Carbonyl reductase and NADPH cytochrome P450 reductase activities in humantumoral versus normal tissues

The use of bioreductive agents in enzyme-directed bioreductive therapy has been proposed to take advantage not only of hypoxia in tumours, but also of the presence of reductases that metabolise such compounds. In this study, we studied the activities of NADPH cytochrome P450 reductase (P450R) and ca rbonyl reductase (CR) in 17 human lung tumours and 18 human breast tumours, together with the corresponding normal tissues. For lung cancer but not fo r breast cancer there was a significant difference in the CR activity betwe en normal and tumour tissue. CR activity was increased with respect to the normal tissue between 2-fold and 40-fold indicating heterogeneity in tumour samples. No relationship was found between CR activity and the histologica l type, tumoral grade or TNM stage of the tumours. Although some variation in P450R activity in tumoral versus normal tissues was found in the majorit y of the samples studied, no significant differences could be demonstrated. (C) 1999 Elsevier Science Ltd. All rights reserved.