The microRNAs (miRNAs) are small, non-coding RNA molecules of around 22 nucleotides found in animals, plants and some viruses. They have a role in RNA silencing and post-transcriptional regulation of gene expression, modulate almost all biological processes and are essential for maintaining cellular homoeostasis. Dysregulation of miRNA expression has been associated with aberrant gene expression, leading to a wide range of pathological conditions.
Encoded by eukaryotic nuclear DNA in animals and by viral DNA in viruses that have a genome based on DNA, miRNAs function as a result of base-pairing with complementary sequences on messenger RNA (mRNA) strands. This results in ‘silencing’ of the mRNA molecules by cleavage of the mRNA strand, destabilisation through shortening of its poly(A) tail, or less-efficient translation of the mRNA into proteins, or a combination thereof.
MiRNAs resemble small interfering RNAs (siRNAs), but differ in that they are derived from regions of RNA transcripts that fold back on themselves to form short ‘hairpins’. It is thought that the human genome encodes more than 1000 miRNAs, and that they are abundant in many cell types, targeting some 60% of the genes of humans and other mammals.
The ubiquity of miRNA occurrence is reflected in the current literature, which reports a wide range of potential biomarker applications for this highly conserved molecule. These are exemplified by work in areas such as cardiology, respiratory medicine and transplantation.[Citation1–4] However, bearing in mind the potential for base-pair mismatching between mRNAs and miRNAs, various roles as biomarkers in cancer hold considerable promise, as demonstrated, for example, in tumours of the liver,[Citation5] cervix [Citation6] and prostate.[Citation7]
The focus on miRNAs and cancer continues in this issue of BJBS, with work reported on the role of miRNA-124 in pancreatic adenocarcinoma,[Citation8] miRNA-21 in osteosarcoma,[Citation9] and miRNA-146a in gastric cancer.[Citation10] Clearly, this highly conserved molecule may facilitate diagnosis and better treatment for patients with cancer and in a wide range of other disparate medical conditions.
Editor, The Biomedical Scientist
References
- Wang H, Chen F, Tong J, et al. Circulating microRNAs as novel biomarkers for dilated cardiomyopathy. Cardiol J. 2016. Epub. Available from: 10.5603/CJ.a2016.0097
- Alipoor SD, Adcock IM, Garssen J, et al. The roles of miRNAs as potential biomarkers in lung diseases. Eur J Pharmacol. 2016;791:395–404.10.1016/j.ejphar.2016.09.015
- Zheng ML, Zhou NK, Luo CH. MiRNA-155 and miRNA-132 as potential diagnostic biomarkers for pulmonary tuberculosis: a preliminary study. Microb Pathog. 2016;100:78–83.10.1016/j.micpath.2016.09.005
- van de Vrie M, Deegens JK, Eikmans M, et al. Urinary microRNA as biomarker in renal transplantation. Am J Transplant. 2016. Epub. Available from: 10.1111/ajt.14082
- Chen Y, Wang X, Cheng J, et al. MicroRNA-20a-5p targets RUNX3 to regulate proliferation and migration of human hepatocellular cancer cells. Oncol Rep. 2016. Epub. Available from: 10.3892/or.2016.5144
- Wu T, Chen X, Peng R, et al. Let-7a suppresses cell proliferation via the TGF-β/SMAD signaling pathway in cervical cancer. Oncol Rep. 2016. Epub. Available from: 10.3892/or.2016.5160
- Zhang W, Liu J, Qiu J, et al. MicroRNA-382 inhibits prostate cancer cell proliferation and metastasis through targeting COUP-TFII. Oncol Rep. 2016. Epub. Available from: 10.3892/or.2016.5141
- Dong Z. miRNA-124 in pancreatic adenocarcinoma. this issue.
- Ren X. miRNA-21 in osteosarcomax. this issue.
- Yadegari Z. miRNA-146a in gastric cancer. this issue.