Comment on "Tumor Growth Need Not Be Driven by Rare Cancer Stem Cells"
James A. Kennedy,1,2
Frédéric Barabé,3,4,5
Armando G. Poeppl,1
Jean C. Y. Wang,1,6,7
John E. Dick1,2*
Kelly et al. (Brevia, 20 July 2007, p. 337) questioned xenotransplant
experiments supporting the cancer stem cell (CSC) hypothesis
because they found a high frequency of leukemia-initiating cells
(L-IC) in some transgenic mouse models. However, the CSC hypothesis
depends on prospective purification of cells with tumor-initiating
capacity, irrespective of frequency. Moreover, we found similar
L-IC frequencies in genetically comparable leukemias using syngeneic
or xenogeneic models.
2 Department of Molecular and Medical Genetics, University of Toronto, Toronto, Canada.
3 Department of Medicine, Laval University, Québec, Canada.
4 Department of Hematology, Enfant-Jesus Hospital, Québec, Canada.
5 Research Center in Infectious Diseases, Centre Hospitalier Universìtaire de Québec/Centre Hospitalier de l'Université Laval, Québec, Canada.
6 Division of Medical Oncology and Hematology, Department of Medicine, University Health Network, Toronto, Canada.
7 Department of Medicine, University of Toronto, Toronto, Canada.
* To whom correspondence should be addressed. E-mail: jdick{at}uhnres.utoronto.ca
