Article Text

Download PDFPDF

1193 Night-shifts, dna methylation and telomere length: preliminary results from a survey on a sample of italian nurses
  1. M Carugno1,
  2. E Crespi2,
  3. V Bollati1,
  4. L Tarantini1,
  5. L Dioni1,
  6. D Consonni3,
  7. C Maggioni2,
  8. G Costa2,3,
  9. AC Pesatori1,3
  1. 1EPIGET Lab, Dept. Clinical Sciences and Community Health, Università degli Studi di Milano, Milan, Italy
  2. 2Dept. Clinical Sciences and Community Health, Università degli Studi di Milano, Milan, Italy
  3. 3Occupational Medicine Unit, Fondazione IRCCS Ca’ Granda – Ospedale Maggiore Policlinico, Milan, Italy


Introduction IARC defined shift work as probably carcinogenic to humans (Group 2A), after investigations highlighted an increased breast cancer risk in night-shift female workers. The biological mechanisms underlying this association are still unclear. Hence, we evaluated the relationship between night-shift work and molecular alterations potentially related to increased cancer risk, in detail: DNA methylation of the oestrogen receptor gene (ER-Beta) and tumour suppressor genes (BRCA1, p53, p16), global DNA methylation estimated in repeated elements (LINE-1, Alu) and telomere length (TL).

Methods 46 female nurses (age: 35–45 years) who had been working in night-shifts for at least two years (length of service ≥five years) were recruited at the Policlinico Hospital (Milan, Italy) and matched for age, sex and length of service to 51 colleagues not working in night-shifts. Each subject was administered a structured questionnaire and withdrawn a 12 mL blood sample. Linear regression models adjusted for age, BMI, parity, smoking habit and oral contraceptive use were then applied.

Results Working in night-shifts (yes/no) was associated with BRCA1 hypomethylation (β: −0.512, 95% CI: −1.039 to 0.015). When considering also former night-shift workers, the number of years in night-shifts (NYNS) was associated with hypomethylation of BRCA1 (β: −0.084, 95% CI: −0.127 to −0.042), p53 (β: −0.072, 95% CI: −0.133 to −0.011) and LINE-1 (β: −0.043, 95% CI: −0.083 to −0.002). After graphically inspecting the NYNS-TL relationship, we stratified our study population by NYNS <15 vs ≥15 years. Among nurses with NYNS ≥15 years, NYNS was associated with telomere shortening (β: −0.065, 95% CI: −0.122 to −0.008) and hypermethylation of BRCA1, p53 and LINE-1.

Conclusion Our results show epigenetic alterations that might play a role in cellular ageing, genomic instability and carcinogenesis. We are currently extending our study to other molecular targets involved in the cascade of events that might bring from night-shift exposure to cancer.

  • shift work
  • epigenetics
  • cancer

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.