Various malignant cancers have been found to contain a sub-population of stem cell-like tumour cells, or cancer stem cells (CSCs), however, culture methods for CSCs and the size of the fraction of CSCs in C6, which is a commonly used glioma cell line, remain controversial. In this study, we demonstrated that the C6 cell line contains a fraction of tumour cells that can form tumour spheres in a simplified serum-free neural stem cell medium and express CD133 and nestin, which are widely-used markers for brain CSCs. Immunohistochemistry and immunofluorescence confirmed the existence of CSCs both in the C6 cell line and C6 xenografts. Flow cytometry demonstrated that 4.02% of cells in the C6 cell line and 4.21% in the C6 xenografts presented as CSCs. These results confirm the fraction of CSCs in the C6 cell line and provide a simple and effective method for isolation of CSCs to study the initiation and progression of human glioma and, possibly, other malignant tumours.
PolyakKHahnWC: Roots and stems: Stem cells in cancer. Nat Med2006; 12: 296–300.
2.
WichaMSLiuSDontuG: Cancer stem cells: An old idea–a paradigm shift. Cancer Res2006; 66: 1883–1890.
3.
BissellMJLabargeMA: Context, tissue plasticity, and cancer: Are tumor stem cells also regulated by the microenvironment?. Cancer Cell2005; 7: 17–23.
4.
BapatSA: Evolution of cancer stem cells. Semin Cancer Biol2007; 17: 204–213.
5.
LiLNeavesWB: Normal stem cells and cancer stem cells: The niche matters. Cancer Res2006; 66: 4553–4557.
6.
AbbottA: Cancer: The root of the problem. Nature2006; 442: 742–743.
7.
BehbodFRosenJM: Will cancer stem cells provide new therapeutic targets?. Carcinogenesis2005; 26: 703–711.
8.
ChristqenMBallmaierMBruchhardtH: Identification of a distinct side population of cancer cells in the Cal-51 human breast carcinoma cell line. Mol Cell Biochem2007; 306: 201–212.
9.
ZhongXLiYPengF: Identification of tumorigenic retinal stem-like cells in human solid retinoblastomas. Int J Cancer2007; 121: 2125–2131.
10.
HoMMNgAVLamS: Side population in human lung cancer cell lines and tumors is enriched with stem-like cancer cells. Cancer Res2007; 67: 4827–4833.
11.
WangJGuoLPChenLZ: Identification of cancer stem cell-like side population cells in human nasopharyngeal carcinoma cell line. Cancer Res2007; 67: 3716–3724.
12.
GalliRBindaEOrfanelliU: Isolation and characterization of tumorigenic, stem-like neural precursors from human glioblastoma. Cancer Res2004; 64: 7011–7021.
13.
YiLZhouZHPingYF: Isolation and characterization of stem cell-like precursor cells from primary human anaplastic oligoastrocytoma. Mod Pathol2007; 20: 1061–1068.
14.
YuanXCurtinJXiongY: Isolation of cancer stem cells from adult glioblastoma multiforme. Oncogene2004; 23: 9392–9400.
15.
HemmatiHDNakanoILazareffJA: Cancerous stem cells can arise from pediatric brain tumors. Proc Natl Acad Sci USA2003; 100: 15178–15183.
16.
KangSKParkJBChaSH: Multipotent, dedifferentiated cancer stem-like cells from brain gliomas. Stem Cells Dev2006; 15: 423–435.
17.
PatrawalaLCalhounTSchneider-BroussardR: Side population is enriched in tumorigenic, stem-like cancer cells, whereas ABCG2+ and ABCG2− cancer cells are similarly tumorigenic. Cancer Res2005; 65: 6207–6219.
18.
YuS-CPingY-FYiL: Isolation and characterization of cancer stem cells from a human glioblastoma cell line U87. Cancer Lett2008; 265: 124–134.
19.
KondoTSetoguchiTTagaT: Persistence of a small subpopulation of cancer stem-like cells in the C6 glioma cell line. Proc Natl Acad Sci USA2004; 101: 781–786.
20.
ZhengXShenGYangX: Most C6 cells are cancer stem cells: Evidence from clonal and population analyses. Cancer Res2007; 67: 3691–3697.
21.
LapidotTSirardCVormoorJ: A cell initiating human acute myeloid leukaemia after transplantation into SClD mice. Nature1994; 367: 645–648.
22.
SellSPierceGB: Maturation arrest of stem cell differentiation is a common pathway for the cellular origin of teratocarcinomas and epithelial cancers. Lab Invest1994; 70: 6–22.
23.
MaitlandNJCollinsAT: Prostate cancer stem cells: A new target for therapy. J Clin Oncol2008; 26: 2862–2870.
24.
LiCHeidtDGDalerbaP: Identification of pancreatic cancer stem cells. Cancer Res2007; 67: 1030–1037.
25.
DeanMFojoTBatesS: Tumour stem cells and drug resistance. Nat Rev Cancer2005; 5: 275–284.
26.
BaoSWuQMcLendonRE: Glioma stem cells promote radioresistance by preferential activation of the DNA damage response. Nature2006; 444: 756–760.
27.
SalmaggiABoiardiAGelatiM: Glioblastoma-derived tumorospheres identify a population of tumor stem-like cells with angiogenic potential and enhanced multidrug resistance phenotype. Glia2006; 54: 850–860.
28.
LiuGYuanXZengZ: Analysis of gene expression and chemoresistance of CD133+ cancer stem cells in glioblastoma. Mol Cancer2006; 5: 67.
29.
EramoARicci-VitianiLZeunerA: Chemotherapy resistance of glioblastoma stem cells. Cell Death Differ2006; 13: 1238–1241.
30.
GhodsAJIrvinDLiuG: Spheres isolated from 9L gliosarcoma rat cell line possess chemoresistant and aggressive cancer stem-like cells. Stem Cells2007; 25: 1645–1653.
31.
WeiCGuo-MinWYu-JunL: Apoptosis resistance can be used in screening the markers of cancer stem cells. Med Hypotheses2006; 67: 1381–1383.
32.
IgnatovaTNKukekovVGLaywellED: Human cortical glial tumors contain neural stem-like cells expressing astroglial and neuronal markers in vitro. Glia2002; 39: 193–206.
33.
SinghSKClarkeIDTerasakiM: Identification of a cancer stem cell in human brain tumours. Cancer Res2003; 63: 5821–5828.
