Study identifies a protein that makes breast cancer cells more invasive

Vancouver, BC – BC Cancer Agency scientists, in collaboration with international researchers, have identified the important role that a specific protein plays in breast cancer metastasis (spread of cancer cells to distant tissues or organs in the body), which may lead to new treatment targets in the future.

Published today in the journal Cancer Cell, the study found that high amounts of a protein called YB-I (Y-box binding protein-1), which is present in a subset of breast cancers, causes two different reactions in tumour cells. YB-1 actually slows or stops the growth of cancer cells at the primary site. However, it simultaneously enables these cells to become more invasive and to migrate to secondary sites, thereby potentially causing a recurrence of breast cancer when the cells re-activate.

“It’s disturbing that approximately 30% of breast cancer patients may develop metastatic disease, and that this may occur five to 10 years after their initial treatment,” says Dr Poul Sorensen, principal investigator of the study, a senior scientist at BC Cancer Agency, and the Johal Chair in the Childhood Cancer Research Program at the Child and Family Research Institute at BC Children’s Hospital. “It’s unclear why this happens, but scientists have hypothesized that certain drug-resistant cells persist after treatment and resume growth after being dormant for extended periods.”

“Our study has now identified that the YB-I protein ‘reprograms’ certain breast cancer cells to become dormant and to gain the ability to crawl out of the primary tumour site to other parts of the body, potentially giving rise to metastatic disease.”

The study was conducted using human breast cancer cells and validated using a variety of model systems.

“What is also significant about the discovery is that it suggests that conventional therapies may not work in eradicating breast cancer cells with high quantities of YB-1,” adds Dr Sorensen. “Conventional therapies are targeted at cancer cells that rapidly grow and divide, but these cells behave differently, since the YB-1 protein actually prevents cells from growing.”

The next step of the research is to learn more about cancer cells with high amounts of YB-1, such as what causes them to reactivate after they have migrated to secondary sites. Now that such cells have been identified, researchers can also begin to determine what their vulnerabilities might be for specific targeting.

“We need to understand how cancer cells over-expressing YB-1 are different from other cells so that we can find ways to eradicate them before they become reactivated causing metastatic disease,” says Dr Cristina Tognon, a researcher at the BC Cancer Agency, who along with Dr Valentina Evdokimova is co-first author of the study.