Oxidative stress, related blood cell DNA methylation and the development of cancer
Final Report Abstract
It has been shown in biological studies that excessive reactive oxygen species concentrations in cells are involved in carcinogenesis. However, there is a lack of population-based, prospective studies on the associations of biomarkers of the redox status and cancer incidence and the mechanisms of cancer development by redox signaling remains unsettled. Three urinary biomarkers were utilized to investigate the associations of oxidative stress with cancer risk based on the German ESTHER study (general population, age-range 50-75 years): 8-isoprostane, oxidized guanine/guanosine molecules and nitrite/nitrate concentrations. Urinary 8-isoprostane is the gold standard biomarker for the redox status of the human organism and it reflects the lipid peroxidation. Oxidized guanine/guanosine molecules, including 8-hydroxyguanine and its nucleoside forms, 8-hydroxy-2'-deoxyguanosine and 8-hydroxyguanosine reflect the oxidatively generated DNA/RNA damage. Nitrite and nitrate are the end-products of nitric oxide metabolism. Nitric oxide is an pro-inflammatory molecule and a mediator of signaling pathways which promote cancer progression and metastasis. Oxidized guanine/guanosine molecule and 8-isoprostane concentrations were measured from stored urine samples of 8,793 older adults of the ESTHER study, who were followed up for cancer incidence for 14 years. Nitrite/nitrate levels were measured in a nested case-control approach for n=245 incident lung cancer cases and n=735 controls from the same sample. Urinary nitrite/nitrate levels were statistically significantly associated with lung cancer incidence. Moreover, the urinary 8- isoprostane concentration was statistically significantly, positively associated with lung cancer, but not with colorectal, breast and prostate cancer. Oxidized guanine/guanosine molecule concentrations were not associated with any cancer site in the total population. However, colorectal cancer incidence statistically significantly increased by 8%, 9% and 8% per 1 standard deviation increase in oxidized guanine/guanosine molecule levels among current non-smokers, women and non-obese participants, respectively. In addition, the associations of two serum biomarkers of oxidative stress with common cancers were assessed in the ESTHER study and the Norwegian Tromsø study (both general population cohorts): Derivatives of reactive oxygen metabolite (D-ROM) levels and total thiol levels (TTL). D-ROMs are a battery of biomolecules generated by the oxidation of lipids, proteins and nucleic acids. Serum TTL are regarded as a biomarker of the antioxidant capacity because this biomarkers captures the concentration of free thiol groups of proteins in blood circulation, which can reversibly be oxidized. D-ROMs and TTL were measured in all 4,345 participants of the ESTHER 8-year follow-up and in case-cohort design in the Tromsø study (cancer cases: n = 941; sub-cohort: n = 1,000). Individual study results were pooled by random effects meta-analysis. D-ROM levels were statistically, significantly, positively associated with lung, colorectal and breast cancer but not with prostate cancer in the meta-analysis. Statistically, significantly, inverse associations were observed for TTL and breast and prostate cancer, whereas borderline, non-significant, inverse associations were observed for lung and colorectal cancer in the meta-analysis. Furthermore, a systematic review of literature reviews was conducted to give an overview of redox signaling pathways that are postulated to be involved in cancer development. This systematic review describes the 20 most mentioned redox-regulation pathways, including reactive oxygen species generating organelles and enzymes, kinases and phosphatases families and transcription factors. Overall, 519 genes were identified from the 20 pathways. Based on the ESTHER study, these genes were further used in a screening to identify CpG sites, of which the DNA methylation levels were associated urinary 8-isoprostane levels. Inverse associations of DNA methylation at cg25365794 (ALOXE3), cg01009697 (NTRK2) and cg08862778 (MTOR) with 8-isoprostane levels were observed in a derivation set (n = 1,000) and validated in two independent subsets of the cohort (n = 548 and n = 741). Multivariate regression models were used to evaluate the associations of DNA methylation at the three CpG sites with lung, colorectal, prostate, breast and overall cancer incidence. DNA methylation at cg25365794 (ALOXE3) was inversely associated with lung and prostate cancer incidence. DNA methylation at cg01009697 (NTRK2) was positively associated with overall and lung cancer incidence. DNA methylation at cg08862778 (MTOR) was inversely associated with breast cancer incidence. Both, the NTRK2 and MTOR protein play important roles in PI3K/Akt signaling, which is a pathway involved in cancer development and cell senescence. The presented results support the hypothesis that oxidative stress plays a role in carcinogenesis. DNA methylation alterations in genes, coding for proteins involved in the PI3K/Akt signaling pathway may provide a mechanistic link between the observed association of oxidative stress biomarkers and the incidences of common cancers. In a further part of the project, serum D-ROM concentrations were measured in 1,045 and 1,101 type 2 diabetes patients from two independent cohort studies from Germany at baseline and repeatedly 3-4 years later in order to identify risk factors for high oxidative stress. The meta-analysis of the longitudinal analysis revealed that old age, female sex, obesity, smoking, physical inactivity, high alcohol consumption, ≥ 5 years since diabetes diagnosis and c-reactive protein levels between 3 and 10 mg/L were statistically significantly associated with D-ROM levels measured 3-4 years later. These results support suggestions that a better management of the modifiable risk factors obesity, smoking, physical inactivity and high alcohol consumption may help to maintain redox balance in diabetes patients. Thus, it appears very likely that in part the protection from cancer by following recommendations for a healthy life-style can be ascribed to a maintenance of redox balance as the mechanism of action.
Publications
- Reduction-oxidation pathways involved in cancer development: a systematic review of literature reviews. Oncotarget. 2017; 8:51888-51906
Gao X, Schöttker B
(See online at https://doi.org/10.18632/oncotarget.17128) - Urinary 8-isoprostane levels and occurrence of lung, colorectal, prostate, breast and overall cancer: Results from a large, population-based cohort study with 14 years of follow-up. Free Radic Biol Med. 2018;123:20-26
Gào X, Brenner H, Holleczek B, Cuk K, Zhang Y, Anusruti A, Xuan Y, Xu Y, Schöttker B
(See online at https://doi.org/10.1016/j.freeradbiomed.2018.05.065) - Association of serum markers of oxidative stress with incident major cardiovascular events, cancer incidence and all-cause mortality in type 2 diabetes patients: Pooled results from two cohort studies. Diabetes Care 2019;42(8):1436- 1445
Xuan Y, Gào X, Anusruti A, Holleczek B, Jansen HJM, Muhlack DC, Brenner H, Schöttker B
(See online at https://doi.org/10.2337/dc19-0292) - Pre-diagnostic derivatives of reactive oxygen metabolites and the occurrence of lung, colorectal, breast and prostate cancer: An individual participant data meta-analysis of two large population-based studies. Int J Cancer. 2019;145(1):49-57
Gào X, Wilsgaard T, Jansen EHJM, Holleczek B, Zhang Y, Xuan Y, Anusruti A, Brenner H, Schöttker B
(See online at https://doi.org/10.1002/ijc.32073) - The associations of DNA methylation alterations in oxidative stress-related genes with cancer incidence and mortality outcomes: A population-based cohort study. Clin Epigenetics 2019;11(1):14
Gào X, Zhang Y, Burwinkel B, Xuan Y, Holleczek B, Brenner H, Schöttker B
(See online at https://doi.org/10.1186/s13148-018-0604-y) - Factors associated with high oxidative stress in patients with type 2 diabetes: a metaanalysis of two cohort studies. BMJ Open Diabetes Res Care. 2020;8(1)
Anusruti A, Xuan Y, Gào X, Jansen EHJM, Laetsch DC, Brenner H, Schöttker B
(See online at https://doi.org/10.1136/bmjdrc-2019-000933) - Longitudinal associations of body mass index, waist circumference and waist to hip ratio with biomarkers of oxidative stress in older adults: Results of a large cohort study. Obesity Facts. 2020;13(1):66-76
Anusruti A, Jansen EHJM, Gào X, Xuan X, Brenner H, Schöttker B
(See online at https://doi.org/10.1159/000504711) - Serum total thiol levels and the risk of lung, colorectal, breast and prostate cancer: A prospective case-cohort study. Int J Cancer 2020;146(5):1261-1267
Gào X, Wilsgaard T, Jansen EHJM, Xuan Y, Anusruti A, Brenner H, Schöttker B
(See online at https://doi.org/10.1002/ijc.32428)
