Progress 08/02/02 to 07/31/06
Outputs
The project PI, Dr. Cheryl London, has left University of California Davis and relocated to University of Ohio. The grant which funded Dr. London's study has been transferred to the University of Ohio, therefore this report will serve to terminate the UCD component of th eproject. Dr. London is currently collaborating with Kerstin Lindblad-Toh, PhD, Broad Institute at MIT and Harvard to conduct this study on mapping genes associated with canine mast cell tumors. They are collecting DNA samples of dogs affected with mast cell tumors and older healthy controls (preferably over 8 years of age) from Shar-Pei. Shar-Pei have about a 5-fold increased risk for mast cell cancer and the study hopes to get samples from 100 affected dogs and 100 unaffected dogs.
Impacts
This work will provide a more detailed understanding of the role of Kit mutations in tumor biology both in dogs and people.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
Mast cell tumors (MCTs) are the most frequently diagnosed malignant tumor of the dog. We have previously demonstrated that at least 30% of canine MCTs possess mutations in the proto-oncogene c-kit consisting of tandem duplications in exons 11/12 encoding the negative regulatory juxtamembrane domain. These mutations result in constitutive phosphorylation of Kit in the absence of ligand binding. Dysregulation of Kit has also been found to occur in many human tumors including aberrant expression (small cell lung carcinoma, genitourinary cancers) and mutation in the cytoplasmic domain leading to constitutive activation (mast cell disorders, gastrointestinal stromal tumors). Recent studies with various experimental kinase inhibitors suggest that inhibition of Kit signaling may be of significant benefit to patients with these malignancies. However, for their application to be successful, it is critical that the role of c-kit mutations in the initiation and progression of
neoplastic disorders be more clearly defined. The hypothesis underlying this proposal is that activating mutations of c-kit are associated with the development and progression of malignant mast cell disease through the promotion of cell survival and induction of metalloproteinase gene expression linked to invasion and metastasis. The specific aims of this study are: 1) to undertake a meticulous characterization of c-kit mutations in dog MCTs including their impact on the biologic behavior of MCTs, and identification of potential risk factors associated with their development; 2) to study the effect of Kit dysregulation on normal cell populations in vivo through the generation of transgenic mice expressing various forms of mutant c-kit under a highly regulated inducible promoter; and 3) to evaluate the effects of indolinone kinase inhibitors on dysregulated Kit both in vitro and in mouse models of Kit mutation. The integration of detailed investigations of Kit dysregulation in the
mouse with comprehensive studies of a spontaneous model of c-kit mutation in the dog will help to clarify the biological and biochemical consequences of such mutations. Moreover, the incorporation of kinase inhibitors into these studies offers a unique opportunity to evaluate the potential usefulness and efficacy of such agents in the treatment of neoplastic diseases in which Kit dysfunction is evident. We have generated all three transgenic lines, have intercrossed them with the rtTA mice, and have generated mast cells from bone marrow of these mice to confirm doxyxcyline inducible Kit expression. We are currently analyzing the mast cells expressing different Kit mutations for differences in gene expression and signal transduction.
Impacts
The work outlined in this proposal will provide a more detailed understanding of the role of Kit mutations in tumor biology both in dogs and people.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
We have completed generating our transgenic mice and are in the process of analyzing the effects of the mutations on mast cells both in vitro and in vivo. We have also completed our analysis of the effect of mutations on clinical behavior of canine mast cell tumors.
Impacts
The work outlined in this proposal will provide a more detailed understanding of the role of Kit mutations in tumor biology both in dogs and people.
Publications
- Downing S, Chien MB, Kass PH, Moore PF, London CA. Prevalence and significance of Kit internal tandem duplications in canine mast cell tumor. Am J Vet Res 63:1718-1723; 2002.
- Jones CLR, Grahn R, Chien MB, Lyons LA, London CA. Detection of c-kit mutations in canine mast cell tumors using fluoresecent polyacrylamide gel electrophoresis. Accepted for publication in J Vet Diag Invest; 2004.
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