Department of Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, 8 Teresy St., Lodz, Poland.
Scand J Work Environ Health. 2013 Mar 1;39(2):187-94. doi: 10.5271/sjweh.3303. Epub 2012 May 2.
It has been hypothesized that the underlying mechanism of elevated breast cancer risk among long-term, night-working women involves circadian genes expression alteration caused by exposure to light at night and/or irregular work hours. The aim of the present study was to determine the effect of rotating night shift work on expression of selected core circadian genes.
The cross-sectional study was conducted on 184 matched nurses and midwives, who currently work either day or rotating night shifts, to determine the effect of irregular work at night on circadian gene expression in peripheral blood leukocytes. Transcript levels of BMAL1, CLOCK, CRY1, CRY2, PER1, PER2, and PER3 were determined by means of quantitative real-time polymerase chain reaction (PCR).
After adjusting for hour of blood collection, there were no statistically significant changes of investigated circadian genes among nurses and midwives currently working rotating night shifts compared to nurses working day shifts. The highest expression of PER1 messenger ribonucleic acid (mRNA) was observed for women currently working shifts who had worked >15 years in rotating night shift work. PER1 gene expression was associated with the lifetime duration of rotating night shift work among women currently working night shifts (P=0.04). PER1 and PER3 transcript levels in blood leukocytes were significantly down-regulated in the later versus early hours of the morning between 06.00-10.00 hours (β-coefficient -0.226, P=0.001 and β-coefficient -0.181, P<0.0001, respectively).
These results suggest that current rotating night shift work does not affect circadian gene expression in human circulating leukocytes. In analysis of the peripheral clock in human studies, the hour of blood collection should be precisely specified.
据推测，长期上夜班的女性乳腺癌风险升高的潜在机制涉及到由于夜间暴露于光和/或不规则工作时间而导致的生物钟基因表达改变。本研究旨在确定轮班夜班工作对选定核心生物钟基因表达的影响。
本横断面研究对 184 名目前从事白班或轮班夜班工作的护士和助产士进行了研究，以确定夜间不规则工作对周围血白细胞中生物钟基因表达的影响。通过定量实时聚合酶链反应（PCR）测定 BMAL1、CLOCK、CRY1、CRY2、PER1、PER2 和 PER3 的转录水平。
在校正采血时间后，与从事白班工作的护士相比，目前从事轮班夜班工作的护士和助产士的调查生物钟基因没有统计学上的显著变化。目前从事轮班夜班工作且轮班夜班工作时间>15 年的女性 PER1 信使核糖核酸（mRNA）表达最高。PER1 基因表达与目前从事夜班工作的女性轮班夜班工作的终生持续时间有关（P=0.04）。与凌晨 06.00-10.00 小时相比，血液白细胞中 PER1 和 PER3 转录水平在清晨的后期明显下调（β系数-0.226，P=0.001 和β系数-0.181，P<0.0001）。
这些结果表明，目前的轮班夜班工作不会影响人类循环白细胞中的生物钟基因表达。在人类外周时钟的研究分析中，应精确指定采血时间。
