Circulating
microRNAs (
miRNAs) are receiving attention as potential
biomarkers of various diseases, including
cancers,
chronic obstructive pulmonary disease, and
cardiovascular disease. However, it is unknown whether the levels of circulating
miRNAs in a healthy subject might vary with external factors in daily life. In this study, we investigated whether cigarette smoking, a habit that has spread throughout the world and is a risk factor for various diseases, affects plasma
miRNA profiles. We determined the profiles of 11 smokers and 7 non-smokers by TaqMan
MicroRNA array analysis. A larger number of
miRNAs were detected in smokers than in non-smokers, and the plasma levels of two-thirds of the detected
miRNAs (43
miRNAs) were significantly higher in smokers than in non-smokers. A principal component analysis of the plasma
miRNA profiles clearly separated smokers and non-smokers. Twenty-four of the
miRNAs were previously reported to be potential
biomarkers of disease, suggesting the possibility that smoking status might interfere with the diagnosis of disease. Interestingly, we found that quitting smoking altered the plasma
miRNA profiles to resemble those of non-smokers. These results suggested that the differences in the plasma
miRNA profiles between smokers and non-smokers could be attributed to cigarette smoking. In addition, we found that an acute exposure of ex-smokers to cigarette
smoke (smoking one cigarette) did not cause a dramatic change in the plasma
miRNA profile. In conclusion, we found that repeated cigarette smoking substantially alters the plasma
miRNA profile, interfering with the diagnosis of disease or signaling potential smoking-related diseases.