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Profile of Bret Pearson

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Dr. Bret Pearson

Dr. Bret Pearson, PhD

  • Scientist, Developmental & Stem Cell Biology
  • Assistant Professor, University of Toronto

1. Where are you from?/Where did you study?
I’m from Colorado and was born and raised near Denver. I did my undergraduate degree as a double major in genetics and bacteriology at the University of Wisconsin, Madison. After that I moved to the west and got my PhD with Dr. Chris Q. Doe at the University of Oregon. Finally, I did a post-doc with Dr. Alejandro Sánchez Alvarado at the University of Utah. It makes me tired just thinking about all that moving around.

2. What are you researching right now?
We are the first lab in Canada to use a new model system called: freshwater planarians. Planarians are found just about anywhere in the world where there is freshwater. In the United States planarians are commonly used in high school biology classes. They are really cool to high school kids because you can cut off their heads and they regenerate another head in about a week. You can even cut them into about 200 pieces and each piece will generate a new worm. They can regenerate because they have a huge number of adult stem cells. We are using them in medical research to try and understand how they coordinate their adult stem cells during regeneration.

One of the paradoxes with planarians is that they live for a very long time, probably for decades, and during that time, they have constant cell division but yet they don’t develop stem cell associated tumours. We’re wondering how they suppress tumour formation in their normal stem cell lineages and what genes may be involved in this process.

The really exciting thing is that the same genes which cause cancer in humans when mutated, affect stem cell proliferation in planarians in a similar way. This suggests that planarians will teach us new information about how cancer develops and will help us find new genes involved in this process. We have recently been working on the p53 gene as well as the retinoblastoma pathway.

3. Who is your all-time favourite scientist, and why?
I think to answer with an earlier physicist, such as Newton, is the easy way out. Plus I’m not a physicist, so my answer will have to be a biologist. There are two people I can think of if I want to go with a biologist who discovered something that saved the most lives and that would be either Louis Pasteur, with the germ theory of disease or Edward Jenner the pioneer of the small pox vaccine.

However, I think for my all-time favourite scientist, I will go with Charles Darwin. Science works by building up in small increments from what others have discovered before and large jumps in knowledge are rare. I feel like Darwin really made a huge jump in discovering that species were descended from each other. I use his theory almost every day and that is impressive considering that it is 150 years old. Because we’re working in this new system of planarians, we are always looking for the planarian version of human genes and the only way we can do that is because we know all organisms are related, thanks to Darwin.

4. What in your opinion is the single most important scientific breakthrough, and why?
I think that Dr. Edward Jenner’s discovery of the small pox vaccine and the concept of immunization in general is definitely the most important and has saved countless lives.

5. What are your major interests outside the lab?
I like to play sports, especially golf. I love being outdoors, hiking and camping. I’m also a big science-fiction reader.

6. Why science?
I don’t know if I chose science or if science chose me. For as long as I can remember I’ve always been interested in animals and biology. I had many biology books as a kid and I used to like looking through encyclopaedias. It was all that really interested me. My parents were very supportive and patient and encouraged me to go to the creek near our house and collect anything I wanted to and try and raise it in cages. I caught snakes and frogs and even owned exotic pets from pet stores like chinchillas. Our house was kind of a zoo really; it is amazing that they let it go on. Every organism was different and interesting to raise.

I knew in high school that I wanted to major in genetics in university and I chose University of Wisconsin because they were one of the few schools at the time which had a genetics major. So I started as a field biologist at a young age collecting things and I guess I never looked back after that.

7. Why SickKids?
For a long time I have known about the stem cell biology research being done at SickKids and the large stem cell community in Toronto. When I was on the job market, another stem cell researcher friend of mine mentioned that there was a job opening here and so I started looking into SickKids a little bit more. I was very impressed by the depth and breadth of the science that goes on here. The ability to be in a hospital setting and work on cancer topics was a huge draw as well. Both of my parents are cancer survivors, so I’ve always thought that if we only have a couple decades to be able to work on science in our own way, running a laboratory, better to work on a topic that affects both children and adults and is an unknown scientific problem like cancer. It was the perfect storm of a job. SickKids didn’t have anyone who works on planarians and I wanted to work on developmental biology, stem cell biology and cancer related topics. There are very few places in the world that offer an opportunity like SickKids does. So far, my time here has been great. 

8. What is the most controversial question in your field right now?
I think a big one is the origin of cancer. This has been quite the controversy for many years. The latency between the initial mutation and then the development of cancer is now thought to be at least a few years; the question is what is happening to cells in those in between years? There are no easy ways to study this question. For example, a graduate student cannot (or at least should not) undertake a ten year experiment. That would be an unpleasant PhD. That is part of the reason we use planarians. We can look at the entire stem cell population in adult animals and we can take away tumour suppressor genes and see what happens. We are getting an idea of how stem cells use tumour suppressors to be normal and what happens on small time scales when you take the tumour suppressor genes away. This is something that is hard to look at in other model systems. Our data supports the idea that cancers have a stem cell origin, but again that is very controversial.

9. What are you reading right now?
I’m actually reading Aldous Huxley’s A Brave New World right now. I would say I’m mildly enjoying it. When you consider when it was written it’s pretty impressive, but to me it’s just a really weird dystopian pseudo sci-fi novel. I kind of like the space operas a bit more than these politically-oriented older books. It’s definitely an interesting read though and I would recommend it.

In terms of science, I’m always reading new stem cell papers that seem to continuously be coming out these days. I’m currently reading Dr. Hans Clevers’ recent paper on intestinal stem cells.

10. If you could give one piece of advice to someone considering a research career, what would it be?
I would say it is important to understand the long slog that you’re in for. A lot of people come into graduate school thinking, I just need to show up, do the experiments, and I’ll publish my papers and move on. It doesn’t quite work that way because everyone hits tough times in their work. You have to understand that while research is extremely rewarding in the long run, there are some low points where nothing works. The people who succeed don’t get discouraged and are able to work through those tough times.

11. What will the new Research & Learning Tower mean to you?
Superficially, the new Tower means space. Right now space is tight for everyone in our current building. On a deeper level, the new Tower will bring together all of SickKids research, which is spread across several buildings right now. I think the idea of the “neighbourhoods” (several adjacent floors working on similar topics) in the design of the new Tower is going to facilitate interaction between researchers and build collaborations that are not possible when labs are spread out. It will certainly be an exciting place to work and carry out the next generation of cancer research!

November 2010

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