Acetylation genotype and the genetic susceptibility to prostate cancer in a southern European population

Risk of congenital heart diseases associated with NAT2 genetic polymorphisms and maternal polycyclic aromatic hydrocarbons exposure

OBJECTIVE

N-Acetyltransferase 2 (NAT2) is a phase II xenobiotic-metabolizing enzyme participating in the detoxification of toxic arylamines and aromatic amines. The present study was designed to investigate whether maternal NAT2 genetic polymorphisms are associated with fetal susceptibility to congenital heart diseases (CHDs) and to assess whether the risk is modified by polycyclic aromatic hydrocarbons (PAHs) exposure.

METHODS

We conducted a hospital-based case-control study to investigate the association of NAT2 gene polymorphisms (rs1799930 G/A, rs1208 A/G, and rs1799931 G/A) and the combinations of PAHs exposure and genetic variants with the risk of CHDs. Three hundred fifty-seven mothers of CHDs fetuses and 270 control mothers were recruited. Logistic regression models for the risk of CHDs were applied to determine the effect of NAT2 polymorphisms, as well as gene-exposure interactions.

RESULTS

Our study did not demonstrate an association of maternal NAT2 genetic polymorphisms alone with CHDs occurrence. However, we found that certain genetic polymorphisms of NAT2 in the present of high PAHs exposure have a higher risk of CHDs.

CONCLUSION

Our study suggests that the risk of CHDs associated with maternal NAT2 gene polymorphisms is potentiated by PAHs exposure.

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.

Lack of association between NAT2 polymorphism and prostate cancer risk: a meta-analysis and trial sequential analysis

Previous studies have investigated the association between NAT2 polymorphism and the risk of prostate cancer (PCa). However, the findings from these studies remained inconsistent. Hence, we performed a meta-analysis to provide a more reliable conclusion about such associations. In the present meta-analysis, 13 independent case-control studies were included with a total of 14,469 PCa patients and 10,689 controls. All relevant studies published were searched in the databates PubMed, EMBASE, and Web of Science, till March 1st, 2017. We used the pooled odds ratios (ORs) with 95% confidence intervals (CIs) to evaluate the strength of the association between NAT2*4 allele and susceptibility to PCa. Subgroup analysis was carried out by ethnicity, source of controls and genotyping method. What's more, we also performed trial sequential analysis (TSA) to reduce the risk of type I error and evaluate whether the evidence of the results was firm. Firstly, our results indicated that NAT2*4 allele was not associated with PCa susceptibility (OR = 1.00, 95% CI= 0.95–1.05; P = 0.100). However, after excluding two studies for its heterogeneity and publication bias, no significant relationship was also detected between NAT2*4 allele and the increased risk of PCa, in fixed-effect model (OR = 0.99, 95% CI= 0.94–1.04; P = 0.451). Meanwhile, no significant increased risk of PCa was found in the subgroup analyses by ethnicity, source of controls and genotyping method. Moreover, TSA demonstrated that such association was confirmed in the present study. Therefore, this meta-analysis suggested that no significant association between NAT2 polymorphism and the risk of PCa was found.

TP53 polymorphisms in sporadic North Indian breast cancer patients

BACKGROUND

The purpose of this study was to evaluate the potential association of five (p.P47S, p.R72P, PIN3 Ins16bp, p.R213R and r.13494g>a) polymorphisms of TP53 with the risk of developing breast cancer in North Indian Punjabi population.

METHODS

We screened DNA samples of 200 sporadic breast cancer patients (197 females and 3 males) and 200 unrelated healthy, gender and age matched individuals for the polymorphisms.

RESULTS

For the p.P47S polymorphism, we observed the PP genotype in 99.5% of the patients and PS genotype in only 1 patient. All the controls had the wild type PP genotype. The frequency of RR, RP and PP genotype of p.R72P was 23.5% vs 33.5%, 51.5% vs 45.5% and 25% vs 21% in patients and controls respectively. Heterozygous (RP) genotype was increased in breast cancer patients as compared to controls (51.5 vs 45.5%) and showed 1.61 fold significantly increased risk for breast cancer (OR=1.61, 95% CI, 1.01-2.58, p=0.04). In breast cancer patients the frequencies of A1A1, A1A2 and A2A2 genotypes of PIN3 Ins16bp polymorphism were 67%, 26% and 7% respectively whereas in controls the genotype frequencies were 68.5%, 27.5% and 4% respectively, with no significant difference. For p.R213R (c.639A>G), all individuals had homozygous wild type genotype. The frequencies of GG, GA and AA genotypes of TP53 r.13494g>a polymorphism were 62 vs 67.5%, 33 vs 28% and 5 vs 4.5% in patients and controls respectively, again without significant difference. We observed that RP- A1A1 genotype combination of p.R72P and PIN3 Ins16bp and RP-GG combination of p.R72P and r.13494g>a polymorphism showed significant risk of breast cancer (OR=1.65, 95%CI: 0.98-2.78, p=0.05; OR=1.72, 95%CI: 1.01-2.92, p=0.04).

CONCLUSION

The results of present study indicated that among the five TP53 polymorphisms investigated, the p.R72P polymorphism, and the RP-A1A1 and RP-GG genotype combination contribute to breast cancer susceptibility in North Indians.

Synergism between the N-acetyltransferase 2 gene and oxidant exposure increases the risk of idiopathic male infertility

N-acetyltransferase (NAT2) is a phase-II xenobiotic-metabolizing enzyme participating in the detoxification of toxic arylamines, aromatic amines and hydrazines. The present study was designed to investigate whether two common single-nucleotide polymorphisms (SNP) of the NAT2 gene (481C>T, rs1799929; 590G>A, rs1799930) are associated with susceptibility to idiopathic male infertility and to assess if the risk is modified by oxidant and antioxidant exposures. A total 430 DNA samples (203 infertile patients and 227 fertile men) were genotyped for the polymorphisms by PCR and restriction fragment length polymorphism. No association was found between the NAT2 polymorphisms and idiopathic male infertility. However, gene-environment interaction analysis revealed that a low-acetylation genotype, 590GA, was significantly associated with increased disease risk in men who had environmental risk factors such as cigarette smoking (OR 1.71, 95% CI 1.02-2.87, P = 0.042), alcohol abuse (OR 2.14, 95% CI 1.08-4.27, P = 0.029) and low fruit/vegetable intake (OR 1.68, 95% CI 1.01-2.79, P = 0.04). This pilot study found, as far as is known for the first time, that the polymorphism 590G>A of NAT2 is a novel genetic marker for susceptibility to idiopathic male infertility, but the risk is potentiated by exposure to various environmental oxidants.

Variation in N-acetyltransferase 2 (NAT2), smoking and risk of prostate cancer in the Slovak population

N-acetyltransferase 2 (NAT2) is an enzyme involved in the biotransformation of xenobiotics, mainly aromatic and heterocyclic amines and hydrazines, all of which represent an important class of carcinogens found in tobacco smoke. Polymorphism in NAT2 gene is reported to be associated with susceptibility to various types of cancer. This study investigated the relationship between the NAT2 polymorphism and the risk of prostate cancer with reference to the link between cigarette smoking and the xenobiotic-metabolizing enzyme NAT2. Overall, 281 cases and 395 controls from Slovakia were studied using polymerase chain reaction-restriction fragment length polymorphism assay. We found no statistically significant association between NAT2 genotypes and prostate cancer risk (slow acetylation vs. rapid acetylation: OR 1.13; 95 % CI 0.83-1.55). We report here a statistically significant correlation between the NAT2*5C/NAT2*6A slow acetylator genotype and the risk for developing prostate cancer (OR 2.91; 95 % CI 1.43-5.94; p = 0.003) when compared with the rapid phenotype. Smokers with NAT2 rapid phenotype had a five percent (5 %) reduced risk of prostate cancer compared with non-smokers carrying the rapid acetylator genotype. The association was reversed among smokers and non-smokers with NAT2 slow phenotype. On the basis of the foregoing, we conclude that the NAT2 phenotypes whether alone or in association with smoking do not correlate with susceptibility to prostate cancer within the Slovak population.

Targeting epigenetics for the treatment of prostate cancer: recent progress and future directions

Epigenetic aberrations contribute to prostate cancer carcinogenesis and disease progression. Efforts have been made to target DNA methyltransferase and histone deacetylases (HDACs) in prostate cancer and other solid tumors but have not had the success that was seen in the hematologic malignancies. Oral, less toxic, and more specific agents are being developed in solid tumors including prostate cancer. Combinations of epigenetic agents alone or with a targeted agent such as androgen receptor signaling inhibitors are promising approaches and will be discussed further.

Effects of single nucleotide polymorphisms on human N-acetyltransferase 2 structure and dynamics by molecular dynamics simulation

Background

Arylamine N-acetyltransferase 2 (NAT2) is an important catalytic enzyme that metabolizes the carcinogenic arylamines, hydrazine drugs and chemicals. This enzyme is highly polymorphic in different human populations. Several polymorphisms of NAT2, including the single amino acid substitutions R64Q, I114T, D122N, L137F, Q145P, R197Q, and G286E, are classified as slow acetylators, whereas the wild-type NAT2 is classified as a fast acetylator. The slow acetylators are often associated with drug toxicity and efficacy as well as cancer susceptibility. The biological functions of these 7 mutations have previously been characterized, but the structural basis behind the reduced catalytic activity and reduced protein level is not clear.

Methodology/Principal Findings

We performed multiple molecular dynamics simulations of these mutants as well as NAT2 to investigate the structural and dynamical effects throughout the protein structure, specifically the catalytic triad, cofactor binding site, and the substrate binding pocket. None of these mutations induced unfolding; instead, their effects were confined to the inter-domain, domain 3 and 17-residue insert region, where the flexibility was significantly reduced relative to the wild-type. Structural effects of these mutations propagate through space and cause a change in catalytic triad conformation, cofactor binding site, substrate binding pocket size/shape and electrostatic potential.

Conclusions/Significance

Our results showed that the dynamical properties of all the mutant structures, especially in inter-domain, domain 3 and 17-residue insert region were affected in the same manner. Similarly, the electrostatic potential of all the mutants were altered and also the functionally important regions such as catalytic triad, cofactor binding site, and substrate binding pocket adopted different orientation and/or conformation relative to the wild-type that may affect the functions of the mutants. Overall, our study may provide the structural basis for reduced catalytic activity and protein level, as was experimentally observed for these polymorphisms.

No association between variant N-acetyltransferase genes, cigarette smoking and Prostate Cancer susceptibility among men of African descent

OBJECTIVE: We evaluated the individual and combination effects of NAT1, NAT2 and tobacco smoking in a case-control study of 219 incident prostate cancer (PCa) cases and 555 disease-free men. METHODS: Allelic discriminations for 15 NAT1 and NAT2 loci were detected in germ-line DNA samples using TaqMan polymerase chain reaction (PCR) assays. Single gene, gene-gene and gene-smoking interactions were analyzed using logistic regression models and multi-factor dimensionality reduction (MDR) adjusted for age and subpopulation stratification. MDR involves a rigorous algorithm that has ample statistical power to assess and visualize gene-gene and gene-environment interactions using relatively small samples sizes (i.e., 200 cases and 200 controls). RESULTS: Despite the relatively high prevalence of NAT1*10/*10 (40.1%), NAT2 slow (30.6%), and NAT2 very slow acetylator genotypes (10.1%) among our study participants, these putative risk factors did not individually or jointly increase PCa risk among all subjects or a subset analysis restricted to tobacco smokers. CONCLUSION: Our data do not support the use of N-acetyltransferase genetic susceptibilities as PCa risk factors among men of African descent; however, subsequent studies in larger sample populations are needed to confirm this finding.

Well-done meat consumption, NAT1 and NAT2 acetylator genotypes and prostate cancer risk: the multiethnic cohort study

BACKGROUND

Prostate cancer (PC) is the most common male malignancy in the United States and disparities in risk exist among ethnic/racial groups. A high intake of well-done meat and the presence of the rapid NAT1 and slow NAT2 acetylator genotypes, as modifiers of the carcinogenic effect of heterocyclic amines, were hypothesized to increase PC risk and possibly explain these ethnic differences in risk.

METHODS

This study examined the associations between well-done (red) meat consumption, NAT1 and NAT2 acetylator genotypes, and PC risk among five ethnicities (African American, Native Hawaiian, Japanese American, Latino, and Caucasian) in a case-control study of PC nested within the Multiethnic Cohort study. Cases (n = 2,106) and controls (n = 2,063) were genotyped for eight single nucleotide polymorphisms in NAT1 and seven single nucleotide polymorphisms in NAT2 that characterized all common alleles for these genes. Well-done meat intake was computed based on responses to a detailed food frequency questionnaire including a question on meat preference. Conditional logistic regression was used in the analysis.

RESULTS

There was no evidence of an increased risk associated with preference for well-done meat, intake of well-done meat, and NAT1 or NAT2 genotypes (jointly or separately).

CONCLUSIONS

These results do not support the hypothesis that exposure to heterocyclic amines is associated with risk of PC. However, additional studies with more precise exposure measures are needed.

A meta-analysis of the NAT1 and NAT2 polymorphisms and prostate cancer: a huge review

Studies revealing conflicting results on the role of NAT1 or NAT2 phenotypes on prostate cancer risk led us to perform a meta-analysis to investigate the association of these polymorphisms and prostate cancer risk. The meta-analysis included six studies with NAT1 genotyping (610 prostate cancer cases and 713 controls), and 10 studies with NAT2 genotyping (1,253 cases and 1,722 controls). The fixed effects odds ratio was 0.96 [95% confidence interval (95% CI): 0.75, 1.21; I(2) = 32.9%, P for heterogeneity = 0.189] for the NAT1 genotype, and the random effects odds ratio was 1.10 (95% CI: 0.87, 1.39; I(2) = 49.1%, P for heterogeneity = 0.039) for the NAT2 genotype. For NAT2 polymorphism, a statistically significant association between NAT2 polymorphism and prostate cancer appeared in Asians, but not in Caucasians. In conclusion, the NAT1 or NAT2 phenotypes detoxify carcinogens and their reactive intermediates are unlikely to be the cause of PCa development.

Implication of Xenobiotic Metabolizing Enzyme gene (CYP2E1, CYP2C19, CYP2D6, mEH and NAT2) polymorphisms in breast carcinoma

Background

Xenobiotic Metabolizing Enzymes (XMEs) contribute to the detoxification of numerous cancer therapy-induced products. This study investigated the susceptibility and prognostic implications of the CYP2E1, CYP2C19, CYP2D6, mEH and NAT2 gene polymorphisms in breast carcinoma patients.

Methods

The authors used polymerase chain reaction and restriction enzyme digestion to characterize the variation of the CYP2E1, CYP2C19, CYP2D6, mEH and NAT2 gene in a total of 560 unrelated subjects (246 controls and 314 patients).

Results

The mEH (C/C) mutant and the NAT2 slow acetylator genotypes were significantly associated with breast carcinoma risk (p = 0.02; p = 0.01, respectively). For NAT2 the association was more pronounced among postmenopausal patients (p = 0.006). A significant association was found between CYP2D6 (G/G) wild type and breast carcinoma risk only in postmenopausal patients (p = 0.04). Association studies of genetic markers with the rates of breast carcinoma specific overall survival (OVS) and the disease-free survival (DFS) revealed among all breast carcinoma patients no association to DFS but significant differences in OVS only with the mEH gene polymorphisms (p = 0.02). In addition, the mEH wild genotype showed a significant association with decreased OVS in patients with axillary lymph node-negative patients (p = 0.03) and with decreasesd DFS in patients with axillary lymph node-positive patients (p = 0.001). However, the NAT2 intermediate acetylator genotype was associated with decreased DFS in axillary lymph node-negative patients.

Conclusion

The present study may prove that polymorphisms of some XME genes may predict the onset of breast carcinoma as well as survival after treatment.

Correlations of dietary patterns with prostate health

Both genetic and environmental influences may be involved in etiology of prostate health and prostate cancer. These include ethnic origin, family history, smoking, and diet. Adiposity and excess energy intake are potentially distinct risk factors and positive associations with prostate cancer risk for both were observed among case-control and cohort studies. Some epidemiological studies support an association between dietary fat, particularly saturated or animal fats, and prostate cancer risk. Of these, several suggest reduced risk with low-fat diets high in n-3 fatty acids and increased risk with high-fat diets rich in n-6 fatty acids. Others suggested association with higher meat intake, possibly due to heterocyclic amines and polycyclic aromatic hydrocarbons, produced during grilling or frying. Positive association of prostate cancer risk with dairy intake could involve alpha-methylacyl-CoA racemase activity (required for beta-oxidation of phytanic acid present in dairy products and red meat) or the suppression of vitamin D activity by calcium. Inverse associations were observed with dietary intake of plant foods. These include cereals, soy products, and fruit and vegetable sources of carotenoids. Numerous plant constituents may act synergistically in the prevention and inhibition of prostate disorders. These diet-risk associations may lead to future individualized diet recommendations based upon genetic polymorphisms.

Role of hormonal and other factors in human prostate cancer

American men have a lifetime risk of about 18% for prostate cancer diagnosis. Large international variations in prostate cancer risks and increased risks among migrants from low- to high-risk countries indicate important roles for environmental factors. Major known risk factors include age, family history, and country/ethnicity. Type 2 diabetes appears to reduce risk, while high birth weight and adult height are linked to increased risk of aggressive prostate cancer. Limited evidence supports an association with a history of sexually transmitted infections. A previous meta-analysis of eight cohort studies indicated no associations with plasma androgen, estrogen, or sex hormone binding globulin (SHBG) levels. However, there were dose-response relationships with baseline plasma testosterone levels in two studies that adjusted for other serum hormones and obesity. Finasteride (a drug that blocks testosterone activation) reduced prostate cancer risk by 25%. Low-frequency genes linked to familial prostate cancer only explain a small fraction of all cases. Sporadic cases were linked to relatively common polymorphisms of genes involved in (1) androgen synthesis, activation, inactivation and excretion, (2) hormone and vitamin D receptors, (3) carcinogen metabolism, and (4) DNA repair. Epidemiologic evidence supports protective roles for dietary selenium, vitamin E, pulses, tomatoes/lycopene, and soy foods, and high plasma 1,25-dihydroxyvitamin D levels. There is inadequate evidence that vegetables, fruit, carotenoids, and vitamins A and C reduce risk and that animal fat, alpha-linoleic acid, meat, coffee, and tea increase risk. Two major cohort studies found dose-response relationships with dietary calcium intake. Total dietary energy intake may enhance risk. Limited evidence supports a protective role for physical activity and elevated risk for farmers and other men with occupational pesticide exposure, particularly to organochlorine compounds and phenoxy herbicides. There is inadequate evidence for a relationship with alcohol or smoking. Most known or suspected external risk factors may act through hormonal mechanisms, but our review found little supporting evidence, and substantial further research is needed.

Importance of TP53 codon 72 and intron 3 duplication 16bp polymorphisms in prediction of susceptibility on breast cancer

Background

TP53 is one of major tumour suppressor genes being essential in preservation of genome integrity. Two very common polymorphisms have been demonstrated to contribute to cancer susceptibility and tumour behaviour. The purpose of this study was to evaluate the role of Arg72Pro and PIN3 Ins16bp polymorphisms in TP53 gene as genetic susceptibility and predictive markers to breast cancer.

Methods

We analysed DNA samples from 264 breast cancer patients and 440 controls, for TP53 Arg72Pro and PIN3 Ins16bp polymorphisms using PCR-RFLP.

Results

We observed that women with A2A2 genotype have increased risk for developing breast cancer, either in women with or without familial history (FH) of the disease (OR = 4.40, 95% CI 1.60–12.0; p = 0.004; OR = 3.88, 95% CI 1.18–12.8; p = 0.026, respectively). In haplotype analysis, statistically significant differences were found between TP53 Arg-A2 haplotype frequencies and familial breast cancer cases and the respective control group (OR = 2.10, 95% CI 1.08–4.06; p = 0.028). Furthermore, both TP53 polymorphisms are associated with higher incidence of lymph node metastases.

Conclusion

Our findings suggest TP53 PIN3 Ins16bp polymorphism as a real risk modifier in breast cancer disease, either in sporadic and familial breast cancer. Furthermore, both TP53 polymorphisms are associated with higher incidence of lymph node metastases.

NAT2 and NER genetic variants and sporadic prostate cancer susceptibility in African Americans

Prostate cancer is a common malignancy that disproportionately affects African-American men. Environmental factors and variation in genes responsible for chemical and dietary carcinogen metabolism and DNA damage repair may modulate risk. Fourteen single nucleotide polymorphisms in NAT2 and four NER genes (ERCC1, XPF/ERCC4, XPG/ERCC5 and CSB/ERCC6) were genotyped in a case-control study of 254 African-American prostate cancer cases and 301 healthy controls from Washington, DC. Smoking status, BMI, age and genetic ancestry were included as covariates in the association analyses. We found that individuals homozygous for the XPG/ERCC5 -72C/T promoter polymorphism had a significant reduction in risk, for prostate cancer (OR=0.12; 95% CI=0.03-0.48). A haplotype trend regression test also revealed a protective effect for the haplotype bearing the T allele (P=0.003). In silica analyses suggest a functional implication for the promoter variant since it deletes a GCF transcriptional factor-binding site responsible for the downregulation of transcription. The protective effect of the promoter SNP on risk for prostate cancer was independent of smoking. In contrast, none of the SNPs typed for NAT2, ERCC1, ERCC4 and ERCC6 showed significant association with risk. Additional tests for genotype interactions were not significant. We note that there may be other factors, such as dietary exposures, which may modulate prostate cancer risk in combination with genetic variation within the NAT2 and NER genes. Our results, in combination with previous observations of LOH for ERCC5 in prostate tumors, provide further evidence for a role of XPG/ERCC5 in the etiology of prostate cancer.

Polymorphisms in genes encoding drug metabolizing enzymes and their influence on the outcome of children with neuroblastoma

BACKGROUND

Although several studies have shown that drug metabolizing enzyme gene polymorphisms may influence the impact of therapy in childhood leukemia, no comprehensive investigations have been carried out in children with neuroblastoma. The aim of this study was to identify polymorphisms in the genes encoding phase I and II drug metabolizing enzymes associated with the risk of relapse or death in a cohort of 209 children with neuroblastoma.

METHODS

Real-time PCR allelic discrimination was used to characterize the presence of polymorphisms in DNA from children with neuroblastoma. Three broad gene categories were examined: cytochrome P450, glutathione-S-transferase and N-acetyltransferase. Cumulative event-free survival was computed by the Kaplan-Meier method. The influence of selected factors on event-free survival was tested using the Cox proportional hazards model.

RESULTS

As previously reported, amplification of MYCN (hazards ratio=4.25, 95% confidence interval=2.76-6.56, P<0.001), unfavorable stage (hazard ratio=4.14, 95% confidence interval=2.3-7.47, P<0.001) or age more than 1 year at diagnosis (hazard ratio=1.86, 95% confidence interval=1.19-2.92, P=0.007) were all associated with an increased risk of relapse or death. Carriers of a NAT1*11 allele variant were significantly less likely to relapse or die compared with those with NAT1*10 or other NAT1 allele variants (P<0.001). In multivariate analysis, children who were GSTM1 null were more likely to relapse or die during follow-up after adjusting for MYCN amplification, stage and age at diagnosis (hazard ratio=1.6, 95% confidence interval=1.02-2.9, P=0.04).

CONCLUSIONS

These observations suggest that the NAT1*11 variant and the GSTM1 wild-type genotype contribute to a more favorable outcome in patients treated for neuroblastoma and are the first to demonstrate a relationship between NAT1 and GSTM1 genotypes in childhood neuroblastoma.

The CYP3A4∗1B polymorphism and prostate cancer susceptibility in a Portuguese population

Testosterone exposure has been implicated in prostate carcinogenesis, and genes that alter its metabolism, such as CYP3A4, have been associated with prostate cancer susceptibility. The aim of our study was to assess the relationship between the CYP3A4 *1B polymorphism and its possible role in the development of prostate cancer. DNA samples obtained from the peripheral blood cells of 414 individuals diagnosed with prostate cancer and 337 healthy male donors were used in this case-control study. The CYP3A4*1B polymorphism was analyzed by polymerase chain reaction-restriction fragment length polymorphism methodology. We found no statistically significant differences in the distribution of the CYP3A4*1B genotypes between cases and controls (P = 0.470; odds ratio = 1.191; 95% confidence interval=0.740-1.918), as well as after the stratification of our analysis, according to important clinicopathologic parameters of prostate cancer. Our results suggest that the CYP3A4*1B polymorphism is not associated with prostate cancer risk within the Portuguese population.

Association between FAS polymorphism and prostate cancer development

The role of FAS polymorphisms in prostate cancer has not been studied. Using the PCR-based restriction fragment-length polymorphism methodology, we evaluated FAS gene locus -670 genotypes in DNA from 904 men: 657 prostate cancer patients and 247 healthy controls. We found that carriers of AG or GG genotypes have a statistically significant protection (odds ratio (OR)=0.30; confidence interval (CI): 0.20-0.44 and OR=0.22; CI: 0.12-0.74, respectively) for disease with extra-capsular invasion. Taken together, a 72% protection was found for G allele carriers (OR=0.28; CI: 0.19-0.41). Fas exist as membrane-bound and soluble forms and with opposite roles. They derive from the same gene by alternative splicing. Membrane Fas receptors trigger apoptosis whereas, on the other hand, soluble Fas (sFas) bind to Fas ligand antagonizing Fas-Fas ligand apoptotic pathway. Our results suggest that G allele may reduce sFas levels preventing the apoptotic inhibition caused by the soluble form.

Functional characterization of the A411T (L137F) and G364A (D122N) genetic polymorphisms in human N-acetyltransferase 2

OBJECTIVES

Human N-acetyltransferase 2 (NAT2) genetic polymorphisms may modify drug efficacy and toxicity and cancer susceptibility from carcinogen exposure. Two human NAT2 alleles, NAT2*5I and NAT2*12D, were identified recently. In NAT2*5I, a new single nucleotide polymorphism AT (L137F) was found coexisting with single nucleotide polymorphisms TC (I114T), CT (silent) and AG (K268R). The other allele NAT2*12D consists of a new single nucleotide polymorphism GA (D122N) together with AG (K268R). We undertook a study to characterize these new single nucleotide polymorphisms and NAT2 alleles to further our understanding of genotype/phenotype relationships in human populations.

METHODS

Various human NAT2 alleles were cloned and recombinantly expressed in COS-1 cells and the effects of single nucleotide polymorphisms on NAT2 expression were determined. To further test our hypothesis that AT (L137F) and GA (D122N) accelerate protein degradation, various NAT2 alleles were cloned and expressed in Escherichia coli, which does not possess the ubiquitin-mediated degradation pathway.

RESULTS

Both AT and GA reduced NAT2 immuno-reactive protein to an undetectable level without causing changes in mRNA level. Missense mutants displayed different effects on sulfamethazine N-acetylation activity for both L137 (wild-type: 70.2+/-5.2 nmol/min/mg; L137F: 1.34+/-0.03 nmol/min/mg; L137W: nondetectable; L137I: 34.2+/-2.0 nmol/min/mg; L137G: 0.52+/-0.04 nmol/min/mg) and D122 (wild-type: 70.2+/-5.2 nmol/min/mg; D122R: non-detectable; D122Q: non-detectable; D122E: 1.72+/-0.24 nmol/min/mg). In contrast to the expression in mammalian cells, recombinant NAT2 possessing either of these two single nucleotide polymorphisms showed no reduction in immuno-reactive NAT2 level when expressed in E. coli.

CONCLUSIONS

These findings suggest that both AT (L137F) and GA (D122N) enhance NAT2 degradation, resulting in reduced NAT2 protein and catalytic activity for NAT2 5I and NAT2 12D.

Meat consumption among Black and White men and risk of prostate cancer in the Cancer Prevention Study II Nutrition Cohort

Previous epidemiologic studies have suggested that intake of red meat may be associated with increased risk of prostate cancer. Few studies, however, have examined these associations by race. We examined intake of red meat, processed meat, and poultry in relation to incident prostate cancer among Black and White men in the Cancer Prevention Study II Nutrition Cohort. Participants in the study completed a detailed questionnaire on diet, medical history, and lifestyle in 1992 to 1993. After excluding men with a history of cancer and incomplete dietary information, 692 Black and 64,856 White men were included in the cohort. During follow-up through August 31, 2001, we documented 85 and 5,028 cases of incident prostate cancer among Black and White men, respectively. Cox proportional hazards models were used to estimate rate ratios (RR) and 95% confidence intervals (95% CI). No measure of meat consumption was associated with risk of prostate cancer among White men. Among Black men, total red meat intake (processed plus unprocessed red meat) was associated with higher risk of prostate cancer (RR, 2.0; 95% CI, 1.0-4.2 for highest versus lowest quartile; P(trend) = 0.05); this increase in risk was mainly due to risk associated with consumption of cooked processed meats (sausages, bacon, and hot dogs; RR, 2.7; 95% CI, 1.3-5.3 for highest versus lowest quartile; P(trend) = 0.008). This study suggests that high consumption of cooked processed meats may contribute to prostate cancer risk among Black men in the United States.