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Estrogens and antioxidants indirectly alleviate telomere attrition. However, available clinical data on the association between hormone exposure and telomere length are inconclusive. In the present study, we examined the effects of exogenous estrogen use and of some genetic factors implicated in estrogen metabolism and oxidative stress response on mean leukocyte telomere length. We studied 259 postmenopausal women. Genotyping was conducted for CYP1B1 (rs1056836), COMT (rs4680), GSTP1 (rs1695), MnSOD (rs4880), KRAS (rs61764370), and MTHFR (rs1801133 and rs1801131) polymorphisms. Mean leukocyte telomere length was measured using a quantitative real-time PCR assay. In multivariate analysis we found no association between oral contraceptives or hormone replacement therapy (HRT) and mean leukocyte telomere length. The presence of variant alleles in CYP1B1, KRAS and MTHFR genes was statistically significantly associated with shorter mean leukocyte telomere length. Further, the data provided evidence for the effect modification of the association between HRT and mean leukocyte telomere length by the CYP1B1, KRAS and MTHFR genotypes. Our findings suggest that functionally relevant genetic variants within estrogen and folate metabolic pathways may influence telomere length. We propose these genetic factors should be taken into consideration when interpreting associations between hormone exposure and telomere length.

Hyperandrogenemia has been the most consistent feature of polycystic ovary syndrome (PCOS). Androgens exert their effects through androgen receptors (ARs). The expansion of the codon CAG trinucleotide repeat polymorphism in exon 1 of the AR gene represents a type of genetic alteration associated with changes in the AR gene function. The purpose of this study was to establish a possible association of the AR gene CAG repeat length polymorphism with PCOS, and its influence on clinical and biochemical androgen traits. Two hundred and fourteen Croatian women with PCOS and 209 healthy control women of reproductive age were enrolled. Phenotypic hyperandrogenism, BMI and waist to hip ratio were recorded. Hormonal profiles, fasting insulin and glucose levels were measured on cycle days 3–5. Genotyping of the CAG repeat polymorphism in the AR gene was performed. We found no significant difference in the mean CAG repeat number between the PCOS patients and controls (22.1 ± 3.4 vs. 21.9 ± 3.2, P = 0.286). There was a positive correlation between the CAG repeat length and total testosterone (TT) in the PCOS group (R = 0.225, P = 0.015). A multiple linear regression model using mean CAG repeat length, BMI, age and HOMA-IR as predictors explained 8.5% (adjusted R2) of the variability in serum TT levels. In this model the CAG repeat polymorphism was found to be a significant predictor of serum TT levels in PCOS patients (P = 0.015). The logistic regression analysis revealed that the CAG repeat length is not a significant predictor of hirsutism and acne status (P = 0.921 and P = 0.437, respectively). The model was adjusted for serum TT, free testosterone, androstendione and DHEAS levels as independent variables, which were also not found to be significant predictors of hirsutism (P = 0.687, P = 0.194, P = 0.675 and P = 0.938, respectively) or acne status (P = 0.594, P = 0.095, P = 0.290 and P = 0.151, respectively). In conclusion, the AR CAG repeat polymorphism is not a major determinant of PCOS in the Croatian population, but it is a predictor of serum TT level variability in women with PCOS.

The study aimed to investigate the influence of some generally recognized risk factors for hormone receptor (HR)- and human epidermal growth factor receptor 2 (HER2)-defined breast cancer among Slovenian postmenopausal women.Eligible women diagnosed with breast cancer were compared with 709 controls of the same age and ethnicity. Immunohistochemistry and FISH analyses were used to classify cases into molecular subtypes: 454 HR(+), 106 HR(-), 81 HER2(+) and 603 HER2(-). Adjusted odds ratios and 95% confidence intervals were estimated using multivariate logistic regression analysis.Overweight and obese women were at increased risk of HR(+), HER2(-) and of HR(+), HR(-), HER2(-) tumors, respectively. Women who started menstruating at the age of 11 years or earlier were at decreased risk of ER(-)PR(-) tumors. Users of hormone replacement therapy (HRT) were negatively associated with HR(+) and HER2(-) tumors. The inverse effect was most pronounced with the use of estrogen-only HRT, and longer duration of HRT use did not result in a significant change in risk. In contrast, combined HRT decreased the risk of HER2(+) tumors. Having a first-degree relative with breast and/or ovarian cancer increased the risk of HR(+) and HER2(-) tumors.We conclude that certain breast cancer risk factors may vary by molecular subtypes. According to our results, HRT use may have a greater influence on HR (+) and HER2(-) breast cancers and the risk of HER2-defined breast cancer may differ with respect to the regimen of HRT.

The aim of the study was to analyze the impact of the rs2747648 genetic variant in the estrogen receptor alpha (ER1) gene affecting a putative miR-453-binding site on the risk of breast cancer in postmenopausal women. Furthermore, we examined if the risk changes in a subset of women on hormone replacement therapy (HRT).We studied 530 breast cancer cases and 270 controls of the same age and ethnicity. Duration of HRT use was ascertained through a postal questionnaire. Genotyping was accomplished by TaqMan® allelic discrimination assay. The associations with breast cancer risk were assessed using logistic regression models.The analysis did not reveal any association between the ER1 genetic variant and postmenopausal breast cancer risk, either ER-positive or ER-negative disease. Also, there was no association between the ER1 genetic variant and breast cancer risk in postmenopausal women receiving HRT.There may be an inverse association between the premenopausal women carrying the variant allele and breast cancer, but it was not detected in our analysis for the postmenopausal women, or for those on HRT.

Objective The aim of the study was to examine the influence of the use of hormone replacement therapy (HRT) and of some generally recognized risk factors on breast cancer risk among Slovenian postmenopausal women. Methods Eligible women diagnosed with breast cancer and a control group of women of the same age and ethnicity were invited to participate in the case‐control study via a personal letter and asked to complete a written questionnaire. Adjusted odds ratios and 95% confidence intervals were estimated using multivariate logistic regression analysis. Results A total of 784 cases and 709 controls aged 50‐69 years were enrolled. HRT use was inversely associated with breast cancer risk. The effect was most pronounced with the use of estrogen-only replacement therapy (odds ratio (OR) 0.51, 95% confidence interval (CI) 0.30‐0.87). Longer duration of HRT use did not result in a significant change in risk (1 to55 years of HRT use: OR 0.44, 95% CI 0.26‐0.73;5 years of HRT use: OR 0.51, 95% CI 0.30‐0.87). Obesity (25body mass index530 kg/m 2 : OR 1.34, 95% CI 1.04‐1.73; body mass index30 kg/m 2 : OR 1.89, 95% CI 1.36‐2.63), smoking10 cigarettes per day (OR 1.70, 95% CI 1.20‐2.43), and any first-degree relative with breast or ovarian cancer (OR 1.52, 95% CI 1.11‐2.08) were positively associated with breast cancer risk. Conclusions Our analysis revealed some differences from the previously published literature, which might reflect underlying demographic changes. Comprehensive medical care in HRT users without pre-existing breast abnormalities probably reduces the incidence of new breast cancer cases in Slovenia.

Background A single nucleotide polymorphism located in the 3'-untranslated region of the KRAS oncogene (KRAS variant; rs61764370) disrupts a let-7 miRNA binding and was recently reported to act as a genetic marker for increased risk of developing human cancers. We aimed to investigate an association of the KRAS variant with sporadic and familial breast cancer and breast tumor characteristics. Methods Genotyping was accomplished in 530 sporadic postmenopausal breast cancer cases, 165 familial breast cancer cases (including N = 29, who test positive for BRCA1/2 mutations) and 270 postmenopausal control women using the flurogenic 5' nuclease assay. Information on hormone replacement therapy (HRT) use and tumor characteristics in sporadic breast cancer cases was ascertained from a postal questionnaire and pathology reports, respectively. Associations between the KRAS genotype and breast cancer or breast tumor characteristics were assessed using chi-square test and logistic regression models. Results No evidence of association was observed between the KRAS variant and risk of sporadic and familial breast cancer - either among BRCA carriers or non-BRCA carriers. The KRAS variant was statistically significantly more often associated with human epidermal growth factor receptor 2 (HER2) - positive tumors and tumors of higher histopathologic grade. However, both associations were detected only in HRT users. Conclusion Our data do not support the hypothesis that the KRAS variant rs61764370 is implicated in the aetiology of sporadic or of familial breast cancer. In postmenopausal women using HRT, the KRAS variant might lead to HER2 overexpressed and poorly-differentiated breast tumors, both indicators of a worse prognosis.

Association between long-term hormone replacement therapy (HRT) use and increased risk of breast cancer is still under debate. Functionally relevant genetic variants within the estrogen metabolic pathway may alter exposure to exogenous sex hormones and affect the risk of postmenopausal breast cancer. We investigated the associations of common polymorphisms in 4 genes encoding key proteins of the estrogen metabolic pathway, duration of HRT use and their interactions with breast cancer risk. We studied 530 breast cancer cases and 270 controls of the same age and ethnicity participating in a case-control study of postmenopausal women. Duration of HRT use was ascertained through a postal questionnaire. Genotyping was conducted for CYP1B1 (rs1056836), COMT (rs4680), GSTP1 (rs1695) and MnSOD (rs4880) polymorphisms by PCR-based RFLP and TaqMan® allelic discrimination method. Adjusted odds ratios and 95% confidence intervals were calculated using logistic regression analysis. HRT use was significantly associated with decreased breast cancer risk (p0.001). None of the polymorphisms studied was associated with breast cancer risk. A significant interaction was observed between MnSOD 47TC and HRT use (pinteraction=0.036); the risk of breast cancer associated with long-term vs. short-term HRT use was decreased in women homozygous for the wild-type allele and increased in women with at least one variant allele of the MnSOD 47TC polymorphism. Our results suggest that MnSOD 47TC polymorphism in interaction with long-term HRT use may modify the risk of breast cancer.

Published data on the association between methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms and breast cancer risk are inconclusive. We investigated the independent and the combined effects of two commonly occurring polymorphisms, MTHFR 677C>T (rs1801133) and MTHFR 1298A>C (rs1801131), as well as their interaction with the use of hormone replacement therapy (HRT), to determine their potential contribution to breast cancer risk. We studied 530 breast cancer cases and 270 controls of the same age and ethnicity participating in a case-control study of postmenopausal women. The duration of HRT use was ascertained through a postal questionnaire. Genotyping was conducted by TaqMan® allelic discrimination. Adjusted odds ratios and 95% confidence intervals were calculated using logistic regression. No significant association was observed between either the individual or the combined MTHFR genotypes and the risk of postmenopausal breast cancer. Additionally, no effects resulting from the interaction between MTHFR genotypes and HRT use were detected. Therefore, our data do not support the hypothesis that genetic variation in the MTHFR gene is implicated in the aetiology of postmenopausal breast cancer.

Objective Estrogen plays a key role in breast cancer development and functionally relevant genetic variants within the estrogen metabolic pathway are prime candidates for a possible association with breast cancer risk. We investigated the independent and the combined effects of commonly occurring polymorphisms in four genes encoding key proteins of estrogen metabolic pathway on their potential contribution to breast cancer risk. Methods We studied 530 breast cancer cases and 270 controls of the same age and ethnicity participating in a case-control study of postmenopausal women. Genotyping was conducted for CYP1B1 (rs1056836), COMT (rs4680), GSTP1 (rs1695), and MnSOD (rs4880) polymorphisms by polymerase chain reaction based restriction fragment length polymorphism and TaqMan allelic discrimination method. Adjusted ORs and 95% CIs were calculated using logistic regression. Results None of the 4 genetic variants examined contributed to breast cancer risk individually. When the combined effects of the risk genotypes were investigated, significant associations were observed among women with two high-risk genotypes in CYP1B1 and COMT (OR, 2.0; 95% CI, 1.1 to 3.5) and two high-risk genotypes in COMT and MnSOD (OR, 2.0; 95% CI, 1.0 to 3.8), compared to those with low-risk genotypes. Conclusion Our results suggest that individual susceptibility to breast cancer incidence may be increased by combined effects of the high-risk genotypes in CYP1B1, COMT, and MnSOD estrogen metabolic genes.