MicroRNAs and Their Role in Cancer

Manuela Ferracin, University of Ferrara, Ferrara, Italy
Massimo Negrini, University of Ferrara, Ferrara, Italy

Published online: April 2012

DOI: 10.1002/9780470015902.a0021434

Microribonucleic acids (miRNAs) are short, noncoding RNAs that act as post‐transcription regulators and are able to modulate the expression of hundreds of target genes. In the past few years, they gained a very important role in oncology. Indeed, many of them can be now considered tumour suppressor genes or oncogenes. In cancer, they appeared to have a dysregulated expression due to genetic aberrations, altered methylation or irregular processing that finally lead to an altered modulation of their target genes.

Each cancer type displayed specific alterations of specific miRNAs, and their exceptional stability confer to miRNAs a strong potential as cancer therapeutics. Finally, miRNAs are stable and detectable as circulating molecules in blood of cancer patients. For this reason they are going to become useful biomarkers in cancer diagnostics.

Key Concepts:

  • In the last few years, miRNAs have produced a micro‐revolution in cancer research because of their action as oncogenes or tumour suppressor genes.
  • miRNA expression profiling may be used for cancer classification and for the identification of cancer subtypes.
  • A promising role of miRNA in prognosis stratification has been proposed.
  • Several studies indicated miRNAs as predictors of drug response.
  • miRNA polymorphisms may modify innate genetic susceptibility to cancer: SNPs in miRNAs and their gene targets may alter cancer susceptibility.
  • miRNAs as cancer biomarkers detected in plasma or serum of patients seem to be very promising in terms of efficacy and specificity.
  • miRNA may represent important therapeutic targets and can be effectively targeted in vivo.

Keywords: microRNA; cancer; oncogene; tumour suppressor gene; therapy; prognosis; biomarker

Figure 1. (a) Tumour suppressor microRNAs. Mechanisms that reduce miRNA expression in cancer cells finally lead to reduced levels of miRNAs in cytoplasm and impair their action on target genes through 3′‐UTR binding. Oncogenic proteins that are regulated by these miRNAs are therefore translated at higher levels than in normal cells. (b) Oncogenic microRNAs. An increased production of microRNAs in cancer cells determines a more powerful inhibition of target genes. If the target is a tumour suppressor gene, its expression is reduced and the protein cannot exert its protective action.
Figure 2. Targets of microRNAs in cancer cells. Deregulation of miRNAs in cancer cells may occur by genetic or epigenetic changes, by anomalous transcription factors expression and by abnormal responsiveness to various stimuli. Increased or impaired miRNA expression may ultimately affect the expression of target genes. As a result, cells may not differentiate or undergo apoptosis, or they may increase their proliferation rate, motility and invasiveness, properties that represent hallmarks of cancer.
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Related Sub-Topics:

Cancer Genetics | RNA Structure and Function
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Article Title: MicroRNAs and Their Role in Cancer
 
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Ferracin, Manuela, and Negrini, Massimo(Apr 2012) MicroRNAs and Their Role in Cancer. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0021434]