Higher Frequency of Glutathione S-Transferase Deletions in Black Children With Acute Lymphoblastic Leukemia

Arsenic compounds activate MAPK and inhibit Akt pathways to induce apoptosis in MA-10 mouse Leydig tumor cells

Arsenic compounds have been applied treating acute promyelocytic 1eukemia and solid tumors with brief mechanism investigations. In fact, we have demonstrated that sodium arsenite plus dimethylarsenic acid could activate apoptosis in MA-10 mouse Leydig tumor cells by inducing caspase pathways. However, detail underlying mechanisms how caspase cascade is regulated remains elusive. Therefore, the apoptotic mechanism of sodium arsenite plus dimethylarsenic acid were examined in MA-10 cells in this study. Our results reveal that Fas/FasL protein expressions were stimulated by sodium arsenite plus dimethylarsenic acid in MA-10 cells. In addition, reactive oxygen species (ROS) generation, cytochrome C release, Bid truncation, and Bax translocation were induced in MA-10 cells by arsenic compounds. Moreover, activation of p38, JNK and ERK1/2, MAPK pathways was stimulated while Akt phosphorylated levels and Akt expression were decreased by sodium arsenite plus dimethylarsenic in MA-10 cells. In conclusion, sodium arsenite and dimethylarsenic acid did activate MAPK pathway plus ROS generation, but suppress Akt pathway, to modulate caspase pathway and then induce MA-10 cell apoptosis.

Maternal obesity and acute lymphoblastic leukemia risk in offspring: A summary of trends, epidemiological evidence, and possible biological mechanisms

Acute lymphoblastic leukemia, a heterogenous malignancy characterized by uncontrolled proliferation of lymphoid progenitors and generally initiated in utero, is the most common pediatric cancer. Although incidence of ALL has been steadily increasing in recent decades, no clear reason for this trend has been identified. Rising concurrently with ALL incidence, increasing maternal obesity rates may be partially contributing to increasing ALL prevelance. Epidemiological studies, including a recent meta-analysis, have found an association between maternal obesity and leukemogenesis in offspring, although mechanisms underlying this association remain unknown. Therefore, the purpose of this review is to propose possible mechanisms connecting maternal obesity to ALL risk in offspring, including changes to fetal/neonatal epigenetics, altered insulin-like growth factor profiles and insulin resistance, modified adipokine production and secretion, changes to immune cell populations, and impacts on birthweight and childhood obesity/adiposity. We describe how each proposed mechanism is biologically plausible due to their connection with maternal obesity, presence in neonatal and/or fetal tissue, observation in pediatric ALL patients at diagnosis, and association with leukemogenesis, A description of ALL and maternal obesity trends, a summary of epidemiological evidence, a discussion of the pathway from intrauterine environment to subsequent malignancy, and propositions for future directions are also presented.

Bcl-2 hijacks the arsenic trioxide resistance in SH-SY5Y cells

Aresenic trioxide (ATO) is proven to be active against leukaemia cells by inducing apoptosis and differentiation. Even though ATO could effectively induce remissions of leukaemia cells, the drug resistance was observed occasionally. To further dissect the mechanism of ATO resistance, we selected the ATO-resistant SH-SY5Y cells and found that Bcl-2 controlled the sensitivity of ATO in SH-SY5Y cells. We report that necroptosis, autophagy, NF-ƘB and MAPK signalling pathway are not involved in ATO-induced apoptosis. Moreover, the ATO-resistant cells showed distinct mitochondrial morphology compared with that of ATO-sensitive cells. Intriguingly, nude mice-bearing ATO-sensitive cells derived xenograft tumours are more sensitive to ATO treatment compared with that of ATO-resistant cells. These data demonstrate that cancer cells can acquire the ATO-resistance ability by increasing the Bcl-2 expression.

GSTT1 null and rs156697 Polymorphism in GSTO2 Influence the Risk and Therapeutic Outcome of B-Acute Lymphoblastic Leukemia Patients

INTRODUCTION

Glutathione S-transferase (GST) gene deletion or polymorphic sequence variations lead to decreased enzyme activity that influences susceptibility and response to chemotherapy in acute lymphoblastic leukemia (ALL). This case-control study investigated the association of GST gene polymorphisms with the etiology and therapeutic outcome of B-ALL among Kashmiri population.

METHODS

A total of 300 individuals including 150 newly diagnosed B-ALL patients and an equal number of age and gender matched controls were genotyped for five GST gene polymorphisms by polymerase chain reaction-restriction fragment length polymorphism technique (PCR-RFLP) and multiplex PCR techniques.

RESULTS

Higher frequency of GSTT1 null, GSTO2-AG, and GSTO2-GG genotypes was observed in ALL cases compared to controls that associated significantly with ALL risk (GSTT1 null: OR = 2.93, p = 0.0001; GSTO2-AG: OR = 2.58, p = 0.01; GSTO2-GG: OR = 3.13, p = 0.01). GSTM1, GSTP1, and GSTO1 SNPs showed no significant association (p > 0.05). Combined genotype analysis revealed significant association of GSTT1 null/GSTM1 null (OR = 4.11, p = 0.011) and GSTT1 null/GSTP1-AG (OR = 4.93, p = 0.0003) with B-ALL susceptibility. Haplotype analysis of rs4925 and rs156697 revealed that carriers of CG haplotype had increased risk of B-ALL (p = 0.04). Kaplan-Meier plots revealed significantly inferior 3-year disease-free survival for GSTO2-GG carriers (p = 0.002). Multivariate analysis confirmed GSTO2-GG as an independent poor prognostic factor for DFS (HR = 4.5, p = 0.034). Among combined genotypes, only GSTT1 null/GSTP1-AG associated significantly with poorer DFS rates (p = 0.032).

CONCLUSION

This study demonstrated that GSTT1 null individually or in combination with GSTM1null and GSTP1-AG genotypes associated with increased B-ALL risk. Also, rs156697 variant genotypes (AG and GG) associated with B-ALL, whereas the GG genotype of rs156697 influenced the treatment outcome.

GSTM1 and GSTT1 double null genotypes determining cell fate and proliferation as potential risk factors of relapse in children with hematological malignancies after hematopoietic stem cell transplantation

PURPOSE

This study aimed to retrospectively evaluate the genetic association of null variants of glutathione S-transferases GSTM1 and GSTT1 with relapse incidence in children with hematological malignancies (HMs) undergoing busulfan (BU)- containing allogeneic hematopoietic stem cell transplantation (HSCT) and to assess the impact of these variants on BU-induced cytotoxicity on the immortalized lymphoblastoid cell lines (LCLs) and tumor THP1 GST gene-edited cell models.

METHODS

GSTM1- and GSTT1-null alleles were genotyped using germline DNA from whole blood prior to a conditioning BU-based regimen. Association of GSTM1- and GSTT1-null variants with relapse incidence was analyzed using multivariable competing risk analysis. BU-induced cell death studies were conducted in GSTs- null and non-null LCLs and CRISPR-Cas9 gene-edited THP1 leukemia cell lines.

RESULTS

Carrying GSTM1/GSTT1 double null genotype was found to be an independent risk factor for post-HSCT relapse in 86 children (adjusted HR: 6.52 [95% Cl, 2.76-15.42; p = 1.9 × 10^-5]). BU-induced cell death preferentially in THP1^{GSTM1(non-null)} and LCLs^{GSTM1(non-null)} as shown by decreased viability, increased necrosis and levels of the oxidized form of glutathione compared to null cells, while GSTT1 non-null cells showed increased baseline proliferation.

CONCLUSION

The clinical association suggests that GSTM1/GSTT1 double null genotype could serve as genetic stratification biomarker for the high risk of post-HSCT relapse. Functional studies have indicated that GSTM1 status modulates BU-induced cell death. On the other hand, GSTT1 is proposed to be involved in baseline cell proliferation.

Arsenic trioxide reduces the expression of E2F1, cyclin E, and phosphorylation of PI3K signaling molecules in acute leukemia cells

Arsenic trioxide (ATO) has been used for the treatment of acute promyelocytic leukemia (APL). Although ATO modulates cell cycle progression and apoptosis in APL cells, its exact mechanism of action remains elusive. In this research, we investigated its effects on E2F1, cyclin E, p53, pRb, and PI3K signaling molecules by western blotting, immunocytochemistry and/or confocal imaging. We found that ATO inhibited the proliferation of APL cells through down-regulation of E2F1 and cyclin E expression, and stimulation of pRb. It also reduced the interaction of pRb and E2F1with binding to the E2F1 promoter, by stimulating pRb association. ATO also effected the phosphorylation of pRb at S608 and T373 residues and association of E2F1, pRb, and p53, simultaneously. However, in p53-knockdown NB4 cells, ATO did not significantly reduce E2F1 and cyclin E expression. Our findings demonstrate that ATO inhibits APL cell growth through reduced expression of E2F1, cyclin E, and stimulation of pRb. It also effected both interaction and association of E2F1, pRb, and p53 by phosphorylation of pRb at T373 and S608 residues and reduced phosphorylation of PI3K signaling molecules. This novel mode of action of ATO in APL cells may be useful for designing new APL drugs.

Fluorescent probes for in vitro and in vivo quantification of hydrogen peroxide

Hydrogen peroxide (H2O2) plays essential roles in redox signaling and oxidative stress, and its dynamic concentration is critical to human health and diseases. Here we report the design, syntheses, and biological applications of HKPerox-Red and HKPerox-Ratio for quantitative measurement of H2O2. Both probes were successfully applied to detect endogenous H2O2 fluxes in living cells or zebrafish, and biological effects of multiple stress inducers including rotenone, arsenic trioxide, and starvation were investigated. As H2O2 is a common by-product for oxidase oxidation, a general assay was developed for ultrasensitive detection of various metabolites (glucose, uric acid, and sarcosine). Moreover, cellular H2O2 measurements were achieved for the first time by combining flow cytometry with live cell calibration. This study provides a pair of unique molecular tools for advanced H2O2 bio-imaging and assay development.

A Highly Selective and Sensitive Chemiluminescent Probe for Real-Time Monitoring of Hydrogen Peroxide in Cells and Animals

Selective and sensitive molecular probes for hydrogen peroxide (H₂ O₂ ), which plays diverse roles in oxidative stress and redox signaling, are urgently needed to investigate the physiological and pathological effects of H₂ O₂ . A lack of reliable tools for in vivo imaging has hampered the development of H₂ O₂ mediated therapeutics. By combining a specific tandem Payne/Dakin reaction with a chemiluminescent scaffold, H₂ O₂ -CL-510 was developed as a highly selective and sensitive probe for detection of H₂ O₂ both in vitro and in vivo. A rapid 430-fold enhancement of chemiluminescence was triggered directly by H₂ O₂ without any laser excitation. Arsenic trioxide induced oxidative damage in leukemia was successfully detected. In particular, cerebral ischemia-reperfusion injury-induced H₂ O₂ fluxes were visualized in rat brains using H₂ O₂ -CL-510, providing a new chemical tool for real-time monitoring of H₂ O₂ dynamics in living animals.

ATO (Arsenic Trioxide) Effects on Promyelocytic Leukemia Nuclear Bodies Reveals Antiviral Intervention Capacity

Human adenoviruses (HAdV) are associated with clinical symptoms such as gastroenteritis, keratoconjunctivitis, pneumonia, hepatitis, and encephalitis. In the absence of protective immunity, as in allogeneic bone marrow transplant patients, HAdV infections can become lethal. Alarmingly, various outbreaks of highly pathogenic, pneumotropic HAdV types have been recently reported, causing severe and lethal respiratory diseases. Effective drugs for treatment of HAdV infections are still lacking. The repurposing of drugs approved for other indications is a valuable alternative for the development of new antiviral therapies and is less risky and costly than de novo development. Arsenic trioxide (ATO) is approved for treatment of acute promyelocytic leukemia. Here, it is shown that ATO is a potent inhibitor of HAdV. ATO treatment blocks virus expression and replication by reducing the number and integrity of promyelocytic leukemia (PML) nuclear bodies, important subnuclear structures for HAdV replication. Modification of HAdV proteins with small ubiquitin-like modifiers (SUMO) is also key to HAdV replication. ATO reduces levels of viral SUMO-E2A protein, while increasing SUMO-PML, suggesting that ATO interferes with SUMOylation of proteins crucial for HAdV replication. It is concluded that ATO targets cellular processes key to HAdV replication and is relevant for the development of antiviral intervention strategies.

Glutathione S-transferase M1 and T1 genes deletion polymorphisms and risk of developing essential hypertension: a case-control study in Burkina Faso population (West Africa)

BACKGROUND

Glutathione S-transferases play a key role in the detoxification of persistent oxidative stress products which are one of several risks factors that may be associated with many types of disease processes such as cancer, diabetes, and hypertension. In the present study, we characterize the null genotypes of GSTM1 and GSTT1 in order to investigate the association between them and the risk of developing essential hypertension.

METHODS

We conducted a case-control study in Burkina Faso, including 245 subjects with essential hypertension as case and 269 control subjects with normal blood pressure. Presence of the GSTT1 and GSTM1 was determined using conventional multiplex polymerase chain reaction followed by gel electrophoresis analysis. Biochemical parameters were measured using chemistry analyzer CYANExpert 130.

RESULTS

Chi-squared test shows that GSTT1-null (OR = 1.82; p = 0.001) and GSTM1-active/GSTT1-null genotypes (OR = 2.33; p <  0.001) were significantly higher in cases than controls; the differences were not significant for GSTM1-null, GSTM1-null/GSTT1-active and GSTM1-null/GSTT1-null (p > 0.05). Multinomial logistic regression revealed that age ≥ 50 years, central obesity, family history of hypertension, obesity, alcohol intake and GSTT1 deletion were in decreasing order independent risk factors for essential hypertension. Analysis by gender, BMI and alcohol showed that association of GSTT1-null with risk of essential hypertension seems to be significant when BMI < 30 Kg/m², in non-smokers and in alcohol users (all OR ≥ 1.77; p ≤ 0.008). Concerning GSTT1, GSTM1 and cardiovascular risk markers levels in hypertensive group, we found that subjects with GSTT1-null genotype had higher waist circumference and higher HDL cholesterol level than those with GSTT1-active (all p <  0.005), subjects with GSTM1-null genotype had lower triglyceride than those with GSTM1-active (p = 0.02) and subjects with the double deletion GSTM1-null/GSTT1-null had higher body mass index, higher waist circumference and higher HDL cholesterol than those with GSTM1-active/GSTT1-active genotype (all p = 0.01).

CONCLUSION

Our results confirm that GSTT1-null genotype is significantly associated with risk of developing essential hypertension in Burkinabe, especially when BMI < 30 Kg/m², in non-smokers and in alcohol users, and it showed that the double deletion GSTM1-null/GSTT1-null genotypes may influence body lipids repartition.

Glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) variants and breast cancer risk in Burkina Faso

Background and objective

Breast cancer remains the most common cause of cancer mortality in women. The aim of this study was to investigate associations between genetic variability in GSTM1 and GSTT1 and susceptibility to breast cancer.

Methods

Genomic DNA was extracted from blood samples for 80 cases of histologically diagnosed breast cancer and 100 control subjects. Genotyping analyses were performed by PCR-based methods. Associations between specific genotypes and the development of breast cancer were examined using logistic regression to calculate odds ratios [1] and 95% confidence intervals (95%CI).

Results

No correlation was found between GSTM1-null and breast cancer (OR = 1.83; 95%CI 0.90-3.71; p = 0.10), while GSTT1-null (OR = 2.42; 95%CI 1.17-5.02; p= 0.01) was associated with increased breast cancer risk. The GSTM1/GSTT1 double null was not associated with an increased risk of developing breast cancer (OR = 2.52; 95%CI 0.75-8.45; p = 0.20). Furthermore, analysis found no association between GSTM1-null (OR =1.12; 95%CI 0.08-15.50; p = 1.00) or GSTT1-null (OR = 1.71; 95%CI 0.13-22.51; p = 1.00) and the disease stage of familial breast cancer patients or sporadic breast cancer patients (GSTM1 (OR = 0.40; 95%CI 0.12-1.32; p = 0.20) and GSTT1 (OR = 1.41; 95%CI 0.39-5.12; p = 0.75)). Also, body mass index (BMI) was not associated with increased or decreased breast cancer risk in either GSTM1-null (OR = 0.60; 95%CI 0.21-1.68; p = 0.44) or GSTT1-null (OR = 0.60; 95%CI 0.21-1.68; p =0.45).

Conclusion

Our results suggest that only GSTT1-null is associated with increased susceptibility to breast cancer development.

Study of the mechanisms of crocetin-induced differentiation and apoptosis in human acute promyelocytic leukemia cells

Crocetin, the major carotenoid in saffron, exhibits potent anticancer effects. However, the antileukemic effects of crocetin are still unclear, especially in primary acute promyelocytic leukemia (APL) cells. In the current study, the potential antipromyelocytic leukemia activity of crocetin and the underlying molecular mechanisms were investigated. Crocetin (100 µM), like standard anti-APL drugs, all-trans retinoic acid (ATRA, 10 µM) and As₂ O ₃ (arsenic trioxide, 50 µM), significantly inhibited proliferation and induced apoptosis in primary APL cells, as well as NB4 and HL60 cells. The effect was associated with the decreased expressions of prosurvival genes Akt and BCL2, the multidrug resistance (MDR) proteins, ABCB1 and ABCC1 and the inhibition of tyrosyl-DNA phosphodiesterase 1 (TDP1), while the expressions of proapoptotic genes CASP3, CASP9, and BAX/BCL2 ratio were significantly increased. In contrast, crocetin at relatively low concentration (10 µM), like ATRA (1 µM) and As ₂ O ₃ (0.5 µM), induced differentiation of leukemic cells toward granulocytic pattern, and increased the number of differentiated cells expressing CD11b and CD14, while the number of the immature cells expressing CD34 or CD33 was decreased. Furthermore, crocetin suppressed the expression of clinical marker promyelocytic leukemia/retinoic acid receptor-α ( PML/RARα) in NB4 and primary APL cells, and reduced the expression of histone deacetylase 1 ( HDAC1) in all leukemic cells. The results suggested that crocetin can be considered as a candidate for future preclinical and clinical trials of complementary APL treatment.

GSTT1 Null Genotype and Susceptibility to Children Acute Leukemia in Chinese Population: Evidence from a Meta-Analysis

Objectives:

Increasing number of studies has focused on studying the relationship between glutathione S-transferase T1 polymorphism and children acute leukemia, among which discrepancies have risen. The aim of this study is to provide a more exact assessment of glutathione S-transferase T1 polymorphism and children acute leukemia among certain Chinese population.

Methods:

Studies were identified using PubMed, Springer Link, Ovid, Chinese Wanfang Data Knowledge Service Platform, Chinese National Knowledge Infrastructure and Chinese Biology Medicine from beginning to July 2018. The strength of association was quantified by pooling odds ratios and 95% confidence intervals using fixed-effect or random-effect model according to the heterogeneity.

Results:

Overall, a positive relationship was found in null genotype of glutathione S-transferase T1 polymorphism on the risk of childhood acute leukemia among all Chinese populations (odds ratios: 1.52; 95% confidence intervals = 1.19-1.94). Similarly, consistent results were found in subgroup of Southern China (odds ratios: 1.48; 95% confidence intervals: 1.08-2.02), Northern China (odds ratios: 1.59; 95% confidence intervals: 1.09-2.33), acute lymphoblastic leukemia (odds ratios: 1.61; 95% confidence intervals: 1.19-2.17), “age > 18 years” (odds ratios: 1.59; 95% confidence intervals: 1.09-2.33), “age < 18 years” (odds ratios: 1.48; 95% confidence intervals: 1.08-2.02), and population-based studies (odds ratios: 1.60; 95% confidence intervals: 1.16-2.20).

Conclusions:

Collectively, finding from the current study indicated that GSTT1 null polymorphism may be susceptible on childhood acute leukemia among Chinese.

Trisenox induces cytotoxicity through phosphorylation of mitogen-activated protein kinase molecules in acute leukemia cells

Trisenox (TX) has been used successfully for the treatment of acute promyelocytic leukemia (APL) patients. TX-induced cytotoxicity in APL cells remains poorly understood. In this study, we investigated the molecular mechanism of TX cytotoxicity using APL cell lines. We assessed TX toxicity by quantitatively measuring lactate dehydrogenase levels. Inhibition of cell cycle progression was assessed by confocal microscopy of Ki-67 expression. Apoptosis was evaluated by Western blot analysis of apoptotic proteins expression, immunocytochemistry, and confocal imaging of annexin V and propidium iodide. Mitogen-activated protein kinase (MAPK) signaling cascade was analyzed by Western blot analysis and inhibitor-based experiments with APL cells. We found that TX-induced cytotoxicity inhibited APL cell cycle progression. TX also induced significant (P < 0.05) changes in the expression levels of apoptotic molecules and activated the phosphorylation of MAPK signaling pathways in APL cells. Understanding the mechanism of TX cytotoxicity would be helpful in the design of new APL drugs.

(-)-Epicatechin rescues the As2 O3 -induced HERG K+ channel deficiency possibly through upregulating transcription factor SP1 expression

(-)-Epicatechin (EPI) has beneficial effects on the cardiovascular disease. The human ether-a-go-go-related gene (HERG) potassium channel is crucial for repolarization of cardiac action potential. Dysfunction of the HERG channel can cause long QT syndrome type 2 (LQT2). Arsenic trioxide (As2 O3 ) has shown efficacy in the treatment of acute promyelocytic leukemia. However, As2 O3 can induce the deficiency of HERG channel and cause LQT2. In this study, we examined whether EPI could rescue the As2 O3 -induced HERG channel deficiency. We found that 3 μM EPI obviously increased protein expression and current of HERG channel. EPI was able to recover the protein expression and current of HERG channel disrupted by As2 O3 . EPI was able to increase the expression of SP1 protein and recover the expression of SP1 protein disrupted by As2 O3 . In addition, EPI significantly shortened action potential duration prolonged by As2 O3 . Our data suggest that EPI rescues As2 O3 -induced HERG channel deficiency through upregulating SP1 expression.

Distinct Cytokine and Chemokine Profiles in Autism Spectrum Disorders

Previous studies have shown that immunological factors are involved in the pathogenesis of autism spectrum disorders (ASDs). However, this research has been conducted almost exclusively in Western contexts, and only a handful of studies on immune measures have been conducted in Asian populations, such as Chinese populations. The present study examined whether immunological abnormalities are associated with cognitive deficits and problem behaviors in Chinese children with ASD and whether these children show different immunological profiles. Thirteen typically developing (TD) children and 22 children with ASD, aged 6–17 years, participated voluntarily in the study. Executive functions and short-term memory were measured using neuropsychological tests, and behavioral measures were assessed using parent ratings. The children were also assessed on immunological measures, specifically, the levels of cytokines and chemokines in the blood serum. Children with ASD showed greater deficits in cognitive functions, as well as altered levels of immunological measures, including CCL2, CCL5, and CXCL9 levels, compared to TD children, and the cognitive functions and associated behavioral deficits of children with ASD were significantly associated with different immunological measures. The children were further sub-classified into ASD with only autistic features (ASD-only) or ASD comorbid with attention deficit hyperactivity disorder (ASD + ADHD). The comorbidity results showed that there were no differences between the two groups of ASD children in any of the cognitive or behavioral measures. However, the results pertaining to immunological measures showed that the children with ASD-only and ASD + ADHD exhibited distinct cytokine and chemokine profiles and that abnormal immunologic function was associated with cognitive functions and inattention/hyperactivity symptoms. These results support the notion that altered immune functions may play a role in the selective cognitive and behavioral symptoms of ASD.

Population pharmacokinetics and pharmacodynamics of busulfan with GSTA1 polymorphisms in patients undergoing allogeneic hematopoietic stem cell transplantation

AIM

A population pharmacokinetic (PPK) analysis was conducted to describe the influence of GSTA1 polymorphisms on intravenous busulfan in adults undergoing allogeneic hematopoietic stem cell transplantation.

PATIENTS & METHODS

A PPK model was developed from 36 patients by a one-compartment model with first-order elimination.

RESULTS

The typical value of clearance and volume of distribution were 11.0 l/h and 42.4 l, respectively. Clearance decreased by 15% and area under the concentration-time curves (AUCs) increased with GSTA1 variants compared with wild-type (both p < 0.05). Subtherapeutic AUCs were seen only in wild-type patients.

CONCLUSION

To our knowledge, this is the first PPK study to suggest that GSTA1 polymorphisms in adults are associated with busulfan PK.

Interaction between GSTT1 and GSTP1 allele variants as a risk modulating-factor for autism spectrum disorders

We investigated the role of glutathione S-transferase (GST) genes in Autism Spectrum Disorder (ASD). We used data from 111 pairs of age- and sex-matched ASD cases and typically developing (TD) controls between 2-8 years of age from Jamaica to investigate the role of GST pi 1 (GSTP1), GST theta 1 (GSTT1), and GST mu 1 (GSTM1) polymorphisms in susceptibility to ASD. In univariable conditional logistic regression models we did not observe significant associations between ASD status and GSTT1, GSTM1, or GSTP1 genotype (all P > 0.15). However, in multivariable conditional logistic regression models, we identified a significant interaction between GSTP1 and GSTT1 in relation to ASD. Specifically, in children heterozygous for the GSTP1 Ile105Val polymorphism, the odds of ASD was significantly higher in those with the null GSTT1 genotype than those with the other genotypes [Matched Odds Ratio (MOR) = 2.97, 95% CI (1.09, 8.01), P = 0.03]. Replication in other populations is warranted.

Glutathione-S-transferase polymorphism and acute lymphoblastic leukemia (ALL) in north Indian children: a case-control study and meta-analysis

Various studies on association of glutathione S-transferase (GST) polymorphisms and childhood acute lymphoblastic leukemia (ALL) have yielded conflicting results. We examined this association among north Indian children and conducted an updated meta-analysis to overcome sample size-related limitations. GSTM1, GSTP1 and GSTT1 genotypes in 100 children with ALL and 300 healthy controls were compared. GSTT1 null mutation (odds ratio (OR) 2.54, 95% confidence interval (CI) 1.50-4.32) and GSTP1 homozygous mutation (OR 3.13, 95%CI 1.48-6.59) were found to increase the risk of childhood ALL, while GSTM1 did not alter the risk. Meta-analysis included 22, 10 and 20 studies examining the association of childhood ALL with GSTM1, GSTP1 and GSTT1 genotypes, respectively. Only GSTM1 genotype (OR 1.29, 95%CI 1.10-1.62) was associated with increased risk in the overall analysis. However, both GSTM1 (OR 1.54, 95%CI 1.12-2.10) and GSTT1 (OR 1.63, 95%CI 1.32-1.99) null genotypes were associated with increased risk in Asian subjects. The risk of developing childhood ALL was not associated with GSTP1 genotype.

Effect of interaction of glutathione S-transferases (T1 and M1) on the hematologic and cytogenetic responses in chronic myeloid leukemia patients treated with imatinib

The glutathione S-transferases (GSTs) are phase II xenobiotic metabolizing enzymes known to be involved in the detoxification of carcinogens and anticancer drugs. Individual genetic variation linked to inherited polymorphisms of GSTT1 and GSTM1 leading to a complete loss of enzyme activity could expose subjects to develop cancer or to induce drug resistance. Indeed, despite the impressive results obtained with the imatinib, some patients with chronic myeloid leukemia (CML) fail to achieve the expected results or develop resistance. The present study aimed to examine the impact of GSTT1 and GSTM1 polymorphisms on the response to imatinib in patients with CML. Multiplex polymerase chain reaction was used to detect the genotypes of GSTT1 and GSTM1 in 60 CML patients. We found that side effects were more frequent in patients carrying GSTT1 null when compared to GSTT1 present carriers (31 vs. 16.6 %; χ (2) = 6.2; p = 0.013). The loss of hematologic response was statistically greater in patients carrying the combined genotype GSTT1 present/GSTM1 present (26.3 %) when compared to GSTT1 null/GSTM1 present (12.8 %), GSTT1 present/GSTM1 null (8.3 %) and GSTT1 null/GSTM1 null (0 %), (χ (2) = 18.85; p < 0.001). The complete cytogenetic response was higher in patients harboring the GSTT1 null/GSTM1 null (75 %) compared with GSTT1 null/GSTM1 present (55.6 %), GSTT1 present/GSTM1 null (50 %) and GSTT1 present/GSTM1 present (47.8). On the other hand, the frequency of none cytogenetic responders was more common in patients carrying GSTT1 present/GSTM1 present (34.8 %) when compared to other genotype combinations (χ (2) = 20.99; p = 0.05). Moreover, the GSTT1 present/GSTM1 present appeared to be associated with a final dose of 600 or 800 mg of imatinib, but not significantly. Based on these findings, we find that the interaction between GSTT1 and GSTM1 seems to influence treatment outcome in patients with CML. Therefore, further investigations are required to confirm these results, for better genotype-phenotype correlation.

Toxicogenetic profile and cancer risk in Lebanese

An increasing number of genetic polymorphisms in drug-metabolizing enzymes (DME) were identified among different ethnic groups. Some of these polymorphisms are associated with an increased cancer risk, while others remain equivocal. However, there is sufficient evidence that these associations become significant in populations overexposed to environmental carcinogens. Hence, genetic differences in expression activity of both Phase I and Phase II enzymes may affect cancer risk in exposed populations. In Lebanon, there has been a marked rise in reported cancer incidence since the 1990s. There are also indicators of exposure to unusually high levels of environmental pollutants and carcinogens in the country. This review considers this high cancer incidence by exploring a potential gene-environment model based on available DME polymorphism prevalence, and their impact on bladder, colorectal, prostate, breast, and lung cancer in the Lebanese population. The examined DME include glutathione S-transferases (GST), N-acetyltransferases (NAT), and cytochromes P-450 (CYP). Data suggest that these DME influence bladder cancer risk in the Lebanese population. Evidence indicates that identification of a gene-environment interaction model may help in defining future research priorities and preventive cancer control strategies in this country, particularly for breast and lung cancer.

GSTT1 genetic polymorphism and susceptibility to childhood acute lymphoblastic leukemia: a meta-analysis

Glutathione S-transferase T1 (GSTT1) genetic polymorphism has been considered as a risk factor for developing malignant diseases including acute lymphoblastic leukemia; however, the results from previous studies are inconsistent. We performed a meta-analysis of 16 published studies to investigate the association between GSTT1 null variant and risk of acute lymphoblastic leukemia in childhood. Between-study heterogeneity was assessed using the I (2) statistic method. Odds ratios (ORs) with corresponding 95 % confidence intervals (95 %CI) were pooled to assess the association. Those 16 studies were from 14 publications and included a total of 2,424 cases and 3,447 controls. Meta-analysis of a total of 16 studies showed that GSTT1 null variant was significantly associated with risk of childhood acute lymphoblastic leukemia (fixed-effect OR = 1.22, 95 %CI 1.07-1.39, P = 0.003, I (2) = 35 %). Subgroup analysis showed that GSTT1 null variant was significantly associated with risk of childhood acute lymphoblastic leukemia in Asians (fixed-effect OR = 1.47, 95 %CI 1.16-1.85, P = 0.001, I (2) = 0 %). However, there was no obvious association in both Caucasians (random-effect OR = 1.07, 95 %CI 0.83-1.38, P = 0.59, I (2) = 53 %) and Africans (random-effect OR = 0.99, 95 %CI 0.31-3.10, P = 0.98, I (2) = 72 %). Therefore, the GSTT1 null variant is significantly associated with susceptibility to childhood acute lymphoblastic leukemia in Asians.

GSTM1 and GSTT1 null polymorphisms and childhood acute leukemia risk: evidence from 26 case-control studies

Several molecular epidemiological studies have been conducted to examine the association between glutathione S-transferase mu-1 (GSTM1) and glutathione S-transferase theta-1 (GSTT1) null polymorphisms and childhood acute leukemia; however, the conclusions remain controversial. We performed an extensive meta-analysis on 26 published case-control studies with a total of 3252 cases and 5024 controls. Crude odds ratios (ORs) with 95% confidence interval were used to assess the strength of association between childhood acute leukemia risk and polymorphisms of GSTM1 and GSTT1. With respect to GSTM1 polymorphism, significantly increased risk of childhood acute leukemia was observed in the overall analysis (OR = 1.30; 95%CI, 1.11-1.51). Furthermore, a stratification analysis showed that the risk of GSTM1 polymorphism are associated with childhood acute leukemia in group of Asians (OR = 1.94; 95%CI, 1.53-2.46), Blacks (OR = 1.76; 95%CI, 1.07-2.91), ALL (OR = 1.33; 95%CI, 1.13-1.58), '< 100 cases and <100 controls' (OR = 1.79; 95%CI, 1.21-2.64), '≥ 100 cases and ≥ 100 controls' (OR = 1.25; 95%CI, 1.02-1.52), and population-based control source (OR = 1.40; 95%CI, 1.15-1.69). With respect to GSTT1 polymorphism, significant association with childhood acute leukemia risk was only found in subgroup of Asian. This meta-analysis supports that GSTM1 null polymorphism is capable of causing childhood acute leukemia susceptibility.

The association of glutathione S-transferase gene mutations (including GSTT1 and GSTM1) with the prognostic factors and relapse in acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. It accounts for one fourth of all childhood cancers and approximately 75% of all childhood leukemias. Some prognostic factors determine the outcome of therapy [e.g. age, sex, initial white blood cell count (WBC), etc.]; however, it is believed that other mechanisms such as glutathione S-transferase (GST) gene mutation, the expression of lung resistance protein (LRP), and multidrug resistance-associated protein (MRP) also plays a role in treatment failure. In this study, GST gene mutations including GSTM1 and GSTT1 were evaluated in patients with leukemia. Thirty newly diagnosed ALL patients younger than 15 years of age participated in the present study. Bone marrow aspiration and biopsy were evaluated for immune phenotyping and DNA was extracted for GST genotyping. All data plus sex, age, initial WBC count, central nervous system (CNS) or testicular involvement, immune phenotype, and outcome (relapse or not) were analyzed statistically. Genotyping showed that 46% were double null, 50% were M1 null and 93.3% were T1 null for GST mutations. There was no statistically significant relationship between GSTT1 and GSTM1 mutations, or between double null status, prognostic factors and relapse (P > .05). So, although the results of GST mutations were consistent, it seems that these mutations are not statistically significant.

Glutathione S-transferase homozygous deletions and relapse in childhood acute lymphoblastic leukemia: a novel study design in a large Italian AIEOP cohort

Aim: In the AIEOP-BFM 2000 trial, 15% of pediatric patients treated according to risk-adapted polychemotherapeutic regimens relapsed. The present study aimed to investigate the influence of GST-M1 and GST-T1 deletions on clinical outcome of children with acute lymphoblastic leukemia treated according to the AIEOP-BFM ALL 2000 study protocol. Materials & methods: A novel-design, two-phase study was applied to select a subsample of 614 children to be genotyped for the deletions of GST genes. Cumulative incidence of relapse was then estimated by weighted Kaplan–Meier analysis, and the Cox model was applied to evaluate the effect of GST-M1 and GST-T1 isoenzyme deletions on relapse. Results: No overall effect was found, but the GST-M1 deletion was associated with better clinical outcome within prednisone poor-responder patients (hazard ratio [HR]: 0.45; 95% CI: 0.23–0.91; p = 0.026), whereas the GST-T1 deletion was associated with worse outcome in the standard-risk group (HR: 4.62; 95% CI: 1.04–20.6; p = 0.045) and within prednisone good responders (HR: 1.62; 95% CI: 1.02–2.58; p = 0.041). Conclusion: Our results show that GST-M1 and GST-T1 homozygous deletions have opposite correlation with relapse, the former being protective and the latter unfavourable in specific subsets of acute lymphoblastic leukemia patients.

Original submitted 1 August 2012; Revision submitted 27 September 2012

Glutathione transferases, regulators of cellular metabolism and physiology

BACKGROUND

The cytosolic glutathione transferases (GSTs) comprise a super family of proteins that can be categorized into multiple classes with a mixture of highly specific and overlapping functions.

SCOPE OF REVIEW

The review covers the genetics, structure and function of the human cytosolic GSTs with particular attention to their emerging roles in cellular metabolism.

MAJOR CONCLUSIONS

All the catalytically active GSTs contribute to the glutathione conjugation or glutathione dependant-biotransformation of xenobiotics and many catalyze glutathione peroxidase or thiol transferase reactions. GSTs also catalyze glutathione dependent isomerization reactions required for the synthesis of several prostaglandins and steroid hormones and the catabolism of tyrosine. An increasing body of work has implicated several GSTs in the regulation of cell signaling pathways mediated by stress-activated kinases like Jun N-terminal kinase. In addition, some members of the cytosolic GST family have been shown to form ion channels in intracellular membranes and to modulate ryanodine receptor Ca(2+) channels in skeletal and cardiac muscle.

GENERAL SIGNIFICANCE

In addition to their well established roles in the conjugation and biotransformation of xenobiotics, GSTs have emerged as significant regulators of pathways determining cell proliferation and survival and as regulators of ryanodine receptors that are essential for muscle function. This article is part of a Special Issue entitled Cellular functions of glutathione.

Development of multiplex PCR method for the analysis of glutathione s-transferase polymorphism

BACKGROUND

Busulfan is a key compound in myeloablative chemotherapy before hematopoietic stem-cell transplantation in children. Genetic polymorphisms of glutathione S-transferase (GST), which is involved in the metabolism of busulfan, have been implicated in interindividual variability in busulfan pharmacokinetics. Development of a rapid and simplified method for polygenic analysis of GST may facilitate large pharmacogenetic studies and clinical application of individualized busulfan dose adjustment. We previously introduced an effective PCR method for analyzing multiple genes using a small amount of DNA, termed 'TotalPlex amplification'.

OBJECTIVE

The aim of this study was to extend the application of the TotalPlex method to the specific GST gene families (A1, P1, M1, and T1) that are related to busulfan metabolism, and thereby facilitate pharmacogenetic analysis of GST polymorphisms.

METHODS

Seven genetic polymorphisms (GSTA1 promoter -52G>A, -69C>T, -567T>G, and -631T>G; GSTP1 313A>G; GSTM1 deletion; and GSTT1 deletion) were analyzed by multiplex PCR and genotyping, and the genotyping results from TotalPlex were verified with those from uniplex PCR.

RESULTS

Using five pairs of specific bulging-specific primers, seven specific gene fragments were successfully amplified by multiplex amplification coupled to a multiplexed bead array detection system, with a smaller amount of DNA and a shorter process time than is needed for the conventional approach. The genotypes of seven loci from 30 different genomic DNA samples derived using the multiplex system were consistent with the results of standard genotyping methods.

CONCLUSION

Our multiplex system provides a fast, inexpensive, and accurate method of detecting multiple GST polymorphisms (GSTA1, GSTP1, GSTM1, and GSTT1).

Gene dose effects of GSTM1, GSTT1 and GSTP1 polymorphisms on outcome in childhood acute lymphoblastic leukemia

Children with acute lymphoblastic leukemia (ALL) react very differently to chemotherapy. One explanation for this is inherited genetic variation. The glutathione S-transferase (GST) enzymes inactivate a number of chemotherapeutic drugs administered in childhood ALL therapy. Two multiplexing methods were applied for genotyping the GSTM1 and GSTT1 genes (distinguishing between 0, 1, or 2 gene copies) and the GSTP1 313 A>G polymorphism, simultaneously. A total of 263 childhood ALL patients were genotyped. No gene dose effect on outcome was demonstrated with either GST polymorphisms. Grouping of GSTM1 and GSTT1 into poor (0 or 1 gene copy)-and good metabolizers (at least 2 gene copies)-showed that the poor metabolizers had a trend toward a better outcome (event-free survival =91.8%) compared with the good metabolizers (event-free survival =83.2%). Similarly, in the adjusted analysis the good metabolizers demonstrated a 2.2-fold higher risk trend of experiencing an event (resistant disease or relapse) compared with the poor metabolizers (P=0.066; hazard ratio =2.248; 95% confidence interval, 0.948-5.327). In conclusion, our results suggest that the combined gene dose of GSTM1 and GSTT1 may influence outcome in childhood ALL.

Managing acute promyelocytic leukemia without conventional chemotherapy: is it possible?

The introduction of all-trans retinoic acid in 1985 combined with anthracycline-based chemotherapy has revolutionized the prognosis of acute promyelocytic leukemia (APL) with current complete response rates of more than 90% and cure rates of approximately 80%. The subsequent advent of arsenic trioxide in 1994 marked an additional milestone in APL treatment and has inspired the design of rationally targeted, chemotherapy-free front-line treatment regimens without compromising the excellent outcome achieved by anthracycline-containing protocols. APL is, therefore, a unique subtype of acute myeloid leukemia potentially curable with targeted therapies without any exposure to conventional DNA-damaging chemotherapy. Cure rates of APL can be further increased by implementing management strategies to reduce early hemorrhagic deaths, which remain the major cause of treatment failure with the current therapy.

Dual functions of histone-lysine N-methyltransferase Setdb1 protein at promyelocytic leukemia-nuclear body (PML-NB): maintaining PML-NB structure and regulating the expression of its associated genes

Setdb1/Eset is a histone H3 lysine 9 (H3K9)-specific methyltransferase that associates with various transcription factors to regulate gene expression via chromatin remodeling. Here, we report that Setdb1 associates with promyelocytic leukemia (Pml) protein from the early stage of mouse development and is a constitutive member of promyelocytic leukemia (PML)-nuclear bodies (PML-NBs) that have been linked to many cellular processes such as apoptosis, DNA damage responses, and transcriptional regulation. Arsenic treatment, which induces Pml degradation, caused Setdb1 signals to disappear. Setdb1 knockdown resulted in dismantlement of PML-NBs. Immunoprecipitation results demonstrated physical interactions between Setdb1 and Pml. Chromatin immunoprecipitation revealed that, within the frame of PML-NBs, Setdb1 binds the promoter of Id2 and suppresses its expression through installing H3K9 methylation. Our findings suggest that Setdb1 performs dual, but inseparable, functions at PML-NBs to maintain the structural integrity of PML-NBs and to control PML-NB-associated genes transcriptionally.

As4S4 targets RING-type E3 ligase c-CBL to induce degradation of BCR-ABL in chronic myelogenous leukemia

Arsenic, a curative agent for acute promyelocytic leukemia, induces cell apoptosis and degradation of BCR-ABL in chronic myelogenous leukemia (CML). We demonstrated that ubiquitination and degradation of BCR-ABL was mediated by c-CBL, a RING-type E3 ligase that was also shown to be involved in ubiquitination for many other receptor/protein tyrosine kinases. Our data showed that c-CBL protein was considerably up-regulated by arsenic sulfide (As(4)S(4)). Interestingly, arsenic directly bound the RING finger domain of c-CBL to inhibit its self-ubiquitination/degradation without interfering with the enhancement of ubiquitination and subsequent proteolysis of its substrate BCR-ABL. Degradation of BCR-ABL due to c-CBL induction as a result of arsenic treatment was also observed in vivo in CML mice. These findings provide insight into the molecular mechanisms of arsenic and further support its therapeutic applications in CML in combination with tyrosine kinase inhibitors and potentially also in other malignancies involving aberrant receptor/protein tyrosine kinase signaling.

Nonnegative principal component analysis for cancer molecular pattern discovery

As a well-established feature selection algorithm, principal component analysis (PCA) is often combined with the state-of-the-art classification algorithms to identify cancer molecular patterns in microarray data. However, the algorithm's global feature selection mechanism prevents it from effectively capturing the latent data structures in the high-dimensional data. In this study, we investigate the benefit of adding nonnegative constraints on PCA and develop a nonnegative principal component analysis algorithm (NPCA) to overcome the global nature of PCA. A novel classification algorithm NPCA-SVM is proposed for microarray data pattern discovery. We report strong classification results from the NPCA-SVM algorithm on five benchmark microarray data sets by direct comparison with other related algorithms. We have also proved mathematically and interpreted biologically that microarray data will inevitably encounter overfitting for an SVM/PCA-SVM learning machine under a Gaussian kernel. In addition, we demonstrate that nonnegative principal component analysis can be used to capture meaningful biomarkers effectively.