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Like snakes, tumor cells shed their skin. Cancer isn’t a static disease, but one that accumulates transformations throughout its development to evade the body’s natural defenses, adapting to new environmental circumstances, protecting itself against chemotherapy and radiotherapy, and progressing to invade neighboring organs, finally leading to metastasis.

Little was previously known about the mechanisms involved in the processes through which tumors change. There is a particularly intriguing mechanism through which a tumor that initially existed in a solid state, attached to the cells themselves (epithelial), becomes a more flexible, liquid mass detached from neighboring tissue (mesenchymal).

The team led by Dr. Manel Esteller, director of the Epigenetics and Cancer Biology Program at the Bellvitge Biomedical Research Institute (IDIBELL), professor of genetics at the University of Barcelona and ICREA researcher, has identified a mechanism that explains this change. Tumors that shed their skin do so because they turn off molecular switches called microRNAs, which are responsible for maintaining the epithelial aspects of cells. These findings were published this week in the digital edition of the international scientific journal Oncogene, from the Nature group.

“The study discovered that some microRNAs, a group called microRNA-200S, undergo a chemical inactivation and inhibit their expression. When these cellular appearance drivers are not present, tumor cells change, stretch, stop their inhibition and thus the tumor progresses”, explains Dr. Esteller, “and the results from research show that this is a very dynamic process.”

The change occurs from the time the tumor appears through metastasis, however if we change the environmental circumstances that influence these cells, the progress reverses.

The study was carried out mainly on breast and colon tumors. In addition to allowing scientists to better understand the disease, the results are important because they allow them to predict that external intervention in the process is possible. In this sense, drug treatments could reverse the process and move from a more highly evolved form of the tumor to a more primitive one, which would be associated with slower progression of the disease.


V. Davalos, C. Moutinho, A. Villanueva, R. Boque, P. Silva, F. Carneiro and M. Esteller. Dynamic epigenetic regulation of the micro RNA-200 family mediates epithelial and mesenchymal transitions in human tumorigenesis. Oncogene, 29 August 2011. doi: 10.1038/onc.2011.383.

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