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Scientists attempt to fight cancer by making human DNA from dogs

Illustration for article titled Scientists attempt to fight cancer by making human DNA from dogs

Lymphoma is a cancer of certain cells in the immune system. Many genes are thought to be associated with it, but scientists have pinpointed a few by making dog DNA into human DNA.


Non-Hodgkin's lymphoma can be any of a group of cancers of the white blood cells - the lymphocytes. In 2010, there were over 65,000 new cases in the United States, and 20,000 deaths. Over the past few decades, many different genes have been associated with non-Hodgkin's lymphoma, but there were so many different variables that not many of them could be isolated as most essential to the cancer. Recently scientists thought of a way of stripping away non-associated genes by going way outside the human gene pool.

Dogs also get non-Hodgkin's lymphoma. They have long been subject to genetic selection, leaving extremely controlled test groups. A population of purebred dogs has a very limited number of genetic variation - far less variation than any human gene pool. Scientists took genetic samples from dogs with lymphoma, and rearranged their genes so that the dog DNA was sequenced as human DNA. Scientists then compared that DNA to the DNA of humans with lymphoma.


Doctor Matthew Breen of North Carolina State University head the project and has this to say about the results:

"In essence, we stripped the background noise from the human data. Lymphoma genomics is a lot more complex in human patients than in dog patients. This study tells us that while both humans and dogs have comparable disease at the clinical and cellular level, the genetic changes associated with the same cancers are much less complex in the dog. This suggests that maybe there is a lot of genetic noise in the human cancers that are not essential components of the process. While human studies have been looking in numerous places in the genome, the dog data indicate we need to focus on what's shared, and these are very few regions."

Finding out what genes are vital to the cancer in every life form, and what genes are human variations, can lead to more effective cancer-fighting genetic strategies.

Via Physorg, the National Cancer Institute, and NCSU.

Image via Shutterstock


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Dr Emilio Lizardo

Well, it could mean that the excess stuff in humans is just noise. Or it could mean that the disease is more complex and heterogeneous than in dogs. Unfortunately, it's likely to be the latter. Lymphoma, like most cancers is many different diseases. It is more of a final common pathway than an individual disease.

Think of it as the difference between genotype and phenotype. Many different genotypes result in the same phenotype. So why is it I can treat the same disease (phenotype) with the same chemotherapy and roughly half the people are cured and half aren't? Different genotypes being expressed as the same phenotype. Traditionally, we have looked for clinical features to make prognostic predictions. The most popular one for lymphoma these days is called IPI or the International Prognostic Index. It looks at stage, age, LDH (a blood test) and the number of extranodal sites involved by the cancer and predicts long term odds of cure. It's better than just looking at stage. However, it isn't good enough to jsutify variations in treatments except in a few circumstances. Everybody is trying to come out with a better IPI. I was at a meeting a few years back where an expert from San Francisco was debating the superiority of her IPI modification vs a doc from Buffalo, NY. In the middle of it all an expert from MD Anderson got up and said they were both wrong and his was going to be shown to be better than the rest. Actually, all of them are probably wrong. The future is what this article hints at. We need to discover the exact cellular processes that go wrong and learn how to interfere with them. Some of this is already happening in some diseases and we are getting better and better at it every year. A few diseases are very homogeneous and simple and the vast majority of people with them can be treated now that we have identified the problem and are able to treat it. Tyrosine kinase inhibitors like imatinib virtually cure most chronic myelogenous leukemia. Other disease are far more complex and we have much farther to go. I'm still giving chemotherapy but the promise is great and this is the future of oncology.

In general, cancer and cancer treatment is much more complex in higher animals than lower ones. It is much easier to cure or cause cancer in mice than in humans, just look at how many drugs you have heard about in the news that were going to be great because they cured cancer in mice. Most of them never make it to market.