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Cancer Stem Cells
Version of Record online: 21 MAR 2011
Copyright © 2011 AlphaMed Press
Volume 29, Issue 3, pages 452–461, March 2011
How to Cite
Broadley, K. W. R., Hunn, M. K., Farrand, K. J., Price, K. M., Grasso, C., Miller, R. J., Hermans, I. F. and McConnell, M. J. (2011), Side Population is Not Necessary or Sufficient for a Cancer Stem Cell Phenotype in Glioblastoma Multiforme. STEM CELLS, 29: 452–461. doi: 10.1002/stem.582
Disclosure of potential conflicts of interest is found at the end of this article.
K.W.R.B.: conception and design, collection and/or assembly of data, data analysis and interpretation, manuscript writing; M.K.H.: collection and/or assembly of data, provision of study material or patients; K.J.F., K.M.P., C.G., and R.J.M.: collection and/or assembly of data, data analysis and interpretation; I.F.H.: conception and design, data analysis and interpretation, manuscript editing; M.J.M.: conception and design, collection and/or assembly of data, data analysis and interpretation, manuscript writing, final approval of manuscript.
First published online in STEM CELLSEXPRESS January 14, 2011.
- Issue online: 21 MAR 2011
- Version of Record online: 21 MAR 2011
- Accepted manuscript online: 23 DEC 2010 02:01PM EST
- Manuscript Accepted: 29 NOV 2010
- Manuscript Received: 3 JUN 2010
- Wellington Division of the Cancer Society of New Zealand and a Cancer Society of New Zealand. Grant Number: 08/10
- McKenzie Medical Research Fellowship
- Neurological Foundation and the Royal Australasian College of Surgeons
- SP cells
There is strong evidence for the existence of cancer stem cells (CSCs) in the aggressive brain tumor glioblastoma multiforme (GBM). These cells have stem-like self-renewal activity and increased tumor initiation capacity and are believed to be responsible for recurrence due to their resistance to therapy. Several techniques have been used to enrich for CSC, including growth in serum-free defined media to induce sphere formation, and isolation of a stem-like cell using exclusion of the fluorescent dye Hoechst 33342, the side population (SP). We show that sphere formation in GBM cell lines and primary GBM cells enriches for a CSC-like phenotype of increased self-renewal gene expression in vitro and increased tumor initiation in vivo. However, the SP was absent from all sphere cultures. Direct isolation of the SP from the GBM lines did not enrich for stem-like activity in vitro, and tumor-initiating activity was lower in sorted SP compared with non-SP and parental cells. Transient exposure to doxorubicin enhanced both CSC and SP frequency. However, doxorubicin treatment altered the cytometric profile and obscured the SP demonstrating the difficulty of identifying SP in cells under stress. Doxorubicin-exposed cells showed a transient increase in SP, but the doxorubicin-SP cells were still not enriched for a stem-like self-renewal phenotype. These data demonstrate that the GBM SP does not necessarily contribute to self-renewal or tumor initiation, key properties of a CSC, and we advise against using SP to enumerate or isolate CSC. STEM CELLS 2011;29:452–461