title: Psoriasin (S100A7) expression is altered during skin tumorigenesis.
abstract: BACKGROUND
  Psoriasin (S100A7) expression has previously been associated with psoriasiform hyperplasia as well as with tumor progression in breast cancer. Its expression profile for different stages of skin lesions is unknown. The aim of this study was to determine the relationship between psoriasin (S100A7) and tumor progression in skin.
  
  
  METHODS
  Psoriasin was assessed by immunohistochemistry and levels of expression determined by semi-quantitative scoring in skin biopsies from 50 patients. The cohort included normal skin, actinic keratosis, squamous carcinoma in-situ, invasive squamous cell carcinoma, and basal cell carcinoma.
  
  
  RESULTS
  In normal skin, psoriasin was rarely detected in epidermis but was expressed in underlying adnexae. In abnormal epidermis psoriasin was frequently expressed in abnormal keratinocytes in actinic keratosis, in-situ and invasive squamous cell carcinoma, but was rarely observed in the basal epidermal layer or in superficial or invasive basal cell carcinoma. The highest levels of expression were seen within squamous carcinoma in-situ. Significantly reduced levels of expression were observed in both unmatched (p = 0.0001) and matched (p < 0.004) invasive squamous cell carcinoma. Psoriasin expression within abnormal squamous lesions correlated with mitotic count (r = 0.54, p = 0.0036), however no significant relation was found with the intensity of dermal inflammatory cell infiltrates assessed within each pathology.
  
  
  CONCLUSIONS
  These results suggest that altered psoriasin expression occurs in abnormal epidermis and that downregulation may be related to the onset of invasion in squamous cell carcinoma in skin.
authors.affiliation: Department of Pathology, University of Manitoba, Faculty of Medicine, Winnipeg, Manitoba, Canada, R3E OW3. alowami@hotmail.com
authors.forename: Salem
authors.initials: S
authors.lastname: Alowami
authors.forename: Gefei
authors.initials: G
authors.lastname: Qing
authors.forename: Ethan
authors.initials: E
authors.lastname: Emberley
authors.forename: Linda
authors.initials: L
authors.lastname: Snell
authors.forename: Peter H
authors.initials: PH
authors.lastname: Watson
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D006801:Humans; D009361:Neoplasm Invasiveness; D000075023:S100 Calcium Binding Protein A7; D009418:S100 Proteins; D012878:Skin Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D002135:Calcium-Binding Proteins; D000075023:S100 Calcium Binding Protein A7; D009418:S100 Proteins; C089242:S100A7 protein, human