A fight against breast cancer

About one in eight cis women will develop breast cancer at some point in their lives.

In 2020 alone, over 2 million were diagnosed with breast cancer and 685,000 died from the disease. In the last five years, 7.8 million people lived with breast cancer, making it one of the most common cancers worldwide.

The impact of breast cancer is a growing concern, prompting research organizations to fund independent academic research projects with the aim of ensuring a brighter future for those affected. This has led to increased breast cancer innovations in recent decades.

Yvonne Myal, professor at the University of Manitoba and associate director of the Department of Pathology and principal investigator at the CancerCare Manitoba Research Institute, is at the forefront of innovative research advancing our understanding of how breast cancer develops.

The majority of Myal’s studies focus on prolactin-inducible protein (PIP) – a small secreted protein found in tissues within the body, including the breasts. She worked on this research for several years as a graduate student at the University of Manitoba.

According to Myal, high levels of PIP are found in the breast, and PIP is overproduced in benign cystic breast disease. She found that PIP is detectable in up to 90 percent of breast cancer cases

“It seemed to be linked to abnormalities and it must play a role in breast cancer,” she said.

Myal was involved in pioneering work on this secretory protein, including cloning the PIP gene, identifying its chromosomal location and creating the first genetically modified mouse models used to study the PIP gene.

Their laboratory studies have revealed that PIP plays some immune defense functions in the body.

Myal explained that PIP is used clinically to identify breast cancer cells that have spread throughout the body.

According to Myal, previous studies suggested that the presence of PIP in the early stages of breast cancer was a good thing because tumors responded better to treatment.

However, she pointed out that when found in metastatic cancer, it works differently and may serve a different function.

“It’s like a double-edged sword in that it protects in the early stages of breast cancer development, but in the later stages when there is metastasis, it seems to facilitate progression,” Myal said.

Claudin-1 and small breast epithelial mucin (SBEM) – both associated with breast cancer – are two other molecules Myal has focused on in her research career.

Myal’s current research focuses on using mouse models to understand PIP involvement in triple-negative breast cancer — an aggressive form of breast cancer that accounts for 15 to 25 percent of all breast cancers. Those diagnosed with triple-negative breast cancer survive, on average, about 10 months after diagnosis

“These cancers are difficult to treat,” she said. “They are resistant to current treatment and chemotherapy.”

Using these models in mice with a normal immune response, Myal explained that “tumours expressing PIP are retarded in growth compared to tumors which, our control, do not express PIP.”

“When we examined the metastases in the lungs in immunocompetent mice, the presence of PIP seemed to make the tumors more aggressive and metastatic,” she added.

On the other hand, when looking at mice with weakened immune systems, Myal found that it makes no difference.

“This is important information because we are trying to figure out what works in the metastatic state and how we as researchers can identify those things that would lead to clinical improvement and treatment,” she said.

Myal’s work is currently funded by organizations such as the National Sciences and Engineering Research Council of Canada, the Cancer Research Society and the Canadian Institutes of Health Research, facilitating the continued expansion of breast cancer research.

“I have a lot of employees,” Myal said. “Collaboration is key to succeeding and driving research answers forward.”

Myal has also mentored many students who went on to work in a variety of professions.

“You see me, but I represent a team,” she said. “I really believe in teamwork, I really believe in mentoring.”