title: Detection of thyroid cancer stem cells in papillary thyroid carcinoma.
abstract: BACKGROUND
  Special populations of cells that can efficiently initiate tumor growth have been characterized, and this feature supports the cancer stem cell theory. These cancer stem cell populations have been identified with CD44 and POU5F1. Most cancer stem cells express high levels of CD44 and low levels of CD24. In thyroid lesions, cancer stem cells have been detected in anaplastic carcinoma. However, little is known about the presence of cancer stem cells in papillary thyroid carcinoma (PTC), especially in recurrent PTC.
  
  
  OBJECTIVE
  PTC cells were labeled and sorted by flow cytometry to obtain two populations. Total RNA was prepared from cells with high CD44 and CD24 expressions (CD44+CD24+) and from cells with high CD44 and low CD24 expressions (CD44+CD24-). The expressions of the stem cell marker POU5F1 and several differentiated thyroid markers were measured via real-time PCR.
  
  
  RESULTS
  CD44+CD24- cells were present in all PTCs tested, and the percentage of these cells was higher in clinically aggressive recurrent PTC than in less aggressive primary PTCs. Higher expression of POU5F1 was found in CD44+CD24- cells compared with that of CD44+CD24+ cells. The expression of POU5F1 was higher in thyrospheroids grown in serum-free condition than in cells grown in the presence of serum from the same patient, and the tumor was initiated in mice using thyrospheroids.
  
  
  CONCLUSIONS
  The percentage of CD44+CD24- cells varied from tumor to tumor. Our findings suggest that cancer stem cells are present in PTC.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery (S-H.A.), College of Medicine, Seoul National University Bundang Hospital, Kyunggi-do 463-707, South Korea; and Departments of Head and Neck Surgery (Y.C.H., S.Y.L., G.L.C.), Pathology (M.D.W.), Molecular and Cellular Oncology (S.Y.L.), and Cancer Biology (G.L.C.), The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030.
authors.forename: Soon-Hyun
authors.initials: SH
authors.lastname: Ahn
authors.forename: Ying C
authors.initials: YC
authors.lastname: Henderson
authors.forename: Michelle D
authors.initials: MD
authors.lastname: Williams
authors.forename: Stephen Y
authors.initials: SY
authors.lastname: Lai
authors.forename: Gary L
authors.initials: GL
authors.lastname: Clayman
mesh_terms: D000818:Animals; D063646:Carcinogenesis / Q000378:metabolism / Q000473:pathology; D002291:Carcinoma, Papillary / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D005434:Flow Cytometry; D006801:Humans; D051379:Mice; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000473:pathology*; D013961:Thyroid Gland / Q000378:metabolism / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000378:metabolism / Q000473:pathology*