Lack of Association Between NOS3 Glu298Asp and Breast Cancer Risk: a Case–ontrol Study
Hospital Universitario Virgen del Rocío, Hispalis, Andalusia, SpainBreast Cancer Research and Treatment (Impact Factor: 3.94). 01/2007; 100(3):331-3. DOI: 10.1007/s10549-006-9258-0
Nitric oxide (NO) plays a central role in the physiololgy and pathology of diverse tissues. Different studies provide data suggesting that the endothelial cell nitric oxide synthase (NOS3) expression in peritumoral microvessels might be a prognostic indicator in breast cancer patients. However, the putative contribution of common NOS3 germline variants to breast cancer risk remained unknown. A recent work comprising 269 breast cancer patients and 244 controls suggested that NOS3 Glu298Asp polymorphism is associated to breast cancer risk (OR=1.9). We performed an independent analysis of these results in 440 unrelated patients and 321 controls from Spanish population. Although our study was 90% powered to detect ORs >/=1.55, did not find any significant difference in the Glu298Asp allele distribution between cases and controls (P > 0.42). These putative reasons for this result are discussed.
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ABSTRACT: NOS3 and MPO genes encode endothelial nitric oxide synthase and myeloperoxidase (MPO), respectively, which generate nitric oxide and reactive oxygen species. Because cigarette smoking generates reactive species, we hypothesized that NOS3 and MPO polymorphisms could influence susceptibility to breast cancer, particularly among smokers. We examined the associations between NOS3 Glu298Asp and MPO G-463A polymorphisms and breast cancer risk by cigarette smoking among post-menopausal women in the American Cancer Society's Cancer Prevention Study II Nutrition Cohort. Included in this analysis were 502 women who provided blood samples and were diagnosed with breast cancer between 1992 and 2001 and 505 cancer-free controls who were matched to the cases by age, race/ethnicity and date of blood donation. Genotyping for NOS3 and MPO was performed using TaqMan, and unconditional logistic regression was used to compute odds ratios (ORs) and 95% confidence intervals (CIs). No statistically significant relationships were found between NOS3 and MPO genotypes and breast cancer risk. When considering smoking, variant NOS3 genotypes (GT and TT) were significantly associated with reduced breast cancer risk among never smokers (OR = 0.67, 95% CI = 0.45-0.99), but were associated with higher risk among ever smokers (OR = 1.59, 95% CI = 1.05-2.41) and 2-fold increase in risk for those who smoked >10 cigarettes per day (OR = 2.19, 95% CI = 1.21-3.97). NOS3 genotypes appeared to be associated with risk of post-menopausal breast cancer among smokers, supporting the hypothesis that subgroups of women based upon genetic profiles may be at higher risk of breast cancer when exposed to tobacco smoke.
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ABSTRACT: Oxidative stress resulting from excess reactive oxygen species and/or deficiencies in antioxidant capabilities may play a role in breast cancer etiology. In a nested case-control study of postmenopausal women (505 cases and 502 controls) from the American Cancer Society Prevention II Nutrition Cohort, we examined relationships between breast cancer risk and genetic polymorphisms of enzymes involved in the generation and removal of iron-mediated reactive oxygen species. Using unconditional logistic regression, genetic variations in Nrf2 (11108C>T), NQO1 (609C>T), NOS3 (894G>T), and HO-1 [(GT)(n) dinucleotide length polymorphism] were not associated with breast cancer risk in a multivariate model. A significant dose trend (P trend = 0.04), however, was observed for total number of putative "at-risk" alleles (Nrf T, NQO1 T, NOS T, and HO-1 LL and LM genotypes), with those carrying three or more at-risk alleles having an odds ratio (OR) of 1.56 [95% confidence interval (95% CI), 0.97-2.51] compared with those having none. When examined in relation to iron, carriage of three or more high-risk alleles in the highest tertile of iron intake (OR, 2.27; 95% CI, 0.97-5.29; P trend = 0.02; P interaction = 0.30) or among users of supplemental iron (OR, 2.39; 95% CI, 1.09-5.26; P trend = 0.02; P interaction = 0.11) resulted in a greater than 2-fold increased risk compared with women with no high-risk alleles. Increased risk was also observed among supplement users with the HO-1 LL or LM genotypes (OR, 1.56; 95% CI, 1.01-2.41; P interaction = 0.32) compared with S allele carriers and MM genotypes combined. These results indicate that women with genotypes resulting in potentially higher levels of iron-generated oxidative stress may be at increased risk of breast cancer and that this association may be most relevant among women with high iron intake.
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