DEVELOPMENT OF BIOREDUCTIVE MARKERS FOR TUMOR HYPOXIA

Hypoxic cells in tumours can be identified by exposing them to an immu nologically identifiable 2-nitroimidazole (NITP) with a theophylline s ubstituent which becomes bioreductively metabolised and binds to cellu lar macromolecules in the absence of oxygen. A range of monoclonal and polyclonal antibodies raised against theophylline or caffeine can ide ntify cells containing bound adducts of NITP, in some cases with highe r specificity than the standard product used. An alternative approach utilizes the very high specificity of FITC-avidin as a reagent to dete ct metabolic binding of a 2-nitroimidazole with a biotinylated side-ch ain (NIB), with the advantage of a single-step staining protocol. Both proliferating and hypoxic cell populations within tumours can be iden tified by simultaneous staining for incorporation of NITP and BrdUrd a nd this has shown that some cells incorporate both markers, suggesting that there is some overlap between the proliferating and hypoxic cell compartments.