In a major breakthrough, a cancer-research team has identified a protein that may be the crucial reason behind breast cancer spreading to the brain.
Using cell models, the researchers at the University of Wisconsin-Madison found that breast cancer cells harness a protein called alphaB-crystallin to help them stick to endothelial cells that line the small blood vessels in the brain.
In addition, this protein enhances the penetration of breast cancer cells through the blood-brain barrier, which normally prevents cells and many molecules from entering the brain.
Once in the brain, breast cancer cells are able to form metastases i.e. spread of a cancer from one organ to another, said a new study published in the journal Clinical Cancer Research.
"We found that reducing the expression of alphaB-crystallin in breast cancer cells hindered the cells' ability to form brain metastases in mice," said Vincent Cryns, professor of medicine at University of Wisconsin School of Medicine and Public Health in the US.
"alphaB-crystallin may be a promising drug target that should be explored further," he added.
The researchers discovered that women with breast tumours that expressed alphaB-crystallin had a shorter survival than women with breast tumours that did not express this protein.
The also found breast tumours that expressed alphaB-crystallin were more likely to be triple-negative breast cancers, an aggressive type of cancer that lacks three receptors - estrogen receptor, progesterone receptor and HER-2.
Triple-negative breast cancers are known to have a high incidence of brain metastasis.
"Our findings suggest that alphaB-crystallin may contribute to the tendency of triple-negative breast cancers to metastasize to the brain and to their poor prognosis," said Cryns. Yet, he cautioned these findings need to be validated in additional studies.
Brain metastasis is a terrifying complication of advanced breast cancer, with a grim prognosis and few treatment options.
The cancer's spread to the brain is often undetected until patients start to develop symptoms such as seizures, headaches, and trouble thinking.
These studies were conducted in collaboration with researchers at the University of North Carolina at Chapel Hill, Duke University and other institutions.