Metastasis refers to the spread of cancer cells to distant organs in the body. Although metastasis is the major cause of mortality in cancer patients, there are still many unanswered questions at the cellular and molecular level. miRNAs seem to join the pieces of this huge puzzle and may offer the unique potential to understand in a better way the biology of metastasis and resistance mechanisms to established therapies. This editorial focuses on the last advances on the role of microRNAs in the regulation of metastasis as well as in cancer monitoring and therapy.
miRNAs are small molecules (22–25 nt) that play an important role in gene regulation, as they can target multiple ‘genes’ for the ‘fine tuning’ of their expression. The first association between miRNAs and cancer was shown in 2002 by George Calin and Carlo Croce, who, after 7 years of research, revealed that two miRNAs were causally involved in the pathogenesis of chronic lymphocytic leukemia . Today, 12 years after this important finding, a plethora of more than 1800 human miRNAs have been unveiled, and their role as key players in several stages of metastasis has been demonstrated in several studies .