Environmental and Molecular Mutagenesis (EMM) Editor's Choice - July 2013
The Editor's Choice for July is "Aberrant DNA Methylation of miR-219 Promoter in Long-Term Night Shiftworkers” by Fengqin Shi, Xinyi Chen, Alan Fu, Johnni Hansen, Richard Stevens, Anne Tjonneland, Ulla B. Vogel, Tongzhang Zheng, and Yong Zhu.
Shiftwork has been associated with the development of cancer, including breast cancer. Such associations may be due to altered expression of circadian genes (genes regulated by normal day/night cycle), which in turn cause abnormal regulation of genes with cancer-related functions. Fengqin Shi and colleagues chose a unique approach for investigating the link between circadian genes and cancer. They sought evidence that epigenetic regulation, specifically promoter methylation of microRNAs (miRNAs), was altered by shiftwork, and that the altered microRNA expression modulated the expression of genes with cancer-related functions. Dr. Shi and colleagues examined the methylation status of 255 CpG sites in the promoters for 110 different microRNAs in both day workers and long-term nightshift workers. They found differences in the methylation stateof 50 different CpG methylation sites in 29 different miRNAs between day and nightshift workers. To confirm that such changes could impact cancer-related cell functions, one of the hypermethylated miRNAs (miR-219) was overexpressed in a breast cancer cell line and the resulting changes in gene expression were characterized. Dr. Shi and colleagues observed that multiple gene with immune-related functions that can impact cellular proliferation and apoptosis were induced by the overexpression of miR219. From their results, Dr. Shi and colleagues conclude methylation of miR219 due to long-term night shiftwork may result in downregulation of immunomediated antitumor activity, which could result in an increased risk of breast cancer. Environ. Mol. Mutagen. 54:406–413, 2013. © 2013 Wiley Periodicals, Inc.