Gain-of-function mutations in the extracellular domain of KIT are common in canine mast cell tumors.
In the current study, we examined the types and frequency of KIT mutations in mast cell tumors from 191 dogs. Sequencing of reverse transcription-PCR products revealed alterations in 50 (26.2%) of the dogs. Most mutations were in exon 11 (n = 32), and of these, most were internal tandem duplications (n = 25) between residues 571 and 590. Within exon 11, there were two hotspots for mutations at codons 555-559 and 571-590. In addition, nine dogs had mutations in exon 8 and eight had mutations in exon 9. We selected the two most common mutants and two representative exon 11 mutants for further analysis. When expressed in Ba/F3 cells, they were constitutively tyrosine phosphorylated and induced growth factor-independent cell proliferation. AG1296, a tyrosine kinase inhibitor, dose dependently inhibited both the tyrosine phosphorylation of these mutants and their induction of growth factor-independent proliferation. This study shows that activating mutations in not only exon 11 but also exons 8 and 9 are common in canine mast cell tumors. These results also show that Ba/F3 cells can be used for the direct characterization of canine KIT mutants, eliminating the need to make equivalent mutations in the mouse or human genes.
Letard
Sébastien
S
Institut National de la Sante et de la Recherche Medicale, U891, Centre de Recherche en Cancérologie de Marseille, Molecular and Functional Hematopoiesis, Marseille F-13009, France.
Yang
Ying
Y
Hanssens
Katia
K
Palmérini
Fabienne
F
Leventhal
Phillip S
PS
Guéry
Stéphanie
S
Moussy
Alain
A
Kinet
Jean-Pierre
JP
Hermine
Olivier
O
Dubreuil
Patrice
P
D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D004285:Dogs; D005110:Extracellular Space / Q000737:chemistry*; D005260:Female; D005434:Flow Cytometry; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology; D008024:Ligands; D008297:Male; D008415:Mastocytosis / Q000235:genetics* / Q000473:pathology / Q000662:veterinary*; D051379:Mice; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D011110:Polymorphism, Genetic; D017434:Protein Structure, Tertiary; D019009:Proto-Oncogene Proteins c-kit / Q000737:chemistry* / Q000235:genetics*; D020032:Tyrphostins / Q000494:pharmacology
D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D050505:Mutant Proteins; D020032:Tyrphostins; C106250:6,7-dimethoxy-3-phenylquinoxaline; D019000:Phosphotyrosine; D019009:Proto-Oncogene Proteins c-kit