A knowledge base for the discovery of function, diagnostic potential and drug effects on cellular and extracellular miRNAs

Background: MicroRNAs (miRNAs) are small noncoding RNAs that play an important role in the regulation ofvarious biological processes through their interaction with cellular mRNAs. A significant amount of miRNAs hasbeen found in extracellular human body fluids (e.g. plasma and serum) and some circulating miRNAs in the bloodhave been successfully revealed as biomarkers for diseases including cardiovascular diseases and cancer. ReleasedmiRNAs do not necessarily reflect the abundance of miRNAs in the cell of origin. It is claimed that release ofmiRNAs from cells into blood and ductal fluids is selective and that the selection of released miRNAs may correlatewith malignancy. Moreover, miRNAs play a significant role in pharmacogenomics by down-regulating genes thatare important for drug function. In particular, the use of drugs should be taken into consideration while analyzingplasma miRNA levels as drug treatment. This may impair their employment as biomarkers.Description: We enriched our manually curated extracellular/circulating microRNAs database, miRandola, byproviding (i) a systematic comparison of expression profiles of cellular and extracellular miRNAs, (ii) a miRNA targetsenrichment analysis procedure, (iii) information on drugs and their effect on miRNA expression, obtained byapplying a natural language processing algorithm to abstracts obtained from PubMed.Conclusions: This allows users to improve the knowledge about the function, diagnostic potential, and the drugeffects on cellular and circulating miRNAs.