CYP1A1, GSTM1, and GSTT1 polymorphisms and the risk of cervical squamous intraepithelial lesions in a multiethnic population

Genic-intergenic polymorphisms of CYP1A genes and their clinical impact

The humancytochrome P450 1A (CYP1A) subfamily genes, CYP1A1 and CYP1A2, encoding monooxygenases are critically involved in biotransformation of key endogenous substrates (estradiol, arachidonic acid, cholesterol) and exogenous compounds (smoke constituents, carcinogens, caffeine, therapeutic drugs). This suggests their significant involvement in multiple biological pathways with a primary role of maintaining endogenous homeostasis and xenobiotic detoxification. Large interindividual variability exist in CYP1A gene expression and/or catalytic activity of the enzyme, which is primarily due to the existence of polymorphic alleles which encode them. These polymorphisms (mainly single nucleotide polymorphisms, SNPs) have been extensively studied as susceptibility factors in a spectrum of clinical phenotypes. An in-depth understanding of the effects of polymorphic CYP1A genes on the differential metabolic activity and the resulting biological pathways is needed to explain the clinical implications of CYP1A polymorphisms. The present review is intended to provide an integrated understanding of CYP1A metabolic activity with unique substrate specificity and their involvement in physiological and pathophysiological roles. The article further emphasizes on the impact of widely studied CYP1A1 and CYP1A2 SNPs and their complex interaction with non-genetic factors like smoking and caffeine intake on multiple clinical phenotypes. Finally, we attempted to discuss the alterations in metabolism/physiology concerning the polymorphic CYP1A genes, which may underlie the reported clinical associations. This knowledge may provide insights into the disease pathogenesis, risk stratification, response to therapy and potential drug targets for individuals with certain CYP1A genotypes.

Physiopathology and effectiveness of therapeutic vaccines against human papillomavirus

Human papillomavirus (HPV) is a well-known sexually transmitted disorder globally. Human papillomavirus (HPV) is the 3rd most common cancer that causes cervical carcinoma, and globally it accounts for 275,000 deaths every year. The load of HPV-associated abrasions can be lessened through vaccination. At present, three forms of prophylactic vaccines, Cervarix, Gadrasil, and Gardasil 9, are commercially accessible but all these prophylactic vaccines have not the ability to manage and control developed abrasions or infections. Therefore, a considerable amount of the population is not secured from HPV infectivity. Consequently, the development of therapeutic HPV vaccines is a crucial requirement of this era, for the treatment of persisting infections, and to stop the progression of HPV-associated cancers. Therapeutic vaccines are a developing trial approach. Because of the constitutive expression of E6 and E7 early genes in cancerous and pre-cancerous tissues, and their involvement in disturbance of the cell cycle, these are best targets for this therapeutic vaccine treatment. For the synthesis and development of therapeutic vaccines, various approaches have been examined comprising cell-based vaccines, peptide/protein-based vaccines, nucleic acid-based vaccines, and live-vector vaccines all proceeding towards clinical trials. This review emphasizes the development, progress, current status, and future perspective of several vaccines for the cure of HPV-related abrasions and cancers. This review also provides an insight to assess the effectiveness, safety, efficacy, and immunogenicity of therapeutic vaccines in the cure of patients infected with HPV-associated cervical cancer.

Polymorphic variants conferring genetic risk to cervical lesions support GSTs as important associated loci

To analyze the association between glutathione S-transferases polymorphisms and the risk of cervical lesions.Case-control studies focusing on the association between glutathione S-transferase polymorphisms and the risk of cervical lesions were collected from the PubMed, Web of Science, Cochrane Library, Embase, Medline, CNKI, VIP and Wanfang databases from inception to August 2018. Pooled odds ratios and 95% confidence intervals were employed to evaluate the strength of the association. Subgroup analysis and sensitivity analysis were used to test the potential discrepancy and robustness, respectively.A total of 30 studies comprising 3961 patients and 4726 healthy controls satisfied the inclusion criteria. Of these, 6 studies contained information about GSTP1, 27 studies contained information about GSTM1, and 22 studies contained information about GSTT1. Our results supported that there was no statistical association between GSTP1 polymorphism and the risk of cervical lesions (odds ratio [OR] = 1.08, P = .40). The GSTM1 null variant showed increased susceptibility to cervical lesions (OR = 1.45, P < .001). Subgroup analysis revealed that the GSTM1 null variant caused cervical lesions among HPV infection cases (OR = 1.69, P = .02) and among the Chinese and Indian populations (OR = 2.24 and OR = 1.87, respectively, P < .001). The GSTT1 null variant increased the risk of cervical lesions in smokers (OR = 1.52, P = .03). The GSTT1 null genotype was also related to high-grade intraepithelial neoplasia (HSIL) and cervical cancer risk (OR = 1.30 and OR = 1.78, respectively, P < .05).The GSTM1 null variant caused cervical lesions, especially among HPV infection cases and among the Chinese and Indian populations. The GSTT1 null variant increased the risk of cervical lesions in smokers and was also related to HISL and cervical cancer risk.

Cytochrome P450 1A1 gene polymorphisms and cervical cancer risk: A systematic review and meta-analysis

OBJECTIVE

This meta-analysis aims to examine whether the MspI and Ile462Val polymorphisms of cytochrome P450 1A1 (CYP1A1) are associated with cervical cancer risk.

METHODS

Eligible case-control studies were identified dated until July 2017. Pooled odds ratios (ORs) were used to assess the strength of the association between the two variants and cervical cancer risk.

RESULTS

Thirteen studies were eligible (2148 cases and 2252 controls) concerning MspI polymorphism and 8 studies were eligible (1466 cases and 1690 controls) for Ile462Val polymorphism. MspI polymorphism seemed to result in cervical cancer risk in any genetic model (C allele vs T allele: OR = 1.44, 95% confidence interval [CI] = 1.16-1.79; heterozygous model: OR = 1.40, 95% CI = 1.08-1.82; homozygous model: OR = 2.22, 95% CI = 1.48-3.33, dominant model: OR = 1.50, 95% CI = 1.14-1.98 and recessive model: OR = 1.80, 95% CI = 1.35-2.41); similar significantly increased risk was found among Caucasians and Asians. Ile462Val polymorphism was associated with elevated cervical cancer risk (Val allele vs Ile allele: OR = 1.85, 95% CI = 1.27-2.67; heterozygous model: OR = 1.42, 95% CI = 1.28-1.61; homozygous model: OR = 2.94, 95% CI = 1.15-7.54; dominant model: OR = 2.00, 95% CI = 1.33-3.00); this finding was replicated upon Caucasian population.

CONCLUSION

This meta-analysis demonstrated that polymorphisms in MspI and Ile462Val of CYP1A1 were risk factors for developing cervical cancer.

Genetic polymorphisms of glutathione S transferase and cervical intraepithelial neoplasia

Aim: The present study aim to analyze the relationship between GST M/T genotypes of glutathione S-transferases and cervical intraepithelial neoplasia.

Materials and Methods: A prospective case-control study has been designed including 69 cases with different degrees of cervical dysplasia and 107 controls. All patients had been examined colposcopically. For every patient both cervical and blood specimen have been obtained. The peripheral blood was used for GST M/T genotyping. The statistical analysis was performed using OR and chi-square at a level of significance inferior to 0.05.

Results: No statistically significant differences had been found between cases and controls for GST T-/M- geno-type (T-/M-, χ2=0.03, p= 0.8610) and T+/M+ χ2=0.65, p = 0.4197. Patients with in situ carcinoma had significant GST genotype association for T-/M+ genotype (OR=4.66, CI 95% [0.6528,24.9725], χ2=4.6, p=0.0314) and for T+/M- genotype (OR=0.12, CI 95% [0.0027,0.9465], χ2=0.05, p=0.0219).

Conclusion: The combination of GST genotypes can be included in a predictive score for patients with cervical carcinoma.

CYP1A1 MspI Polymorphism and Cervical Carcinoma Risk in the Multi-Ethnic Population of Malaysia: a Case-Control Study

BACKGROUND

Tobacco smoking is considered a risk factor for cervical cancer development due to the presence of tobacco based carcinogenic metabolites in cervical cells of female smokers. In this study, we investigated the role of the T3801C (MspI) polymorphism of CYP1A1, a gene encoding an enzyme necessary for the initiation of tobacco based carcinogen metabolism, on cervical cancer risk. The T to C substitution may alter CYP1A1 activities, potentially elevating cervical cancer risk. Since results of gene-disease association studies vary according to the study population, the multi-ethnic population of Malaysia provides an excellent representative cohort for identifying and comparing the cervical cancer risk among the 3 major ethnics in Southeast Asia in relation to CYP1A1 MspI polymorphism.

MATERIALS AND METHODS

A total of 195 Thin Prep Pap smear samples from HPV negative and cancer free females were randomly selected as controls while 106 formalin fixed paraffin embedded samples from females with invasive cervical cancer were randomly selected for the cases group. The polymorphisms were identified using restriction fragment length polymorphism (RFLP) PCR.

RESULTS

We found no significant associations between CYP1A1 MspI polymorphism and cervical cancer in the general Malaysian female population. However, upon ethnic stratification, the variant C/C genotype was significantly associated with a 4.66-fold increase in cervical cancer risk in Malay females (95% CI= 1.21-17.9; p=0.03). No significant association was observed in the Chinese and Indian females. Additionally, there were no significant associations in the dominant model and allele frequency model analysis in both the general and ethnically stratified female population of Malaysia.

CONCLUSIONS

Our findings suggest that the C/C genotype of CYP1A1 MspI polymorphism is associated with the development of cervical carcinoma in the Malay females of Malaysia.

GSTM1, GSTT1, and NQO1 polymorphisms in cervical carcinogenesis

The aim of the study is to investigate the clinical significance of glutathione-S-transferase GSTM1, GSTT1, and NQO1 c.609C>T (rs1800566) genetic polymorphisms in cervical carcinogenesis. GSTM1, GSTT1, and NQO1 polymorphisms together with human papillomavirus (HPV) types were examined in a total of 192 cervical smear in exfoliated cervical cell samples using polymerase chain reaction (PCR) system and real-time polymerase chain reaction (PCR) system. The 19 patients with high-grade squamous intraepithelial lesion had statistically higher frequency of null GSTT1 genotype than 9 with low-grade squamous intraepithelial lesion (LSIL) among the 67 patients with high-risk HPV (P = 0.024). The 24 patients with HSIL had also statistically higher frequency of NQO1 (CT+TT) genotype than 14 with LSIL among the 67 patients with high-risk HPV (P = 0.024). GSTT1 null and NQO1 genotype in cervical cell samples may be associated with more severe precancerous lesions of the cervix in a Japanese population.

The association of GSTM1 and GSTT1 polymorphisms with squamous cell carcinoma of cervix in Pakistan

Gene deletions in GSTM1 and GSTT1 may result in tempering the activation and detoxification of several carcinogens and thereby may increase the risk of cancer pre-disposition. This study aims to investigate the clinical impact of glutathione-S-transferase GSTM1 and GSTT1 polymorphisms on squamous cell carcinoma of cervix (SCCA).The GSTM1 and GSTT1 polymorphisms were analyzed in cervical cancer patients and healthy controls. Touch down multiplex polymerase chain reaction (PCR) strategy was adopted for genotyping of GSTM1 and GSTT1 polymorphisms. The null genotype of GSTM1 exhibited a significantly higher percentage in patients with SCCA (74 %) than in the control group (34.0 %). However, no significant difference was observed in the null genotype of GSTT1 among SCC patients and healthy subjects, respectively. GSTM1 exhibited a significant association with increased risk of squamous cell carcinoma (p < 0.001). The odds ratio for the GSTM1 null genotype was also calculated (odds ratio 3.7484; 95 % confidence interval 1.6562-84834). This suggests that GSTM1 null genotype in cervical cell samples may be associated with more severe precancerous lesions of the cervix.

Functional variants in CYP1A1 and GSTM1 are associated with clearance of cervical HPV infection

OBJECTIVE

We evaluated time to clearance of high risk (HR) HPV infection in relation to functional variants in three genes (CYP1A1, GSTT1, and GSTM1).

METHODS

The study group consisted of 450 HR-HPV infected women from the Atypical squamous cells of undetermined significance-low-grade squamous intraepithelial Lesion Triage Study (ALTS) cohort followed up at the clinical center at Birmingham, Alabama. The Cox proportional hazard model with the Wei-Lin-Weisfeld (WLW) approach was used, controlling for relevant covariates.

RESULTS

Women who were polymorphic for CYP1A1 experienced an HR-HPV clearance rate that was 20% (HR=0.80, p=0.04) lower than women without the polymorphism for CYP1A1, adjusting for all other cofactors. The GSTM1 null genotype was associated with higher HR-HPV clearance rate (HR=1.39, p=0.006). The polymorphism in GSTT1 was not significantly associated with time to clearance of HR-HPV.

CONCLUSIONS

Xenobiotic metabolism genes may influence the natural history of HR-HPV infection and its progression to cervical cancer.

Glutathione S-transferase T1 and M1 polymorphisms and risk of uterine cervical lesions in women from central Serbia

The aim of this study was to investigate the frequencies of GSTT1 and GSTM1 deletion polymorphisms in newly-diagnosed patients with uterine cervical lesions from central Serbia. Polymorphisms of GST genes were genotyped in 97 patients with cervical lesions and 50 healthy women using a multiplex polymerase chain reaction (PCR). The GSTM1 null genotype was significantly more prominent among the patients than in controls (74.2% vs 56.0%), the risk associated with lesions being almost 2.3-fold increased (OR=2.26, 95%CI=1.10-4.65, p=0.03) and 3.17-fold higher in patients above >45 years old (95%CI=1.02-9.79, p=0.04). The analysis of the two genotypes demonstrated that GSTM1 null genotype significantly increased risk only for low grade squamous intraepithelial lesion-LSIL (OR=2.81, 95%CI=1.03-7.68, p=0.04). GSTT1 null genotype or different genotype combinations were not found to be risk factors, irrespective to lesion stages, age or smoking. We found that the risk of cervical lesions might be significantly related to the GSTM1 null genotype, especially in women aged above 45 years. Furthermore, the GSTM1 polymorphism might have greater role in development of early stage lesions.

Glutathione S-transferase polymorphism interactions with smoking status and HPV infection in cervical cancer risk: an evidence-based meta-analysis

BACKGROUND

Human papillomavirus (HPV) infection is considered the major cause of cervical cancer (CC), but a number of infected women do not develop invasive lesions, suggesting the role of genetic susceptibility and environmental co-factors for cancer outbreak. Glutathione S- transferases (GSTs) are multifunctional enzymes that play a key role in the detoxification of varieties of both endogenous products of oxidative stress and exogenous carcinogens.

METHODS

MEDLINE, EMBASE, and Cochrane databases were searched. All studies evaluating the association between GSTM1 polymorphisms and cervical cancer were included. Pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using fixed-or random-effects model.

RESULTS

A total of 23 case-control studies were included in the meta-analysis. The overall result showed that the association between GSTM1 null genotype and risk for cervical cancer was statistically significant (OR = 1.56; 95%CI, 1.39-1.75). Subgroup analyses were performed based on ethnicity, smoking and HPV infection. Our results showed that smokers with null GSTM1 genotype had higher risk of cervical cancer (OR = 2.27, 95%CI, 1.46-3.54). For the ethnicity stratification, significant increased risk of null GSTM1 genotype was found in Chinese and Indian population, but no increased risk in other population was found.

CONCLUSIONS

this meta-analysis provided strong evidence that the GSTM1 genotype is associated with CC development, especially in Chinese and Indian populations. Smoking and HPV infection modified the association between the null GSTM1 genotype and CC.

A comprehensive review on host genetic susceptibility to human papillomavirus infection and progression to cervical cancer

Cervical cancer is the second most common cancer in women worldwide. This is caused by oncogenic types of human papillomavirus (HPV) infection. Although large numbers of young sexually active women get HPV-infected, only a small fraction develop cervical cancer. This points to different co-factors for regression of HPV infection or progression to cervical cancer. Host genetic factors play an important role in the outcome of such complex or multifactor diseases such as cervical cancer and are also known to regulate the rate of disease progression. The aim of this review is to compile the advances in the field of host genetics of cervical cancer. MEDLINE database was searched using the terms, ‘HPV’, ‘cervical’, ‘CIN’, ‘polymorphism(s)’, ‘cervical’+ *the name of the gene* and ‘HPV’+ *the name of the gene*. This review focuses on the major host genes reported to affect the progression to cervical cancer in HPV infected individuals.

Cytochrome P450 1A1 (CYP1A1) gene polymorphisms and cervical cancer risk: a meta-analysis

This meta-analysis aims to examine whether the genotype status of MspI and Ile462Val polymorphisms in Cytochrome-P450 1A1 (CYP1A1) is associated with cervical cancer risk. Eligible case-control studies were identified through search in MEDLINE (end of search: October 2010). Pooled odds ratios (ORs) were appropriately derived from fixed-effects or random effects models. Concerning MspI polymorphism, six studies were eligible (722 cases and 770 controls); four studies were eligible (350 cases and 519 controls) for Ile462Val. MspI polymorphism was associated with elevated cervical cancer risk (for heterozygous TC vs. TT carriers OR = 1.50, 95% CI: 0.93-2.42, random effects; for homozygous CC vs. TT carriers OR = 2.66, 95% CI: 1.14-6.19, random effects). Similarly, Ile462Val polymorphism was associated with elevated cervical cancer risk (for heterozygous Ile/Val vs. Ile/Ile carriers OR = 2.36, 95% CI: 1.10-5.08, random effects; for homozygous Val/Val vs. Ile/Ile carriers OR = 2.73, 95% CI: 1.21-6.15, fixed effects). The results were replicated upon Caucasian subjects, who represented the majority of existing data. The two examined CYP1A1 genotype polymorphisms seem to confer additional risk for cervical cancer. Accumulation of further data seems mandatory for future race-specific analyses and for the demonstration of CYP1A1-smoking interactions.

Analysis of 4 Single-Nucleotide Polymorphisms in Relation to Cervical Dysplasia and Cancer Development Using a High-Throughput Ligation-Detection Reaction Procedure

Background

Host genetic characteristics and environmental factors may correlate with risk for cervical cancer development. Here we describe a retrospective screening study for single nucleotide polymorphisms (SNPs) in genetic markersTP53, MTHFR, CYP1A1,andCYP2E1in 749 patients.

Methods

A multiplex ligation-dependent polymerase chain reaction approach was applied. We used archived material from human papillomavirus tests and correlated SNP genotypes to the corresponding clinical data. Semantic integration was used to identify and evaluate the clinical status from electronic health records.

Results

An association with cervical cancer and high-grade dysplasia was found for the rare homozygous CC genotype (rs4646903) inCYP1A1(odds ratio [OR], 8.862). Odds ratios were also significantly elevated for heterozygousMTHFRCT genotype (rs1801133; OR, 1.457). No significant association was found inTP53(rs1042522) andCYP2E1(rs3813867). In addition, we found smokers at higher risk (OR, 2.688) and identified pregnancies as a significant risk factor (OR, 1.54).

Conclusions

Our protocol enables a feasible way for further retrospective large sample size evaluation of potential genetic markers. This study revealed genetic associations of a rare SNP genotype with cervical dysplasia in one of the largest patient sample to date that warrants further investigation.

Genetic Polymorphism of Cancer Susceptibility Genes and HPV Infection in Cervical Carcinogenesis

It is widely accepted that specific human papillomavirus (HPV) types are the central etiologic agent of cervical carcinogenesis. However, a number of infected women do not develop invasive lesions, suggesting that other environmental and host factors may play decisive roles in the persistence of HPV infection and further malignant conversion of cervical epithelium. Although many previous reports have focused on HPV and environmental factors, the role of host susceptibility to cervical carcinogenesis is largely unknown. Here, we review the findings of genetic association studies in cervical carcinogenesis with special reference to polymorphisms of glutathione-S-transferase (GST) isoforms, p53 codon 72, murine double-minute 2 homolog (MDM2) gene promoter 309, and FAS gene promoter -670 together with HPV types including our recent research results.

Null genotypes of GSTM1 and GSTT1 contribute to risk of cervical neoplasia: an evidence-based meta-analysis

Background and Objectives

Glutathione S-transferases (GSTs) are multifunctional enzymes that play a key role in the detoxification of varieties of both endogenous products of oxidative stress and exogenous carcinogens.

Methods

In this meta-analysis, twenty-five studies were identified by searching PubMed, EMBASE, ISI Web of Science and CBM databases: 23 evaluated GSTM1 and 19 evaluated GSTT1. Crude odds ratios with corresponding 95% confidence intervals were used to estimate the association between GSTM1 and GSTT1 polymorphisms and risk of cervical neoplasia. Subgroup analyses were conducted by pathological history, ethnicity, source of DNA for genotyping, quality score, and matching variable.

Results

The null genotypes of GSTM1 and GSTT1 polymorphisms were associated with a significantly increased risk of cervical neoplasia (for GSTM1: OR = 1.40; 95%CI, 1.19–1.65; for GSTT1: OR = 1.30; 95%CI, 1.05–1.62, respectively). Subgroup analyses showed that the null genotype of GSTM1 increased the risk of cervical neoplasia in Asians, studies with DNA isolation from white blood cells and tissue samples, both high and low quality studies, and matched studies. In GSTM1-GSTT1 interaction analysis, individuals with dual null genotype were associated with a significantly increased risk of cervical neoplasia (OR = 1.72; 95%CI, 1.18–2.51).

Conclusion

These findings indicate that GSTM1 and GSTT1 polymorphisms, particularly GSTM1-GSTT1 interaction, may play critical roles in the development of cervical neoplasia. A conservative manner should be adopted to interpret these results because of obvious heterogeneity between-study, unadjusted data, and relatively small sample size in this meta-analysis. Well designed studies with larger sample size are of great value to confirm these results.

Polymorphisms of the CYP1A1 and CYP2E1 genes in head and neck squamous cell carcinoma risk

Polymorphisms in genes that encode P450 cytochrome enzymes may increase carcinogen activation or decrease their inactivation and consequently, promote the development of cancer. The aims of this study were to identify the MspI-CYP1A1, PstI-CYP2E1 and DraI-CYP2E1 polymorphisms in patients with head and neck cancer and to compare with individuals without cancer; to evaluate the association of these polymorphisms with risk factors and clinical histopathological parameters. In the study group, 313 patients were evaluated for CYP1A1, 217 for CYP2E1 (PstI) and 211 for CYP2E1 (DraI) and in the control group 417, 334 and 374 individuals, respectively. Molecular analysis was performed by PCR-RFLP technique, and chi-square and multiple logistic regression tests were used for statistical analysis. The result of analysis regarding individuals evaluated for CYP1A1 (MspI) showed that age (OR: 8.15; 95% CI 5.57-11.92) and smoking (OR: 5.37; 95% CI 3.52-8.21) were predictors for the disease; for the CYP2E1 (PstI and DraI), there were associations with age (PstI-OR: 9.10; 95% CI 5.86-14.14/DraI-OR: 8.07; 95% CI 5.12-12.72), smoking (PstI-OR: 4.10; 95% CI 2.44-6.89/DraI-OR: 5.73; 95% CI 3.34-9.82), alcohol (PstI-OR: 1.93; 95% CI 1.18-3.16/DraI-OR: 1.69; 95% CI 1.02-2.81), respectively, with disease development. CYP2E1 (PstI) was less frequent in patient group (OR: 0.48; 95% CI 0.23-0.98). Regarding clinical histopathological parameters, CYP1A1 polymorphism was less frequent in the larynx primary anatomic site (OR = 0.45; 95% CI = 0.28-0.73; P = 0.014). In conclusion, we confirm that age, smoking and alcohol consumption are risk factors for this disease and the polymorphisms investigated have no association with the development of head and neck cancer.

Germline polymorphisms of glutathione-S-transferase GSTM1, GSTT1 and p53 codon 72 in cervical carcinogenesis

The clinical significance of glutathione-S-transferase GSTM1, GSTT1 and p53 codon 72 polymorphisms in cervical carcinogenesis was investigated. Germline polymorphisms of GSTM1, GSTT1 and p53 codon 72 together with human papillomavirus (HPV) types were examined in a total of 457 blood and cervical smear samples from normal healthy women and the patients with premalignant and malignant cervical lesions. The 167 patients with low-grade squamous intraepithelial lesion (LSIL), 49 with high-grade SIL (HSIL) and 83 with squamous cell carcinoma (SCC) had significantly higher frequency of high-risk HPV than 158 controls. The 49 patients with HSIL and 83 with SCC had statistically higher frequency of null GSTT1 genotype than 158 controls. There was an increased odds ratio for null GSTT1 genotype in HSIL and SCC cases compared with controls among 191 patients with high-risk HPV. The 67 cases with HPV types 16 and/or 18 had higher frequency of the GSTT1 null genotype than 186 with other types of HPV. There was no statistical difference in the polymorphic frequency of GSTM1 and p53 codon 72 genotypes between SILs and controls with or without high-risk HPV. These results suggest that GSTT1 null genotype may increase the risk of cervical cancer particularly in the cases with high-risk HPV types in a Japanese population.

Interaction between glutathione-S-transferase polymorphisms, smoking habit, and HPV infection in cervical cancer risk

PURPOSE

Human papillomavirus (HPV) infection is considered the major cause of cervical cancer (CC), but a number of infected women do not develop invasive lesions, suggesting the role of genetic susceptibility and environmental co-factors for cancer outbreak. The aim of this study was to investigate whether some GST polymorphisms could influence the risk to develop CC, either by themselves or in combination with smoking habit, in a cohort of high-risk HPV (HR-HPV) infected Italian women.

METHODS

The study population comprises 192 Italian women including 81 HR-HPV infected women bearing cervical lesions and 111 healthy controls. The cases include: 26 low-grade squamous intraepithelial lesions (LSILs), 30 high-grade-SIL, and 25 CCs, while controls were all negative for HPV. DNA was extracted from peripheral blood samples or cytobrush and individuals were genotyped for GSTM1, GSTT1, and GSTP1 polymorphisms using PCR and PCR/RFLP techniques.

RESULTS

On studying the association of GSTs gene polymorphisms with cervical cancer lesions, the combination of GSTM1 null, GSTT1 null and GSTP1 AA genotypes, independently on smoking habit, seems to be related to a 5.7-fold increased risk of developing CLs with a considerable statistical significance (P = 0.0091).

CONCLUSIONS

We suggest that the investigation of multiple gene polymorphisms, versus single genes, could contribute to a better understanding of the effect of susceptibility genes on cancer risk.

Cigarette smoking and glutathione S-transferase M1 polymorphism associated with risk for uterine cervical cancer

AIM

To elucidate the role of tobacco smoking and polymorphisms of carcinogen metabolism genes in cervical carcinogenesis.

METHODS

We analyzed genotypes of nine genes, 11 polymorphisms encoding carcinogen metabolizing enzymes, information on smoking, and the presence of human papillomavirus in 124 Japanese cervical cancer patients and 125 healthy controls.

RESULTS

The incidence of human papillomavirus infection (95.5% vs 9.9%; P < 0.001; odds ratio (OR), 231.98; 95% confidence interval [CI], 57.17-941.22), and smoking (41.1% vs 18.4%; P < 0.001; OR, 3.40; 95% CI, 1.88-6.17) were both significantly higher in patients than in controls. The genotype distributions of CYP1A1, CYP2E1, CYP2A6, NQO1, NAT2, mEH, MPO and GSTT1 genes were not statistically different; however, the ratio of the GSTM1 null genotype was significantly higher in patients than in controls (62.1% vs 47.2%; P = 0.019; OR, 1.83; 95% CI, 1.11-3.04). The incidence of GSTM1 null was significantly higher in the non-smoking group (63.0% vs 47.1%; P = 0.038; OR, 1.92; 95% CI, 1.04-3.54), and not in the smoking group (60.8% vs 47.8%; P = 0.300; OR, 1.69; 95% CI, 0.63-4.56).

CONCLUSIONS

In the current study, risk factors for developing cervical cancer were tobacco smoking and GSTM1 null; however, no association was observed between these two factors. We could not prove that smoking-GSTM1 null interaction was responsible for the increase in cervical cancer among young Japanese, and further studies with more detailed smoking status, not only active but passive smoking, will be required.

Germline polymorphism of cancer susceptibility genes in gynecologic cancer

The multifactorial process of carcinogenesis involves mutations in oncogenes, or tumor suppressor genes, as well as the influence of environmental etiological factors. Common DNA polymorphisms in low penetrance genes have emerged as genetic factors that seem to modulate an individual's susceptibility to malignancy. Genetic studies, which lead to a true association, are expected to increase understanding of the pathogenesis of each malignancy and to be a powerful tool for prevention and prognosis in the future. Here, we review the findings of genetic association studies of gene polymorphisms in gynecologic cancer with special reference to glutathione-S-transferase, FAS/CD95 and p53 genes including our recent research results.

Association of GSTM1, GSTT1, and GSTM3 gene polymorphisms and susceptibility to cervical cancer in a North Indian population

OBJECTIVE

The objective of the study was to evaluate the influence of genetic polymorphisms of GSTM1, GSTT1, and GSTM3 on the susceptibility of cervical cancer.

STUDY DESIGN

Blood samples from 150 women with biopsy-confirmed cervical cancer and 168 healthy controls were analyzed by multiplex polymerase chain reaction (PCR) to detect the presence or absence of GSTM1 and GSTT1. Insertion/deletion polymorphism in intron 6 of GSTM3 was determined by PCR.

RESULTS

The frequencies of homozygous GSTM1 null and GSTT1 null genotypes were found to be significantly higher in cancer patients as compared with healthy controls (P = .009, odds ratio [OR] 1.52, 95% confidence interval [CI], 1.1 to 2.0 and P = .0004, OR 2.4, 95% CI: 1.4 to 4.0, respectively). The AB genotype of GSTM3 also conferred higher risk of cancer (P = .053, OR 1.64, 95% CI, 1.0 to 2.6). However, no significant association of at-risk genotypes was observed with any stages of cervical cancer. Interactions among GSTM1 null, GSTT1 null, and AB genotype of GSTM3 resulted in additive predictive risks of cervical cancer. In case-only analysis, carriers of the AA genotype of GSTM3 among tobacco users were at elevated risk of cervical cancer (P = .024, OR 2.1, 95% CI, 1.0 to 4.1) as compared with AB and BB genotypes.

CONCLUSION

GSTM1 null, GSTT1 null, and GSTM3*AB genotypes may confer higher susceptibility to cervical cancer and cancer risk because at-risk genotypes are additive. Tobacco usage by carriers of GSTM3*AA has enhanced the risk of cervical cancer as compared with nonusers.

Glutathione-S-transferase M1 and T1 and cytochrome P1A1 genetic polymorphisms and susceptibility to cervical intraepithelial neoplasia in Greek women

The aim of the study was to determine the importance of genetic polymorphisms of glutathione-S-transferase T1 and M1 and cytochrome P1A1 genes in the development of cervical intraepithelial neoplasia in Greek women. This was a prospective, case-control study conducted by the Cervical Pathology and Colposcopy Unit of a University Ob/Gyn Department from 1999 to 2003. Cervical smears from 114 controls without any cytological and/or colposcopical evidence of cervical pathology and from 166 women with history of cervical intraepithelial neoplasia (56 CIN I, 54 CIN II and 56 CIN III) were examined with polymerase chain reaction for the above-mentioned genetic polymorphisms, taking also in mind their smoking attitudes. Statistical analysis was performed to detect any association between the null genotype of GSTM1 and GSTT1 genes and the CYP1A1 m1 polymorphism and the severity of cervical intraepithelial neoplasia. The distributions of the GSTT1 and GSTM1 wild-type genotypes were 57.48 and 39.75%, respectively. No woman with homozygous GSTT1 and GSTM1 null/null genotype was identified. CYP1A1 m1 polymorphism frequency was 24.49%. No woman with homozygous CYP1A1 m1/m1 genotype was detected as well. No significant difference in the frequencies of the GSTM1 and GSTT1 null alleles, and the CYP1A1 m1 polymorphism, was found between cases and controls. After application of Mantel-Haenszel chi procedure, there was no linear severity of the lesion and the frequency of these polymorphisms. According to our results, glutathione-S-transferase T1 and M1 and cytochrome P1A1 genetic polymporphisms do not appear to be a risk factor for cervical disease irrespective of smoking habits.

The risk of developing cervical cancer in Mexican women is associated to CYP1A1 MspI polymorphism

The aim of the study was to evaluate the association of two CYP1A1 polymorphisms (Msp1 and exon 7) with cervical cancer in Mexican women considering their smoking habit. The polymorphisms were determined in 310 individuals (155 with cervical cancer and 155 healthy controls). Women with MspI T/C or C/C showed increased risk of developing cervical cancer (3.7- and 8.3-fold increase, respectively) compared to women with T/T genotype. When smoking habit was considered, the risk for non-smokers with T/C and C/C genotypes was similar (5.2 and 4.1, respectively), whereas smoking women with C/C genotype showed a 19.4-fold increase of cervical cancer. Number of child births, number of sexual partners and marital status were strong risk factors for developing cervical cancer in women with T/T genotype; however, in women with T/C genotype, only the number of child births and sexual partners had a significant influence. These results suggest an important role of the CYP1A1 MspI polymorphism in the risk of developing cervical cancer.

Exposure to wood smoke, HPV infection, and genetic susceptibility for cervical neoplasia among women in Colombia

Cervical cancer is the second leading cause of death from cancer among women in Colombia (16/100,000). Infection with high-risk human papillomavirus (HPV) plays a major role in the etiology of high-grade squamous intraepithelial lesions (HSILs). Exposure to chemical agents may be a cofactor for tumor induction, and individual genetic differences in the metabolism of these chemical agents may affect the susceptibility of individuals towards the development of HSIL. In this case-control study, a total of 91 cases with HSIL and 92 healthy controls, frequency-matched by age and place of origin, were recruited, and their frequencies of CYP2E1, GSTM1, and GSTT1 polymorphism were determined. We then evaluated the association of these polymorphisms, by themselves and in combination with wood smoke exposure and HPV-infection status, with the risk of HSIL. The results indicate that GSTM1 and GSTT1 polymorphism were not associated with HSIL, although a small increase in risk was observed for individuals who were GSTT1 null (OR = 1.4, 95% CI = 0.57-3.44). Contrary to other investigations, the c2/c2 variant of the CYP2E1 gene was associated with a significant increase in risk after adjusting for wood smoke exposure (OR = 6.3, 95% CI = 1.10-36.38) or wood smoke exposure and HPV-infection status (OR = 10.7, 95% CI = 1.76-65.58). Wood smoke exposure also increased the risk of HSIL among CYP2E1 c2/c2 HPV-positive women (OR = 3.3, CI = 0.50-22.50); however, the increase did not achieve statistical significance. Our study provides tantalizing evidence that genetic differences in the metabolism of wood smoke carcinogens, particularly metabolism by CYP2E1, may confer susceptibility for HSIL development. Further investigations with larger populations will be needed to confirm this association, which may provide important information for improving cervical cancer prevention programs.

Germline genetic polymorphisms of CYP1A1, GSTM1 and GSTT1 genes in Indian cervical cancer: Associations with tumor progression, age and human papillomavirus infection

OBJECTIVES

Host genetic factors may play a role in human papillomavirus (HPV)-associated tumorigenesis, although the issue continues to be a focus of much debate. Biotransformation is critical in carcinogenic activity of numerous environmental carcinogens. It is therefore possible that polymorphisms of genes producing functional changes in xenobiotic metabolizing enzymes may be susceptible factors in cervical carcinogenesis. This study looked into possible relationships among these factors.

METHODS

In this case-control study, we analyzed leukocyte DNA from a total of 312 subjects for germline polymorphisms of CYP1A1 (m1 and m2), GSTM1 and GSTT1 at various stages of the cervical tumor progression spectrum, using PCR and RFLP.

RESULTS

Both m1 and m2 polymorphisms of the CYP1A1 gene were more frequent among cases (36.1% for m1 and 38.1% for m2) compared to control subjects (18.2% and 17.6% respectively). The odds ratio of a subject with homozygous CYP1A1 m1 and m2 variant being a case was highest (m1 OR = 4.77 [95% CI = 1.28-17.77]; P = 0.02 and m2 OR = 5.48 [95% CI = 1.49-20.19]; P = 0.011) respectively. The distribution of m1 and m2 CYP1A1 genotypes was also studied as a function of age and in relation to the presence of HPV 16 infection. The risk due to CYP1A1 m1 genotype, when adjusted for HPV status, showed a significantly increased risk (OR = 3.58, 95% CI = 1.88-6.81; P = 0.0001). Similar results were observed in the case of CYP1A1 m2 variant and HPV 16. There was a significant over-representation of both m1 (25.9% vs. 13.9%) and m2 (27.9% vs. 13.3%) polymorphisms in older women (46 years or more). GSTM1 and GSTT1 deletions were also prominent among cases (53.7% and 16.3% respectively) compared to controls (32.7% and 9.7% respectively). A higher proportion of both GSTT1 and GSTM1 deletions were also detected in HPV-16-positive subjects.

CONCLUSIONS

These results suggest that polymorphisms in the CYP1A1, GSTM1 and GSTT1 genes may render women more susceptible to the development of cervical cancer. The association between this susceptibility and the presence of human papillomavirus infection further emphasizes the significance of the genetic polymorphisms.

Interaction of passive smoking with GST (GSTM1, GSTT1, and GSTP1) genotypes in the risk of cervical cancer in India

Human papilloma virus (HPV) infection is a major cause of cervix cancer, but a number of infected women do not develop invasive lesions, suggesting that HPV infection in itself is not a sufficient factor and that other cofactors, such as smoking, play an important role in development of cervix cancer. Alongside active cigarette smoking, passive smoking is an independent risk factor for cervix cancer. Smoking maintains cervical HPV infection longer and decreases potential of clearing an oncogenic infection. Thus, it is quite possible that polymorphism at detoxifying enzyme coding loci such as GSTM1, GSTT1, and GSTP1 may determine susceptibility to cervix cancer. This study evaluates the combined effects of genetic polymorphisms of GSTM1, GSTT1, and GSTP1 on susceptibility to cervical cancer and interaction of these genes with smoking. On individual analysis of GSTM1, GSTT1, and GSTP1, it was observed that passive smokers having genotypes GSTM1 (null) (OR = 7.0, 95% CI = 2.19-22.36, P = 0.0005), GSTT1 (null) (OR = 10.2, 95% CI = 1.23-84.18, P = 0.02), and GSTP1 (ile/val) (OR = 6.4, 95% CI = 2.25-18.38, P = 0.0005) have an increased risk of developing cervix cancer. It is thus concluded that cervical cancer risk is increased in passive smokers with GSTM1 (null), GSTT1 (null), and GSTP1 (ile/val) genotypes.

CYP1A1 gene polymorphism as a risk factor for cervical intraepithelial neoplasia and invasive cervical cancer

OBJECTIVE

The purpose of this study was to evaluate the role of CYP1A1*3 gene polymorphism in the development of cervical cancer by comparing patients having cervical intraepithelial neoplasia (CIN) or invasive cervical cancer with control subjects.

METHODS

CYP1A1*3 polymorphism was analyzed using an allele-specific PCR-based method.

RESULTS

In the group of patients with CIN, the frequency of the Ile/Val and of any Val alleles was significantly higher than in the healthy control subjects (OR: 4.51; 95%CI = 2.42-8.43, and OR: 3.71; 95%CI = 2.03-6.78). In the CIN1 group, patients with Ile/Val and any Val genotypes were found to be significantly higher (OR: 10.53; 95%CI = 3.78-29.33 and OR: 8.38; 95%CI = 3.04-23.08). In the CIN2 group, patients with Ile/Val and any Val revealed a 4.06- and 3.23-fold higher risk than those with Ile/Ile (95%CI = 1.54-10.74 and 1.24-8.45). However, the variance in the group of patients with CIN3 did not reach statistical significance. Patients with cervical cancer were analyzed with respect to the histological diagnoses. In the adenocancer group, the estimated ORs with respect to the control subjects were 11.29 for Ile/Val (95%CI = 3.35-38.07) and 8.98 for any Val groups (95%CI = 2.69-30.01), with a statistical significance. Among the squamous cell cancer patients, Ile/Val and any Val were significantly higher than in controls (OR: 5.76; 95%CI = 3.13-10.59 and OR: 5.20; 95%CI = 2.91-9.28). Although Val/Val genotype did not reach a significant value, it was near significance with an OR of 3.03 (95%CI = 0.95-9.68).

CONCLUSION

These results suggest that CYP1A1*3 gene polymorphism is linked to a propensity for cervical carcinogenesis and further series are needed to detect the exact role of this unique variation.

HER-2 codon 655 polymorphism in cervical carcinogenesis

HER-2 codon 655 polymorphism together with human papillomavirus (HPV) types were examined in a total of 279 cervical smear samples. Forty-nine patients with high-grade squamous intraepithelial lesion had higher frequency of high-risk HPV than 167 patients with low-grade squamous intraepithelial lesion and 63 controls. There was no statistical difference in the frequencies of HER-2 Ile/Ile, Ile/Val, and Val/Val genotypes between squamous intraepithelial lesions (SILs) and controls. When the Ile/Ile genotype was compared to the Ile/Val + Val/Val genotypes, there was also no statistical difference in the genotype prevalence between SILs and controls either in 91 or 188 patients with or without high-risk HPV, respectively. These results suggest that the HER-2 polymorphism at codon 655 in cervical cell samples is unlikely to be associated with HPV status and the onset of cervical cancer in a Japanese population.

Genetic polymorphisms of FAS and FASL (CD95/CD95L) genes in cervical carcinogenesis: An analysis of haplotype and gene-gene interaction

OBJECTIVE

Whereas human papillomavirus (HPV) infection is necessary but not sufficient for cervical carcinogenesis, host genetic variations may confer individual susceptibility. Resistance to apoptosis is a hallmark of cancer in which FAS/FAS ligand signaling plays an important role. The present study examines the hypothesis that genetic polymorphisms in FAS and FAS ligand genes, alone or in combination, are associated with cervical carcinogenesis.

METHODS

The genotypes of FAS -670A/G, FAS -1377G/A, and FASL -844C/T were assessed in 143 patients with high-grade squamous intraepithelial lesions (HSIL), 175 patients with invasive squamous cell carcinomas (SCC), and in age-matched controls by real-time PCR with allele-specific TaqMan probes. The status of cervical high-risk HPV infection was determined and adjusted to test the independence of genotype in the risk assessment.

RESULTS

The A-allele and AA-genotype frequencies of FASA -670G were significantly higher in HSIL/SCC than in controls (60% vs. 54%, P = 0.04, OR 1.26 [95% CI 1.01-1.57]; 38.0% vs. 28.6%, P = 0.02, OR 1.70 [95% CI 1.07-2.70]). No association between FAS -1377 or FASL -844 polymorphisms and HSIL/SCC could be identified. The FAS -1377A/-670A haplotype conferred a higher risk for HSIL/SCC (OR 3.05, 95% CI 1.28-7.30) than FAS -670A alone (OR 1.26, 95% CI 1.28-7.30). The interaction between FAS -670AA and FASL -844CC genotypes was associated with a risk of HSIL/SCC (OR 2.13, 95% CI 1.06-4.29) higher than that of the FAS -670AA genotype alone (OR 1.70, 95% CI 1.07-2.70).

CONCLUSIONS

The FAS -1377A/-670A haplotype in combination with FASL -844C is associated with cervical carcinogenesis.

Human papillomavirus and disease mechanisms: relevance to oral and cervical cancers*

Oral squamous cell carcinoma (OSCC) is the sixth most common malignancy and is a major cause of cancer morbidity and mortality worldwide. Carcinoma of the uterine cervix is the most common female malignancy in the world. While cervical cancer is a worldwide disease, oral cancer has the highest incidence in developing countries, especially among tobacco and alcohol users and betel quid chewers. A strong association of cervical and oral cancer with high-risk human papillomavirus (HPV) 16 and 18 infections underlines the importance of the virus in the pathogenesis of these squamous cell carcinomas. Functionally high-risk HPV infection contributes to carcinogenesis and tumor progression predominantly through the actions of two viral oncogenes, E6 and E7. The E6 and E7 genes have been studied in different patient populations and a number of variants have been described. More than 40 variants have been classified and may be related to differences in progression of squamous intraepithelial lesions. The transcription factor, NFkappaB and its activation pathways are frequently targeted by viruses and aberrant constitutive activation of NFkappaB is frequently found in human tumors of diverse tissue origin. Diet-gene interactions are also likely to contribute considerably to the observed inter-individual variations in HPV associated cancer risk, in response to exposures to the nutritional factors that have the potential to promote or protect against cancer.

Cytochrome P450-mediated metabolism of estrogens and its regulation in human

Estrogens are eliminated from the body by metabolic conversion to estrogenically inactive metabolites that are excreted in the urine and/or feces. The first step in the metabolism of estrogens is the hydroxylation catalyzed by cytochrome P450 (CYP) enzymes. Since most CYP isoforms are abundantly expressed in liver, the metabolism of estrogens mainly occurs in the liver. A major metabolite of estradiol, 2-hydroxyestradiol, is mainly catalyzed by CYP1A2 and CYP3A4 in liver, and by CYP1A1 in extrahepatic tissues. However, CYP1B1 which is highly expressed in estrogen target tissues including mammary, ovary, and uterus, specifically catalyzes the 4-hydroxylation of estradiol. Since 4-hydroxyestradiol generates free radicals from the reductive-oxidative cycling with the corresponding semiquinone and quinone forms, which cause cellular damage, the specific and local formation of 4-hydroxyestradiol is important for breast and endometrial carcinogenesis. Changes in the expression level of estrogen-metabolizing CYP isoforms not only alter the intensity of the action of estrogen but may also alter the profile of its physiological effect in liver and target tissues. Generally, many CYP isoforms are induced by the substrates themselves, resulting in enhanced metabolism and elimination from the body. Of particular interest is a novel finding that human CYP1B1 is regulated by estradiol via the estrogen receptor. This fact suggests that the regulation of CYP enzymes involved in estrogen metabolism by estrogen itself would be physiologically significant for the homeostasis of estrogens at local organs. In this mini-review, we discuss the CYP-mediated metabolism of estrogens and the regulation of the estrogen-metabolizing CYP enzymes in relation to the risk of cancer.

Cytochrome P-450 1A1 gene polymorphisms and risk of breast cancer: a HuGE review

Cytochrome P-450 (CYP) 1A1 plays a key role in phase I metabolism of polycyclic aromatic hydrocarbons and in estrogen metabolism. It is expressed predominantly in extrahepatic tissues, including the breast. Four CYP1A1 gene polymorphisms (3801T --> C, Ile462Val, 3205T --> C, and Thr461Asp) have been studied in relation to breast cancer. The 3801C variant is more common than the Val variant. Both variants occur more frequently in Asians than in White populations. The 3205T --> C polymorphism has been observed in African Americans only. Little data are available on the geographic/ethnic distribution of the Thr461Asp polymorphism. The functional significance of the polymorphisms is unclear. In 17 studies, no consistent association between breast cancer and CYP1A1 genotype was found. Meta-analysis found no significant risk for the genotypes 1) 3801C/C (relative risk (RR) = 0.97, 95% confidence interval (CI): 0.52, 1.80) or 3801T/C (RR = 0.91, 95% CI: 0.70, 1.19) versus 3801T/T, 2) Val/Val (RR = 1.04, 95% CI: 0.63, 1.74) or Ile/Val (RR = 0.92, 95% CI: 0.76, 1.10) versus Ile/Ile, or 3) Asp/Asp (RR = 0.95, 95% CI: 0.20, 4.49) or Thr/Asp (RR = 1.12, 95% CI: 0.87, 1.43) versus Thr/Thr. Future studies should explore possible interactions between CYP1A1 and sources of polycyclic aromatic hydrocarbons, markers of estrogen exposure, other lifestyle factors influencing hormonal levels, and other genes involved in polycyclic aromatic hydrocarbon metabolism or hormonal biosynthesis.

Glutathione-S-transferase and p53 polymorphisms in cervical carcinogenesis

OBJECTIVE

To investigate the clinical significance of glutathione-S-transferase GSTM1, GSTT1 and p53 codon 72 polymorphisms in cervical carcinogenesis.

METHODS

GSTM1, GSTT1 and p53 codon 72 polymorphisms together with human papillomavirus (HPV) types were examined in a total of 198 cervical smear samples using multiplex polymerase chain reaction (PCR) and PCR restriction fragment length polymorphism (RFLP) techniques.

RESULTS

Forty-two patients with high-grade squamous intraepithelial lesion (HSIL) had higher frequency of high-risk HPV and null GSTT1 genotype than 102 with low-grade SIL (LSIL) and 54 controls. Thirty-one patients with HSIL had also statistically higher frequency of null GSTT1 genotype than 28 with LSIL among 69 patients with high-risk HPV. There was no statistical difference in p53 Arg, Arg/Pro and Pro genotypes between SILs and controls with or without high-risk HPV.

CONCLUSION

GSTT1 null genotype in cervical cell samples may be associated with more severe precancerous lesions of the cervix in a Japanese population. The p53 codon 72 polymorphism is unlikely to be related to HPV status and the onset of cervical cancer.

Females with paired occurrence of cancers in the UADT and genital region have a higher frequency of either Glutathione S-transferase M1/T1 null genotype

Upper Aero digestive Tract (UADT) is the commonest site for the development of second cancer in females after primary cervical cancer. Glutathione S-transferase (GSTM1 and / or T1) null genotype modulates the risk of developing UADT cancer (primary as well as second cancer). The aim of this study was to evaluate the difference in GST null genotype frequencies in females with paired cancers in the UADT and genital region as compared to females with paired cancers in the UADT and non-genital region. Forty-nine females with a cancer in the UADT and another cancer (at all sites-genital and non-genital) were identified from a database of patients with multiple primary neoplasms and were analyzed for the GSTM1 and T1 genotype in addition to known factors such as age, tobacco habits, alcohol habits and family history of cancer. Frequencies of GSTM1 null, GSTT1 null, and either GSTM1/T1 null were higher in females with paired occurrence of cancer in the UADT and genital site (54%, 33% and 75% respectively) in comparison to females with paired occurrence of cancer in the UADT and non-genital sites (22%, 6% and 24% respectively). The significantly higher inherited frequency of either GSTM1/T1 null genotype in females with a paired occurrence of cancers in UADT and genital region (p = 0.01), suggests that these females are more susceptible to damage by carcinogens as compared to females who have UADT cancers in association with cancers at non-genital sites.

Association of the NAD(P)H: quinone oxidoreductase C609T polymorphism and the risk of cervical cancer in Japanese subjects

OBJECTIVE

In this study, genetic polymorphisms, NQO1 C609T, GSTM1 positive/null, and GSTT1 positive/null, were examined with reference to cervical cancer risk in a population-based incident case-control study in Japanese.

METHODS

The cases comprised 131 cervical cancer patients: 87 cases with squamous cell carcinoma (SCC) and 44 with adenocarcinoma (ADC) or adenosquamous carcinoma (ADSC). Controls were sampled from 320 healthy women who underwent a health checkup.

RESULTS

The cervical cancer risk was substantially elevated with smoking for all cases, SCC cases, and ADC/ADSC cases (OR = 4.50, 95% CI = 2.48-8.17, P < 0.001; OR = 5.68, 95% CI = 2.99-10.78, P < 0.001; and OR = 2.57, 95% CI = 1.09-6.08, P = 0.032; respectively). The frequency of the NQO1 609TT genotype, reported to be associated with null enzyme activity, was higher in individuals with all cases and SCC than in the healthy controls (OR = 1.97, 95% CI = 1.06-3.66, P = 0.032; and OR = 2.42, 95% CI = 1.21-4.82, P = 0.012; respectively), but not in ADC/ADSC cases. Analysis of polymorphisms for GSTM1 and GSTT1 showed no significant differences between cervical cancer patients and controls. In stratification analysis, significant elevated risk of all cases and SCC was associated with the NQO1 609TT genotype among nonsmokers (OR = 2.15, 95% CI = 1.08-4.30, P = 0.030; and OR = 2.83, 95% CI = 1.21-6.31, P = 0.011; respectively), but not smokers. No gene-gene interaction was observed in our case subjects.

CONCLUSION

This is the first report that the NQO1 gene might be important in relation to the risk of squamous cell carcinoma of the cervix.

Familial cervical cancer: case reports, review and clinical implications

We report three Dutch families with familial clustering of (pre)neoplastic cervical disease, review the literature on familial risks of cervical intraepithelial neoplasia (CIN) and cervical cancer, and discuss possible practical guidelines for women with a family history of cervical cancer. Daughters and sisters of women with cervical cancer have been reported to have a relative risk of 1.5-2.3 to develop this type of cancer. From a practical clinical point of view, we suggest that as in women with an increased non-genetic risk to develop cervical cancer (e.g. because of immunosuppressive therapy) increased surveillance to detect this tumour should be considered in women with an increased risk based on family history. Cessation of smoking should be advised. As the use of condoms at least prevents HPV re-infection its use can be recommended as a way to lower the cervical cancer risk. Future studies to determine the genetic contribution to the development of cervical cancer should include the paternal family history of cancer and, because genetic predisposition might express itself as a higher risk to develop precursors of cervical cancer, carcinoma in situ and CIN grade II-III.

Glutathione S-Transferase GSTM1, GSTT1 and p53 Codon 72 Polymorphisms in Human Tumor Cells

The genes of the glutathione S-transferase (GST) family encode enzymes that appear to be critical in cellular protection against the cytotoxic effects, whereas p53 is a tumor suppressor gene. Despite a large number of studies on germline polymorphisms of GSTM1, GSTT1 and p53 genes, there have been very few reports on genotyping of these genes in human malignant tumor cells. In this study, we investigated GSTM1, GSTT1 and p53 codon 72 polymorphisms in a variety of human tumor cell lines originating from different organs to clarify tissue-specific polymorphic frequency of these genes in human solid tumors. The GSTM1 and GSTT1 genetic polymorphisms were evaluated using multiplex PCR techniques and PCR-RFLP analysis was conducted to identify p53 codon 72 genotypes. Gene expression of GSTM1 or GSTT1 was detected by RT-PCR in the cells with respective present genotype for each. Polymorphisms of p53 codon 72 detected by PCR-RFLP were also confirmed using SSCP and sequence analyses. GSTM1 and GSTT1 genotypes were various in 104 cell lines examined. Null GSTM1 genotype was dominant in small cell lung, kidney and ovarian carcinoma cells, whereas null GSTT1 genotype was dominant in cervical and endometrial carcinoma cells. GSTM1 and GSTT1 genotypes in ovarian carcinoma cells were quite similar to those in small cell lung carcinoma cells. Polymorphic frequency of p53 codon 72 was also various among the cells, however, the Pro allele was found in only 1 of 6 kidney, 14 cervical and 4 endometrial carcinoma cell lines. There was a significant difference in GSTM1 and p53 genotypes between 34 small cell and 24 non small cell lung carcinoma cells (P < 0.01). Combined study on the distribution of GSTM1, GSTT1 and p53 genotypes revealed that null GSTM1 genotype was associated with the Arg allele of p53 codon 72 in 58 lung carcinoma cells and null GSTT1 genotype was associated with the Pro/Pro homozygote in 104 tumor cell lines examined. This is the first study examining GSTM1, GSTT1 and p53 codon 72 polymorphisms in a variety of human solid tumor cells and suggesting that polymorphic frequency of these genes may be tissue- and organ-specific. The molecular interaction between GST gene defects and p53 codon 72 genotype in the development of human malignant tumors should be further investigated.

Polymorphisms for chemical metabolizing genes and risk for cervical neoplasia

Infection with high-risk human papillomavirus (HPV) plays a major role in the etiology of cervical cancer (CC). However, most infected women do not develop cancer. Therefore, exposure to other carcinogenic agents may be a contributing risk factor for CC. We investigated the hypothesis that environmental exposure to cigarette smoke and inheritance of polymorphic chemical metabolizing genes (CYP2E1, GSTM1, and mEH) significantly increase the risk for neoplasia. We selected 76 cases with high-grade cervical neoplasia or with invasive CC and 75 matched healthy controls. The collected data support the well-established observation that infection with high-risk HPV is the major risk factor for CC (OR = 75; 95% CI = 26-220). In addition, our data show that women who smoked more than 15 "pack-year" had a significant 6.9-fold increase in risk (95% CI = 1.2-40.3) after adjustment for HPV infection. The CYP2E1 variant genotype did not significantly increase the risk for neoplasia. A significant increase in risk for neoplasia was observed for the low-activity mEH 113 His allele after adjustment for smoking (OR = 3.0; 95% CI = 1.4-6.3). The GSTM1 null genotype was associated with a significant 3.3-fold increased risk for neoplasia (95% CI = 1.0-11.8) compared to women who were GSTM1-positive after adjustment for smoking and HPV infection. Our study suggests that genetic differences in the metabolism of cigarette smoke, particularly GSTM1, may confer susceptibility to CC. Further studies using larger populations will be needed to confirm our observations and to validate data for disease prevention.