Identification of side population cells (stem-like cell population) in pediatric solid tumor cell lines.
OBJECTIVE
Recent evidence has supported the cancer stem cell theory that cancer contains a small number of cancer stem cells (CSC) as a reservoir of cancer cells. Only the CSC, but not most of the remaining constituent cancer cells, are thought to be responsible for tumorigenesis, progression, and metastasis as well as cancer relapse, suggesting that the CSC should be targeted to eradicate the cancer. Side population (SP) cells isolated by fluorescence-activated cell sorting (FACS) using Hoechst dye are known to be enriched in stem cells in various normal tissues as well as cancers. The authors investigated whether such stem-like SP cells may exist in pediatric solid tumors (PSTs).


METHODS
Sixteen pediatric tumor cell lines including 7 neuroblastomas, 4 rhabdomyosarcomas, and 5 Ewing's sarcomas were used for FACS analysis. Analysis of SP cells based on the exclusion of the DNA binding dye, Hoechst 33342, with and without verapamil using FACS was performed.


RESULTS
One Ewing's sarcoma cell line did not show an SP fraction, and only a small fraction of SP cells (0.12%-14.6%) was detected in the other 15 cell lines. These SP cells were all sensitive to verapamil.


CONCLUSIONS
This study suggested that most PSTs would contain a small fraction of SP cells (possible stem-like population). Targeting the CSC will provide a novel treatment strategy to eradicate refractory PSTs.
Komuro
Hiroaki
H
Department of Pediatric Surgery, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan. hiro-kom@md.tsukuba.ac.jp
Saihara
Ryoko
R
Shinya
Miki
M
Takita
Junko
J
Kaneko
Setsuko
S
Kaneko
Michio
M
Hayashi
Yasuhide
Y
D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor / Q000187:drug effects / Q000473:pathology; D002469:Cell Separation; D002648:Child; D002675:Child, Preschool; D019008:Drug Resistance, Neoplasm; D005434:Flow Cytometry; D006801:Humans; D009369:Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000473:pathology*; D009447:Neuroblastoma / Q000188:drug therapy / Q000473:pathology; D012208:Rhabdomyosarcoma / Q000188:drug therapy / Q000473:pathology; D012494:Sampling Studies; D012512:Sarcoma, Ewing / Q000188:drug therapy / Q000473:pathology; D012680:Sensitivity and Specificity; D014410:Tumor Stem Cell Assay; D014700:Verapamil / Q000494:pharmacology*
D014700:Verapamil