Genetic polymorphisms in cytochrome P450 (CYP) 1A1, CYP1A2, CYP2E1, glutathione S-transferase (GST) M1 and GSTT1 and susceptibility to prostate cancer in the Japanese population

Glutathione S-transferase theta 1 (GSTT1) deletion polymorphism and susceptibility to head and neck carcinoma: a systematic review with five analyses

Glutathione S-transferase theta 1 (GSTT1) enzyme plays a key role in the neutralization of electrophilic compounds such as carcinogens. Herein, we aimed to evaluate GSTT1 deletion polymorphism and susceptibility to head and neck carcinoma (HNC) according to 107 articles in a systematic review with five analyses. The databases of PubMed/Medline, Web of Science, Scopus, and Cochrane Library from the beginning of each database until June 21, 2023, with no restrictions to identify pertinent articles. The RevMan 5.3 software was used to calculate the effect sizes, which were displayed as the odds ratio (OR) along with a 95% confidence interval (CI). Both the publication bias and sensitivity analyses were performed using the CMA 3.0 software. A trial sequential analysis (TSA) was conducted. Of the 1966 records retrieved from four databases, 107 articles were included in the analysis. The combined analysis revealed that the pooled OR was 1.28 (95% CI: 1.14 to 1.44; p-value < 0.0001). The pooled OR was highest in mixed ethnicity. Nasopharyngeal cancer had the highest OR (1.84), followed by oral cancer (OR = 1.20), and laryngeal cancer (OR = 1.17). Studies with less than 200 samples had a higher OR compared to those with 200 or more samples. The studies with a quality score of 7 or more had a higher OR compared to those with a score of less than 7. When both age and sex are considered, while the OR of 1.42 is significant, the high heterogeneity suggests caution in interpreting these results. There is no evidence of publication bias. TSA reported that the study does not have sufficient statistical power. This comprehensive meta-analysis revealed a significant association between the GSTT1 null genotype and an increased risk of HNC, with variations based on factors such as ethnicity, cancer type, sample size, control source, and quality score.

Polymorphisms in the gene encoding CYP1A2 influence prostate cancer risk and progression

The role of the cytochrome P450 1A2 (CYP1A2) rs2472299, rs2470890 and rs11072508 polymorphisms in prostate cancer risk, disease progression and tumour development remains unclear. The potential associations of these three CYP1A2 polymorphisms and haplotypes with prostate cancer susceptibility and its clinicopathological characteristics were therefore investigated. The present case-control study consisted of 522 patients with prostate cancer and 554 healthy controls. High-resolution melting analysis was used to determine the CYP1A2 polymorphisms. No significant association in prostate cancer risk was seen for CYP1A2 rs2472299 and rs11072508. However, a significantly decreased risk of prostate cancer was found for CYP1A2 rs2470890 [odds ratio (OR), 0.67; P=0.02] in the recessive model. After analysis of the associations of clinical status and these three CYP1A2 polymorphisms, the CYP1A2 rs2470890 and rs11072508 polymorphisms showed a positive association with a higher Gleason score (rs2470890 OR, 1.36, P=0.04 in the allelic model; rs11072508 OR, 1.37, P=0.04 in the allelic model and OR, 1.60, P=0.03 in the dominant model). All three polymorphisms showed a significant positive association with pathological T stage in the additive, allelic and dominant genetic models (P<0.05). Haplotype analysis revealed that the most common haplotypes 'GTT' and 'ACC' were significantly associated with pathological T stages 3 and 4 (OR, 0.62; P=0.02 and OR, 1.54; P=0.03, respectively). A significant association was found between the 'GTT' haplotype and the Gleason score (OR, 0.71; P=0.03). In conclusion, these CYP1A2 polymorphisms and haplotypes have the potential to predict prostate cancer disease progression.

Elevated exposure to polycyclic aromatic hydrocarbons (PAHs) may trigger cancers in Pakistan: an environmental, occupational, and genetic perspective

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic compounds which are emitted through incomplete combustion of organic materials, fossil fuels, consumption of processed meat, smoked food, and from various industrial activities. High molecular mass and mobility make PAHs widespread and lethal for human health. A cellular system in human detoxifies these toxicants through specialized enzymatic machinery called xenobiotic-metabolizing (CYP450) and phase-II (GSTs) enzymes (XMEs). These metabolizing enzymes include cytochromes P450 family (CYP1, CYP2), glutathione s-transferases, and ALDHs. Gene polymorphisms in XMEs encoding genes can compromise their metabolizing capacity to detoxify ingested carcinogens (PAHs etc.) that may lead to prolong and elevated exposure to ingested toxicants and may consequently lead to cancer. Moreover, PAHs can induce cancer through reprograming XMEs' gene functions by altering their epigenetic markers. This review article discusses possible interplay between individual's gene polymorphism in XMEs' genes, their altered epigenetic markers, and exposure to PAHs in cancer susceptibility in Pakistan.

Association of CYP1A1, GSTM1 and GSTT1 gene polymorphisms with risk of prostate cancer in Algerian population

Background

Prostate cancer is the most common cancer in the world, and its etiology involves the interaction of genetic and environmental factors. Interindividual differences observed in the metabolism of xenobiotics may be due to polymorphisms of genes encoding the detoxification enzymes. This genetic variability seems to be associated with differences in susceptibility to certain types of cancers, including prostate cancer. Our study has been made in order to investigate a possible genetic predisposition to prostate cancer in an Algerian population, through the analysis of genetic polymorphisms of three enzymes metabolizing xenobiotics namely cytochrome P450 (CYP) 1A1, glutathione S-transferase mu 1 (GSTM1) and GST theta 1 (GSTT1).

Methods

The current case–control study included 101 prostate cancer patients and 101 healthy controls. Genotyping of CYP1A1 T3801C polymorphisms and GSTM1/GSTT-null was made, respectively, by PCR-RFLP and multiplex PCR.

Results

No significantly positive associations were found for the CYP1A1 T3801C [p = 0.71, OR = 1.23 (0.56–2.72)] and GSTM1-null [p = 0.26, OR = 1.37 (0.76–2.4)] polymorphisms and prostate cancer susceptibility. However, we detect a highly significant association between GSTT1-null genotype [p = 0.03, OR = 2.03 (1.06–3.99)], GSTM1/GSTT1-double null genotype [p = 0.027, OR = 2.6; CI (1.07–6.5)] and prostate cancer risk. Furthermore, no statistically significant differences between the studied polymorphisms and tumor parameters (the Gleason score and clinical stages of aggressiveness) at diagnosis of PCa.

Conclusions

The risk of developing prostate cancer in Algeria does not appear to be associated with CYP1A1 T3801C genotypes and GSTM1-null, but GSTT1-null and GSTM1/GSTT1-double null genotypes increased the risk of prostate cancer.

New insights of CYP1A in endogenous metabolism: a focus on single nucleotide polymorphisms and diseases

Cytochrome P450 1A (CYP1A), one of the major CYP subfamily in humans, not only metabolizes xenobiotics including clinical drugs and pollutants in the environment, but also mediates the biotransformation of important endogenous substances. In particular, some single nucleotide polymorphisms (SNPs) for CYP1A genes may affect the metabolic ability of endogenous substances, leading to some physiological or pathological changes in humans. This review first summarizes the metabolism of endogenous substances by CYP1A, and then introduces the research progress of CYP1A SNPs, especially the research related to human diseases. Finally, the relationship between SNPs and diseases is discussed. In addition, potential animal models for CYP1A gene editing are summarized. In conclusion, CYP1A plays an important role in maintaining the health in the body.

Associations of CYP1 polymorphisms with risk of prostate cancer: an updated meta-analysis

Background. The results of previous studies on the association between polymorphisms of CYP1A1 and CYP1B1 and prostate cancer (PCa) susceptibility are inconsistent. The aim of the present study was to conduct a meta-analysis in order to better estimate this association. Methods. A systematic search was carried out on PubMed, Embase, Cochrane Library, and China National Knowledge Infrastructure (CNKI) databases for relevant articles published up to 15 August 2018. Pooled odds ratios (ORs) and 95% confidence intervals were obtained using fixed-effect or random-effect models. Results. A significant association was found between the CYP1A1 rs1048943 polymorphism and PCa in the overall population (B [the minor allele] vs. A [the major allele]: OR = 1.20, 95% confidence interval (CI) = 1.04–1.39, P=0.014; AB vs. AA: OR = 1.24, 95% CI = 1.02–1.51, P=0.029; BB + AB vs. AA: OR = 1.25, 95% CI = 1.04–1.50, P=0.018) and Asian population (B vs. A: OR = 1.32, 95% CI = 1.11–1.56, P=0.001; BB vs. AA: OR = 1.81, 95% CI = 1.20–2.72, P=0.005; AB vs. AA: OR = 1.30, 95% CI = 1.03–1.64, P=0.029; BB + AB vs. AA: OR = 1.38, 95% CI = 1.11–1.73, P=0.004; BB vs. AA + AB: OR = 1.58, 95% CI = 1.08–2.01, P=0.019), but not in the Caucasian population. Moreover, we found that the rs4646903 polymorphism was associated with a significant increase in the risk of PCa in the Asian population (AB vs. AA: OR = 1.43, 95% CI = 1.13–1.80, P=0.003) and Caucasian population (BB vs. AA: OR = 2.12, 95% CI = 1.29–3.49, P=0.003). Conclusion. This meta-analysis revealed a clear association between rs1048943 and rs4646903 polymorphisms of the CYP1A1 gene but not between CYP1B1 rs10012, rs162549, rs1800440, and rs2551188 polymorphisms and the risk of PCa.

Association between NAT2, CYP1A1, and CYP1A2 genotypes, heterocyclic aromatic amines, and prostate cancer risk: a case control study in Japan

Background

Heterocyclic aromatic amines (HAAs) may confer prostate cancer risk; however, the evidence is inconclusive and the activity of HAA-metabolizing enzymes is modulated by gene variants. The purpose of our study was to determine whether there was evidence of an association between HAA intake, polymorphisms in NAT2, CYP1A1, and CYP1A2 and prostate cancer risk in Japanese men.

Methods

Secondary data analysis of an observational case control study was performed. Among 750 patients with prostate cancer and 870 healthy controls, 351 cases and 351 age-matched controls were enrolled for analysis. HAA intake was estimated using a food frequency questionnaire and genotypes were scored by TaqMan real-time PCR assay. Logistic regression analysis was conducted according to affected/control status.

Results

We found that high HAA intake was significantly associated with an increased risk of prostate cancer (odds ratio (OR), 1.90; 95% confidence interval (95% CI), 1.40–2.59). The increased risk of prostate cancer was observed among individuals with the NAT2 slow acetylator phenotype (OR, 1.65; 95% CI, 1.04–2.61), CYP1A1 GA + GG genotype (OR, 1.27; 95% CI, 1.02–1.59), and CYP1A2 CA + AA genotype (OR, 1.43; 95% CI, 1.03–2.00). In addition, CYP1A1 GA + GG genotypes were associated with increased cancer risk in low (OR, 2.05; 95% CI, 1.19–3.63), moderate (OR, 1.72; 95% CI, 1.07–2.76), and high (OR, 2.86; 95% CI, 1.83–4.47) HAA intake groups.

Conclusions

Our results suggest that high HAA intake is a risk factor of prostate cancer, and genotypes related to HAA metabolic enzymes can modulate the degree of the risk.

Association between CYP2E1 genetic polymorphisms and urinary cancer risk: a meta-analysis

Objective

Studies investigating the contribution of Cytochrome P4502E1 (CYP2E1) polymorphisms to the etiology of urinary cancer draw inconsistent conclusions. Thus, we performed a meta-analysis to evaluate the association between CYP2E1 Rsa I/Pst I and Dra I polymorphisms and urinary cancer susceptibility.

Materials and Methods

Meta-analysis based on the eligible case-control studies that assess the association of CYP2E1 Rsa I/Pst I and Dra I polymorphisms with urinary cancer was conducted. Subgroup analyses based on ethnicity and cancer type were also carried out. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated to evaluate the strength of the associations between the two polymorphisms. Funnel plot and Begg’s test were used for publication bias diagnosis.

Results

We found decreased urinary cancer risk among subjects carrying CYP2E1 RsaI/PstI c1c2 + c2c2 genotype and c2 allele (OR = 0.73, 95% CI = 0.68–0.79 and OR = 0.79, 95% CI = 0.74–0.85, respectively), with 3,301 cases and 3,786 controls from 14 studies. We also observed a significant difference in c1c2 + c2c2 vs. c1c1 and c2 vs. c1 among Asians (OR = 0.68, 95% CI = 0.60–0.78 and OR = 0.75, 95% CI = 0.66–0.85, respectively). However, the meta-analysis based on 5 eligible studies showed no significant association between CYP2E1 Dra I polymorphism and urinary cancer susceptibility in either dominant model or the allele model.

Conclusions

Our meta-analysis concluded that CYP2E1 Rsa I/Pst I polymorphism correlates with urinary cancers risk in Asian population; while CYP2E1 Dra I polymorphism might be not significantly associated with the urinary cancer risks. Large and well-designed studies are needed to confirm these results.

Identification of novel SNPs associated with risk and prognosis in patients with castration-resistant prostate cancer

AIM

Metabolism and transport play major roles in life-long exposure to endogenous and exogenous carcinogens. We therefore explored associations between polymorphisms in absorption, distribution, metabolism and elimination genes and the risk and prognosis of castration-resistant prostate cancer (CRPC).

MATERIALS & METHODS

A total of 634 genotypes were tested in 74 patients using the Affymetrix DMETv1.0 platform.

RESULTS

No relation to risk was found. Three SNPs were associated with CRPC prognosis in Caucasians: ABCB11 rs7602171G>A (p = 0.003; n = 30; hazard ratio [HR]: 0.307), GSTP1 rs1799811C>T (p = 0.001; n = 38; HR: 0.254) and SLC5A6 rs1395 (p = 0.004; n = 35; HR: 3.15). Two other polymorphisms among Caucasians were associated with interesting trends: ABCB4 rs2302387C>T (p = 0.039) and ABCC5 rs939339A>G (p = 0.018).

CONCLUSION

This exploratory study is the first to show that polymorphisms in several absorption, distribution, metabolism and elimination genes may be associated with CRPC prognosis.

Association of glutathione S-transferase T1 and M1 polymorphisms with prostate cancer susceptibility in populations of Asian descent: a meta-analysis

Background

Genetic polymorphism was hypothesized to be reason of variation in prostate cancer incidence among different racial group. Based on that published data on the association of prostate cancer susceptibility with polymorphisms in genes encoding Glutathione S-transferases (GSTs) were inconclusive, the aim of this study was to more precisely address the role of GSTs polymorphisms (especially, GSTT1 and GSTM1 deletions) on prostate cancer risk in Asian descent.

Methods

A meta-analysis including 8 articles with 711 cases and 1122 controls for GSTT1 and 1098 cases and 1588 controls for GSTM1 was performed.

Results

Significantly increased prostate cancer risk was found among subjects carrying GSTM1 null genotype (odds ratio (OR) = 1.403; 95% confidence interval (CI) = 1.088 – 1.808) but not among subjects carrying GSTT1 deletion genotype (OR = 0.959; 95%CI = 0.709 – 1.297). When stratified by country, the null genotype of GSTT1 neither increased nor decreased prostate cancer risk significantly in China (OR = 1.355; 95%CI = 0.895 – 2.049), Japan (OR = 0.812; 95%CI = 0.545 – 1.211), and Korea (OR = 1.056; 95%CI = 0.727 – 1.534). While significant association of elevated prostate cancer risk with GSTM1 deletion were found in China (OR = 1.665; 95%CI = 1.324 – .094) and Korea (OR = 1.914; 95%CI = 1.311 – 2.793) but not in Japan (OR = 0.980; 95%CI = 0.726 – 1.321).

Conclusion

In summary, this meta-analysis suggested that the null genotype of GSTM1 rather than GSTT1 may be involved in the etiology of prostate cancer in Asian population.

GSTT1 Null Genotype Significantly Increases the Susceptibility to Urinary System Cancer: Evidences from 63,876 Subjects

GSTT1 gene plays an important role in detoxification and clearance of reactive oxygen species(ROS). A null variant in this gene has been demonstrated to confer cancer susceptibility. Although many studies have demonstrated the association between GSTT1 null polymorphism and urinary system cancer susceptibility, several publications reported opposite conclusions. For better understanding the effects of this polymorphism on the risk of urinary system cancer, a updated meta-analysis was performed with a total of 26,666 cases and 37,210 controls extracted from 117 studies, by following the latest meta-analysis guidelines (PRISMA). The results suggested that the GSTT1 null genotype was significantly associated with an increased risk of urinary system cancer (OR=1.13, 95%CI=1.05-1.22). Furthermore, stratified analyses by the type of cancer, ethnicity, source of control and quality score presented a significantly increased risk associated with GSTT1 null genotype in bladder and prostate cancer subgroup, Caucasians and Indians subgroup, population-based(PB) subgroup, medium quality and low quality subgroup. Overall, our meta-analysis suggested that GSTT1 null genotype is a potential cancer susceptibility variant. Well-designed and large-cohort studies are needed to confirm the association between GSTT1 null genotype and urinary system cancer risk.

GSTM1 Gene Polymorphism is Implicated in Increased Susceptibility to Prostate Cancer in Caucasians and Asians

Published reports on the relationship between GSTM1 gene polymorphisms and prostate cancer risk are heterogeneous in their conclusions, and the significance of these polymorphisms is still debated. This meta-analysis was performed to attempt to combine comparable studies, thereby increasing sample size and statistical significance in order to obtain a better evaluation of the association between GSTM1 polymorphisms and prostate cancer risk. The association investigations were identified from PubMed, Cochrane Library, and China Biological Medicine Database on March 1, 2014. Forty-three reports were recruited into this meta-analysis that contained data from 6741 patients and 9053 controls. There was a marked association between the GSTM1 null genotype and prostate cancer risk in the overall population (odds ratio = 1.39, 95% confidence interval: 1.21-1.60, P <00001), caucasians (odds ratio = 1.48, 95% confidence interval: 1.23-1.79, P <0001) and Asians (odds ratio = 1.62, 95% confidence interval: 1.16-2.27, P = .005). However, the GSTM1 null genotype was not associated with prostate cancer risk in Africans (odds ratio = 0.77, 95% confidence interval: 0.53-1.13, P = 0.19) and African Americans (odds ratio = 1.00, 95% confidence interval: 0.69-1.45, P = 0.99). In conclusion, GSTM1 null genotype was a risk factor to predict the prostate cancer risk in the overall population, Caucasians, and Asians. Although compelling, limitations inherent to meta-analysis, study design of the individual studies, and most importantly, possible gene-gene and gene-environment interactions, as well as the potential involvement of glutathione S-transferases in multiple cellular processes make drawing definite conclusions difficult.

Cytochrome P450 in Cancer Susceptibility and Treatment

Cytochrome 450 (CYP450) designates a group of enzymes abundant in smooth endoplasmic reticulum of hepatocytes and epithelial cells of small intestines. The main function of CYP450 is oxidative catalysis of various endogenous and exogenous substances. CYP450 are implicated in phase I metabolism of 80% of drugs currently in use, including anticancer drugs. They are also involved in synthesis of various hormones and influence hormone-related cancers. CYP450 genes are highly polymorphic and their variants play an important role in cancer risk and treatment. Association studies and meta-analyses have been performed to decipher the role of CYP450 polymorphisms in cancer susceptibility. Cancer treatment involves multimodal therapies and evaluation of CYP450 polymorphisms is necessary for pharmacogenetic assessment of anticancer therapy outcomes. In addition, CYP450 inhibitors are being evaluated for improved pharmacokinetics and oral formulation of several anticancer drugs.

The PCA3 test for guiding repeat biopsy of prostate cancer and its cut-off score: a systematic review and meta-analysis

The specificity of prostate-specific antigen (PSA) for early intervention in repeat biopsy is unsatisfactory. Prostate cancer antigen 3 (PCA3) may be more accurate in outcome prediction than other methods for the early detection of prostate cancer (PCa). However, the results were inconsistent in repeated biopsies. Therefore, we performed a systematic review and meta-analysis to evaluate the role of PCA3 in outcome prediction. A systematic bibliographic search was conducted for articles published before April 2013, using PubMed, Medline, Web of Science, Embase and other databases from health technology assessment agencies. The quality of the studies was assessed on the basis of QUADAS criteria. Eleven studies of diagnostic tests with moderate to high quality were selected. A meta-analysis was carried out to synthesize the results. The results of the meta-analyses were heterogeneous among studies. We performed a subgroup analysis (with or without inclusion of high-grade prostatic intraepithelial neoplasia (HGPIN) and atypical small acinar proliferation (ASAP)). Using a PCA3 cutoff of 20 or 35, in the two sub-groups, the global sensitivity values were 0.93 or 0.80 and 0.79 or 0.75, specificities were 0.65 or 0.44 and 0.78 or 0.70, positive likelihood ratios were 1.86 or 1.58 and 2.49 or 1.78, negative likelihood ratios were 0.81 or 0.43 and 0.91 or 0.82 and diagnostic odd ratios (ORs) were 5.73 or 3.45 and 7.13 or 4.11, respectively. The areas under the curve (AUCs) of the summary receiver operating characteristic curve were 0.85 or 0.72 and 0.81 or 0.69, respectively. PCA3 can be used for repeat biopsy of the prostate to improve accuracy of PCa detection. Unnecessary biopsies can be avoided by using a PCa cutoff score of 20.

Tobacco smoking, polymorphisms in carcinogen metabolism enzyme genes, and risk of localized and advanced prostate cancer: results from the California Collaborative Prostate Cancer Study

The relationship between tobacco smoking and prostate cancer (PCa) remains inconclusive. This study examined the association between tobacco smoking and PCa risk taking into account polymorphisms in carcinogen metabolism enzyme genes as possible effect modifiers (9 polymorphisms and 1 predicted phenotype from metabolism enzyme genes). The study included cases (n = 761 localized; n = 1199 advanced) and controls (n = 1139) from the multiethnic California Collaborative Case-Control Study of Prostate Cancer. Multivariable conditional logistic regression was performed to evaluate the association between tobacco smoking variables and risk of localized and advanced PCa risk. Being a former smoker, regardless of time of quit smoking, was associated with an increased risk of localized PCa (odds ratio [OR] = 1.3; 95% confidence interval [CI] = 1.0-1.6). Among non-Hispanic Whites, ever smoking was associated with an increased risk of localized PCa (OR = 1.5; 95% CI = 1.1-2.1), whereas current smoking was associated with risk of advanced PCa (OR = 1.4; 95% CI = 1.0-1.9). However, no associations were observed between smoking intensity, duration or pack-year variables, and advanced PCa. No statistically significant trends were seen among Hispanics or African-Americans. The relationship between smoking status and PCa risk was modified by the CYP1A2 rs7662551 polymorphism (P-interaction = 0.008). In conclusion, tobacco smoking was associated with risk of PCa, primarily localized disease among non-Hispanic Whites. This association was modified by a genetic variant in CYP1A2, thus supporting a role for tobacco carcinogens in PCa risk.

GSTT1 polymorphism and the risk of developing prostate cancer

A possible association between glutathione S-transferase theta 1 gene (GSTT1) polymorphism and the risk of developing prostate cancer is currently hotly debated, but evidence from various epidemiologic studies remains unclear. This investigation was performed to assess whether an association between GSTT1 polymorphism and prostate cancer risk exists by using meta-analysis to combine comparable studies, thereby increasing sample size and statistical significance, as well as to identify patterns in various studies. The association reports were identified from the PubMed database and the Cochrane Library on March 1, 2013, and data from eligible studies (from 1999-2012) were synthesized. Thirty-eight reports were included in this meta-analysis on the association of the null genotype of GSTT1 with prostate cancer risk. No solid association between the GSTT1 null genotype and prostate cancer risk could be established for the overall population (odds ratio = 1.11, 95% confidence interval: 0.97, 1.27; P = 0.13). However, the GSTT1 null genotype was distinctly associated with prostate cancer risk in Caucasians (odds ratio = 1.24, 95% confidence interval: 1.03, 1.48, P = 0.02). In conclusion, the GSTT1 null genotype is associated with prostate cancer risk in Caucasians, but not in the overall population.

CYP1A1 and CYP2E1 genotypes and risk of esophageal squamous cell carcinoma in a high-incidence region, Kashmir

The study analyzed the relationship between genetic polymorphisms of phase I xenobiotic metabolizing enzymes, cytochromes P450 (CYP) 1A1 and CYP2E1 and esophageal squamous cell carcinoma (ESCC) in Kashmir, India. The different genotypes of CYP1A1 and CYP2E1 were analyzed by polymerase chain reaction and restriction fragment length polymorphism in 526 ESCC cases and equal number of matched controls. Conditional logistic regression models were used to assess the association of various genotypes with ESCC, gene-gene, and gene-environment interactions. High risk of ESCC was found in participants who carried CYP1A1 Val/Val genotype (OR=2.87; 95 % CI=1.00-8.44) and the risk increased in such individuals when c1/c1 of CYP2E1 genotype was also present (OR=5.68; 95 % CI=1.09-29.52). Risk due to CYP1A1 Val/Val genotype was further enhanced (OR=8.55; 95 % CI=1.86-42.20) when the analysis was limited to ever smokers. Participants who carried CYP2E1 c1/c2 genotype showed an inverse relation (OR=0.27; 95 % CI=0.17-0.43) with ESCC. The inverse association of CYP2E1 c1/c2 genotype was retained when CYP1A1 Ile/Ile was also present (OR=0.18; 95 % CI=0.09-0.32), as well as when analysis was limited to ever smokers (OR=0.45; 95 % CI=0.23-0.90). Significant interaction was found between CYP1A1 (Val/Val) and CYP2E1 (c1/c1) genotypes (OR=1.30; 95 % CI=1.12-1.51; P=0.001) and between CYP1A1 (Val/Val) and smoking (OR=1.31; 95 % CI=1.01-1.69; P=0.043). The study suggests CYP1A1 Val/Val and CYP2E1 c1/c1 genotypes are significantly associated with ESCC risk.

Alternative genotyping method ofGSTT1null/present polymorphism

Glutathione S-transferase (GST) theta is an enzyme to detoxify xenobiotic compounds. The gene GSTT1 has a null/present polymorphism in one of the targets for cancer susceptibility research. The polymorphism is classified into two types: present type with at least one present allele (heterozygote and homozygote) and null type without a present allele. Although one report showed a method to distinguish the heterozygote from the present homozygote, its use has been limited possibly owing to the difficulty of successful genotyping of long DNA sequences (1460 base pairs). This article reports an alternative method utilizing typical PCR primers specific to the null allele (566 base pairs) and the present allele (458 base pairs). All samples of the GSTT1 null genotype processed by the present PCR method (n = 331), were correctly classified as the null genotype by a conventional method, and the samples of heterozygous (n = 364) or present homozygous (n = 108) genotype as the present genotype; this indicates that it is appropriate for future research to utilize three genotypes of the GSTT1 null/present polymorphism.

Toxicogenetic profile and cancer risk in Lebanese

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

Contribution of CYP2E1 polymorphism to aging in the mechanical workshop workers

Aging is attributed to both genetic and environmental factors. Occupational exposure is one of the environmental factors with potential genotoxic effects. Researchers try to determine factors involved in genetic damages at hazards exposure that could accelerate aging. Cytochrome P450 2E1 (CYP2E1) gene contributes in activation and detoxification of the environmental hazards. This polymorphism plays an important role in susceptibility of inter-individuals to DNA damage at the occupational exposure. The current study evaluated the possible influence of this gene polymorphism in aging by genomic damages through the biomarkers alterations of micronuclei (MN), comet tail length and telomere length shortening at the exposure. In this study, buccal cells were collected from the oral cavity of exposed workers and non-exposed controls. The CYP2E1 genotypes were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The wild genotype significantly affected MN frequency (p = 0.007) and relative telomere length (p = 0.047) in the older group of workers. It was concluded that the interaction of gene polymorphism and exposure enhances DNA damage and accelerates aging consequently.

GSTT1 and GSTM1 polymorphisms and prostate cancer risk in Asians: a systematic review and meta-analysis

Glutathione S-transferases (GSTs) enzymes are involved in conjugation of electrophilic compounds to glutathione, and glutathione S-transferase T 1 (GSTT1) and glutathione S-transferase M 1 (GSTM1) polymorphisms have been implicated as risk factors for prostate cancer. We conducted a systematic review and meta-analysis to define the effect of GSTM1 and GSTT1 null genotypes on prostate cancer risk in Asians. We searched the PubMed and Wanfang Medical databases to identify published case-control studies investigating the associations of GSTM1 and GSTT1 null genotypes with risk of prostate cancer in Asians. Heterogeneity was assessed using Cochran's Q statistic and odds ratios (OR) with corresponding 95 % confidence intervals (95 % CI) from individual studies were pooled using fixed or random effects models according to the heterogeneity. There were 18 studies (2,046 cases, 2,876 controls) on GSTM1 polymorphism, 15 studies (1,677 cases, 2,431 controls) on GSTT1 polymorphism, and 6 studies (675 cases, 853 controls) on GSTM1/GSTT1 interaction analysis. Overall, GSTM1 null genotype was significantly associated with increased risk of prostate cancer in Asians (random effects OR 1.80, 95 % CI 1.48-2.18, P < 0.001), and GSTT1 null genotype was also significantly associated with increased risk of prostate cancer in Asians (random effects OR 1.40, 95 % CI 1.10-1.80, P < 0.001). In addition, the GSTM1/GSTT dual null genotype was associated with higher risk of prostate cancer in Asians (random effects OR 2.14, 95 % CI 1.59-2.89, P = 0.007). In conclusion, GSTM1 and GSTT1 null genotypes are associated with increased risk of prostate cancer in Asians, and GSTM1 and GSTT1 null genotypes are risk factors for the development of prostate cancer.

Comparative study and meta-analysis of meta-analysis studies for the correlation of genomic markers with early cancer detection

A large number of common disorders, including cancer, have complex genetic traits, with multiple genetic and environmental components contributing to susceptibility. A literature search revealed that even among several meta-analyses, there were ambiguous results and conclusions. In the current study, we conducted a thorough meta-analysis gathering the published meta-analysis studies previously reported to correlate any random effect or predictive value of genome variations in certain genes for various types of cancer. The overall analysis was initially aimed to result in associations (1) among genes which when mutated lead to different types of cancer (e.g. common metabolic pathways) and (2) between groups of genes and types of cancer. We have meta-analysed 150 meta-analysis articles which included 4,474 studies, 2,452,510 cases and 3,091,626 controls (5,544,136 individuals in total) including various racial groups and other population groups (native Americans, Latinos, Aborigines, etc.). Our results were not only consistent with previously published literature but also depicted novel correlations of genes with new cancer types. Our analysis revealed a total of 17 gene-disease pairs that are affected and generated gene/disease clusters, many of which proved to be independent of the criteria used, which suggests that these clusters are biologically meaningful.

CYP1A1 MspI polymorphism is associated with prostate cancer susceptibility: evidence from a meta-analysis

Cytochrome P450 1A1 (CYP1A1), an important phase I xenobiotic metabolizing enzyme, is responsible for metabolizing numerous carcinogens, particularly polycyclic aromatic hydrocarbons. The genetic polymorphism of CYP1A1 at the site of MspI (CYP1A1 MspI) has been implicated in prostate cancer risk, but the results of individual studies remain conflicting and inconclusive. The aim of this meta-analysis was to investigate the association of CYP1A1 MspI polymorphism with prostate cancer risk more precisely. We performed a comprehensive search of the PubMed, Embase, Web of Science, and China National Knowledge Infrastructure databases from their inception up to September 20, 2012 for relevant publications. The pooled odds ratios with the corresponding 95% confidence intervals (95% CIs) were calculated to assess the association of CYP1A1 MspI polymorphism with prostate cancer risk. In addition, stratified analyses by ethnicity and sensitivity analyses were conducted for further estimation. Sixteen eligible publications with 6,411 subjects were finally included into the meta-analysis after checking the retrieved papers. Overall, meta-analysis of total studies suggested that individuals carrying the TC genotype and a combined C genotype (CC + TC) were more susceptible to prostate cancer (OR(TC vs. TT) = 1.33, 95% CI 1.10-1.61, P(OR) = 0.004; OR(CC+TC vs. TT) = 1.27, 95% CI 1.05-1.55, P(OR) = 0.016). Stratified analysis of high quality studies also confirmed the significant association (OR(TC vs. TT) = 1.32, 95% CI 1.04-1.67, P(OR) = 0.024; OR(CC+TC vs. TT) = 1.30, 95% CI 1.02-1.66, P(OR) = 0.035). In subgroup analyses by ethnicity, a significant association between the CYP1A1 MspI polymorphism and risk of prostate cancer was found among Asians (OR(TC vs. TT) = 1.44, 95% CI 1.20-1.72, P(OR) < 0.001; OR(CC+TC vs. TT) = 1.33, 95% CI 1.12-1.58, P(OR) = 0.001), but not in Caucasians or mixed populations. The meta-analysis suggests an important role of the CYP1A1 MspI polymorphism in the risk of developing prostate cancer, especially in Asians.

Association of GSTT1 gene polymorphisms with the risk of prostate cancer: an updating meta-analysis

It has been demonstrated that the glutathione S-transferase (GST) superfamily helps remove carcinogens from the body and thus might be associated with prostate cancer risk. In recent years, GSTT1 polymorphism has been extensively studied as a potential prostate cancer risk factor; however, the results are inconsistent. To investigate the association between GSTT1 and prostate cancer, we conducted a meta-analysis of 33 studies with 6,697 prostate patients and 7,643 controls. For GSTM1 null versus present genotype, the random effects odds ratio was 0.98 (95 % confidence interval (CI) 0.83-1.16) based on a wide population. Subgroup analyses in the different ethnic groups and different controls were performed. The OR was 1.01 (95 % CI 0.86-1.19) in Caucasians, 1.01 (95 % CI 0.70-1.47) in Asians, and 0.77 (95 % CI 0.42-1.42) in Africans. The OR was 0.98 (95 % CI 0.82-1.16) in non-benign prostate hyperplasia (BPH) controls and 1.09 (95 % CI 0.66-1.79) in BPH controls. In conclusion, our present meta-analysis demonstrates that there is no association between GSTT1 polymorphism and prostate cancer, even in the sub-analysis concerning different races and control sources. The direction of further research should focus not only on the simple relationship of GSTT1 and prostate cancer but also on gene-environment interaction and distinctions of different GSTs.

Quantitative synthesis of the association between the cytochrome P450 1A1 Ile462Val polymorphism and prostate cancer risk

The association between the cytochrome P450 1A1 (CYP1A1) Ile462Val polymorphism and prostate cancer risk remains inconclusive owing to the conflicting findings from previous studies. To get a more precise estimate of the possible association, we performed the present meta-analysis. We searched the PUBMED, EMBASE, and Wanfang databases for the studies which met the inclusion criteria. The pooled odds ratio (OR) with corresponding 95 % confidence interval (95 % CI) was used to estimate the association between CYP1A1 Ile462Val polymorphism and prostate cancer risk. A total of 13 studies with 2,350 cases and 2,992 controls were included in the meta-analysis. The results indicated that there was an obvious association between CYP1A1 Ile462Val polymorphism and increased risk of prostate cancer (for Val versus Ile: OR=1.27, 95 % CI 1.13-1.43, P<0.001; for ValVal versus IleIle: OR=1.51, 95 % CI 1.14-2.01, P=0.004; for ValVal + ValIle versus IleIle: OR=1.31, 95 % CI 1.14-1.51, P<0.001; for ValVal versus IleIle + ValIle: OR=1.38, 95 % CI 1.05-1.81, P=0.020). Subgroup analyses by ethnicity suggested that CYP1A1 Ile462Val polymorphism was associated with prostate cancer risk in Asians but not in Caucasians. This meta-analysis suggests that there is an association between CYP1A1 Ile462Val polymorphism and increased risk of prostate cancer. More studies with large sample are needed to further assess the association in Caucasians.

Significant association of Glutathione S-transferase T1 null genotype with prostate cancer risk: a meta-analysis of 26,393 subjects

Background

Recent studies on the association between Glutathione S-transferase T1 (GSTT1) polymorphism and risk of prostate cancer showed inconclusive results. To clarify this possible association, we conducted a meta-analysis of published studies.

Methods

Data were collected from the following electronic databases: Pubmed, Embase, and Chinese Biomedical Database (CBM). The odds ratio (OR) and its 95% confidence interval (95%CI) was used to assess the strength of the association. We summarized the data on the association between GSTT1 null genotype and risk of prostate cancer in the overall population, and performed subgroup analyses by ethnicity, adjusted ORs, and types of controls.

Results

Ultimately, a total of 43 studies with a total of 26,393 subjects (9,934 cases and 16,459 controls) were eligible for meta-analysis. Overall, there was a significant association between GSTT1 null genotype and increased risk of prostate cancer (OR = 1.14, 95%CI 1.01–1.29, P = 0.034). Meta-analysis of adjusted ORs also showed a significant association between GSTT1 null genotype and increased risk of prostate cancer (OR = 1.34, 95%CI 1.09–1.64, P = 0.006). Similar results were found in the subgroup analyses by ethnicity and types of controls.

Conclusion

This meta-analysis demonstrates that GSTT1 null genotype is associated with prostate cancer susceptibility, and GSTT1 null genotype contributes to increased risk of prostate cancer.

Case-control study of lifetime alcohol intake and prostate cancer risk

PURPOSE

Alcohol consumption may be a modifiable risk factor for prostate cancer, but previous results have been inconsistent and limited by a lack of data on lifetime exposure and specific beverages. Furthermore, the effect of tumor stage and severity of disease on the association between alcohol and prostate cancer risk has not been fully investigated.

METHODS

We examined the relation between both current and lifetime alcohol intake and prostate cancer risk in a population-based case-control study in Alberta, Canada with 947 cases with stage T2 and higher prostate cancer diagnosed between 1997 and 2000 and frequency matched to 1,039 controls, identified through random digit dialing. Cases were classified on cancer stage and severity into 619 non-aggressive (Stage II and Gleason score <8) and 328 aggressive cases (Stage III/IV or Gleason score ≥8). In-person interviews were completed on current and lifetime history of alcohol consumption and all other prostate cancer risk factors.

RESULTS

Current alcohol intake did not increase prostate cancer risk but lifetime intake increased risk for both non-aggressive and aggressive cases, with an odds ratio of 1.78 (95 % CI 1.19-2.66) and 2.00 (95 % CI 1.19-3.36), respectively, for the highest intake quartile compared to non-drinkers with evidence for a linear trend. Associations with alcohol intake remained after exclusion of non-drinkers for non-aggressive prostate cancer cases. Only lifetime beer intake was significantly associated with increased risk, however, intakes of liquor and wine by participants were low.

CONCLUSIONS

Results support the evidence for an increased risk of prostate cancer from lifetime alcohol consumption.

Genetic polymorphisms of GSTM1, GSTT1, and GSTP1 with prostate cancer risk: a meta-analysis of 57 studies

Background and Objectives

The GSTM1, GSTT1 and GSTP1 polymorphisms might be involved in inactivation of procarcinogens that contribute to the genesis and progression of cancers. However, studies investigating the association between GSTM1, GSTT1 or GSTP1 polymorphisms and prostate cancer (PCa) risk report conflicting results, therefore, we conducted a meta-analysis to re-examine the controversy.

Methods

Published literature from PubMed, Embase, Google Scholar and China National Knowledge Infrastructure (CNKI) were searched (updated to June 2, 2012). According to our inclusion criteria, studies that observed the association between GSTM1, GSTT1 or GSTP1 polymorphisms and PCa risk were included. The principal outcome measure was the odds ratio (OR) with 95% confidence interval (CI) for the risk of PCa associated with GSTM1, GSTT1 and GSTP1 polymorphisms.

Results

Fifty-seven studies involving 11313 cases and 12934 controls were recruited. The overall OR, which was 1.2854 (95% CI = 1.1405–1.4487), revealed a significant risk of PCa and GSTM1 null genotype, and the similar results were observed when stratified by ethnicity and control source. Further, the more important is that the present study first reported the high risks of PCa for people who with dual null genotype of GSTM1 and GSTT1 (OR = 1.4353, 95% CI = 1.0345–1.9913), or who with GSTT1 null genotype and GSTP1 A131G polymorphism (OR = 1.7335, 95% CI = 1.1067–2.7152). But no association was determined between GSTT1 null genotype (OR = 1.102, 95% CI = 0.9596–1.2655) or GSTP1 A131G polymorphism (OR = 1.0845, 95% CI = 0.96–1.2251) and the PCa risk.

Conclusions

Our meta-analysis suggested that the people with GSTM1 null genotype, with dual null genotype of GSTM1 and GSTT1, or with GSTT1 null genotype and GSTP1 A131G polymorphism are associated with high risks of PCa, but no association was found between GSTT1 null genotype or GSTP1 A131G polymorphism and the risk of PCa. Further rigorous analytical studies are highly expected to confirm our conclusions and assess gene-environment interactions with PCa risk.

Frequencies of 23 functionally significant variant alleles related with metabolism of antineoplastic drugs in the chilean population: comparison with caucasian and asian populations

Cancer is a leading cause of death worldwide. The cancer incidence rate in Chile is 133.7/100,000 inhabitants and it is the second cause of death, after cardiovascular diseases. Most of the antineoplastic drugs are metabolized to be detoxified, and some of them to be activated. Genetic polymorphisms of drug-metabolizing enzymes can induce deep changes in enzyme activity, leading to individual variability in drug efficacy and/or toxicity. The present research describes the presence of genetic polymorphisms in the Chilean population, which might be useful in public health programs for personalized treatment of cancer, and compares these frequencies with those reported for Asian and Caucasian populations, as a contribution to the evaluation of ethnic differences in the response to chemotherapy. We analyzed 23 polymorphisms in a group of 253 unrelated Chilean volunteers from the general population. The results showed that CYP2A6*2, CYP2A6*3, CYP2D6*3, CYP2C19*3, and CYP3A4*17 variant alleles are virtually absent in Chileans. CYP1A1*2A allele frequency (0.37) is similar to that of Caucasians and higher than that reported for Japanese people. Allele frequencies for CYP3A5*3(0.76) and CYP2C9*3(0.04) are similar to those observed in Japanese people. CYP1A1*2C(0.32), CYP1A2*1F(0.77), CYP3A4*1B(0.06), CYP2D6*2(0.41), and MTHFR T(0.52) allele frequencies are higher than the observed either in Caucasian or in Japanese populations. Conversely, CYP2C19*2 allelic frequency (0.12), and genotype frequencies for GSTT1 null (0.11) and GSTM1 null (0.36) are lower than those observed in both populations. Finally, allele frequencies for CYP2A6*4(0.04), CYP2C8*3(0.06), CYP2C9*2(0.06), CYP2D6*4(0.12), CYP2E1*5B(0.14), CYP2E1*6(0.19), and UGT2B7*2(0.40) are intermediate in relation to those described in Caucasian and in Japanese populations, as expected according to the ethnic origin of the Chilean population. In conclusion, our findings support the idea that ethnic variability must be considered in the pharmacogenomic assessment of cancer pharmacotherapy, especially in mixed populations and for drugs with a narrow safety range.

Pregnancy, smoking and birth outcomes

This review summarizes the epidemiology and consequences of maternal smoking in pregnancy, with emphasis on the adverse effects on birth outcomes. In developed countries, approximately 15%, and in developing countries, approximately 8% of women smoke cigarettes, and adolescents and women from lower socioeconomic groups are more likely than other women to smoke while pregnant. Maternal smoking during pregnancy is the largest modifiable risk factor for intrauterine growth restriction. A meta-analysis of recent studies showed that the pooled estimate for reduction of mean birthweight was 174 g (95% confidence limits 132-220 g). Other studies confirm a weaker association between maternal smoking and preterm birth. The population attributable risk of low birthweight due to maternal smoking in the UK is estimated to be 29-39%. Tobacco smoke toxins damage the placenta and may lead to placental abruption, abortion or placenta praevia. Infants of mothers who smoke in pregnancy are at an increased risk of respiratory complications including asthma, obesity and, possibly, behavioral disorders. These effects may be dose-related, as there is good evidence that mean birthweight decrements are greater with increased numbers of cigarettes smoked during pregnancy. Cotinine is a useful indicator of tobacco smoke exposure in pregnant women and higher levels in body fluids have been related to lower birthweights. Maternal genetic polymorphisms of the cytochrome P (CYP)450 and glutathione-S-transferase (GST) subfamilies of metabolic genes influence the magnitude of the effect of nicotine exposure on birth outcomes through their influence on nicotine metabolism. Greatly increased risk of cigarette smoke-induced diseases, including low birthweight, has been found in individuals with susceptible genotypes. Interventions to control maternal smoking are also considered.

Association of GSTM1 null allele with prostate cancer risk: evidence from 36 case-control studies

BACKGROUND

Glutathione S-transferase M1 (GSTM1) is thought to be involved in detoxifying several carcinogens and may play a vital role in tumorigenesis. Numerous studies have evaluated the association between GSTM1 null/present polymorphism and risk of prostate cancer (PCa). However, the results remain inconsistent. To derive a more precise estimation, we performed a meta-analysis.

METHODOLOGY/PRINCIPAL FINDINGS

A comprehensive search was conducted to identify all eligible case-control studies. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. The overall association was significant (OR = 1.28, 95% CI: 1.11-1.48, P = 0.001). Moreover, subgroup analyses showed GSTM1 null genotype significantly associated with PCa risk among Asians (OR = 1.35, 95% CI: 1.03-1.78, P = 0.03) but not among Caucasians (OR = 1.12, 95% CI: 0.96-1.31, P = 0.16). In addition, we did not find that smoking modified the genotype effect on the risk of PCa.

CONCLUSIONS/SIGNIFICANCE

The present meta-analysis suggested that GSTM1 null allele was a low-penetrant risk factor for PCa among Asians.

Partition decoupling for multi-gene analysis of gene expression profiling data

Background

Multi-gene interactions likely play an important role in the development of complex phenotypes, and relationships between interacting genes pose a challenging statistical problem in microarray analysis, since the genes involved in these interactions may not exhibit marginal differential expression. As a result, it is necessary to develop tools that can identify sets of interacting genes that discriminate phenotypes without requiring that the classification boundary between phenotypes be convex.

Results

We describe an extension and application of a new unsupervised statistical learning technique, known as the Partition Decoupling Method (PDM), to gene expression microarray data. This method may be used to classify samples based on multi-gene expression patterns and to identify pathways associated with phenotype, without relying upon the differential expression of individual genes. The PDM uses iterated spectral clustering and scrubbing steps, revealing at each iteration progressively finer structure in the geometry of the data. Because spectral clustering has the ability to discern clusters that are not linearly separable, it is able to articulate relationships between samples that would be missed by distance- and tree-based classifiers. After projecting the data onto the cluster centroids and computing the residuals ("scrubbing"), one can repeat the spectral clustering, revealing clusters that were not discernible in the first layer. These iterations, each of which provide a partition of the data that is decoupled from the others, are carried forward until the structure in the residuals is indistinguishable from noise, preventing over-fitting. We describe the PDM in detail and apply it to three publicly available cancer gene expression data sets. By applying the PDM on a pathway-by-pathway basis and identifying those pathways that permit unsupervised clustering of samples that match known sample characteristics, we show how the PDM may be used to find sets of mechanistically-related genes that may play a role in disease. An R package to carry out the PDM is available for download.

Conclusions

We show that the PDM is a useful tool for the analysis of gene expression data from complex diseases, where phenotypes are not linearly separable and multi-gene effects are likely to play a role. Our results demonstrate that the PDM is able to distinguish cell types and treatments with higher accuracy than is obtained through other approaches, and that the Pathway-PDM application is a valuable technique for identifying disease-associated pathways.

Population differences in major functional polymorphisms of pharmacokinetics/pharmacodynamics-related genes in Eastern Asians and Europeans: implications in the clinical trials for novel drug development

Drug lag, recently discussed extensively in Japan, can be divided into two phases: clinical development time and application review time. The former factor is still an important problem that might be improved by promoting multi-regional clinical trials and considering the results from other similar populations with Japanese, such as Koreans and Chinese. In this review, we compare the allelic or genotype frequencies of 30 relatively common functional alleles mainly between Eastern Asians and Europeans as well as among 3 major populations in Eastern Asian countries, Japan, Korea, and China, in 12 pharmacokinetics (PK)/pharmacodynamics (PD)-related genes; CYP2C9 (*2 and *3), CYP2C19 (*2, *3 and *17), 13 CYP2D6 haplotypes including *4, *5 and *10, CYP3A5 (*3), UGT1A1 (*28 and *6), NAT2 (*5, *6 and *7), GSTM1 and GSTT1 null genotypes, SLCO1B1 521T>C, ABCG2 421C>A, and HLA-A*31:01 and HLA-B*58:01. In this review, differences in allele frequencies (AFs) or genotype frequencies (GFs) less than 0.1 (in the cases of highest AF (GF) ≥0.1) or less than 0.05 (in the cases of lowest AF (GF) <0.1) were regarded as similar. Between Eastern Asians and Europeans, AFs (or GFs) are regarded as being different for many alleles such as CYP2C9 (*2), CYP2C19 (*2, *3 and *17), CYP2D6 (*4 and *10), CYP3A5 (*3), UGT1A1 (*28 and *6), NAT2 (*5*7), GSTT1 null and ABCG2 421C>A. Among the 3 Eastern Asian populations, however, only AFs of CYP2C19*3, CYP2D6*10, HLA-A*31:01 and HLA-B*58:01 are regarded as dissimilar. For CYP2C19*3, the total functional impact on CYP2C19 could be small if the frequencies of the two null alleles CYP2C19*2 and *3 are combined. Regarding CYP2D6*10, frequency difference over 0.1 is observed only between Japanese and Chinese (0.147). Although environmental factors should be considered for PK/PD differences, we could propose that among Japan, Korea, and China, genetic differences are very small for the analyzed common PK-related gene polymorphisms. On the other hand, AFs of the two HLA alleles important for cutaneous adverse drug reactions are diverse even among Eastern Asians and thus should be taken into account.

Relationship between the Glutathione-S-Transferase P1, M1, and T1 Genotypes and Prostate Cancer Risk in Korean Subjects

Purpose

The glutathione-S-transferase (GST)P1, GSTM1, and GSTT1 genotypes have been associated with an increased risk of prostate, bladder, and lung cancers. The aim of this study was to investigate the association between the GSTP1, GSTM1, and GSTT1 genotypes and the risk of prostate cancer in Korean men.

Materials and Methods

The study group consisted of 166 patients with histologically confirmed prostate cancer. The control group consisted of 327 healthy, cancer-free individuals. The diagnosis of prostate cancer was made by transrectal ultrasound-guided biopsy. Patients with prostatic adenocarcinoma were divided into organ-confined (≤pT2) and non-organ-confined (≥pT3) subgroups. The histological grades were subdivided according to the Gleason score. The GSTP1, GSTM1, and GSTT1 genotypes were determined by using polymerase chain reaction-based methods. The relationship among GSTP1, GSTM1, and GSTT1 polymorphisms and prostate cancer in a case-control study was investigated.

Results

The frequency of the GSTM1 null genotype in the prostate cancer group (54.2%) was higher than in the control group (odds ratio=1.53, 95% confidence interval=1.20-1.96). The comparison of the GSTP1, GSTM1, and GSTT1 genotypes and cancer prognostic factors, such as staging and grading, showed no statistical significance.

Conclusions

An increased risk for prostate cancer may be associated with the GSTM1 null genotype in Korean men, but no association was found with the GSTT1 or GSTP1 genotypes.

Are GSTM1, GSTT1 and CAG repeat length of androgen receptor gene polymorphisms associated with risk of prostate cancer in Iranian patients?

We conducted this study to investigate whether CAG repeat length in androgen receptor gene and GSTM1 and GSTT1 polymorphisms influence prostate cancer risk in Iranian newly diagnosed cancer patients compared to age-matched BPH group and healthy individuals. DNA from 110 pathologically-confirmed prostate cancer patients, 99 age-matched men with Benign Prostatic Hyperplasia (BPH) and 100 healthy individuals were extracted and amplified by polymerase chain reaction (PCR). PCR products were examined by electrophoresis and sequencing. The mean number of CAG repeat in prostate cancer patients was significantly smaller than normal (19.9 vs 22.8; p < 0.0001) and BPH groups (19.9 vs 21.9; P < 0.0001) The mean difference between normal individuals and BPH group was also significant (21.9 vs. 22.8; P = 0.003). Presence of GSTM1 null genotype were significantly higher in cancer and BPH group vs. normal individuals (both P values < 0.0001). there was not seen association between GSTT1 null or positive genotype with cancer risk, but analysis of GSTM1 null and GSTT1 positive in combination was statistically associated with Prostate cancer risk (OR = 8.4, 95% CI 1.53-46.73). Our results showed that CAG repeat polymorphism in AR gene may act as a risk modifier and GSTM1 null genotypes also may be contributed to prostate cancer susceptibility in Iranian patients.

A genetic polymorphism of CYP2C19 is associated with susceptibility to biliary tract cancer

PURPOSE

Cytochrome P450 2C19 (CYP2C19) is clinically important for the metabolism of many therapeutic drugs. CYP2C19 has two main point mutation sites leading to low metabolic capacity. Several CYP enzymes are also important for the metabolism of chemical carcinogens, and several studies have reported associations between CYP polymorphism and cancer susceptibility. Speculating on a potential association between CYP2C19 polymorphism and cancer susceptibility, we conducted this study in two phases. Cell lines of various gastroenterological cancers were screened in the first phase. A clinical investigation was then conducted to confirm the association with the candidate cancer in the second phase.

METHODS

Genetic polymorphism of CYP2C19 was investigated in a total of 114 cell lines of five gastroenterological cancers. Based on this screening investigation suggesting an association with biliary tract cancer, we conducted a related study by recruiting 65 patients with biliary tract cancer and 566 patients with benign diseases as controls.

RESULTS

Among the 114 cell lines investigated, biliary tract cancer was suggested to be most strongly associated with poor metabolizers of CYP2C19. Among 65 patients with biliary tract cancer, 18 (28%) were poor metabolizers of CYP2C19, whereas 87 (15%) of 566 control patients were poor metabolizers. The age- and gender-adjusted odds ratios for intermediate and poor metabolizers regarding the risk of biliary tract cancer were 1.5 (95% CI: 0.8-3.0, P = 0.17) and 2.7 (1.3-5.9, P = 0.006) compared to extensive metabolizers.

CONCLUSIONS

A genetic polymorphism of CYP2C19 is associated with susceptibility to biliary tract cancer.

Inhibition of 17β-estradiol activation by CYP1A1: genotype- and regioselective inhibition by St. John's Wort and several natural polyphenols

Several epidemiological studies associate certain CYP1A1 genotypes, alone or in combination, with an increased risk of estrogen-related cancers. Previously we demonstrated that metabolic activation of estrogens by CYP1A1 is a genotype-dependent reaction with the CYP1A1.2 (Ile462Val) variant being the most efficient catalyst (Kisselev et al.). To answer the question whether genotype-dependent inhibition of activation of estrogens by CYP1A1 could also contribute, we studied the inhibition of hydroxylation activity of the most common allelic variants of human CYP1A1 towards 17β-estradiol. We expressed and purified CYP1A1.1 (wild-type), CYP1A1.2 (Ile462Val), and CYP1A1.4 (Thr461Asn) and performed inhibition assays by natural polyphenols of our diet and drugs of NADPH-dependent estradiol hydroxylation in reconstituted CYP1A1 systems. From the polyphenols studied, a St. John's Wort (Hypericum perforatum) extract, some of its main single constituents hypericin, pseudohypericin, and quercetin, as well as the flavonols kaempferol, myricetin and the phytoestrogens resveratrol and tetramethyl-stilbene exhibited strong inhibition. For the St. John's Wort extract and its single constituents hypericin, pseudohypericin, and quercetin, inhibition exhibited a remarkable dependency on the CYP1A1 genotype. Whereas (wild-type) CYP1A1.1 was most inhibited by the whole crude extract, the variant CYP1A1.2 (Ile462Val) was significantly stronger inhibited by the constituents in its pure form: IC₅₀ values for 2-hydroxylation was more than two times lower compared with the wild-type enzyme and the variant CYP1A1.4 (Thr461Asn). Besides this, the inhibition exhibited a remarkable regioselectivity. The data suggest that risk of estrogen-mediated diseases might be not only influenced by CYP1A1 genotype-dependent activation but also its inhibition by natural polyphenols of our diet and drugs.

Polymorphisms of glutathione-S-transferase M1 and T1 and prostate cancer risk in a Tunisian population

Several genes involved in the metabolism of carcinogenesis have been found to be polymorphic in the human population, and specific alleles are associated with increase risk of cancer of various sites. This study is focused on the polymorphic enzymes glutathione-S-transferase M1 (GSTM1) and T1 (GSTT1) that involved in the detoxification of many xenobiotics involved in the etiology of prostate cancer.

OBJECTIVE

To evaluate whether GSTM1 and/or GSTT1 contribute to prostate cancer (CaP) etiology, we studied 110 incident CaP cases and 122 controls.

RESULTS

The probability of having CaP was increased in men who had homozygous deleted (non-functional) genotypes at GSTT1 (OR=2.17; 95% CI=1-3.79) but not GSTM1 (OR=0.89; 95% CI=0.66-1.88). Hence, individuals lacking the GSTT1 gene are at approximately twofold higher risk of developing prostate cancer in comparison with individuals with at least one active allele in the GSTT1 locus.

CONCLUSION

These results suggest that GSTT1 is associated with CaP risk. The effect of smoking associated with the GSTT10/0 genotype was not found to affect the risk of prostate cancer.

Examination of polymorphic glutathione S-transferase (GST) genes, tobacco smoking and prostate cancer risk among men of African descent: a case-control study

BACKGROUND

Polymorphisms in glutathione S-transferase (GST) genes may influence response to oxidative stress and modify prostate cancer (PCA) susceptibility. These enzymes generally detoxify endogenous and exogenous agents, but also participate in the activation and inactivation of oxidative metabolites that may contribute to PCA development. Genetic variations within selected GST genes may influence PCA risk following exposure to carcinogen compounds found in cigarette smoke and decreased the ability to detoxify them. Thus, we evaluated the effects of polymorphic GSTs (M1, T1, and P1) alone and combined with cigarette smoking on PCA susceptibility.

METHODS

In order to evaluate the effects of GST polymorphisms in relation to PCA risk, we used TaqMan allelic discrimination assays along with a multi-faceted statistical strategy involving conventional and advanced statistical methodologies (e.g., Multifactor Dimensionality Reduction and Interaction Graphs). Genetic profiles collected from 873 men of African-descent (208 cases and 665 controls) were utilized to systematically evaluate the single and joint modifying effects of GSTM1 and GSTT1 gene deletions, GSTP1 105 Val and cigarette smoking on PCA risk.

RESULTS

We observed a moderately significant association between risk among men possessing at least one variant GSTP1 105 Val allele (OR = 1.56; 95%CI = 0.95-2.58; p = 0.049), which was confirmed by MDR permutation testing (p = 0.001). We did not observe any significant single gene effects among GSTM1 (OR = 1.08; 95%CI = 0.65-1.82; p = 0.718) and GSTT1 (OR = 1.15; 95%CI = 0.66-2.02; p = 0.622) on PCA risk among all subjects. Although the GSTM1-GSTP1 pairwise combination was selected as the best two factor LR and MDR models (p = 0.01), assessment of the hierarchical entropy graph suggested that the observed synergistic effect was primarily driven by the GSTP1 Val marker. Notably, the GSTM1-GSTP1 axis did not provide additional information gain when compared to either loci alone based on a hierarchical entropy algorithm and graph. Smoking status did not significantly modify the relationship between the GST SNPs and PCA.

CONCLUSION

A moderately significant association was observed between PCA risk and men possessing at least one variant GSTP1 105 Val allele (p = 0.049) among men of African descent. We also observed a 2.1-fold increase in PCA risk associated with men possessing the GSTP1 (Val/Val) and GSTM1 (*1/*1 + *1/*0) alleles. MDR analysis validated these findings; detecting GSTP1 105 Val (p = 0.001) as the best single factor for predicting PCA risk. Our findings emphasize the importance of utilizing a combination of traditional and advanced statistical tools to identify and validate single gene and multi-locus interactions in relation to cancer susceptibility.

Expressed sequence tags (ESTs) and single nucleotide polymorphisms (SNPs): What large-scale sequencing projects can tell us about ADME

To date over 800 complete genomes have been sequenced, with many more partially complete. Coupled with the large amount of mRNA transcript sequence data being produced from expression studies, there is now a daunting amount of information available to the research scientist. This review examines how this information may be best used, focusing on examples from sequences encoding absorption, distribution, metabolism and excretion (ADME)-related proteins in particular. Through the use of phylogenetic, splice variant and single nucleotide polymorphism (SNP) analysis, the review examines not only how insights into species-specific responses to drug exposure may be gained, but also how best to utilize this information to predict both individual human responses and the impact of population variance in response.

Cytochrome p450 1A1 gene polymorphisms in patients with psoriatic arthritis

OBJECTIVE

To investigate the associations of cytochrome p450 1A1 (CYP1A1) gene polymorphisms with susceptibility to psoriatic arthritis in Taiwan.

METHODS

CYP1A1 gene polymorphisms were determined in 52 patients with psoriatic arthritis and in 90 healthy controls by polymerase chain reaction/restriction fragment length polymorphism.

RESULTS

The genotype frequency of CYP1A1 4889A/G was significantly increased in patients with psoriatic arthritis in comparison with healthy controls. The phenotype frequency of CYP1A1 4889G was also significantly increased in patients with psoriatic arthritis. The genotype frequency of CYP1A1 4887C/A was significantly higher in patients with psoriatic arthritis than in controls. The allele and phenotype frequencies of 4887A were also significantly increased in patients with psoriatic arthritis. We also found that the association of CYP1A1 4887A with psoriatic arthritis was independent of 4889G but a synergistic effect was present between CYP1A1 4887A and 4889G. The CYP1A1 4889A/G and 4887C/A polymorphisms were not associated with the manifestations and severity of psoriatic arthritis.

CONCLUSION

CYP1A1 4887A and 4889G may be precipitating factors for susceptibility to psoriatic arthritis in Taiwan. An additive effect was found between CYP1A1 4887A and 4889G.

GLUTATHIONE S-TRANSFERASE GENE POLYMORPHISM AND ISCHEMIC CEREBROVASCULAR DISEASE

Glutathione S-transferase polymorphisms (GST) were examined in 142 cases with ischemic cerebrovascular disease (ICVD) to explore whether the GST polymorphisms confer a risk to an individual to develop ICVD. Tobacco smoke is a major cause of both cancer and vascular disease. The subjects were therefore stratified with ICVD for smoking status, and then the authors examined whether polymorphisms in this detoxification enzyme gene, GST, influence risk of ICVD. The GST genotype was analyzed by the polymerase chain reaction. Neither GSTM1 nor GSTT1 genotypes in the ICVD group was significantly different from the control group (n=344), even in smokers. The authors attempted the combined analysis for GSTM1 and GSTT1 genotypes in ICVD for smoking status. No significant association was observed among the combined genotypes and ICVD. The observations do not confirm the effect of the GSTM1 and GSTT1 genotypes as a risk factor for ICVD, even in smokers. However, this approach provides a way of addressing the hypothesis that environmental genotoxins could play a role in the etiopathogenesis of ICVD.

An updating meta-analysis of the GSTM1, GSTT1, and GSTP1 polymorphisms and prostate cancer: a HuGE review

It has been postulated that individuals with GSTM1, GSTT1 deficiency and, GSTP1 (105Ile/Val transition) have increased susceptibility to carcinogens and are more likely to develop prostate cancer. In recent years, GST status has been extensively studied as a prostate cancer risk factor; however, the results are inconsistent. To re-examine this controversy, we have undertaken an updating meta-analysis of 29 studies with GSTM1 genotyping (4,564 prostate cancer cases and 5,464 controls), 22 studies with GSTT1 genotyping (3,837 cases and 4,552 controls), and 24 studies with GSTP1 genotyping (5,301 cases and 5,621 controls). The random effects odds ratio was 1.33 [95% confidence interval (95% CI): 1.15, 1.55; I(2) = 68.9%, P for heterogeneity = 0.00] for the GSTM1 null versus present genotype and 1.05 (95% CI: 0.86, 1.27; I(2) = 68.2%, P for heterogeneity = 0.00) for the GSTT1 null versus present genotype, and 1.06 (95% CI: 0.91, 1.24; I(2) = 71.5%, P for heterogeneity = 0.00) for the GSTP1-Val versus GSTP1-Ile allele. For GSTM1 polymorphism, similar results reached in Caucasians and Asians, with exception for Africans. No association between GSTT1 or GSTP1 polymorphisms and prostate cancer risk was detected in different racial. In conclusion, the major finding of our study suggested that GSTM1 polymorphism conferred an increasing risk of prostate cancer on a wide population basis, however, no relationship was found between GSTT1 and GSTP1 status and the risk of prostate cancer.