NOX/DUOX Gene Family Methylation in the Association Between Long-Term Particulate Matter Exposure and Lung Cancer
BUI L. 1, JOO M. 1, HONG K. 1, SHIN M. 1, LIM Y. 2, HONG Y. 3, KIM J. 4, JEE S. 5, KIM S. 1, HUYN J. 6,7, CHOI Y. 1,8,9
1 Department of Public Health and AI, National Cancer Center Graduate School of Cancer Science and Policy, Goyang-si Gyeonggi-do, Korea (Republic of); 2 Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark; 3 Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Korea (Republic of); 4 Department of Cancer Biomedical Science, National Cancer Center Graduate School of Cancer Science and Policy, Goyang, Korea (Republic of); 5 Graduate School of Transdisciplinary Health Sciences, Yonsei University, Seoul, Korea (Republic of); 6 Department of Biochemistry, College of Medicine, Jeju National University, Jeju, Korea (Republic of); 7 Jeju Research Center for Natural Medicine, Jeju National University, Jeju, Korea (Republic of); 8 National Cancer Control Institute, National Cancer Center, Goyang, Korea (Republic of); 9 Center for Cancer Prevention and Detection, National Cancer Center, GoYang, Korea (Republic of)
Background: Lung cancer remains the leading cause of cancer mortality worldwide. DNA methylation (DNAm) can mediate environmental effects on oxidative stress–related pathways, including those regulated by the NOX/DUOX gene family. However, the epigenetic impact of long-term PM?? exposure on NOX/DUOX genes and lung cancer risk remains unclear. Objective: To examine the associations between long-term PM?? exposure and DNA methylation changes in NOX/DUOXgenes, and to evaluate whether these epigenetic alterations are associated with lung cancer risk. Methods: We conducted a nested case–control study using two independent Korean cohorts. Discovery analyses were performed in the Korean Cancer Prevention Study-II (KCPS-II), followed by validation in an independent cohort - the National Cancer Center (NCC) Health Examinees’ cohort. Genome-wide DNAm was measured in pre-diagnostic peripheral blood using the Infinium HumanMethylationEPIC array. Long-term residential PM?? exposure (2001–2019) was estimated using a universal kriging model. Targeted analyses focused on CpG sites within DUOX1, DUOX2, and NOX3–5. Associations between PM?? exposure and DNAm were assessed using linear regression models adjusted for age, sex, and smoking status, with effect estimates expressed as interquartile-range changes in methylation β-values per 10 μg/m³ increase in PM?? across multiple exposure windows (3–13 years before diagnosis and period-specific averages). Associations between DNAm and lung cancer risk were evaluated using conditional logistic regression. Results: In the discovery cohort (KCPS-II, n=316), long-term PM?? exposure was associated with DNA methylation changes in NOX/DUOX genes, with evidence of temporally stable effects. In particular, methylation at NOX3,cg24472970 was inversely associated with PM?? across exposure windows from 4 to 13 years (min β = -0.17; P < 0.05).In the independent validation cohort (NCC, n=110), consistent inverse associations were observed for DUOX1 and NOX4. Methylation at DUOX1 cg20442586 decreased with increasing PM?? across 3–13-year windows (β = -0.36 to -0.42; P ≤ 0.02), while promoter CpG sites within NOX4, most notably cg08725840 showed robust inverse associations across nearly all exposure windows (β = -0.39 to -0.51; P ≤ 0.01). Sex-stratified analyses further indicated a female-specific epigenetic response. PM?? exposure during 2011–2019 was inversely associated with methylation at DUOX1 cg23166740 among women in both cohorts (KCPS-II (n=99): β = -0.49 to -0.68, P ≤ 0.049; NCC (n=23): β = -1.56 to -1.71, P ≤ 0.017).
Furthermore, distinct CpG sites within the NOX5 gene were associated with lung cancer risk in the discovery and validation cohorts. In the KCPS-II cohort, higher methylation at cg13323256 was associated with a reduced risk of lung cancer (OR per IQR = 0.65). In contrast, in the NCC cohort, increased methylation at two different NOX5 CpG sites, cg12945769 and cg22952917, was associated with a higher risk of lung cancer (ORs per IQR = 1.88–2.09). Conclusions: Long-term PM?? exposure is associated with temporally stable DNAm changes in NOX/DUOX genes across independent cohorts. Although CpG-level replication for lung cancer risk was limited, consistent involvement of oxidative stress-related genes, particularly NOX5, supports an epigenetic pathway linking air pollution exposure to lung carcinogenesis.