title: c-Kit is not expressed in malignant mesothelioma.
abstract: Overexpression of KIT protein (CD117), the product of the c-kit gene, has been shown to have important prognostic and therapeutic implications for a number of malignant neoplasms. Previous studies have shown conflicting results regarding the expression of c-kit in malignant mesothelioma. To determine whether malignant mesothelioma expresses KIT, immunohistochemistry and RT-PCR were used to analyze archived tissue from 37 cases of mesothelioma. Although a subset of mesotheliomas demonstrated specific staining with the DAKO anti-KIT antibody, in each case staining was nuclear. We could not detect c-kit mRNA by a sensitive RT-PCR assay, even in cases with strong nuclear staining. Furthermore, a second anti-KIT antibody (Cell-Marque) only demonstrated staining in a single mesothelioma case and in none of the cases that demonstrated nuclear staining. We conclude that immunoreactivity for KIT in mesothelioma does not represent expression of the c-kit gene and may represent antibody cross-reaction with nuclear proteins. Our results raise doubt about previously reported expression of KIT in mesothelioma and consequently, the applicability of therapeutic agents that target the kinase activity of KIT.
authors.affiliation: Department of Pathology, University of California, San Francisco, California 94143, USA.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Horvai
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Zhidong
authors.initials: Z
authors.lastname: Xu
authors.forename: Miranda J
authors.initials: MJ
authors.lastname: Kramer
authors.forename: David M
authors.initials: DM
authors.lastname: Jablons
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Treseler
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D003429:Cross Reactions; D005189:False Positive Reactions; D006801:Humans; D007150:Immunohistochemistry; D008654:Mesothelioma / Q000378:metabolism* / Q000473:pathology; D010997:Pleural Neoplasms / Q000378:metabolism* / Q000473:pathology; D019009:Proto-Oncogene Proteins c-kit / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D014408:Biomarkers, Tumor; D019009:Proto-Oncogene Proteins c-kit