Glutathione S-transferase Alpha-1 Research Articles

GSTA1/CTNNB1 axis facilitates sorafenib resistance via suppressing ferroptosis in hepatocellular carcinoma

The emergence of sorafenib resistance has become a predominant impediment and formidable dilemma in the therapeutic approach for hepatocellular carcinoma (HCC). Although the approval of next-generation drugs as alternatives to sorafenib is a significant development, the concurrent use of inhibitors that target additional key molecular pathways remains an effective strategy to mitigate the acquisition of resistance. Here, we identified Glutathione S-Transferase Alpha 1 (GSTA1) as a critical modulator of sorafenib resistance (SR) in hepatocellular carcinoma (HCC) based on our findings from experiments conducted on recurrent liver cancer tissues, xenograft mouse models, organoids, and sorafenib-resistant cells. Elevated GSTA1 levels are strongly associated with adverse clinical prognoses. The knockout of GSTA1 reinstates sorafenib sensitivity, whereas its overexpression attenuates drug efficacy. Mechanistically, GSTA1 enhances the accumulation of lipid peroxides and suppresses ferroptosis by exerting its peroxidase function to regulate the SR. Notably, the upregulation of GSTA1 expression is mediated by the transcription factor CTNNB1 (β-catenin), resulting in the formation of a cytoplasmic complex between GSTA1 and CTNNB1. This complex facilitates the nuclear translocation of CTNNB1, establishing a positive feedback loop. The combined use of GSTA1 and CTNNB1 inhibitors demonstrated synergistic anti-tumour effects through the induction of ferroptosis both in vitro and in vivo. Our findings reveal a novel regulatory role of the GSTA1/CTNNB1 axis in ferroptosis, suggesting that targeting GSTA1 and CTNNB1 could be a promising strategy to circumvent sorafenib resistance in HCC.

GSTA1 gene polymorphisms are associated with cyclophosphamide effectiveness in lupus nephritis patients: A case-control study in Indonesia

Glutathione-S-transferase alpha-1 (GSTA1) is an enzyme with high conjugation activity against aldophosphamide, a metabolite of cyclophosphamide and promoter polymorphisms in GSTA1 may influence the cyclophosphamide effectiveness. The aim of this study was to evaluate the effectiveness and side effects of cyclophosphamide in lupus nephritis patients, using GSTA1 variants as predictors. A case-control study was conducted at Hasan Sadikin Hospital, Bandung, Indonesia, involving 100 lupus nephritis patients from February 2023 to January 2024. The PCR-Sanger sequencing was used to genotype five selected single nucleotide polymorphisms (SNPs) in the GSTA1 promoter: -52 A>G, -69 T>C, -513 A>G, -567 G>T, and -631 G>T. The endpoint was assessed after six doses of cyclophosphamide by evaluating renal function, disease activity and side effects. Results indicated that six doses of intravenous cyclophosphamide treatment improved renal function and disease activity in the patients, as evidenced by significant changes in serum creatinine (0.79 vs 0.69 mg/dL), dipstick proteinuria (3.00 vs 1.50), creatinine clearance (98.50 vs 109.50 mL/min), and Modified Systemic Lupus Erythematosus Disease Activity Index 2000 (M-SLEDAI-2K) score (8.61 vs 6.95). The AG genotype at -513 A>G was associated with reduced cyclophosphamide effectiveness (odds ratio (OR): 0.19; 95%CI: 0.19–0.60; p=0.019). The GT genotype at -631 G>T independently increased the progression of anemia (OR: 2.41; 95%CI: 0.26–22.12; p=0.040). This study highlights that the presence of GSTA1 variants affected cyclophosphamide effectiveness in lupus nephritis patients, with heterozygous polymorphisms at -513 (AA to AG) and -631 (TT to GT) predicting reduced effectiveness of cyclophosphamide by enhancing GSTA1 promoter activity, while anemia further exacerbated lupus nephritis disease severity. GSTA1 polymorphism was not associated with the presence of alopecia, amenorrhea, gastrointestinal disorders, and leukopenia during cyclophosphamide therapy.

Model-Informed Precision Dosing of Intravenous Busulfan in Thai Pediatrics Undergoing Hematopoietic Stem Cell Transplantation.

Conditioning bifunctional agent, busulfan, is commonly used on children before hematopoietic stem cell transplantation. Currently, at the Ramathibodi hospital, Bangkok, Thailand, initial dosing is calculated according to age and body surface area, and 7 samples per day are used for therapeutic drug monitoring (TDM). This study aimed to identify the best strategies for individual dosages a priori from patient characteristics and a posteriori based on TDM. The pharmacokinetic data set consisted of 2018 plasma concentrations measured in 135 Thai (n = 135) pediatric patients (median age = 8 years) and were analyzed using a population approach. Body weight, presence of malignant disease, and genetic polymorphism of Glutathione S-transferase Alpha-1 (GSTA1) were predictors of clearance. The optimum sampling times for TDM concentration measurements were 0.25, 2, and 5 hours after a 3-hour infusion. This was sufficient to obtain a Bayesian estimate of clearance a posteriori. Simulations showed the poor performance of a priori formula-based dose calculations with 90% of patients demonstrating a 69%-151% exposure interval around the target. This interval shrank to 85%-124% if TDM was carried out only at day 1 and to 90%-116% with TDM at days 1 and 3. This comprehensive study reinforces the interest of TDM in managing interindividual variability in busulfan exposure. Therapeutic drug monitoring can reliably be implemented from 3 samples using the Bayesian approach, preferably over 2 days. If using the latter is not possible, the formulas developed herein could present an alternative in Thai patients.

Upregulation of Hepatic Glutathione S-Transferase Alpha 1 Ameliorates Metabolic Dysfunction-Associated Steatosis by Degrading Fatty Acid Binding Protein 1.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common metabolic disease of the liver, characterized by hepatic steatosis in more than 5% of hepatocytes. However, despite the recent approval of the first drug, resmetirom, for the management of metabolic dysfunction-associated steatohepatitis, decades of target exploration and hundreds of clinical trials have failed, highlighting the urgent need to find new druggable targets for the discovery of innovative drug candidates against MASLD. Here, we found that glutathione S-transferase alpha 1 (GSTA1) expression was negatively associated with lipid droplet accumulation in vitro and in vivo. Overexpression of GSTA1 significantly attenuated oleic acid-induced steatosis in hepatocytes or high-fat diet-induced steatosis in the mouse liver. The hepatoprotective and anti-inflammatory drug bicyclol also attenuated steatosis by upregulating GSTA1 expression. A detailed mechanism showed that GSTA1 directly interacts with fatty acid binding protein 1 (FABP1) and facilitates the degradation of FABP1, thereby inhibiting intracellular triglyceride synthesis by impeding the uptake and transportation of free fatty acids. Conclusion: GSTA1 may be a good target for the discovery of innovative drug candidates as GSTA1 stabilizers or enhancers against MASLD.

Temperature alters the oxidative and metabolic biomarkers and expression of environmental stress-related genes in chocolate mahseer (Neolissochilus hexagonolepis).

Long-term acclimation temperature effects on biomarkers of oxidative stress, metabolic stress, expression of heat shock proteins (Hsps), and warm-temperature acclimation related 65-kDa protein (Wap65) were evaluated in the threatened chocolate mahseer (Neolissochilus hexagonolepis). Fifteen-day-old larvae were acclimated to different water temperatures (15, 19, 23-control group, 27, and 31°C) for 60days prior to the sampling for quantification of mRNA, enzyme, nitric oxide, and malondialdehyde (MDA) content. Acclimation to 31°C increased the basal mRNA level of glutathione S-transferase alpha 1 (GSTa1), and activities of catalase (CAT), glutathione reductase (GR), and GST enzymes and but downregulated the expression of superoxide dismutase 1 (SOD1) in the whole-body homogenate. Other antioxidant genes, i.e., CAT and GPx1a, were unaffected at 31°C, and nitric oxide (NO) concentration was significantly lower. In contrast, fish acclimated to 15°C showed an upregulated transcript level of all the antioxidant genes and no significant difference in the CAT, GR, and GST enzymes. Activities of the metabolic enzymes, aspartate transaminase (AST) and alanine transaminase (ALT), were significantly lower at 15°C. The expression of Hsp47 was upregulated at both 15 and 31°C groups, whereas Hsp70 was elevated at 27 and 31°C groups. Wap65-1 transcription did not show significant variation in treatment groups compared to control. Fish in the high (31°C) and low-temperature (15°C) acclimation groups were capable of maintaining oxidative stress by modulating their antioxidant transcripts, enzymes, and Hsps.

Early loss of glutathione -s- transferase (GST) activity during diverse forms of acute renal tubular injury.

Glutathione‐S‐transferases (GSTs) are a diverse group of phase II detoxification enzymes which primarily evoke tissue protection via glutathione conjugation to xenobiotics and reactive oxygen species. Given their cytoprotective properties, potential changes in GST expression during AKI has pathophysiologic relevance. Hence, we evaluated total GST activity, and the mRNA responses of nine cytosolic GST isotypes (GST alpha1, kappa1, mu1/5, omega1, pi1 sigma1, theta1, zeta1 mRNAs), in five diverse mouse models of AKI (glycerol, ischemia/reperfusion; maleate, cisplatin, endotoxemia). Excepting endotoxemia, each AKI model significantly reduced GST activity (~35%) during both the AKI “initiation” (0‐4 h) and “maintenance” phases (18 or 72 h). During the AKI maintenance phase, increases in multiple GST mRNAs were observed. However, no improvement in GST activity resulted. Increased urinary GST excretion followed AKI induction. However, this could not explain the reduced renal GST activity given that it also fell in response to ex vivo renal ischemia (i.e., absent urinary excretion). GST alpha, a dominant proximal tubule GST isotype, manifested 5–10‐fold protein increases following AKI, arguing against GST proteolysis as the reason for the GST activity declines. Free fatty acids (FFAs) and lysophospholipids, which markedly accumulate during AKI, are known to bind to, and suppress, GST activity. Supporting this concept, arachidonic acid addition to renal cortical protein extracts caused rapid GST activity reductions. Based on these results, we conclude that diverse forms of AKI significantly reduce GST activity. This occurs despite increased GST transcription/translation and independent of urinary GST excretion. Injury‐induced generation of endogenous GST inhibitors, such as FFAs, appears to be a dominant cause.

Garlic oil blocks tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis by inducing phase II drug-metabolizing enzymes

Lung cancer caused one-quarter of all cancer deaths that was more than other cancers. Chemoprevention is a potential strategy to reducing lung cancer incidence and death, and the effective chemopreventive agents are needed. We investigated the efficacy and mechanism of garlic oil (GO), the garlic product, in the chemoprevention of tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung cancer in A/J mice and MRC-5 cell models in the present study. As a result, it was demonstrated that GO significantly inhibited the NNK-induced lung cancer in vivo and protected MRC-5 cells from NNK-induced cell damage. GO could induce the expressions of the phase II drug-metabolizing enzymes, including NAD(P)H: quinone oxidoreductase 1 (NQO-1), glutathione S-transferase alpha 1 (GSTA1), and antioxidative enzymes heme oxygenase-1 (HO-1). These results supported the potential of GO as a novel candidate agent for the chemoprevention of tobacco carcinogens induced lung cancer.

In silico and in vitro investigations on the protein–protein interactions of glutathione S-transferases with mitogen-activated protein kinase 8 and apoptosis signal-regulating kinase 1

Cytosolic glutathione S-transferase (GST) enzymes participate in several cellular processes in addition to facilitating glutathione conjugation reactions that eliminate endogenous and exogenous toxic compounds, especially electrophiles. GSTs are thought to interact with various kinases, resulting in the modulation of apoptotic processes and cellular proliferation. The present research used a combination of in silico and in vitro studies to investigate protein–protein interactions between the seven most abundant cytosolic GSTs—GST alpha-1 (GST-A1), GST alpha-2 (GST-A2), GST mu-1 (GST-M1), GST mu-2 (GST-M2), GST mu-5 (GST-M5), GST theta-1 (GST-T1) and GST pi-1 (GST-P1)—and Mitogen-activated protein kinase 8 (MAPK8) and Apoptosis signal-regulating kinase 1 (ASK1). MAPK8 and ASK1 were chosen as this study’s protein interaction partners because of their predominant role in electrophile or cytokine-induced stress-mediated apoptosis, inflammation and fibrosis. The highest degree of sequence homology or sequence similarity was observed in two GST subgroups: the GST-A1, GST-A2 and GST-P1 isoforms constituted subgroup1; the GST-M1, GST-M2 and GST-M5 isoforms constituted subgroup 2. The GST-T1 isoform diverged from these isoforms. In silico investigations revealed that GST-M1 showed a significantly higher binding affinity to MAPK8, and its complex was more structurally stable than the other isoforms, in the order GST-M1 > GST-M5 > GST-P1 > GST-A2 > GST-A1 > GST-M2 > GST-T1. Similarly, GST-A1, GST-P1 and GST-T1 actively interacted with ASK1, and their structural stability was also better, in the order GST-T1 > GST-A1 > GST-P1 > GST-A2 > GST-M5 > GST-M1 > GST-M2. To validate in silico results, we performed in vitro crosslinking and mass spectroscopy experiments. Results indicated that GST-M1 interacted with GST-T1 to form heterodimers and confirmed the predicted interaction between GST-M1 and MAPK8. Communicated by Ramaswamy H. Sarma

Correlation between hepatic oxidative damage and clinical severity and mitochondrial gene sequencing results in biliary atresia

To assess the level of hepatic oxidative damage and its correlation with clinical severity in biliary atresia (BA), and to understand BA mitochondrial gene sequencing. Forty-eight BA patients and 28 control subjects (20 hepatoblastoma and 8 cholestasis patients) were enrolled. Hepatic oxidative damage was assessed by the expression of oxidation and antioxidant genes, and the correlation between oxidative damage and BA incidence, liver inflammation, and fibrosis was evaluated. Moreover, 8-hydroxyguanine (8-OHdG), mitochondrial DNA (mtDNA) copy number, and mitochondrial gene sequences were determined to evaluate oxidative mtDNA damage in BA. The expression of oxidation gene cytochrome b-245 beta chain (CYBB) in BA was significantly increased and patients with a higher CYBB expression had the higher risk of BA incidence, liver inflammation, and cirrhosis. However, the expression of antioxidant genes was significantly decreased, and glutathione S-transferase alpha 1 (GSTA1) negatively correlated with BA incidence and cirrhosis. When GSTA1 mRNA expression was <0.5487, the sensitivity was 80.85% and the specificity was 80% for BA diagnosis. Moreover, 8-OHdG was increased, whereas mtDNA copy number was significantly decreased in BA. Using mitochondrial gene sequencing, 10 mutation sites were identified, and one family showed a maternal inheritance in genetic loci 15 326. In BA, oxidative damage positively correlated with BA incidence, liver inflammation, and cirrhosis. GSTA1 could be a novel diagnostic indicator. Genetic loci 15 326 could be a maternal genetic mutation site. Taken together, antioxidation therapy after Kasai surgery might have great potential in relieving liver inflammation and fibrosis in BA patients.

Glutathione S‑transferase isozyme alpha 1 is predominantly involved in the cisplatin resistance of common types of solid cancer.

The roles of glutathione S‑transferase pi 1 (GSTP1), glutathione S‑transferase mu 2 (GSTM2) and glutathione S‑transferase alpha 1 (GSTA1) in cisplatin (DDP)‑resistance of solid cancer cells (A549/DDP, SKOV3/DDP and SGC7901/DDP) were compared following expression downregulation with small interfering RNAs (siRNAs). DDP cytotoxicity was reflected by its half maximal inhibition concentration (IC50) calculated from data using a Cell Counting Kit‑8 assay; cell apoptosis was examined using flow cytometry and Hoechst 33342 staining. Higher activities of GST were detected in the cytosol of DDP‑resistant cells, compared with those in the parental DDP‑susceptible cells. The silencing efficacy of each positive siRNA was supported by western blot analysis. GSTP1 silencing resulted in a 4‑fold sensitization of SGC7901/DDP cells to DDP cytotoxicity, but negligible sensitization of SKOV3/DDP and A549/DDP cells. GSTM2 silencing sensitized SKOV3/DDP and A549/DDP cells to DDP cytotoxicity by ~2‑fold, but did not sensitize SGC7901/DDP cells. Notably, GSTA1 silencing enhanced DDP cytotoxicity in SGC7901/DDP cells by 6‑fold, in A549/DDP cells by 5‑fold and in SKOV3/DDP cells by 2‑fold. The combined actions of positive siRNAs and DDP increased the percentages of apoptotic cells in the DDP‑resistant solid cancer cells compared with the combined actions of DDP and the negative siRNAs. The present findings indicated that GSTA1 is a predominant GST isozyme associated with DDP resistance of SGC7901/DDP, A549/DDP and SKOV3/DDP cells; GSTA1‑specific inhibitors may be general sensitizers of SGC7901/DDP, A549/DDP and SKOV3/DDP cells to DDP cytotoxicity through the promotion of cell apoptosis.

Functional GSTA1 Haplotypes Affect Clearance and Toxicity of Busulfan When Administered in 16 Doses to Pediatric Patients Undergoing Hematopoietic Stem Cell Transplantation: A Multicenter Prospective Study on Behalf of the Pediatric Disease Working Party of the European Society for Blood and Marrow Transplantation (EBMT)

Busulfan (BU) dose adjustment following therapeutic drug monitoring (TDM) contributes to better outcome of hematopoietic stem cell transplantation (HSCT). The therapeutic target window can be reached in approximately 51% to 74% of pediatric cases and 45% to 64% of infants depending on the dosing guideline used. We hypothesize that a higher proportion of pediatric patients could achieve the target BU area-under-the-curve (AUC) of 900-1500 µM.min per dose in a four times dosing schedule through genotype-guided initial BU dosing. Previous investigations by our group and others showed association of glutathione -S- transferase alpha 1 (GSTA1) with reduced BU clearance (CL), likely due to altered expression of GSTA1 enzyme, principally involved in BU metabolism.To delineate and investigate the association of each GSTA1 haplotype with the CL of BU, promoter haplotypes of GSTA1 gene were assessed in vitro with reporter gene-assay and clinically in a pediatric multi-center study (N =138) through association with BU CL, AUC, dose change and clinical outcomes. All patients received BU based myeloablative conditioning regimen. BU PK parameters from 1st dose were estimated and further doses were adjusted to have a steady state concentrations of 600-900 ng/mL and GSTA1promoter SNPs at -69, -513, -631, -1142 positions were genotyped using allele specific oligo hybridization method.Reporter-gene assays confirmed significant differences between the haplotype subgroups and supported their importance in capturing PK variability. Four GSTA1 diplotype groups (I-IV) that significantly correlated with CL (p=0.009) were distinguished. GSTA1 diplotypes (group I) underlying fast metabolizing capacity (*A2*A2&*A2*A3) had lower cumulative AUC and a higher dose increase after TDM whereas those with slow metabolizing capacity (group IV, *B1a*B1a /*B1a*B1b /*B2*B1a / *A1*B1b)had highest AUC and least dose change (p=0.02). Multivariate linear model included GSTA1 diplotype groups and non-genetic factors such as age, gender, first BU dose in mg/kg and patients origin. Dose (p<0.0005), gender (p=0.05) and GSTA1 diplotypes (p=0.01) were retained in the final model that explained 34% of overall variability. Analysis with clinical outcomes indicated higher incidences of sinusoidal obstruction syndrome in Group IV diplotype carriers (HR=7.1; 95% CI: 2.5-20.4) compared to patients with other GSTA1diplotypes. A similar association was also seen with acute graft versus host disease (aGvHD grade I-4) and combined treatment-related toxicity (TRT) (p≤0.003).In conclusion, this study has replicated and provided additional evidence for the association of GSTA1 with BU PK and clinical outcomes of HSCT. GSTA1 diplotypes can explain in some models ~20% of the variability seen in BU CL and can contribute to HSCT-related complications acting within and beyond BU metabolism. Genotyping therefore may be helpful in deciding the first BU dose, thus decreasing consequences like TRT due to inaccurate first and subsequent dosing. This may be particularly important for GSTA1 diplotype Group IV carriers. DisclosuresBittencourt:Jazz Pharmaceuticals: Consultancy, Other: Educational Grant; Seattle Genetics: Consultancy.

Investigation of Glutathione S-Transferase Isoenzyme Protein Expression in Patients With Pterygium.

We investigated glutathione S-transferase (GST) enzymes in terms of their potential effects on the pathogenesis of pterygium. Twenty-six pterygium specimens and 15 normal conjunctival specimens of 15 control subjects were investigated. Expressions of GST (alpha, mu, pi, and theta) enzymes were assessed by immunohistochemical staining. A brown color in the cytoplasm and/or nuclei of epithelial cells was evaluated as positive staining for GST enzymes. For each antibody, the intensity of the reaction [negative (-), weak (1+), moderate (2+), or strong (3+)] was determined to describe the immunoreactions. The median age was 52 years in the both groups. There was no significant difference between the groups in terms of age, sex, and intraocular pressure measurements (P > 0.05 for all). Of the 26 pterygium specimens, 15 (57.7%) (8 weak, 4 moderate, and 3 strong staining) were identified with GST pi-1 (GSTP1) expression and 20 (76.9%) (12 weak, 7 moderate, and 1 strong staining) with GST theta-1 (GSTT1) expression. Of the 15 control specimens, 4 (26.7%) (4 weak staining) were identified with the GSTP1 expression, and 1 (6.7%) with GSTT1 expression. GSTP1 and GSTT1 expressions were significantly higher in the pterygium specimens than in the controls (P = 0.043, P < 0.001; respectively). None of tissue specimens had positive staining for GST mu-1 or GST alpha-1 in both groups (both; P = 1.00). The significant increase of GSTP1 and GSTT1 expressions in pterygium may be because of the increased activation of GST in response to excessive free radical formation from ultraviolet exposure to maintain antioxidant capacity in pterygium.

Hepatoprotective effects of Solanum nigrum against ethanol-induced injury in primary hepatocytes and mice with analysis of glutathione S-transferase A1

BackgroundSolanum nigrum is a herbaceous perennial plant, which is widely used in traditional medicine systems for its antioxidant, antiulcerogenic, antitumorigenic, and anti-inflammatory characteristics. The purpose of this study was to investigate the protective effects of S. nigrum against alcoholic liver damage in primary hepatocytes and mice, using glutathione S-transferase alpha 1 (GSTA1) as an indicator. MethodsPrimary hepatocytes were obtained by the inverse perfusion method improved on Seglen two-step perfusion in situ. ResultsIn the presence of S. nigrum aqueous extracts (100 μg/mL), no hepatocytic damage was observed in cells treated with ethanol, compared with the model group, and GSTA1 (p < 0.01) was more sensitive than alanine aminotransferase and aspartate aminotransferase (p < 0.05). Mice that received S. nigrum aqueous extracts (150 mg/kg) with ethanol showed marked attenuation of ethanol-induced hepatotoxicity, as evidenced by significant reductions of serum transaminases (p < 0.01), and variation of hepatic oxidative indices (p < 0.05) and GSTA1 (p < 0.05), compared with the model group and mice that received S. nigrum aqueous extracts (200 mg/kg). All the detection indexes were significantly different (p < 0.01) from those of the model group, and the protective effects were almost the same as that of the positive drug group. ConclusionThese results suggested that S. nigrum has hepatoprotective effects against ethanol-induced injury both in vitro and in vivo, and can protect the integrity of hepatocytes and thus reduce the release of liver GSTA1, which contributes to improved liver detoxification.

Identification of Genes Selectively Regulated in Human Hepatoma Cells by Treatment With Dyslipidemic Sera and PUFAs.

Serum composition is linked to metabolic diseases not only to understand their pathogenesis but also for diagnostic purposes. Quality and quantity of nutritional intake can affect disease risk and serum composition. It is then possible that diet derived serum components directly affect pathogenetic mechanisms. To identify involved factors, we evaluated the effect on gene expression of direct addition of dyslipidemic human serum samples to cultured human hepatoma cells (HepG2). Sera were selected on the basis of cholesterol level, considering this parameter as mostly linked to dietary intake. Cells were treated with 32 sera from hypercholesterolemic and normocholesterolemic subjects to identify differentially regulated mRNAs using DNA microarray analysis. We identified several mRNAs with the highest modulations in cells treated with dyslipidemic sera versus cells treated with normal sera. Since the two serum groups had variable polyunsaturated fatty acids (PUFAs) contents, selected mRNAs were further assessed for their regulation by docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and arachidonic acid (AA). Four genes resulted both affected by serum composition and PUFAs: 3-hydroxy-3-methylglutaryl-CoenzymeA synthase 2 (HMGCS2), glutathione S-transferase alpha 1 (GSTA1), liver expressed antimicrobial peptide 2 (LEAP2) and apolipoprotein M (ApoM). HMGCS2 expression appears the most relevant and was also found modulated via transcription factors peroxysome proliferator activated receptor α (PPARα) and forkhead box O1 (FoxO1). Our data indicate that expression levels of the selected mRNAs, primarily of HMGCS2, could represent a reference of nutritional intake, PUFAs effects and dyslipidemic diseases pathogenesis.

Low Levels of GSTA1 Expression Are Required for Caco-2 Cell Proliferation

The colonic epithelium continuously regenerates with transitions through various cellular phases including proliferation, differentiation and cell death via apoptosis. Human colonic adenocarcinoma (Caco-2) cells in culture undergo spontaneous differentiation into mature enterocytes in association with progressive increases in expression of glutathione S-transferase alpha-1 (GSTA1). We hypothesize that GSTA1 plays a functional role in controlling proliferation, differentiation and apoptosis in Caco-2 cells. We demonstrate increased GSTA1 levels associated with decreased proliferation and increased expression of differentiation markers alkaline phosphatase, villin, dipeptidyl peptidase-4 and E-cadherin in postconfluent Caco-2 cells. Results of MTS assays, BrdU incorporation and flow cytometry indicate that forced expression of GSTA1 significantly reduces cellular proliferation and siRNA-mediated down-regulation of GSTA1 significantly increases cells in S-phase and associated cell proliferation. Sodium butyrate (NaB) at a concentration of 1 mM reduces Caco-2 cell proliferation, increases differentiation and increases GSTA1 activity 4-fold by 72 hours. In contrast, 10 mM NaB causes significant toxicity in preconfluent cells via apoptosis through caspase-3 activation with reduced GSTA1 activity. However, GSTA1 down-regulation by siRNA does not alter NaB-induced differentiation or apoptosis in Caco-2 cells. While 10 mM NaB causes GSTA1-JNK complex dissociation, phosphorylation of JNK is not altered. These findings suggest that GSTA1 levels may play a role in modulating enterocyte proliferation but do not influence differentiation or apoptosis.

Organophosphate pesticides increase the expression of alpha glutathione S-transferase in HepG2 cells

Chlorpyrifos and methyl parathion are among the most widely used insecticides in the world. Human populations are constantly exposed to low doses of both due to their extensive use and presence in food and drinking water. Glutathione S-transferase (GST) catalyzes the conjugation of glutathione on electrophilic substrates and is an important line of defense in the protection of cellular components from reactive species. GST alpha1 (GSTA1) is the predominant isoform of GST expressed in the human liver; thus, determining the effect of insecticides on GSTA1 transcription is very important. In the present study, we analyzed the effects of methyl parathion and chlorpyrifos on GSTA1 gene expression in HepG2 cells using real time PCR, and activity and immunoreactive protein assays. The results demonstrated that exposure to methyl parathion and chlorpyrifos increased the level of GSTA1 mRNA, GSTA1 immunoreactive protein and GST activity relative to a control. These results demonstrated that these insecticides can increase the expression of GSTA1. In conclusion, HepG2 cell cultures treated with methyl parathion and chlorpyrifos could be a useful model for studying the function of GSTA1 and its role in the metabolism of xenobiotics in the liver.

Role of Nrf2 in Protection against Traumatic Brain Injury in Mice

Previous studies have shown that nuclear factor erythroid 2-related factor 2 (Nrf2) plays a unique role in many physiological stress processes. The present study investigated the role of Nrf2 in modulating traumatic brain injury (TBI)-induced secondary brain injury. Wild-type Nrf2 (+/+) and Nrf2 (-/-)-deficient mice were subjected to a moderately severe weight-drop impact head injury. The absence of Nrf2 function in mice resulted in exacerbated brain injury as shown by the increased severity of neurological deficit, apoptosis, and brain edema at 24h after TBI. This exacerbation of brain injury in Nrf2-deficient mice was associated with increased mRNA and protein expression of inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6), and with decreased mRNA expression and enzymatic activity of antioxidant and detoxifying enzymes including NAD(P)H:quinone oxidoreductase 1 (NQO1) and glutathione S-transferase alpha-1 (GST-alpha1), compared with their wild-type counterparts after TBI. In combination, these results suggest that Nrf2 plays an important role in protecting TBI-induced secondary brain injury, possibly by regulating inflammatory cytokines and inducing antioxidant and detoxifying enzymes.

Transcription Factor Nrf2 Plays a Pivotal Role in Protection Against Traumatic Brain Injury-Induced Acute Intestinal Mucosal Injury in Mice

Traumatic brain injury (TBI) can induce an acute intestinal mucosal injury. Nuclear factor erythroid 2-related factor 2 (Nrf2) has a unique role in many physiological stress processes, but its contribution to intestinal mucosal injury after TBI remains to be determined. Wildtype Nrf2 (+/+) and Nrf2 (-/-) deficient mice were subjected to a moderately severe weight-drop impact head injury. Intestinal mucosal morphological changes, plasma endotoxin, intestinal permeability, apoptosis, inflammatory cytokines, and antioxidant/detoxifying enzymes were measured at 24 hours after TBI. Nrf2 deficient mice were found to be more susceptible to TBI-induced acute intestinal mucosal injury, as characterized by the higher increase in gut structure damage, plasma endotoxin, intestinal permeability, and apoptosis after TBI. This exacerbation of intestinal mucosal injury in Nrf2 deficient mice was associated with increased intestinal mRNA and protein expression of inflammatory cytokines such as tumor necrosis factor-alpha, interleukin-1beta and interleukin-6, and with decreased intestinal mRNA expression and activity levels of antioxidant and detoxifying enzymes including NAD(P)H: quinone oxidoreductase 1 (NQO1) and glutathione S-transferase alpha-1 (GST-alpha1), compared with their wildtype Nrf2 (+/+) counterparts after TBI. We show for the first time that mice lacking Nrf2 are more susceptible to TBI-induced acute intestinal mucosal injury. Our data suggests that Nrf2 plays an important role in protecting TBI-induced intestinal mucosal injury, possibly by regulating of inflammatory cytokines and inducing of antioxidant and detoxifying enzymes.

Lung Function in Relation to 2-Thiothiazolidine-4-Carboxylic Acid and Genetic Effect Modification Among Rubber Workers in Sweden

What is the risk of impaired lung function in contemporary Swedish rubber workers and are there modifying effects of genetic variants? Included in the study were 159 rubber exposed and 118 not-rubber exposed workers. Lung function was analyzed as forced vital capacity percent of predicted and forced expiratory volume in 1 second percent of predicted. Levels of 2-thiothiazolidine-4-carboxylic acid (a marker of carbon disulfide and vulcanization fumes) was assessed with liquid chromatography tandem mass spectrometry. Polymorphisms in glutathione-related genes were analyzed by Taqman-based allelic discrimination and ordinary polymerase chain reaction. There was an association between increasing levels of 2-thiothiazolidine-4-carboxylic acid and impaired lung function among exposed workers. The association was modified by glutathione S-transferase alpha 1 (GSTA1)-52 and GSTP1-114. GSTM1 had an influence on lung function among unexposed workers. There may be a risk of impaired lung function in contemporary rubber workers. Gene-modifying effects may be considered in risk assessments.

Influence of glutathione-related genes on symptoms and immunologic markers among vulcanization workers in the southern Sweden rubber industries

The aim was to elucidate the role of genetic variants on symptoms of the eyes and airways, headache and nausea, as well as on immunologic markers, among vulcanization workers in the contemporary Swedish rubber industry. Polymorphisms in genes, which are involved in the defense against reactive oxygen species and metabolism of toxic substances present in the vulcanization fumes, were analyzed. One hundred and forty-five exposed and 117 unexposed workers were included in the study. Medical and occupational histories were obtained in structured interviews. Symptoms were recorded and immunologic markers analyzed in blood. Polymorphisms in glutathione-related genes (glutamate cysteine ligase catalytic subunit (GCLC)-129, glutamate cysteine ligase modifier subunit (GCLM)-588, glutathione S-transferase alpha 1 (GSTA1)-52, GSTM1*O, GSTP1-105, GSTP1-114, and GSTT1*O) were analyzed by Taqman-based allelic discrimination and ordinary PCR. A protective effect of GSTA1-52 (G/A + A/A) genotype on symptoms and immunologic cells, in particular among exposed workers, was suggested. Exposed workers with GSTT1*O had increased risk of nosebleed compared to exposed workers with GSTT1*1. Exposed workers with GSTP1-105 (ile/val + val/val) had decreased levels of total immunoglobulin E (IgE) compared to exposed workers with GSTP1-105 ile/ile. GCLC-129 variant genotype demonstrated increased levels of immunologic cells among exposed workers, although statistical significance was not reached. Our data indicate that hereditary factors influence the susceptibility to symptoms and the immunologic response of workers in the rubber industry.