Diagnostic and therapeutic use of membrane proteins in cancer cells.

As proteomics technologies develop, increasing number of membrane-associated proteins specific for cancer cells are being discovered. These proteins are of great interest, particularly because they are rich in targets for antibodies. Amongst them candidate biomarkers for early tumor diagnosis, prognosis and treatment have been detected. The suitability of several membrane-associated proteins as targets for drugs or antibodies has already been tested in preclinical and clinical studies. The results were encouraging in some cases, but not in all. They demonstrate that each type of tumor has its specific "Achilles heel", and that suitable targets of cancer diagnosis and therapy must be found for each kind of neoplasm. This implies that membrane-associated proteins for each type of tumor cell need to be investigated. This review describes the current technologies of membrane protein characterization in a first part and subsequently summarizes the membrane associated proteins currently being tested as targets for diagnosis and treatment in breast, prostate, thyroid, and colon cancer. Their function will be explained and their role in tumor biology will be discussed.