Targeting the redox vulnerability of acute myeloid leukaemia cells with a combination of auranofin and vitamin C.

Acute myeloid leukaemia (AML) is a heterogeneous disease characterized by complex molecular and cytogenetic abnormalities. Pro-oxidant cellular redox status is a common hallmark of AML cells, providing a rationale for redox-based anticancer strategy. We previously discovered that auranofin (AUF), initially used for the treatment of rheumatoid arthritis and repositioned for its anticancer activity, can synergize with a pharmacological concentration of vitamin C (VC) against breast cancer cell line models. In this study, we observed that this drug combination synergistically and efficiently killed cells of leukaemic cell lines established from different myeloid subtypes. In addition to an induced elevation of reactive oxygen species and ATP depletion, a rapid dephosphorylation of 4E-BP1 and p70S6K, together with a strong inhibition of protein synthesis were early events in response to AUF/VC treatment, suggesting their implication in AUF/VC-induced cytotoxicity. Importantly, a study on 22 primary AML specimens from various AML subtypes showed that AUF/VC combinations at pharmacologically achievable concentrations were effective to eradicate primary leukaemic CD34+ cells from the majority of these samples, while being less toxic to normal cord blood CD34+ cells. Our findings indicate that targeting the redox vulnerability of AML with AUF/VC combinations could present a potential anti-AML therapeutic approach.

Causative Links between Protein Aggregation and Oxidative Stress: A Review.

Compelling evidence supports a tight link between oxidative stress and protein aggregation processes, which are noticeably involved in the development of proteinopathies, such as Alzheimer's disease, Parkinson's disease, and prion disease. The literature is tremendously rich in studies that establish a functional link between both processes, revealing that oxidative stress can be either causative, or consecutive, to protein aggregation. Because oxidative stress monitoring is highly challenging and may often lead to artefactual results, cutting-edge technical tools have been developed recently in the redox field, improving the ability to measure oxidative perturbations in biological systems. This review aims at providing an update of the previously known functional links between oxidative stress and protein aggregation, thereby revisiting the long-established relationship between both processes.

Transcriptional regulation of FeS biogenesis genes: A possible shield against arsenate toxicity activated by Yap1.

In the eukaryotic model yeast Saccharomyces cerevisiae, arsenic (As) detoxification is regulated by two transcriptional factors, Yap8 and Yap1. Yap8 specifically controls As extrusion from the cell, whether Yap1 avoids arsenic-induced oxidative damages. Accordingly, cells lacking both Yap1 and Yap8 are more sensitive to arsenate than cells lacking each regulator individually. Strikingly enough, the same sensitivity pattern was observed under anoxia, suggesting that Yap1 role in As detoxification might not be restricted to the regulation of the oxidative stress response. This finding prompted us to study the transcriptomic profile of wild-type and yap1 mutant cells exposed to arsenate. Interestingly, we found that, under such conditions, several genes involved in the biogenesis of FeS proteins were upregulated in a Yap1-dependent way. In line with this observation, arsenate treatment decreases the activity of the mitochondrial aconitase, Aco1, an FeS cluster-containing enzyme, this effect being even more pronounced in the yap1 mutant. Reinforcing the relevance of FeS cluster biogenesis in arsenate detoxification, the overexpression of several ISC and CIA machinery genes alleviates the deleterious effect of arsenate caused by the absence of Yap1 and Yap8. Altogether our data suggest that the upregulation of FeS biogenesis genes regulated by Yap1 might work as a cellular shield against arsenate toxicity.

Iron-sulfur protein odyssey: exploring their cluster functional versatility and challenging identification.

Iron-sulfur (Fe-S) clusters are an essential and ubiquitous class of protein-bound prosthetic centers that are involved in a broad range of biological processes (e.g. respiration, photosynthesis, DNA replication and repair and gene regulation) performing a wide range of functions including electron transfer, enzyme catalysis, and sensing. In a general manner, Fe-S clusters can gain or lose electrons through redox reactions, and are highly sensitive to oxidation, notably by small molecules such as oxygen and nitric oxide. The [2Fe-2S] and [4Fe-4S] clusters, the most common Fe-S cofactors, are typically coordinated by four amino acid side chains from the protein, usually cysteine thiolates, but other residues (e.g. histidine, aspartic acid) can also be found. While diversity in cluster coordination ensures the functional variety of the Fe-S clusters, the lack of conserved motifs makes new Fe-S protein identification challenging especially when the Fe-S cluster is also shared between two proteins as observed in several dimeric transcriptional regulators and in the mitoribosome. Thanks to the recent development of in cellulo, in vitro, and in silico approaches, new Fe-S proteins are still regularly identified, highlighting the functional diversity of this class of proteins. In this review, we will present three main functions of the Fe-S clusters and explain the difficulties encountered to identify Fe-S proteins and methods that have been employed to overcome these issues.

Safety evaluation of the food enzyme lysophospholipase from the genetically modified Trichoderma reesei strain DP-Nyc81.

The food enzyme lysophospholipase (2-lysophosphatidylcholine acylhydrolase, EC 3.1.1.5) is produced with the genetically modified Trichoderma reesei strain DP-Nyc81 by Genencor International B.V. The genetic modifications do not give rise to safety concerns. The food enzyme is free from viable cells of the production organism and its DNA. It is intended to be used in the processing of cereals and other grains for the production of glucose syrups and other starch hydrolysates. Since residual amounts of food enzyme-total organic solids are removed during these food manufacturing processes, dietary exposure was not calculated and toxicological studies were considered unnecessary. A search for the identity of the amino acid sequence of the food enzyme to known allergens was made and no match was found. The Panel considered that the risk of allergic reactions upon dietary exposure cannot be excluded, but the likelihood is low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

Safety evaluation of an extension of use of the food enzyme thermolysin from the non-genetically modified Anoxybacillus caldiproteolyticus strain AE-TP.

The food enzyme thermolysin (EC. 3.4.24.27) is produced with the non-genetically modified Anoxybacillus caldiproteolyticus strain AE-TP by Amano Enzyme Inc. A safety evaluation of this food enzyme was made previously, in which EFSA concluded that this food enzyme did not give rise to safety concerns when used in eight food manufacturing processes. Subsequently, the applicant has requested to extend its use to one additional process, to withdraw two processes and to revise the use levels. In this assessment, EFSA updated the safety evaluation of this food enzyme for use in a total of seven food manufacturing processes. The dietary exposure to the food enzyme-total organic solids (TOS) was calculated to be up to 0.989 mg TOS/kg body weight (bw) per day in European populations. When combined with the no observed adverse effect level reported in the previous opinion (700 mg TOS/kg bw per day, the mid-dose tested), the Panel derived a revised margin of exposure of at least 708. Based on the data provided for the previous evaluation and the revised margin of exposure in the present evaluation, the Panel concluded that this food enzyme does not give rise to safety concerns under the revised intended conditions of use.

Safety evaluation of an extension of use of the food enzyme oryzin from the non-genetically modified Aspergillus ochraceus strain AE-P.

The food enzyme oryzin (EC 3.4.21.63) is produced with the non-genetically modified Aspergillus ochraceus strain AE-P by Amano Enzyme Inc. A safety evaluation of this food enzyme was made previously, in which EFSA concluded that this food enzyme did not give rise to safety concerns when used in nine food manufacturing processes. Subsequently, the applicant has requested to extend its use to one additional process, to withdraw two food processes and to revise the use levels. In this assessment, EFSA updated the safety evaluation of this food enzyme when used in a total of eight food manufacturing processes. The dietary exposure to the food enzyme-total organic solids (TOS) was calculated to be up to 0.354 mg TOS/kg body weight (bw) per day in European populations. When combined with the no observed adverse effect level reported in the previous opinion (1862 mg TOS/kg bw per day, the highest dose tested), the Panel derived a margin of exposure of at least 5260. Based on the data provided for the previous evaluation and the revised margin of exposure in the present evaluation, the Panel concluded that this food enzyme does not give rise to safety concerns under the revised intended conditions of use.

Regulations of mitoNEET by the key redox homeostasis molecule glutathione.

Human mitoNEET (mNT) and CISD2 are two NEET proteins characterized by an atypical [2Fe-2S] cluster coordination involving three cysteines and one histidine. They act as redox switches with an active state linked to the oxidation of their cluster. In the present study, we show that reduced glutathione but also free thiol-containing molecules such as ß-mercaptoethanol can induce a loss of the mNT cluster under aerobic conditions, while CISD2 cluster appears more resistant. This disassembly occurs through a radical-based mechanism as previously observed with the bacterial SoxR. Interestingly, adding cysteine prevents glutathione-induced cluster loss. At low pH, glutathione can bind mNT in the vicinity of the cluster. These results suggest a potential new regulation mechanism of mNT activity by glutathione, an essential actor of the intracellular redox state.

Safety evaluation of an extension of use of the food enzyme glucan 1,4-α-glucosidase from the non-genetically modified Rhizopus arrhizus strain AE-G.

The food enzyme glucan 1,4-α-glucosidase (4-α-d-glucan glucohydrolase; EC 3.2.1.3) is produced with the non-genetically modified Rhizopus arrhizus strain AE-G by Amano Enzyme Inc. A safety evaluation of this food enzyme was made previously, in which EFSA concluded that this food enzyme did not give rise to safety concerns when used in one food manufacturing process. Subsequently, the applicant requested to extend its use to nine additional processes and revised the use levels. In this assessment, EFSA updated the safety evaluation of this food enzyme for uses in a total of 10 food manufacturing processes. As the food enzyme-total organic solids (TOS) is removed from the final foods in two food manufacturing processes, the dietary exposure to the food enzyme-TOS was estimated only for the remaining eight processes. Dietary exposure was up to 0.424 mg TOS/kg body weight (bw) per day in European populations. When combined with the no observed adverse effect level previously reported (1868 mg TOS/kg bw per day, the highest dose tested), the Panel derived a margin of exposure of at least 4406. Based on the data provided for the previous evaluation and the margin of exposure revised in the present evaluation, the Panel concluded that this food enzyme does not give rise to safety concerns under the revised intended conditions of use.

Safety evaluation of an extension of use of the food enzyme ß-amylase from the non-genetically modified Bacillus flexus strain AE-BAF.

The food enzyme ß-amylase (4-α-d-glucan maltohydrolase, EC 3.2.1.2) is produced with the non-genetically modified Bacillus flexus strain AE-BAF by Amano Enzyme Inc. A safety evaluation of this food enzyme was made previously, in which EFSA concluded that this food enzyme did not give rise to safety concerns when used in three food manufacturing processes. Subsequently, the applicant requested to extend its use to four additional processes and revised the use levels. In this assessment, EFSA updated the safety evaluation of this food enzyme for use in a total of seven food manufacturing processes. As the food enzyme-total organic solids (TOS) are removed from the final foods in one food manufacturing process, the dietary exposure to the food enzyme-TOS was estimated only for the remaining six processes. The dietary exposure was estimated to be up to 0.247 mg TOS/kg body weight per day in European populations. Based on the data provided for the previous evaluation and the dietary exposure revised in the present evaluation, the Panel concluded that this food enzyme does not give rise to safety concerns under the revised intended conditions of use.

Safety evaluation of a food enzyme with phospholipase A1 and lysophospholipase activities from the genetically modified Aspergillus niger strain PLN.

The food enzyme with phospholipase A1 (phosphatidycholine 1-acylhydrolase, EC 3.1.1.32) and lysophospholipase (2-lysophosphatidylcholine acylhydrolase, EC 3.1.1.5) activities is produced with the genetically modified Aspergillus niger strain PLN by DSM. The genetic modifications do not give rise to safety concerns. The food enzyme is free from viable cells of the production organism and its DNA. It is intended to be used for the production of refined edible fats and oils by degumming. Since residual amounts of total organic solids are removed during this process, dietary exposure was not calculated and toxicological studies were considered unnecessary for the assessment of this food enzyme. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and no matches were found. The Panel considered that the risk of allergic reactions upon dietary exposure cannot be excluded, but the likelihood is low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

Safety evaluation of an extension of use of the food enzyme α-amylase from the non-genetically modified Bacillus licheniformis strain AE-TA.

The food enzyme α-amylase (4-α-d-glucan glucanohydrolase; EC 3.2.1.1) is produced with the non-genetically modified microorganism Bacillus licheniformis strain AE-TA by Amano Enzyme Inc. A safety evaluation of this food enzyme was made previously, in which EFSA concluded that this food enzyme did not give rise to safety concerns when used in eight food manufacturing processes. Subsequently, the applicant has requested to extend its use to include one additional process and to revise the use levels. In this assessment, EFSA updated the safety evaluation of this food enzyme when used in a total of nine food manufacturing processes. As the food enzyme-total organic solids (TOS) are removed from the final foods in two food manufacturing processes, the dietary exposure to the food enzyme-TOS was estimated only for the remaining seven processes. Dietary exposure was calculated to be up to 0.382 mg TOS/kg body weight per day in European populations. Based on the data provided for the previous evaluation and the revised dietary exposure in the present evaluation, the Panel concluded that this food enzyme does not give rise to safety concerns under the revised intended conditions of use.

Safety evaluation of an extension of use of the food enzyme triacylglycerol lipase from the non-genetically modified Rhizopus arrhizus strain AE-TL(B).

The food enzyme triacylglycerol lipase (triacylglycerol acylhydrolase; EC 3.1.1.3) is produced with the non-genetically modified Rhizopus arrhizus strain AE-TL(B) by Amano Enzyme Inc. A safety evaluation of this food enzyme was made previously, in which EFSA concluded that this food enzyme did not give rise to safety concerns when used in two food manufacturing processes. Subsequently, the applicant requested to extend its use to include four additional processes and to revise the use levels. In this assessment, EFSA updated the safety evaluation of this food enzyme when used in a total of six food manufacturing processes. As the food enzyme-total organic solids (TOS) are removed from one food manufacturing process, the dietary exposure to the food enzyme-TOS was estimated only for the remaining five processes. Dietary exposure was calculated to be up to 0.086 mg TOS/kg body weight (bw) per day in European populations. When combined with the no observed adverse effect level reported in the previous opinion (1960 mg TOS/kg bw per day, the highest dose tested), the Panel derived a margin of exposure of at least 22,791. Based on the data provided for the previous evaluation and the revised margin of exposure in the present evaluation, the Panel concluded that this food enzyme does not give rise to safety concerns under the revised intended conditions of use.

Safety evaluation of an extension of use of the food enzyme bacillolysin from the non-genetically modified Bacillus amyloliquefaciens strain AE-NP.

The food enzyme bacillolysin (EC 3.4.24.28) is produced with the non-genetically modified Bacillus amyloliquefaciens strain AE-NP by Amano Enzyme Inc. A safety evaluation of this food enzyme was made previously, in which EFSA concluded that this food enzyme did not give rise to safety concerns when used in thirteen food manufacturing processes. Subsequently, the applicant requested to extend its use to two additional processes. In this assessment, EFSA updated the safety evaluation of this food enzyme when used in a total of fifteen food manufacturing processes. As the food enzyme-total organic solids (TOS) are removed in two food manufacturing processes, the dietary exposure to the food enzyme-TOS was estimated only for the remaining thirteen processes. Dietary exposure was calculated to be up to 35.251 mg TOS/kg body weight per day in European populations. Based on the data provided for the previous evaluation and the revised dietary exposure in the present evaluation, the Panel concluded that this food enzyme does not give rise to safety concerns under the revised intended conditions of use.

Safety evaluation of an extension of use of the food enzyme 4-α-glucanotransferase from the non-genetically modified Aeribacillus pallidus strain AE-SAS.

The food enzyme 4-α-glucanotransferase (1,4-α-d-glucan:1,4-α-d-glucan 4-α-d-glycosyltransferase, EC 2.4.1.25) is produced with the non-genetically modified Aeribacillus pallidus strain AE-SAS by Amano Enzyme Inc. A safety evaluation of this food enzyme was made previously, in which EFSA concluded that this food enzyme did not give rise to safety concerns when used in two food manufacturing processes. Subsequently, the applicant requested to extend its use to two additional processes. In this assessment, EFSA updated the safety evaluation of this food enzyme for use in a total of four food manufacturing processes. As the food enzyme-total organic solids (TOS) is removed from the final foods in one food manufacturing process, the dietary exposure to the food enzyme-TOS was estimated only for the remaining three processes. Dietary exposure was up to 0.040 mg TOS/kg body weight (bw) per day in European populations. When combined with the no observed adverse effect level reported in the previous opinion (900 mg TOS/kg bw per day, the highest dose tested), the Panel derived a margin of exposure of at least 22,500. Based on the data provided for the previous evaluation and the revised margin of exposure, the Panel concluded that this food enzyme does not give rise to safety concerns under the revised intended conditions of use.

Safety evaluation of an extension of use of the food enzyme endo-polygalacturonase from the genetically modified Aspergillus oryzae strain AR-183.

The food enzyme endo-polygalacturonase ((1 → 4)-α-d-galacturonan glycanohydrolase EC 3.2.1.15) is produced with the genetically modified Aspergillus oryzae strain AR-183 by AB ENZYMES GmbH. A safety evaluation of this food enzyme was made previously, in which EFSA concluded that this food enzyme did not give rise to safety concerns when used in five food manufacturing processes. Subsequently, the applicant requested to extend its use to two additional processes. In this assessment, EFSA updated the safety evaluation of this food enzyme for use in a total of seven food manufacturing processes. As the food enzyme-total organic solids (TOS) is removed from the final foods in three food manufacturing processes, the dietary exposure to the food enzyme-TOS was estimated only for the remaining four processes. Dietary exposure was up to 0.087 mg TOS/kg body weight (bw) per day in European populations. When combined with the NOAEL reported in the previous opinion (1000 mg TOS/kg bw per day, the highest dose tested), the Panel derived a margin of exposure of at least 11,494. Based on the data provided for the previous evaluation and the revised margin of exposure, the Panel concluded that this food enzyme does not give rise to safety concerns under the revised intended conditions of use.

Safety evaluation of an extension of use of the food enzyme pectinesterase from the genetically modified Aspergillus oryzae strain AR-962.

The food enzyme pectinesterase (pectin pectylhydrolase; EC 3.1.1.11) is produced with the genetically modified Aspergillus oryzae strain AR-962 by AB Enzymes GmbH. A safety evaluation of this food enzyme was made previously, in which EFSA concluded that this food enzyme did not give rise to safety concerns when used in five food manufacturing processes. Subsequently, the applicant requested to extend its use to two additional processes. In this assessment, EFSA updated the safety evaluation of this food enzyme for uses in a total of seven food manufacturing processes. As the food enzyme-total organic solids (TOS) is removed from the final foods in three food manufacturing processes, the dietary exposure to the food enzyme-TOS was estimated only for the remaining four processes. Dietary exposure was up to 0.575 mg TOS/kg body weight (bw) per day in European populations. When combined with the NOAEL reported in the previous opinion (1000 mg TOS/kg bw per day, the highest dose tested), the Panel derived a margin of exposure of at least 1739. Based on the data provided for the previous evaluation and the revised margin of exposure, the Panel concluded that this food enzyme does not give rise to safety concerns under the revised intended conditions of use.

Safety evaluation of the food enzyme subtilisin from the genetically modified Bacillus licheniformis strain NZYM-CB.

The food enzyme subtilisin (EC 3.4.21.62) is produced with the genetically modified Bacillus licheniformis strain NZYM-CB by Novozymes A/S. The genetic modifications do not give rise to safety concerns. The food enzyme is considered free from viable cells of the production organism and its DNA. It is intended to be used in six food manufacturing processes. The dietary exposure to the food enzyme-TOS was estimated to be up to 0.722 mg TOS/kg body weight (bw) per day in European populations. The production strain of the food enzyme fulfils the requirements for the qualified presumption of safety approach to safety assessment. As no other concerns arising from the manufacturing process were identified, the Panel considered that toxicological tests were not required for the assessment of this food enzyme. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and 20 matches were found, including two food allergens (melon and pomegranate). The Panel considered that the risk of allergic reactions by dietary exposure cannot be excluded, particularly in individuals sensitised to melon and pomegranate, but would not exceed the risk from consumption of melon or pomegranate. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Safety evaluation of an extension of use of the food enzyme ß-glucosidase from the non-genetically modified Penicillium guanacastense strain AE-GLY.

The food enzyme ß-glucosidase (ß-d-glucoside glucohydrolase, EC 3.2.1.21) is produced with the non-genetically modified Penicillium guanacastense strain AE-GLY by Amano Enzyme Inc. A safety evaluation of this food enzyme was made previously, in which EFSA concluded that this food enzyme did not give rise to safety concerns when used in four food manufacturing processes. Subsequently, the applicant has requested to extend its use to include three additional processes and to revise the use levels. In this assessment, EFSA updated the safety evaluation of this food enzyme when used in a total of seven food manufacturing processes. The dietary exposure was calculated to be up to 0.206 mg total organic solids (TOS)/kg body weight (bw) per day in European populations. Using the no observed adverse effect level reported in the previous opinion (943 mg TOS/kg bw per day), the Panel derived a margin of exposure of at least 4578. Based on the previous evaluation, the assessment of the new data and the revised margin of exposure, the Panel concluded that this food enzyme does not give rise to safety concerns under the revised intended conditions of use.

Safety evaluation of the food enzyme endonuclease from the non-genetically modified Penicillium citrinum strain NP 11-15.

The food enzyme endonuclease (Aspergillus nuclease S1; EC 3.1.30.1) is produced with the non-genetically modified Penicillium citrinum strain NP 11-15 by Shin Nihon Chemical Co., Ltd. The food enzyme is free from viable cells of the production organism. It is intended to be used in the processing of yeast and yeast products. Dietary exposure to the food enzyme-total organic solids (TOS) was estimated to be up to 0.006 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 1010 mg TOS/kg bw per day, the highest dose tested, which when compared with the estimated dietary exposure, resulted in a margin of exposure of at least 168,333. A search for homology of the amino acid sequence of the food enzyme to known allergens was made and no match was found. The Panel considered that the risk of allergic reactions by dietary exposure cannot be excluded, especially for individuals allergic to Penicillium. However, the likelihood of such reactions will not exceed the likelihood of allergic reactions to Penicillium. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.