Background and aims: Aberrations in telomere length can have important implications in cancer. Using a cohort of 1007 patients, we investigated whether leukocyte telomere length (LTL) in patients with colorectal cancer (CRC) is associated with survival. We also investigated whether some telomere maintenance genes are associated with survival in these patients. Methods: The Biobank for Gastrointestinal Health Research (BGHR), an ongoing project involving collection of biospecimens at the Mayo Clinic, was utilized to obtain data from patients diagnosed with stage II or III CRC. Blood samples were collected prior to chemotherapy/radiation and DNA was extracted for measuring median LTL. The main outcome measures were overall survival (OS) and disease-free survival (DFS) by disease stage. Results: A significant inverse relationship was observed with patient age and LTL (spearman correlation coefficient (r) = -0.48, 95%; p = 1.13 × 10-58). Females had significantly longer LTL than males (p = 3.97 × 10-5). The rs1317082 SNP in the TERC gene was significantly associated with both OS and DFS in combined stage II and stage III patients (p = 0.017 and p = 0.023, respectively). A statistically significant association of the OBFC1 SNP (rs9419958) was observed for OS for the combined stage II and stage III patients (p = 0.016). Importantly, LTL was significantly associated with both OS and DFS (p = 0.008 and 0.044 respectively) in combined stage II and stage III patients. Conclusions: Our results show that LTL is predictive of OS and DFS for stage II and III CRC patients, particularly over a longer follow-up, extending beyond five years after a diagnosis of CRC, and certain SNPs in genes involved in telomere maintenance are significantly associated with patient outcomes, independent of telomere length.

Abstract Introduction Lung cancer is the leading cause of cancer-related mortality worldwide, with approximately 25% of cases occurring in never-smokers, particularly East Asian women. Mitochondria are critical regulators of cellular energy production and oxidative stress responses, and mitochondrial DNA (mtDNA) is especially susceptible to damage from environmental exposures. While findings from previous studies on mtDNA copy number (mtDNAcn) and lung cancer risk have been mixed, mtDNA fraction with breaks (mtDNAfb) has recently emerged as a potential marker of oxidative stress and mitochondrial integrity. We investigated associations between prediagnostic mtDNAfb, mtDNAcn, and lung cancer risk in never-smoking women in the prospective Shanghai Women’s Health Study (SWHS). Methods This nested case-control study included 789 incident lung cancer cases and 789 controls individually matched on birth year and blood collection date from the SWHS, a prospective cohort of 74,942 women enrolled between 1996 and 2000. DNA was extracted from white blood cells or buccal cells, and mtDNAfb was quantified using a high-throughput qPCR assay comparing amplification signals from TaqI-treated (digested) and untreated samples. Relative mtDNAcn was derived from qPCR measurements normalized to a reference gene. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the associations of mtDNAfb and mtDNAcn with lung cancer risk, adjusting for age, body mass index, and assay plate. Sensitivity analyses further controlled for education, environmental tobacco smoke exposure, family history of lung cancer, and mutual adjustment for mtDNAfb and mtDNAcn. Interaction between mtDNAfb and mtDNAcn was tested on a multiplicative scale. Results We observed higher mtDNAfb was associated with lower risk of lung cancer with participants in the highest mtDNAfb tertile having 34% lower odds compared with those in the lowest tertile (p trend = 0.026). No independent association was observed for mtDNAcn; however, a multiplicative interaction between mtDNAfb and mtDNAcn was identified (p interaction = 8.3 × 10-6) where the association between mtDNAfb and lung cancer was more pronounced among participants with low mtDNAcn (OR = 0.47, 95% CI: 0.29-0.78) than those with high mtDNAcn (OR = 1.02, 95% CI: 0.58-1.79). Conclusions Lower mtDNAfb was associated with increased lung cancer risk among never-smoking women, particularly among women with low mtDNAcn, suggesting possible pathologic reductions in mitochondrial biogenesis and functioning, and consequently, reduced innate immune activation. These findings provide novel insights into mitochondrial dysfunction as a potential mechanism underlying lung cancer in never-smokers and warrant replication and mechanistic investigation in future studies. Citation Format: Batel Blechter, Xiao-Ou Shu, Wei Hu, Elizabeth Francies, Wei Zheng, Yu-Tang Gao, Qiuyin Cai, Hui Cai, Gong Yang, H. Dean Hosgood, Richard Cawthon, Qing Lan. Mitochondrial DNA breaks and copy number and the risk of lung cancer in never-smoking women [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 3592.

Background: The complex relationship between measured leukocyte telomere length (LTL), genetically predicted LTL (gTL), and carcinogenesis is exemplified by lung cancer. We previously reported associations between longer pre-diagnostic LTL, gTL, and increased lung cancer risk among European and East Asian populations. However, we had limited statistical power to examine the associations among never smokers by gender and histology.Methods: To investigate further, we conducted nested case-control analyses on an expanded sample of never smokers from the prospective Shanghai Women's Health Studies (798 cases and 792 controls) and Shanghai Men's Health Studies (161 cases and 162 controls). We broke the case-control matching and used multivariable unconditional logistic regression models to estimate the ORs and 95% confidence intervals (CI) of incident lung cancer and adenocarcinoma (LUAD), in relation to LTL measured using quantitative PCR and gTL determined using a polygenic score. In addition, we conducted Mendelian randomization (MR) using MR-PRESSO.Results: We found striking dose-response relationships between longer LTL and gTL, and increased lung cancer risk among never-smoking women (P trendLTL = 4x10-6; P trendgTL = 3x10-4). Similarly, among never-smoking men, longer measured LTL was associated with over triple the risk compared with those with the shortest (OR, 3.48; 95% CI, 1.85-6.57). The overall results were similar for LUAD among women and men. MR analyses supported causal associations with LUAD among women (OR1 SD gTL, 1.19; 95% CI, 1.03-1.37; P = 0.03).Conclusions: Longer pre-diagnostic LTL is associated with increased lung cancer risk among never smokers.Impact: Our findings firmly support the role of longer telomeres in lung carcinogenesis.

BACKGROUND:Household air pollution (HAP) from indoor combustion of solid fuel is a global health burden linked to lung cancer. In Xuanwei, China, lung cancer rate for nonsmoking women is among the highest in the world and largely attributed to high levels of polycyclic aromatic hydrocarbons (PAHs) that are produced from combustion of smoky (bituminous) coal used for cooking and heating. Epigenetic age acceleration (EAA), a DNA methylation-based biomarker of aging, has been shown to be highly correlated with biological processes underlying the susceptibility of age-related diseases. We aim to assess the association between HAP exposure and EAA. METHODS:We analyzed data from 106 never-smoking women from Xuanwei, China. Information on fuel type was collected using a questionnaire, and validated exposure models were used to predict levels of 43 HAP constituents. Exposure clusters were identified using hierarchical clustering. EAA was derived for five epigenetic clocks defined as the residuals resulting from regressing each clock on chronological age. We used generalized estimating equations to test associations between exposure clusters derived from predicted levels of HAP exposure, ambient 5-methylchrysene (5-MC), a PAH previously found to be associated with risk of lung cancer, and EAA, while accounting for repeated-measurements and confounders. RESULTS:We observed an increase in GrimAge EAA for clusters with 31 and 33 PAHs reflecting current (β = 0.77 y per standard deviation (SD) increase, 95 % CI:0.36,1.19) and childhood (β = 0.92 y per SD, 95 % CI:0.40,1.45) exposure, respectively. 5-MC (ng/m3-year) was found to be associated with GrimAge EAA for current (β = 0.15 y, 95 % CI:0.05,0.25) and childhood (β = 0.30 y, 95 % CI:0.13,0.47) exposure. CONCLUSIONS:Our findings suggest that exposure to PAHs from indoor smoky coal combustion, particularly 5-MC, is associated with GrimAge EAA, a biomarker of mortality.

Simple Summary Colorectal cancer risk and survival have previously been associated with telomere length in peripheral blood leukocytes and tumor tissues. We quantitatively assessed these associations through a systematic review and meta-analysis. Following PRISMA guidelines, we identified relevant studies through database searches, and performed meta-analyses using random effects models. We found no association between telomere length in circulating leukocytes and the risk of developing colorectal cancer, however, shorter leukocyte telomeres were associated with a worse survival in patients with colorectal cancer. Therefore, telomere length may serve as a potential biomarker especially for colorectal cancer prognosis. Larger prospective cohort studies are needed to further confirm this potential association. (1) Background: Colorectal cancer risk and survival have previously been associated with telomere length in peripheral blood leukocytes and tumor tissue. A systematic review and meta-analysis of the literature was conducted. The PubMed, Embase, and Web of Science databases were searched through March 2022. (2) Methods: Relevant studies were identified through database searching following PRISMA guidelines. Risk estimates were extracted from identified studies; meta-analyses were conducted using random effects models. (3) Results: Fourteen studies were identified (eight on risk; six on survival) through systematic review. While no association was observed between circulating leukocyte telomere length and the risk of colorectal cancer [overall OR (95% CI) = 1.01 (0.82-1.24)], a worse survival for those with shorter telomeres in leukocytes and longer telomeres in tumor tissues was observed [Quartile(1)/Quartile(2-4) overall HR (95% CI) = 1.41 (0.26-7.59) and 0.82 (0.69-0.98), respectively]. (4) Conclusions: Although there was no association with colorectal cancer risk, a poorer survival was observed among those with shorter leukocyte telomere length. Future larger studies evaluating a potentially non-linear relationship between telomeres and colorectal cancer are needed.

Household air pollution (HAP) from indoor combustion of solid fuel is a global health burden that has been linked to multiple diseases including lung cancer. In Xuanwei, China, lung cancer rate for non-smoking women is among the highest in the world and largely attributed to high levels of polycyclic aromatic hydrocarbons (PAHs) that are produced from combustion of smoky (bituminous) coal. Alu retroelements, repetitive mobile DNA sequences that can somatically multiply and promote genomic instability have been associated with risk of lung cancer and diesel engine exhaust exposure. We conducted analyses for 160 non-smoking women in an exposure assessment study in Xuanwei, China with a repeat sample from 49 subjects. Quantitative PCR was used to measure Alu repeat copy number relative to albumin gene copy number (Alu/ALB ratio). Associations between clusters derived from predicted levels of 43 HAP constituents, 5-methylchrysene (5-MC), a PAH previously associated with lung cancer in Xuanwei and was selected a priori for analysis, and Alu repeats were analyzed using generalized estimating equations. A cluster of 31 PAHs reflecting current exposure was associated with increased Alu copy number (β:0.03 per standard deviation change; 95% confidence interval (CI):0.01,0.04; P-value = 2E-04). One compound within this cluster, 5-MC, was also associated with increased Alu copy number (P-value = 0.02). Our findings suggest that exposure to PAHs due to indoor smoky coal combustion may contribute to genomic instability. Additionally, our study provides further support for 5-MC as a prominent carcinogenic component of smoky coal emissions. Further studies are needed to replicate our findings.

Importance Research suggests that increased mitochondrial DNA copy number (mtDNAcn) is associated with increased risk of non-Hodgkin lymphoma (NHL); however, no studies to date have evaluated whether the mitochondrial DNA fraction with breaks (mtDNAfb) is associated with risk of NHL. Objective To evaluate the association of mtDNAfb with NHL risk. Design, Setting, and Participants This nested case-control study, which used prospectively collected samples as part of baseline enrollment (from 1985 through 1988) of 29 133 men who smoked for the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study conducted in southwest Finland, included 107 incident NHL cases and 107 controls (matched on date of birth ±5 years). Analyses were conducted from January to September 2022. Exposure High-throughput real-time polymerase chain reaction assays quantifying mtDNAfb. Main Outcomes and Measures Incident NHL cases were identified in the ATBC Study through April 30, 2002, using the Finnish Cancer Registry and the Register of Causes of Death. The mtDNAfb was quantified and categorized based on the median, tertile, and quartile distributions among controls. Odds ratios (ORs) and 95% CIs were estimated using conditional logistic regression models to assess the associations between categorized mtDNAfb and future risk of NHL, controlling for age, body mass index, number of cigarettes smoked per day, number of pack-years, and mtDNAcn. Results A total of 29 133 men (median [IQR] age, 57.2 [52.6-62.5] years) participated in ATBC Study. Higher mtDNAfb was associated with an increased risk of NHL (median OR, 2.89; 95% CI, 1.40-5.93) in a dose-dependent manner (quartile 2 vs 1 OR, 1.24; 95% CI, 0.43-3.40; quartile 3 vs 1 OR, 3.58; 95% CI, 1.39-9.24; quartile 4 vs 1 OR, 3.42; 95% CI, 1.30- 8.99; P = .004 for trend). Conclusions and Relevance This study’s findings suggest that increased mtDNAfb is associated with an increased future risk of NHL. Additional studies are needed to confirm these findings, particularly among women and nonsmokers.

Determinants of leukocyte telomere length among controls

Household air pollution (HAP) from indoor combustion of solid fuel is a global health burden that has been linked to lung cancer. A striking example occurs in Xuanwei, China where the lung cancer rate for never smoking women is among the highest in the world and largely attributed to high levels of various toxic constituents, including polycyclic aromatic hydrocarbons (PAHs), a combustion product of smoky (bituminous) coal used for cooking and heating. Several air pollution constituents have been associated with epigenetic accelerated aging (EAA) derived from DNA methylation (DNAm)-based biomarkers that are highly correlated with biological processes underlying aging-related diseases. We aim to assess the association between HAP exposure and EAA in Xuanwei, China. We analyzed 106 never smoking women in an exposure assessment study in Xuanwei, China with a repeat DNA sample from 23 subjects. Household fuel type used for cooking and heating (smoky vs. smokeless coal) was collected using a questionnaire, and exposure models were used to predict levels of 43 individual HAP constituents for current and childhood exposure. Leukocyte DNAm was measured using Illumina EPIC array. EAA was derived for five clocks using the Horvath calculator and defined as the residuals resulting from regressing each clock on chronological age. We used generalized estimating equations to assess the associations between fuel type, clusters derived from predicted levels of HAP exposure, and ambient 5-methylchrysene (5-MC), a carcinogenic PAH previously associated with lung cancer in Xuanwei and selected a priori for analyses, as independent variables and EAA clocks as dependent variables, while accounting for repeated-measurements. We observed a significant increase in GrimAge EAA among smoky coal users compared to smokeless coal users for current (β=1.84 years (y), 95% confidence interval (CI): 0.59, 3.09, P-value=0.004) and childhood (β=4.14 y, 95% CI: 1.63, 6.64, P-value=0.001) exposures. We also observed a monotonic increase in GrimAge EAA for a cluster of 31 PAHs reflecting current exposure (β=0.77 y, 95% CI: 0.36, 1.19, P-value=3 × 10−4) and for a cluster of 33 PAHs reflecting childhood exposure (β=0.92 y, 95% CI: 0.40, 1.45, P-value=0.001). Ambient 5-MC, one of the constituents within the PAH clusters, was found to have an increasing monotonic relationship with GrimAge EAA for current (β=0.15 y, 95% CI: 0.05, 0.25, P-value=0.003) and childhood (β=0.30 y, 95% CI: 0.13, 0.47, P-value=4.7 × 10−4) exposures. Our findings suggest that exposure to PAH from indoor smoky coal combustion is associated with EAA, particularly for the GrimAge clock, a strong biomarker of mortality. This finding is consistent with our recent observation linking accelerated GrimAge to increased risk of lung cancer in a prospective study of never smoking women in China. Additionally, our study provides further support for 5-MC as a prominent carcinogenic component of smoky coal emissions. Citation Format: Batel Blechter, Andres Cardenas, Seraphina (Junming) Shi, Mohammad L. Rahman, Jason Y.Y. Wong, Wei Hu, George S. Downward, Lutzen Portengen, Richard Cawthon, H. Dean Hosgood, Jihua Li, Debra T. Silverman, Yunchao Huang, Roel Vermeulen, Nathaniel Rothman, Qing Lan. Smoky coal exposure is associated with epigenetic accelerated aging. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4219.

CCR Translation for the Article from A Prospective Study of Telomere Length Measured by Monochrome Multiplex Quantitative PCR and Risk of Non-Hodgkin Lymphoma

INTRODUCTION:Telomere shortening, as seen with aging, can cause chromosomal instability and promote cancer progression. We investigated the association between circulating telomere length and overall and disease-free survival in a sub-cohort of patients with colorectal cancer. METHODS:Baseline genomic DNA from blood leukocytes was extracted from N = 92 newly diagnosed stage I-IV patients with colorectal cancer enrolled at the ColoCare Study site in Heidelberg, Germany. Detailed information on clinicodemographic (including age) and lifestyle risk factors, and clinical outcomes (including recurrence and survival) was collected. Telomere length was measured in DNA using multiplex quantitative polymerase chain reaction. Kaplan Meier survival curves were generated comparing shorter to longer telomere lengths with log-rank testing. RESULTS:The mean T/S ratio for study patients was 0.5 (range: 0.3-0.9). Shorter telomeres were associated with older age at baseline. Patients with shorter telomeres experienced a worse overall and disease-free survival, although this association did not reach statistical significance. Kaplan-Meier survival curves for those with circulating telomere length below vs. above the median showed poorer overall (log-rank p = 0.31) and disease-free survival (long-rank p = 0.23). CONCLUSIONS:Our results suggest that individuals with shorter telomeres, as seen with aging, may experience a worse overall and disease-free survival after colorectal cancer diagnosis. Larger sample sizes with longer follow-up are needed to further evaluate telomere length as a prognostic biomarker in colorectal cancer progression.

Prospective cohort and genome-wide association studies have found consistent associations between longer leukocyte telomere length (LTL) and increased lung cancer risk. These findings present a paradox in the traditional expectations of telomere dynamics in cancer development, as longer telomeres are generally considered to be reflective of less advanced age and greater genomic stability. We posited that longer LTL may reflect or lead to delayed cellular senescence allowing cells to accumulate genomic abnormalities that drive lung carcinogenesis. Furthermore, increased copy number of Alu retroelements, repetitive mobile DNA sequences that are approximately 300 base pairs in length, could also reflect genomic instability. We previously found that exposure to diesel exhaust, a known lung carcinogen, was associated with increased Alu copy number and suspect that increased Alu retrotransposition could influence lung carcinogenesis. However, the interrelationship between Alu retroelements, LTL, and lung cancer is unknown. Therefore, we investigated associations between Alu copy number, LTL, and lung cancer risk in the prospective Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. We conducted a nested case-control study of 410 confirmed incident lung cancer cases and 416 controls individually matched on age, sex, race/ethnicity, study center, and blood draw date. Quantitative PCR was used to measure Alu copy number and telomere length relative to albumin (Alb) copy number (Alu/Alb and T/S ratio, respectively) in pre-diagnostic leukocytes. Conditional logistic regression was used to estimate associations between quartiles (Q) of Alu/Alb ratio (reference=Q1) and lung cancer risk, adjusted for matching factors, smoking status and packyears, and LTL. Additionally, we dichotomized Alu/Alb ratio and LTL at their medians and created a cross-combination variable to assess combined effects. We found a positive dose-response relationship between Alu/Alb ratio and lung cancer risk (odds ratio (OR), 95% confidence intervals (CI): Q2: 1.34 (0.73, 2.48); Q3:1.89 (0.94, 3.84); Q4: 2.66 (1.03, 5.63); p-trendordinal=0.02). The association was apparent for lung adenocarcinoma (LUAD) (Q2: 1.32 (0.46, 3.77); Q3: 2.88 (0.90, 9.25); Q4: 5.07 (1.29, 19.87); p-trendordinal=0.02). We have previously reported that longer measured LTL was also associated with an increased risk of LUAD (Q4: 2.82 (1.16-6.85); p-trend=0.011). The combined effect of both a higher Alu/Alb ratio and longer LTL was 6.07 (1.75, 21.04; p=4.5x10-3) for LUAD compared with lower/shorter levels of both. Higher Alu copy number and longer LTL were associated with increased risk of lung cancer, especially LUAD. Our findings require replication. If confirmed, evaluation of Alu copy number and LTL in risk stratification and prediction analyses is warranted. Citation Format: Jason Yat-Yang Wong, Richard Cawthon, Wei Hu, Somayina Ezennia, Shahinaz Gadalla, Charles Breeze, Batel Blechter, Neal Freedman, Wen-Yi Huang, H. Dean Hosgood, Wei Jie Seow, Bryan Bassig, Mohammad Rahman, Richard Hayes, Nathaniel Rothman, Qing Lan. Alu retroelement copy number, leukocyte telomere length, and lung cancer risk in the prospective Prostate, Lung, Colorectal and Ovarian Cancer (PLCO) Screening Trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2251.

Background: The lung cancer rate for never-smoking women in Xuanwei, China, where coal is used extensively for home heating and cooking, is among the highest in the world. This excess is due almost entirely to household air pollution (HAP) from smoky (bituminous) coal used for home heating and cooking, which produces multiple toxic constituents including polycyclic aromatic hydrocarbons (PAHs). Alu retroelements, which are repetitive mobile DNA sequences that can multiply and affect genomic stability, have been associated with diesel engine exhaust exposure and prospectively linked to lung cancer risk. To explore the relationship between genotoxic carcinogens and Alu repeats, we assessed the association between HAP and Alu copy number. Methods: A cross-sectional study of 158 never-smoking women with repeat sampling of 48 subjects was conducted in Xuanwei, China. Quantitative PCR was used to measure Alu repeat copy number relative to albumin gene copy number (Alu/ALB ratio), reflecting the average quantity of Alu repeats per cell, in white blood cell DNA. Exposure models were used to predict levels of current exposure to 43 individual household air pollutants. Hierarchical clustering of the air pollutants was conducted to address collinearity, and generalized estimating equations were used to take into account Alu copy number measured in repeat samples. Results: A cluster of 31 PAHs was associated with increased Alu copy number (β:0.03(95% confidence interval:0.01,0.04) per SD;P-value=0.001). One compound within this cluster, 5-methylchrysene, which has been associated with lung cancer risk in Xuanwei and was selected a priori for analysis, was also associated with increased Alu copy number (P-value=0.0097). Conclusions: Our findings suggest that exposure to PAHs from HAP due to household smoky coal combustion may contribute to genomic instability. Future work in larger studies and among those exposed to other types of coal, wood, and biomass combustion is warranted. KEYWORDS:Solid fuel use, Alu, PAHs

ABSTRACTIn both mice and humans the misexpression of many genes lacking CpG islands (CGI- genes) increases with age, promoting inflammation and degenerative changes (Lee et al. 2021, ref. 1). In light of this recent discovery, we have revisited and expanded upon our previous work on gene expressions vs. aging and mortality in the three-generation CEPH (Centre d’Etudes du Polymorphisme Humain) Utah (CEU) families (Kerber et al. 2009, ref. 2). That study examined gene expressions in lymphoblastoid cell lines (LCLs) established in the early 1980s from all three CEU generations, in relation to age at blood draw, and in relation to the long-term survival of the grandparent generation. The 2009 study did not, however, consider the CGI status of genes, and it excluded from analysis genes not expressed in all of the subjects; therefore, the contribution to variation in age-at-death of inter-individual variation in the misexpression of genes with increasing age was not investigated. For the current study, after categorizing genes by their CGI status (- or +), we now find that most CGI- gene expressions in the LCLs increased with donor age, and after adjustment for donor age and sex, were positively associated with mortality risks. In contrast, most CGI+ gene expressions decreased with donor age, with higher expressions associated with decreased mortality risks. Of 7025 genes with known CGI status with expression detected in sufficient numbers of subjects from the grandparent generation to allow testing of association with mortality, 1834 genes were expressed in all subjects’ LCLs across all three generations, and 5191 were expressed in some, but not all subjects. We found the set of “not always expressed” genes to be highly enriched for CGI- genes. Furthermore, 49.4% of the CGI- genes were never expressed from ages 0-14, but expressed sometimes or always at older ages; in contrast, only 22.3% of the CGI+ genes were never expressed from ages 0-14, but expressed at older ages. These data support the model proposed by Lee et al. 2021, whereby tissue-restricted CGI- gene expressions become increasingly misexpressed during aging, contributing to loss of cellular identity, multiple aging-related pathologies, and ultimately death.

Background Millions of workers worldwide are exposed to diesel engine exhaust (DEE), a known genotoxic carcinogen. Alu retroelements are repetitive DNA sequences that can multiply and compromise genomic stability. There is some evidence linking altered Alu repeats to cancer and elevated mortality risks. However, whether Alu repeats are influenced by environmental pollutants is unexplored. In an occupational setting with high DEE exposure levels, we investigated associations with Alu repeat copy number. Methods A cross-sectional study of 54 male DEE-exposed workers from an engine testing facility and a comparison group of 55 male unexposed controls was conducted in China. Personal air samples were assessed for elemental carbon, a DEE surrogate, using NIOSH Method 5040. Quantitative PCR (qPCR) was used to measure Alu repeat copy number relative to albumin (Alb) single-gene copy number in leucocyte DNA. The unitless Alu/Alb ratio reflects the average quantity of Alu repeats per cell. Linear regression models adjusted for age and smoking status were used to estimate relations between DEE-exposed workers versus unexposed controls, DEE tertiles (6.1-39.0, 39.1-54.5 and 54.6-107.7 mu g/m(3)) and Alu/Alb ratio. Results DEE-exposed workers had a higher average Alu/Alb ratio than the unexposed controls (p=0.03). Further, we found a positive exposure-response relationship (p=0.02). The Alu/Alb ratio was highest among workers exposed to the top tertile of DEE versus the unexposed controls (1.12 +/- 0.08 SD vs 1.06 +/- 0.07 SD, p=0.01). Conclusion Our findings suggest that DEE exposure may contribute to genomic instability. Further investigations of environmental pollutants, Alu copy number and carcinogenesis are warranted.

Background: Leukocyte telomere length (LTL) has been associated with risk of multiple cancers, but its association with pancreatic ductal adenocarcinoma (PDAC) is unclear. We therefore investigated the association between peripheral blood LTL and PDAC risk, and examined effect modification by candidate SNPs previously reported to be associated with variation in LTL. Methods: A case–control study of 1,460 PDAC cases and 1,459 frequency-matched controls was performed using biospecimens and data from the Mayo Clinic Biospecimen Resource for Pancreas Research. Quantitative PCR was used to measure LTL and categorized into tertiles based on sex-specific control distribution. Eleven telomere-related SNPs also were genotyped. Logistic regression was used to calculate ORs and 95% confidence intervals (CI). Results: Shorter peripheral blood LTL was associated with a higher risk of PDAC (ORT1vsT3 = 1.26, 95% CI = 1.03–1.54, Ptrend = 0.02; ORcontinuous = 1.14, 95% CI = 1.02–1.28), but the association was restricted to cases with treatment-naïve blood samples (ORT1vsT3 = 1.51, 95% CI = 1.16–1.96, Ptrend = 0.002; ORcontinuous = 1.25, 95% CI = 1.08–1.45) and not cases whose blood samples were collected after initiation of cancer therapy (ORT1vsT3 = 1.10, 95% CI = 0.87–1.39, Ptrend = 0.42; ORcontinuous = 1.08, 95% CI = 0.94–1.23). Three SNPs (TERC-rs10936599, ACYP2-rs11125529, and TERC-rs1317082) were each associated with interindividual variation in LTL among controls, but there was no evidence of effect modification by these SNPs. Conclusions: Treatment-naïve short LTL is associated with a higher risk of PDAC, and the association does not differ by germline variation in the candidate telomere-related SNPs examined. Impact: Peripheral blood LTL might serve as a molecular marker for risk modeling to identify persons at high risk of PDAC.

BACKGROUND:Critically shortened telomeres contribute to chromosomal instability and neoplastic transformation and are associated with early death of patients with certain cancer types. Shorter leukocyte telomere length (LTL) has been associated with higher risk for pancreatic ductal adenocarcinoma (PDAC) and might be associated also with survival of patients with PDAC. We investigated the association between treatment-naïve LTL and overall survival of patients with incident PDAC. METHODS:The study included 642 consecutively enrolled PDAC patients in the Mayo Clinic Biospecimen Resource for Pancreas Research. Blood samples were obtained at the time of diagnosis, before the start of cancer treatment, from which LTL was assayed by qRT-PCR. LTL was first modeled as a continuous variable (per-interquartile range decrease in LTL) and then as a categorized variable (short, medium, long). Multivariable-adjusted HRs and 95% confidence intervals (CI) were calculated for overall mortality using Cox proportional hazard models. RESULTS:Shorter treatment-naïve LTL was associated with higher mortality among patients with PDAC (HRcontinuous = 1.13, 95% CI: 1.01-1.28, P = 0.03; HRshortest vs. longest LTL = 1.29, 95% CI: 1.05-1.59, P trend = 0.01). There was a difference in the association between LTL and overall mortality by tumor stage at diagnosis; resectable tumors (HRcontinuous = 0.91; 95% CI: 0.73-1.12), locally advanced tumors (HRcontinuous = 1.29; 95% CI: 1.07-1.56), and metastatic tumors (HRcontinuous = 1.17; 95% CI: 0.96-1.42), P interaction = 0.04. CONCLUSION:Shorter treatment-naïve LTL is associated with poorer overall survival of patients with incident PDAC. IMPACT:Peripheral blood LTL might be a prognostic marker for PDAC.

Ageing may be due to mutation accumulation across the lifespan, leading to tissue dysfunction, disease, and death. We tested whether germline autosomal mutation rates in young adults predict their remaining survival, and, for women, their reproductive lifespans. Age-adjusted mutation rates (AAMRs) in 61 women and 61 men from the Utah CEPH (Centre d’Etude du Polymorphisme Humain) families were determined. Age at death, cause of death, all-site cancer incidence, and reproductive histories were provided by the Utah Population Database, Utah Cancer Registry, and Utah Genetic Reference Project. Higher AAMRs were significantly associated with higher all-cause mortality in both sexes combined. Subjects in the top quartile of AAMRs experienced more than twice the mortality of bottom quartile subjects (hazard ratio [HR], 2.07; 95% confidence interval [CI], 1.21–3.56; p = 0.008; median survival difference = 4.7 years). Fertility analyses were restricted to women whose age at last birth (ALB) was ≥ 30 years, the age when fertility begins to decline. Women with higher AAMRs had significantly fewer live births and a younger ALB. Adult germline mutation accumulation rates are established in adolescence, and later menarche in women is associated with delayed mutation accumulation. We conclude that germline mutation rates in healthy young adults may provide a measure of both reproductive and systemic ageing. Puberty may induce the establishment of adult mutation accumulation rates, just when DNA repair systems begin their lifelong decline.

Quantitative PCR is frequently used to measure average telomere length (TL) relative to the TL of a reference DNA sample of the investigator’s choosing. This makes comparisons of TLs across studies and laboratories difficult. Here we demonstrate that a single synthetic single-stranded dual-template oligonucleotide (DTO) containing both a telomere repeat sequence (T) and a segment of the human beta-globin (HBB) single copy gene (S) can be used as a universal reference standard for monochrome multiplex quantitative PCR (MMqPCR) measurements of average TL using SYBR Green I as the only fluorescent reporter dye. A set of twelve concentrations of the DTO is prepared by serial 3-fold dilutions, to a lowest concentration of ~20 copies per μl. The 5 highest concentrations are used for the T standard curve, and the 5 lowest concentrations are used for the S standard curve. For each reaction 5 μl containing approximately 3 ng of genomic DNA (or one of the DTO dilutions) is mixed with 5 μl of a 2x MasterMix containing the primers for T and S amplification, and MMqPCR is performed. The design of the primers and thermal cycling profile allows all T amplification signals to be collected before exponential amplification of the S signal begins. Exponential amplification from S is then carried out in a temperature range that keeps the telomere product fully melted and therefore unable to influence the S amplification signal. The T value for each DNA sample is the Standard Curve DTO dilution that contains the same number of copies of the telomere sequence as the experimental sample, and the S value is the DTO dilution that contains the same number of copies of the single copy gene sequence as the experimental sample. Dividing the first dilution by the second dilution yields an absolute T/S ratio, since it is expressed relative to the fixed 1:1 T/S ratio that is built into the DTO by design. Absolute T/S ratios for average TL in 48 human DNA samples determined by this method correlated strongly with mean Terminal Restriction Fragment (mTRF) lengths for the same DNA samples determined by the Southern Blot method (R-squared = 0.801). This DTO and the accompanying protocol may facilitate the standardization of average telomere length measurements and analyses across laboratories.

OPS 44: Occupational health studies with environmental implications, Room 411, Floor 4, August 27, 2019, 4:30 PM - 5:30 PM Background/Aim: Millions of transportation and industrial workers worldwide are exposed to diesel engine exhaust (DEE), an established lung carcinogen that contains DNA-damaging constituents. Alu retroelements are repetitive DNA sequences that can multiply, insert throughout the genome, and disrupt gene expression and genomic architecture. Site-specific DNA strand breaks activate Alu retrotransposition and altered Alu repeats have been linked to cancer and mortality risk. However, whether Alu retroelements are influenced by environmental pollutants is largely unexplored. In an occupational setting with high levels of DEE, we investigated associations between personal exposure and Alu copy-number. Methods: A cross-sectional study was conducted in China with 54 DEE-exposed male workers from an engine testing facility and 55 unexposed male controls. Personal air samples were measured for elemental carbon (EC), a DEE surrogate, using NIOSH Method 5040. Leukocyte DNA was extracted from blood samples and quantitative polymerase chain reaction was used to measure Alu copy-number relative to albumin (Alb) single gene copy-number. The unitless Alu/Alb ratio reflects the average Alu copy-number. Linear regression models were used to test for differences in Alu/Alb ratio between controls and DEE-exposed workers, and to evaluate exposure–response relationships across DEE-exposure groups (i.e., controls and EC-tertiles: 6.1–39.0, 39.1–54.5, and 54.6–107.7 µg/m3) adjusted for age and smoking status. Results: DEE-exposed workers had a higher Alu/Alb ratio than unexposed controls (p=0.03). Further, we found a positive exposure-response relationship with EC (p-trend=0.02). The Alu/Alb ratio was largest among DEE-exposed workers in the highest EC-tertile versus controls (1.12+/-0.08 SD versus 1.06+/-0.07 SD, p=0.01). Age, body mass index, smoking, and work years were not associated with Alu/Alb ratio. Conclusions: Our findings suggest that increased levels of DEE exposure may contribute to genomic instability, possibly reflected by Alu copy-number. Further studies are needed to evaluate the influence of environmental pollutants on Alu copy-number in relation to carcinogenesis.