Telomere length, cigarette smoking, and bladder cancer risk in men and women.
ABSTRACT Truncated telomeres are among the defining characteristics of most carcinomas. Given the role of telomeres in tumorigenesis, we reasoned that constitutionally short telomeres might be associated with an increased risk of bladder cancer. Using quantitative real-time PCR, we measured relative telomere length in bladder cancer cases and healthy controls and evaluated the association between telomere length, cigarette smoking, and bladder cancer risk in a case-control study nested within the Health Professionals Follow-up Study and a case-control study nested within the Nurses' Health Study. Telomeres were significantly shorter in bladder cancer cases (n = 184) than in controls (n = 192). The mean relative telomere length in cases was 0.23 (SD, 0.16) versus 0.27 (SD, 0.15) in controls (P = 0.001). The adjusted odds ratio for bladder cancer was 1.88 (95% confidence interval, 1.05, 3.36) for individuals in the quartile with the shortest telomeres as compared with individuals in the quartile with the longest telomeres (P(trend) = 0.006). We observed a statistically significant difference in telomere length among men and women (P < 0.001); however, the interaction between gender, telomere length, and bladder cancer risk was not significant. We also observed a significant difference in telomere length across categories of pack-years of smoking (P = 0.01). These findings suggest that truncated telomeres are associated with an increased risk of bladder cancer.
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ABSTRACT: Cadmium and lead are ubiquitous environmental contaminants that might increase risks of cardiovascular disease and other aging-related diseases, but their relationships with leukocyte telomere length (LTL), a marker of cellular aging, are poorly understood. In experimental studies, they have been shown to induce telomere shorten-ing, but no epidemiologic study to date has examined their associations with LTL in the general population. We ex-amined associations of blood lead and cadmium (n = 6,796) and urine cadmium (n = 2,093) levels with LTL among a nationally representative sample of US adults from the National Health and Nutrition Examination Survey (1999– 2002). The study population geometric mean concentrations were 1.67 µg/dL (95% confidence interval (CI): 1.63, 1.70) for blood lead, 0.44 µg/L (95% CI: 0.42, 0.47) for blood cadmium, and 0.28 µg/L (95% CI: 0.27, 0.30) for urine cadmium. After adjustment for potential confounders, the highest (versus lowest) quartiles of blood and urine cad-mium were associated with −5.54% (95% CI: −8.70, −2.37) and −4.50% (95% CI: −8.79, −0.20) shorter LTLs, re-spectively, with evidence of dose-response relationship (P for trend < 0.05). There was no association between blood lead concentration and LTL. These findings provide further evidence of physiological impacts of cadmium at environmental levels and might provide insight into biological pathways underlying cadmium toxicity and chronic disease risks. Cadmium and lead pose a major public health challenge because of their ubiquitous presence in the environment and their established toxicity even at low levels. Although these metals are naturally occurring elements found in the Earth's crust, their widespread occurrence in the environment is largely the result of anthropogenic activity. Lead and cad-mium are global contaminants (1–3) and they accumulate in the body (4, 5), resulting in widespread exposure. The major exposure sources in the general population are diet and tobac-co smoke (1–3). Contaminated dust and air can be important sources of these metals in communities near industrial sites and in certain occupational settings (2, 3). An increasing body of epidemiologic evidence suggests that environmental exposures to lead and cadmium might contribute to the etiology of chronic diseases, such as cardio-vascular disease (6–8) and chronic kidney disease (9–11). Although the mechanisms of these associations are poorly understood, they may be mediated in part through oxidative stress and inflammatory intermediaries. In experimental stud-ies, both metals were found to contribute to oxidative stress (12) and stimulate cytokine production (13, 14). In epidemio-logic studies, cadmium and lead exposure have been positively associated with biological markers of oxidative stress and inflammation, such as γ-glutamyl transferase and C-reactive protein (15–18). Telomeric attrition may also be an important mechanism for metal-induced toxicity. Telomeres are DNA protein structures that function to protect the ends of eukaryotic chromosomes.American journal of epidemiology 12/2014; · 4.98 Impact Factor
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ABSTRACT: We tested the hypothesis that leukocyte telomere length (LTL) is associated with birth weight in both extremes of abnormal fetal growth: small (SGA) and large for gestational age newborns (LGA). Clinical and laboratory variables of the mothers and the neonates were explored; 45 newborns with appropriate weight for gestational age (AGA), 12 SGA and 12 LGA were included. Whether the differences might be explained by variation in OBFC1 (rs9419958) and CTC1 (rs3027234) genes associated with LTL was determined. A significant association between birth weight and LTL was observed; LTL was significantly shorter in LGA newborns (1.01 ± 0.12) compared with SGA (1.73 ± 0.19) p < 0.005, mean ± SE. Maternal (Spearman R = -0.6, p = 0.03) and neonatal LTL (R = -0.25, p = 0.03) were significantly and inversely correlated with maternal history of arterial hypertension in previous gestations. Neonatal LTL was not significantly associated with either rs9419950 or rs3027234, suggesting that the association between neonatal LTL and birth weight is not influenced by genetic variation in genes that modify the interindividual LTL. In conclusion, telomere biology seems to be modulated by abnormal fetal growth; modifications in telomere length might be programmed by an adverse environment in utero.Scientific reports. 01/2015; 5:7869.
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ABSTRACT: Recent evidence from several relatively small nested case-control studies in prospective cohorts shows an association between longer telomere length measured phenotypically in peripheral white blood cell (WBC) DNA and increased lung cancer risk. We sought to further explore this relationship by examining a panel of 7 telomere-length associated genetic variants in a large study of 5,457 never-smoking female Asian lung cancer cases and 4,493 never-smoking female Asian controls using data from a previously reported genome-wide association study. Using a group of 1,536 individuals with phenotypically measured telomere length in WBCs in the prospective Shanghai Women's Health study, we demonstrated the utility of a genetic risk score (GRS) of 7 telomere-length associated variants to predict telomere length in an Asian population. We then found that GRSs used as instrumental variables to predict longer telomere length were associated with increased lung cancer risk (OR = 1.51 (95% CI=1.34-1.69) for upper vs. lower quartile of the weighted GRS, P-value=4.54 × 10(-14) ) even after removing rs2736100 (P-value=4.81 × 10(-3) ), a SNP in the TERT locus robustly associated with lung cancer risk in prior association studies. Stratified analyses suggested the effect of the telomere-associated GRS is strongest among younger individuals. We found no difference in GRS effect between adenocarcinoma and squamous cell subtypes. Our results indicate that a genetic background that favors longer telomere length may increase lung cancer risk, which is consistent with earlier prospective studies relating longer telomere length with increased lung cancer risk. This article is protected by copyright. All rights reserved. © 2014 UICC.International Journal of Cancer 12/2014; · 5.01 Impact Factor