A new study has explained why getting rid of breast cancer cells does not ensure that the disease won't spread to the brain.
City of Hope researchers have found that breast cancer cells disguise themselves as neurons, allowing them to hide from the immune system, cross the blood-brain barrier and begin to form ultimately-deadly brain tumors years after initial diagnosis.
Rahul Jandial, a City of Hope neurosurgeon who led the study, wanted to explore how breast cancer cells cross the blood-brain barrier, a separation of the blood circulating in the body from fluid in the brain, without being destroyed by the immune system.
Jandial said that his team wondered how a malignant breast cancer cell swimming in the bloodstream crossed into the brain and how it would survive in a completely new, foreign habitat.
Jandial and his team's hypothesis: Given that the brain is rich in many brain-specific types of chemicals and proteins, perhaps breast cancer cells exploit these resources by assuming similar properties.
These cancer cells could potentially deceive the immune system by blending in with the neurons, neurotransmitters, other types of proteins, cells and chemicals.
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Taking samples from brain tumors resulting from breast cancer, Jandial and his team found that the breast cancer cells were using the brain's most abundant chemical as a fuel source.
This chemical, GABA, is a neurotransmitter used for communication between neurons.
When compared to cells from non-metastatic breast cancer, the metastasized cells expressed a receptor for GABA, as well as for a protein that draws the transmitter into cells. This allowed the cancer cells to essentially masquerade as neurons.
Jandial added that breast cancer cells can be cellular chameleons (or masquerade as neurons) and spread to the brain.
The study will be published in the Proceedings of the National Academy of Sciences.