Analysis of KIT (CD117) expression in gallbladder carcinomas by tissue microarray

KIT (CD117) is a transmembrane tyrosinase-kinase receptor which has been related to cell proliferation, differentiation, adhesion and control of apoptosis. If present, KIT may provide a suitable target for tumour therapy. In this study, we report the presence of KIT in primary and metastatic gallbladder carcinomas. Formalin-fixed and paraffin-embedded specimens of 57 primary gallbladder carcinomas and 18 corresponding metastases were stained using a tissue microarray technique and two different antibodies. Only three tumours stained for KIT. With a polyclonal antibody only one well differentiated papillary adenocarcinoma was immunoreactive. With a monoclonal antibody two additional poorly differentiated tubular adenocarcinoma showed weak and focal immunostaining. KIT immunoreactivity is infrequent in gallbladder carcinoma. Thus, routine screening of tumour tissues for KIT by immunohistochemistry appears to be cost-ineffective and cannot be recommended. Moreover, the lack of substantial KIT immunoreactivity in both primary and metastatic gallbladder carcinoma tissues does not provide a rationale to investigate imatinib mesylate therapy in clinical trials including patients with advanced disease.