EXPRESSION OF XENOBIOTIC-METABOLIZING ENZYMES IN TUMORS 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 r esponse of tumours to anti-cancer drugs. In this study the cell specif ic expression of individual xenobiotic metabolizing enzymes has been i nvestigated using immunohistochemistry in primary transitional cell tu mours of the urinary bladder. The cytochromes P450 CYP1A, CYP2C and CY P3A, were present in 68, 28 and 68% of tumours respectively and the ex pression of CYP1A correlated with bladder tumour grade (P=0.03). Epoxi de 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 glut athione S-transferase pi were the main enzymes expressed while there w as no expression of CYP2C.