Detection of c-kit mutations in canine mast cell tumors using the polymerase chain reaction technique

Abstract

Twenty-seven dogs with mast cell tumor conducted by the biopsy samples examined by histopathology and four samples from normal dogs which had been treated at Veterinary Teaching Animal Hospital, Kasetsart University were included. The purpose of the study was to identify the mutation pattern of c-kit proto-oncogene of tyrosine kinase that had internal tandem duplications (ITD) in exons 11 and 12 of tumor samples. Tumor DNA was amplified by polymerase chain reaction technique. The affected dogs were > 10 years old (50%), 6-10 years old (35%) and < 6 years old (15%). The tumor site was variable. The commonest site was cutaneous (34%). The mast cell tumor samples were divided into grade I (30 %), grade II (56 %) and grade III (15%). Mutation of the c-kit proto-oncogene was found in two dogs with grade II and III (7.4%) with ITD size of 43 and 52 base pairs. This result indicates c-kit proto-oncogene mutation is uncommon in dogs. Therefore, ITD detection is not a suitable diagnosis for mast cell tumor in dog but may be used as a predictive marker for tumor status especially in higher grade tumor. The drug response has been reported in dogs with the ITD. Therefore this test is useful in the application of the drugs therapy such as im-atinib and masitinib that can inhibit the mutation of ITDs of the c-kit proto-oncogene in the dog that are not suitable for surgery.