Role of the N-acetyltransferase 2 detoxification system in thyroid cancer susceptibility.

PURPOSE: Genetic polymorphisms in genes encoding for enzymes involved in the biotransformation of carcinogens have been shown to be relevant as risk for cancer and may be of considerable importance from a public health point of view. Considering that N-acetyltransferase 2 (NAT2) polymorphisms modulate the response to ionizing radiation, the strongest risk factor recognized to cause differentiated thyroid cancer (DTC) thus far, we sought to determine the influence of NAT2 detoxification system on thyroid cancer susceptibility. EXPERIMENTAL DESIGN: We conducted a prospective case-control study, comparing 195 patients presenting with DTC that were previously genotyped for GSTT1, GSTM1, GSTP1, and CYP1A1, comprising 164 papillary carcinomas and 31 follicular carcinomas, with 196 control individuals paired for gender, age, ethnicity, diet routine, lifetime occupational history, smoking history, general health conditions, and previous diseases. We used PCR-RFLP assays and the combination of 6 variant alleles to define 18 NAT2 haplotypes that characterized slow, intermediate, or rapid phenotypes. RESULTS: A multivariate logistic regression analysis identified the presence of *12A and the absence of *12B, *13, *14B, *14D, *6A, and *7A NAT2 haplotypes as risk factors for DTC. The inheritance of a rapid acetylation phenotype doubled the risk for a papillary carcinoma (odds ratio, 2.024; 95% confidence interval, 1.252-3.272). We found no relationship between genotypes and clinical, pathologic, or laboratory features of patients or between genotypes and outcome. CONCLUSIONS: We showed that NAT2 genotypes and the NAT2 rapid acetylation phenotype are important susceptibility factors for DTC, suggesting that NAT2 detoxification system is involved in this tumor pathogenesis.

Genetic polymorphisms associated with cigarette smoking and the risk of Graves' disease.

OBJECTIVE: Cigarette smoking is a well-recognized risk factor of Graves' disease and, particularly, Graves' ophthalmopathy. Hence, germline polymorphisms of detoxification genes and genes belonging to the major DNA repair-apoptosis pathways might have an important role in disease susceptibility. In addition, as some of these genes are regulated by thyroid hormones, they may affect the patients' outcomes. We aimed to assess the influence of the GST, CYP and TP53 gene polymorphisms in the risk of Graves' disease and its outcome. DESIGN: Prospective case-control study. PATIENTS: A PCR-based strategy was used for GSTT1, GSTM1, GSTP1, CYP1A1 and TP53 codon 72 genotypes in a group of 400 Graves' disease patients, and to compare them to 574 control individuals with similar environmental exposure features. RESULTS: GSTM1 and GSTT1 genotypes were equally distributed in cases and controls, respectively. However, GSTP1 (P < 0.0001), CYP1A1 (P < 0.0033) and Pro/ProTP53 (P < 0.0035) variants appeared more frequently in Graves' disease patients than in controls. A multivariate analysis indicated that cigarette smoking and inheritance of GSTP1, CYP1A1 and Pro/ProTP53 variants were important risk factors for Graves' disease, but only smoking appeared as an independent risk factor for Graves' ophthalmopathy. There was no association between clinical features, including ophthalmopathy or treatment outcome, and the studied genotypes. CONCLUSION: We concluded that GSTP1, CYP1A1 and TP53, but not GSTT1 and GSTM1 germline polymorphisms, may be associated with smoking-related Graves' disease susceptibility and configure a risk profile for the disease. However, these polymorphisms do not influence the patients' response to treatment.

Influence of the glutathione s-transferase gene polymorphisms on the susceptibility to basal cell skin carcinoma.

BACKGROUND: The identification of groups at high risk is fundamental to determine preventive strategies for skin cancer. Destructive reactive oxygen species produced by UVA or chemical carcinogens are metabolized by a series of enzymes. Polymorphisms of genes encoding for these enzymes may produce defective proteins with a diminished ability to detoxify a wide range of carcinogens. AIMS: To ascertain the influence and potential interactions of several polymorphisms of genes encoding four important antioxidant GST enzymes in the susceptibility to cancer among Brazilians. MATERIAL AND METHODS: We compared the genotypes of Glutathione S-Transferase mu, theta, pi and omega (GSTM1, GSTT1, GSTP1 and GSTO2) in a group of 102 patients with skin lesions and 124 controls. RESULTS: Patients with Basal Cell Skin Carcinoma (BCC) presented the combined GSTM1-GSTT1+ genotype more frequently (49.1%) than controls (29.8%) (Fisher test; p=0.04), conferring a 2.273 (Odds Ratio; 95% CI=1.199-4.308) higher risk for BCC. We were not able to find any other association between genotypes or between any genotype and the patients' clinical features. CONCLUSIONS: The GST profile may help identify Brazilian individuals at higher risk for BCC.

Influence of the glutathione s-transferase gene polymorphisms on the susceptibility to basal cell skin carcinoma

Background: The identification of groups at high risk is fundamental to determine preventive strategies for skin cancer. Destructive reactive oxygen species produced by UVA or chemical carcinogens are metabolized by a series of enzymes. Polymorphisms of genes encoding for these enzymes may produce defective proteins with a diminished ability to detoxify a wide range of carcinogens. Aims: To ascertain the influence and potential interactions of several polymorphisms of genes encoding four important antioxidant GST enzymes in the susceptibility to cancer among Brazilians. Material and methods: We compared the genotypes of Glutathione S-Transferase mu, theta, pi and omega (GSTM1, GSTT1, GSTP1 and GSTO2) in a group of 102 patients with skin lesions and 124 controls. Results: Patients with Basal Cell Skin Carcinoma (BCC) presented the combined GSTM1-GSTT1+ genotype more frequently (49.1 percent) than controls (29.8 percent) (Fisher test; p =0.04), conferring a 2.273 (Odds Ratio; 95 percent CI =1.199-4.308) higher risk for BCC. We were not able to find any other association between genotypes or between any genotype and the patients' clinical features. Conclusions: The GST profile may help identify Brazilian individuals at higher risk for BCC.

Antecedentes: La identificación de grupos en riesgo elevado es fundamental en la determinación de las estrategias preventivas para el cáncer de la piel, el maligno humano más común. Las especies reactivas destructivas del oxígeno producidas por UVA o los agentes carcinógenos químicos son metabolizadas por una serie de enzimas. Los polimorfismos de los genes que codifican para estas enzimas pueden producir las enzimas defectuosas con una capacidad disminuida de desintoxicar una amplia gama de agentes carcinógenos. Objetivo: Este estudio fue diseñado para comprobar las interacciones de la influencia y del potencial de varios polimorfismos de los genes que codificaban 4 enzimas importantes del antioxidante GST en la susceptibilidad al cáncer entre brasileños. Métodos: Comparamos los genotipos del mu del S-Transferase del Glutathione, de la theta, de pi y de Omega (GSTM1, GSTT1, GSTP1 y GSTO2) en un grupo de 102 lesiones de piel y de 124 controles. Resultados: Los pacientes con el carcinoma basocelular (BCC) presentaron el genotipo combinado de GSTM1-GSTT1+ más frecuente (49,1 por ciento) que los controles (29,8 por ciento) (Fisher test; p =0,04), confiriendo 2.273 (Odds Ratio 95 por ciento CI =1.199-4.308) un riesgo más alto para BCC. No encontramos ninguna otra asociación entre los genotipos o entre ningún genotipo y características clínicas de los pacientes. Conclusiones: Sugerimos que el perfil de GST pueda ayudar a identificar a individuos brasileños en un riesgo más alto para BCC.

Smoking and susceptibility to thyroid cancer: an inverse association with CYP1A1 allelic variants.

In contrast to most human malignancies, epidemiologic studies have frequently reported a reduced risk of differentiated thyroid cancer in tobacco consumers. Cytochrome P4501A1 (CYP1A1) gene variants may be related to an increased capacity to activate polycyclic aromatic hydrocarbons, producing highly reactive electrophilic intermediates that might damage DNA. Hence, the germline inheritance of a wild-type CYP1A1 gene may decrease the susceptibility for thyroid cancer. The present study was designed to investigate CYP1A1 (m1 and m2) role in thyroid tumorigenesis and its connection with GSTM1, GSTT1, GSTP1, GSTO1, and codon 72 of p53 genotypes. A total of 248 patients with thyroid nodules, including 67 benign goiters, 13 follicular adenomas, 136 papillary carcinomas, and 32 follicular carcinomas, and 277 controls with similar ethnic backgrounds were interviewed on their lifetime dietary and occupational histories, smoking habit, previous diseases, and other anamnestic data. DNA was extracted from a blood sample and submitted to PCR-restriction fragment length polymorphism assays. The wild-type CYP1A1m1 genotype was more frequent among papillary carcinoma patients (74.26%) than in the control population (62.45%; P=0.0147), reducing the risk for this type of cancer (odds ratio=0.564; 95% confidence interval=0.357-0.894). A multiple logistic regression analysis showed an inverse correlation between cigarette smoking (P=0.0385) and CYP1A1 germline inheritance (P=0.0237) with the susceptibility to papillary carcinomas. We were not able to find any correlation between smoking, clinical features, parameters of aggressiveness at diagnosis or during follow-up, and any of the GST or CYP genotypes considered separately or in different combinations. We suggest that CYP1A1 genotype might be associated with the reported reduced risk to papillary carcinomas among smokers.

Polymorphisms at exon 4 of p53 and the susceptibility to herpesvirus types 6 and 1 infection in renal transplant recipients.

In order to replicate their own genome in the host nucleus, herpesviruses have to overcome the barrier presented by p53 gene. Variants of codon 72 and codon 47 of exon four decrease the ability of p53 to induce apoptosis. In order to investigate the influence of this germline inheritance on the susceptibility to herpesvirus type 6 (HHV6) and 1 (HHV1) infection, we examined 78 renal transplant recipients and 151 controls. HHV6 infection was more frequent among the renal transplant patients (35.89%) than in the control population (11.25%) (P < 0.001). HHV1 infection rate was similar in renal transplant patients (7.28%) and controls (2.56%). HHV6-positive cases were more frequent among patients with codon 72 of p53 variants (60.71%) than among wild-type p53 patients (28.20%) (P = 0.001) despite the higher frequency of codon 72 of p53 wild-type variant in renal transplant patients compared with controls (64.1% vs. 36.4%; P < 0.001). The presence of a codon 72 of p53 germline variant genotype increased the risk for HHV6 infection more than five times (OR = 5.479; 95% CI = 1.992-15.069). Our data suggest that codon 72 of p53 polymorphism genotyping may be useful to screen for patients at higher risk for post-transplant infections hence identifying individuals that could benefit from preventive treatment.