O-6-ALKYLGUANINE-DNA ALKYLTRANSFERASE ACTIVITY IN SCHISTOSOMIASIS-ASSOCIATED HUMAN BLADDER-CANCER

O-6-Alkylguanine-DNA-alkyltransferase (ATase) activity was measured in extracts of 55 bladder tissue samples (46 tumour and nine uninvolved mucosal tissue) from Egyptian patients with schistosome-associated bladder carcinoma. Activity varied from 2.0 to 16.2 fmole ATase/mu g DNA (mean +/- S.D.; 5.6 +/- 4.0) or from 28 to 351 fmole ATase/mg protein (117 +/- 71). ATase levels in schistosome-associated bladder cancer tissues (5.6 +/- 4.0 fmole ATase/mu g DNA) tended to be lower than those observed in normal human bladder mucosal tissue (8.5 +/- 4.4 fmole ATase/mu g DNA). In a previous study (Badawi et al., Carcinogenesis, 1992, 13, 877-881) DNA-alkylation damage (O-6-methyldeoxyguanosine) was found in 44/46 of these schistomosome-associated bladder cancer samples at levels ranging from 0.012 to 0.485 mu mole O-6-MedG/mole deoxyguanosine. We now report an inverse correlation between the levels of methylation damage and ATase activity (r = - 0.67; P < 0.001). These observations encourage further investigations of the possible role of environmental alkylating agents in the aetiology of early bladder cancer associated with schistosomiasis.