THE LONG AND WINDING ROAD OF MICRORNA PROFILING FROM BENCH TO BEDSIDE

MicroRNAs (miRNAs) are short non-coding RNAs that control the expression of the majority of protein-coding genes within a cell. Their dysregulation is both cause and indication of a variety of diseases, including cancer. Specific patterns of miRNAs' expression enable researchers to classify cancer subtypes and their differentiation grade. As a consequence, miRNAs are considered promising cancer biomarkers to be adopted in the clinical routine. Recent technical advancements have allowed for the profiling of thousands of miRNAs in parallel, and in large sets of samples. However, the information gained from these analyses has been insufficient to build reliable diagnostic and prognostic workflows in the clinical laboratory. Here we describe some of the recent protocols used to profile miRNA expressions and highlight both advantages and limitations associated with them. Finally, we propose that, besides the measurement of total expression of miRNAs, assessment of other parameters-such as miRNAs' editing patterns and subcellular localization-may be integrated to make miRNAs more powerful cancer biomarkers.