Co-expression of KIT receptor and its ligand stem cell factor in Merkel cell carcinoma.
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.
Krasagakis
Konstantin
K
Department of Dermatology, Faculty of Medicine, University of Crete, Heraklion, Greece.
Kruger-Krasagakis
Sabine
S
Eberle
Jürgen
J
Tsatsakis
Aristidis
A
Tosca
Androniki D
AD
Stathopoulos
Efstathios N
EN
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*
D014408:Biomarkers, Tumor; D019089:Stem Cell Factor; D019009:Proto-Oncogene Proteins c-kit