OncomicroARNs and their future pharmacological applications

Since the discovery of the central dogma of Molecular Biology, ribonucleic acid (RNA) was postulated as a messenger molecule, which transmitted the information of protein synthesis from DNA, in the cell nucleus, to the cytoplasm. However, research work has shown that RNA also performs functions beyond that of acting as a messenger. Thus, today it is known that there is a large number of non-protein coding RNA molecules that play a fundamental role in the cell. MicroRNAs (miRNAs) belong to this non-protein-coding RNA and their study has revolutionized our knowledge about the functionality of RNAs. MicroRNAs are gene expression regulatory molecules that help determine when or where genes are translated into protein. As their name indicates, these molecules are composed of nucleic acids (RNA) and not protein, in contrast to previously known regulators of gene expression. Due to their small size (human genes are encoded by thousands of nucleotides and microRNAs by only twenty) and their peculiar nature, microRNAs were discovered in the human genome once it was sequenced. MicroRNAs play a fundamental role in establishing cell identity. Components of the microRNA synthesis machinery, or microRNAs per se, have been associated with human pathologies. MicroRNAs have been found to play an important role in many cellular processes that are altered in cancer, such as differentiation, proliferation, and apoptosis. Thus, genes that code for microRNAs have been found in chromosomal regions frequently gained or lost in cancer. Some microRNAs have altered expression levels in cancer and have demonstrated their ability to affect cell transformation, carcinogenesis, and metastasis by acting as oncogenes or tumor suppressors. These microRNAs that are involved in tumor development have been called onco-microRNAs, and their name gives the title to this work. We are only at the beginning of understanding the functional implications of the gain or loss of a particular microRNA in cancer, and early pharmacological applications for cancer treatment are still being tested. Despite everything, this field is providing a series of promising medical applications in the diagnosis, prognosis and treatment of cancer that could provide new tools for the medicine of the future.