title: Identification and characterization of cancer stem cells in human head and neck squamous cell carcinoma.
abstract: BACKGROUND
  Current evidence suggests that initiation, growth, and invasion of cancer are driven by a small population of cancer stem cells (CSC). Previous studies have identified CD44+ cells as cancer stem cells in head and neck squamous cell carcinoma (HNSCC). However, CD44 is widely expressed in most cells in HNSCC tumor samples and several cell lines tested. We previously identified a small population of CD24+/CD44+ cells in HNSCC. In this study, we examined whether this population of cells may represent CSC in HNSCC.
  
  
  METHODS
  CD24+/CD44+ cells from HNSCC cell lines were sorted by flow cytometry, and their phenotype was confirmed by qRT-PCR. Their self-renewal and differentiation properties, clonogenicity in collagen gels, and response to anticancer drugs were tested in vitro. The tumorigenicity potential of CD24+/CD44+ cells was tested in athymic nude mice in vivo.
  
  
  RESULTS
  Our results show that CD24+/CD44+ cells possessed stemness characteristics of self-renewal and differentiation. CD24+/CD44+ cells showed higher cell invasion in vitro and made higher number of colonies in collagen gels compared to CD24-/CD44+ HNSCC cells. In addition, the CD24+/CD44+ cells were more chemo-resistant to gemcitabine and cisplatin compared to CD24-/CD44+ cells. In vivo, CD24+/CD44+ cells showed a tendency to generate larger tumors in nude mice compared to CD24-/CD44+ cell population.
  
  
  CONCLUSIONS
  Our study clearly demonstrates that a distinct small population of CD24+/CD44+ cells is present in HNSCC that shows stem cell-like properties. This distinct small population of cells should be further characterized and may provide an opportunity to target HNSCC CSC for therapy.
authors.forename: Jing
authors.initials: J
authors.lastname: Han
authors.forename: Toshio
authors.initials: T
authors.lastname: Fujisawa
authors.forename: Syed R
authors.initials: SR
authors.lastname: Husain
authors.affiliation: Tumor Vaccines and Biotechnology Branch, Division of Cellular and Gene Therapies, Center for Biologics Evaluation and Research, Food and Drug Administration, NIH Bldg 29B, Rm 2NN20, 29 Lincoln Dr,, Bethesda, MD, 20892, USA. raj.puri@fda.hhs.gov.
authors.forename: Raj K
authors.initials: RK
authors.lastname: Puri
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D051927:CD24 Antigen / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D006258:Head and Neck Neoplasms / Q000473:pathology*; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000473:pathology*; D000093542:Gemcitabine
chemical_list: D000970:Antineoplastic Agents; D051927:CD24 Antigen; D018960:Hyaluronan Receptors; D003841:Deoxycytidine; D002945:Cisplatin; D000093542:Gemcitabine