Jacobs Journal of Cancer Science and Research

Circulating microRNAs as Cancer Early Diagnostic Biomarkers-Promises and Concerns

*Chengfeng Yang
Department Of Physiology, Michigan State University, United States

*Corresponding Author:
Chengfeng Yang
Department Of Physiology, Michigan State University, United States
Email:yangcf@msu.edu

Published on: 2014-07-24

Abstract

MicroRNAs (miRNAs) are a large family of small non-coding RNAs that negatively regulate protein-coding gene expression post-transcriptionally. Since the discovery of first miRNA in 1993 and the first reporting of the presence of circulating miRNA in 2008, numerous studies have demonstrated the potential involvement of miRNAs in almost all aspects of cancer. In aiming to identify minimally invasive cancer early diagnostic biomarkers, a large number of studies have shown differential expression profiles or signatures of circulating miRNAs between healthy control populations and various cancer patients. Unfortunately, the reported circulating miRNA signatures that have been claimed to be able to separate healthy controls and cancer patients are often sporadic and lack consensus among different studies. Apparently, further studies are needed to identify and overcome potential confounding factors that contribute to this poor reproducibility of reported circulating miRNA signatures before the findings could be translated into clinical practice. In this short review, we will briefly discuss the promises and concerns of circulating miRNAs as cancer early diagnostic biomarkers.

Keywords

Noncoding RNA; microRNA; Circulating microRNA; Cancer Diagnostic Biomarker

Introduction

The first microRNA (miRNA), lin-4, was discovered in 1993 and referred to as a “small regulatory RNA”. The term “miRNA” was first introduced in 2001 when three groups simultaneously reported the findings of a big number of miRNAs in the same issue of Science. Since then, many studies have shown that miRNAs are a large family of small non-coding RNAs (~22 nucleotide long) that negatively regulate protein-coding gene expression post-transcriptionally by interacting with messenger RNAs (mRNAs). The interaction of miRNAs with mRNAs occurs through imperfect base pairing between the miRNA and mRNA 3'-untranslated region (3'UTR), principally involving the seed region of 6-8 nucleotides at the 5' end of the miRNA, and causing mRNA degradation or translation inhibition. According to the latest version (June 2014) of miRBase, Release 21 of the database contains 28645 precursor miRNAs and 35828 mature miRNAs in 223 species. This recently updated miRNA database listed 1881 human precursors and 2588 human mature miRNAs. Many studies have shown that the expression levels of miRNAs are often altered in many human diseases and extensive studies in this field have focused on cancer.