Effect of Aging and Sex on Circulating MicroRNAs in Humans

Abstract

MicroRNAs (miRNAs) have been reported as potentially being useful biomarkers for various dis-eases including cancer, diabetes mellitus, heart disease, neurological disease and age-related dis-eases. In the present study, we aimed to determine whether the expression levels of circulating miRNAs in serum were changed with aging or sex. Serum samples from seven elderly males (69.86 ± 1.77 years old) and females (72.43 ± 1.49 years old), and six young males (26.17 ± 0.83 years old) and females (23.17 ± 1.52 years old) were obtained from the subject's forearm at rest. The expres-sion levels of circulating miR-146a and miR-20a in serum were determined by real-time TaqMan PCR. There were no differences in the expression levels of miR-146a between all groups. There was a significant interaction in this main effect where miR-20a levels were significantly lower in elderly male subjects when compared to young male subjects with no difference observed in young or elderly female subjects (p = 0.004 and p = 0.971, respectively). These results suggest that not all the miRNAs in the circulation are influenced by the effect of aging, but only some miRNAs may be selectively changed by the effect of aging.