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Li M, Yang K, De Vivo I, Eliassen AH, Qureshi AA, Nan H, Han J. Association between plasma L-carnitine levels and mitochondrial DNA copy number. BMC Mol Cell Biol 2023; 24:35. [PMID: 38082229 PMCID: PMC10712069 DOI: 10.1186/s12860-023-00496-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Accepted: 12/06/2023] [Indexed: 12/18/2023] Open
Abstract
Mitochondria are key cytoplasmic organelles in eukaryotic cells that generate adenosine triphosphate (ATP) through the electron transport chain and oxidative phosphorylation. Mitochondrial DNA (mtDNA) copy number (mtDNAcn) is considered a biomarker for both mitochondrial quantity and function as well as cellular oxidative stress level. Previous epidemiologic findings revealed that weight gain, higher body mass index (BMI), smoking, and high insulinemic potential of lifestyle were associated with lower leukocyte mtDNAcn. Carnitines are a group of compounds that play a critical role in energy production. We quantified the associations of plasma L-carnitine levels with leukocyte mtDNAcn. We then examined the association between mtDNAcn and L-carnitine (HMDB0000062) in 538 U.S. men without cancers, diabetes, or cardiovascular disease at blood collection from the Health Professionals Follow-Up Study (HPFS). We found a significant inverse association between L-carnitine and mtDNAcn (ρ = -0.1, P = 0.02). This implies that the carnitine metabolic pathway may be associated with mitochondrial function and oxidative stress.
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Affiliation(s)
- Mingyue Li
- Department of Epidemiology, Richard M. Fairbanks School of Public Health, Indiana University, 1050 Wishard Boulevard, RG 6124, Indianapolis, IN, 46202-2872, USA
| | - Keming Yang
- Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
- Clinical and Translational Epidemiology Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Immaculata De Vivo
- Department of Medicine, Harvard Medical School, Boston, MA, USA
- Channing Division of Network Medicine, Brigham and Women's Hospital, Boston, MA, USA
- Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA
- Program in Genetic Epidemiology and Statistical Genetics, Harvard School of Public Health, Boston, MA, USA
| | - A Heather Eliassen
- Department of Medicine, Harvard Medical School, Boston, MA, USA
- Channing Division of Network Medicine, Brigham and Women's Hospital, Boston, MA, USA
- Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA
- Department of Nutrition, Harvard School of Public Health, Boston, MA, USA
| | - Abrar A Qureshi
- Warren Alpert Medical School, Brown University, Providence, RI, USA
| | - Hongmei Nan
- Department of Epidemiology, Richard M. Fairbanks School of Public Health, Indiana University, 1050 Wishard Boulevard, RG 6124, Indianapolis, IN, 46202-2872, USA
- Department of Global Health, Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA
| | - Jiali Han
- Department of Epidemiology, Richard M. Fairbanks School of Public Health, Indiana University, 1050 Wishard Boulevard, RG 6124, Indianapolis, IN, 46202-2872, USA.
- Department of Global Health, Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA.
- Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, IN, USA.
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Campolo J, Borghini A, Parolini M, Mercuri A, Turchi S, Andreassi MG. Clinical and Biological Predictors of Cancer Incidence and Mortality in Patients with Stable Coronary Artery Disease. Int J Mol Sci 2023; 24:11091. [PMID: 37446269 DOI: 10.3390/ijms241311091] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 06/29/2023] [Indexed: 07/15/2023] Open
Abstract
Clinical and epidemiological evidence has recently revealed a link between coronary artery disease (CAD) and cancer. Shared risk factors and common biological pathways are probably involved in both pathological conditions. The aim of this paper was to evaluate whether and which conventional risk factors and novel circulating biomarkers could predict cancer incidence and death in patients with CAD. The study included 750 CAD patients, who underwent blood sampling for the evaluation of systemic inflammatory indexes (NLR and SII) and specific biomarkers of oxidative damage (leukocyte telomere length (LTL), mitochondrial DNA copy number (mtDNAcn)). Study participants were followed up for a mean of 5.4 ± 1.2 years. Sixty-seven patients (8.9%) developed cancer during the follow-up time, and nineteen (2.5%) died of cancer. Cox multivariable analysis revealed that age (HR = 1.071; 95% CI: 1.034-1.109; p < 0.001), smoking habit (HR = 1.994; 95% CI: 1.140-3.488; p = 0.016), obesity (HR = 1.708; 95% CI: 1.022-2.854; p = 0.041) and SII (HR = 1.002; 95% CI: 1.001-1.003; p = 0.045) were associated with cancer incidence, while only age (HR = 1.132; 95% CI: 1.052-1.219; p = 0.001) was a predictor of cancer death. Patients with lung and gastrointestinal cancers had significantly higher median mtDNAcn levels than those without cancer. Our study suggests that aggressive risk factor modification and suppression of chronic inflammation may be essential to preventing cancer in CAD patients.
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Affiliation(s)
- Jonica Campolo
- CNR Institute of Clinical Physiology, ASST Grande Ospedale Metropolitano Niguarda, 20162 Milan, Italy
| | | | - Marina Parolini
- CNR Institute of Clinical Physiology, ASST Grande Ospedale Metropolitano Niguarda, 20162 Milan, Italy
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Memon AA, Vats S, Sundquist J, Li Y, Sundquist K. Mitochondrial DNA Copy Number: Linking Diabetes and Cancer. Antioxid Redox Signal 2022; 37:1168-1190. [PMID: 36169625 DOI: 10.1089/ars.2022.0100] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Recent Advances: Various studies have suggested that mitochondrial DNA copy number (mtDNA-CN), a surrogate biomarker of mitochondrial dysfunction, is an easily quantifiable biomarker for chronic diseases, including diabetes and cancer. However, current knowledge is limited, and the results are controversial. This has been attributed mainly to methodology and study design. Critical Issues: The incidence of diabetes and cancer has increased significantly in recent years. Moreover, type 2 diabetes (T2D) has been shown to be a risk factor for cancer. mtDNA-CN has been associated with both T2D and cancer. However, it is not known whether mtDNA-CN plays any role in the association between T2D and cancer. Significance: In this review, we have discussed mtDNA-CN in diabetes and cancer, and reviewed the literature and methodology used in published studies so far. Based on the literature review, we have speculated how mtDNA-CN may act as a link between diabetes and cancer. Furthermore, we have provided some recommendations for reliable translation of mtDNA-CN as a biomarker. Future Directions: Further research is required to elucidate the role of mtDNA-CN in the association between T2D and cancer. If established, early lifestyle interventions, such as physical activity and diet control that improve mitochondrial function, may help preventing cancer in patients with T2D. Antioxid. Redox Signal. 37, 1168-1190.
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Affiliation(s)
- Ashfaque A Memon
- Center for Primary Health Care Research, Lund University/Region Skåne, Malmö, Sweden
| | - Sakshi Vats
- Center for Primary Health Care Research, Lund University/Region Skåne, Malmö, Sweden
| | - Jan Sundquist
- Center for Primary Health Care Research, Lund University/Region Skåne, Malmö, Sweden
| | - Yanni Li
- Center for Primary Health Care Research, Lund University/Region Skåne, Malmö, Sweden
| | - Kristina Sundquist
- Center for Primary Health Care Research, Lund University/Region Skåne, Malmö, Sweden
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Mori KM, McElroy JP, Weng DY, Chung S, Fadda P, Reisinger SA, Ying KL, Brasky TM, Wewers MD, Freudenheim JL, Shields PG, Song MA. Lung mitochondrial DNA copy number, inflammatory biomarkers, gene transcription and gene methylation in vapers and smokers. EBioMedicine 2022; 85:104301. [PMID: 36215783 PMCID: PMC9561685 DOI: 10.1016/j.ebiom.2022.104301] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 08/31/2022] [Accepted: 09/21/2022] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Mitochondrial DNA copy number (mtCN) maintains cellular function and homeostasis, and is linked to nuclear DNA methylation and gene expression. Increased mtCN in the blood is associated with smoking and respiratory disease, but has received little attention for target organ effects for smoking or electronic cigarette (EC) use. METHODS Bronchoscopy biospecimens from healthy EC users, smokers (SM), and never-smokers (NS) were assessed for associations of mtCN with mtDNA point mutations, immune responses, nuclear DNA methylation and gene expression using linear regression. Ingenuity pathway analysis was used for enriched pathways. GEO and TCGA respiratory disease datasets were used to explore the involvement of mtCN-associated signatures. FINDINGS mtCN was higher in SM than NS, but EC was not statistically different from either. Overall there was a negative association of mtCN with a point mutation in the D-loop but no difference within groups. Positive associations of mtCN with IL-2 and IL-4 were found in EC only. mtCN was significantly associated with 71,487 CpGs and 321 transcripts. 263 CpGs were correlated with nearby transcripts for genes enriched in the immune system. EC-specific mtCN-associated-CpGs and genes were differentially expressed in respiratory diseases compared to controls, including genes involved in cellular movement, inflammation, metabolism, and airway hyperresponsiveness. INTERPRETATION Smoking may elicit a lung toxic effect through mtCN. While the impact of EC is less clear, EC-specific associations of mtCN with nuclear biomarkers suggest exposure may not be harmless. Further research is needed to understand the role of smoking and EC-related mtCN on lung disease risks. FUNDING The National Cancer Institute, the National Heart, Lung, and Blood Institute, the Food and Drug Administration Center for Tobacco Products, the National Center For Advancing Translational Sciences, and Pelotonia Intramural Research Funds.
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Affiliation(s)
- Kellie M Mori
- Division of Environmental Health Sciences, College of Public Health, The Ohio State University, Columbus, OH, United States
| | - Joseph P McElroy
- Comprehensive Cancer Center, The Ohio State University and James Cancer Hospital, Columbus, OH, United States
| | - Daniel Y Weng
- Comprehensive Cancer Center, The Ohio State University and James Cancer Hospital, Columbus, OH, United States
| | - Sangwoon Chung
- Pulmonary and Critical Care Medicine, Department of Internal Medicine, The Ohio State University, Columbus, OH, United States
| | - Paolo Fadda
- Genomics Shared Resource, The Ohio State University and James Cancer Hospital, Columbus, OH, United States
| | - Sarah A Reisinger
- Comprehensive Cancer Center, The Ohio State University and James Cancer Hospital, Columbus, OH, United States
| | - Kevin L Ying
- Comprehensive Cancer Center, The Ohio State University and James Cancer Hospital, Columbus, OH, United States
| | - Theodore M Brasky
- Comprehensive Cancer Center, The Ohio State University and James Cancer Hospital, Columbus, OH, United States
| | - Mark D Wewers
- Pulmonary and Critical Care Medicine, Department of Internal Medicine, The Ohio State University, Columbus, OH, United States
| | - Jo L Freudenheim
- Department of Epidemiology and Environmental Health, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
| | - Peter G Shields
- Comprehensive Cancer Center, The Ohio State University and James Cancer Hospital, Columbus, OH, United States.
| | - Min-Ae Song
- Division of Environmental Health Sciences, College of Public Health, The Ohio State University, Columbus, OH, United States.
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Trudel-Fitzgerald C, Zevon ES, Kawachi I, Tucker-Seeley RD, Kubzansky LD. Depression, smoking, and lung cancer risk over 24 years among women. Psychol Med 2022; 52:2510-2519. [PMID: 33267930 PMCID: PMC9173857 DOI: 10.1017/s0033291720004390] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Studies evaluating depression's role in lung cancer risk revealed contradictory findings, partly because of the small number of cases, short follow-up periods, and failure to account for key covariates including smoking exposure. We investigated the association of depressive symptoms with lung cancer risk in a large prospective cohort over 24 years while considering the role of smoking. METHODS Women from the Nurses' Health Study completed measures of depressive symptoms, sociodemographics, and other factors including smoking in 1992 (N = 42 913). Depressive symptoms were also queried in 1996 and 2000, whereas regular antidepressant use and physician-diagnosed depression were collected starting in 1996. Multivariable Cox regression models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) of lung cancer risk until 2016. RESULTS We identified 1009 cases of lung cancer. Women with the highest v. lowest level of depressive symptoms had an increased lung cancer risk (HRsociodemographics-adjusted = 1.62, 95% CI 1.34-1.95; HRfully-adjusted = 1.25, 95% CI 1.04-1.51). In a test of mediation, lifetime pack-years of smoking accounted for 38% of the overall association between depressive symptoms and disease risk. When stratifying by smoking status, the elevated risk was evident among former smokers but not current or never smokers; however, the interaction term suggested no meaningful differences across groups (p = 0.29). Results were similar or stronger when considering time-updated depression status (using depressive symptoms, physician diagnosis, and regular antidepressant use) and chronicity of depressive symptoms. CONCLUSIONS These findings suggest that greater depressive symptoms may contribute to lung cancer incidence, directly and indirectly via smoking habits, which accounted for over a third of the association.
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Affiliation(s)
- Claudia Trudel-Fitzgerald
- Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA 02115
| | - Emily S. Zevon
- Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA 02115
| | - Ichiro Kawachi
- Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA 02115
| | - Reginald D. Tucker-Seeley
- Leonard Davis School of Gerontology, University of Southern California, 3715 McClintock Avenue, Los Angeles, CA 90089
| | - Laura D. Kubzansky
- Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA 02115
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Giaccherini M, Gentiluomo M, Fornili M, Lucenteforte E, Baglietto L, Campa D. Association between telomere length and mitochondrial copy number and cancer risk in humans: A meta-analysis on more than 300,000 individuals. Crit Rev Oncol Hematol 2021; 167:103510. [PMID: 34695574 DOI: 10.1016/j.critrevonc.2021.103510] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 10/13/2021] [Accepted: 10/14/2021] [Indexed: 12/17/2022] Open
Abstract
In the last decades the association of leukocyte telomere length (LTL) and mitochondrial copy number (mtDNAcn) with cancer risk has been the focus of many reports, however the relation is not yet completely understood. A meta-analysis of 112 studies including 64,184 cancer cases and 278,641 controls that analysed LTL and mtDNAcn in relation to cancer risk has been conducted to further our understanding of the topic. Stratified analyses for tumor type were also performed. Overall, no association was observed for all cancer combined neither for LTL nor mtDNAcn. Significant associations were detected for these biomarkers and specific cancer type; however, a large degree of heterogeneity was present, even within the same tumor type. Alternatives approaches based on polymorphic variants, such as polygenic risk scores and mendelian randomization, could be adopted to unravel the causal correlation of telomere length and mitochondrial copy number with cancer risk.
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Affiliation(s)
| | | | - Marco Fornili
- Department of Clinical and Experimental Medicine, University of Pisa, 56126, Pisa, Italy.
| | - Ersilia Lucenteforte
- Department of Clinical and Experimental Medicine, University of Pisa, 56126, Pisa, Italy.
| | - Laura Baglietto
- Department of Clinical and Experimental Medicine, University of Pisa, 56126, Pisa, Italy.
| | - Daniele Campa
- Department of Biology, University of Pisa, 56126, Pisa, Italy.
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7
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Yang K, Forman MR, Monahan PO, Graham BH, Chan AT, Zhang X, De Vivo I, Giovannucci EL, Tabung FK, Nan H. Insulinemic Potential of Lifestyle Is Inversely Associated with Leukocyte Mitochondrial DNA Copy Number in US White Adults. J Nutr 2020; 150:2156-2163. [PMID: 32492151 PMCID: PMC7398789 DOI: 10.1093/jn/nxaa146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/18/2020] [Accepted: 05/01/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Poor lifestyles have been linked to insulin insensitivity/hyperinsulinemia, which may contribute to downstream changes such as inflammation and oxidative damage and the development of chronic diseases. As a biomarker of intracellular oxidative stress, leukocyte mitochondrial DNA copy number (mtDNA-CN) has been related to lifestyle factors including diet and weight. No epidemiologic study has examined the relation between combined insulinemic potential of lifestyle and mtDNA-CN. OBJECTIVES Our aim was to examine the association between Empirical Lifestyle Index for Hyperinsulinemia (ELIH) and leukocyte mtDNA-CN in US men and women. METHODS This cross-sectional analysis included 2835 white adults without cancers, diabetes, or cardiovascular disease at blood collection, including 2160 women from the Nurses' Health Study and 675 men from the Health Professionals Follow-Up Study. ELIH is an index based on plasma C-peptide that characterizes the insulinemic potential of lifestyle (diet, body weight, and physical activity). Relative mtDNA-CN in peripheral blood leukocytes was measured by qPCR-based assay. RESULTS We found a significant inverse association between ELIH and mtDNA-CN. In multivariable-adjusted linear models, absolute least squares means ± SDs of mtDNA-CN z score across ELIH quintiles in women were as follows: Q1: 0.14 ± 0.05; Q2: 0.04 ± 0.06; Q3: 0.008 ± 0.05; Q4: 0.01 ± 0.05; and Q5: -0.06 ± 0.05 (P-trend = 0.006). Means ± SDs in men were as follows: Q1: 0.25 ± 0.09; Q2: 0.23 ± 0.09; Q3: 0.07 ± 0.09; Q4: 0.02 ± 0.09; and Q5: -0.04 ± 0.09 (P-trend = 0.007). Means ± SDs in all participants were as follows: Q1: 0.16 ± 0.05; Q2: 0.07 ± 0.05; Q3: 0.01 ± 0.05; Q4: 0.01 ± 0.05; and Q5: -0.05 ± 0.05 (P-trend = 0.0004). CONCLUSIONS Hyperinsulinemic lifestyles (i.e., higher ELIH) were associated with lower leukocyte mtDNA-CN among subjects without major diseases, suggesting that the difference in lifestyle insulinemic potential may be related to excessive oxidative stress damage.
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Affiliation(s)
- Keming Yang
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA,Department of Epidemiology, Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA
| | - Michele R Forman
- Department of Nutrition Science, College of Health and Human Science, Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, USA
| | - Patrick O Monahan
- Department of Biostatistics, School of Medicine and Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA
| | - Brett H Graham
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Andrew T Chan
- Clinical and Translational Epidemiology Unit and Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA,Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Xuehong Zhang
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA,Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Immaculata De Vivo
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA,Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Edward L Giovannucci
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA,Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA,Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Fred K Tabung
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA,Department of Internal Medicine, The Ohio State University College of Medicine and Comprehensive Cancer Center, Columbus, OH, USA,Address correspondence to FKT (e-mail: )
| | - Hongmei Nan
- Department of Epidemiology, Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA,Department of Global Health, Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA,IU Melvin and Bren Simon Cancer Center, Indiana University, Indianapolis, IN, USA,Address correspondence to HN (e-mail: )
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Wang X, Hart JE, Liu Q, Wu S, Nan H, Laden F. Association of particulate matter air pollution with leukocyte mitochondrial DNA copy number. ENVIRONMENT INTERNATIONAL 2020; 141:105761. [PMID: 32388147 PMCID: PMC7419671 DOI: 10.1016/j.envint.2020.105761] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 04/07/2020] [Accepted: 04/22/2020] [Indexed: 05/22/2023]
Abstract
BACKGROUND Ambient particulate matter (PM) has been associated with mitochondrial damage and dysfunction caused by excessive oxidative stress, but the associations between long-term PM exposure and leukocyte mitochondrial DNA copy number (mtDNAcn), a biomarker of mitochondrial dysfunction due to oxidative stress, are less studied. OBJECTIVES To investigate the associations between short-, intermediate- and long-term exposure (1-, 3- and 12-months) to different size fractions of PM (PM2.5, PM2.5-10 and PM10) and leukocyte mtDNAcn in a cross-sectional study. METHODS The associations between each of the PM exposure metrics with z scores of log-transformed mtDNAcn were examined using generalized linear regression models in 2758 female participants from the Nurses' Health Study (NHS). Monthly exposures to PM were estimated from spatio-temporal prediction models matched to each participants' address history. Potential effect modification by selected covariates was examined using multiplicative interaction terms and subgroup analyses. RESULTS In single-size fraction models, increases in all size fractions of PM were associated with decreases in mtDNAcn, although only models with longer averages of PM2.5 reached statistical significance. For example, an interquartile range (IQR) increase in 12-month average ambient PM2.5 (5.5 μg/m3) was associated with a 0.07 [95% confidence interval (95% CI): -0.13, -0.01; p-value = 0.02] decrease in mtDNAcn z score in both basic- and multivariable-adjusted models. Associations for PM2.5 were stronger after controlling for PM2.5-10 in two size-fraction models. CONCLUSIONS Our study suggests that long-term exposure to ambient PM2.5 is associated with decreased mtDNAcn in healthy women.
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Affiliation(s)
- Xinmei Wang
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing, China
| | - Jaime E Hart
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA; Exposure, Epidemiology and Risk Program, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Qisijing Liu
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing, China
| | - Shaowei Wu
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing, China; Key Laboratory of Molecular Cardiovascular Sciences, Peking University, Ministry of Education, China.
| | - Hongmei Nan
- Department of Epidemiology, Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA; Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, IN, USA
| | - Francine Laden
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA; Exposure, Epidemiology and Risk Program, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
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Thakur N, Sharma AK, Singh H, Singh S. Role of Mitochondrial DNA (mtDNA) Variations in Cancer Development: A Systematic Review. Cancer Invest 2020; 38:375-393. [PMID: 32673136 DOI: 10.1080/07357907.2020.1797768] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
mtDNA is the closed circular, ds-DNA present in mitochondria of eukaryotic cells and are inherited maternally. Besides being the power house of the cell, mitochondria are also responsible for the regulation of redox homeostasis, signaling, metabolism, immunity, survival and apoptosis. Lack of a 'Systematic Review' on mtDNA variations and cancers encouraged us to perform the present study. Pubmed', 'Embase' and 'Cochrane Library' databases were searched using keywords 'Mitochondrial DNA' OR 'mtDNA' OR 'mDNA' AND 'polymorphism' AND 'cancer' AND 'risk' to retrieve literature. Polymorphisms occupy first rank among mtDNA variations followed by CNV, MSI, mutations and hold a great potential to emerge as key predictors for human cancers.
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Affiliation(s)
- Nisha Thakur
- Division of Molecular Diagnostics, Indian Council of Medical Research (ICMR)-National Institute of Cancer Prevention and Research (NICPR), Ministry of Health & Family Welfare (Govt. of India), Noida, India
| | - Amitesh Kumar Sharma
- Division of Informatics, Systems Research and Management, Indian Council of Medical Research (ICMR), Ministry of Health & Family Welfare (Govt. of India), New Delhi, India
| | - Harpreet Singh
- Division of Informatics, Systems Research and Management, Indian Council of Medical Research (ICMR), Ministry of Health & Family Welfare (Govt. of India), New Delhi, India
| | - Shalini Singh
- Indian Council of Medical Research (ICMR)-National Institute of Cancer Prevention and Research (NICPR), Ministry of Health & Family Welfare (Govt. of India), Noida, India
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Keller A, Fehlmann T, Backes C, Kern F, Gislefoss R, Langseth H, Rounge TB, Ludwig N, Meese E. Competitive learning suggests circulating miRNA profiles for cancers decades prior to diagnosis. RNA Biol 2020; 17:1416-1426. [PMID: 32456538 DOI: 10.1080/15476286.2020.1771945] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
MicroRNAs are regulators of gene expressionand may be key markers in liquid biopsy.Early diagnosis is an effective means to increase patients' overall survival. We generated genome-wide miRNA profiles from serum of patients and controls from the population-based Janus Serum Bank (JSB) and analysed them by bioinformatics and artificial intelligence approaches. JSB contains sera from 318,628 originally healthy persons, more than 96,000 of whom developed cancer. We selected 210 serum samples from patients with lung, colon or breast cancer at three time points prior to diagnosis (up to 32 years prior to diagnosis with median 5 years interval between TPs), one time-point after diagnosis and from individually matched controls. The controls were matched on age and year of all pre-diagnostic sampling time-points for the corresponding case. Using ANOVA we report 70 significantly deregulated markers (adjusted p-value<0.05). The driver for the significance was the diagnostic time point (miR-575, miR-6821-5p, miR-630 with adjusted p-values<10-10). Further, 91miRNAs were differently expressed in pre-diagnostic samples as compared to controls (nominal p < 0.05). Self-organized maps (SOMs)indicated larges effects in lung cancer samples while breast cancer samples showed the least pronounced changes. SOMsalsohighlighted cancer and time point specific miRNA dys-regulation. Intriguingly, a detailed breakdown of the results highlighted that 51% of all miRNAs were highly specific, either for a time-point or a cancer entity. Pathway analysis highlighted 12 pathways including Hipo signalling and ABC transporters.Our results indicate that tumours may be indicated by serum miRNAs decades prior the clinical manifestation.
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Affiliation(s)
- Andreas Keller
- Department of Clinical Bioinformatics, Saarland University , Saarbrücken, Germany.,Department of Neurology and Neurological Sciences, Stanford University School of Medicine , Stanford, CA, USA
| | - Tobias Fehlmann
- Department of Clinical Bioinformatics, Saarland University , Saarbrücken, Germany
| | - Christina Backes
- Department of Clinical Bioinformatics, Saarland University , Saarbrücken, Germany
| | - Fabian Kern
- Department of Clinical Bioinformatics, Saarland University , Saarbrücken, Germany
| | - Randi Gislefoss
- Department of Research, Cancer Registry of Norway , Oslo, Norway
| | - Hilde Langseth
- Department of Research, Cancer Registry of Norway , Oslo, Norway.,Department of Epidemiology and Biostatistics, Imperial College London , London, UK
| | - Trine B Rounge
- Department of Research, Cancer Registry of Norway , Oslo, Norway.,Department of Informatics, University of Oslo , Oslo, Norway
| | - Nicole Ludwig
- Department of Human Genetics, Saarland University , Homburg/Saar, Germany
| | - Eckart Meese
- Department of Human Genetics, Saarland University , Homburg/Saar, Germany
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11
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Yang K, Li X, Forman MR, Monahan PO, Graham BH, Joshi A, Song M, Hang D, Ogino S, Giovannucci EL, De Vivo I, Chan AT, Nan H. Pre-diagnostic leukocyte mitochondrial DNA copy number and colorectal cancer risk. Carcinogenesis 2019; 40:1462-1468. [PMID: 31556446 PMCID: PMC7346713 DOI: 10.1093/carcin/bgz159] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/20/2019] [Accepted: 09/18/2019] [Indexed: 12/22/2022] Open
Abstract
Mitochondrial DNA (mtDNA) is susceptible to oxidative stress and mutation. Few epidemiological studies have assessed the relationship between mtDNA copy number (mtDNAcn) and risk of colorectal cancer (CRC), with inconsistent findings. In this study, we examined the association between pre-diagnostic leukocyte mtDNAcn and CRC risk in a case-control study of 324 female cases and 658 matched controls nested within the Nurses' Health Study (NHS). Relative mtDNAcn in peripheral blood leukocytes was measured by quantitative polymerase chain reaction-based assay. Conditional logistic regression models were applied to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) for the association of interest. Results showed lower log-mtDNAcn was significantly associated with increased risk of CRC, in a dose-dependent relationship (P for trend < 0.0001). Compared to the fourth quartile, multivariable-adjusted OR [95% confidence interval (CI)] was 1.10 (0.69, 1.76) for the third quartile, 1.40 (0.89, 2.19) for the second quartile and 2.19 (1.43, 3.35) for the first quartile. In analysis by anatomic subsite of CRC, we found a significant inverse association for proximal colon cancer [lowest versus highest quartile, multivariable-adjusted OR (95% CI) = 3.31 (1.70, 6.45), P for trend = 0.0003]. Additionally, stratified analysis according to the follow-up time since blood collection showed that the inverse association between mtDNAcn and CRC remained significant among individuals with ≥ 5 years' follow-up, and marginally significant among those with ≥ 10 years' follow-up since mtDNAcn testing, suggesting that mtDNAcn may serve as a long-term predictor for risk of CRC. In conclusion, pre-diagnostic leukocyte mtDNAcn was inversely associated with CRC risk. Further basic experimental studies are needed to explore the underlying biological mechanisms linking mtDNAcn to CRC carcinogenesis.
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Affiliation(s)
- Keming Yang
- Department of Epidemiology, Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA
| | - Xin Li
- Department of Epidemiology, Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA
| | - Michele R Forman
- Department of Nutrition Science, College of Health and Human Science, Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, USA
| | - Patrick O Monahan
- Department of Biostatistics, School of Medicine and Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA
| | - Bret H Graham
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Amit Joshi
- Clinical and Translational Epidemiology Unit and Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Mingyang Song
- Clinical and Translational Epidemiology Unit and Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Dong Hang
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Department of Epidemiology and Biostatistics, Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Shuji Ogino
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Program in MPE Molecular Pathological Epidemiology, Department of Pathology, Brigham and Women’s Hospital, and Harvard Medical School, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Edward L Giovannucci
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
| | - Immaculata De Vivo
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
| | - Andrew T Chan
- Clinical and Translational Epidemiology Unit and Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
| | - Hongmei Nan
- Department of Epidemiology, Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA
- IU Melvin and Bren Simon Cancer Center, Indiana University, Indianapolis, IN, USA
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12
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Wu S, Li X, Meng S, Fung T, Chan AT, Liang G, Giovannucci E, De Vivo I, Lee JH, Nan H. Fruit and vegetable consumption, cigarette smoke, and leukocyte mitochondrial DNA copy number. Am J Clin Nutr 2019; 109:424-432. [PMID: 30721920 PMCID: PMC6367969 DOI: 10.1093/ajcn/nqy286] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 09/21/2018] [Indexed: 12/11/2022] Open
Abstract
Background Mitochondrial dysfunction is an important component of the aging process and has been implicated in the development of many human diseases. Mitochondrial DNA copy number (mtDNAcn), an indirect biomarker of mitochondrial function, is sensitive to oxidative damage. Few population-based studies have investigated the impact of fruit and vegetable consumption and cigarette smoke (2 major sources of exogenous antioxidants and oxidants) on leukocyte mtDNAcn. Objectives We investigated the association between fruit and vegetable consumption, cigarette smoke, and leukocyte mtDNAcn based on data from the Nurses' Health Study (NHS). Methods Data from 2769 disease-free women in the NHS were used to examine the cross-sectional associations between dietary sources of antioxidants, cigarette smoke, and leukocyte mtDNAcn. In vitro cell-based experiments were conducted to support the findings from the population-based study. Results In the multivariable-adjusted model, both whole-fruit consumption and intake of flavanones (a group of antioxidants abundant in fruit) were positively associated with leukocyte mtDNAcn (P-trend = 0.005 and 0.02, respectively), whereas pack-years of smoking and smoking duration were inversely associated with leukocyte mtDNAcn (P-trend = 0.01 and 0.007, respectively). These findings are supported by in vitro cell-based experiments showing that the administration of naringin, a major flavanone in fruit, led to a substantial increase in mtDNAcn in human leukocytes, whereas exposure to nicotine-derived nitrosamine ketone, a key carcinogenic ingredient of cigarette smoke, resulted in a significant decrease in mtDNAcn of cells (all P < 0.05). Further in vitro studies showed that alterations in leukocyte mtDNAcn were functionally linked to the modulation of mitochondrial biogenesis and function. Conclusions Fruit consumption and intake of dietary flavanones were associated with increased leukocyte mtDNAcn, whereas cigarette smoking was associated with decreased leukocyte mtDNAcn, which is a promising biomarker for oxidative stress-related health outcomes.
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Affiliation(s)
- Shaowei Wu
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing, China
| | - Xin Li
- Department of Epidemiology, Richard M Fairbanks School of Public Health, Indiana University, Indianapolis, IN
| | | | - Teresa Fung
- Nutrition, Harvard TH Chan School of Public Health, Boston, MA
- Department of Nutrition, Simmons College, Boston, MA
| | - Andrew T Chan
- Channing Division of Network Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
- Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Geyu Liang
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, Jiangsu, China
| | - Edward Giovannucci
- Departments of Epidemiology
- Nutrition, Harvard TH Chan School of Public Health, Boston, MA
- Channing Division of Network Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
| | - Immaculata De Vivo
- Departments of Epidemiology
- Channing Division of Network Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
| | - Jin Hyup Lee
- Department of Food and Biotechnology
- Institutes of Natural Sciences, Korea University, Sejong, Republic of Korea
| | - Hongmei Nan
- Department of Epidemiology, Richard M Fairbanks School of Public Health, Indiana University, Indianapolis, IN
- Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, IN
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13
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Hang D, Nan H, Kværner AS, De Vivo I, Chan AT, Hu Z, Shen H, Giovannucci E, Song M. Longitudinal associations of lifetime adiposity with leukocyte telomere length and mitochondrial DNA copy number. Eur J Epidemiol 2018; 33:485-495. [PMID: 29619669 PMCID: PMC8063494 DOI: 10.1007/s10654-018-0382-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/20/2018] [Indexed: 12/12/2022]
Abstract
Adiposity may cause adverse health outcomes by increasing oxidative stress and systemic inflammation, which can be reflected by altered telomere length (TL) and mitochondrial DNA copy number (mtCN) in peripheral blood leukocytes. However, little is known about the influence of lifetime adiposity on TL and mtCN in later life. This study was performed to investigate the associations of lifetime adiposity with leukocyte TL and mtCN in 9613 participants from the Nurses' Health Study. A group-based trajectory modelling approach was used to create trajectories of body shape from age 5 through 60 years, and a genetic risk score (GRS) was created based on 97 known adiposity susceptibility variants. Associations of body shape trajectories and GRS with dichotomized TL and mtCN were assessed by logistic regression models. After adjustment for lifestyle and dietary factors, compared with the lean-stable group, the lean-marked increase group had higher odds of having below-median TL (OR = 1.18, 95% CI 1.04, 1.35; P = 0.01), and the medium-marked increase group had higher odds of having below-median mtCN (OR = 1.28, 95% CI 1.00, 1.64; P = 0.047). There was a suggestive trend toward lower mtCN across the GRS quartiles (P for trend = 0.07). In conclusion, telomere attrition may be accelerated by marked weight gain in middle life, whereas mtCN is likely to be reduced persistently by adiposity over the life course. The findings indicate the importance of lifetime weight management to preserve functional telomeres and mitochondria.
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Affiliation(s)
- Dong Hang
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Room 371, Bldg. 2, 665 Huntington Avenue, Boston, MA, 02115, USA
- Department of Epidemiology and Biostatistics, Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Hongmei Nan
- Department of Epidemiology, Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, IN, USA
- Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, IN, USA
| | - Ane Sørlie Kværner
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Room 371, Bldg. 2, 665 Huntington Avenue, Boston, MA, 02115, USA
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Immaculata De Vivo
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Andrew Tan Chan
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
- Clinical and Translational Epidemiology Unit and Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Room 906, 55 Fruit Street, Boston, MA, 02114, USA
| | - Zhibin Hu
- Department of Epidemiology and Biostatistics, Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Hongbing Shen
- Department of Epidemiology and Biostatistics, Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Edward Giovannucci
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Room 371, Bldg. 2, 665 Huntington Avenue, Boston, MA, 02115, USA.
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
| | - Mingyang Song
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Room 371, Bldg. 2, 665 Huntington Avenue, Boston, MA, 02115, USA.
- Clinical and Translational Epidemiology Unit and Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Room 906, 55 Fruit Street, Boston, MA, 02114, USA.
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14
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Quantification of mitochondrial DNA copy number in suspected cancer patients by a well optimized ddPCR method. BIOMOLECULAR DETECTION AND QUANTIFICATION 2017; 13:32-39. [PMID: 29021970 PMCID: PMC5634817 DOI: 10.1016/j.bdq.2017.08.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 07/21/2017] [Accepted: 08/04/2017] [Indexed: 12/22/2022]
Abstract
Changes in mitochondrial DNA (mtDNA) content is a useful clinical biomarker for various diseases, however results are controversial as several analytical factors can affect measurement of mtDNA. MtDNA is often quantified by taking ratio between a target mitochondrial gene and a reference nuclear gene (mtDNA/nDNA) using quantitative real time PCR often on two separate experiments. It measures relative levels by using external calibrator which may not be comparable across laboratories. We have developed and optimized a droplet digital PCR (ddPCR) based method for quantification of absolute copy number of both mtDNA and nDNA gene in whole blood. Finally, the role of mtDNA in suspected cancer patients referred to a cancer diagnostic center was investigated. Analytical factors which can result in false quantification of mtDNA have been optimized and both target and reference have been quantified simultaneously with intra- and inter-assay coefficient variances as 3.1% and 4.2% respectively. Quantification of mtDNA show that compared to controls, solid tumors (but not hematologic malignancies) and other diseases had significantly lower copy number of mtDNA. Higher mtDNA (highest quartile) was associated with a significantly lower risk of both solid tumors and other diseases, independent of age and sex. Receiver operating curve demonstrated that mtDNA levels could differentiate controls from patients with solid tumors and other diseases. Quantification of mtDNA by a well optimized ddPCR method showed that its depletion may be a hallmark of general illness and can be used to stratify healthy individuals from patients diagnosed with cancer and other chronic diseases.
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15
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Aberrant telomere length and mitochondrial DNA copy number in suicide completers. Sci Rep 2017; 7:3176. [PMID: 28600518 PMCID: PMC5466636 DOI: 10.1038/s41598-017-03599-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 05/02/2017] [Indexed: 11/16/2022] Open
Abstract
Short telomere length (TL) occurs in individuals under psychological stress, and with various psychiatric diseases. Recent studies have also reported mitochondrial DNA copy number (mtDNAcn) alterations under several neuropsychiatric conditions. However, no study has examined whether aberrant TL or mtDNAcn occur in completed suicide, one of the most serious outcomes of mental illnesses. TL and mtDNAcn in post-mortem samples from 528 suicide completers without severe physical illness (508 peripheral bloods; 20 brains) and 560 samples from control subjects (peripheral bloods from 535 healthy individuals; 25 post-mortem brains) were analysed by quantitative polymerase chain reaction. Suicide completers had significantly shorter TL and higher mtDNAcn of peripheral bloods with sex/age-dependent differences (shorter TL was more remarkably in female/young suicides; higher mtDNAcn more so in male/elderly suicides). The normal age-related decline of TL and mtDNAcn were significantly altered in suicide completers. Furthermore, shorter TL and lower mtDNAcn of post-mortem prefrontal cortex were seen in suicide completers compared to controls. This study shows the first association of aberrant telomeres and mtDNA content with suicide completion. Our results indicate that further research on telomere shortening and mitochondrial dysfunction may help elucidate the molecular underpinnings of suicide-related pathophysiology.
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