According to a recent study published in the journal Nature Cell Biology, aging is the primary risk factor for breast cancer in women. "Bipotent basal stem cells actively maintain the adult mammary ductal tree, but with age tissues atrophy," the authors wrote.
The University of Toronto Faculty of Medicine provided an example: "Think of tissue as a building that is constantly under renovation. The contractors would be 'metalloproteinases,' which are constantly working to demolish and reconstruct the tissue. The architects in this case, who are trying to reign in and direct the contractors, are known as 'tissue inhibitors of metalloproteinases' - or TIMPs. When the architect and the contractors don't communicate well, a building can fall down. In the case of tissue, the result can be cancer."
As we age, our bodies lose the ability to repair tissue as quickly as we did in our younger days. The researchers discovered during their tests with mice that without the TIMP1 and TIMP3, the available stem cells increased and remained functional.
"Normally you would see these pools of stem cells, which reach their peak at six months in the mice, start to decline. As a result, the mammary glands start to degenerate, which increases the risk of breast cancer occurring," explains lead author Rama Khokha, according to the press release. "However, we found that in these particular mice, the stem cells remained consistently high when we measured them at every stage of life."
Despite the large number of stem cells, the team found no increased risk of cancer.
"It's generally assumed that the presence of a large number of stem cells can lead to an increased cancer risk," said Khokha, according to the press release. "However, we found these mice had no greater predisposition to cancer."
So, what's next?
Khokha is working with her colleagues at the Princess Margaret Cancer Foundation to see how "altered tissue remodeling" could prevent cancer or provide a new treatment for cancer patients.
"It's a fundamental tissue that is constantly reorganizing. It develops at puberty. It goes through cycles of change in the adult female. New structures appear and regress," she said, according to the press release. "It is therefore a good system to explore in order to understand tissue maintenance and epithelial cell turnover - the cells that underlie carcinomas, the most frequent type of cancer."
