Association between N-acetyltransferase 2 (NAT2) genetic polymorphism and development of breast cancer in post-menopausal Chinese women in Taiwan, an area of great increase in breast cancer incidence

Polymorphisms in NAT2 (N-acetyltransferase 2) gene in patients with systemic lupus erythematosus

OBJECTIVE

To investigate potential associations of four substitutions in NAT2 gene and of acetylator phenotype of NAT2 with systemic lupus erythematosus (SLE) and clinical phenotypes.

METHODS

Molecular analysis of 481C>T, 590G>A, 857G>A, and 191G>A substitutions in the NAT2 gene was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique, from DNA extracted from peripheral blood samples obtained from patients with SLE (n=91) and controls (n=97).

RESULTS AND CONCLUSIONS

The 857GA genotype was more prevalent among nonwhite SLE patients (OR=4.01, 95% CI=1.18-13.59). The 481T allele showed a positive association with hematological disorders that involve autoimmune mechanisms, specifically autoimmune hemolytic anemia or autoimmune thrombocytopenia (OR=1.97; 95% CI=1.01-3.81).

Landscape of NAT2 polymorphisms among breast cancer

PURPOSE

The prevalence of phenotypes of Arylamine N-acetyltransferase-2(NAT2) gene (i.e. fast, intermediate and slow acetylators) among ethnic groups, as well as the association studies regarding NAT2 polymorphisms and risk of breast cancer produced inconsistent results. This meta-analysis aimed to clarify whether the selected NAT2 phenotypes have an effect on the susceptibility to breast cancer.

METHODS

After aggregating the frequencies of fast, intermediate and slow phenotypes of NAT2 in breast cancer subjects, the odds ratio and relevant 95% confidence intervals were examined using combined data from all published 36 articles.

RESULTS

Overall, our results did not produce statistical significance for the proposed association, suggesting that there is no association between the selected phenotypes of NAT2 polymorphisms and breast cancer. In subgroup analyses, it was revealed that, as compared with the fast phenotype, intermediate acetylator is protective of the vulnerable White population to breast cancer. In addition, an obvious ethnic/geographic difference was found in the prevalence of fast, intermediate and slow acetylators among world-wide populations.

CONCLUSIONS

Although ethnic and geographic differences in NAT2 polymorphisms were present, this was not associated with the risk of breast cancer in general. Intermediate acetylator is protective for particular ethnic groups, a finding which should be carefully viewed and confirmed in the future studies.

NAT2 polymorphisms combining with smoking associated with breast cancer susceptibility: a meta-analysis

To derive a more precise estimation of the relationship between the slow or rapid acetylation resulting from N-acetyltransferase 2 (NAT2) polymorphisms and breast cancer risk, a meta-analysis was performed. PubMed, Medline, Embase, and Web of Science were searched. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess strength of association. The pooled ORs were performed for slow versus rapid acetylation genotypes. A total of 26 studies including 9,215 cases and 10,443 controls were included in the meta-analysis. Overall, no significantly elevated breast cancer risk was associated with NAT2 slow genotypes when all studies were pooled into the meta-analysis (OR = 1.026, 95% CI = 0.968-1.087). In the subgroup analysis by ethnicity, increased risks were not found for either Caucasians (OR = 1.001, 95% CI = 0.938-1.068) or Asians (OR = 1.155, 95% CI = 0.886-1.506). When stratified by study design, statistically significantly elevated risk associated with NAT2 slow genotypes was only found among hospital-based studies (OR = 1.178, 95% CI = 1.037-1.339). In the subgroup analysis by menopausal status, no statistically significantly increased risk was found in either premenopausal (OR = 1.053, 95% CI = 0.886-1.252) or postmenopausal women (OR = 0.965, 95% CI = 0.844-1.104). When stratified by cumulative smoking exposure, in the subgroup of smokers with high pack-years, NAT2 slow genotypes were significantly associated with increased breast cancer risk (OR = 1.400, 95% CI = 1.099-1.784). In conclusion, this meta-analysis suggested that there is overall lack of association between NAT2 genotypes and breast cancer risk, however, NAT2 polymorphisms when combining with heavy smoking history may contribute to breast cancer susceptibility.

N-acetyltransferase 2 genotype modification of active cigarette smoking on breast cancer risk among hispanic and non-hispanic white women

While it has been demonstrated that cigarette smoke contains aromatic and heterocyclic amines that initiate carcinogenesis, the association between cigarette smoking and breast cancer remains controversial. N-acetyltransferase 2 (NAT2) catalyzes arylamine carcinogen biotransformation and NAT2 genetic polymorphisms may contribute to differential susceptibility to breast cancer. We tested whether NAT2 modified the association between cigarette smoking and breast cancer risk in a population-based study of Hispanic and non-Hispanic white women in the Southwest United States. Data were available for cigarette smoking and NAT2 polymorphisms for 717 cases (Hispanic, 251 and non-Hispanic white, 466) and 735 controls (Hispanic, 245 and non-Hispanic white, 490). NAT2 genotypes were translated into rapid, intermediate, slow, or very slow acetylator phenotypes. Odds ratios (ORs) and 95% confidence intervals (95% CIs) for the joint association of NAT2 with smoking on breast cancer risk were estimated using logistic regression. Non-Hispanic white women were more likely (p < 0.001) than Hispanic women to have a slow (41.7 vs. 33.5%) or very slow (19.0 vs. 11.1%) acetylator status and less likely to have rapid/intermediate phenotypes (39.2 vs. 54.4%). Breast cancer risk was significantly increased in non-Hispanic white women with a very slow acetylator phenotype who smoked: ever versus never (OR, 2.57; 95% CI, 1.49-4.41), never versus former (OR, 2.69; 95% CI, 1.41-5.17) or current (OR, 2.46; 95% CI, 1.07-5.65), and 16 + pack-years (OR, 2.29; 95% CI, 1.16-4.51). Results for Hispanic women were not statistically significant. These findings support smoking as a risk factor for breast cancer among non-Hispanic white women with very slow NAT2 acetylator phenotype.

Differences between human slow N-acetyltransferase 2 alleles in levels of 4-aminobiphenyl-induced DNA adducts and mutations

Aromatic amines such as 4-aminobiphenyl (ABP) require biotransformation to exert their carcinogenic effects. Genetic polymorphisms in biotransformation enzymes such as N-acetyltransferase 2 (NAT2) may modify cancer risk following exposure. Nucleotide excision repair-deficient Chinese hamster ovary (CHO) cells stably transfected with human cytochrome P4501A1 (CYP1A1) and a single copy of either NAT2*4 (rapid acetylator), NAT2*5B (common Caucasian slow acetylator), or NAT2*7B (common Asian slow acetylator) alleles (haplotypes) were treated with ABP to test the effect of NAT2 polymorphisms on DNA adduct formation and mutagenesis. ABP N-acetyltransferase catalytic activities were detectable only in cell lines transfected with NAT2 and were highest in cells transfected with NAT2*4, lower in cells transfected with NAT2*7B, and lowest in cells transfected with NAT2*5B. Following ABP treatment, N-(deoxyguanosin-8-yl)-4-aminobiphenyl (dG-C8-ABP) was the primary adduct formed. Cells transfected with both CYP1A1 and NAT2*4 showed the highest concentration-dependent cytotoxicity, hypoxanthine phosphoribosyl transferase (hprt) mutants, and dG-C8-ABP adducts. Cells transfected with CYP1A1 and NAT2*7B showed lower levels of cytotoxicity, hprt mutagenesis, and dG-C8-ABP adducts. Cells transfected with CYP1A1 only or cells transfected with both CYP1A1 and NAT2*5B did not induce cytotoxicity, hprt mutagenesis or dG-C8-ABP adducts. ABP-DNA adduct levels correlated very highly (r>0.96) with ABP-induced hprt mutant levels following each treatment. The results of the present study suggest that investigations of NAT2 genotype or phenotype associations with disease or toxicity could be more precise and reproducible if heterogeneity within the "slow" NAT2 acetylator phenotype is considered and incorporated into the study design.

Genetic polymorphism in N-Acetyltransferase (NAT): Population distribution of NAT1 and NAT2 activity

N-Acetyltransferases (NAT) are key enzymes in the conjugation of certain drugs and other xenobiotics with an arylamine structure. Polymorphisms in NAT2 have long been recognized to modulate toxicity produced by the anti-tubercular drug isoniazid, with molecular epidemiologic studies suggesting a link between acetylator phenotype and increased risk for bladder cancer. Recent evidence indicates that the other major NAT isozyme, NAT1, is also polymorphic. The current analysis characterizes the main polymorphisms in both NAT2 and NAT1 in terms of their effect on enzyme activity and frequency in the population. Multiple NAT2 alleles (NAT2*5, *6, *7, and *14) have substantially decreased acetylation activity and are common in Caucasians and populations of African descent. In these groups, most individuals carry at least one copy of a slow acetylator allele, and less than 10% are homozygous for the wild type (fast acetylator) trait. Incorporation of these data into a Monte Carlo modeling framework led to a population distribution of NAT2 activity that was bimodal and associated with considerable variability in each population assessed. The ratio of the median to the first percentile of NAT2 activity ranged from 7 in Caucasians to 18 in the Chinese population. This variability indicates the need for more quantitative approaches (e.g., physiologically based pharmacokinetic [PBPK] modeling) to assess the full distribution of internal dose and adverse responses to aromatic amines and other NAT2 substrates. Polymorphisms in NAT1 are generally associated with relatively minor effects on acetylation function, with Monte Carlo analysis indicating less interindividual variability than seen in NAT2 analysis.

ArylamineN-Acetyltransferases: What We Learn from Genes and Genomes

Arylamine N-acetyltransferases (NATs) are phase II xenobiotic metabolizing enzymes, catalyzing acetyl-CoA-dependent N- and O-acetylation reactions. All NATs have a conserved cysteine protease-like Cys-His-Asp catalytic triad inside their active site cleft. Other residues determine substrate specificity, while the C-terminus may control hydrolysis of acetyl-CoA during acetyltransfer. Prokaryotic NAT-like coding sequences are found in >30 bacterial genomes, including representatives of Actinobacteria, Firmicutes and Proteobacteria. Of special interest are the nat genes of TB-causing Mycobacteria, since their protein products inactivate the anti-tubercular drug isoniazid. Targeted inactivation of mycobacterial nat leads to impaired mycolic acid synthesis, cell wall damage and growth retardation. In eukaryotes, genes for NAT are found in the genomes of certain fungi and all examined vertebrates, with the exception of canids. Humans have two NAT isoenzymes, encoded by highly polymorphic genes on chromosome 8p22. Syntenic regions in rodent genomes harbour two Nat loci, which are functionally equivalent to the human NAT genes, as well as an adjacent third locus with no known function. Vertebrate genes for NAT invariably have a complex structure, with one or more non-coding exons located upstream of a single, intronless coding region. Ubiquitously expressed transcripts of human NAT1 and its orthologue, murine Nat2, are initiated from promoters with conserved Sp1 elements. However, in humans, additional tissue-specific NAT transcripts may be expressed from alternative promoters and subjected to differential splicing. Laboratory animals have been widely used as models to study the effects of NAT polymorphism. Recently generated knockout mice have normal phenotypes, suggesting no crucial endogenous role for NAT. However, these strains will be useful for understanding the involvement of NAT in carcinogenesis, an area extensively investigated by epidemiologists, often with ambiguous results.

The CYP19 TTTA repeat polymorphism is related to the prognosis of premenopausal stage I-II and operable stage III breast cancers

PURPOSE

Given the critical role of the CYP19 gene, encoding aromatase, in estrogen synthesis and the association of the estrogen level with its TTTA repeat polymorphism, the potential influence of this polymorphism on breast cancer survival, and hence management, deserves further study.

METHODS

Genotyping for the CYP19 TTTA repeat polymorphism was performed on 482 stage I-II and operable stage III Taiwanese breast cancer patients. Patients with more than seven TTTA repeats in either allele of CYP19 were defined as having the long allele. We correlated clinical variables and CYP19 genotypic polymorphism with outcome.

RESULTS

In hormone receptor (HR)-positive breast cancers, premenopausal patients with the long allele of the CYP19 polymorphism had a significantly higher overall survival (OS) rate (8-year, 89% versus 68%; p= .003) than those without it. This difference was further demonstrated by a multivariate analysis (OS hazard ratio, 1.53; p= .041). In postmenopausal women or patients with HR-negative breast cancer, there was no significant difference in OS between patients with or without the long allele. In premenopausal women with HR-positive cancers, adequate intensity adjuvant chemotherapy did not achieve a greater OS rate than suboptimal chemotherapy in patients with the long allele, but it resulted in a significantly higher OS rate (p= .011) than suboptimal chemotherapy in women without the long allele.

CONCLUSIONS

The CYP19 TTTA repeat polymorphism is associated with survival in premenopausal women, but not in postmenopausal women, with HR-positive breast cancers. Premenopausal women with the long allele have a greater survival rate and may not gain benefit from adjuvant chemotherapy.

Breast cancer risk is associated with the genes encoding the DNA double-strand break repair Mre11/Rad50/Nbs1 complex

The evolutionarily conserved Mre11-Rad50-Nbs1 (MRN) complex, consisting of proteins encoded by the genes Mre11, Rad50, and Nbs1, was recently shown to play a crucial role in DNA double-strand break (DSB) repair by recruiting the nuclear protein kinase ataxia telangiectasia mutated to DSB sites, leading to activation of this DNA repair network. Given the fact that carriers of defective mutation and polymorphic variants of ataxia telangiectasia mutated are at higher risk of developing breast cancer, we hypothesized a role of the MRN genes in determining breast cancer susceptibility. This hypothesis was examined both in a case control study of 559 breast cancer patients and 1,125 healthy women of single-nucleotide polymorphisms in Mre11, Rad50, and Nbs1 and by the in vivo detection of binding between Mre11 and BRCA1, encoded by the breast cancer susceptibility gene BRCA1. We were also interested in defining whether any association between MRN genes and breast cancer was modified by reproductive risk factors reflecting the level of estrogen exposure or susceptibility to estrogen exposure, as estrogen is known to initiate breast cancer development due to its metabolites causing DSB formation. Support for the hypothesis came from the observations that (a) one single-nucleotide polymorphism in Nbs1 was significantly associated with breast cancer risk, and a trend toward an increased risk of developing breast cancer was found in women harboring a greater number of putative high-risk genotypes of MRN genes (an adjusted odds ratio of 1.25 for each additional putative high-risk genotype; 95% confidence interval, 1.10-1.44); (b) this association between risk and the number of putative high-risk genotypes was stronger and more significant in women thought to be more susceptible to estrogen, i.e., those with no history of full-term pregnancy, those older (>or=26 years of age) at first full-term pregnancy, or those having had fewer (<2) full-term pregnancies; the risk effect conferred by harboring a higher number of high-risk genotypes of MRN genes was more significant in women without a history of breast feeding; and (c) Mre11 and BRCA1 were shown to form a complex in vivo, and this interaction was increased by irradiation. This study supports the role of the MRN pathway in breast cancer development, further strengthening the suggestion that mechanisms regulating DSB repair may play a mutator role driving breast cancer pathogenesis.

Polymorphism of cytosolic serine hydroxymethyltransferase, estrogen and breast cancer risk among Chinese women in Taiwan

Cytosolic serine hydroxymethyltransferase (cSHMT) is key to intersection of folate-metabolic pathway, participating in the pyrimidine synthesis for DNA repair. Based on the hypothesis that variants of the cSHMT C1420T together with methionine synthase (MS A2756G) and 5,10-methylenetetrahydrofolate reductase (MTHFR C677T and A1298C) are associated with breast cancer, we performed a multigenic case-control study of the effects to breast cancer risk of four polymorphisms of folate-metabolizing genes against duration of estrogen exposure. Support of our hypothesis came from the following observations: (i) Allelic frequency of cSHMT C1420T was higher in the controls than in the cases, manifesting a 0.56-fold risk reduction in breast cancer (95%CI = 0.39-0.80); and this association was more significant in those women are susceptible to time of estrogen exposure. (ii) A joint effect of the cSHMT and MS polymorphisms significantly reduced susceptibility to breast cancer (aOR = 0.55; 95%CI = 0.34-0.88). (iii) There was a trend toward a reduced risk of breast cancer in women carrying a greater number of putative low-risk genotypes (Ptrend = 0.048). (iv) This synergistic effects on risk reduction was significantly interacted with length of estrogen exposure, exhibiting a longer time of estrogen exposure (> or =30 years), menarche-to-FFTP interval (>11 years), age at the first full-term pregnancy (< or =25 years), and body mass index (< or =24). In conclusion, our study provides support to account for the preferential role of cSHMT polymorphism to lower risk of female breast cancer, and such reduced risk would be more significant in carriers with the polymorphisms of MS and MTHFR genes.

A meta-analysis of the association of N-acetyltransferase 2 gene (NAT2) variants with breast cancer

The N-acetyltransferase 2 gene (NAT2) product is an enzyme important in carcinogen metabolism via activation and detoxification pathways. Therefore, NAT2 variants may represent underlying susceptibility to breast cancer. Because a number of studies of the association of NAT2 with breast cancer have been published, the authors performed a meta-analysis. They extracted all relevant data to examine evidence for a main effect (i.e., the effect in a model that does not include any interactions) of NAT2 phenotype and genotype on breast cancer risk. They summarized the evidence for modification by smoking and meat intake, sources of exposure to aromatic and heterocyclic amines, respectively, which are metabolized by NAT2. The authors identified seven studies that measured NAT2 phenotype and 20 studies that deduced phenotype via genotyping. They found no evidence for heterogeneity (Cochran's Q statistic p=0.74) and no statistically significant increased risk from NAT2 acetylation (slow/rapid) for breast cancer (summary odds ratio=1.02, 95% confidence interval: 0.95, 1.08). These results suggest that there is no overall association between the NAT2 slow- or rapid-acetylation phenotype and breast cancer risk. However, some evidence suggests that smoking may modify this association.

NAT2 fast acetylator genotype is associated with an increased risk of colorectal cancer in Taiwan

In Taiwan, colorectal cancer has one of the highest rates of increased incidence in the past two decades. Heterocyclic amines from dietary cooked meats are metabolically activated by NAT2 (N-acetyltransferase 2), which are associated with colorectal cancer incidence. Thus, the NAT2 fast acetylator genotype may be associated with colorectal cancer risk. However, the association between the NAT2 genotype and colorectal cancer risk is not clearly understood. We conducted a study with 244 primary colorectal cancer cases and 299 cancer-free healthy control subjects to verify the association of NAT2 polymorphisms with the risk of Taiwanese colorectal cancer. Our data showed that subjects with the NAT2 W/W homozygous genotype had a 1.63-fold increased risk of colorectal cancer compared with those with the Mx/Mx slow acetylator genotype (95 percent confidence interval, 1.03-2.58); however, no risk was found in the W/Mx heterozygous and Mx/W+W/W fast acetylator genotypes. Being stratified by gender factors, the colorectal cancer risk in females with homozygous W/W or Mx/W+W/W fast acetylators increased 2.47-fold and 2.13-fold compared with those with the Mx/Mx slow acetylator genotype (95 percent confidence interval, 1.27-4.82 for W/W genotype; 95 percent confidence interval, 1.17-3.89 for Mx/W+W/W genotype); however, the risk of the NAT2 genotype and colorectal cancer was not observed in males. Collectively, patients with the NAT2 fast acetylator genotype were more prone to colorectal cancer and reflected the possibility that exposure to heterocyclic amines may contribute to colorectal cancer development in Taiwan, especially in Taiwanese females.

Active and passive smoking, IL6, ESR1, and breast cancer risk

We evaluated the association between smoking and risk of breast cancer in non-Hispanic white (NHW) and Hispanic or American Indian (HAI) women living in the Southwestern United States. Data on lifetime exposure to active and passive smoke data were available from 1527 NHW cases and 1601 NHW controls; 798 HAI cases and 924 HAI controls. Interleukin 6 (IL6) and Estrogen Receptor alpha (ESR1) polymorphisms were assessed in conjunction with smoking. Pack-years of smoking (>or=15) were associated with increased risk of pre-menopausal breast cancer among NHW women (OR 1.6, 95% CI 1.1-2. 4). Passive smoke increased risk of pre-menopausal breast cancer for HAI women (OR 1.9, 95% CI 1.1-3.1 everyone; OR 2.3, 95% CI 1.2-4.5 nonsmokers). HAI pre-menopausal women who were exposed to 10+ h of passive smoke per week and had the rs2069832 IL6 GG genotype had over a fourfold increased risk of breast cancer (OR 4.4, 95% CI 1.5-12.8; P for interaction 0.01). Those with the ESR1 Xba1 AA genotype had a threefold increased risk of breast cancer if they smoked>or=15 pack-years relative to non-smokers (P interaction 0.01). These data suggest that breast cancer risk is associated with active and passive smoking.

Influence of CYP1A1, CYP2E1, GSTM3 and NAT2 genetic polymorphisms in oral cancer susceptibility: results from a case-control study in Rio de Janeiro

Xenobiotic metabolizing enzymes are involved in the detoxification of many carcinogens and may be important in modulating cancer susceptibility. CYP1A1, CYP2E1, GSTM3, and NAT2 polymorphisms were determined in peripheral blood DNA of 231 oral cancer patients and 212 hospital controls in Rio de Janeiro, Brazil, using the PCR-RFLP technique. NAT2 polymorphism distribution was different between cases and controls (P=0.035), with an overrepresentation of NAT2( *)11 mutant allele in controls. Risk analysis showed that NAT2 4/4 individuals (OR=1.95, 95% CI=1.05-3.60) and combined GSTM3 and NAT2 heterozygotes (OR=1.94, 95% CI=1.04-3.66) were at increased oral cancer risk. No statistically significant association was observed for CYP1A1 and CYP2E1 polymorphisms. Our results suggest that NAT2 polymorphism, alone or combined with GSTM3, may modulate susceptibility to oral cancer in Rio de Janeiro.

Lack of association between endometriosis and N-acetyl transferase 1 (NAT1) and 2 (NAT2) polymorphisms in a Japanese population

OBJECTIVE

We investigated the association between endometriosis and polymorphisms in the N-acetyltransferase 1 (NAT1) and N-acetyltransferase 2 (NAT2) genes in a Japanese population, having previously demonstrated a positive association with NAT2 polymorphisms in a UK population.

METHODS

Genotyping for NAT1 alleles *3, *4, *10, and *11, and NAT2 alleles *4, *5A, *5B, *5C, *6A, and *7B was performed using polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) and allele-specific PCR (AS-PCR) analysis in 145 ethnically Japanese, endometriosis patients and 182 controls. The NAT1 and NAT2 allele and genotype frequencies were compared in cases and controls using the Fisher exact test.

RESULTS

No significant differences between cases and controls were observed in the frequencies of the NAT1 and NAT2 alleles (P = .13; P = .91) and genotypes (P = .24; P = .79), and the NAT2 acetylation phenotypes (P = .46). Dividing the cases into a subgroup, consisting of women with severe disease only (n = 80), had no effect on the results.

CONCLUSION

The distribution of NAT1 and NAT2 allele and genotype frequencies were not significantly different between Japanese cases and controls. Our findings suggest that polymorphisms in NAT1 and NAT2 are unlikely to be associated with an increased risk of endometriosis in the Japanese population.

Cumulative genetic defects in carcinogen metabolism may increase breast cancer risk (The Netherlands)

Variants in the metabolic genes NAT1, NAT2, GSTM1 or GSTT1, may cause differences in individual detoxifying capacity of possible carcinogens. We examined the cumulative effect of putative at risk genotypes on breast cancer risk and we examined the extent to which these polymorphisms modify the association between smoking and breast cancer. A case cohort study was conducted in the DOM cohort with 676 breast cancer cases and a random sample of 669 individuals. No effect of the NAT1, NAT2 or GSTM1 genotypes on breast cancer risk was observed. However, women with GSTT1 null genotype had a 30% increased breast cancer risk compared to women with GSTT1 present (RR = 1.30 (95% confidence interval (CI) 1.04-1.64)). Smoking did not influence breast cancer risk nor did genetic variations in NAT1, NAT2 or GSTM1 in combination with smoking. Compared to women who never smoked with GSTT1 present, women with GSTT1 null genotype and who formerly smoked showed an increased breast cancer risk (RR = 2.55 (95% CI 1.10-5.90)), but current smokers who smoked 20 cigarettes or more per day did not (RR = 1.06 (95% CI 0.51-2.18)). Increasing numbers of putative at risk genotypes increased breast cancer risk in a dose dependent manner (p for trend 0.01). The risk was more than doubled in women with all four risk genotypes, RR = 2.45 (95% CI 1.24-4.86), compared to women with zero putative at risk genotypes. In conclusion, the results of this study suggest that presence of three or more putative at risk genotypes increases breast cancer risk.

NAT2 slow acetylator genotype as an important modifier of breast cancer risk

N-acetyltransferase 2 (NAT2) is a polymorphic enzyme participating in the metabolism of numerous pharmaceutical drugs and carcinogens found in tobacco smoke and diet. The NAT2 gene is highly polymorphic and several different allelic variants exist that determine the acetylator phenotype. In the course of our case-control study, we developed a new method based on fluorogenic allele-specific probes for analyzing the C282T and T341C polymorphisms of the NAT2 gene in 483 Finnish breast cancer patients and 482 healthy population controls. The slow NAT2 acetylation capacity-associated genotypes posed a somewhat increased overall breast cancer risk (odds ratio [OR], 1.32; 95% confidence interval [CI], 1.01-1.73). This association was found to be confined to the advanced (stage III or IV) breast cancer (OR, 2.60; 95% CI, 1.29-5.24). When stratified by smoking habits, women who had smoked <5 pack-years and carried a NAT2 slow acetylator genotype were at a 2.6-fold (OR, 2.55; 95% CI, 1.01-6.48) risk of breast cancer. Moreover, women with the NAT2 slow acetylator genotype and low body mass index (BMI) (<25.4 kg/m2) were at somewhat increased risk of this malignancy (OR, 1.60; 95% CI, 1.07-2.39). Our results therefore suggest that NAT2 slow acetylator genotype may be an important modifier of environmentally induced breast cancer risk in Finnish women.

Breast cancer risk associated with genotypic polymorphism of the mitosis-regulating geneAurora-A/STK15/BTAK

Aneuploidy, an abnormal number of chromosomes, is relatively common and occurs early in breast cancer development. This observation supports a breast tumorigenic contribution of mechanisms responsible for maintaining chromosome number stability in which centrosomes play an essential role. We therefore speculated that the Aurora-A/STK15/BTAK gene, implicated in the regulation of centrosome duplication, may be associated with breast tumorigenesis. To test this hypothesis, we conducted a case-control study of 709 primary breast cancer patients and 1,972 healthy controls, examining single-nucleotide polymorphisms (SNPs), including a suggested functional Phe31Ile SNP, in Aurora-A. We were also interested in knowing whether any association between Aurora-A and breast cancer was modified by reproductive risk factors reflecting susceptibility to estrogen exposure. Our hypothesis is that, since estrogen is known to promote breast cancer development via its mitogenic effect leading to malignant proliferation on breast epithelium and since Aurora-A is involved in regulating mitosis, the discovery of a joint effect between the Aurora-A genotype and reproductive risk factors on cancer risk might yield valuable clues to the association of breast tumorigenesis with estrogen. Support for this hypothesis came from the following observations. (i) Two SNPs in Aurora-A were significantly associated with breast cancer risk (p < 0.05). (ii) Haplotype analyses, based on different combinations of multiple SNPs in Aurora-A, revealed a strong association with breast cancer risk; interestingly, the genotypic distribution of the suggested functional Phe31Ile SNP was not significantly different between breast cancer patients and controls, but the specific haplotype containing the putative at-risk Ile allele was more common in patients. (iii) This association between risk and putative high-risk genotypes was stronger and more significant in women thought to be more susceptible to estrogen, i.e., those with a longer interval between menarche and first full-term pregnancy. (iv) The protective effect conferred by a history of full-term pregnancy was significant only in women with a putative low-risk genotype of Aurora-A. Our study provides new findings supporting the mutator role of Aurora-A in breast cancer development, suggesting that breast cancer could be driven by genomic instability associated with variant Aurora-A, the tumorigenic contribution of which could be enhanced as a result of increased mitosis due to estrogen exposure.

N-acetyltransferase 2 (NAT2) genotypes, cigarette smoking, and the risk of breast cancer

N-acetyltransferases (NATs) are important catalytic enzymes that metabolize carcinogenic arylamines. NAT2 genotype might modify the role of cigarette smoking, a source of arylamine exposure, in breast cancer. We conducted a nested case-control study to investigate the association between NAT2 genotype, smoking and breast cancer risk among women (110 cases, 113 matched controls) from the CLUE II cohort in Washington County, MD. Compared to women with the slow acetylator genotype, the main effects odds ratios (OR) for NAT2 were 1.4 for the intermediate acetylator genotype (95% confidence limits (CL) 0.7, 2.7) and 3.6 for the homozygous rapid acetylator genotype (95% CL 1.1, 11.4) (P for trend = 0.05). Smoking was associated in the direction of increased breast cancer risk in slow acetylators (e.g., >15 pack-years versus never smokers OR 2.0; 95% CL 0.7, 5.8) but not in rapid acetylators. These associations were not statistically significant in the total study population, but a statistically significant interaction between smoking and NAT2 acetylator status was present in postmenopausal women. The main effect of NAT2 in the direction of increased risk suggests that exposures to NAT2-activated carcinogens other than cigarette smoke may be important in this study population. The results for smoking were consistent with an inactivation role for NAT2 in breast cancer.

N-acetyltransferase (NAT2) polymorphism and breast cancer susceptibility: a lack of association in a case-control study of Turkish population

Increased exposure to environmental carcinogens, including several aromatic and heterocyclic amines (HAs), is suspected to be one factor contributing to incidence of breast cancer. The N-acetyltransferase 2 (NAT2) acetylation polymorphism have been associated with a number of drug-induced toxicities and cancer in various tissues, resulting from decreased capacity to activate/deactivate several aromatic amine, hydrazine drugs, as well as HA carcinogens. Ethnic differences exist in NAT2 genotype frequencies, which maybe a factor in cancer incidence. Our present case-control study in Turkey was performed to explore the association between NAT2 genetic polymorphism and individual susceptibility to breast cancer. The NAT2 genotypes (*4, *12A, *5A, *5B, *5C, *6, *7) were determined using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay in 84 breast cancer patients and 103 healthy controls, and 50% and 56.3%, respectively, were found to be slow acetylator genotypes. There was no significant difference in risk for breast cancer development among patients with rapid and slow acetylators, with adjusted odds ratio 0.78 (95% confidence interval 0.44 to 1.38). Also, risk was not affected by different variables. To our knowledge, this is the first genetic study on the association of NAT2 genotypes with breast cancer in the TUrkish population, and this finding showed that NAT2 polymorphism does not play an important role in breast cancer risk of Turkish women by altering the capacity in deactivation of environmental carcinogens, even though small sample size and wide confidence interval.

Breast cancer risk associated with genotype polymorphism of the catechol estrogen-metabolizing genes: A multigenic study on cancer susceptibility

Estrogen has been suggested to trigger breast cancer development via an initiating mechanism involving its metabolite, catechol estrogen (CE). To examine this hypothesis, we carried out a multigenic case-control study of 469 incident breast cancer patients and 740 healthy controls to define the role of important genes involved in the different metabolic steps that protect against the potentially harmful effects of CE metabolism. We studied the 3 genes involved in CE detoxification by conjugation reactions involving methylation (catechol-O-methyltransferase, COMT), sulfation (sulfotransferase 1A1, SULT1A1), or glucuronidation (UDP-glucuronosyltransferase 1A1, UGT1A1), one (manganese superoxide dismutase, MnSOD) involved in protection against reactive oxidative species-mediated oxidation during the conversion of CE-semiquinone (CE-SQ) to CE-quinone (CE-Q), and 2 of the glutathione S-transferase superfamily, GSTM1 and GSTT1, involved in CE-Q metabolism. Support for this hypothesis came from the observations that (i) there was a trend toward an increased risk of breast cancer in women harboring a greater number of putative high-risk genotypes of these genes (p < 0.05); (ii) this association was stronger and more significant in those women who were more susceptible to estrogen [no history of pregnancy or older (> or =26 years) at first full-term pregnancy (FFTP)]; and (iii) the risks associated with having one or more high-risk genotypes were not the same in women having experienced different menarche-to-FFTP intervals, being more significant in women having been exposed to estrogen for a longer period (> or =12 years) before FFTP. Furthermore, because CE-Q can attack DNA, leading to the formation of double-strand breaks (DSB), we examined whether the relationship between cancer risk and the genotypic polymorphism of CE-metabolizing genes was modified by the genotypes of DSB repair genes, and found that a joint effect of CE-metabolizing genes and one of the two DSB repair pathways, the homologous recombination pathway, was significantly associated with breast cancer development. Based on comprehensive CE metabolizing gene profiles, our study provides support to the hypotheses that breast cancer can be initiated by estrogen exposure and that increased estrogen exposure confers a higher risk of breast cancer by causing DSB to DNA.

Thoughts on Individualizing Hormone Replacement Therapy Based on the Postmenopausal Health Disparities Study Data

BACKGROUND

This study presents an approach that can be used to address the controversy about the long-term risks and benefits of hormone replacement therapy (HRT).

METHODS

Categories of estradiol (E(2)) levels based on the mean and standard deviation (SD) in postmenopausal women not treated with HRT were created. E(2) levels achieved in women treated with oral or patch replacement therapy were examined. In the application of this method, data from the Postmenopausal Health Disparities Study were used because identical E(2) assay methods were used for all postmenopausal women in the study population.

RESULTS

The findings demonstrated that approximately 42% of HRT-treated women had E(2) levels less than the mean E(2) level plus 1 SD in the controls (37 pg/ml). In contrast, approximately 11% had E(2) levels greater than the mean E(2) level plus 6 SD in the controls (126 pg/ml). Menopausal vasomotor and vaginal symptoms decreased ( p < 0.06) in increasing control-based E(2) categories. Levels of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were significantly correlated with the E(2) control-based categories (both p = 0.000). When hormone variables and other variables (e.g., moderate alcoholic beverage consumption and bilateral ovariectomy) known to be determinants of E(2) levels in postmenopausal women not treated with HRT were included in the model for oral or patch HRT-treated women, 51.1% of the variability in the control-based E(2) categories was explained when menopause duration, use of oral as opposed to patch therapy, body mass index (BMI), scores for medical compliance, and being white entered the equation as statistically significant predictors.

CONCLUSIONS

First, there is substantial variability in E(2) concentrations achieved with conventional oral and patch HRT. Second, various factors that are statistically significant predictors of response categories have been identified. Third, race/ethnic group plays a role in the response to HRT. Finally, the demonstration of variable responses to HRT and the application of the categorization paradigm presented will be useful in resolving the controversy about the risks and benefits of conventional HRT.

N-acetyltransferase (NAT1, NAT2) and glutathione S-transferase (GSTM1, GSTT1) polymorphisms in breast cancer

To evaluate the potential association between NAT1/NAT2 polymorphisms and breast cancer, a case-control study was conducted in Korean women (254 cases, 301 controls). NAT1 *4/*10 genotype (42%) was the most common NAT1 genotype in this Korean population. The frequencies of slow, intermediate and rapid NAT2 acetylator genotype were 16, 39 and 44% in cases and 16, 42 and 42% in controls. Neither NAT1 rapid (homozygous or heterozygous NAT1 *10) (OR=1.2, 95% CI=0.8-1.9) nor NAT2 rapid acetylator genotype (OR=1.2, 95% CI=0.8-1.7) showed significant association with breast cancer risk. Although the risk of NAT2 rapid acetylator genotype in postmenopausal women (OR=1.4, 95% CI=0.7-2.8) was higher than that in premenopausal women (OR=1.1, 95% CI=0.7-1.7), those were not statistically significant. However, combinations of NAT1, GSTM1 and GSTT1 genotypes showed a significant linear gene-dosage relationship with breast cancer (p for trend=0.04) and those women with NAT2 rapid acetylator and both GSTM1 and GSTT1 null genotypes were at the elevated risk (OR=3.1, 95% CI=1.0-9.1). These results suggest that genetic polymorphisms of NAT1 and NAT2 have no independent effect on breast cancer risk, but they modulate breast cancer risk in the presence of GSTM1 and GSTT1 null genotypes.

NAT2 slow acetylation and GSTM1 null genotypes may increase postmenopausal breast cancer risk in long-term smoking women

N-acetyltransferase (NAT) 1 and 2 and glutathione S-transferase (GST) M1 and T1 are phase II enzymes that are important for activation and detoxification of carcinogenic heterocyclic and aromatic amines, as present in cigarette smoke. We studied whether genetic polymorphisms in these genes modifies the relationship between smoking and breast cancer. A nested case-control study was conducted among participants in a Dutch prospective cohort. Breast cancer cases (n=229) and controls (n=264) were frequency-matched on age, menopausal status and residence. Compared to never smoking, smoking 20 cigarettes or more per day increased breast cancer risk statistically significant only in postmenopausal women [odds ratio (OR)=2.17; 95% confidence interval (CI) 1.04-4.51]. Neither NAT1 slow genotype, or GSTT1 null genotype, alone or in combination with smoking, affected breast cancer risk. However, compared to individuals with rapid NAT2 genotype, women with the very slow acetylator genotype (NAT2*5), who smoked for 20 years showed an increased breast cancer risk (OR=2.29; 95% CI 1.06-4.95). Similarly, the presence of GSTM1 null genotype combined with high levels of cigarette smoking (OR=3.00; 95% CI 1.46-6.15) or long duration (OR=2.53; 95% CI 1.24-5.16), increased rates of breast cancer. The combined effect of GSTM1 null genotype and smoking high doses was most pronounced in postmenopausal women (OR=6.78; 95% CI 2.31-19.89). In conclusion, our results provide support for the view that women who smoke and who have a genetically determined reduced inactivation of carcinogens (GSTM1 null genotype or slow NAT2 genotype (especially very slow NAT2 genotype)) are at increased risk of breast cancer.

Hormone replacement therapy and menopause: a review of randomized, double-blind, placebo-controlled trials

Hormone replacement therapy (HRT) is frequently prescribed to healthy women to ameliorate menopausal symptoms. HRT is used long term (> or = 1 year) to prevent chronic disease in older women. The objective of this study was to review the benefits and risks of HRT and studies of menopause or HRT in Taiwan via a MEDLINE search. Recommendations are provided for future HRT research in Taiwan. Randomized, double-blind, placebo-controlled clinical trials are considered the gold standard of scientific evidence. A MEDLINE literature search (January 1966-July 2002) identified 23 papers on trials (> or = 1 year) that met the inclusion criteria. The results showed that various HRT regimens used for more than 1 year caused more harm than good in healthy menopausal women and that there was no benefit for women with coronary artery disease, Alzheimer's disease, hysterectomy, hysterosalpingo-oophorectomy, and ischemic stroke. None of this research was conducted in Taiwan. A MEDLINE search using the key words "estrogen replacement therapy and menopause in Taiwan" identified 16 studies. There was only one, short-term, HRT trial. No evidence suggested benefits from long-term HRT in menopausal women in Taiwan.

Environmental risk factors for breast cancer among African-American women

There are few unequivocably established environmental carcinogens for breast cancer in women. Nevertheless, environmental factors are believed to explain much of the international variation in breast cancer risk and possibly differences among racial/ethnic groups. Along with lifestyle, some adverse exposures may be higher in minority racial/ethnic groups and in underserved populations that experience higher ambient contamination. Associations have been found between environmental agents and breast cancer in subgroups of women who can be identified by common susceptibility traits as well as by timing of exposures at certain milestones of reproductive life. Susceptibility can be defined by social, environmental, and genetic modalities-factors that may predominate in certain racial/ethnic groups but that also transcend racial/ethnic boundaries. For example, genes involved in transcription and estrogen metabolism have rapid variants that are more prevalent among African-Americans, yet risk accompanying metabolic changes from these genes will prevail in all racial/ethnic groups. Lack of reliable exposure assessment remains a principal obstacle to elucidating the role of environmental exposures in breast cancer. Resources must be identified and consolidated that will enable scientists to improve exposure assessment and to assemble studies of sufficient size to address questions regarding exposure, susceptibility, and vulnerability factors in breast cancer. Breast cancer studies should be expanded to examine combinations of chemicals as well as competing or complementary exposures such as endogenous hormones, dietary intake, and behavioral factors.

GSTT1 null genotype increases risk of premenopausal breast cancer

The NAT2, GSTM1 and GSTT1 genes are known candidate cancer susceptibility markers and have been investigated in breast cancer susceptibility with conflicting results. We conducted a case-control study to investigate the role of NAT2, GSTM1 and GSTT1 in premenopausal breast cancer. Women with the GSTT1 null genotype were found to have a significant 3.15-fold increased risk of breast cancer (95% CI = 1.7-5.8), while GSTM1 and NAT2 genotypes were not associated with breast cancer risk. Our results suggest that the GSTT1 null genotype may play a role in early onset breast cancer.

Association of vitamin D receptor gene polymorphism with sporadic breast cancer in Taiwanese patients

PURPOSE

Previous reports have suggested that polymorphism in the vitamin D receptor (VDR) gene is associated with sporadic breast cancer, but there is controversy among different authors and ethnic groups. The purpose of this study was to determine whether polymorphism in the VDR gene might also influence breast cancer risk in Taiwan, a country with a low incidence of breast cancer.

METHODS

Polymorphisms in the end of the VDR gene were genotyped for 34 Taiwanese women with sporadic breast cancer, 46 with benign breast tumors and 169 cancer-free female cohort controls.

RESULTS

The ApaI, TaqI, and BsmI polymorphisms in the 3' end of the VDR gene were associated with breast cancer risk, with a trend for increasing risk with increased numbers of BsmI B alleles and ApaI AA genotypes. When the allele frequencies of BsmI polymorphism were compared among the three populations, a significant difference was observed (chi2 = 13.684, df = 4, p = 0.0084). The OR of the Aa genotype was 0.333 (95% CI = 0.1 14-0.978) and that of the aa genotype was 0.515 (95% CI = 0.190-1.398). These data indicate that the AA genotype may be associated with an increased risk of breast cancer, while the Aa genotype tends to be associated with decreased risk. The TaqI polymorphism was not associated with breast cancer risk in this study.

CONCLUSION

These results suggest that polymorphic variation in or near the 3' end of the VDR gene may influence breast cancer risk in Taiwanese women and justifies further investigation of the role of VDR for sporadic breast cancer in low-incidence areas. These findings also should help when designing targeted therapy.

Association of DNA-protein crosslinks and breast cancer

This study examined the possible effect of cytochrome P450 (CYP1A1), glutathione S-transferase (GSTM1 and T1) and N-acetyltransferases 2 (NAT2) polymorphisms on DNA-protein crosslinks (DPC) formation in the white blood cells of breast cancer patients, and assessed the levels of DPC detected. Sixty cases of breast cancer were examined, all involving women diagnosed with primary, histopathologically confirmed breast cancer at the Chinese Medical College Hospital in central Taiwan. Additionally, 60 healthy women without breast cancer were selected as a control group, matched by age, cigarette smoking habits, and history of breast cancer among first-degree relatives. Known risk factors for breast cancer, including menarche before 13 years of age (OR=3.2; CI, 1.1-9.5), no history of breast-feeding (OR=4.7; CI, 1.5-14.4) and use of oral contraceptives (OR=9.1; CI, 2.8-29.8), were found to be significantly associated with breast cancer. For the CYP1A1 MspI polymorphism, 16.7 and 18.3% of cases and controls, respectively contained both alleles with the MspI restriction fragment length polymorphism (RFLP). Regarding the NAT2 allele, 25.0 and 21.7% of cases and controls carried slow genotypes. For GSTM1 and GSTT1, 56.7 and 45.0% of cases, as well as 58.3 and 43.3% of controls, contained the null genotype. Meanwhile, chi(2)-tests found no significant differences between the groups. After controlling for confounders such as cigarette smoking and family history of breast cancer, the DPC value of the case group significantly exceeded that of the control group (1.62% versus 0.98%, P<0.001). In conclusion, our findings were inconsistent with those of previous studies that showed polymorphism genes (CYP1A1, NAT2, GSTM1 and GSTT1) were associated with cancer risk. However, this study indicated that genotypic variants of these polymorphisms did not elevate the risk for breast cancer, individually or interactively. Additionally, this investigation represents the first description of the use of DPC as a biomarker to assess the level of DNA damage of breast cancer patients. Our data suggest that the DPC method is a useful tool for detecting DNA damage, and DPC formation may be associated with the induction of breast cancer.

Genes other than BRCA1 and BRCA2 involved in breast cancer susceptibility

This review focuses on genes other than the high penetrance genes BRCA1 and BRCA2 that are involved in breast cancer susceptibility. The goal of this review is the discovery of polymorphisms that are either associated with breast cancer or that are in strong linkage disequilibrium with breast cancer causing variants. An association with breast cancer at a 5% significance level was found for 13 polymorphisms in 10 genes described in more than one breast cancer study. Our data will help focus on the further analysis of genetic polymorphisms in populations of appropriate size, and especially on the combinations of such polymorphisms. This will facilitate determination of population attributable risks, understanding of gene-gene interactions, and improving estimates of genetic cancer risks.

Smoking (active and passive) and breast cancer: epidemiologic evidence up to June 2001

The first generation of studies evaluating the association between exposure to tobacco smoke and breast cancer merely compared active to nonactive smokers, with varying degrees of detail in the definition of active smoking. With rare exceptions, studies of this kind failed to show an effect of smoking on breast cancer risk. However, such analysis is probably insufficient. The most recent reports on the smoking-breast cancer connection have two characteristics. Some have separated women exposed to passive smoking from those nonexposed to either active or passive smoke. Other reports have focused on factors that modify the effect of smoking on breast cancer incidence, such as genetic markers or hormone receptors. A minority of reports combines these two characteristics. This review addresses the epidemiologic evidence for a link between smoking and breast cancer and discusses the implications of this evidence for future studies.

Leukemia inhibitory factor decreases the arylamine N-acetyltransferase activity in human cumulus granulosa cells

PURPOSE

To evaluate the activities of acetyl coenzyme A (AcCoA):arylamine N-acetyltransferase (NAT) of intact cumulus granulosa cells and the role of leukemia inhibitory factor (LIF) upon their NAT activities.

METHODS

Thirty women accepted controlled ovarian hyperstimulation (COH) and oocyte retrievals. Human cumulus granulosa cells were obtained during oocyte retrievals. Using 2-aminofluorene (2-AF) and p-aminobenzoic acid (PABA) as substrates, NAT activity of all samples was determined by high pressure liquid chromatography. After the incubation with different time and concentrations of 2-AF, PABA, and LIF, 2-acetyl-aminofluorene (2-AAF) and N-acetyl-PABA (N-Ac-PABA) were measured.

RESULTS

After incubation with 2.812, 5.625, 11.25, and 22.5 microM of 2-AF/PABA, their product concentrations (2-AAF/N-Ac-PABA) were 0.42/0.32, 0.76/0.58, 1.29/1.04, and 1.94/1.26 nmol/10(6) cells, respectively. After 6, 12, 18, and 24 h incubation with 11.25 microM of 2-AF/PABA, their product concentrations were 0.19/0.12, 0.56/0.4, 0.98/0.79, and 1.3/1.0 nmol/10(6) cells, respectively. After incubation with 0, 5, and 50 microM of LIF, the 2-AAF/N-Ac-PABA concentrations were 0.98/0.80, 0.70/0.52, and 0.49/0.30 nmol/10(6) cells, respectively.

CONCLUSION

Intact human cumulus granulosa cells could acetylate arylamine carcinogen (2-AF) and noncarcinogens drug (PABA). LIF decreased the NAT activities. It provides a model for monitoring the effects of COH and LIF upon the oocytes.

Kinetics of acetyl coenzyme A: arylamine N-acetyltransferase from human cumulus cells

PURPOSE

N-acetyltransferase (NAT) activity is involved in the detoxification of exogenous amines. We aimed to evaluate the kinetics of acetyl coenzyme A (AcCoA): arylamine NAT for human cumulus cells.

METHODS

Thirty infertile women who were undergoing controlled ovarian hyperstimulation (COH) and oocyte retrievals were recruited. Human cumulus cells were obtained during oocyte retrievals. Using 2-aminofluorene (2-AF) and p-aminobenzoic acid (PABA) as substrates, NAT activity and Michaelis-Menten kinetics constants of all samples were determined by using high-pressure liquid chromatography.

RESULTS

There were 6 rapid, 10 intermediate, and 14 slow acetylators. 2-AF-NAT and PABA-NAT activities were 0.97 +/- 0.74 and 0.89 +/- 0.77 nmol/min/mg protein, respectively. Km/Vmax of rapid and slow acetylators for 2-AF were (161 +/- 55)/(15.6 +/- 2.9) and (27.8 +/- 11.4)/(2.6 +/- 0.9), respectively. Km/Vmax of rapid and slow acetylators for PABA were (104 +/- 36)/(13.2 +/- 2.8) versus (20.0 +/- 10)/(2.0 +/- 0.7), respectively. Compared to slow acetylators, the rapid acetylators exhibited higher Km/Vmax values for 2-AF (5.8-/6-fold) and PABA (6-/6.6-fold), respectively.

CONCLUSION

Human cumulus could acetylate arylamine carcinogen (2-AF) and noncarcinogen drug (PABA). Higher percentage of rapid acetylators established in the cumulus during COH. It provides a model for monitoring the effects of pollution or carcinogenesis upon the oocyte during COH and oocyte retrievals.