title: Immuno-histochemical evaluation of solar lentigines: The association of KGF/KGFR and other factors with lesion development.
abstract: BACKGROUND
  Solar lentigines (SLs) are macular hyperpigmented lesions associated with sun exposure and age. Histopathologically, SLs are defined by a hyperpigmented basal layer and elongated rete ridges. The molecular mechanisms involved in the formation and the development of SLs are not completely understood. Our earlier data show that keratinocyte growth factor (KGF) induces hyperpigmentary lesions with histological resemblance to SLs.
  
  
  OBJECTIVE
  To investigate the association of KGF/KGF receptor (KGFR) and other pigmentary genes with the progression of SL development. To better understand the possible role of KGF in the pathology of SLs.
  
  
  METHODS
  Archived human skin biopsies (24 SLs and 14 healthy skins) were studied using immunohistochemistry for KGF/KGFR, proliferation marker Ki67, stem cell marker keratin-15 (K15), tyrosinase (TYR), stem cell factor (SCF), and protease-activated receptor-2 (PAR-2).
  
  
  RESULTS
  An increase in TYR-positive cells and expression was found throughout SL progression, as compared to normal skin. The levels of KGF, KGFR, SCF, Ki67 and PAR-2 varied during SL progression. Ki67, K15 and KGF/KGFR were significantly upregulated at early-mid SL stages. The latest-stage SLs expressed the lowest levels of KGF, KGFR, SCF, Ki67 and PAR-2.
  
  
  CONCLUSIONS
  The upregulation of KGF/KGFR might induce the formation of rete ridges and hyperpigmentation. The reduced levels of all examined proteins (except TYR and K15) suggest a possible inactive status (dormancy or quiescence) of advanced lesions.
authors.affiliation: The Johnson & Johnson Skin Research Center, Consumer Product Worldwide, A Unit of Johnson & Johnson Consumer Companies, Inc., 199 Grandview Rd., Skillman, NJ 08558, USA.
authors.forename: Connie B
authors.initials: CB
authors.lastname: Lin
authors.forename: Yaping
authors.initials: Y
authors.lastname: Hu
authors.forename: Dianne
authors.initials: D
authors.lastname: Rossetti
authors.forename: Nannan
authors.initials: N
authors.lastname: Chen
authors.forename: Cassarino
authors.initials: C
authors.lastname: David
authors.forename: Andrzej
authors.initials: A
authors.lastname: Slominski
authors.forename: Miri
authors.initials: M
authors.lastname: Seiberg
mesh_terms: D000368:Aged; D001706:Biopsy; D016022:Case-Control Studies; D018450:Disease Progression; D051523:Fibroblast Growth Factor 7 / Q000378:metabolism*; D006801:Humans; D017495:Hyperpigmentation / Q000378:metabolism* / Q000473:pathology*; D053569:Keratin-15 / Q000378:metabolism; D008875:Middle Aged; D014442:Monophenol Monooxygenase / Q000378:metabolism; D051497:Receptor, Fibroblast Growth Factor, Type 2 / Q000378:metabolism*; D044464:Receptor, PAR-2 / Q000378:metabolism; D012867:Skin / Q000378:metabolism* / Q000473:pathology*; D015595:Skin Aging / Q000473:pathology*; D019089:Stem Cell Factor / Q000378:metabolism
chemical_list: C496453:FGF7 protein, human; D053569:Keratin-15; D044464:Receptor, PAR-2; D019089:Stem Cell Factor; D051523:Fibroblast Growth Factor 7; D014442:Monophenol Monooxygenase; D051497:Receptor, Fibroblast Growth Factor, Type 2; C065104:keratinocyte growth factor receptor