelets showed several features of cell death, including the inability to aggregate in response to thrombin, leakage of cytosolic lactate dehydrogenase, and surface exposure of procoagulant phosphatidylserine. Auranofin increased platelet reactive oxygen species production and intracellular calcium concentration. DTT, a sulfydyl reducing agent, and BAPTA-AM, which chelates intracellular calcium, prevented auranofin-induced phosphatidylserine exposure. These data suggest that TRXR is an important part of the platelet antioxidant defense. TRXR inhibition by auranofin triggers oxidative stress and disrupts intracellular calcium homeostasis, leading to platelet necrosis. The use of auranofin or other TRXR inhibitors could therefore lead to unwanted side effects.
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- Annexin A5 suppresses cyclooxygenase-2 expression by downregulating the protein kinase C-ζ-nuclear factor-κB signaling pathway in prostate cancer cells. [Journal Article]
- OOncotarget 2017 Sep 26; 8(43):74263-74275
- Annexin A5 (ANXA5) is a member of the annexin protein family. Previous studies have shown that ANXA5 is involved in anti-inflammation and cell death. However, the detailed mechanism of the role of AN...
Annexin A5 (ANXA5) is a member of the annexin protein family. Previous studies have shown that ANXA5 is involved in anti-inflammation and cell death. However, the detailed mechanism of the role of ANXA5 in cancer cells is not well understood. In this study, we investigated the inhibitory effect of ANXA5 on cyclooxygenase-2 (COX-2) in prostate cancer cells. Expression of COX-2 induced by TNF-α was inhibited by overexpression of ANXA5 and inhibition of COX-2 expression by auranofin, which could induce ANXA5 expression, was restored by ANXA5 knockdown. In addition, ANXA5 knockdown induces phosphorylation of NF-κB p65 in prostate cancer cells, indicating that ANXA5 causes COX-2 downregulation through inhibition of p65 activation. We also found that protein kinase C (PKC)-ζ protein levels were upregulated by the inhibition of ANXA5, although the mRNA levels were unaffected. We have shown that upregulated COX-2 expression by inhibition of ANXA5 is attenuated by PKC-ζ siRNA. In summary, this study demonstrates that downregulation of PKC-ζ-NF-κB signaling by ANXA5 may inhibit COX-2 expression in prostate cancer.