MicroRNAs in clinical oncology: at the crossroads between promises and problems

MicroRNAs (miRNAs) are small RNAs that do not code for proteins, but function by controlling protein expression of other genes. miRNAs have been shown to control cell growth, differentiation and apoptosis. Shortly after their discovery, miRNAs have been found to be associated with cancer. Earlier reports have shown that human cancers frequently show a distorted expression profile of miRNAs. In this review, the biogenesis of miRNAs and potential mechanisms of their dysregulation and involvement in cancer pathogenesis are discussed. The current literature on potential applications of miRNAs in the field of clinical oncology from diagnostic to prognostic and predictive applications at the tissue, and more recently, serum levels, is reviewed. The potential therapeutic applications of miRNAs and RNAi in the field of cancer are summarised. Finally, some of the potential challenges that face the transition of miRNAs from a research setting into a clinical application are highlighted, with a future prospective of the incorporation of miRNAs in cancer patient management.