title: Co-expression of KIT receptor and its ligand stem cell factor in Merkel cell carcinoma.
abstract: OBJECTIVE
  KIT receptor has been implicated in the pathogenesis of cancer, either by mutation or autocrine activation. Merkel cell carcinoma (MCC) is a rare KIT-positive cutaneous tumor. We investigated the co-expression of KIT and its ligand stem cell factor (SCF) in MCC.
  
  
  METHODS
  Sixteen specimens from 13 MCC patients of various tumor stages were examined by immunohistochemistry for SCF, KIT, Ki67/MIB-1 and cleaved caspase 3 expression, and for apoptosis by TUNEL.
  
  
  RESULTS
  KIT was expressed in 13 of 16 tumors, and SCF in 15 of 16 specimens. Co-expression of KIT and SCF was detected in 12 of 16 tumors. KIT and SCF immunoreactivity scores were independent of tumor stage. Ki67/MIB-1 proliferation rates were high, whereas apoptosis rates were low, and did not depend on KIT or SCF expression.
  
  
  CONCLUSIONS
  Co-expression of KIT and SCF in a high percentage of MCC tumors hints to an autocrine mechanism. KIT and SCF expression in primary tumors and in metastases suggests an early event in Merkel cell transformation.
authors.affiliation: Department of Dermatology, Faculty of Medicine, University of Crete, Heraklion, Greece.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Krasagakis
authors.forename: Sabine
authors.initials: S
authors.lastname: Kruger-Krasagakis
authors.forename: Jürgen
authors.initials: J
authors.lastname: Eberle
authors.forename: Aristidis
authors.initials: A
authors.lastname: Tsatsakis
authors.forename: Androniki D
authors.initials: AD
authors.lastname: Tosca
authors.forename: Efstathios N
authors.initials: EN
authors.lastname: Stathopoulos
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis; D014408:Biomarkers, Tumor / Q000378:metabolism*; D015266:Carcinoma, Merkel Cell / Q000378:metabolism*; D049109:Cell Proliferation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008297:Male; D008875:Middle Aged; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D012878:Skin Neoplasms / Q000378:metabolism*; D019089:Stem Cell Factor / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D019089:Stem Cell Factor; D019009:Proto-Oncogene Proteins c-kit