microRNA in cancer: An overview

The extent of the dogmatic shift in molecular biology caused by the discovery of noncoding RNAs was initially difficult to assess, as the rather restrictive implications and orthologues of the first observed microRNA (miRNA) were yet to be explored in humans, even less so in pathological contexts such as cancer. Therefore, the mapping of two microRNA to the frequently deleted region in chronic lymphocytic leukemia patients came as a great surprise, as it gave a new “purpose” to previously disregarded regions of the human genome. The extension of the noncoding genome paradigm came as more roles were attributed to these transcripts in different pathological conditions, laying the foundations for a completely new area of research in oncology. As such, the aim of this overview is not only to mention the groundbreaking studies that have shaped cancer miRNA research, but also to emphasize their influence on cancer research to this day. Additionally, we will approach the crucial terms in miRNA biology with a steady introduction into the more mechanistic and cancer-specific processes, which will be detailed in the later chapters of this book along with the evolution of investigation methods and their future perspectives in diagnostics and therapy.