MicroRNAs (miRNAs) comprise a class of small endogenous non-coding RNA molecules that play critical roles in modulating numerous biological pathways by regulating gene expression. High throughput and expression profile studies have shown that miRNAs are commonly dysregulated in human cancer. The study of the mechanisms of action of miRNAs has uncovered an entirely new repertoire of potential biomarkers and generegulated pathways. MiRNAs may function as oncogenes or tumour suppressor genes and are characterised by unique properties such as stability, tissue specificity, ease of detection and manipulation. Additionally, miRNAs are differentially expressed in the blood of cancer patients versus healthy donors, providing a rationale for the detection of miRNAs as diagnostic and prognostic circulating biomarkers. Recent studies have shown that specific expression patterns of miRNAs could be used as potential predictors of response to treatments in clinical trials. Finally, manipulation of miRNA expression in cancer could be used for future molecular therapies.
