Expression of xenobiotic metabolizing enzymes in tumours of the urinary bladder.

The cytochromes P450, epoxide hydrolase and glutathione S-transferases are several of the major groups of enzymes involved in the metabolism of xenobiotics and these enzymes may have a role in influencing the response of tumours to anti-cancer drugs. In this study the cell specific expression of individual xenobiotic metabolizing enzymes has been investigated using immunohistochemistry in primary transitional cell tumours of the urinary bladder. The cytochromes P450 CYP1A, CYP2C and CYP3A, were present in 68, 28 and 68% of tumours respectively and the expression of CYP1A correlated with bladder tumour grade (P = 0.03). Epoxide hydrolase was identified in 84% of tumours while the alpha, mu and pi forms of glutathione S-transferase were expressed in 56, 72 and 52% of tumours respectively. In normal bladder epoxide hydrolase and glutathione S-transferase pi were the main enzymes expressed while there was no expression of CYP2C.