MicroRNAs: a new paradigm on molecular urological oncology.

MicroRNAs (miRNA) are a class of naturally occurring, small, noncoding RNAs that function as specific repressors of protein-encoding genes, being pivotal regulators of development and cellular homeostasis. They have been functionally classified as proto-oncogenes or tumor suppressors and are aberrantly expressed in different cancer types. Deregulation of these so-called "cancerous" miRNAs can figure prominently in tumor initiation and progression. The Human miRNA profile is under development, and it is of concern that there is so little agreement on the miRNAs found in each of the studies. Bioinformatics progress and efficient delivery are essential to overcome barriers to miRNA use in clinical practice.