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Analysis of c-KIT exon 11 mutations in canine gastrointestinal stromal tumours

Takanosu, M., Amano, S., Kagawa, Y.
The veterinary journal 2016 v.207 pp. 118-123
DNA, antibodies, chi-square distribution, cytoplasm, dogs, exons, gastrointestinal system, humans, immunohistochemistry, neoplasm cells, neoplasms, point mutation, reverse transcriptase polymerase chain reaction, staining
The aim of this study was to determine the type and frequency of c-KIT exon 11 mutations in canine gastrointestinal stromal tumours (GISTs) and investigate the association between the c-KIT mutation status and KIT immunohistochemical staining pattern. Mutations in exon 11 of c-KIT were examined in 46 formalin-fixed paraffin-embedded canine GISTs using PCR of genomic DNA and reverse transcription-PCR (RT-PCR) of cDNA.Exon 11 c-KIT mutations were detected in 15/46 (32.6%) cases by conventional PCR and 34/46 (73.9%) cases by RT-PCR; the mutation detection rate was significantly higher for RT-PCR (P = 0.004, Fisher's exact test). Ten different mutations, including deletion, internal tandem duplication and point mutations, were identified by RT-PCR. Immunohistochemistry was performed using an anti-KIT antibody; diffuse KIT staining was detected in the tumour cell cytoplasm in 32/46 (69.6%) cases and partial or stippled cytoplasmic staining of KIT was observed in 14/46 (30.4%) cases. Neither pattern was significantly associated with c-KIT exon 11 mutation status (P = 1.000, chi-square test). These data indicate that c-KIT exon 11 mutations occur frequently in canine GISTs, similar to human GISTs; however, there is no association between c-KIT mutations and the KIT expression pattern in canine GISTs. This study suggests that RT-PCR is more sensitive than conventional PCR for the detection of c-KIT mutations in canine GISTs.