Breast cancer risk and epigenetic effects of the rotating night shift work and lifestyle.

Breast cancer risk and epigenetic effects of the rotating night shift work and lifestyle

Breast cancer is the most common type of cancer, accounting for 22.8 % of total number of the incident cancer cases worldwide (Globocan, 2008). Over the last years, the influence of night shift work on cancer risk has drawn much attention from researchers worldwide.

Despite a growing body of evidence that suggest a link between night shift work and breast cancer risk, the mechanisms underlying this association remain to be elucidated.
Through a common initiative, Polish  and Norwegian  researchers will test mechanistic hypotheses addressing a number of key issues potentially relevant for breast carcinogenesis in women with night shift exposure.

The primary focus of the proposal will be to investigate the association between night shift work and breast cancer risk and to study epigenetic changes related to night shift work. A major epigenetic mechanism that may affect gene expression in disease is changes in the levels of 5-methylcytosine (5meC) in the promoter regions of genes. Global methylation and promoter methylation status will be investigates for core circadian genes, melatonin receptor genes, estrogen and progesterone receptor genes, cell cycle regulatory genes, and tumour suppressor genes.

Data and biological samples from two epidemiological studies will be used. The first is a nested case-control study within a Norwegian cohort of female nurses. The second is a cross-sectional study of nurses and midwives in Poland. In the Norwegian study, methylation levels in DNA from breast cancer cases and controls will be compared. In both the Norwegian and Polish studies, the effects of night shift work on epigenetic changes will be analyzed. Associations between lifestyle factors: diet, alcohol consumption, smoking physical activity and sleep deprivation and methylation of  tumour suppressor genes will be investigated. These exploratory studies have a potential of elucidating novel mechanisms by which night shift work may influence breast cancer. Because some epigenetic events are preventable, the results obtained from this study could lead to new strategies for cancer prevention.


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