All human cells have a central core where the DNA (our genetic material) is, an aqueous medium (cytoplasm) where the proteins are produced and metabolic processes take place, and a peripheral layer around the cell that gives shape (plasma membrane). There is a continuous traffic of molecules between these three compartments that allows the normal function of the cell.

The recent discovery led by Manel Esteller team, ICREA researcher at Barcelona, shows that this traffic is disrupted in cancer cells. The group of small molecules sequestered by the tumor cell at its core are called microRNAs. They cannot exercise their normal activity to inhibit cancer development.

"The tumours described" says Manel Esteller, "have a mutation in a protein called exportin-5, whose function in a healthy cell is to transport microRNAs from nucleus to cytoplasm. But in these cancers is unable to lead them out of the nucleus, so it loses its protective anti-tumour ability."

"These results have implications for better understanding of the causes of cancer, but also for possible new treatments, because on the one hand we discover a new way altered in cancer that was utterly unknown, and, secondly, there is a new molecular target, which should stimulate the search for new drugs that help improve the transport of molecules from the nucleus." Paper reference
Melo SA, Moutinho C, Ropero S, Calin GA, Rossi S, Spizzo R, Fernandez AF, Davalos V, Villanueva A, Montoya G, Yamamoto H, Schwartz Jr, Esteller M. A Genetic Defect in Exportin-5 Traps Precursor MicroRNAs in the Nucleus of Cancer Cells. Cancer Cell