Last week’s Science has another Brief on the ‘Stem Cell Theory of Cancer,’ with a nicely critical slant – Tumor Growth Need Not Be Driven by Rare Cancer Stem Cells, by Kelly et al.
Determining whether the growth of various tumors is sustained by most of the tumor cells or by a rare subpopulation has important ramifications for the design of novel therapies. Therefore, the cancer stem cell hypothesis merits more rigorous tests. For human tumors, ultimately this will require transfer of tumor cells into mice installed with all the requisite human support cells. Lastly, because the term “cancer stem cell” also currently designates the normal cell that founded the tumor, we suggest that the cells sustaining growth of an established tumor be referred to as “tumor-propagating cells.”
I dunno – I could think of a whole list of ways to refer to these cells other than “cancer stem cells” or “tumor-propagating cells.” Others that have been used include “tumor-initiating cells,” “cancer stem-like cells,” or tumor cells with a newly acquired mutation. Whatever you call them, there are serious problems with cancer stem cells as a theory of cancer (as opposed to just sharing a couple common features, such as self-renewal).
A merger of Hanahan & Weinberg’s model (2000) of trait acquisition in cancer progression and Merlo et al.‘s (2006) model of an evolving neoplastic ecosystem fit the collective data much better, as I’ve said before.
- Kelly PN, Dakic A, Adams JM, Nutt SL, Strasser A. Tumor growth need not be driven by rare cancer stem cells. Science. 2007 Jul 20;317(5836):337. Pubmed
- Merlo LM, Pepper JW, Reid BJ, Maley CC. Cancer as an evolutionary and ecological process. Nat Rev Cancer. 2006 Dec;6(12):924-35. Pubmed.
- Hanahan D, Weinberg RA. The hallmarks of cancer. Cell. 2000 Jan 7;100(1):57-70. Pubmed.