Differential Expression of , , and Is Associated with Brain Metastasis of ER-Negative Breast Cancers.

Background: Brain metastasis is considered one of the major causes of mortality in breast cancer patients. To invade the brain, tumor cells need to pass the blood-brain barrier by mechanisms that are partially understood. In primary ER-negative breast cancers that developed brain metastases, we found that some of the differentially expressed genes play roles in the T cell response. The present study aimed to identify genes involved in the formation of brain metastasis independently from the T cell response.

Method: Previously profiled primary breast cancer samples were reanalyzed. Genes that were found to be differentially expressed were confirmed by RT-PCR and by immunohistochemistry using an independent cohort of samples.

Results: and were overexpressed in the primary breast tumors that developed brain metastasis. expression was successfully validated at the protein level. was validated at both mRNA and protein levels. and mRNA overexpression were also found to be associated with cerebral metastasis in an external online database consisting of 204 primary breast cancers.

Conclusion: The overexpression of , and is associated with the invasion of breast cancer into the brain. Further studies to determine their specific function and potential value as brain metastasis biomarkers are required.