Expression of cancer-testis genes in brain tumors: implications for cancer immunotherapy.

Cancer-testis (CT) genes have a restricted expression in normal tissues except testis and a wide range of tumor types. Testis is an immune-privileged site as a result of a blood barrier and lack of HLA class I expression on the surface of germ cells. Hence, if testis-specific genes are expressed in other tissues, they can be immunogenic. Expression of some CT genes in a high percentage of brain tumors makes them potential targets for immunotherapy. In addition, expression of CT genes in cancer stem cells may provide special targets for treatment of cancer recurrences and metastasis. The presence of antibodies against different CT genes in patients with advanced tumors has raised the possibility of polyvalent antitumor vaccine application.