Genome-wide hypomethylation of LINE-1 and Alu retroelements in cell-free DNA of blood is an epigenetic biomarker of human aging

• Main Authors: Lars Erichsen, Agnes Beermann, Marcos J. Arauzo-Bravo, Mohamed Hassan, Mohamed A. Dkhil, Saleh Al-Quraishy, Taghreed A. Hafiz, Johannes C. Fischer, Simeon Santourlidis
• Format: Article
• Language: English
• Published: Elsevier 2018-09-01
• Series: Saudi Journal of Biological Sciences
• Online Access: http://www.sciencedirect.com/science/article/pii/S1319562X18300408

Aging associated DNA hypomethylation of LINE-1 and Alu retroelements may be a crucial determinant of loss of genomic integrity, deterioration and cancer. In peripheral blood LINE-1 hypomethylation has been reported to increase during aging, but other studies did not observe significant changes. We hypothesized that these apparently inconsistent reports might relate to differences between cellular and cell-free DNA. Using the technique of idiolocal normalization of real-time methylation-specific PCR (IDLN-MSP) for genetic imbalanced DNA specimens we obtained evidence that LINE-1 hypomethylation in cell-free DNA, but not cellular DNA from peripheral blood is an epigenetic biomarker for human aging. Furthermore, hypomethylation of cell-free DNA is more extensive in smokers, suggesting that it might be used as a surrogate marker for monitoring the improvement of smoking-induced adverse effects after cancelling smoking. Keywords: Epigenetics, DNA methylation, Cell-free DNA, Retroelements, LINE-1