DANSYL FLUORIDE, A FLUORESCENT INHIBITOR FOR THE LOCATION OF TUMOR-CELLS IN HUMAN TISSUES

Dansyl fluoride (Dan-F), an active site directed fluorescent inhibitor of guanidinobenzoatase (GB), has been used for the location of tumour cells in frozen sections of human lung squamous cell carcinoma and co lonic carcinoma tissues. The tumour cell surfaces having active GB bin d Dan-F and fluoresce blue. The surrounding normal epithelial lung cel l surfaces fail to bind Dan-F and hence lack fluorescence, whilst the normal colon cell surfaces have another isoenzymic form of GB, bind Da n-F and fluoresce blue. Kinetic studies have shown that Dan-F is an ir reversible inhibitor of GB, and Dan-GB complexes are not dissociated w ith SDS and high salt concentration. However hydroxylamine (1 M) can d issociate Dan-GB complexes in the presence of 0.1% SDS, both on membra ne-bound and in free solution. These studies suggest that Dan-F is a p otent inhibitor of GB, and in very low concentration (3 x 10(-8) M) ca n be used as a novel fluorescent probe for the location of tumour cell s in histological sections of human tissues.