Prevalence and importance of internal tandem duplications in exons 11 and 12 of c-kit in mast cell tumors of dogs.
OBJECTIVE
To determine the prevalence of activating internal tandem duplications (ITDs) in exons 11 and 12 of c-kit in mast cell tumors (MCTs) of dogs and to correlate these mutations with prognosis.


METHODS
157 formalin-fixed, paraffin-embedded MCTs from dogs in the pathology database of the Veterinary Medical Teaching Hospital at the University of California, Davis.


METHODS
Genomic DNA was isolated from tumor specimens and a polymerase chain reaction procedure was performed to determine whether there were ITDs in exons 11 and 12.


RESULTS
We identified ITDs in 1 of 12 (8%) grade-I, 42 of 119 (35%) grade-lI, and 9 of 26 (35%) grade-ll tumors (overall prevalence, 52 of 157 [33%]). Logistic regression analysis revealed that the odds of grade-II and -III tumors possessing an ITD were approximately 5 times greater than that for grade-I tumors, although these odds did not differ significantly. Although MCTs possessing an ITD were twice as likely to recur after excision and twice as likely to result in metastasis as those without an ITD, these values also did not differ significantly.


CONCLUSIONS
These results provide evidence that ITDs in c-kit occur frequently in MCTs of dogs. The high prevalence of c-kit activating mutations in MCTs of dogs combined with the relative abundance of mast cell disease in dogs provide an ideal naturally developing tumor in which to test the safety and efficacy of novel small-molecule kinase inhibitors such as imatinib mesylate.
Downing
Sue
S
Veterinary Cancer Referral Group, 1044 South Robertson Blvd, Los Angeles, CA 90035, USA.
Chien
May B
MB
Kass
Philip H
PH
Moore
Peter E
PE
London
Cheryl A
CA
D000818:Animals; D001483:Base Sequence; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D004283:Dog Diseases / Q000235:genetics*; D004285:Dogs; D005091:Exons / Q000235:genetics; D012515:Mast-Cell Sarcoma / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000662:veterinary; D019009:Proto-Oncogene Proteins c-kit / Q000737:chemistry / Q000235:genetics*; D012878:Skin Neoplasms / Q000235:genetics*; D020080:Tandem Repeat Sequences / Q000235:genetics*
D004273:DNA, Neoplasm; D019009:Proto-Oncogene Proteins c-kit