Full Paper

British Journal of Cancer advance online publication 3 November 2009; doi: 10.1038/sj.bjc.6605407

Tumour formation by single fibroblast growth factor receptor 3-positive rhabdomyosarcoma-initiating cells

M Hirotsu1,3, T Setoguchi1,3, Y Matsunoshita1, H Sasaki1, H Nagao1, H Gao1, K Sugimura2 and S Komiya1

  1. 1Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8520, Japan
  2. 2Faculty of Engineering, Department of Bioengineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065, Japan

Correspondence: Dr T Setoguchi, E-mail: setoro@m2.kufm.kagoshima-u.ac.jp

3These authors contributed equally to this work.

Received 6 August 2009; Revised 24 September 2009; Accepted 5 October 2009; Published online 3 November 2009.

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Abstract

Background:

  

The hypothesis that malignant tumours are generated by rare populations of cancer stem cells that are more tumourigenic than other cancer cells has gained increasing credence. The objective of this study was to identify and characterise a subpopulation of human sarcoma-initiating cells.

Methods:

  

We examined established rhabdomyosarcoma cell lines by flow cytometry. Tumourigenesis was examined by xenograft models. Real-time PCR and immunohistochemistry were performed to examine the gene expression using cell lines and biopsy specimens.

Results:

  

Rhabdomyosarcoma cell lines included small populations of fibroblast growth factor receptor 3 (FGFR3)-positive cells. FGFR3-positive KYM-1 and RD cells were more strongly tumourigenic than FGFR3-negative cells. In addition, xenoengraftment of 33% of single FGFR3-positive KYM-1 cells yielded tumour formation. Stem cell properties of FGFR3-positive cells were further established by real-time PCR, which demonstrated upregulation of undifferentiated cell markers and downregulation of differentiation markers. We showed that in the absence of serum, addition of basic fibroblast growth factor maintained and enriched FGFR3-positive cells. On the other hand, ciliary neurotrophic factor reduced the proportion of FGFR3-positive cells. Real-time PCR and immunohistochemical examination revealed that embryonal rhabdomyosarcoma patient biopsy specimens were found to over-express FGFR3.

Conclusions:

  

Our findings suggest that rhabdomyosarcoma cell lines include a minor subpopulation of FGFR3-positive sarcoma-initiating cells, which can be maintained indefinitely in culture and which is crucial for their malignancy.

Keywords:

rhabdomyosarcoma, sarcoma-initiating cells, cancer stem cell, fibroblast growth factor receptor 3 (FGFR3)