Glutathione S-transferase P1 Gene Research Articles

A meta-analysis of the association of glutathione S-transferase P1 gene polymorphism with the susceptibility of breast cancer

Glutathione S-transferase P1 (GSTP1) is one of the important mutant sites for the cancer risk at present. The conclusions of the published reports on the relationship between GSTP1 A/G gene polymorphism and the risk of breast cancer are still debated. This meta-analysis was performed to evaluate the association between GSTP1 and the risk of breast cancer. The association reports were identified from PubMed and Cochrane Library, and eligible studies were included and synthesized using meta-analysis method. 35 investigations were included into this meta-analysis for the association of GSTP1 A/G gene polymorphism and breast cancer susceptibility, consisting of 40,347 subjects (18,665 patients with breast cancer and 21,682 controls). The association between GSTP1 A/G gene polymorphism and breast cancer risk was not found for overall population, Caucasians and Africans. Interestingly, the GSTP1 A/G gene polymorphism was associated with the susceptibility of breast cancer in Asians (G allele: OR = 1.10, 95 % CI: 1.04-1.17, P = 0.001; GG genotype: OR = 1.36, 95 % CI: 1.14-1.62, P = 0.0008; AA genotype: OR = 0.92, 95 % CI: 0.85-0.98, P = 0.02). Furthermore, the GSTP1 A/G gene polymorphism was associated with the susceptibility of breast cancer for the analysis of the controls from hospital. In conclusion, GSTP1 A/G gene polymorphism is associated with the breast cancer susceptibility in Asians. However, more studies on the relationship between GSTP1 A/G gene polymorphism and the risk of breast cancer should be performed in further.

Glutathione S-transferase P1 Ile105Val Polymorphism and Oral Cancer Risk: A Meta-Analysis

Objective The glutathione S-transferase P1 (GSTP1) gene has been suggested to play an important role in the pathogenesis of oral cancer. However, the results have been inconsistent. In this study, we performed a meta-analysis to clarify the association of GSTP1 Ile105Val polymorphisms with oral cancer risk.Methods Published literature from PubMed and EMBASE were retrieved. Pooled odds ratio (OR) with 95% confidence interval (CI) was calculated using fixed- or random-effects model.Results 13 studies (1803 oral cancer cases and 2998 controls) for GSTP1 Ile105Val polymorphism were included in the meta-analysis. The results indicated that there was no significant association between GSTP1 Ile105Val polymorphism and oral cancer in the overall population (OR=1.30, 95%CI=0.92-1.38, I2=48.0%, p for heterogeneity=0.027). Further subgroup analysis by ethnicity suggested that GSTP1 Ile105Val polymorphism was significantly associated with oral cancer only in East Asians (OR=1.64, 95%CI=1.16-2.31, I2=0.0%, p for heterogeneity=0.525), but not in Caucasians (OR=1.16, 95%CI=0.73-1.82, I2=7.5%, p for heterogeneity=0.299), Africans (OR=1.10, 95%CI=0.37-3.28), South Asians (OR=1.20, 95%CI=0.69-2.08, I2=74.3%, p for heterogeneity=0.021) and mixed population (OR=0.91, 95%CI=0.70-1.20, I2=39.7%, p for heterogeneity=0.174).Conclusions The present meta-analysis has limited evidence to support the association of GSTP1 Ile105Val polymorphism with HCC risk in the overall population. However, GSTP1 Ile105Val polymorphism might be associated with risk of oral cancer in East Asians.

Association of glutathione S-transferase P1 gene polymorphism with the histological types of lung cancer: a meta-analysis

The conclusions of the published reports on the relationship between glutathione S-transferase P1 (GSTP1) A/G gene polymorphism and the histological types of lung cancer are still debated. GSTP1 is one of the important mutant sites reported at present. This meta-analysis was performed to evaluate the association between GSTP1 and histological types of lung cancer. The association investigations were identified from PubMed and Cochrane Library, and eligible studies were included and synthesized using meta-analysis method. Seventeen reports were included into this meta-analysis for the association of GSTP1 A/G gene polymorphism and histological types of lung cancer. The G allele and GG genotype were not associated with the susceptibility of risk of squamous cell carcinomas, adenocarcinomas, small cell carcinoma, non-small cell carcinoma or large cell carcinoma. However, in the sub-group analysis, there was an association between G allele/GG genotype with the risk of squamous cell carcinomas in East-Asians and GG genotype was associated with the risk of small cell carcinoma in Caucasians. In conclusion, GSTP1 A/G gene polymorphism is not associated with the susceptibility of squamous cell carcinomas, adenocarcinomas, small cell carcinoma, non-small cell carcinoma or large cell carcinoma.

Association of A313g Glutathione S-Transferase P1 (GSTP1) Inborn Polymorphism with Susceptibility to De Novo MDS

AbstractAbstract 1445Models for the pathogenesis of myelodysplastic syndromes (MDS) imply the role of individual genetic variations in genes involved in detoxification mechanisms. GSTP1 enzyme plays a key role in detoxification of a variety of electrophilic compounds, such as benzo [a]-pyrene and other polycyclic aromatic hydrocarbons (PAHs), chemotherapy drugs and products of oxidative stress. GSTP1 acts through a common mechanism of conjugating reactive oxygen species (ROS) with glutathione, enabling their detoxification and elimination and thus defending tissues against DNA damage. The corresponding gene is subject to a single-nucleotide polymorphism (A313G) leading to abolished enzyme activity. Thus, individuals homozygous for the variant G allele (G/G) have a lower conjugating activity than individuals homozygous for the wild type A allele (A/A), while heterozygotes (A/G) display intermediate activity. The aim of the present study was to evaluate whether the GSTP1 polymorphism influences susceptibility to MDS and/or promote specific chromosomal aberrations.We conducted a case-control study in 310 de novo MDS patients and 370 unrelated healthy controls using both a conventional PCR-RFLP assay and a novel Real-Time PCR genotyping method using hybridization probe technology. The GSTP1 gene status was also evaluated in relation to patients' characteristics and chromosomal abnormalities.Comparison of the genotype distribution between controls and MDS cases revealed a significantly higher frequency of the variant genotypes (heterozygotes A/A and homozygotes G/G) among MDS patients, as compared to controls (p<0.0001, χ2=31.167, df=2). The most marked statistical difference between MDS patients and controls was observed between the wild-type (A/A) and the homozygous variant genotype (G/G), since subjects carrying the G/G variant genotype showed a 4.1-fold increased risk of MDS prevalence than subjects carrying the wild-type A/A genotype (p=0.000, χ2=30.5, d.f.=1, OR=4.098, 95%CI=[2.433–6.897]). Allele frequencies distribution analysis between patients and controls, showed that MDS patients exhibited a 1.9-fold increased risk of carrying at least one variant G allele, as compared to the controls (p<0.0001, d.f.=1, OR =1.9, 95%CI=[1.48–2.34]). There was no association between the GSTP1 polymorphism and gender or any specific cytogenetic subgroup, while stratification of patients according to age showed a differential GSTP1 genotype distribution (p=0.007). Our results, derived from the larger series of primary MDS cases tested for the GSTP1 genetic background, reveal an increased incidence of the GSTP1 variant genotypes among MDS patients, providing evidence for a potential pathogenetic role of the GSTP1 polymorphism on de novo MDS risk. Disclosures:No relevant conflicts of interest to declare.

Association of glutathione S-transferase P1 gene polymorphism with the susceptibility of lung cancer

The conclusions of the published reports on the relationship between glutathione S-transferase P1 (GSTP1) gene polymorphism and the risk of lung cancer are still debated. GSTP1 is one of the important mutant sites reported at present. This meta-analysis was performed to evaluate the association between GSTP1 and the risk of lung cancer. The association investigations were identified from PubMed and Cochrane Library, and eligible studies were included and synthesized using meta-analysis method. Forty-four reports were included into this meta-analysis for the association of GSTP1 A/G gene polymorphism and lung cancer susceptibility, consisting of 12,363 patients with lung cancer and 13,948 controls. The association between GSTPI G allele and lung cancer risk was found in this meta-analysis (OR 1.08, 95 % CI 1.02-1.15, P = 0.01). However, the GG genotype and AA genotype were not associated with the susceptibility of lung cancer. Furthermore, there was no association between GSTP1 A/G gene polymorphism and the risk of lung cancer in Caucasians, and East-Asians. In conclusion, GSTP1 G allele is associated with the lung cancer susceptibility. However, more studies on the relationship between GSTP1 A/G gene polymorphism and the risk of lung cancer should be performed in the future.

Glutathione S-transferase P1 gene polymorphism and bladder cancer susceptibility: an updated analysis

Studies investigating the association between glutathione S-transferase P1 (GSTP1) gene polymorphism and bladder cancer (BC) risk have reported conflicting results. In order to clarify the effect of GSTP1 polymorphism on the BC susceptibility, we conducted an updated system review of published epidemiology studies to provide more precise evidence. We performed a systematic search of PubMed, EMBASE, and China National Knowledge Infrastructure (CNKI). 20 studies with 4,428 BC cases and 5,457 controls were identified. The combined analyses based on all studies showed that there was a significant difference in the genotype distribution in GSTP1(A313G) polymorphism between BC cases and controls not only in Asians (GG vs. AA + AG, OR = 1.59, 95 % CI = 1.01-2.51) but also in Caucasians (GG vs. AA + AG, OR = 1.51, 95 % CI = 1.11-2.06). Upon stratification for smoking status, we observed no statistically significant difference in genotype distribution of GSTP1 in ever-smokers. Combination of the high-risk genotypes (GSTM1 null + GSTT1 null + GSTP1 313 A/G or G/G) demonstrated further increase in the BC risk (OR = 6.64, 95 %CI = 3.63-12.16). This meta-analysis suggests that GSTP1 313 G/G polymorphism is a strong predisposing risk factor for BC.

Effect of gene GSTP1 silencing via shRNA transfection on androgen independent prostate cancer cell line Du145

To design short hairpin RNA (shRNA) interference sequence to silence glutathione S-transferase P1 (GSTP1) gene of androgen independent prostate cancer cell line DU145, and to explore its effect on proliferation and sensitivity to chemotherapeutics. The target sequence was picked up to form the shRNA, and the 3 shRNA expression vectors were shRNA255, shRNA554 and shRNA593. The DNA template was cloned to plasmid pGPU6/GFP/Neo. The shRNA was identified by enzyme digesting and gene sequencing. The screening experiment was done to pick up the shRNA expression vector with the highest transfection ratio and best gene silencing results. DU145 cells were divided into a blank plasmid group and a shRNA transfected group. According to the chemotherapeutics the DU145 cells were divided into a fluorouracil (FU) group and a paclitaxel (PA) group, and the 2 groups were subdivided into 4 subsets according to the chemotherapeutic concentrations (FU: 30, 60, 120, and 240 μg/mL; PA: 0.2, 2, 10, and 20 μg/mL), meanwhile a blank control group was included respectively. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate the proliferation after the transfection. MTT and terminal de-oxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay were used to detect the inhibition effect of different concentrations of 5-FU or PA on the proliferation and induction of apoptosis of DU145. The transfection ratio of the 3 shRNA expression vectors (shRNA255, shRNA554, and shRNA593) was (63.30±1.04)%, (76.20±0.68)%, and (72.70±0.33)%, and the transfection ratio of shRNA554 was the highest. there was significant difference among the above 3 shRNA expression vectors (P<0.01). After the transfection, the mRNA was 128.31±2.50, 43.24±4.30 and 85.62±6.30, the GSTP1 protein was 163.92±12.40, 65.38±9.30 and 114.25±16.70. After the transfection of shRNA554, the mRNA and protein of GSTP1 were the lowest level. there was significant difference among the above 3 shRNA expression vector (P<0.01). MTT analysis showed that before the transfection, the survival ratio of cells under different concentrations of FU (30, 60, 120, and 240 μg/mL) was (95.60±2.11)%, (90.20±0.86)%, (83.10±3.12)% and (74.60±1.32)%; however after the transfection, the survival ratio of cells was (91.30±1.43)%, (84.60±2.13)%, (73.20±1.52)%, and (65.5±0.942)%. TUNEL assay showed that before the transfection, the apoptosis ratio of cells under different concentrations of FU (30, 60, 120, and 240 μg/mL) was (5.50±0.88)%, (10.20±1.64)%, (15.20±2.39)%, and (25.10±2.59)%; however after the transfection, the apoptosis ratio of cells was (10.8±0.62)%, (15.7±1.32)%, (20.4±1.89)%, and (34.9±2.54)%. After the transfection, the cell survival ratio decreased under the same concentration of FU, and the apoptosis ratio increased, with statistical significance (both P<0.01). MTT analysis showed that before the transfection, the survival ratio of cells under different concentrations of PA (0.2, 2, 10, and 20 μg/mL) was (98.50±2.34)%, (95.20±1.32)%, (89.40±0.68)%, and (82.70±1.73)%; after the transfection the survival ratio of cells was (94.20±0.78)%, (86.50±2.13)%, (78.70±1.34)%, and (70.10±0.76)%. TUNEL assay showed that before the transfection, the apoptosis ratio of cells under different concentrations of PA (0.2, 2, 10, and 20 μg/mL) were (2.40±1.07)%, (5.20±1.33)%, (10.50±2.41)%, (20.70±1.92)%; after the transfection the apoptosis ratio of cells was (5.46±2.13)%, (13.80±1.24)%, (21.20±2.39)%, and (29.20±2.21)%. After the transfection, the cell survival ratio decreased under the same PA concentration, and the apoptosis ratio increased, with statistical significance (both P<0.01). gene GSTP1 silence via shRNA transfection to androgen independent prostate cancer cell line DU145 can inhibit its proliferation in time dependent manner, and induce apoptosis and raise its sensitivity to chemotherapeutics.

Glutathione S-transferase P1 gene Ile105Val polymorphism might be associated with lung cancer risk in the Chinese Han population

Genetic variations in glutathione S-transferase P1 (GSTP1) gene have been suggested to be involved in the development of cancer. However, the results from the studies regarding the association between GSTP1 Ile105Val polymorphism and lung cancer risk in the Chinese population have been inconsistent. Thus, we conducted a meta-analysis to investigate the association. Published literature from PubMed, Chinese Biomedical Literature Database, Chinese Wanfang Data, and Chinese National Knowledge Infrastructure databases were searched for eligible publications. Pooled odds ratios (ORs) with 95 % confidence intervals (CIs) were calculated using random or fixed effect model. Ten studies (1,506 cases/1,714 controls) were included in the meta-analysis. The results suggested that GSTP1 Ile105Val polymorphism was marginally associated with lung cancer risk in the Chinese Han population under a multiplicative model (G vs. A, odds ratio (OR) = 1.22, 95 % confidence interval = 1.02-1.46), under a homogeneous codominant model (GG vs. AA, OR = 1.67, 95 % CI = 1.14-2.45), under a heterogeneous codominant model (GA vs. AA, OR = 1.15, 95 % CI = 0.98-1.35), under a dominant model (GG + GA vs. AA, OR = 1.21, 95 % CI = 1.04-1.39), and under a recessive model (GG vs. GA + AA, OR = 1.59, 95 % CI = 1.09-2.31), respectively. Moreover, after adjusted for age, gender, and smoking status, the significant association under dominant model remained (OR = 1.27, 95 % CI = 1.07-1.51). This meta-analysis suggested that there might be an association between GSTP1 Ile105Val polymorphism and lung cancer in the Chinese Han population.

Constitutive expression of an antioxidant enzyme, glutathione S-transferase P1, during differentiation of human intestinal Caco-2 cells

In this study, we investigated the molecular mechanism of the constitutive expression of an antioxidant enzyme, glutathione S-transferase (GST), during differentiation of human intestinal epithelial Caco-2 cells. We observed that the class π GST isozyme (GST P1) expression correlated with the increased expression of caudal-related homeodomain protein 2 (CDX2), a member of the mammalian homeobox family of transcription factors. In addition, transfection of Caco-2 cells with the human CDX2 cDNA resulted in enhanced expression of the GST P1 gene and protein. Chromatin immunoprecipitation assay demonstrated that CDX2 binds to the GST P1 promoter containing the putative consensus CDX-binding element, TTTAC, located at −247 upstream from the established site for transcription initiation. Using the dsDNA pull-down assay, it was revealed that CDX2 recognized and bound to the putative consensus CDX-binding element within the human GST P1 promoter region and that the amount of the CDX2 bound to the putative consensus CDX-binding element increased during Caco-2 cell differentiation. Furthermore, we demonstrated that CDX2 formed the transcriptional complex with Sp1 and bound to the putative consensus CDX-binding element within the human GST P1 promoter region. These data suggest that CDX2 binds to the human GST P1 promoter via complex formation with Sp1 and controls the constitutive expression of GST P1 during Caco-2 cell differentiation.

Association of GSTP1 gene (I105V) polymorphism with acute leukaemia

Glutathione S-transferase P1 (GSTP1) enzyme plays a key role in biotransformation and bioactivation of certain environmental pollutants such as benzo[a]pyrene-7, 8-diol-9, 10-epoxide (BPDE) and other diol epoxides of polycyclic aromatic hydrocarbons (Hengstler et al. 1998) and catalyses detoxification of base propanols that arise from DNA oxidation thus offering cellular protection against oxidative stress. GSTP1 gene belongs to the pi class gene family, located on chromosome 11q13 (Autrup 2000). It comprises of seven exons (Morrow et al. 1989; Bora et al. 1997) and codes for cytosolic GST enzyme (Fryer et al. 1986). The first polymorphism identified is an A–G polymorphism at nucleotide 313 in exon 5 of GSTP1 gene which leads to an amino acid substitution of isoleucine (IE) by valine (val) at 105 amino acid position (Ile105Val). This substitution results in three GSTP1 genotypes: they are isoleucine/isoleucine (Ile/Ile) homozygous wildtype, isoleucine/valine (Ile/Val) heterozygote and valine/valine (Val/Val) homozygous variant.GSTP1 codon 105 polymorphism might play an important role in leukaemiogenesis, as it potentially alters protein function, diminishing its detoxification ability for certain mutagens and carcinogens, which could result in increased DNA damage and mutation, and a greater risk of developing cancer. Biochemical studies indicated that GSTP1 Val105 allele has a lower thermal stability than GSTP1 Ile105 allele (Zimniak et al. 1994; Johanson et al. 1998), and Val homozygotes had a lower conjugating activity than Ile homozygotes, with heterozygotes displaying intermediate activity (Watson et al. 1998). Individuals with at least one Val allele at codon 105 of GSTP1 enzyme might have an underlying predisposition to cancer when exposed to environmentally derived

Genetic Variation in Glutathione S-Transferase Genes and Risk of Nonfatal Cerebral Stroke in Patients Suffering from Essential Hypertension

Oxidative stress resulting from an increased amount of reactive oxygen species and an imbalance between oxidants and antioxidants has been implicated in pathogenesis of cerebral stroke. The purpose of this study was to investigate the relationship between common polymorphisms of glutathione S-transferase M1, T1, and P1 genes and risk of stroke in hypertensive individuals. A total of 667 unrelated Russian individuals with hypertension, including 306 hypertensives who suffered from cerebral stroke and 361 hypertensives who did not have cerebrovascular accidents, were recruited for the study. The deletion polymorphisms of GSTM1 and GSTT1 genes and polymorphism Ile105Val of the GSTP1 gene were genotyped by a multiplex polymerase chain reaction and restriction analyses, respectively. No differences in GSTM1 and GSTP1 genotype distributions between the cases and controls have been observed. The null GSTT1 genotype was found to be associated with increased risk of cerebral stroke after Bonferroni correction and adjusting for confounding variables such as gender, blood pressure, body mass index, and antihypertensive medication use (odds ratio 1.51 95% CI 1.09-2.07, P = 0.01). The present study was the first to show the association of null genotype of the GSTT1 gene with increased risk of cerebral stroke.

Abstract 789: GSTP1 expression is regulated by MycN and is a marker of poor outcome in childhood neuroblastoma

Abstract In childhood neuroblastoma, amplification of the transcription factor MycN is associated with poor outcome and a multidrug resistant phenotype. We have previously shown that MycN regulates the expression of several ATP-binding cassette (ABC) transporter genes, and that these genes represent powerful prognostic markers in neuroblastoma (1,2,3). Although these transporters are able to efflux a wide range of cytotoxic drugs, they do not confer resistance to several important cytotoxic agents used to treat neuroblastoma, including cisplatin and cyclophosphamide, hence we explored the prognostic significance and transcriptional regulation of the phase II detoxifying enzyme, glutathione S-transferase P1 (GSTP1). Using quantitative real-time PCR, GSTP1 gene expression was assessed in a retrospective cohort of 51 patients, and subsequently in a cohort of 207 prospectively accrued primary neuroblastomas. These data, and GSTP1 expression data from an independent microarray study of 251 neuroblastoma samples, were correlated with established prognostic indicators and disease outcome. High levels of GSTP1 were associated with decreased event-free and overall survival in all three cohorts. Multivariate analyses, including age at diagnosis, tumor stage and MYCN amplification status, were conducted on the two larger cohorts and demonstrated independent prognostic significance of GSTP1 expression levels. We also explored the regulation of GSTP1 by MycN using chromatin immunoprecipitation (ChIP) and luciferase reporter assays in neuroblastoma cell lines and found that GSTP1 is a direct transcriptional target of MycN. We conclude that N-Myc regulates multiple components of drug metabolism and efflux pathways, including GSTP1 and transporters of the ABC superfamily. The regulation of these key multidrug resistance mechanisms may have particular significance for malignancies with amplification of Myc family genes. 1) J Biol Chem, 285:19532-19543, 2010 2) J Natl Cancer Institute, 103:1236-51, 2011 4) Nat Rev Cancer, 10:147-156, 2010 Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 789. doi:1538-7445.AM2012-789

Genetic Polymorphisms of Glutathione S‐Transferase M1, T1, and P1, and the Assessment of Oxidative Damage in Infertile Men With Varicoceles From Northwestern China

Our objective was to investigate the genetic polymorphisms of the glutathione S-transferase M1, T1, and P1 genes (GSTM1, GSTT1, and GSTP1) and to assess the oxidative damage in infertile men with varicoceles from northwestern China. A total of 65 infertile men with varicoceles and 30 controls were included in the study. Multiplex polymerase chain reaction and polymerase chain reaction-restriction fragment length polymorphism analyses were used to identify the genotypes. Sperm DNA damage was assessed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL). The levels of 8-hydroxy-2'-deoxyguanosine (8-OH-dG) were measured by high-performance liquid chromatography with electrochemical detection. The activities of malondialdehyde (MDA) and nitric oxide (NO), and the total antioxidant capacity (TAC) were detected by spectroscopic analysis, and sperm characteristics were measured using computer-assisted semen analysis. The frequencies of the GSTM1, GSTT1, and GSTP1 genotypes were not significantly different between the control and patient groups (P > .05). The percentage of TUNEL-positive sperm and the levels of 8-OH-dG, MDA, and NO were higher but the sperm concentration and motility and the TAC were lower in the patients with the GSTM1, GSTT1, and GSTM1/T1 null genotypes than those in the patients with the GSTM1, GSTT1, and GSTM1/T1 present genotypes (P < .05). However, no significant differences were observed between the GSTP1 A/A and A/G+G/G genotypes (P > .05). Our results suggest that the GSTM1 and GSTT1 null genotypes may predispose sperm to increased oxidative damage in infertile men with varicoceles; however, GSTP1 allelic variation was not significantly different between the patient and control groups in this study.

N-Myc Regulates Expression of the Detoxifying Enzyme Glutathione Transferase GSTP1, a Marker of Poor Outcome in Neuroblastoma

Amplification of the transcription factor MYCN is associated with poor outcome and a multidrug-resistant phenotype in neuroblastoma. N-Myc regulates the expression of several ATP-binding cassette (ABC) transporter genes, thus affecting global drug efflux. Because these transporters do not confer resistance to several important cytotoxic agents used to treat neuroblastoma, we explored the prognostic significance and transcriptional regulation of the phase II detoxifying enzyme, glutathione S-transferase P1 (GSTP1). Using quantitative real-time PCR, GSTP1 gene expression was assessed in a retrospective cohort of 51 patients and subsequently in a cohort of 207 prospectively accrued primary neuroblastomas. These data along with GSTP1 expression data from an independent microarray study of 251 neuroblastoma samples were correlated with established prognostic indicators and disease outcome. High levels of GSTP1 were associated with decreased event-free and overall survival in all three cohorts. Multivariable analyses, including age at diagnosis, tumor stage, and MYCN amplification status, were conducted on the two larger cohorts, independently showing the prognostic significance of GSTP1 expression levels in this setting. Mechanistic investigations revealed that GSTP1 is a direct transcriptional target of N-Myc in neuroblastoma cells. Together, our findings reveal that N-Myc regulates GSTP1 along with ABC transporters that act to control drug metabolism and efflux. Furthermore, they imply that strategies to jointly alter these key multidrug resistance mechanisms may have therapeutic implications to manage neuroblastomas and other malignancies driven by amplified Myc family genes.

Electrochemical DNA biosensor for detecting cancer biomarker related to glutathione S-transferase P1 (GSTP1) hypermethylation in real samples

An electrochemical genosensor for the detection of hypermethylation of the glutathione S-transferase P1 (GSTP1) gene, a specific marker of prostate cancer, was reported. This new sensor was used in combination with a single-use carbon graphite working electrode and differential pulse voltammetry, with the results of sample analysis based on the guanine oxidation signals obtained at +1.0V before and after hybridization between probe and synthetic target or denatured PCR samples. The detected DNA hybridization was also characterized by electrochemical impedance spectroscopy with potassium ferri/ferrocyanide as a redox probe. The protocol consisted of 2 different modes: (i) capture probes selective for methylation-specific and unmethylated GSTP1 sequences were immobilized onto the sensor directly, and hybridization was formed on the electrode surface; (ii) probe/target or probe/noncomplementary target couples were mixed in solution phase, and the transducer was modified through simple adsorption. The limit of detection (S/N=3) was calculated as 2.92pmol of target sequence in a 100-μl reaction volume. The optimum analytical detection parameters for the biosensor, as well as its future prospects, were also presented.

Role of Glutathione-S-Transferase P1 Hypermethylation in Molecular Detection of Prostate Cancer

The aim of this study was to evaluate the diagnostic potential of the quantification of glutathione-S-transferase P1 (GSTP1) gene hypermethylation in molecular detection of prostate cancer in tissue biopsies. One hundred fourteen male patients were enrolled in the study; 44 patients with histopathologically confirmed prostate adenocarcinoma, 20 patients with variable degrees of prostate intraepithelial neoplasia, and 50 with benign prostatic hyperplasia, who served as a control group. Real-time quantitative methylation-specific polymerase chain reaction was used for assessment of methylation of the promoter region of the GSTP1 gene. Methylation of the GSTP1 promotor was detected in 24% of patients with benign prostatic hyperplasia, 60% of patients with prostate intraepithelial neoplasia, and in 86.3% of prostate adenocarcinoma patients. A statistically significant difference in the GSTP1/MYOD1 (myogenic differentiation 1gene) methylation ratios among the three groups was observed (p=0.0001). At the cutoff value of 9, GSTP1/MYOD1 methylation ratios showed sensitivity in the detection of prostate adenocarcinoma of 71.8% and specificity of 96%. Methylation of the GSTP1 promotor is a common molecular alteration in prostate cancer that may be a useful adjunct to serum screening tests and digital rectal examination findings and the use of quantitative real-time methylation-specific polymerase chain reaction is a promising technique that often distinguishes malignant from nonmalignant prostate disease.

Analysis of glutathione S-transferase genes polymorphisms and the risk of schizophrenia in a sample of Iranian population

Glutathione S-transferases (GSTs) are major intracellular antioxidants, which, impaired in their function, are involved in the progress of schizophrenia (SCZ). The aim of this case-control study was to investigate the association between the polymorphism of glutathione S-transferases M1 (GSTM1), T1 (GSTT1), the glutathione S-transferase P1 gene (GSTP1) and SCZ. We isolated genomic DNA from peripheral blood of 93 individuals with SCZ and 99 healthy control subjects' genotypes analyzing them for GSTM1, GSTT1 and GSTP1 using polymerase chain reaction. The analysis of the gene-gene interaction between GSTs indicated that the magnitude of the association was greater for the combined AG/GSTT1 & GSTM1 genotypes (OR=2.51; 95% CI: 1.13-5.63, P=0.02). The AG and combined AG+GG genotypes of GSTP1 increased the risk of SCZ (OR=1.83; 95% CI: 0.94-3.75 and OR=1.71; 95% CI: 0.92-3.19, respectively). The genotypes of GSTT/NULL, NULL/GSTM and NULL/NULL increased the risk of SCZ (OR=2.05; 95% CI: 0.9-4.74; OR=2.0; 95% CI: 1.68-2.31; and OR=1.8; 95% CI: 0.57-2.46, respectively). The present study supports previous data that suggest that impairment in the function of GSTs genes may increase the risk of SCZ.

Reversible epigenetic fingerprint-mediated glutathione- S-transferase P1 gene silencing in human leukemia cell lines

Glutathione- S-transferase P1 (GSTP1) gene is commonly silenced by CpG island promoter hypermethylation in prostate, breast, and liver cancers. However, mechanisms leading to GSTP1 repression by promoter hypermethylation in leukemia and its relationship with pathological alterations of the chromatin structure remain poorly understood. A panel of leukemia cell lines was analyzed for their GSTP1 expression, revealing cell lines with high, moderate or no detectable GSTP1 expression. Bisulfite sequencing, methylation-specific PCR and combined bisulfite restriction analysis revealed that GSTP1 promoter was completely methylated in transcriptionally inactive RAJI and MEG-01 cell lines. In contrast, cell lines expressing GSTP1 exhibited an unmethylated and transcriptionally active promoter. Furthermore, histone marks and effector proteins associated with transcriptional activity were detected by chromatin immunoprecipitation in the GSTP1 expressing hypomethylated K-562 cell line. However, repressive chromatin marks and the recruitment of silencing protein complexes were found in the non-expressing hypermethylated RAJI and MEG-01 cell lines. Finally, we provide evidence that treatment of RAJI and MEG-01 cells with the DNA demethylating agent, 5-aza-2′-deoxycytidine, resulted in GSTP1 promoter demethylation, drastic changes of histone modifications and promoter associated proteins and GSTP1 gene activation. In contrast, treatments with HDAC inhibitors failed to demethylate and reactivate the GSTP1 gene. Our study extends the knowledge on leukemia-specific epigenetic alterations of GSTP1 gene. Furthermore, we are showing the correlation of DNA methylation and histone modifications with the positive/negative GSTP1 transcriptional expression state. Finally, these data support the concept of the dominance of DNA methylation over HDAC inhibitor-sensitive histone deacetylation in gene silencing.

Promoter methylation profile of GSTP1 and RASSF1A in benign hyperplasia and metastatic prostate cancer patients in a Kashmiri population

Promoter hypermethylation is a marginal approach to inactivating tumor suppressor genes in cancer. DNA hypermethylation is a well-recognized epigenetic malfunction observed in several malignancies, most predominantly in prostate cancer. Aberrant DNA methylation patterns are considered to be the earliest somatic genome changes in prostate cancer. The function of promoter hypermethylation in malignant transformation of the prostate has been widely studied, from its presence in benign hyperplasia (BHP) to development and to the advanced stages of tumor formation. In the present study, we examined the promoter hypermethylation status of the glutathione S-transferase P1 (GSTP1) and RASSF1A genes in 45 BHP samples, 50proven prostate tumor samples and 80normal samples. Hypermethylated GSTP1 was found in 29/50(58.0%) prostate carcinoma cases and 12/45(26.6%) BHP cases. The RASSF1A gene was methylated in 17/50(34.0%) prostate cancer samples and 7/45(15.5%) BHP samples. On the basis of these findings, we propose that the epigenetic regulation of the GSTP1 and RASSF1A genes through promoter hypermethylation may play a crucial role in the progression of prostate cancer, and has probable involvement in BHP.

Gene promoter hypermethylation in leukoplakia of the oral mucosa

Gene promoter hypermethylation in leukoplakia of the oral mucosa Mingli Liu1, Lei Feng2, Ximing Tang3, Shanchun Guo41Department of Physics, Tufts University School of Medicine, Boston, Massachussetts; 2Department of Thoracic/Head and Neck Medical Oncology, 3Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas; 4Sylvester Cancer Center, University of Miami School of Medicine, Florida, USAAbstract: To examine whether aberrant DNA methylation in the promoter region might occur earlier in tumorigenesis, particularly in premalignant lesions, we examined biopsies from 111 participants in a chemoprevention trial aimed at reversal of oral leukoplakia, using methylation-specific polymerase chain reaction for the promoter regions of the tumor suppressor gene CDKN2A (p16), the putative metastasis suppressor gene for death-associated protein kinase (DAP-K), the DNA repair gene O6-methyguanine-DNA-methyltransferase (MGMT), and the detoxification gene glutathione S-transferase p1(GSTP1). p16 promoter hypermethylation was detected in 21 of 82 (25.6%), DAP-K hypermethylation in 28 of 87 (32.2%), and MGMT hypermethylation in 32 of 106 (30.2%) oral leukoplakia lesions analyzed. No aberrant methylation was found at the GSTP1 gene in 110 lesions examined. Among 68 biopsies analyzed for all three genes (p16, DAP-K, MGMT), 17 biopsies were detected with an abnormal methylation pattern at only one gene, 15 at two genes, and 8 at all three genes. Among clinical characteristics and their correlation with methylation, only alcohol consumption was correlated with DAP-K methylation (P = 0.027), while MGMT methylation was more frequent in females (P = 0.003) and nonsmokers (P = 0.0005). A significant correlation was found between p16 and DAP-K hypermethylation; p16 promoter was methylated in 14 (56%) of 25 lesions with DAP-K methylation, and only 5 (11.1%) of 45 DAP-K methylation-negative lesions (P = 0.0001). DAP-K aberrant methylation was also significantly correlated with MGMT methylation (16 of 31 in MGMT methylation-positive lesions versus 12 of 52 MGMT methylation-negative lesions, P = 0.0016). Our results suggest that epigenetic mechanisms of inactivation, such as aberrant methylation of p16, DAP-K, and MGMT genes, occur early in head and neck tumorigenesis, and might play a role in the progression of these lesions.Keywords: p16, DAP-K, MGMT, GSTP1 genes, methylation, leukoplakia