In the Oncology Laboratory
Center for Companion Animal Health, UC Davis, Spring 2004

The new oncology laboratory will foster collaborative research studies, and also provide space for residents and veterinary students to participate directly in bench research.

Medical oncologist Dr. Cheryl London, who specializes in the molecular biology of cancer, is co-leader of the Tumor Biology in Animals Program, part of the NCI Cancer Center Support Grant. One of the purposes of this program is to study the biologic behavior and treatment of spontaneous tumors in dogs and cats, as these tumors more closely mimic human cancer than do mouse tumors. Dr. London has several clinical trials underway for a variety of different cancers in dogs including mast cell tumors and sarcomas. One research project in her lab being conducted by Medical Oncology Resident Dr. Suzanne Shelly is focused on identifying a potential new treatment for canine melanoma.

Malignant melanoma in the dog is very resistant to standard therapies says Dr. London. In dogs, it develops in the oral cavity, spreads early on, and usually can’t be cured. In humans, it develops in the skin (from sun exposure). The cause is unknown, but the biology is the same. Melanoma in the dog makes a good biological model for the disease in humans.

Developing a Therapy for Canine Lymphoma
Dr. Steven Suter, lecturer in medical oncology and researcher in Dr. London’s laboratory, is working on a novel therapy for canine lymphoma.

Canine distemper virus has been shown to kill lymphoma cells in vitro. Canine lymphoma cell cultures are exposed to a canine distemper virus that carries a fluorescent marker. When viewed with a fluorescence microscope, infected cells glow green.

Dr. Suter is now working to demonstrate a similar result in dogs with lymphoma by introducing the distemper virus to the lymph nodes by internodal injection. The ultimate objective is to develop a therapy administered intravenously to lymphoma patients.

This CCAH research is being done in partnership with the Mayo Clinic in Rochester, Minnesota.

Canine Melanoma
Dr. Suzanne Shelley, resident in medical oncology, is looking for mutations in the cloned canine gene B-RAF, which is also a good model for human melanoma. A private company is working with the lab to develop inhibitors that will target mutant B-RAF.

Dr. Michael Kent, who has just joined the UC Davis faculty as a radiation oncologist, is working on the molecular mechanisms of resistance to radiation in dogs with melanoma and ways to overcome resistance. Malignant melanoma is resistant to radiation therapy in both humans and dogs.

"I am working to find the causes of radiation resistance in canine melanomas by looking at gene expression in cell lines made from some of our clinical patients,” says Dr. Kent. “We are also looking at the effects of irradiation on gene expression in the cell lines, and ways to block gene expression in resistant cells, so the melanoma cells will become more sensitive to irradiation."

Right: Dr. Michael Kent cultures cell lines from dogs with oral (mouth) melanomas. Above: (right) petri dish with cell colonies and (left) close-up view showing stained “resistant” cells that grew colonies after being irradiated.

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