Association between glutathione S-transferase M1, P1, and T1 genetic polymorphisms and development of breast cancer

Prenatal exposure to maternal smoking and adult lung cancer risk: a nested case-control study using peripheral blood leukocyte DNA methylation prediction of exposure

A prior study reported no association between prenatal smoking methylation scores and adult lung cancer risk adjusting for methylation-predicted adult smoking, without considering maternal smoking trends by birth cohort. To address this gap, we examined the association between prenatal smoking methylation scores and adult lung cancer, independent of methylation-predicted adult packyears and by birth cohort, in a study nested in CLUE II. Included were 208 incident lung cancer cases ascertained by cancer registry linkage and 208 controls matched on age, sex, and smoking. DNA methylation was measured in prediagnostic blood. We calculated two prenatal smoking scores, using 19 (Score-19) and 15 (Score-15) previously identified CpGs and a methylation-predicted adult packyears score. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) adjusting for adult packyears score and batch effects. Score-15 was positively associated with lung cancer (per standard deviation, OR = 1.40, 95% CI = 1.10-1.79, P-trend = .006), especially in the 1930-1938 birth cohort (OR = 3.43, 95% CI = 1.55-7.60, P-trend = .002). Score-19 was associated only in the 1930-1938 birth cohort (OR = 2.12, 95% CI = 1.15-3.91). Participants with both prenatal scores below the median (vs all other combinations) had lower risk (OR = 0.44, 95% CI = 0.27-0.72), especially in the 1930-1938 birth cohort (OR = 0.16, 95% CI = 0.04-0.62). Among ever smokers, participants with higher prenatal smoking scores had higher risk, irrespective of adult packyears (low: OR = 2.81, 95% CI = 1.38-5.72, high: OR = 2.67, 95% CI = 1.03-6.95). This prospective study suggests a positive association between prenatal smoking exposure and adult lung cancer risk, especially in the 1930-1938 birth cohort, independent of active smoking. Future studies with multiple birth cohorts are needed.

Polymorphism of glutathione S-transferase P1 of dogs with mammary tumours

Mammary tumours constitute more than half of neoplasms in female dogs from different countries. Genome sequences are associated with cancer susceptibility but there is little information available about genetic polymorphisms of glutathione S-transferase P1 (GSTP1) in canine cancers. The aim of this study was to find single nucleotide polymorphisms (SNPs) in GSTP1 of dogs (Canis lupus familiaris) with mammary tumours compared to healthy dogs and to determine the association between GSTP1 polymorphisms and the occurrence of these tumours. The study population included 36 client-owned female dogs with mammary tumours and 12 healthy female dogs, with no previous diagnosis of cancer. DNA was extracted from blood and amplified by PCR assay. PCR-products were sequenced by Sanger method and analysed manually. The 33 polymorphisms were found in GSTP1: 1 coding SNP (exon 4), 24 non-coding SNPs (9 in exon 1), 7 deletions and 1 insertion. The 17 polymorphisms have been found in introns 1, 4, 5 and 6. The dogs with mammary tumours have significant difference from healthy in SNPs I4 c.1018 + 123 T > C (OR 13.412, 95%CI 1.574-114.267, P = .001), I5 c.1487 + 27 T > C (OR 10.737, 95%CI 1.260-91.477, P = .004), I5 c.1487 + 842 G > C (OR 4.714, 95% CI 1.086-20.472, P = .046) and I6 c.2481 + 50 A > G (OR 12.000, 95% CI 1.409-102.207, P = .002). SNP E5 c.1487 T > C and I5 c.1487 + 829 delG also differed significantly (P = .03) but not to the confidence interval. The study, for the first time, showed a positive association of SNPs in GSTP1 with mammary tumours of dogs, that can possibly be used to predict the occurrence of this pathology.

Evaluation of molecular markers GSTM1 and GSTT1 and clinical factors in breast cancer: case-control study and literature review

The study was conducted to evaluate the frequency of polymorphisms in GSTM1 and GSTT1 genes in patients with breast cancer compared with individuals without history of cancer, and the association of these polymorphisms with clinical/epidemiological parameters.There were evaluated 752 women (219 patients and 533 controls). Molecular analysis was performed by the Polymerase Chain Reaction (PCR). Statistical analysis was used multiple logistic regression and descriptive statistics.Age ≥50 years (OR =3.22, 95% CI =2.30 - 4.51, p <0.001) and alcohol consumption (OR =1.60, 95% CI =1.13 - 2.27, p = 0.008) were associated to the development of breast cancer, while smoking and null genotypes GSTM1 and GSTT1 presented no association. GSTM1 and GSTT1 polymorphisms presented no relationship with the clinical and histopathological parameters or molecular subtypes of breast cancer. Ninety-two percent of tumors were invasive ductal, 66% were grade II, 65% were larger than 2 cm, the stages II (35.3%) and III (31.2%) were the most prevalent, and 47.7% were molecular subtype luminal B.Individuals aged ≥50 years and alcohol consumers have more chance to developing breast cancer. GSTM1 and GSTT1 polymorphisms are not associated to the risk of breast cancer.

The association of glutathione S-transferase T1 and M1 deletions with myocardial infarction

Glutathione S-transferases (GSTs) are the family of enzymes involved in the second line of defense against oxidative stress (OS). The lack of GSTT1/GSTM1 enzyme quantity or activity, due to the presence of homozygous deletion compromises antioxidative defense resulting in OS. OS is the critical mechanism in the pathophysiology of atherosclerosis, coronary artery disease, and myocardial infarction (MI). The increase in reactive oxygen species together with the process of apoptosis plays a role in left ventricular remodeling (LVR) after MI. The associations of GSTT1 and GSTM1 gene polymorphisms with the risk of MI are inconsistent. The aim was to analyze the association of GSTT1/GSTM1 null genotypes with first MI and LVR 8 months after the MI. The study involved 330 controls and 438 consecutive patients with symptoms and signs of first MI. The subgroup of 150 MI patients was prospectively followed up for 6 months. Evidence of maladaptive LVR was obtained by 2D Doppler echocardiography 3-5 days and 6 months after the MI. A multiplex polymerase chain reaction was used to detect the deletion in GSTT1 and GSTM1 genes. GSTM1 null genotype was significantly and independently associated with first MI (adjusted OR = 1.45 95% CI 1.03-2.03, p = 0.03). Association of double null genotypes with maladaptive LVR in patients 6 months after the first MI was no longer significant after adjustment for factors that differed significantly between patients with and without maladaptive LVR. This study demonstrated the association of GSTM1 null genotypes with the risk of MI in the Serbian population.

Glutathione-coordinated metal complexes as substrates for cellular transporters

Glutathione is the major thiol-containing species in both prokaryotes and eukaryotes and plays a wide variety of roles, including detoxification of metals by sequestration, reduction, and efflux. ABC transporters such as MRP1 and MRP2 detoxify the cell from certain metals by exporting the cations as a metal-glutathione complex. The ability of the bacterial Atm1 protein to efflux metal-glutathione complexes appears to have evolved over time to become the ABCB7 transporter in mammals, located in the inner mitochondrial membrane. No longer needed for the role of cellular detoxification, ABCB7 appears to be used to transport glutathione-coordinated iron-sulfur clusters from mitochondria to the cytosol.

Impact of xenobiotic-metabolizing gene polymorphisms on breast cancer risk in South Indian women

BACKGROUND

Functional variants of the xenobiotic-metabolizing genes (XMG) might modulate breast cancer (BC) risk by altering the rate of metabolism and clearance of myriad types of potent carcinogens from the breast tissue. Despite mounting evidence on the role of XMG variants on BC risk, the current knowledge regarding their influence on BC development is still fragmentary.

METHODS

The present study examined the candidate genetic variants in CYP1A1, NQO1, GST-T1, GST-M1, and GST-P1 in 1002 subjects (502 BC patients and 500 disease-free women). PCR-RFLP was employed to genotype the mono-nucleotide variation in CYP1A1, NQO1, and GST-P1, and allele-specific PCR was used to detect the deletion polymorphism in GST-T1 and GST-M1 genes.

RESULTS

Regarding CYP1A1-M1 polymorphism, the heterozygous TC and mutant CC genotype conferred 1.47-fold (95% CI 1.13-1.91, p = 0.004) and 1.84-fold (95% CI 1.17-2.91, p = 0.009) elevated risk of BC. GST-T1 null genotype was associated with increased BC risk (OR 1.47; 95% CI 1.02-2.11, p = 0.037). For the NQO1 C609T variant, the mutant T allele was associated with BC risk with an odds ratio of 1.22 (95% CI 1.02-1.48, p = 0.034). Combinatorial analysis indicated that the presence of NQO1*2 (CT), CYP1A1-M1 (CC), and GST-P1 rs1695 (AG) genotypes conferred 16.7-fold elevated risk of BC (95% CI 3.65-76.85; p < 0.001). Moreover, GST-M1 null genotype was associated with the development of larger primary breast tumors.

CONCLUSION

Xenobiotic-metabolizing gene polymorphisms may play a crucial role in mammary carcinogenesis in South Indian women.

Sustained Weight Loss and Risk of Breast Cancer in Women 50 Years and Older: A Pooled Analysis of Prospective Data

BACKGROUND

Excess body weight is an established cause of postmenopausal breast cancer, but it is unknown if weight loss reduces risk.

METHODS

Associations between weight change and risk of breast cancer were examined among women aged 50 years and older in the Pooling Project of Prospective Studies of Diet and Cancer. In 10 cohorts, weight assessed on three surveys was used to examine weight change patterns over approximately 10 years (interval 1 median = 5.2 years; interval 2 median = 4.0 years). Sustained weight loss was defined as no less than 2 kg lost in interval 1 that was not regained in interval 2. Among 180 885 women, 6930 invasive breast cancers were identified during follow-up.

RESULTS

Compared with women with stable weight (±2 kg), women with sustained weight loss had a lower risk of breast cancer. This risk reduction was linear and specific to women not using postmenopausal hormones (>2-4.5 kg lost: hazard ratio [HR] = 0.82, 95% confidence interval [CI] = 0.70 to 0.96; >4.5-<9 kg lost: HR = 0.75, 95% CI = 0.63 to 0.90; ≥9 kg lost: HR = 0.68, 95% CI = 0.50 to 0.93). Women who lost at least 9 kg and gained back some (but not all) of it were also at a lower risk of breast cancer. Other patterns of weight loss and gain over the two intervals had a similar risk of breast cancer to women with stable weight.

CONCLUSIONS

These results suggest that sustained weight loss, even modest amounts, is associated with lower breast cancer risk for women aged 50 years and older. Breast cancer prevention may be a strong weight-loss motivator for the two-thirds of American women who are overweight or obese.

The reference genome of the selfing fish Kryptolebias hermaphroditus: Identification of phases I and II detoxification genes

The selfing fish Kryptolebias hermaphroditus has unique reproductive system for self-fertilization, making genetically homozygous offsprings. Here, we report on high density genetic map-based genome assembly for the K. hermaphroditus Panama line (PanRS). The numbers of scaffolds were 5212 and the genome was 683,992,224 bp (N50 = 27.45 Mb). The length of anchored scaffold onto 24 linkage groups was 652,231,070 bp (95.3% of genome) with 0.01% of the gap and 39.33% of GC content and complete Benchmarking Universal Single-Copy Orthologs value was 96.6%. The numbers of annotated genes were 36,756 (average gene length 1368 bp) with the GC content of 54.1%. To examine the difference between the two sister species in the genus Kryptolebias, we compared the genomes of K. hermaphroditus PanRS and Kryptolebias marmoratus PAN line on the composition of transposable elements. To demonstrate applications of genome library, phase I and II detoxification related gene families have been analyzed, and compared the syntenies containing loci of CYP and GST genes on linkage groups. This K. hermaphroditus genome information will be helpful for a better understanding on genome-wide mechanistic view of detoxification and antioxidant-related genes over evolution in the view of fish environmental ecotoxicology.

Genetic Polymorphism of GSTP-1 Affects Cyclophosphamide Treatment of Autoimmune Diseases

Cyclophosphamide is one of the most potent and reliable anti-cancer and immunosuppressive drugs. In our study, 33 individuals with different autoimmune diseases were treated with cyclophosphamide according to standard protocols. The responses to the treatments were determined by measuring the alteration of several typical parameters characterizing the given autoimmune diseases over time. We concluded that about 45% of the patients responded to the treatment. Patients were genotyped for polymorphisms of the CYP3A4, CYP2B6, GSTM1, GSTT1, and GSTP1 genes and disease remission cases were compared to the individual polymorphic genotypes. It was found that the GSTP1 I105V allelic variation significantly associated with the cyclophosphamide treatment-dependent disease-remissions. At the same time the GSH content of the erythrocytes in the patients with I105V allelic variation did not change. It appears that the individuals carrying the Ile105Val SNP in at least one copy had a significantly higher response rate to the treatment. Since this variant of GSTP1 can be characterized by lower conjugation capacity that results in an elongated and higher therapeutic dose of cyclophosphamide, our data suggest that the decreased activity of this variant of GSTP1 can be in the background of the more effective disease treatment.

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.

Association Of GSTM1, GSTT1 And GSTP1 Polymorphisms With Breast Cancer Among Jordanian Women

Purpose

Genetic predisposition to disease has become one of the most investigated risk factors in recent years, and breast cancer (BC) is no exception. In this study, we investigated specific genetic variants of three candidate genes belonging to the glutathione-S-transferase superfamily that have been implicated in increased risk of cancers.

Materials and methods

This case-control study comprised 241 Jordanian women who were diagnosed with BC in addition to 219 matched controls. Gel electrophoresis of PCR products was used to visualize and genotype both the GSTM1 and GSTT1 genes, while PCR-RFLP was employed to genotype the rs1695 of the GSTP1 gene.

Results

Our findings did not reveal any correlation between the investigated polymorphisms of GST genes and BC risk among Jordanian women. Otherwise, the combination of GSTM1 entire gene deletion and (GG) genotype of GSTP1 polymorphism (rs1695) was significantly associated with BC with p-value <0.05 (i.e. p-value was not significant after correcting for multiple comparison).

Conclusion

We suggest that the interaction between GSTM1 polymorphism and rs1695 of GSTP1 may influence BC development and progression among Jordanian women. More epidemiological studies are needed to provide a baseline for the underlying role of GSTs polymorphisms in tumorigenesis.

Combined effects of GSTM1 and GSTT1 polymorphisms on breast cancer risk: A MOOSE-compliant meta-analysis and false-positive report probabilities test

Many molecular epidemiology studies have reported an association between the combined effects of glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) polymorphisms on breast cancer risk. However, the results have been controversial.A meta-analysis was performed to clarify this issue.Meta-analysis of observational studies in epidemiology guidelines was used. Pooled the crude odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random-effects model or fixed-effects model. Several subgroup analyses were conducted by ethnicity, source of control, matching, and menopausal status. In addition, we also performed sensitivity analysis and publication bias. Moreover, a false-positive report probability (FPRP) test was applied to assess positive results.A significantly increased breast cancer risk was observed in overall population (GSTM1 null/GSTT1 present [- +] vs GSTM1 present/GSTT1 present [+ +]: OR = 1.19, 95% CI: 1.03-1.36, GSTM1 null/GSTT1 null [- -] vs + +: OR = 1.63, 95% CI: 1.29-2.06, (- +) + GSTM1 present/GSTT1 null (+ -) vs + +: OR = 1.17, 95% CI: 1.05-1.31, (- +) + (+ -) + (- -) vs + +: OR = 1.27, 95% CI: 1.12-1.44, and - - vs (- +) + (+ -) + (+ +): OR = 1.39, 95% CI: 1.17-1.66) and several subgroup analyses, such as Caucasians, Indians, postmenopausal women, and so on. However, positive results were only considered noteworthy in overall population (- - vs + +: FPRP = 0.150 and (- +) + (+ -) + (- -) vs + +: FPRP = 0.162). Moreover, no significant association was observed when we used the trim and fill method to adjust the pooled data from all populations. Further, none of positive results of sensitivity analysis were considered noteworthy (FPRP >0.2).These positive findings should be interpreted with caution and indicate that an increased breast cancer risk may most likely result from false-positive results, rather than from true associations or biological factors on the combined effects of GSTM1 and GSTT1. Future studies should be based on sample sizes well-powered and attention needs to be paid to study design to further identify this issue.

Glutathione S-transferase omega gene polymorphism as a biomarker for human papilloma virus and cervical cancer in Iranian women

Objective

Human papillomavirus (HPV) infection is an important sexually-transmitted infection worldwide. Persistent infections with different high-risk HPV genotypes may cause cervical intraepithelial neoplasia and cervical cancer. Single nucleotide polymorphisms of glutathione S-transferase omega (GSTO) 1 and 2 play an important role in cancer progression. To evaluate GSTO gene polymorphism influence on women’s susceptibility to low-risk or high-risk HPV infections and also risk of cervical cancer development.

Material and Methods

We examined 50 patients with cervical cancer, 43 patients who were positive for HPV, and 43 healthy individuals as negative controls. We used polymerase chain reaction-restriction fragment length polymorphism to determine GSTO1 A140D and GSTO2 N142D variants in study participants.

Results

We found a significant association between the GSTO1 A140D gene polymorphism and HPV 6, 16, 18, 16/18 infections and cervical cancer in Iranian women. We noted a significant difference for the 140AD/142NN combination genotype between patients in the cervical cancer group and healthy controls. There were no significant differences for the GSTO2 N142D genotype and allele frequencies between the patient (i.e., cervical cancer and HPV-positive) groups and controls.

Conclusion

The 140AD genotype, 140D allele, and 140AD/142NN combination genotype seem to confer a protective property in women’s susceptibility to HPV 6, 16, 18, 16/18 infections and cervical cancer. However, the GSTO2 N142D polymorphism is not associated with HPV infections and cervical cancer. It would appear that GSTO1 A140D SNPs likely play a role in the level of susceptibility to HPV-related cervical cancer.

Chemotherapy-Induced Ca2+ Release Stimulates Breast Cancer Stem Cell Enrichment

Breast cancer stem cells (BCSCs) play a critical role in tumor recurrence and metastasis. Exposure of breast cancer cells to chemotherapy leads to an enrichment of BCSCs. Here, we find that chemotherapy induces the expression of glutathione S-transferase omega 1 (GSTO1), which is dependent on hypoxia-inducible factor 1 (HIF-1) and HIF-2. Knockdown of GSTO1 expression abrogates carboplatin-induced BCSC enrichment, decreases tumor initiation and metastatic capacity, and delays tumor recurrence after chemotherapy. GSTO1 interacts with the ryanodine receptor RYR1 and promotes calcium release from the endoplasmic reticulum. Increased cytosolic calcium levels activate PYK2 → SRC → STAT3 signaling, leading to increased expression of pluripotency factors and BCSC enrichment. HIF inhibition blocks chemotherapy-induced GSTO1 expression and BCSC enrichment. Combining HIF inhibitors with chemotherapy may improve clinical outcome in breast cancer.

Polymorphisms and mutations in GSTP1, RAD51, XRCC1 and XRCC3 genes in breast cancer patients

BACKGROUND

Genotoxic factors, including ionizing radiation and oxidative stress, are associated with genomic instability and development of breast cancer (BC). The homologous recombination DNA repair (HRR) pathway, base excision repair (BER) mechanism, and antioxidative enzymes are required as defense mechanisms against these DNA damaging agents. GSTP1, XRCC1, XRCC3 and RAD51 proteins are essential components of antioxidation, BER and HRR of DNA, respectively. Deficiencies in BER, HRR and antioxidation pathways are involved in the progression of cancer.

METHODS

Genomic DNA was extracted from formalin-fixed, paraffin-embedded tissue and blood samples of BC patients of an Italian population. Genomic DNA was also extracted from blood specimens of a control group. DNA sequencing was performed for six single-nucleotide polymorphisms (SNPs) in the GSTP1, RAD51, XRCC1 and XRCC3 genes in BC patients and the control group.

RESULTS

Two variants in the 5'-UTR of the XRCC3 (rs1799794 A/G) and RAD51 (rs1801321) genes showed a significant association with susceptibility to BC (OR = 4.125; 95% CI 1.057-16.102; p = 0.03 and OR = 2.04; 95% CI 0.4925-8.449; p = 0.007, respectively). Additionally, we reported 2 mutations in intron 7 of the XRCC3 gene, CTdel (rs543072564) and A/G (rs369703243).

CONCLUSIONS

Our results underscored the existence of an association between XRCC3-5'-UTR-A/G (rs1799794) and RAD51-5'-UTR G172T (rs1801321) genotypes and BC risk in an Italian population. The presence of mutations in the intronic region of the XRCC3 gene highlights the importance of more sequence screening of DNA repair genes for possible genetic penetrance in BC.

Obesity and Breast Cancer: Molecular Interconnections and Potential Clinical Applications

Obesity is an important risk factor for breast cancer (BC) in postmenopausal women; interlinked molecular mechanisms might be involved in the pathogenesis. Increased levels of estrogens due to aromatization of the adipose tissue, inflammatory cytokines such as tumor necrosis factor-α, interleukin-6, and prostaglandin E2, insulin resistance and hyperactivation of insulin-like growth factors pathways, adipokines, and oxidative stress are all abnormally regulated in obese women and contribute to cancerogenesis. These molecular factors interfere with intracellular signaling in the mitogen-activated protein kinase and phosphatydilinositol-3-phosphate/mammalian target of rapamycin (mTOR) pathways, which regulate the progression of the cell cycle, apoptosis, and protein synthesis. In this context, structural defects of typical genes related to both BC and obesity, such as leptin, leptin receptor, serum paraoxonase/arylesterase 1, the fat mass and obesity-associated gene and melanocortin receptor 4, have been associated with a high or low risk of BC development. The early detection of these gene alterations might be useful as risk predictors in obese women, and targeting these pathways involved in the BC pathogenesis in obese women is a potential therapeutic tool. In particular, mTOR pathway deregulation concurs in both obesity and BC, and inhibition of this might disrupt the molecular interlinks in a similar manner to that of metformin, which exerts definite anticancer activity and is currently used as an antidiabetic drug with a weight-reducing property. The identification of both genetic and pharmacological implications on the prevention and management of BC is the ultimate aim of these studies.

IMPLICATIONS FOR PRACTICE

Obese women are at risk of breast cancer, but clinicians lack concrete tools for the prevention or early diagnosis of this risk. The present study, starting from the biology and the molecular defects characterizing both obesity and breast cancer, analyzed the potential molecules and genetic defects whose early identification could delineate a risk profile. Three steps are proposed that are potentially achievable in the clinical assessment of obese women, namely the evaluation of altered levels of serum molecules, the identification of genetic polymorphisms, and the study of the transcriptomic profile of premalignant lesions. Finally, the therapeutic implications of this molecular assessment were evaluated.

Drug-metabolizing and antioxidant enzymes in monosodium L-glutamate obese mice

The prevalence of obesity is rapidly increasing across the world. Physiologic alterations associated with obesity are known to alter enzyme expression and/or activities. As drug-metabolizing and antioxidant enzymes serve as defense system against potentially toxic compounds, their modulation might have serious consequences. In this work, we studied selected antioxidant and drug-metabolizing enzymes (DME) in monosodium glutamate-mouse model of obesity. Specific activities, protein, and mRNA expressions of these enzymes in liver as well as in small intestine were compared in obese male mice and in their lean counterparts. Furthermore, expression of the NF-E2-related factor 2 (Nrf2) and its relation to obesity were tested. Obtained results showed that obesity affects expression and/or activities of some DME and antioxidant enzymes. In obese mice, upregulation of UDP-glucuronosyltransferases 1A (UGT1A), NAD(P)H:quinone oxidoreductase 1 (NQO1), nuclear transcription factor Nrf2, and downregulation of some isoforms of glutathione S-transferases (GST) were observed. Most of these changes were tissue and/or isoform specific. NQO1 seems to be regulated transcriptionally via Nrf2, but other enzymes might be regulated post-transcriptionally and/or post-translationally. Enhanced expression of Nrf2 in livers of obese mice is expected to play a role in protective adaptation. In contrast, elevated activities of NQO1 and UGT1A may cause alterations in drug pharmacokinetics in obese individuals. Moreover, decreased capacity of GST in obese animals indicates potentially reduced antioxidant defense and weaker chemoprotection.

Indoor air pollution exposure from use of indoor stoves and fireplaces in association with breast cancer: a case-control study

BACKGROUND

Previous studies suggest that polycyclic aromatic hydrocarbons (PAHs) may adversely affect breast cancer risk. Indoor air pollution from use of indoor stoves and/or fireplaces is an important source of ambient PAH exposure. However, the association between indoor stove/fireplace use and breast cancer risk is unknown. We hypothesized that indoor stove/fireplace use in a Long Island, New York study population would be positively associated with breast cancer and differ by material burned, and the duration and timing of exposure. We also hypothesized that the association would vary by breast cancer subtype defined by p53 mutation status, and interact with glutathione S-transferases GSTM1, T1, A1 and P1 polymorphisms.

METHODS

Population-based, case-control resources (1,508 cases/1,556 controls) were used to conduct unconditional logistic regression to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Breast cancer risk was increased among women reporting ever burning synthetic logs (which may also contain wood) in their homes (OR = 1.42, 95% CI 1.11, 1.84), but not for ever burning wood alone (OR = 0.93, 95% CI 0.77, 1.12). For synthetic log use, longer duration >7 years, older age at exposure (>20 years; OR = 1.65, 95% CI 1.02, 2.67) and 2 or more variants in GSTM1, T1, A1 or P1 (OR = 1.71, 95% CI 1.09, 2.69) were associated with increased risk.

CONCLUSIONS

Burning wood or synthetic logs are both indoor PAH exposure sources; however, positive associations were only observed for burning synthetic logs, which was stronger for longer exposures, adult exposures, and those with multiple GST variant genotypes. Therefore, our results should be interpreted with care and require replication.

Prospective Case-Control Study to Evaluate the Role of Glutathione S Transferases (GSTT1 and GSTM1) Gene Deletion in Breast Carcinoma and Its Prognostic Significance

Breast cancer is the most common cause of cancer death in women with the incidence rising in young women. GST gene polymorphisms are significant because of their role in the detoxification of both environmental carcinogens and also cytotoxic drugs used in therapy for breast cancer. The present study has been designed to identify the role of polymorphisms in GSTT1 and GSTM1 genes in the risk of development of breast cancer, in the prognostication of breast cancer, and in the prediction of response towards chemotherapy. Ninety-nine patients with breast cancer and 100 healthy controls with no history of cancer were taken from blood donors after informed consent. Epidemiological and clinical data was collected from participants and 5 ml of peripheral venous blood was collected for genotype analysis. Null genotype of GSTT1 was detected in 51.04 % of the controls in comparison to 20.2 % of patients with carcinoma breast, which was found to be statistically significant (OR 4.18; 95 % CI 2.01-8.75; P = 0.0001). GSTM1 gene deletion was also significantly more common among controls (60 %) than in patients with breast cancer (33 %) (OR 4.57; 95 % CI 2.20-9.51; P = 0.0001). Tumors more than 5 cm in size had greater tendency for GSTM1 gene expression (P value = 0.019), but other clinicopathological parameters did not show any correlation. GSTT1 and GSTM1 genes status did not show any association with response to chemotherapy. The results indicated the null genotype of both GSTT1 and GSTM1 to be protective for the development of carcinoma breast. None of the known etiological factors have any correlation with GSTT1 and GSTM1 gene deletion. Patients with small tumor size expressed GSTM1 gene deletion. Other tumor characteristics and clinicopathological parameters did not have any correlation with gene deletion.

Association study of SNPs of genes IFNGR1 (rs137854905), GSTT1 (rs71748309), and GSTP1 (rs1695) in gastric cancer development in samples of patient in the northern and northeastern Brazil

Cancer is a multifactorial disease with a high mortality rate in Brazil and worldwide. Gastric cancer (GC) is considered the fourth type of malignancy more frequent in the population worldwide and the second leading cause of death. This work aimed to evaluate single nucleotide polymorphisms (SNPs) of IFNGR1, GSTT1, and GSTP1 genes samples in gastric cancer. We analyzed 60 samples of gastric cancer, 26 diffuse and 34 intestinal types, totaling 120 alleles for each SNP. The results were obtained by PCR and allele-specific PCR. Statistical analyzes performed using BioEstat 5.0 software, applying the Fisher's exact test and chi-square. Only the SNP gene GSTP1 (rs1695) were significantly associated with gastric cancer in the samples analyzed (χ(2) = 8.73, P < 0.05). Our results suggest that the GSTP1 gene SNP (rs1695) can be considered a risk factor associated with gastric carcinogenesis.

Quantitative assessment of the effect of glutathione S-transferase genes GSTM1 and GSTT1 on hepatocellular carcinoma risk

Hepatocellular carcinoma (HCC) is one of the most serious health problems worldwide. As in many other diseases, environment and genetic factors are believed to be involved in the pathogenesis of HCC. Numerous epidemiologic investigations including case-control and cohort studies have suggested the association of glutathione S-transferase (GST) genetic polymorphisms and HCC risk. However, some studies have produced conflicting results. Therefore, we performed an updated meta-analysis to clarify this inconsistency and to establish a comprehensive picture of the association of the polymorphisms of GSTM1 and GSTT1 with HCC susceptibility. We searched PubMed, Embase, ISI Web of Science, and CNKI databases to identify eligible studies meeting the inclusion criteria up to August 30, 2013. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of association. Finally, there were a total of 33 studies with 4,232 cases and 6,601 controls included in this meta-analysis. In the pooled analysis, significantly increased HCC risks were found for null genotype of GSTM1 (OR = 1.31, 95% CI = 1.07-1.61, P = 0.010, P heterogeneity < 10(-5)) and GSTT1 (OR = 1.47, 95% CI = 1.25-1.74, P < 10(-5), P heterogeneity < 10(-5)). Potential sources of heterogeneity were explored by subgroup analysis based on ethnicity, sample size, and source of control. Significant results were found among East Asians and Indians when stratified by ethnicity, while no evidence of significant associations was observed among Caucasian and African populations. In the gene-gene interaction analysis, a statistically significant increased risk for HCC was detected for individuals with combined deletion mutations in both genes compared to those with wild genotypes (OR = 1.88, 95% CI = 1.41-2.50, P < 10(-4), P heterogeneity = 0.004). The present meta-analysis demonstrated that the GSTM1 and GSTT1 null genotype may be associated with an increased risk of HCC and that individuals having the combination of both defective GST genotypes may be more susceptible to developing HCC.

GSTP1 gene Ile105Val polymorphism causes an elevated risk for bladder carcinogenesis in smokers

BACKGROUND

The glutathione S transferase (GST) family of enzymes plays a vital role in the phase II biotransformation of environmental carcinogens, pollutants, drugs and other xenobiotics. GSTs are polymorphic and polymorphisms in GST genes have been associated with cancer susceptibility and prognosis. GSTP1 is associated with risk of various cancers including bladder cancer. A case control study was conducted to determine the genotype distribution of GSTP1 A>G SNP, to elucidate the possible role of this SNP as a risk factor in urinary bladder cancer (UBC) development and to examine its correlation with clinico-pathologic variables inUBC cases.

MATERIALS AND METHODS

Using the polymerase chain reaction-restriction fragment length polymorphism (PCR- RFLP) approach, we tested the genotype distribution of 180 bladder cancer patients in comparison with 210 cancer-free controls from the same geographical region with matched frequency in age and gender.

RESULTS

We did not observe significant genotype differences between the control and bladder cancer patients overall with an odds ratio (OR)=1.23 (p>0.05). The rare allele (AG+GG) was found to be present more in cases (28.3%) than in controls (24%), though the association was not significant (p<0.05). However, a significant risk of more than 2-fold was found for the variant allele (AG+GG) with smokers in cases as compared to controls (p>0.05).

CONCLUSIONS

Thus, it is evident from our study that GSTP1 SNP is not implicated overall in bladder cancer, but that the rare, valine-related allele is connected with higher susceptibility to bladder cancer in smokers and also males.

The glutathione S-transferase T1 deletion is associated with susceptibility to multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) occurs as a result of interaction between genetic and environmental factors. Recent data support the view that oxidative damage is one of an early event in MS tissue injury. The safe elimination of reactive oxygen species and toxins via glutathione S-transferase (GST) pathways is required in order to protect cells against reactive oxygen-induced damage. The aim of our study was to analyze the possible association of GSTM1 and GSTT1 gene polymorphisms with the susceptibility and clinical parameters of MS, in 455 consecutive patients and 366 controls.

METHODS

A multiplex polymerase chain reaction (PCR) was used to detect the deletions in GSTM1 and GSTT1 genes.

RESULTS

Patients with MS had significantly higher frequency of GSTT1 null genotype compared to controls (37.36% vs. 21.86%, respectively, p<0.0001, adjusted OR 2.13 (1.56-2.90)), as well as double deletions (15.38% vs. 10.38%, respectively, p<0.05). The carriers of GSTM1 deletion had significantly earlier onset of MS compared to the wild-type carriers (28.31 ± 8.45 vs. 30.64 ± 9.30 years, respectively, p = 0.03).

CONCLUSION

This study suggests the potential pathogenic role of GSTT1 deletion on MS susceptibility. There are no similar data published so far, yet this study should be replicated in other populations.

Adipocytokines, inflammation, and breast cancer risk in postmenopausal women: a prospective study

Obesity is a known risk factor for postmenopausal breast cancer; it has been postulated that adipocytokines may mediate this association. We explored the relationship between three markers altered by obesity: leptin, adiponectin, and soluble tumor necrosis factor receptor 2 (sTNF-R2), an inflammatory marker, with breast cancer risk in postmenopausal women. A nested case-control study of postmenopausal women was conducted within CLUE II, a prospective population-based cohort. Baseline plasma levels of leptin, adiponectin, and sTNF-R2 were assayed in 272 female breast cancer cases and 272 controls matched on age, date, and hour of blood draw. Conditional logistic regression was used to estimate matched odds ratios (OR) and 95% confidence intervals (CI). sTNF-R2 and leptin were independently positively associated with breast cancer risk in adjusted models. The OR for breast cancer comparing the highest to lowest tertile was 2.44 (95% CI: 1.30-4.58) for sTNF-R2 and 1.98 (95% CI: 1.20-3.29) for leptin. While higher levels of adiponectin were protective (OR for the lowest tertile = 1.63; 95% CI: 1.02-2.60), there was no dose response. A 20% reduction in the breast cancer risk associated with overweight/obesity was observed when sTNF-R2 alone was included in multivariable models. Including both sTNF-R2 and adiponectin in the models resulted in a 29% reduction in the OR. Adipocytokines and sTNF-R2 are important factors in the etiology of postmenopausal breast cancer due to adiposity. This study informs our understanding of the relationship between obesity, inflammation, and postmenopausal breast cancer and identifies potential biomarkers.

The leptin gene family and colorectal cancer: interaction with smoking behavior and family history of cancer

BACKGROUND

Pathologic condition associated with metabolic syndrome traits seems to increase the risk of colorectal cancer. One mechanism underlying this relationship may involve the growth-promoting effects of the circulation hormones associated with obesity and insulin resistance, such as leptin.

METHODOLOGY/PRINCIPAL FINDINGS

A two-stage case-control study was used to explore the role of polymorphisms of Leptin (LEP) and Leptin receptor (LEPR), either alone or in combination with environmental factors in colorectal carcinogenesis. In stage 1, 20 single nucleotide polymorphisms (SNPs) that tag common SNPs in these two genes were genotyped among 470 cases and 458 controls. In stage 2, another population with 314 cases and 355 controls were genotyped for the two most promising SNPs from stage 1. LEPR rs12037879 only presented modestly increased colorectal cancer risk, with odds ratios of 1.41 (95% confidence interval [CI] 1.13-1.76) and 1.74 (95%CI 1.08-2.81) for GA and AA genotype when compared with GG genotype in combined population. Smokers carrying LEPR rs12037879 A allele presented 1.67-fold (95%CI 1.39-fold to 2.01-fold) increased colorectal cancer risk when compared with non-smokers carrying GG genotype in combined analysis. Individuals with family history of cancer harboring LEPR rs12037879 A allele showed 1.52-fold (95%CI: 1.24-fold to 1.86-fold) increased colorectal cancer risk, compared with individuals without family history of cancer harboring GG genotype. Multifactor gene-environment interaction analysis revealed significant interactions among LEPR rs12037879, LEPR rs6690625, smoking status and family history of cancer, exhibiting a gradient of increased colorectal cancer risk along with the increasing number of risk factors (P = 9.82 × 10(-10)).

CONCLUSIONS/SIGNIFICANCE

Our research supports that polymorphisms in LEPR may be associated with marginal increase in the risk for colorectal cancer. Moreover, this association could be strengthened by cigarette smoking and family history of cancer.

Effects of glutathione-S-transferase polymorphisms on the risk of breast cancer: a population-based case-control study in Pakistan

Cancer is widely accepted as one of the major health issues. Diet composition and exposure to environmental genotoxic and carcinogenic agents such as polycyclic aromatic hydrocarbons (PAHs) are among the causative factors for various types of cancers, including breast cancer. Low penetrance genes including glutathione S transferases (GST) in association with environmental factors can contribute greatly in the development of breast cancer. We were interested to investigate the association of the polymorphisms of GSTM1, GSTT1, GSTP1 and GSTO2 with the risk of breast cancer in the Pakistani population. One hundred women visiting the Department of Radiology and Oncology, Nishter Hospital, Multan with pathologically confirmed breast cancer, and 100 healthy volunteers from central Pakistan were enrolled in the present study. The strength of the association of various factors with breast cancer was measured by calculating odd ratios (ORs) which were determined by logistic regression. All P values cited are two-sided; differences resulting in a P value of less or equal to 0.05 were declared statistically significant. The Hardy Weinberg equilibrium was tested for the genotype proportions in the control group, as a measure of quality control. Those aged 36-45, in menopause or with a history of cancer in the family had a significantly higher prevalence of breast cancer compared with controls. The frequency of GSTM1 and GSTT1 was similar in both control and patients suggesting no association with the risk of cancer development, however GSTM1 and GSTT1 were significantly linked with the risk of breast cancer in smokers and in women with a history of breast cancer in the family respectively. Similarly women homozygous for GSTP1 or GSTO2 and with a history of breast cancer, or in menopause, were at greater risk of breast cancer than wild type or heterozygotes. Our data suggest that genetic differences in some GST genes may be linked with an increased susceptibility to breast cancer. Furthermore it also gives an insight into the interaction between the GST polymorphisms and pre-menopausal diagnosis of breast cancer.

Predictive potential of glutathione S-transferase polymorphisms for prognosis of osteosarcoma patients on chemotherapy

OBJECTIVE

To evaluate the predictive value of glutathione S-transferase (GST) gene polymorphisms for the prognosis of osteosarcoma patients receiving chemotherapy.

METHODS

A total of 159 patients were included in our study between January 2005 and December 2007., with follow-up until January 2012. Genotyping was based upon the duplex polymerase-chain-reaction with the PCR-CTPP method.

RESULTS

At the time of diagnosis, 15.4% of the patients presented with metastasis, while 22.3% developed metastasis during follow-up. At the time of final analysis on January 2012, the median follow-up was 45.5 months. Patients with null GSTM1 and GSTT1 had a higher event free survival rate than non-null genotype, but no significant association was found between the two genotypes and prognosis of osteosarcoma. Individuals with GSTP1 Val/Val genotype tended to live shorter than with the IIe/IIe genotype, and we found a significantly higher risk of death from osteosarcoma (adjusted HR=2.35, 95% CI=1.13-4.85).

CONCLUSION

The GSTP1 gene polymorphism may have an important role in the prognosis of osteosarcoma patients with chemotherapy. Further analyses with larger samples and more genes encoding metabolizing and DNA repair enzymes are warranted.

Association of GST genetic polymorphisms with the susceptibility to hepatocellular carcinoma (HCC) in Chinese population evaluated by an updated systematic meta-analysis

Background

Due to the possible involvement of Glutathione S-transferase Mu-1 (GSTM1) and Glutathione S-transferase theta-1 (GSTT1) in the detoxification of environmental carcinogens, environmental toxins, and oxidative stress products, genetic polymorphisms of these two genes may play important roles in the susceptibility of human being to hepatocellular carcinoma. However, the existing research results are not conclusive.

Methods

A systematic literature search using databases (PubMed, Scopus, Embase, Chinese Biomedical Database, Chinese National Knowledge Infrastructure, Wanfang Data, etc.) for the eligible studies meeting the inclusion criteria including case-control studies or cohort studies is evaluated using an updated systematic meta-analysis.

Results

Significant increase in the risk of HCC in the Chinese population is found in GSTM1 null genotype (OR = 1.47, 95% CI: 1.21 to 1.79, P<0.001) and GSTT1 null genotype (OR = 1.38, 95% CI: 1.14 to 1.65, P<0.001). Analysis using the random-effects model found an increased risk of HCC in GSTM1-GSTT1 dual null population (OR = 1.79, 95% CI: 1.26 to 2.53, P<0.001). In addition, subgroup analyses showed a significant increase in the association of GST genetic polymorphisms (GSTM1, GSTT1, and GSTM1-GSTT1) with HCC in southeast and central China mainland. However, available data collected by this study fail to show an association between GST genetic polymorphisms and HCC in people from the Taiwan region (for GSTM1: OR = 0.78, 95% CI: 0.60 to 1.01, P = 0.06; for GSTT1: OR = 0.94, 95% CI: 0.78 to 1.14, P = 0.546; for GSTM1-GSTT1: OR = 1.04, 95% CI: 0.81 to 1.32, P = 0.77). Sensitivity analysis and publication bias diagnostics confirmed the reliability and stability of this meta-analysis.

Conclusions

Our results indicate that both GSTM1 and GSTT1 null genotypes are associated with an increased HCC risk in Chinese population. Peoples with dual null genotypes of GSTM1-GSTT1 are more susceptible to developing HCC. In conclusion, GST genetic polymorphisms play vital roles in the development of HCC in the Chinese population.

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.

Polymorphisms of catechol estrogens metabolism pathway genes and breast cancer risk in Mexican women

Breast cancer is associated to estrogen exposure. Allelic variants involved in estrogen metabolism might change the risk of developing this neoplasia. We examined the potential association of breast cancer risk in Mexican women with the polymorphisms CYP1A1 rs1048943, CYP1B1 rs1056836, COMT rs4680, GSTP1 rs1695, GSTT1 null and GSTM1 null which are involved in estrogen metabolism pathway. This study included 150 cases and 150 controls. A significant association was observed between, CYP1A1 rs1048943 (OR = 1.95, C.I. 1.13-3.36) and GSTP1 rs1695 (OR = 2.39, C.I. 1.24-4.24) polymorphisms with the risk of breast cancer. This risk was increased when the women were stratified according to their menopausal status. The results show that breast cancer risk significantly increases in women with 3-6 risk polymorphisms (OR = 3.75, C.I. 1.44-9.74).

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).

Evaluation of glutathione S-transferase P1 polymorphisms (Ile105Val and Ala114Val) in patients with small cell lung cancer

AIMS

Glutathione S-transferase P1 (GSTP1) plays an important role in cellular protection against oxidative stress and toxic chemicals. Polymorphisms within GSTP1 are associated with alterations in enzyme activity, which may lead to development of lung disease and cancer. In this study, we aimed to investigate the GSTP1 Ile105Val and Ala114Val polymorphisms in patients with small cell lung cancer (SCLC).

PATIENTS/METHODS

GSTP1 Ile105Val polymorphism in exon 5 and GSTP1 Ala114Val polymorphism in exon 6 were determined by using polymerase chain reaction-restriction fragment length polymorphism techniques in 89 patients with SCLC and 108 control patients with chronic obstructive pulmonary disease (COPD). Genotype frequencies and cigarette smoking intensities were compared among SCLC and COPD patients.

RESULTS

There were significantly less SCLC patients with variant exon 6 genotypes than COPD patients (7.9% vs. 20.4%, p=0.007), while the number of patients with variant exon 5 genotypes were comparable among groups. SCLC and COPD patients with variant exon 6 genotype showed trends toward exhibiting reduced cigarette consumption.

CONCLUSIONS

The variant GSTP1 exon 6 genotype might be conferring protection against SCLC development. Whether this effect is associated with exposure to cigarette smoking needs to be clarified.

Positive association of polymorphisms in estrogen biosynthesis gene, CYP19A1, and metabolism, GST, in breast cancer susceptibility

PURPOSE

This case-control study was conducted in order to evaluate the potential role of polymorphic genes encoding enzymes involved in estrogen biosynthesis (CYP19A1) and metabolism (GSTM1, GSTT1, and GSTP1), and their action in modulating individual susceptibility to breast cancer.

METHODS

Genomic DNA was extracted from blood samples of 101 patients with histological diagnosis of breast cancer and 121 healthy women. Genotyping analyses of CYP19A1 codon 39 Trp/Arg (T/C), GSTM1 and GSTT1 homozygous deletions, and GSTP1 codon 105 Ile/Val (A/G) were performed by polymerase chain reaction-based methods.

RESULTS

Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated by unconditional logistic regression. Significant statistical association of the TC/CC genotypes combined with breast cancer risk was found, with reference to TT genotype (OR=1.770; 95% CI=1.036-3.024; p=0.036). Also, CYP19A1 arginine allele in homozygosity or heterozygosity (TC/CC) was associated with a significant increased risk for breast cancer when associated to GSTM1 null genotype (OR=6.158; 95% CI=2.676-14.171; p<0.001) and GSTT1 null genotype (OR=4.870; 95% CI=2.216-10.700; p<0.001). The three-way combination of CYP19A1 TC/CC, GSTM1 null, and GSTT1 null polymorphism was related with significant increased risk for breast cancer (OR=11.429; 95% CI=3.590-36.385; p<0.001). Valine alleles compared with isoleucine alleles in codon 105 in GSTP1, in combination with CYP19A1 genotypes, were not associated with an increase of breast cancer development.

CONCLUSIONS

Our results suggest that the effect of CYP19A1 T/C polymorphism in susceptibility to breast cancer development can be modulated by the presence of GSTM1 and GSTT1, but not GSTP1.

Combined effect of CYP1B1, COMT, GSTP1, and MnSOD genotypes and risk of postmenopausal breast cancer

Objective

Estrogen plays a key role in breast cancer development and functionally relevant genetic variants within the estrogen metabolic pathway are prime candidates for a possible association with breast cancer risk. We investigated the independent and the combined effects of commonly occurring polymorphisms in four genes encoding key proteins of estrogen metabolic pathway on their potential contribution to breast cancer risk.

Methods

We studied 530 breast cancer cases and 270 controls of the same age and ethnicity participating in a case-control study of postmenopausal women. Genotyping was conducted for CYP1B1 (rs1056836), COMT (rs4680), GSTP1 (rs1695), and MnSOD (rs4880) polymorphisms by polymerase chain reaction based restriction fragment length polymorphism and TaqMan allelic discrimination method. Adjusted ORs and 95% CIs were calculated using logistic regression.

Results

None of the 4 genetic variants examined contributed to breast cancer risk individually. When the combined effects of the risk genotypes were investigated, significant associations were observed among women with two high-risk genotypes in CYP1B1 and COMT (OR, 2.0; 95% CI, 1.1 to 3.5) and two high-risk genotypes in COMT and MnSOD (OR, 2.0; 95% CI, 1.0 to 3.8), compared to those with low-risk genotypes.

Conclusion

Our results suggest that individual susceptibility to breast cancer incidence may be increased by combined effects of the high-risk genotypes in CYP1B1, COMT, and MnSOD estrogen metabolic genes.

Genetic polymorphisms of glutathione S-transferases are associated with ulcerative colitis in central China

The present study aimed to investigate the association between genetic polymorphisms of glutathione S-transferases (GSTs) and susceptibility to ulcerative colitis (UC) in central China. The prevalence of GSTM1, GSTT1, and GSTP1 gene polymorphisms were examined using polymerase chain reaction methods in 270 consecutive UC patients and 623 age- and sex-matched healthy controls. The frequencies of the GSTM1(null) and GSTT1(null) as well as GSTP1 (Val/Val) genotypes were significantly higher in UC patients than in the controls (70.74% vs. 41.74%, P = 0.0001; 64.82% vs. 47.19%, P = 0.0001; and 48.89% vs. 34.35%, P = 0.0004, respectively). When the UC patients were stratified according to clinical features, we found that the frequencies of the GSTT1(null) and GSTP1 (Val/Val) genotypes but not the GSTM1(null) genotype were significantly higher in patients with distal colitis than in extensive colitis (P = 0.0007, P = 0.001, and P = 0.271, respectively). However, these variant GST genotypes were not significantly linked to severity of the disease (P > 0.05). GST variant genotypes are strongly correlated with prevalence and extent but not with severity of UC in the Hubei Han population in central China.

Associated malignancies in patients with Waldenström's macroglobulinemia and their kin

We examined the incidence of other malignancies in 924 Waldenström's Macroglobulinemia (WM) patients and their kin. A total of 225 (24.3%) patients had ≥1 additional malignancy, with 63% predating the WM diagnosis. The most common gender-adjusted malignancies were prostate (9.4%), breast (8.0%), non-melanoma skin (7.1%), hematologic (2.8%), melanoma (2.2%), lung (1.4%) and thyroid 1.1%). Among hematologic malignancies, all 13 cases of diffuse large B-cell lymphoma and 4 cases of acute myelogenous leukemia were diagnosed after WM, and were therapy-related. Familial WM subgroup analysis showed a higher incidence of prostate cancer (P=.046) in sporadic WM patients, while patients with familial WM had a higher incidence of lung cancer (P=.0043). An increased incidence of myeloid leukemias (P<.0001) was reported among kin of familial WM patients. These data reveal specific cancer associations with WM, and provide a basis for exploratory studies aimed at delineating a common genetic basis. Additionally, these studies suggest specific cancer clustering based on familial predisposition to WM.

Glutathione S-transferase M1, T1, and P1 genotypes and breast cancer risk: a study in a Portuguese population

Glutathione S-transferases are a superfamily of multifunctional enzymes that play a key role in Phase II metabolism, detoxifying therapeutic drugs, and various carcinogens by conjugation with glutathione. We undertook a case-control study in Central-Eastern Portuguese population to evaluate the association of null genotype in GSTM1 and GSTT1 along with the polymorphism in GSTP1 (A/G) and susceptibility to breast cancer. The population sample consisted of 85 patients with histological diagnosis of breast cancer and 102 healthy women. Genomic DNA was extracted from blood samples, and genotyping analyses were performed by PCR-based methods. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated by unconditional logistic regression. We found a increased breast cancer risk associated with GSTM1 null genotype (OR = 3.597; 95% CI = 1.849-6.999; P = 0.0001) and GSTT1 (OR = 2.592; 95% CI = 1.432-4.690; P = 0.002), but the presence of valine alleles compared to isoleucine alleles in codon 105 in GSTP1 did not increase the risk of breast cancer development. The two-way combination of GSTM1 and GTTT1 null genotypes resulted in 8-fold increase for breast cancer risk (OR = 8.287; 95% CI = 3.124-21.980; P = 0.0001) and the three-way combination of GSTP1 105AA/AG and null genotypes for both GSTM1 and GSTT1 resulted in 5-fold increase for breast cancer risk (OR = 5.040; 95% CI = 1.392-18.248; P = 0.016). Our results suggest that GSTM1 and GSTT1 null genotype alone, both combined or combined with GSTP1 valine alleles, are associated with higher susceptibility to breast cancer development.

Interactions between oral contraceptive status and GSTM1 and GSTT1 deletions on insulin-like growth factor-1 (IGF-1) plasma levels in young healthy women

OBJECTIVE

Insulin-like growth factor-1 (IGF-1) is essential for the pubertal growth spurt and for normal mammary gland development. IGF-1 increases premenopausal breast cancer risk. Oral contraceptives (OCs) decrease IGF-1 in most women. The endogenous estrogens and their metabolites also influence IGF-1 levels. Glutathione S-transferases (GSTs) are involved in estrogen metabolism. We aimed to study IGF-1 levels and body size in relation to GSTM1 and GSTT1 deletions, and GSTP1*1B and current oral contraceptive (OC) status.

DESIGN

Questionnaires on reproductive factors and OC use were completed and blood samples were obtained during menstrual cycle day 18-23 in healthy women (≤40 years) from breast cancer high-risk families. IGF-1 was analyzed with radioimmunoassay. Genetic analyses were done with PCR based methods. Initially 258 women were included. After exclusion 229 women were finally included in the analyses of IGF-1 in relation to GSTM1 and GSTT1.

RESULTS

Among the 142 non-OC users, GSTM1*0/*0 or GSTT1*0/*0 alone were associated with lower IGF-1 levels while homozygous GSTM1*0/*0/GSTT1*0/*0 carriers had higher IGF-1 levels (P(interaction)=0.024). In the 87 OC users, GSTM1*0/*0 or GSTT1*0/*0 alone were associated with higher IGF-1 levels while homozygous GSTM1*0/*0/GSTT1*0/*0 carriers had lower IGF-1 levels (P(interaction)=0.010). Among all 229 women, a three-way interaction model showed an interaction between the GSTM1*0/*0/GSTT1*0/*0 genotype and OC use on IGF-1 levels (P(interaction)=0.003). GSTP1*1B was not associated with IGF-1. The GSTM1*1/GSTT1*0/*0 genotype was associated with high body weight (P=0.003) and GSTM1*0/*0/GSTT1*0/*0 was associated with early growth (P=0.003).

CONCLUSION

Both OC use and GSTT1 and GSTM1 genotypes may influence IGF-1 levels. Further studies are warranted to confirm our finding and elucidate the clinical importance.

Relationship between genetic polymorphisms of glutathione S-transferase genes and susceptibility to ulcerative colitis in Zhejiang Han population

AIM: To investigate the association between the genetic polymorphisms of glutathione S-transferases (GSTs) genes and susceptibility to ulcerative colitis (UC) in Zhejiang Han population.

METHODS: A total of 252 patients with UC were collected from the Second Affiliated Hospital of Wenzhou Medical College and other large general hospitals in Wenzhou City. The control group was composed of 578 healthy volunteers. PCR was used to examine the prevalence of GST (M1, T1, P1) gene polymorphisms in these subjects.

RESULTS: The frequencies of GSTM1 (-), GSTT1 (-) and GSTP1 (VaL/VaL) were significantly higher in UC patients than in controls (69.45% vs 46.30%, P = 0.0003; 61.51% vs 51.39%, P = 0.007; 48.81% vs 34.61%, P < 0.0001). A further observation was made on the UC patients according to the clinical features. The frequencies of GSTT1 (-) and GSTP1 (VaL/VaL) genotypes were higher in patients with distal colitis than in those with extensive colitis (P = 0.0001 and 0.001). However, the same result was not observed for GSTM1 (-) genotype (P = 0.108). In addition, the variant genotypes of GST (M1, T1, P1) were not significantly linked to the severity of the disease (all P > 0.05).

CONCLUSION: The GST (M1, T1, P1) variant genotypes are obviously correlated with the development of UC in Zhejiang Han population.

Metastasis: cancer cell's escape from oxidative stress

According to a "canonical" view, reactive oxygen species (ROS) positively contribute, in different ways, to carcinogenesis and to malignant progression of tumor cells: they drive genomic damage and genetic instability, transduce, as signaling intermediates, mitogenic and survival inputs by growth factor receptors and adhesion molecules, promote cell motility and shape the tumor microenvironment by inducing inflammation/repair and angiogenesis. Chemopreventive and tumor-inhibitory effects of endogenous, diet-derived or supplemented antioxidants largely support this notion. However, emerging lines of evidence indicates that tumor cells also need to defend themselves from oxidative damage in order to survive and successfully spread at distance. This "heresy" has recently received important impulse from studies on the role of antioxidant capacity in cancer stem cells self-renewal and resistance to therapy; additionally, the transforming activity of some oncogenes has been unexpectedly linked to their capacity to maintain elevated intracellular levels of reduced glutathione (GSH), the principal redox buffer. These studies underline the importance of cellular antioxidant capacity in metastasis, as the result of a complex cell program involving enhanced motility and a profound change in energy metabolism. The glycolytic switch (Warburg effect) observed in malignant tissues is triggered by mitochondrial oxidative damage and/or activation of redox-sensitive transcription factors, and results in an increase of cell resistance to oxidants. On the other hand, cytoskeleton rearrangement underlying cell motile and tumor-aggressive behavior use ROS as intermediates and are therefore facilitated by oxidative stress. Along this line of speculation, we suggest that metastasis represents an integrated strategy for cancer cells to avoid oxidative damage and escape excess ROS in the primary tumor site, explaning why redox signaling pathways are often up-regulated in malignancy and metastasis.

Involving stakeholders to optimize a study protocol on secondhand tobacco smoke and chronic rhinosinusitis in adults

BACKGROUND

Epidemiological evidence evaluating the association between secondhand smoke exposure and diseases of the upper airway in adults is limited by a small number of studies and a lack of established protocols. This study was designed to optimize a research protocol on secondhand tobacco smoke exposure and chronic rhinosinusitis for a future population-based case-control study in Washington County, Maryland, using a participatory research model.

METHODS

We conducted three focus groups with health professionals, community members, and research practitioners for protocol development; 10 one-on-one cognitive testings with community members for protocol refinement; and a pilot testing of the full study protocol (10 cases and 10 controls) for full evaluation of the study protocol.

RESULTS

Health professionals recommended, among other themes, enrolling patients with confirmed chronic rhinosinusitis (minimum 12-week symptom duration and objective inflammation). Community members and research practitioners discussed optimal strategies for participant recruitment and interviewing. The protocol, revised with the focus group's feedback, was further evaluated in one-on-one sessions with 10 Washington County residents (3 with chronic rhinosinusitis). In the pilot study, 10 nonsmoking chronic rhinosinusitis cases (5 clinic based and 5 community based) and their community-based age, sex, and former/never smoking-matched controls were recruited. Sinonasal symptoms scores were higher in cases than controls but similar for clinic versus community-based cases.

CONCLUSION

This protocol development framework involving stakeholders resulted in a comprehensive questionnaire that was successfully evaluated during a pilot study and is now ready to be used in population-based and clinical epidemiological studies of chronic rhinosinusitis in adults.