Identification of the two KIT isoforms and their expression status in canine hemangiosarcomas.

BACKGROUND: KIT is a tyrosine kinase growth factor receptor. High expression of KIT has been found in several tumors including canine hemangiosarcoma (HSA). This study investigated the correlation of KIT expression and c-kit sequence mutations in canine HSAs and benign hemangiomas (HAs). RESULTS: Immunohistochemistry (IHC) staining confirmed KIT expression in 94.4 % (34/36) of HSAs that was significantly higher than 0 % in HAs (0/16). Sequencing the entire c-kit coding region of HSAs and normal canine cerebellums (NCCs) revealed GNSK-deletion in exon 9. As for exon 9 genotyping by TA-cloning strategy, GNSK-deletion c-kit accounted for 48.6 % (68/140) colonies amplified from12 KIT-positive HSAs, a significantly higher frequency than 14.1 % (9/64) of colonies amplified from six NCCs. CONCLUSIONS: Due to the distinct expression pattern revealed by IHC, KIT might be used to distinguish benign or malignant vascular endothelial tumors. Moreover, the high incidence of GNSK-deletion c-kit in canine HSAs implicates KIT isoforms as possibly participating in the tumorigenesis of canine HSAs.