CXorf40B is a differentially expressed gene in brain metastatic human breast cancer.
Metastasis to the brain is a clinical problem in patients with breast cancer (1-3). We mined published microarray data (4, 5) to compare primary and metastatic tumor transcriptomes for the discovery of genes associated with brain metastasis in humans with metastatic breast cancer. We found that chromosome X open reading frame 40B, encoded by CXorf40B, was among the genes whose expression was most different in the brain metastases of patients with metastatic breast cancer as compared to primary tumors of the breast. CXorf40B mRNA was present at increased quantities in brain metastatic tissues as compared to primary tumors of the breast. Expression of CXorf40B in primary tumors was significantly correlated with patient distant metastasis-free survival. Modulation of CXorf40B expression may be relevant to the biology by which tumor cells metastasize from the breast to the brain in humans with metastatic breast cancer.