Another Case of Cellular Identity Theft

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Science  30 Nov 2007:
Vol. 318, Issue 5855, pp. 1353
DOI: 10.1126/science.318.5855.1353b

Solid tumors use a variety of crafty mechanisms to optimize their growth, invasion, and metastasis. One unusual mechanism that has attracted much recent interest is a form of cellular identity theft whereby tumor cells morph into a different cell type or induce surrounding normal cells to do so. The best characterized of these phenotypic changes is EMT, or “epithelial-mesenchymal transition,” a process thought to endow tumor epithelial cells with migratory and invasive features and/or provide the tumor with a pool of activated fibroblasts that produce molecules required for metastasis. Zeisberg et al. describe a new variation on this theme. Using genetically marked transgenic mice, they show that proliferating endothelial cells (the cells that form the inner layer of blood vessels) can also morph into mesenchymal cells resembling activated fibroblasts and that the latter cells are present in at least two distinct tumor types in mice. This “endothelial-mesenchymal” transition is promoted by transforming growth factor-1β1, a cytokine that also promotes EMT and that is abundant in many tumors. The next question is whether and how these intriguing cells contribute to tumor progression. — PAK

Cancer Res. 67, 10123 (2007).

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