title: The challenge of tumor heterogeneity--different phenotypes of cancer stem cells in a head and neck squamous cell carcinoma xenograft mouse model.
abstract: OBJECTIVE
  Besides late diagnosis, tumor metastasis and cancer relapse are the main reasons for the poor prognosis of patients with head and neck cancer. Several investigations have shown that tumor is of heterogeneous molecularity consisting of several subpopulations, with a broad range of biological behaviors. The ability and potential of tumor to infiltrate into vessels and into neighbouring organs, as well as the resistance to chemotherapeutical cancer therapy may be caused by cancer stem cells (CSCs). The aim of the present study was to illuminate the role and behaviour of (CD44) and (ALDH1A1) as tumor stem cell markers in a xenograft mouse model of squamous cell carcinoma.
  
  
  METHODS
  Five female NMRI-Foxn1nu mice were injected with five million Detroit 562 cells (100 μl). After sacrifice of the mice, tumors were excised. Then ALDH1A1, CD44, (EGFR), CD31 and Ki 67 were detected as molecular markers for tumor stem cells by immunohistopathology and immunofluorescence.
  
  
  RESULTS
  The amount of putative CSC marker proteins CD44 and ALDH1A1 vary. ALDH1A1high tumor cells express low levels of CD44 and EGFR. The CD44+high expressers also exhibit expression of high levels of the EGFR. CSCs must be sub-classified depending on their expression of marker proteins.
  
  
  CONCLUSIONS
  We assume that CSCs can also be sub-classified into migratory and stationary CSCs. ALDH1A1high/CD44low/EGFRlow tumor cells may be stationary and quiescent, whereas ALDH1A1-/CD44high/EGFRhigh expressers have a migratory, invasive nature. It is likely that a regulatory mechanism, as yet unknown, controls this conversion, from quiescent to active cancer stem cells.
authors: ENT Department, Medical School, Goethe University, and University Hospital, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany.
authors: Christin
authors: C
authors: Geißler
authors: Markus
authors: M
authors: Hambek
authors: Martin
authors: M
authors: Leinung
authors: Marc
authors: M
authors: Diensthuber
authors: Davina
authors: D
authors: Gassner
authors: Timo
authors: T
authors: Stöver
authors: Jens
authors: J
authors: Wagenblast
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000276:immunology / Q000473:pathology*; D005260:Female; D006258:Head and Neck Neoplasms / Q000276:immunology / Q000473:pathology*; D016130:Immunophenotyping; D051379:Mice; D008954:Models, Biological; D014411:Neoplastic Stem Cells / Q000473:pathology*; D014183:Transplantation, Heterologous