Cancer genes: their clinical potential.

The central problem in cancer therapy is the poor selectivity of current systemic agents against the common solid tumours. The demonstration that unique segments of DNA, constant in location and conserved in evolution, are involved in growth control opens new avenues for basic and clinical research. The functions of the products of these oncogenes need to be elucidated. Examples of growth control functions include homology to growth factors, surface receptors, protein kinases and cell cycle control proteins. From DNA sequence data peptides predicted to be exposed within intact molecules have been constructed and used to produce monoclonal antibodies to oncogene products. Such antibodies have demonstrated the intracellular localisation of oncogene products and their cell cycle regulatory role. A battery of antibodies against the different oncogene products can be used to aid diagnosis and prognosis. Immunohistology and other methods permit the geographical and quantitative analysis of oncoprotein function in normal and neoplastic tissues. New tumour marker systems have been uncovered. Furthermore, by purification and biochemical analysis the molecular basis for the action of these proteins can be elucidated. It is likely that by the end of the decade new drugs that inhibit oncoprotein function will be available for clinical trial.