The Antioxidant 3H-1,2-Dithiole-3-Thione Potentiates Advanced Glycation End-Product-Induced Oxidative Stress in SH-SY5Y Cells

Oxidative stress is implicated as a major factor in the development of diabetes complications and is caused in part by advanced glycation end products (AGEs). AGEs ligate to the receptor for AGEs (RAGE), promoting protein kinase C (PKC)-dependent activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and superoxide radical generation. While scavenging antioxidants are protective against AGEs, it is unknown if induction of endogenous antioxidant defenses has the same effect. In this study, we confirmed that the compound 3H-1,2-dithiole-3-thione (D3T) increases reduced-state glutathione (GSH) concentrations and NADPH:quinone oxidoreductase 1 (NQO1) activity in SH-SY5Y cells and provides protection against H2O2. Surprisingly, D3T potentiated oxidative damage caused by AGEs. In comparison to vehicle controls, D3T caused greater AGE-induced cytotoxicity and depletion of intracellular GSH levels while offering no protection against neurite degeneration or protein carbonylation. D3T potentiated AGE-induced reactive oxygen species (ROS) formation, an effect abrogated by inhibitors of PKC and NADPH oxidase. This study suggests that chemical induction of endogenous antioxidant defenses requires further examination in models of diabetes

Quantitative trait mapping in Diversity Outbred mice identifies novel genomic regions associated with the hepatic glutathione redox system.

The tripeptide glutathione (GSH) is instrumental to antioxidant protection and xenobiotic metabolism, and the ratio of its reduced and oxidized forms (GSH/GSSG) indicates the cellular redox environment and maintains key aspects of cellular signaling. Disruptions in GSH levels and GSH/GSSG have long been tied to various chronic diseases, and many studies have examined whether variant alleles in genes responsible for GSH synthesis and metabolism are associated with increased disease risk. However, past studies have been limited to established, canonical GSH genes, though emerging evidence suggests that novel loci and genes influence the GSH redox system in specific tissues. The present study marks the most comprehensive effort to date to directly identify genetic loci associated with the GSH redox system. We employed the Diversity Outbred (DO) mouse population, a model of human genetics, and measured GSH and the essential redox cofactor NADPH in liver, the organ with the highest levels of GSH in the body. Under normal physiological conditions, we observed substantial variation in hepatic GSH and NADPH levels and their redox balances, and discovered a novel, significant quantitative trait locus (QTL) on murine chromosome 16 underlying GSH/GSSG; bioinformatics analyses revealed Socs1 to be the most likely candidate gene. We also discovered novel QTL associated with hepatic NAD

Cultivation of circulating tumor cells in esophageal cancer

The presence of circulating tumor cells (CTCs) in patients with metastatic carcinoma is generally associated with poor clinical outcome. There have been many investigations showing a possible use of CTCs as minimally invasive predictive and prognostic biomarker in cancer medicine. In this report a size-based method (MetaCell®) for quick and easy enrichment and cultivation of CTCs is presented to enable possible CTCs use in esophageal cancer (EC) management. In total, 43 patients with diagnosed EC, 20 with adenocarcinoma (AdenoCa) and 23 with squamous cell carcinoma (SCC), were enrolled into the adaptive prospective-like study .All the patients were candidates for surgery. The CTCs were detected in 27 patients (62.8%), with a higher rate in adenocarcinoma (75%) than SCC (52%). Finally, there were 26 patients with resectable tumors exhibiting CTCs-positivity in 69.2% and 17 patients with non-resectable tumors with 41.7% CTCs-positivity. Interestingly, in the patients undergoing neoadjuvant therapy, the CTCs were detected at time of surgery in 55.5% (10/18). The overall size-based filtration approach enabled to isolate viable CTCs and evaluate to their cytomorphological features by means of vital fluorescent staining. The CTCs were cultured in vitro for further downstream applications including immunohistochemical analysis. This is the first report of the successful culturing of esophageal cancer CTCs. The detection of CTCs presence could help in the future to guide timing of surgical treatment in EC patients

The role of scavenging antioxidants and the transcription factor NRF2 in protection against advanced glycation end products in a neuronal-derived cell line

Oxidative stress is implicated as a causal factor for diabetes-associated tissue complications. Cell and animal models of diabetes complications show an overall protective benefit of antioxidant treatments. Oxidative stress is achieved through several ROS-producing mechanisms in diabetes, so attention should be given to antioxidants that consistently show positive effects across several mechanisms of damage. In these studies, a cell culture model of diabetic neuropathy was used to test whether the lipid soluble antioxidant α-tocopherol or manipulation of intracellular GSH concentrations resulted in protection against AGEs. In our initial studies, α-tocopherol was relatively limited in its effects as it lowered lipid peroxidation and cell death but it had no effect on neurite degeneration and intracellular antioxidant status. Treatment with NAC had a pronounced effect by improving cell viability and maintaining neurite structure, which were observed with a concomitant increase in GSH. We next tested whether increasing GSH by chemically inducing activity of the transcription factor Nrf2 conferred benefit to cells exposed to AGEs. While the prototypical Nrf2-inducing antioxidant D3T protected against H2O 2, it surprisingly potentiated AGE-induced oxidative damage. The results demonstrated that effects of Nrf2 induction on oxidative damage depend heavily on the source of stress and mechanism of activation

Impact of Supplementary Amino Acids, Micronutrients, and Overall Diet on Glutathione Homeostasis

Glutathione (GSH) is a critical endogenous antioxidant found in all eukaryotic cells. Higher GSH concentrations protect against cellular damage, tissue degeneration, and disease progression in various models, so there is considerable interest in developing interventions that augment GSH biosynthesis. Oral GSH supplementation is not the most efficient option due to the enzymatic degradation of ingested GSH within the intestine by γ-glutamyltransferase, but supplementation of its component amino acids—cysteine, glycine, and glutamate—enhances tissue GSH synthesis. Furthermore, supplementation with some non-precursor amino acids and micronutrients appears to influence the redox status of GSH and related antioxidants, such as vitamins C and E, lowering systemic oxidative stress and slowing the rate of tissue deterioration. In this review, the effects of oral supplementation of amino acids and micronutrients on GSH metabolism are evaluated. And since specific dietary patterns and diets are being prescribed as first-line therapeutics for conditions such as hypertension and diabetes, the impact of overall diets on GSH homeostasis is also assessed

JR: The antioxidant 3H-1,2-dithiole-3-thione potentiates advanced glycation end-product-induced oxidative stress in SH-SY5Y cells. Experimen- tal diabetes research 2012:137607

Oxidative stress is implicated as a major factor in the development of diabetes complications and is caused in part by advanced glycation end products (AGEs). AGEs ligate to the receptor for AGEs (RAGE), promoting protein kinase C (PKC)-dependent activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and superoxide radical generation. While scavenging antioxidants are protective against AGEs, it is unknown if induction of endogenous antioxidant defenses has the same effect. In this study, we confirmed that the compound 3H-1,2-dithiole-3-thione (D3T) increases reduced-state glutathione (GSH) concentrations and NADPH:quinone oxidoreductase 1 (NQO1) activity in SH-SY5Y cells and provides protection against H 2 O 2 . Surprisingly, D3T potentiated oxidative damage caused by AGEs. In comparison to vehicle controls, D3T caused greater AGE-induced cytotoxicity and depletion of intracellular GSH levels while offering no protection against neurite degeneration or protein carbonylation. D3T potentiated AGE-induced reactive oxygen species (ROS) formation, an effect abrogated by inhibitors of PKC and NADPH oxidase. This study suggests that chemical induction of endogenous antioxidant defenses requires further examination in models of diabetes

Murine Adipose Tissue-Derived Stromal Cell Apoptosis and Susceptibility to Oxidative Stress <i>In Vitro</i> Are Regulated by Genetic Background

<div><p>Adipose tissue-derived stromal cells (ADSCs) are of interest for regenerative medicine as they are isolated easily and can differentiate into multiple cell lineages. Studies of their <i>in vitro</i> proliferation, survival, and differentiation are common; however, genetic effects on these phenotypes remain unknown. To test if these phenotypes are genetically regulated, ADSCs were isolated from three genetically diverse inbred mouse strains- C57BL/6J (B6), BALB/cByJ (BALB), and DBA/2J (D2)- in which genetic regulation of hematopoietic stem function is well known. ADSCs from all three strains differentiated into osteogenic and chondrogenic lineages <i>in vitro</i>. ADSCs from BALB grew least well <i>in vitro</i>, probably due to apoptotic cell death after several days in culture. BALB ADSCs were also the most susceptible to the free radical inducers menadione and H₂O₂. ADSCs from the three possible F1 hybrids were employed to further define genetic regulation of ADSC phenotypes. D2, but not B6, alleles stimulated ADSC expansion in BALB cells. In contrast, B6, but not D2, alleles rescued BALB H₂O₂ resistance. We conclude that low oxidative stress resistance does not limit BALB ADSC growth <i>in vitro</i>, as these phenotypes are genetically regulated independently. In addition, ADSCs from these strains are an appropriate model system to investigate genetic regulation of ADSC apoptosis and stress resistance in future studies. Such investigations are essential to optimize cell expansion and differentiation and thus, potential for regenerative medicine.</p> </div

Effects of genetic background on ADSC oxidative stress resistance.

<p>MTT assays were performed to assess the cell viability of B6, BALB, and D2 ADSCs following treatment with menadione (A), paraquat (B), and H₂O₂ (C). Data are expressed as mean ± S.E. (<i>n</i> = 3 for menadione; <i>n</i> = 5–6 for H₂O₂; *<i>P</i><0.05 vs. B6 and D2 and **<i>P</i><0.01 vs. B6 and D2). Cell viabilities of F1 hybrid ADSCs were measured by MTT assay after treatment with H₂O₂ (D). Data are expressed as mean ± S.E. (<i>n</i> = 5–6; *<i>P</i><0.05 vs. B6D2F1 and CByB6F1; **<i>P</i><0.01 vs. B6D2F1 and CByB6F1). BALB ADSCs were treated with and without 4.0 mM NAC in growth media for 10 days and apoptosis was measured (E). Data are expressed as percentages of Annexin-V⁺ cells that are either positive or negative for PI (<i>n</i> = 5–7, *<i>P</i><0.05).</p