Baseline characteristics including blood and urine metal levels in the Trial to Assess Chelation Therapy 2 (TACT2)

BACKGROUND

The reduction in cardiovascular disease (CVD) events with edetate disodium (EDTA) in the Trial to Assess Chelation Therapy (TACT) suggested that chelation of toxic metals might provide novel opportunities to reduce CVD in patients with diabetes. Lead and cadmium are vasculotoxic metals chelated by EDTA. We present baseline characteristics for participants in TACT2, a randomized, double-masked, placebo-controlled trial designed as a replication of the TACT trial limited to patients with diabetes.

METHODS

TACT2 enrolled 1,000 participants with diabetes and prior myocardial infarction, age 50 years or older between September 2016 and December 2020. Among 959 participants with at least one infusion, 933 had blood and/or urine metals measured at the Centers for Diseases Control and Prevention using the same methodology as in the National Health and Nutrition Examination Survey (NHANES). We compared metal levels in TACT2 to a contemporaneous subset of NHANES participants with CVD, diabetes and other inclusion criteria similar to TACT2's participants.

RESULTS

At baseline, the median (interquartile range, IQR) age was 67 (60, 72) years, 27% were women, 78% reported white race, mean (SD) BMI was 32.7 (6.6) kg/m2, 4% reported type 1 diabetes, 46.8% were treated with insulin, 22.3% with GLP1-receptor agonists or SGLT-2 inhibitors, 90.2% with aspirin, warfarin or P2Y12 inhibitors, and 86.5% with statins. Blood lead was detectable in all participants; median (IQR) was 9.19 (6.30, 13.9) μg/L. Blood and urine cadmium were detectable in 97% and median (IQR) levels were 0.28 (0.18, 0.43) μg/L and 0.30 (0.18, 0.51) μg/g creatinine, respectively. Metal levels were largely similar to those in the contemporaneous NHANES subset.

CONCLUSIONS

TACT2 participants were characterized by high use of medication to treat CVD and diabetes and similar baseline metal levels as in the general US population. TACT2 will determine whether chelation therapy reduces the occurrence of subsequent CVD events in this high-risk population.

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov. Identifier: NCT02733185. https://clinicaltrials.gov/study/NCT02733185.

Maternal cigarette smoking during pregnancy and offspring DNA methylation in midlife

Maternal smoking in pregnancy (MSP) has been associated with DNA methylation in specific CpG sites (CpGs) in infants and children. We investigated whether MSP, independent of own personal active smoking, was associated with midlife DNA methylation in CpGs that were previously identified in studies of MSP-DNA methylation in children. We used data on MSP collected from pregnant mothers of 89 adult women born in 1959-1964 and measured DNA methylation in blood (granulocytes) collected in 2001-2007 (mean age: 43 years). Seventeen CpGs were differentially methylated by MSP, with multiple CpGs mapping to CYP1A1, MYO1G, AHRR, and GFI1. These associations were consistent in direction with prior studies (e.g., MSP associated with more and less methylation in AHRR and CYP1A1, respectively) and, with the exception of AHRR CpGs, were not substantially altered by adjustment for active smoking. These preliminary results confirm prior prospective reports that MSP influences the offspring DNA methylation, and extends the timeframe to midlife, and suggest that these effects may persist into adulthood, independently of active smoking.

Global Level of Plasma DNA Methylation is Associated with Overall Survival in Patients with Hepatocellular Carcinoma

BACKGROUND

The impact of folate deficiency on global DNA methylation is uncertain. It also is unclear whether global DNA methylation is associated with outcome in HCC. LINE-1 methylation levels, as a surrogate marker of global methylation, may be influenced by folate deficiency. However, the interaction between LINE-1 methylation and folate level on overall survival (OS) in hepatocellular carcinoma (HCC) patients is unknown. We evaluated whether LINE-1 hypomethylation and folate deficiency are associated with HCC prognosis.

METHODS

We prospectively recruited 172 HCC patients between 2008 and 2012. LINE-1 methylation levels in plasma and white blood cells (WBC) were measured by pyrosequencing, and plasma folate levels by a radioprotein-binding assay.

RESULTS

Patients with plasma LINE-1 methylation <70.0% (hypomethylation) had significantly worse OS compared with those with ≥70.0% methylation (hypermethylation) [hazard ratio (HR) = 1.77; 95% confidence interval (CI) 1.12-2.79; P = 0.015]. HCC patients with lower plasma folate levels also had worse survival (<27.7 vs. ≥27.7 nmol/L; HR = 1.96; 95% CI, 1.24-3.09; P = 0.004). Furthermore, survival was poor in patients in whom both plasma LINE-1 methylation and folate levels were low compared with those patients in whom both levels were high (HR = 3.36; 95%CI, 1.77-6.40; P < 0.001). This interaction neared statistical significance (P = 0.057). No significant association was found between WBC LINE-1 methylation levels and survival.

CONCLUSIONS

These findings suggest that both lower plasma levels of LINE-1 methylation and folate are associated with worse survival in HCC patients.

Plasma Adiponectin and Hepatocellular Carcinoma Survival Among Patients Without Liver Transplantation

AIM

To investigate the levels of leptin and adiponectin in prediction of hepatocellular carcinoma (HCC) survival among patients without liver transplantation.

MATERIALS AND METHODS

We measured pretreatment plasma leptin and adiponectin in 172 HCC cases who were prospectively followed-up over 7 years.

RESULTS

Gender, hepatitis B virus (HBV) and hepatitis C virus (HCV) infection, high body mass index (BMI), diabetes mellitus (DM) history and Child-Pugh (CP) class were associated with leptin and adiponectin levels, while α-fetoprotein (AFP) and presence of metastasis, being outside the Milan criteria and Barcelona clinic liver cancer (BCLC) stage, were significantly associated with liver transplantation and HCC survival. No significant association was observed for leptin or adiponectin and HCC survival in the overall group. In subgroup analyses among those without liver transplantation, we found significant associations between metastasis, Milan criteria, BCLC stage, hepatitis B surface antigen (HBsAg) and HCC survival. When separately determining the Cox proportional hazard models and Kaplan-Meier survival curves by liver transplantation status, higher adiponectin was significantly associated with an increased hazard ratio (HR) of death of 1.72 (95% confidence interval (CI)=1.12-2.64), i.e. poor survival among patients without liver transplantation. A multivariate Cox proportional hazard model, including adiponectin, CP class, presence of metastasis, tumor outside of Milan criteria, AFP and BCLC stage B/C parameters, also showed significant association with poor HCC survival (likelihood ratio test p<0.0001). No significant impact was observed for leptin on HCC survival regardless of liver transplantation status.

CONCLUSION

Higher levels of plasma adiponectin may predict poor HCC survival among patients without liver transplantation.

Evaluating normalization approaches for the better identification of aberrant microRNAs associated with hepatocellular carcinoma

AIM

Dysregulated microRNAs (miRNAs) have been identified in hepatocellular carcinoma (HCC), but only a small proportion have been confirmed. An appropriate normalizer is crucial to determining the accuracy and reliability of data from miRNA studies.

METHODS

Different normalization strategies were used to validate genome-wide miRNA profiles in HCC tumor and non-tumor tissues, and to determine the consistency and discrepancy of data on dysregulated miRNAs.

RESULTS

Two sets of stable miRNAs (miR-30c/miR-30b and miR-30c/miR-126) were identified in HCC tissues by geNorm and NormFinder tools, respectively. The mean of global miRNAs also showed good stability for ranking the top 1-2 miRNAs, but the stabilities of the manufacturer-recommended ncRNAs controls were poor. Four panels of miRNAs were significantly associated with HCC by separately using various normalizers, and 14 miRNAs were consistently identified by three normalization strategies. Although fewer miRNAs (17-26) were dysregulated in HCC using the global mean or the 2 stable miRNAs as normalizers, perfect clustering of tissues was also obtained with only 1 to 2 misclassifications, suggesting the efficiency of the miRNA panels. Using global mean as the normalizer, the authors identified 7 miRNAs, including 2 novel (miR-324-5p and miR-550) significantly upregulated in HCC that were omitted when using 3 endogenous controls as the normalizer.

CONCLUSION

An optimal normalization strategy to identify biologically important miRNAs in HCC tissue studies of miRNA may be the combination of global mean and 2 stable miRNAs. Selection of appropriate normalization strategies to adjust miRNAs levels is particularly important for epidemiological studies dealing with large data sets and covering multiple experimental batches.

Correlation of DNA methylation levels in blood and saliva DNA in young girls of the LEGACY Girls study

Many epidemiologic studies of environmental exposures and disease susceptibility measure DNA methylation in white blood cells (WBC). Some studies are also starting to use saliva DNA as it is usually more readily available in large epidemiologic studies. However, little is known about the correlation of methylation between WBC and saliva DNA. We examined DNA methylation in three repetitive elements, Sat2, Alu, and LINE-1, and in four CpG sites, including AHRR (cg23576855, cg05575921), cg05951221 at 2q37.1, and cg11924019 at CYP1A1, in 57 girls aged 6-15 years with blood and saliva collected on the same day. We measured all DNA methylation markers by bisulfite-pyrosequencing, except for Sat2 and Alu, which were measured by the MethyLight assay. Methylation levels measured in saliva DNA were lower than those in WBC DNA, with differences ranging from 2.8% for Alu to 14.1% for cg05575921. Methylation levels for the three repetitive elements measured in saliva DNA were all positively correlated with those in WBC DNA. However, there was a wide range in the Spearman correlations, with the smallest correlation found for Alu (0.24) and the strongest correlation found for LINE-1 (0.73). Spearman correlations for cg05575921, cg05951221, and cg11924019 were 0.33, 0.42, and 0.79, respectively. If these findings are replicated in larger studies, they suggest that, for selected methylation markers (e.g., LINE-1), methylation levels may be highly correlated between blood and saliva, while for others methylation markers, the levels may be more tissue specific. Thus, in studies that differ by DNA source, each interrogated site should be separately examined in order to evaluate the correlation in DNA methylation levels across DNA sources.

Genome-wide methylation analyses in glioblastoma multiforme

Few studies had investigated genome-wide methylation in glioblastoma multiforme (GBM). Our goals were to study differential methylation across the genome in gene promoters using an array-based method, as well as repetitive elements using surrogate global methylation markers. The discovery sample set for this study consisted of 54 GBM from Columbia University and Case Western Reserve University, and 24 brain controls from the New York Brain Bank. We assembled a validation dataset using methylation data of 162 TCGA GBM and 140 brain controls from dbGAP. HumanMethylation27 Analysis Bead-Chips (Illumina) were used to interrogate 26,486 informative CpG sites in both the discovery and validation datasets. Global methylation levels were assessed by analysis of L1 retrotransposon (LINE1), 5 methyl-deoxycytidine (5m-dC) and 5 hydroxylmethyl-deoxycytidine (5hm-dC) in the discovery dataset. We validated a total of 1548 CpG sites (1307 genes) that were differentially methylated in GBM compared to controls. There were more than twice as many hypomethylated genes as hypermethylated ones. Both the discovery and validation datasets found 5 tumor methylation classes. Pathway analyses showed that the top ten pathways in hypomethylated genes were all related to functions of innate and acquired immunities. Among hypermethylated pathways, transcriptional regulatory network in embryonic stem cells was the most significant. In the study of global methylation markers, 5m-dC level was the best discriminant among methylation classes, whereas in survival analyses, high level of LINE1 methylation was an independent, favorable prognostic factor in the discovery dataset. Based on a pathway approach, hypermethylation in genes that control stem cell differentiation were significant, poor prognostic factors of overall survival in both the discovery and validation datasets. Approaches that targeted these methylated genes may be a future therapeutic goal.

Exploration of genome-wide circulating microRNA in hepatocellular carcinoma: MiR-483-5p as a potential biomarker

BACKGROUND

MicroRNAs (miRNA) are abundant in the circulation and play a central role in diverse biologic processes; they may be useful for early diagnosis of hepatocellular carcinoma.

METHODS

We conducted a two-phase, case-control study (20 pairs for the discovery set and 49 pairs for the validation set) to test the hypothesis that genome-wide dysregulation of circulating miRNAs differentiates hepatocellular carcinoma cases from controls. Taqman low-density arrays were used to examine genome-wide miRNA expression for the discovery set, and quantitative real-time PCR was used to validate candidate miRNAs for both discovery and validation sets.

RESULTS

Sixty-six miRNAs were found to be significantly overexpressed in plasma of hepatocellular carcinoma cases compared with controls after adjusting for false discovery rate (P < 0.05). A volcano plot indicated that seven miRNAs had greater than 2-fold case-control differences with P < 0.01. Four significant miRNAs (miR-150, miR-30c, miR-483-5p, and miR-520b) detectable in all samples with varied expression levels were further validated in a validation set. MiR-483-5p was statistically significantly overexpressed in hepatocellular carcinoma cases compared with controls (3.20 vs. 0.82, P < 0.0001). Hepatocellular carcinoma risk factors and clinic-pathological characteristics did not influence miR-483-5p expression. The combination of plasma miR-483-5p level and hepatitis C virus status can significantly differentiate hepatocellular carcinoma cases from controls with an area under the curve of 0.908 (P < 0.0001). The sensitivity and specificity were, respectively, 75.5% and 89.8%.

CONCLUSIONS

These preliminary results suggest the importance of dysregulated circulating miR-483-5p as a potential hepatocellular carcinoma biomarker.

IMPACT

Confirmation of aberrant expression of miR-483-5p in a large prospective hepatocellular carcinoma study will provide support for its application to hepatocellular carcinoma detection.

Abstract LB-25: Exploration of genome-wide circulating microRNA in hepatocellular carcinoma (HCC) - dysregulation of miR-483-5p and miR-150 as diagnostic marker

The incidence of hepatocellular carcinoma (HCC) has doubled over the past 20 years in the United States (US). HCC prognosis is poor if not diagnosed and treated at an early stage. MicroRNAs (miRNAs) are a class of small non-coding RNAs that control gene expression by inhibiting translation or inducing cleavage of target messenger RNAs (mRNAs). miRNAs can regulate diverse biological processes including DNA repair, apoptosis, cell proliferation, differentiation and immune function. Circulating miRNAs in cell-free plasma/serum samples have been consistently observed to have high stability and resistance to storage/handling, suggesting their potential use as diagnostic biomarkers. We conducted a two-phase epidemiological case-control study to test the hypothesis that genome-wide dysregulation of circulating miRNAs differentiate HCC cases from controls. A total of 69 HCC patients and 69 controls were recruited and matched on age, gender and ethnicity. Taqman low density arrays were used to examine genome-wide miRNA expression, and quantitative RT-PCR was used to validate promising candidates. Sixty-six miRNAs were found to be significantly over-expressed in plasma of HCC cases compared to controls after adjusting for false discovery rate (p&lt;0.05). A volcano plot indicated that 7 miRNAs had over 2-fold case-control differences with p&lt;0.01. Four significant miRNAs (miR-150, miR-30c, miR-483-5p and miR-520b) detectable in all samples with varied expression levels were further validated in an expanded case-control study. MiR-483-5p was statistically significantly over-expressed in HCC cases compared with controls (3.25 vs. 0.54, p&lt;0.0001). MiR-150 was up-regulated in HCC, but the difference was not significant (5.66 vs. 5.29). The combination of plasma levels of miR-483-5p and miR-150 can significantly differentiate HCC cases from controls with an AUC of 0.850 (p&lt;0.0001). The sensitivity and specificity were, respectively, 63.8% and 85.5%. These preliminary data indicated the importance of dysregulated circulating miRNAs in hepatocarcinogenesis, and suggesting the possibility of using miR-483-5p and miR-150 as diagnostic biomarkers. Large prospective studies are necessary to replicate the current findings, and evaluate the panel of circulating miRNAs in improving early diagnosis of HCC.

Citation Format: Jing Shen, Antai Wang, Qiao Wang, Irina Gurvich, Abby B. Siegel, Helen Remotti, Regina M. Santella. Exploration of genome-wide circulating microRNA in hepatocellular carcinoma (HCC) - dysregulation of miR-483-5p and miR-150 as diagnostic marker. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-25. doi:10.1158/1538-7445.AM2013-LB-25

Dysregulation of circulating microRNAs and prediction of aggressive prostate cancer

BACKGROUND

It is becoming increasingly evident that microRNAs (miRNAs) are associated with the development and progression of prostate cancer (PCa).

METHODS

We examined the hypothesis that plasma miRNA levels can differentiate patients by aggressiveness in 82 PCa patients. Taqman based quantitative RT-PCR assays were performed to measure copy number of target miRNAs.

RESULTS

miR-20a was significantly overexpressed in plasma from patients with stage 3 tumors compared to stage 2 or below (P = 0.03). The expression levels for miR-20a and miR-21 were significantly increased in patients with high risk CAPRA scores (16,623 and 1,595 copies, respectively). Significantly increased miR-21 and miR-145 expression were observed for patients with intermediate or high risk D'Amico scores compared to patients with low risk scores (P = 0.047 and 0.011, respectively). The relapse rates for CAPRA scores ranged from 1.9% for low risk to 9.5% for intermediate risk and to 22.2% for high risk patients (P = 0.023). For D'Amico scores, the relapse rates ranged from 0.0% for low risk to 7.4% for intermediate risk and 17.6% for high risk patients (P = 0.039). Expression of miR-21 and miR-221 significantly differentiated patients with intermediate risk from those with low risk CAPRA scores (AUC = 0.801, P = 0.002). Four miRNAs (miR-20a, miR-21, miR-145, and miR-221) could also distinguish high versus low risk in PCa patients by D'Amico score with an AUC of 0.824.

CONCLUSIONS

These preliminary data suggest that altered plasma miRNAs may be useful predictors to distinguish PCa patients with varied aggressiveness. Further larger studies to validate this promising finding are warranted.

Genetic variation in telomere maintenance genes, telomere length and breast cancer risk

BACKGROUND

Telomeres at the ends of eukaryotic chromosomes play a critical role in maintaining the integrity and stability of the genome and participate in the initiation of DNA damage/repair responses.

METHODS

We performed a case-control study to evaluate the role of three SNPs (TERT-07, TERT-54 and POT1-03) in telomere maintenance genes previously found to be significantly associated with breast cancer risk. We used sister-sets obtained from the New York site of the Breast Cancer Family Registry (BCFR). Among the 313 sister-sets, there were 333 breast cancer cases and 409 unaffected sisters who were evaluated in the current study. We separately applied conditional logistic regression and generalized estimating equations (GEE) models to evaluate associations between the three SNPs and breast cancer risk within sister-sets. We examined the associations between genotype, covariates and telomere length among unaffected sisters using a GEE model.

RESULTS

We found no significant associations between the three SNPs in telomere maintenance genes and breast cancer risk by both conditional logistic regression and GEE models, nor were these SNPs significantly related to telomere length. Among unaffected sisters, shortened telomeres were statistically significantly correlated with never hormone replacement therapy (HRT) use. Increased duration of HRT use was significantly associated with reduced telomere length. The means of telomere length were 0.77 (SD = 0.35) for never HRT use, 0.67 (SD = 0.29) for HRT use < 5 yrs and 0.59 (SD = 0.24) for HRT use ≥ 5 yrs after adjusting for age of blood donation and race and ethnicity.

CONCLUSIONS

We found that exogenous hormonal exposure was inversely associated with telomere length. No significant associations between genetic variants and telomere length or breast cancer risk were observed. These findings provide initial evidence to understand hormonal exposure in the regulation of telomere length and breast cancer risk but need replication in prospective studies.

XRCC1 polymorphisms and breast cancer risk from the New York Site of the Breast Cancer Family Registry: A family-based case-control study

Background:

XRCC1 is a scaffold protein involved in the early and late stages of Base Excision Repair (BER). Three DNA polymorphisms occur in XRCC1, resulting in non-synonymous amino acid changes, which could alter the binding or regulatory activities of XRCC1.

Materials and Methods:

We used a family-based case-control study design to evaluate the association between XRCC1 polymorphisms and breast cancer risk. Participants were breast cancer cases and their unaffected sisters enrolled in the New York Site of the Breast Cancer Family Registry. Conditional logistic regression was used to assess associations between genotype and breast cancer. XRCC1 mRNA levels and DNA nicking activity were measured in lymphoblastoid cell lines from unaffected sisters to determine whether the XRCC1 R399Q polymorphism has a functional effect on expression or protein activity.

Results:

XRCC1 194W was associated with a non-significant increase in breast cancer, while XRCC1 280H and XRCC1 399Q were associated with a non-significant decrease in breast cancer. We found a significant increase in XRCC1 expression in 399Q/Q lymphoblastoid cell lines from unaffected sisters (n=28, P=0.03). An increase in median nicking activity was not statistically significant.

Conclusions:

Our results suggest that XRCC1 399Q may alter mRNA expression and DNA repair phenotype, although the main effects of the genotype were not significantly associated with familial cancer risk. Additional research on the regulation of XRCC1 expression will contribute to an understanding of how this polymorphism may impact disease risk.

Plasma protein carbonyls and breast cancer risk in sisters discordant for breast cancer from the New York site of the Breast Cancer Family Registry

Reactive oxygen species are important in the pathogenesis of many diseases, including breast cancer. Several population-based case-control studies have shown that various biomarkers of oxidative stress are associated with an increase in breast cancer risk. We selected sisters discordant for breast cancer (n=645) from the New York site of the Breast Cancer Family Registry to explore factors that contribute to variation in plasma protein carbonyls, and to determine whether this biomarker is associated with an increase in breast cancer risk among those with a family history. Late age at menarche, hormone replacement therapy use, and Hispanic race were significantly associated with lower plasma protein carbonyl levels in unaffected sisters. Plasma protein carbonyls were associated with an increase in breast cancer risk [Q2 odds ratio (OR), 1.4; 95% confidence interval (CI), 0.8-2.7; Q3 OR, 2.4; 95% CI, 1.1-4.9; Q4 OR, 1.9; 95% CI, 0.8-4.2], although not in a dose-dependent manner. These data suggest that oxidative damage is a risk factor for breast cancer in high-risk women.

Double-strand breaks repair in lymphoblastoid cell lines from sisters discordant for breast cancer from the New York site of the BCFR

Unrepaired DNA double-strand breaks (DSBs) may have serious consequences for cells by inducing chromosomal aberrations, thereby increasing genetic instability and cancer risk. One's capacity to repair DSB is therefore an important factor to consider when estimating cancer risk. We assessed DNA end-joining (EJ) capacity in cell lines derived from sisters discordant for breast cancer to determine if individual differences in DSB repair are a significant risk factor. We used an in vitro phenotypic assay on nuclear extracts from lymphoblasts of 179 subjects including 86 cases and 93 controls. EJ activity was functionally estimated as the ability of extracts to join together monomers of the plasmid pUC18 linearized either with sticky (EcoRI) or blunt ends (HincII). Mean percentage of EJ capacity was slightly lower in cases than controls, both for EcoRI (cases 27.9 +/- 11.1; controls 29.6 +/- 10.7, P = 0.28) and HincII substrates (cases 28.8 +/- 12.2; controls 30.6 +/- 13.0, P = 0.36); however, no significant differences were observed. Categorizing EJ capacity into tertiles and using the highest activity as the referent, we observed elevated associations for each tertile of decreased repair [Odds ratio (OR) = 2.20, 95% confidence interval (CI) = 0.77-6.22 and OR = 4.22, 95% CI thinsp;= 1.22-14.0, P = 0.02], respectively, for EcoRI. Results were not statistically significant for HincII (OR = 1.37, 95% CI = 0.51-3.70 and OR = 2.32, 95% CI = 0.57-9.38, P = 0.24). These data suggest that individual differences in EJ capacity may represent a risk factor predisposing women to breast cancer.

Estrogen-biosynthesis gene CYP17 and its interactions with reproductive, hormonal and lifestyle factors in breast cancer risk: results from the Long Island Breast Cancer Study Project

The genes that are involved in estrogen biosynthesis, cellular binding and metabolism may contribute to breast cancer susceptibility. We examined the effect of the CYP17 promoter T --> C polymorphism and its interactions with the reproductive history, exogenous hormone use and selected lifestyle risk factors on breast cancer risk among 1037 population-based incident cases and 1096 population-based controls in the Long Island Breast Cancer Study Project. Overall, there were no associations between the CYP17 genotype and breast cancer risk. Among postmenopausal women, the joint exposure to higher body mass index (BMI) and the variant C allele was associated with an increased risk of breast cancer [odds ratio (OR), 1.60; 95% confidence interval (CI), 1.15-2.22]. The joint exposure to the variant C allele and long-term use of hormone replacement therapy (HRT) (>51 months) was related to an increased risk of breast cancer (OR, 1.51; 95% CI, 0.99-2.31) especially estrogen receptor-positive, progesterone receptor-positive breast cancer (OR, 1.87; 95% CI, 1.08-3.25). Among the control population, the CYP17 variant C allele was inversely associated with long-term use of postmenopausal HRT and a higher BMI in postmenopausal women. In conclusion, the findings suggest that the CYP17 variant C allele may increase breast cancer risk in conjunction with long-term HRT use and high BMI in postmenopausal women.

A CYP19 (aromatase) polymorphism is associated with increased premenopausal breast cancer risk

Due to the established association between estrogen levels and breast cancer risk, polymorphic variation in genes regulating estrogen levels is thought to be related to breast cancer risk. Aromatase, the protein product of the CYP19 gene, is involved in the production of endogenous estrogens via androgen conversion. We examined whether polymorphic variation in CYP19 associated with increased breast cancer risk in a population based case-control study. We examined two single nucleotide polymorphisms (SNP), rs1008805 (A/G) and rs730154 (C/T), which have been shown to tag SNPs within two different haplotype blocks in CYP19. Among premenopausal women, the presence of at least one G allele at rs1008805 was significantly associated with an increase in the risk of breast cancer (OR = 1.72 [95% CI, 1.20-2.49]), especially with estrogen and progesterone receptor negative breast cancer (OR = 3.89 [1.74-8.70] and OR = 2.52 [1.26-5.05], respectively). No association was observed among postmenopausal women (OR = 1.06 [0.82-1.36]). There was no significant association between rs730154 and breast cancer, regardless of menopausal status. Our results suggest that premenopausal women carrying the G allele at CYP19 rs1008805 have increased risk of breast cancer. The finding supports the potential role of variation in estrogen biosynthesis genes in premenopausal breast cancer risk.

Short telomere length and breast cancer risk: a study in sister sets

Telomeres consist of a tandem repeats of the sequence TTAGGG at the ends of chromosomes and play a key role in the maintenance of chromosomal stability. Previous studies indicated that short telomeres are associated with increased risk for human bladder, head and neck, lung, and renal cell cancer. We investigated the association between white blood cell telomere length and breast cancer risk among 268 family sets (287 breast cancer cases and 350 sister controls). Telomere length was assessed by quantitative PCR. The mean telomere length was shorter in cases (mean, 0.70; range, 0.03-1.95) than in unaffected control sisters (mean, 0.74; range, 0.03-2.29), but no significant difference was observed (P = 0.11). When subjects were categorized according to the median telomere length in controls (0.70), affected sisters had shorter telomeres compared with unaffected sisters after adjusting for age at blood donation and smoking status [odds ratio (OR), 1.3; 95% confidence interval (95% CI), 0.9-1.8], but the association was not statistically significant. The association by quartile of telomere length (Q4 shortest versus Q1 longest) also supported an increase in risk from shorter telomere length, although the association was not statistically significant (OR, 1.6; 95% CI, 0.9-2.7). This association was more pronounced among premenopausal women (OR, 2.1; 95% CI, 0.8-5.5) than postmenopausal women (OR, 1.3; 95% CI, 0.5-3.6 for Q4 versus Q1). If these associations are replicated in larger studies, they provide modest epidemiologic evidence that shortened telomere length may be associated with breast cancer risk.

Variants in estrogen metabolism and biosynthesis genes and urinary estrogen metabolites in women with a family history of breast cancer

We examined associations between polymorphisms in genes related to estrogen metabolism (CYP1B1 codon 432G --> C rs#1056836, CYP1B1 codon 453A --> G rs#1800440, COMT codon 158G --> A rs#4680) and biosynthesis (CYP17 T --> C promoter rs#743572, CYP19 exon 4 TTTA repeat) and urinary estrogen metabolites (2-hydroxyestrogens (2-OHE), 16alpha-hydroxyestrone (16alpha-OHE1), and their ratio) in a pilot study of 64 pre- and post-menopausal women with a family history of breast cancer. Women were participants in the Metropolitan New York Registry of Breast Cancer Families, one of six international sites of the National Cancer Institute's Breast Cancer Family Registry. We used linear regression to examine the effects of genetic variants on log-transformed urinary estrogen metabolites. After adjusting for menopausal status, BMI, and age, carriers of the CYP1B1 codon 453G variant allele had 31.0% lower levels of 2-OHE (P-value = 0.05) and 40.2% lower levels of 16alpha-OHE1 (P = 0.01). Results were similar after restricting the analyses to pre-menopausal women (n = 41). Consistent with other studies, among pre-menopausal women, carriers of the COMT codon 158A variant allele had increased 2-OHE levels (P = 0.03) and an increased 2-OHE/16alpha-OHE1 ratio (P = 0.04); carriers of the CYP17 C promoter variant allele had increased 2-OHE levels (P = 0.08). To our knowledge this is the first report showing associations between the CYP1B1 codon 453G variant allele and urinary 2-OHE and 16alpha-OHE1 metabolites. Further larger studies should be conducted to confirm these results. Future identification of individuals with genetic polymorphisms that affect estrogen metabolism and biosynthesis may help characterize women at higher breast cancer risk and could guide breast cancer prevention strategies for those individuals.

Variants in estrogen-biosynthesis genes CYP17 and CYP19 and breast cancer risk: a family-based genetic association study

BACKGROUND

Case-control studies have reported inconsistent results concerning breast cancer risk and polymorphisms in genes that control endogenous estrogen biosynthesis. We report findings from the first family-based association study examining associations between female breast cancer risk and polymorphisms in two key estrogen-biosynthesis genes CYP17 (T-->C promoter polymorphism) and CYP19 (TTTA repeat polymorphism).

METHODS

We conducted the study among 278 nuclear families containing one or more daughters with breast cancer, with a total of 1123 family members (702 with available constitutional DNA and questionnaire data and 421 without them). These nuclear families were selected from breast cancer families participating in the Metropolitan New York Registry, one of the six centers of the National Cancer Institute's Breast Cancer Family Registry. We used likelihood-based statistical methods to examine allelic associations.

RESULTS

We found the CYP19 allele with 11 TTTA repeats to be associated with breast cancer risk in these families. We also found that maternal (but not paternal) carrier status of CYP19 alleles with 11 repeats tended to be associated with breast cancer risk in daughters (independently of the daughters' own genotype), suggesting a possible in utero effect of CYP19. We found no association of a woman's breast cancer risk either with her own or with her mother's CYP17 genotype.

CONCLUSION

This family-based study indicates that a woman's personal and maternal carrier status of CYP19 11 TTTA repeat allele might be related to increased breast cancer risk. However, because this is the first study to report an association between CYP19 11 TTTA repeat allele and breast cancer, and because multiple comparisons have been made, the associations should be interpreted with caution and need confirmation in future family-based studies.

A family-based genetic association study of variants in estrogen-metabolism genes COMT and CYP1B1 and breast cancer risk

In this paper, we report findings from a family-based association study examining the association between polymorphisms in two key estrogen-metabolism genes CYP1B1 (codon 432 G --> C and codon 453 A --> G variants) and COMT (codon 158 G --> A variant) and female breast cancer. We conducted the study among 280 nuclear families containing one or more daughters with breast cancer with a total of 1124 family members (702 with available constitutional DNA and questionnaire data and 421 without). These nuclear families were selected from breast cancer families participating in the Metropolitan New York Registry (MNYR) - one of the six centers of NCI's Breast Cooperative Family Registry. We used likelihood-based statistical methods to examine the allelic associations. We found none of the variant alleles of the CYP1B1 and COMT genes to be associated with breast cancer in these families. This was consistent with results from matched case-control analyses using all available sib-ships in these families. However, we found that parental carrier status of the CYP1B1 codon 453 variant G allele and the COMT codon 158 variant A allele was associated with breast cancer risk in daughters (independent of the daughters' own genotype). In conclusion, findings from this family-based study indicate that a woman's own CYP1B1 or COMT genotypes are not associated with her breast cancer risk. Although the study found that parental carrier status of certain CYP1B1 or COMT genotypes might be associated with daughter's breast cancer risk, the biological basis as well as independent confirmation of this finding need to be investigated in future larger family-based studies before making meaningful inferences.