Non-coding RNAs (ncRNAs), for example microRNAs (miRNAs), are frequently dysregulated in cancer and other diseases, and have shown great potential as tissue-based markers for cancer classification and prognostication. ncRNAs are present in membrane-bound vesicles, such as exosomes, in extracellular human body fluids. Circulating miRNAs are also present in human plasma and serum and cofractionate with the Argonaute2 (Ago2) protein and high-density lipoprotein (HDL). Since miRNAs and other ncRNAs circulate in the bloodstream in highly stable forms, they may be used as blood-based biomarkers for cancer and other diseases. A knowledge base of non-invasive biomarkers is a fundamental tool for biomedical research in this field.
In 2012, miRandola was developed as the first database of circulating extracellular miRNAs (Russo et al., 2012). miRandola is a comprehensive, manually curated collection and classification of circulating extracellular miRNAs. We recently updated miRandola with 271 papers, 2695 entries, 673 miRNAs and 12 long non-coding RNAs. The future direction of the database is to be a resource for all potential non-invasive circulating nucleic acid biomarkers.
miRandola is the first online resource which gathers all the available data on circulating RNAs into one environment (see Figure). It represents a useful reference tool for anyone investigating the role of extracellular RNAs as biomarkers, as well as their physiological function and their involvement in pathologies.
The database is constantly updated as soon as new data is available, and the online submission system is a crucial feature which helps to ensure that the system is always up-to-date. We are working on a second version of the database to increase the amount of data and to improve usability. miRandola is available online at http://mirandola.iit.cnr.it/.