Study paves way for treating bone metastasis in breast cancer patients

Calgary, AB – A multidisciplinary and international research team led by a University of Calgary scientist has been able to demonstrate, for the first time ever, how the hormone prolactin can escalate bone metastasis in breast cancer patients, setting the foundation for novel clinical treatments for bone metastasis in breast cancer patients.

“Bone metastasis is a highly debilitating part of the disease created by the spread of breast cancer,” said Carrie Simone Shemanko, associate professor in Department of Biological Sciences in the Faculty of Science. She is also the leader of the five-year research project recently published in the Journal of the National Cancer Institute. “It can lead to painful bone fractures, a significant loss of quality of life, and even death.”

According to the Canadian Cancer Society, breast cancer is the most common cancer among Canadian women (excluding non-melanoma skin cancers). It is also the second leading cause of death from cancer in Canadian women. In 2015, an estimated 25,000 women and 220 men will have been diagnosed with breast cancer. Of breast cancer patients whose disease has spread to other parts of their body, up to 85 percent will suffer bone metastasis, meaning their bones cells will have been disturbed by breast cancer cells.

“Bone is the most common site of metastasis in women whose cancer has spread from the breast,” said Shemanko, who led the research from her lab at the university, collaborating with other leading experts from the University of Calgary; Tampa, Florida; Paris, France; and Harbin, China.

To understand what happens at the site of bone metastasis, the research team grew breast cancer and bone cells in the lab and studied how prolactin plays a role in the communication between these cells.

“Our work indicates that women with high levels of the prolactin-receptor in their breast tumours experience bone metastasis earlier than women who have low levels,” says Shemanko. “We also discovered that these breast cancer cells travel to the bone where they can form new tumours in the bone.”

A total of 134 patient breast cancer biopsy samples and 17 matched breast cancer and bone biopsies were used in the study.

“What we found is that prolactin stimulates breast cancer cells to release factors that act as a language that is listened to by the bone cells,” she adds. “This cell language instructs them to break down the bone, creating an awful, vicious cycle of bone breakdown and tumour growth in the bone.”

This new understanding of the role of prolactin in the behaviour of breast cancer cells that have spread to the bone is expected to inform the development of new treatments to prevent the detrimental effects of bone metastasis. Shemanko’s team is already studying how certain drugs could specifically target the bone loss induced by the prolactin responsive breast cancer cells.

“Our research paves the way for more extensive inquiries into the role of prolactin in breast cancer metastasis and also for more large-scale studies,” she said. “I am humbled and motivated by the knowledge that we need to learn more and do more to continue to grow our understanding of the complex biology of cancer,” she added.

The research team’s work was supported by the Alberta Cancer Foundation, the Institute of Cancer Research of the Canadian Institutes of Health Research and the Canadian Breast Cancer Foundation.