Tag Archives: mammary tumors

Dogs help in breast cancer research

Cancer is one of the most frequent diseases not only in people, but in pets as well. Like people, dogs can also suffer from cancer of the mammary glands (mammary tumors). Dog mammary tumors are very similar to breast carcinoma in humans, and much more so than those of rats or mice, for example. For this reason, research on canine mammary tumors is important for human medicine as well. A study performed at the University of Zurich has now shown how similar mammary tumors are in both people and dogs.

Enni Markkanen, Vetsuisse-Fakultät Zürich, Untersuch Hund

Cancerous cells reprogram healthy cells

For the development of tumors and the progression of a carcinoma, not only the characteristics of the cancer cells themselves are decisive, but also the cells surrounding the tumor play a major role in this. Many tumors even have the capability to reprogram healthy cells in the tumor environment in a way that they start to support the growth of the cancerous cells. This mechanism plays an essential role in human breast carcinoma – but is it the same for dogs? The similarity of breast carcinoma in dogs and humans has been known for a long time. “But whether these tumor cells also influence the surrounding tissue in dogs the same way they do in humans was unknown until now”, explains Enni Markkanen of the Institute of Pharmacology and Toxicology of the Vetsuisse Faculty of the University of Zurich.

Archived tissues are of great value to the research

The researchers analyzed the surrounding tissue of canine mammary tumors using molecular biology and immunohistological methods. To do this, they could access the tissue archive of the Institute of Veterinary Pathology located at the Animal Hospital. “With the permission of our patient’s owners, we conduct pathological tests to better understand diseases,” says animal pathologist Alexandra Malbon. “In the process, we archive samples of various organs and tissues as these samples can be of great value to answer future research questions.”

Dogs suffering from cancer aid cancer research for humans

In the archived samples of mammary tumors from dog patients, Enni Markkanen and her team were able to prove that some cells in the vicinity of tumors behave the same way as the corresponding cells in humans: In the healthy tissue surrounding the tumor, substances are produced that promote tumor growth. “Simply speaking, the tumor enslaves its environment: It forces the surrounding cells to work for its benefit,” Markkanen adds. This mechanism works the same in both humans and dogs. For research on breast carcinoma, tumor tissue of dogs is therefore, among other reasons, much better suitable than tissue from rats or cells cultivated in the laboratory. “Importantly, however, we don’t view our dog patients as test subjects for cancer research,” Markkanen says. “But they can help us to better understand breast carcinoma in both dogs and humans and fight it more effectively.”

Source:  University of Zurich media statement

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Breast cancer in dogs

A PhD project at the Norwegian School of Veterinary Science has been studying the genetics behind mammary tumours in dogs.  Breast cancer is the most common form of cancer in female dogs.

A mammary tumor in a dog (Photo by Veronica Kristiansen)

A mammary tumour in a dog (Photo by Veronica Kristiansen)

Kaja Sverdrup Borge’s PhD project has led to the identification of genetic changes associated with these types of tumour.

Borge studied known risk genes in dogs to learn more about the genes that predispose dogs to canine mammary tumours. These genes are already known to be linked to cancer in humans. Borge discovered that there was a large variation in these genes from breed to breed. Some of the variants proved to have a detrimental effect and could lead to a potential change in the risk of developing cancer.

Borge compared the incidence of these genes in different groups of English springer spaniels with and without mammary tumours. The genes were also studied in another group of dogs from breeds having either a high or low incidence of mammary tumours. The results of these analyses indicate that variants of the oestrogen receptor gene are associated with the risk of English springer spanieldeveloping mammary tumours in dogs.

Borge examined canine mammary tumours in order to identify mutations which have arisen in tumours and may therefore be involved in the development of cancer. She focused on changes in the number of gene copies where there was either a decrease or increase in gene areas in the tumours.

She found a large number of mutations and the number of aberrations increased, the more malignant the tumours turned out to be. She detected major cancer genes known to occur in humans but also identified new areas. Borge also demonstrated that linking detailed histopathological parameters from mammary tumour diagnostics to genetic mutations could help to chart specific genes that lead to the growth of tumours and to more malignant types of cancer.

Increased knowledge about the genetic changes which cause cancer is essential for the prevention, diagnosis and treatment of the disease.  Because of the similarities between carcinogenic gene mutations in both canine and human breast cancer, studying breast cancer in dogs also has benefits for the study of breast cancer in humans.

Source:  Media statement from Norwegian School of Veterinary Science