Night Shift Work, DNA Methylation and Telomere Length: An Investigation on Hospital Female Nurses

• Published in: International journal of environmental research and public health Vol. 16; no. 13; p. 2292
• Main Authors: Carugno, Michele, Maggioni, Cristina, Crespi, Eleonora, Bonzini, Matteo, Cuocina, Simone, Dioni, Laura, Tarantini, Letizia, Consonni, Dario, Ferrari, Luca, Pesatori, Angela Cecilia
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 28.06.2019; MDPI
• Subjects: Adult; Age; Biological properties; Biological samples; Breast cancer; Cell growth; Circadian rhythms; Contraceptives; Copy number; Demographics; Deoxyribonucleic acid; Disruption; DNA; DNA Methylation; Epigenetics; Epithelial cells; Estrogens; Female; Genes; Genetic testing; Genomic Instability; Hospitals; Humans; Immunosuppressive agents; Immunosurveillance; Melatonin; Menstrual cycle; Middle Aged; Night shifts; Nurses; Nursing Staff, Hospital; Parity; Pregnancy; Regression analysis; Schedules; Shift work; Shift Work Schedule; Sleep; Sleep deprivation; Smoking; Studies; Telomere; Tumors; Variables; Working conditions; Young Adult; United States > US; DNA methylation; night shift work; breast cancer; female nurses; telomere length
• ISSN: 1660-4601; 1661-7827; 1660-4601
• DOI: 10.3390/ijerph16132292

Increased breast cancer risk has been reported in some night shift (NS) workers but underlying biological mechanisms are still unclear. We assessed the association between NS work and DNA methylation of tumor suppressor ( , , , ) and estrogen receptor ( , ) genes, methylation of repetitive elements ( , ), and telomere length (TL). Forty six female nurses employed in NS for at least two years were matched by age (30-45 years) and length of service (≥1 year) with 51 female colleagues not working in NS. Each subject underwent a semi-structured interview and gave a blood sample. We applied linear regression and spline models adjusted for age, BMI, smoking habit, oral contraceptive use, parity and marital status/age at marriage. Currently working in NS was associated with hypomethylation (β: -1.85 (95%CI: -3.03; -0.67), = 0.003). In current and former NS workers we observed (-0.93 (-1.73; -0.12), = 0.03) and (-1.14 (-1.71; -0.58), <0.001) hypomethylation. We found an increase between TL and number of years in NS in subjects employed in NS <12 years (0.06 (0.03; 0.09), <0.001), while a decrease if employed in NS ≥12 years (-0.07 -0.10; -0.04), <0.001). Our findings show NS-associated markers potentially involved in cellular aging, genomic instability, and cancer development.