title: Increased expression of an epidermal stem cell marker, cytokeratin 19, in cutaneous squamous cell carcinoma.
abstract: BACKGROUND
  Cytokeratin 19 (CK19) has been considered to be a putative marker for epidermal stem cells in the hair follicle bulge. Cumulative reports have shown that epidermal stem cells play an important role in skin carcinogenesis. However, to date there has been no report on the clinical alteration of the stem cells in squamous cell carcinoma (SCC).
  
  
  OBJECTIVE
  To investigate alteration of the stem cells and proliferating cells and to assess their relationship and potential contribution to SCC.
  
  
  METHODS
  Thirty paraffin-embedded neoplastic skin lesions, consisting of 10 cases each of actinic keratosis (AK), Bowen disease (BD) and SCC, were examined immunohistologically for CK19 and Ki-67.
  
  
  RESULTS
  Positive reactivity for CK19 was seen in 30% of AK, 50% of BD and 80% of SCC lesions. There was significantly higher expression levels of CK19 in SCC than in AK and BD (P < 0.05). In addition, BD lesions harboured a significantly higher number of CK19-positive cells than did AK lesions (P < 0.05). There were significant differences in Ki-67 labelling indices between AK and BD and between AK and SCC (P < 0.001), but not between BD and SCC (P > 0.05). Furthermore, a serial section comparison study showed that there was a minor population of cells co-expressing CK19 and Ki-67 in a subset of the tumour cells of SCC samples. The percentage of CK19+ cells significantly correlated with that of Ki67+ cells in all examined neoplastic skin lesions.
  
  
  CONCLUSIONS
  These results suggest that CK19 expression may be associated with the retention of stem cell characteristics or a state that is uncommitted to terminal squamous differentiation.
authors.affiliation: Department of Dermatology, Graduate School of Medical Sciences, Kyushu University, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.forename: M
authors.initials: M
authors.lastname: Takahara
authors.forename: M
authors.initials: M
authors.lastname: Kido
authors.forename: S
authors.initials: S
authors.lastname: Takeuchi
authors.forename: H
authors.initials: H
authors.lastname: Uchi
authors.forename: Y
authors.initials: Y
authors.lastname: Tu
authors.forename: Y
authors.initials: Y
authors.lastname: Moroi
authors.forename: M
authors.initials: M
authors.lastname: Furue
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000378:metabolism*; D016022:Case-Control Studies; D004817:Epidermis / Q000378:metabolism*; D006801:Humans; D053539:Keratin-19 / Q000378:metabolism*; D012878:Skin Neoplasms / Q000378:metabolism*; D013223:Statistics as Topic
chemical_list: D014408:Biomarkers, Tumor; D053539:Keratin-19