Dysregulation of
microRNAs (
miRNAs), particularly their downregulation, has been widely shown to be associated with the development of
lung cancer. Downregulation of
miRNAs leads to the overactivation of their oncogene targets, while upregulation of some
miRNAs leads to inhibition of important
tumor suppressors. Research has implicated cigarette
smoke in
miRNA dysregulation, leading to
carcinogenesis. Cigarette
smoke may lead to genetic or epigenetic damage to
miRNAs, many of which map to fragile sites and some of which contain single nucleotide polymorphisms. Cigarette
smoke may also cause dysregulation by affecting regulatory mechanisms controlling
miRNA expression. Researchers have shown a correlation between
smoke-exposure-induced dysregulation of
miRNAs and age. Furthermore, dysregulation seems to be associated with intensity and duration of
smoke exposure and duration of cessation. Longer exposure at a threshold level is needed for irreversibility of changes in expression. Better understanding of
miRNA dysregulation may allow for improved biomonitoring and treatment regimens for
lung cancer.