Adenocarcinomas of the lung or breast cancer, brain metastasis sources represent two very different courses of disease. In the case of breast, brain tumor occurs many years after removal from the primary tumor, suggesting that cancer cells lack certain functions scattered to grow in other organs. The analysis in patients revealed the existence of genes that are selectively involved in bone and lung metastases.

From these investigations, Massagué’s group had isolated cells preferentially infiltrate the brain from patients with advanced cancer. Through the analysis of gene expression in these cells and clinical samples, and corresponding functional analysis has identified some 243 genes. Were selected those whose overexpression in breast tumors are associated with a relapse in the brain (brain relapse) and have identified mediators of cancer cells pass through the blood brain barrier. It is concluded that the gene for cyclooxygenase COX-2 and ligand factor receptor (EGFR: epidermal growth factor receptor) or HBEGF are most important.

These genes had been found in tumor cells infiltrated the lungs, breast, but not in bone or liver, indicating that they are mediators of brain and lung metastases. We also have found a brain metastasis-specific gene, that of α-2 ,6-sialyl (ST6GALNAC5). The sialyl catalyze the transfer of sialic acid units to gangliosides and glycoproteins. The protein sialización power not only adherence to the endothelial cells of the brain, but its passage through the blood-brain.