Cancer Stem Cells Lose Support

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Science  13 Oct 2006:
Vol. 314, Issue 5797, pp. 225
DOI: 10.1126/science.314.5797.225b

Acute and chronic myeloid leukemia (AML and CML, respectively) are maintained by populations of rare cancer stem cells that divide infrequently and therefore escape the effects of conventional chemotherapies that are designed to destroy rapidly dividing cells. Defining the properties of cancer stem cells and, in particular, identifying which of these might render the cells selectively vulnerable to therapy, are topics of great current interest.

The normal stem cells that repopulate the hematopoietic system depend on interactions with stromal elements in their bone marrow microenvironment (niche) for survival and function. To explore whether cancer stem cells are similarly dependent, Jin et al. treated mice carrying human AML cells with an antibody to CD44, an adhesion molecule that is overexpressed on AML cells and that is involved in cell trafficking. Disruption of CD44 function markedly reduced the growth of leukemic cells in the mice, in part because the cells failed to migrate effectively to their bone marrow niche. Independent analysis of human CML stem cells by Krause et al. revealed a similar dependence on CD44. Importantly, in both studies, CD44 blockade had a preferential effect on cancer stem cells versus normal hematopoietic stem cells. These results suggest that certain leukemias may respond to treatments that disrupt the interaction of cancer stem cells with their supportive surroundings. — PAK

Nature Med. 12, 10.138/nm1483 (2006); 10.138/nm1489 (2006).

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