Gene Summary

Gene:GSTT2; glutathione S-transferase theta 2 (gene/pseudogene)
Summary:The protein encoded by this gene, glutathione S-transferase (GST) theta 2 (GSTT2), is a member of a superfamily of proteins that catalyze the conjugation of reduced glutathione to a variety of electrophilic and hydrophobic compounds. Human GSTs can be divided into five main classes: alpha, mu, pi, theta, and zeta. The theta class includes GSTT1, GSTT2, and GSTT2B. GSTT2 and GSTT2B are nearly identical to each other, and share 55% amino acid identity with GSTT1. All three genes may play a role in human carcinogenesis. The GSTT2 gene is a pseudogene in some populations. [provided by RefSeq, Sep 2015]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:glutathione S-transferase theta-2
Source:NCBIAccessed: 13 March, 2017


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 13 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Glutathione Transferase
  • Mexico
  • Base Sequence
  • Chromosome 22
  • Adenocarcinoma
  • Haplotypes
  • Random Allocation
  • Pregnancy
  • Precancerous Conditions
  • Case-Control Studies
  • Cytochrome P-450 CYP1A1
  • Newborns
  • Smoking
  • Childhood Cancer
  • Polymerase Chain Reaction
  • Sequence Deletion
  • Non-Small Cell Lung Cancer
  • Genetics, Population
  • Cancer DNA
  • Cancer Gene Expression Regulation
  • Polymorphism
  • Adolescents
  • Esophageal Cancer
  • Genotype
  • South Africa
  • Promoter Regions
  • Linkage Disequilibrium
  • Risk Factors
  • Biomarkers, Tumor
  • Oligonucleotide Array Sequence Analysis
  • Messenger RNA
  • Colorectal Cancer
  • Carcinogens
  • DNA, Complementary
  • Single Nucleotide Polymorphism
  • Transcription
  • Lung Cancer
  • Genetic Predisposition
  • DNA
Tag cloud generated 13 March, 2017 using data from PubMed, MeSH and CancerIndex

Latest Publications: GSTT2 (cancer-related)

Serizawa M, Kusuhara M, Zangiacomi V, et al.
Identification of metabolic signatures associated with erlotinib resistance of non-small cell lung cancer cells.
Anticancer Res. 2014; 34(6):2779-87 [PubMed] Related Publications
BACKGROUND/AIM: The acquisition of resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) remains a major challenge in lung cancer medicine. We sought to identify biomarkers for the early detection of resistance to TKIs.
MATERIALS AND METHODS: Capillary electrophoresis time-of-flight mass spectrometry analysis was performed to identify the metabolic signatures associated with erlotinib resistance in erlotinib-resistant PC-9ER NSCLC cells established from the EGFR-mutant NSCLC cell line PC-9.
RESULTS: PC-9ER cells showed metabolic signatures indicative of enhanced glutamine metabolism. Copy number gains in v-myc avian myelocytomatosis viral oncogene homolog (MYC), glutathione-S-transferase theta 2 (GSTT2), gamma-glutamyltransferase 1 (GGT1), and GGT5 were also detected, suggesting that amplification of these genes confers glutamine addiction in PC-9ER cells.
CONCLUSION: Enhanced glutamine metabolism may be a surrogate marker that can be used to predict the likelihood of patients to respond to EGFR-TKIs.

Matejcic M, Li D, Prescott NJ, et al.
Association of a deletion of GSTT2B with an altered risk of oesophageal squamous cell carcinoma in a South African population: a case-control study.
PLoS One. 2011; 6(12):e29366 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Polymorphisms in the Glutathione S-transferase genes are associated with altered risks in many cancers, but their role in oesophageal cancer is unclear. Recently a 37-kb deletion polymorphism of GSTT2B that reduces expression of GSTT2 has been described. We evaluated the influence of the GSTT1 and GSTT2B deletion polymorphisms, and the GSTP1 Ile105Val polymorphism (rs1695) on susceptibility to oesophageal squamous cell carcinoma (OSCC) in the Black and Mixed Ancestry populations of South Africa.
METHODS AND RESULTS: The GSTT1, GSTT2B and GSTP1 variants were genotyped in 562 OSCC cases and 907 controls, and tested for association with OSCC and for interaction with smoking and alcohol consumption. Linkage disequilibrium (LD) between the deletions at GSTT1 and GSTT2B was determined, and the haplotypes tested for association with OSCC. Neither the GSTT1 deletion nor the GSTP1 Ile105Val polymorphism was associated with OSCC risk in the Black or Mixed Ancestry populations. The GSTT2B deletion was not associated with OSCC risk in the Black population, but was associated with reduced risk of OSCC in the Mixed Ancestry population (OR=0.71; 95% CI 0.57-0.90, p=0.004). Case-only analysis showed no interaction between the GST polymorphisms and smoking or alcohol consumption. LD between the neighboring GSTT1 and GSTT2B deletions was low in both populations (r(2)(Black)=0.04; r(2)(MxA)=0.07), thus these deletions should be assessed independently for effects on disease risk.
CONCLUSIONS: Although there was no association between the GSTT1 deletion polymorphism or the GSTP1 Ile105Val polymorphism with OSCC, our results suggest that the presence of the recently described GSTT2B deletion may have a protective effect on the risk of OSCC in the Mixed Ancestry South African population. This is the first report of the contribution of the GSTT2B deletion to cancer risk.

Lam TK, Rotunno M, Lubin JH, et al.
Dietary quercetin, quercetin-gene interaction, metabolic gene expression in lung tissue and lung cancer risk.
Carcinogenesis. 2010; 31(4):634-42 [PubMed] Free Access to Full Article Related Publications
Epidemiological and mechanistic evidence on the association of quercetin-rich food intake with lung cancer risk and carcinogenesis are inconclusive. We investigated the role of dietary quercetin and the interaction between quercetin and P450 and glutathione S-transferase (GST) polymorphisms on lung cancer risk in 1822 incident lung cancer cases and 1991 frequency-matched controls from the Environment And Genetics in Lung cancer Etiology study. In non-tumor lung tissue from 38 adenocarcinoma patients, we assessed the correlation between quercetin intake and messenger RNA expression of the same P450 and GST metabolic genes. Multivariate odds ratios (ORs) and 95% confidence intervals (CIs) for sex-specific quintiles of intake were calculated using unconditional logistic regression adjusting for putative risk factors. Frequent intake of quercetin-rich foods was inversely associated with lung cancer risk (OR = 0.49; 95% CI: 0.37-0.67; P-trend < 0.001) and did not differ by P450 or GST genotypes, gender or histological subtypes. The association was stronger in subjects who smoked >20 cigarettes per day (OR = 0.35; 95% CI: 0.19-0.66; P-trend = 0.003). Based on a two-sample t-test, we compared gene expression and high versus low consumption of quercetin-rich foods and observed an overall upregulation of GSTM1, GSTM2, GSTT2, and GSTP1 as well as a downregulation of specific P450 genes (P-values < 0.05, adjusted for age and smoking status). In conclusion, we observed an inverse association of quercetin-rich food with lung cancer risk and identified a possible mechanism of quercetin-related changes in the expression of genes involved in the metabolism of tobacco carcinogens in humans. Our findings suggest an interplay between quercetin intake, tobacco smoking, and lung cancer risk. Further research on this relationship is warranted.

Dumontet C, Landi S, Reiman T, et al.
Genetic polymorphisms associated with outcome in multiple myeloma patients receiving high-dose melphalan.
Bone Marrow Transplant. 2010; 45(8):1316-24 [PubMed] Related Publications
High-dose melphalan (HDM) is an essential component in the treatment of patients with multiple myeloma (MM). Few data are available regarding genetic polymorphisms associated with patient outcome or toxicity in this setting. To identify such polymorphisms, we performed a retrospective analysis, genotyping single nucleotide polymorphisms (SNPs) with the arrayed primer extension (APEX) technology in 169 patients having received HDM for MM. We analyzed 209 SNPs in 95 genes involved in drug metabolism, DNA repair, cell cycle and apoptosis. SNPs in ABCB1, CYP3A4 and TP53BP2 were associated with response to VAD induction therapy (P<0.01). SNPs in ALDH2, GSTT2 and BRCA1 were associated with response to HDM (P<0.01). Polymorphisms in CYP1A1, RAD51 and PARP were associated with disease progression whereas polymorphisms in ALDH2 and CYP1A1 were correlated with OS. Polymorphisms in BRCA1, CDKN1A and XRCC1 were associated with the occurrence of severe mucositis after HDM. These results suggest that SNPs of genes involved in drug metabolism or DNA repair could be used to distinguish MM patient subgroups with different toxicity/efficacy profiles.

Miene C, Klenow S, Veeriah S, et al.
Impact of apple polyphenols on GSTT2 gene expression, subsequent protection of DNA and modulation of proliferation using LT97 human colon adenoma cells.
Mol Nutr Food Res. 2009; 53(10):1254-62 [PubMed] Related Publications
Apple extract (AE) enhances expression of glutathione S-transferases (e.g., GSTT2) in human colon cells (LT97). Therefore, aim of the present study was to identify functional consequences of GSTT2 induction by AE and to determine the relation of AE effects to isolated compounds. Polyphenol composition of AE was analyzed. LT97 cells were treated with AE or synthetic polyphenol mixture (SPM) under conditions that induced GSTT2, and challenged with GSTT2-2 substrate cumene hydroperoxide (CumOOH) to determine DNA damage using comet assay. Modulation of GSTT2 expression (real-time PCR) was reassessed, and the influence on cell proliferation and pro-oxidative potential of AE and SPM were assessed to understand additional mechanisms. Induction of GSTT2 by AE was accompanied by protection of LT97 cells from CumOOH-induced genotoxicity. Although SPM was unable to reflect AE-specific bioactivity related to GSTT2 modulation and anti-genotoxicity, inhibition of LT97 cell proliferation by SPM was comparable. Storage of AE caused changes in phenolic composition along with loss of activity regarding GSTT2 induction and amplified growth inhibition. At the applied concentrations, no H(2)O(2) formation was detectable with any of the substances. AE can protect against oxidatively induced DNA damage. Nevertheless, chemopreventive effects of AE strongly depend on the specific composition, which is modified by storage.

Zhao Y, Marotta M, Eichler EE, et al.
Linkage disequilibrium between two high-frequency deletion polymorphisms: implications for association studies involving the glutathione-S transferase (GST) genes.
PLoS Genet. 2009; 5(5):e1000472 [PubMed] Free Access to Full Article Related Publications
Copy number variations (CNVs) represent a large source of genetic variation in humans and have been increasingly studied for disease association. A deletion polymorphism of the gene encoding the cytosolic detoxification enzyme glutathione S-transferase theta 1 (GSTT1) has been extensively studied for cancer susceptibility (919 studies, from HuGE navigator, However, clear conclusions have not been reached. Since the GSTT1 gene is located within a genomic region of segmental duplications (SD), there may be a confounding effect from another, yet-uncharacterized CNV at the same locus. Here we describe a previously uncharacterized 38-kilo-base (kb) long deletion polymorphism of GSTT2B located within a 61-kb DNA inverted repeat. GSTT2B is a duplicated copy of GSTT2, the only paralogue of GSTT1 in humans. A newly developed PCR assay revealed that a microhomology-mediated breakpoint appears to be shared among individuals at high frequency. The GSTT2B deletion polymorphism was in strong linkage disequilibrium (LD) (D' = 0.841) with the neighboring GSTT1 deletion polymorphism in the Caucasian population. Alleles harboring a single deletion were significantly overrepresented (p = 2.22 x 10(-16)), suggesting a selection against alleles with both deletions. The deletion alleles are almost certainly the derived ones, because the GSTT2B-GSTT2-GSTT1 genes were strictly retained in chimpanzees. Extremely low GSTT2 mRNA expression was associated with the GSTT2B deletion, suggesting an influence of the deletion on the flanking region and loss of GSTT2 function. Genome-wide LD analysis between deletion polymorphisms further points to the uniqueness of two deletions, because strong LD between deletion polymorphisms might be very rare in humans. These results show a complex genomic organization and unexpected biological functions of CNVs within segmental duplications and emphasize the importance of detailed structural characterization for disease association studies.

Peng DF, Razvi M, Chen H, et al.
DNA hypermethylation regulates the expression of members of the Mu-class glutathione S-transferases and glutathione peroxidases in Barrett's adenocarcinoma.
Gut. 2009; 58(1):5-15 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The accumulation of reactive oxygen species and subsequent oxidative DNA damage underlie the development of Barrett's oesophagus (BO) and its progression to Barrett's dysplasia (BD) and adenocarcinoma (BAC).
METHODS: The promoter regions of 23 genes of the glutathione S-transferase (GST) and glutathione peroxidase (GPX) families were systematically analysed. Quantitative bisulfite pyrosequencing, real-time RT-PCR, western blot and immunohistochemical (IHC) analysis methods were utilised in this study.
RESULTS: 14 genes were identified that have CpG islands around their transcription start sites: GSTs (GSTM2-M5, GSTA4, GSTP1, GSTZ1, GSTT2, GSTO1 and GSTO2) and GPXs (GPX1, GPX3, GPX4 and GPX7). Analysis of an initial set of 20 primary samples demonstrated promoter DNA hypermethylation and mRNA downregulation of GPX3, GPX7, GSTM2, GSTM3 and GSTM5 in more than half of the BAC samples. Further analysis of 159 primary human samples (37 normal, 11 BO, 11 BD and 100 BACs) indicated frequent hypermethylation (>or=10% methylation) of GPX3 (62%), GPX7 (67%), GSTM2 (69.1%) and GSTM3 (15%) in BACs. A significant inverse correlation between DNA methylation and mRNA expression level was shown for GPX3 (p<0.001), GPX7 (p = 0.002), GSTM2 (p<0.001) and GSTM5 (p = 0.01). Treatment of oesophageal cancer cell lines with 5-aza-2'-deoxycytidine and trichostatin-A led to reversal of the methylation pattern and re-expression of these genes at the mRNA and protein levels. The IHC analysis of GPX3, GPX7 and GSTM2 on a tissue microarray that contained 75 BACs with normal squamous oesophageal samples demonstrated an absent to weak staining in tumours (52% for GPX3, 57% for GPX7 and 45% for GSTM2) and a moderate to strong immunostaining in normal samples.
CONCLUSION: Epigenetic inactivation of members of the glutathione pathway can be an important mechanism in Barrett's tumourigenesis.

Karami S, Boffetta P, Rothman N, et al.
Renal cell carcinoma, occupational pesticide exposure and modification by glutathione S-transferase polymorphisms.
Carcinogenesis. 2008; 29(8):1567-71 [PubMed] Free Access to Full Article Related Publications
This study investigated associations between occupational pesticide exposure and renal cell carcinoma (RCC) risk. To follow-up on a previous report by Buzio et al., we also considered whether this association could be modified by glutathione S-transferase M1 and T1 (GSTM1 and GSTT1) genotypes. About 1097 RCC cases and 1476 controls from Central and Eastern Europe were interviewed to collect data on lifetime occupational histories. Occupational information for jobs held for at least 12 months duration was coded for pesticide exposures and assessed for frequency and intensity of exposure. GSTM1 and GSTT1 gene deletions were analyzed using TaqMan assays. A significant increase in RCC risk was observed among subjects ever exposed to pesticides [odds ratio (OR): 1.60; 95% confidence interval (CI): 1.00-2.55]. After stratification by genotypes, increased risk was observed among exposed subjects with at least one GSTM1 active allele (OR: 4.00; 95% CI: 1.55-10.33) but not among exposed subjects with two GSTM1 inactive alleles compared with unexposed subjects with two inactive alleles (P-interaction: 0.04). Risk was highest among exposed subjects with both GSTM1 and GSTT1 active genotypes (OR: 6.47; 95% CI: 1.82-23.00; P-interaction: 0.02) compared with unexposed subjects with at least one GSTM1 or T1 inactive genotype. In the largest RCC case-control study with genotype information conducted to date, we observed that risk associated with pesticide exposure was exclusive to individuals with active GSTM1/T1 genotypes. These findings further support the hypothesis that glutathione S-transferase polymorphisms can modify RCC risk associated with occupational pesticide exposure.

Veeriah S, Miene C, Habermann N, et al.
Apple polyphenols modulate expression of selected genes related to toxicological defence and stress response in human colon adenoma cells.
Int J Cancer. 2008; 122(12):2647-55 [PubMed] Related Publications
Apples contain significant amounts of flavonoids that are potentially cancer risk reducing by acting antioxidative or antiproliferative and by favorably modulating gene expression. The purpose of this study was to investigate whether polyphenols from apples modulate expression of genes related to colon cancer prevention in preneoplastic cells derived from colon adenoma (LT97). For this, LT97 cells were treated with effective concentrations of apple extracts (AEs). RNA was isolated and used for synthesis and labeling of cDNA that was hybridized to cDNA-arrays. Gene expression studies were performed using a commercial cDNA-array from Superarray that contains a limited number of genes (96 genes) related to drug metabolism, and a custom-made cDNA microarray that contains a higher number of genes (300 genes, including some genes from Superarray) related to mechanisms of carcinogenesis or chemoprevention. Real-time PCR and enzyme activity assays were additionally performed to confirm selected array results. Treatment of cells with AE resulted in 30 and 46 genes expressed over cut-off values (>or=1.5- or

Wang S, Chanock S, Tang D, et al.
Assessment of interactions between PAH exposure and genetic polymorphisms on PAH-DNA adducts in African American, Dominican, and Caucasian mothers and newborns.
Cancer Epidemiol Biomarkers Prev. 2008; 17(2):405-13 [PubMed] Free Access to Full Article Related Publications
Polycyclic aromatic hydrocarbons (PAH) are widespread pollutants commonly found in air, food, and drinking water. Benzo[a]pyrene is a well-studied representative PAH found in air from fossil fuel combustion and a transplacental carcinogen experimentally. PAHs bind covalently to DNA to form DNA adducts, an indicator of DNA damage, and an informative biomarker of potential cancer risk. Associations between PAH-DNA adduct levels and both cancer risk and developmental deficits have been seen in previous experimental and epidemiologic studies. Several genes have been shown to play an important role in the metabolic activation or detoxification of PAHs, including the cytochrome P450 genes CYP1A1 and CYP1B1 and the glutathione S-transferase (GST) genes GSTM1, and GSTT2. Genetic variation in these genes could influence susceptibility to adverse effects of PAHs in polluted air. Here, we have explored interactions between prenatal PAH exposure and 17 polymorphisms in these genes (rs2198843, rs1456432, rs4646903, rs4646421, rs2606345, rs7495708, rs2472299, rs162549, rs1056837, rs1056836, rs162560, rs10012, rs2617266, rs2719, rs1622002, rs140194, and gene deletion GSTM1-02) and haplotypes on PAH-DNA adducts in cord blood of 547 newborns and in maternal blood of 806 mothers from three different self-described ethnic groups: African Americans, Dominicans, and Caucasians. PAHs were measured by personal air monitoring of mothers during pregnancy. Significant interactions (p < 0.05) were observed between certain genetic polymorphisms and CYP1A1 haplotype and PAHs in mothers and their newborns in the three ethnic groups. However, with our limited sample size, the current findings are suggestive only, warranting further study.

Zienolddiny S, Campa D, Lind H, et al.
A comprehensive analysis of phase I and phase II metabolism gene polymorphisms and risk of non-small cell lung cancer in smokers.
Carcinogenesis. 2008; 29(6):1164-9 [PubMed] Related Publications
Lung cancer is a leading cause of cancer mortality worldwide with smoking and occupational exposure to carcinogenic compounds as the major risk factors. Susceptibility to lung cancer is affected by existence of polymorphic genes controlling the levels of metabolic activation and detoxification of carcinogens. We have investigated 105 single nucleotide polymorphisms (SNPs) in 31 genes from the phase I and phase II metabolism genes and antioxidant defense genes for association with the risk of non-small cell lung cancer (NSCLC) in a Norwegian population-based study. Our results indicate that several SNPs in the phase I genes, CYP1B1, CYP2D6, CYP2E1 and CYP3A4, are associated with the risk of NSCLC. Moreover, significant associations with multiple SNPs in the phase II genes ALDH2, COMT, EPHX1, SOD2, NAT1, NAT2, GSTM3, GSTP1, GSTT2 and MPO were also found. We prioritized our findings by use of two different recently developed Bayesian statistical tools, employing conservative prior probabilities of association. When we corrected for multiple testing using these statistical tools, three novel associations of NSCLC risk with SNPs in the CYP1B1 (Arg48Gly), COMT (Val158Met) and GSTT2 (Met139Ile) genes were found noteworthy. However, only four of the previously reported associations with polymorphisms in the GSTP1 (Ala14Val), SOD2 (Val16Ala), EPHX1 (His139Arg) genes and the NAT1 fast acetylator phenotype remained significantly associated with lung cancer.

Jariwala U, Prescott J, Jia L, et al.
Identification of novel androgen receptor target genes in prostate cancer.
Mol Cancer. 2007; 6:39 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The androgen receptor (AR) plays critical roles in both androgen-dependent and castrate-resistant prostate cancer (PCa). However, little is known about AR target genes that mediate the receptor's roles in disease progression.
RESULTS: Using Chromatin Immunoprecipitation (ChIP) Display, we discovered 19 novel loci occupied by the AR in castrate resistant C4-2B PCa cells. Only four of the 19 AR-occupied regions were within 10-kb 5'-flanking regulatory sequences. Three were located up to 4-kb 3' of the nearest gene, eight were intragenic and four were in gene deserts. Whereas the AR occupied the same loci in C4-2B (castrate resistant) and LNCaP (androgen-dependent) PCa cells, differences between the two cell lines were observed in the response of nearby genes to androgens. Among the genes strongly stimulated by DHT in C4-2B cells--D-dopachrome tautomerase (DDT), Protein kinase C delta (PRKCD), Glutathione S- transferase theta 2 (GSTT2), Transient receptor potential cation channel subfamily V member 3 (TRPV3), and Pyrroline-5-carboxylate reductase 1 (PYCR1)--most were less strongly or hardly stimulated in LNCaP cells. Another AR target gene, ornithine aminotransferase (OAT), was AR-stimulated in a ligand-independent manner, since it was repressed by AR siRNA knockdown, but not stimulated by DHT. We also present evidence for in vivo AR-mediated regulation of several genes identified by ChIP Display. For example, PRKCD and PYCR1, which may contribute to PCa cell growth and survival, are expressed in PCa biopsies from primary tumors before and after ablation and in metastatic lesions in a manner consistent with AR-mediated stimulation.
CONCLUSION: AR genomic occupancy is similar between LNCaP and C4-2B cells and is not biased towards 5' gene flanking sequences. The AR transcriptionally regulates less than half the genes nearby AR-occupied regions, usually but not always, in a ligand-dependent manner. Most are stimulated and a few are repressed. In general, response is stronger in C4-2B compared to LNCaP cells. Some of the genes near AR-occupied regions appear to be regulated by the AR in vivo as evidenced by their expression levels in prostate cancer tumors of various stages. Several AR target genes discovered in the present study, for example PRKCD and PYCR1, may open avenues in PCa research and aid the development of new approaches for disease management.

Ragel BT, Couldwell WT, Gillespie DL, Jensen RL
Identification of hypoxia-induced genes in a malignant glioma cell line (U-251) by cDNA microarray analysis.
Neurosurg Rev. 2007; 30(3):181-7; discussion 187 [PubMed] Related Publications
Overcoming the metabolic restrictions of hypoxia may allow the progression of lower-grade tumors to glioblastoma multiforme. Our findings of up-regulation of HIF-1alpha and its downstream targets VEGF, GLUT-1, and CAIX in higher-grade gliomas support this hypothesis. We compared the gene expression profiles of the U-251 malignant glioma cell line under normoxic and hypoxic conditions to discover future research targets. U-251 cells were grown to 75% confluence and exposed to either normoxic or hypoxic conditions for 24 h. RNA was extracted, amplified, and hybridized to a cDNA microarray chip containing ~8,800 universal cellular genes. A threefold increase in mRNA expression was used as a threshold value for differential expression. Identified genes were divided into cell cycle control, stress response, and "newly connected" genes. Hybridization identified 11 hypoxia-induced genes: 1 involved with cell cycle control (CCNG2), 6 in stress response (IGFBP3, SLC2A3, GSTT2, FOS, DDIT3, AKR1C3), and 2 newly connected genes (Depp, AKAP4). One stress-related gene (AKR1C3) encodes for an enzyme that synthesizes progesterone. Of newly connected genes, the gene decidual protein induced by progesterone (Depp) showed the highest expression (4.2-fold increase). Possible future targeting for "hypoxic" glioma cells includes the targets for the AP-1 transcription factor complex (FOS), as well as blockade of the enzyme AKR1C3 with nonsteroidal anti-inflammatory drugs. Possible functions of the highly expressed gene Depp include tumor vascularization. Future studies will focus on the hypothesis that Depp is up-regulated in an autocrine fashion by the AKR1C3 enzyme in U-251 glioma cells under hypoxic conditions.

Jang SG, Kim IJ, Kang HC, et al.
GSTT2 promoter polymorphisms and colorectal cancer risk.
BMC Cancer. 2007; 7:16 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Glutathione S-transferases are a group of enzymes that participate in detoxification and defense mechanisms against toxic carcinogens and other compounds. These enzymes play an important role in human carcinogenesis. In the present study, we sought to determine whether GSTT2 promoter single nucleotide polymorphisms (SNPs) are associated with colorectal cancer risk.
METHODS: A total of 436 colorectal cancer patients and 568 healthy controls were genotyped for three GSTT2 promoter SNPs (-537G>A, -277T>C and -158G>A), using real-time TaqMan assay and direct sequencing. An electrophoretic mobility shift assay (EMSA) was performed to determine the effects of polymorphisms on protein binding to the GSTT2 promoter.
RESULTS: The -537A allele (-537G/A or A/A) was significantly associated with colorectal cancer risk (OR = 1.373, p = 0.025), while the -158A allele (-158G/A or A/A) was involved in protection against colorectal cancer (OR = 0.539, p = 0.032). Haplotype 2 (-537A, -277T, -158G) was significantly associated with colorectal cancer risk (OR = 1.386, p = 0.021), while haplotype 4 (-537G, -277C, -158A) protected against colorectal cancer (OR = 0.539, p = 0.032). EMSA data revealed lower promoter binding activity in the -537A allele than its -537G counterpart.
CONCLUSION: Our results collectively suggest that SNPs and haplotypes of the GSTT2 promoter region are associated with colorectal cancer risk in the Korean population.

Veeriah S, Kautenburger T, Habermann N, et al.
Apple flavonoids inhibit growth of HT29 human colon cancer cells and modulate expression of genes involved in the biotransformation of xenobiotics.
Mol Carcinog. 2006; 45(3):164-74 [PubMed] Related Publications
Flavonoids from fruits and vegetables probably reduce risks of diseases associated with oxidative stress, including cancer. Apples contain significant amounts of flavonoids with antioxidative potential. The objectives of this study were to investigate such compounds for properties associated with reduction of cancer risks. We report herein that apple flavonoids from an apple extract (AE) inhibit colon cancer cell growth and significantly modulate expression of genes related to xenobiotic metabolism. HT29 cells were treated with AE at concentrations delivering 5-50 microM of one of the major ingredients, phloridzin ("phloridzin-equivalents," Ph.E), to the cell culture medium, with a synthetic flavonoid mixture mimicking the composition of the AE or with 5-100 microM individual flavonoids. HT29 cell growth was inhibited by the complex extract and by the mixture. HT29 cells were treated with nontoxic doses of the AE (30 microM, Ph.E) and after 24 h total RNA was isolated to elucidate patterns of gene expression using a human cDNA-microarray (SuperArray) spotted with 96 genes of drug metabolism. Treatment with AE resulted in an upregulation of several genes (GSTP1, GSSTT2, MGST2, CYCP4F3, CHST5, CHST6, and CHST7) and downregulation of EPHX1, in comparison to the medium controls. The enhanced transcriptional activity of GSTP1 and GSTT2 genes was confirmed with real-time qRT-PCR. On the basis of the pattern of differential gene expression found here, we conclude that apple flavonoids modulate toxicological defense against colon cancer risk factors. In addition to the inhibition of tumor cell proliferation, this could be a mechanism of cancer risk reduction.

Landi S, Gemignani F, Moreno V, et al.
A comprehensive analysis of phase I and phase II metabolism gene polymorphisms and risk of colorectal cancer.
Pharmacogenet Genomics. 2005; 15(8):535-46 [PubMed] Related Publications
OBJECTIVES: Sporadic colorectal cancer (CRC) is considered a multifactorial disease where multiple exposures interact with the individual genetic background resulting in risk modulation. We performed an association study aimed to investigate the role of single nucleotide polymorphisms (SNPs) within genes of phase I (CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2D6, CYP2E1, CYP2C9, CYP2C19, CYP3A4, ADH2, EPHX1) and phase II of the xenobiotic metabolism (ALDH2, COMT, GSTA2, GSTA4, GSTM1, GSTM3, GSTP1, GSTT2, MTHFR, NAT1, NAT2, NQO1, MnSOD2, SULT1A1, TPMT).
METHODS: We genotyped 377 cases and 326 controls, by use of an oligonucleotide micro-array and the arrayed primer extension technique (APEX).
RESULTS: N-acetyl-transferase 1 'rapid' phenotype and CYP1A2 -164C>A carriers were associated with increased risk of CRC, confirming data reported in previous studies. Interestingly, homozygotes for allele 48G within CYP1B1, a variant with an increased activity towards several substrates including sex hormones, were at increased risk (OR=2.81, 95% CI 1.32-5.99). Moreover, CYP1A1 SNPs T461N and -1738A>C were associated with a reduced risk of cancer (OR=0.52; 95% CI 0.31-0.88 and OR=0.69, 95% CI 0.50-0.94 for carriers, respectively).
CONCLUSIONS: The present data suggest a role for CYP1B1 and CYP1A1 as new candidate genes in the etiology of CRC and confirm the carcinogenic role of aromatic amines metabolism for colorectum.

Efferth T, Volm M
Glutathione-related enzymes contribute to resistance of tumor cells and low toxicity in normal organs to artesunate.
In Vivo. 2005 Jan-Feb; 19(1):225-32 [PubMed] Related Publications
The anti-malarial artesunate (ART) also inhibits the growth of cancer cells. The active moiety is an endoperoxide bridge whose cleavage generates reactive oxygen species and free radicals. We analyzed whether glutathione-related enzymes contribute to tumor resistance to ART and to the low toxicity of ART towards normal organs. The microarray-based mRNA expression of dihydrodiol dehydrogenase, gamma-glutamylcysteine synthase (gamma-GCS), glutathione S-transferases GSTM4, GSTT2, GSTZ1, and microsomal glutathione S-transferase MGST3 showed significant relationships (p <0.05) to cellular response to ART in 55 cell lines of the National Cancer Institute, USA. A tendency for correlation (0.05

Pool-Zobel BL, Selvaraju V, Sauer J, et al.
Butyrate may enhance toxicological defence in primary, adenoma and tumor human colon cells by favourably modulating expression of glutathione S-transferases genes, an approach in nutrigenomics.
Carcinogenesis. 2005; 26(6):1064-76 [PubMed] Related Publications
Butyrate, formed by bacterial fermentation of plant foods, has been suggested to reduce colon cancer risks by suppressing the proliferation of tumor cells. In addition, butyrate has been shown to induce glutathione S-transferases (GSTs) in tumor cell lines, which may contribute to the detoxification of dietary carcinogens. We hypothesize that butyrate also affects biotransformation in non-transformed colon cells. Thus, we have investigated the gene expression of drug metabolism genes in primary human colon tissue, premalignant LT97 adenoma and HT29 tumor cells cultured in an appropriate medium+/-butyrate. A total of 96 drug metabolism genes (including 12 GSTs) spotted on cDNA macroarrays (Superarray; n = 3) were hybridized with biotin-labeled cDNA probes. To validate the expression detected with Superarray, samples of LT97 cells were also analyzed with high density microarrays (Affymetrix U133A), which include biotransformation genes that overlap with the set of genes represented on the Superarray. Relative expression levels were compared across colon samples and for each colon sample+/-butyrate. Compared with fresh tissue, 13 genes were downregulated in primary cells cultivated ex vivo, whereas 8 genes were upregulated. Several genes were less expressed in LT97 (40 genes) or in HT29 (41 and 17 genes, grown for 72 and 48 h, respectively) compared with primary colon tissue. Butyrate induced GSTP1, GSTM2, and GSTA4 in HT29 as previously confirmed by other methods (northern blot/qPCR). We detected an upregulation of GSTs (GSTA2, GSTT2) that are known to be involved in the defence against oxidative stress in primary cells upon incubation with butyrate. The changes in expression detected in LT97 by Superarray and Affymetrix were similar, confirming the validity of the results. We conclude that low GST expression levels were favourably altered by butyrate. An induction of the toxicological defence system possibly contributes to reported chemopreventive properties of butyrate, a product of dietary fibre fermentation in the gut.

Joseph T, Kusumakumary P, Chacko P, et al.
Genetic polymorphism of CYP1A1, CYP2D6, GSTM1 and GSTT1 and susceptibility to acute lymphoblastic leukaemia in Indian children.
Pediatr Blood Cancer. 2004; 43(5):560-7 [PubMed] Related Publications
BACKGROUND: Biotransformation plays a crucial role in carcinogen activity and many genetic polymorphisms in xenobiotic metabolising enzymes have been associated with an increased risk of cancer. Such polymorphisms can lead to considerable variation in the activities of these enzymes, which are crucial in carcinogen and drug metabolism. These variations could play a role in the risk of developing paediatric acute lymphoblastic leukaemia (ALL) by their varying action on environmental carcinogens.
PROCEDURE: The present study looked for two polymorphisms (m1 and m2) in the CYP1A1, CYP2D6*4 genes and deletions of the glutathione S-transferases (GSTM1 and GSTT1) in 118 paediatric ALL patients and 118 age matched control children. The polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) were used to study gene polymorphisms.
RESULTS: In children with ALL, CYP1A1 m1 polymorphism was evident in 42.4% of subjects and CYP1A1 m2 in 37.3%. These were significantly different from the results obtained for control children (20.3% for CYP1A1 m1 and 19.5% for m2). Subjects with CYP1A1 m1 homozygous variant had a sixfold risk and CYP1A1 m2 a fourfold risk. In contrast, CYP2D6*4 was more prevalent in the controls than in the cases. Subjects with GSTM1 deletions had increased risk of ALL (OR = 2.1, P = 0.009). The odds ratios for both CYP1A1 m1 and m2 homozygous polymorphisms being associated with childhood ALL was 5.67 (95% CI = 2.11-15.27). The odds ratios for both GSTM1 and GSTT1 deletions being associated with ALL was 2.78 (95% CI = 0.67-11.56).
CONCLUSIONS: These results suggest that genetic polymorphisms of xenobiotic metabolising enzymes appear to influence susceptibility to childhood ALL.

Zielińska E, Zubowska M, Bodalski J
Polymorphism within the glutathione S-transferase P1 gene is associated with increased susceptibility to childhood malignant diseases.
Pediatr Blood Cancer. 2004; 43(5):552-9 [PubMed] Related Publications
BACKGROUND: Glutathione S-transferases (GSTs) are involved in the metabolism of carcinogens and anticancer drugs. Functional polymorphisms exist in at least three genes that code for the GSTs, such as the GSTM1 and GSTT1 gene deletions or the A-G transition within the GSTP1 gene, which represents distinct GSTP1a and GSTP1b alleles. In the present case-control study, we aimed at estimation of the relationship between the GSTM1, GSTT1, and GSTP1 genotypes and the susceptibility to various types of childhood malignancies and the early relapses of diseases.
PROCEDURE: Using the polymerase chain reaction on the DNA extracted from peripheral blood leukocytes, we identified the GSTM1, GSTT1, and GSTP1 genotypes in 234 children at the initial stage of a childhood malignancy as well as in 460 age-and sex-matched healthy subjects who served as controls. The follow-up period for the effects of the anticancer therapy ranged from 11 to 43 months.
RESULTS: Compared to the controls, a significant increase in the frequency of the GSTP1b/GSTP1b genotype (odds ratio (OR) 5.7; 95% confidence limit (CL) from 2.4 to 13.8; Pearsons Chi-square P = 0.0001) was detected in the children with neoplasms. The GSTM1 and GSTT1 genotypes did not show any correlation with the risk of the de novo diagnosed neoplasms. During the observation, 62 children (26%) were found to be present with a local or disseminated recurrence of the diseases. The analysis indicated a trend in increasing risk of relapse for carriers of the GSTP1a allele (OR = 3.29; 95% CL from 0.73 to 14.67 P = 0.03).
CONCLUSIONS: Our results support the hypothesis that GST genotype affects etiology and outcome of a variety of childhood malignancies.

Gallegos-Arreola MP, Gómez-Meda BC, Morgan-Villela G, et al.
GSTT1 gene deletion is associated with lung cancer in Mexican patients.
Dis Markers. 2003-2004; 19(6):259-61 [PubMed] Free Access to Full Article Related Publications
Glutathione S-transferase (GST) is a dimeric detoxifying isoenzyme, involved in the deactivation of carcinogens, several tobacco-derived carcinogens, and xenobiotics. It catalyzes the reduction of glutathione to its thioester; thus, deficiency in GST activity due to homozygous deletion of the GSTT1 gene (null genotype) may play a role in the induction of lung cancer by smoking. We studied the distribution of GSTT1 gene deletion in peripheral blood DNA samples from 178 healthy controls (41 nonsmokers, 63 passive smokers and 74 smokers) and 52 lung cancer patients. Comparisons between groups showed that there was an increased lung cancer risk for individuals with the GSTT1 null genotype. Cancer patients showed significant differences when compared with controls: nonsmokers, passive smokers, and smokers. Twenty-one percent of lung cancer patients carried the deletion versus 2% among nonsmokers not exposed to passive smoking, 6% among passive smokers, and 5% among smokers. Thus, there is a significant association between this genotype and the possibility to risk of developing lung cancer.

Colombo J, Rossit AR, Caetano A, et al.
GSTT1, GSTM1 and CYP2E1 genetic polymorphisms in gastric cancer and chronic gastritis in a Brazilian population.
World J Gastroenterol. 2004; 10(9):1240-5 [PubMed] Free Access to Full Article Related Publications
AIM: To test the hypothesis that, in the Southeastern Brazilian population, the GSTT1, GSTM1 and CYP2E1 polymorphisms and putative risk factors are associated with an increased risk for gastric cancer.
METHODS: We conducted a study on 100 cases of gastric cancer (GC), 100 cases of chronic gastritis (CG), and 150 controls (C). Deletion of the GSTT1 and GSTM1 genes was assessed by multiplex PCR. CYP2E1/PstI genotyping was performed using a PCR-RFLP assay.
RESULTS: No relationship between GSTT1/GSTM1 deletion and the c1/c2 genotype of CYP2E1 was observed among the three groups. However, a significant difference between CG and C was observed, due to a greater number of GSTT1/GSTM1 positive genotypes in the CG group. The GSTT1 null genotype occurred more frequently in Negroid subjects, and the GSTM1 null genotype in Caucasians, while the GSTM1 positive genotype was observed mainly in individuals with chronic gastritis infected with H pylori.
CONCLUSION: Our findings indicate that there is no obvious relationship between the GSTT1, GSTM1 and CYP2E1 polymorphisms and gastric cancer.

Spivack SD, Hurteau GJ, Fasco MJ, Kaminsky LS
Phase I and II carcinogen metabolism gene expression in human lung tissue and tumors.
Clin Cancer Res. 2003; 9(16 Pt 1):6002-11 [PubMed] Related Publications
PURPOSE: The regulation of carcinogen metabolism machinery may involve proximate tobacco smoke exposure, hormonal and other endogenous coregulatory factors, and an individual's underlying genetic responsiveness. The mRNA and protein expression patterns of known carcinogen metabolism genes encoding the aromatic hydrocarbon receptor Ahr; the cytochromes P450 CYP1A1 and CYP1B1; glutathione S-transferases GSTM1, GSTM3, GSTP1, and GSTT1; and NADPH quinone oxidoreductase NQO1 were examined.
EXPERIMENTAL DESIGN: Paired tumor and nontumor lung tissue from 45 subjects was subject to a recently devised RNA-specific qualitative reverse transcription-PCR strategy, as well as Western immunoblotting. Tobacco exposure measured by plasma biomarkers nicotine and cotinine, plasma estradiol levels, alpha and beta estrogen receptor (ER) expression in the lung, gender, age, and histological diagnosis were then analyzed using multivariate regression models.
RESULTS: In nontumor lung tissue, multivariate models identified several correlates of mRNA expression: (a) CYP1B1 in females (positively: smoke status, P=0.024; ER-beta expression, P=0.024); (b) GSTT1 in females (positively: cotinine, P=0.007; negatively: age, P=0.001; ER-beta expression, P=0.005) and in males (positively: plasma estradiol, P=0.015; ER-beta expression, P=0.025); and (c) NQO1 in females (positively: smoke status, P=0.002) and in males (positively: ER-beta expression, P=0.001). CYP1A1 (mRNA, 9.1%) and GSTM1 (mRNA, 17.5%) are uncommonly expressed in human lung. Confirmation by Western immunoassayed protein is described. The results in nontumor tissue differed from that in tumor tissue.
CONCLUSIONS: Regulation of carcinogen metabolism genes expressed in human lung seems impacted by hormonal and gender factors, as well as ongoing tobacco exposure. Expression differences between tumor and nontumor tissue in this pathway have both susceptibility and therapeutic implications.

Yoshimura K, Hanaoka T, Ohnami S, et al.
Allele frequencies of single nucleotide polymorphisms (SNPs) in 40 candidate genes for gene-environment studies on cancer: data from population-based Japanese random samples.
J Hum Genet. 2003; 48(12):654-8 [PubMed] Related Publications
Knowledge of genetic polymorphisms in gene-environment studies may contribute to more accurate identification of avoidable risks and to developing tailor-made preventative measures. The aim of this study was to describe the allele frequencies of single nucleotide polymorphisms (SNPs) of select genes, which may be included in future gene-environment studies on cancer in Japan. SNP typing was performed on middle-aged Japanese men randomly selected from the general population in five areas of Japan. We genotyped and calculated allele frequencies of 153 SNPs located on 40 genes: CYP1A1, CYP1B1, CYP2C9, CYP2C19, CYP2E1, CYP17A1, CYP19A1, AHR, ESR1, ESR2, ERRRG, PGR, EPHX1, EPHX2, HSD17B2, HSD17B3, GSTM2, GSTM3, GSTT2, GSTP1, NAT1, NAT2, COMT, ADH1A, ADH1B, ADH1C, ALDH2, NOS2A, NOS3, IL1A, IL1B, OGG1, NUDT1 [MTH1], DRD2, DRD3, DRD4, SLC6A4, NR3C1 [GCCR], MTHFR, and NQO1. In the present study, the Japanese allele frequencies were verified by using nationwide population samples.

Landi S
Mammalian class theta GST and differential susceptibility to carcinogens: a review.
Mutat Res. 2000; 463(3):247-83 [PubMed] Related Publications
Glutathione S-transferases (GSTs) are an important part of the cellular detoxification system and, perhaps, evolved to protect cells against reactive oxygen metabolites. Theta is considered the most ancient among the GSTs and theta-like GSTs are found in mammals, fish, insects, plants, unicellular algae, and bacteria. It is thought that an ancestral theta-gene underwent an early duplication before the divergence of fungi and animals and further duplications generated the variety of the other classes of GSTs (alpha, mu, phi, etc.). The comparison of the aminoacidic homologies among mammals suggests that a duplication of an ancient GST theta occurred before the speciation of mammals and resulted in the subunits GSTT1 and GSTT2. The ancestral GST theta has a dehalogenase activity towards several halogenated compounds, such as the dichloromethane. In fact, some aerobic and anaerobic methylotrophic bacteria can use these molecules as the sole carbon and energy source. The mammalian GST theta cannot sustain the growth of bacteria but still retains the dehalogenating activity. Therefore, although mammalian GST theta behaves as a scavenger towards electrophiles, such as epoxides, it acts also as metabolic activator for halogenated compounds, producing a variety of intermediates potentially dangerous for DNA and cells. For example, mice exposed to dichloromethane show a dose-dependent incidence of cancer via the GSTT1-1 pathway. Because GSTT1-1 is polymorphic in humans, with about 20% of Caucasians and 80% of Asians lacking the enzyme, the relationship between the phenotype and the incidence of cancer has been investigated extensively in order to detect GSTT1-1-associated differential susceptibility towards endogenous or exogenous carcinogens. The lack of the enzyme is related to a slightly increased risk of cancer of the bladder, gastro-intestinal tract, and for tobacco-related tumors (lung or oral cavity). More pronounced risks were found in males with the GSTT1-null genotype for brain diseases and skin basal cell carcinomas not related to sunlight exposures. Moreover, there was an increased risk of kidney and liver tumors in humans with the GSTT1-1 positive genotype following exposures to halogenated solvents. Interestingly, the liver and kidney are two organs that express the highest level of GST theta in the human body. Thus, the GSTT1-1 genotype is suspected to confer decreased or increased risk of cancer in relation to the source of exposure; in vitro studies, mostly conducted on metabolites of butadiene, confirm the protective action of GSTT1-1, whereas, thus far, experimental studies prove that the increasing risk is limited.

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