Circulating MicroRNAs in Serum and Other Body Fluids as Diagnostic Biomarkers in Cancer

microRNAs are small non-coding RNAs which negatively regulate several the expression of target genes at the post-transcriptional level. These non-coding RNAs are involved in different mechanisms including proliferation، differentiation، metabolism، aging، and apoptosis. Deregulation of miRNAs expression is linked with various diseases such as cancer. Human serum and other body fluids are a rich source of biomarkers that can be used in clinical diagnosis. Recently، it has been reported that there are enough stable circulating miRNAs in the serum and body fluids. Therefore، the profile of circulating miRNAs is considered in many studies and is a promising perspective as non-invasive biomarkers. In this review، we will focus on the distribution of circulating miRNAs and their physiological and pathological functions. Finally، some molecular techniques will be presented that are related to detection and analysis of circulating miRNAs as biomarkers.