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A Canine c-kit Novel Mutation Isolated from a Gastrointestinal Stromal Tumor (GIST) Retains the Ability to Form Dimers but Lacks Autophosphorylation
by
and
Kei Shimakawa
1,†,
So Doge
2,†,
Masaki Michishita
2,
Eri Tanabe
1,
Tsuyoshi Tajima
3,
Masato Kobayashi
4,
Makoto Bonkobara
5,
Masami Watanabe
6,
Kazuhiko Ochiai
1,* and
Yoshikazu Tanaka
1 1
Laboratory of Veterinary Hygiene, School of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
2
Laboratory of Veterinary Pathology, School of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
3
Laboratory of Veterinary Pharmacology, School of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
4
Laboratory of Veterinary Reproduction, School of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
5
Laboratory of Veterinary Clinical Pathology, School of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
6
Laboratory of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8558, Japan
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Animals 2025, 15(10), 1444; https://doi.org/10.3390/ani15101444
Submission received: 2 April 2025
/
Revised: 13 May 2025
/
Accepted: 15 May 2025
/
Published: 16 May 2025
(This article belongs to the Section Companion Animals)
Simple Summary
Gastrointestinal stromal tumors are refractory tumors that affect both dogs and humans, and are partly caused by mutations in the c-kit gene. In this study, two novel mutations were identified in the c-kit gene in canine gastrointestinal tumor tissues: an alanine to threonine substitution at residue 434 and a phenylalanine to serine substitution at residue 436 (F436S). The F436S mutation is a loss-of-function mutation that does not aberrantly affect the intracellular molecular maturation mechanism but lacks the autophosphorylation function of KIT while maintaining the dimerization function required for the phosphorylation of downstream genes. Although gain-of-function mutations in canine KIT have been previously identified, this is the first report of a loss-of-function mutation.
Abstract
Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors that develop in the gastrointestinal tract; KIT mutations are present in both canine and human GISTs. In this study, genomic DNA was extracted from formalin-fixed paraffin-embedded (FFPE) sections of 55 canine GIST cases, and mutation searches were performed for exons 8, 9, and 11. The results revealed novel mutations, A434T and F436S, in exon 8. In contrast to the A434T mutation without functional changes, the F436S mutant retained its dimerization ability, but lost its phosphorylation function and attenuated downstream Akt signaling, which is reflected in wound healing and migration activities. A comparison of the subcellular localization of WT KIT and the F436S mutant revealed no differences. In silico simulations indicated that the F436S mutation alters the structure of the near-membrane region and that its effects may extend to the transmembrane and intracellular domains compared to the WT. F436S is a point mutation that affects the entire molecule because co-mutation with the F436S mutation and the known autophosphorylation mutation reduces the autophosphorylation abilities.
Keywords:
autophosphorylation; canine; c-kit; GIST; KIT; loss-of-function mutation
