Dr. Tak Mak

Director, The Campbell Family Institute for Breast Cancer Research, Princess Margaret Hospital
Researcher of the month: 
Sep 2009

Beating back breast cancer, one gene at a time

One of the most honoured scientists in Canada is Dr. Tak Mak, who has come a long way from his boyhood in Hong Kong. As a child growing up in the then-British colony, he confesses he was not much interested in school. Today, he is a professor at the University of Toronto, where he works with genetically modified “knock-out” mice to better understand the causes of cancer.

Dr. Mak became a world-renowned researcher in 1984, when he identified the gene that is responsible for making T-cell receptors in the body. T-cells are the body’s defense cells, which help fight viral infections, “Helper” T-cells possess receptors that can identify viruses, and signal “killer” T-cells to attack. In discovering the gene that controls the production of these receptors, Dr. Mak made an enormous breakthrough in the understanding of the body’s immune system.

The T-cell receptors are possibly the most important element of the immune system –they allow T-cells to distinguish “self” from “non-self.” Identifying this gene may lead to better treatments for a whole host of immune-disorders and other related conditions, from diabetes to cancer.

To understand how T-cells work, Dr. Mak needed to understand a great deal about cell-apoptosis, which led to the next phase of his career. Apoptosis is cell death. Immune cells, like all cells, need an “off switch” that will kill them when their work is done. This has to happen in the correct number – if too many T-cells die, the immune system is weakened. If not enough die, the system becomes too strong, and begins to attack the body.

Similarly, cancer is effectively cell apoptosis gone wrong – cancer cells won’t die, and therefore grow uncontrolled. With Dr. Mak’s understanding of genes and cell death, moving into cancer was a natural progression for his research when he joined the University of Toronto.

Today, Dr. Mak specializes in investigating cancer – he joined the Campbell Family Institute for Breast Cancer at Toronto’s Princess Margaret Hospital in 2004 – using knock-out mouse models. By creating mutant mice that lack certain genes, Dr. Mak is able to learn the role of these genes. In so doing, he is able to understand how changes in cell growth and death affect cancer initiation, progression and death.

Breast cancer strikes over 20,000 women in Canada every year, and Dr. Mak follows several research paths to combat it. In addition to mouse models, he also studies fruit flies, whose faster breeding rate allows for speedier experiments.

This multi-pronged, dedicated approach has already led to results – Dr. Mak has made many promising genetic discoveries, as well as identified growth factors that might slow or stop the spread of certain kinds of cancers.

Dr. Mak’s work has been widely recognized in Canada and abroad. He is an Officer of the Order of Canada, a member of the London’s prestigious Royal Society, and winner of Canada’s Gairdner and Izaak Walton Killam prizes. In addition, he has been honoured from Germany to Saudi Arabia.

The recognition is not what drives the modest doctor to keep striving to find treatments for breast cancer.

“It’s the number one cause of death for young women,” says Mak. “That’s a lot of mothers, a lot of children, a lot of daughters, a lot of wives. A lot of reasons to do breast cancer research.”

Funding sources for Dr. Mak’s research include the Amgen Institute, the Ontario Cancer Research Network (OCRN), and the Canada Foundation for Innovation.