Brain tumors, unfortunately, do not respond to any known treatment. The blood-brain barrier performs a neuroprotective function by tightly controlling access to the brain; consequently it also impedes access of proteins as well as pharmacological agents to cerebral tissues. In order to treat brain tumors, it is therefore imperative to find vectors that can penetrate the blood–brain barrier and permit medications to do their part. Richard Béliveau and his team have recently shown that melanotransferrin is one such vector. They are currently studying the possibility of employing melanotransferrin as a new delivery system to target drugs directly to the brain.
Another major obstacle in the treatment of all types of cancer is the phenomenon of multiple drug resistance associated with an increase in P-glycoprotein, a protein transporter which shuttles drugs out of the cell. This protein is strongly expressed in cerebral capillaries, thereby increasing the impermeability of the blood-brain barrier to pharmacological agents. The laboratory studies P-glycoprotein’s mode of action and its interaction with other proteins, such as caveolin, in order to establish its biological function at the level of cerebral capillaries for the treatment of brain tumors.