CYP4B1 is a possible risk factor for bladder cancer in humans

In experimental animals such as rats and rabbits, CYP4B1 has an important r ole in mutagenic activation of procarcinogens in bladders. In human bladder s, it is not clear whether CYP4B1 has such role or not. In the present stud y, human bladder microsomes activated a-aminofluorene which is a typical su bstrate for CYP4B1 and is a bladder carcinogen, CYP4B1 was detected in the human bladder microsomes by immunoblotting. Furthermore, we developed a mic roassay for CYP4B1 mRNA by performing real-time RT-PCR. Using this method, CYP4B1 mRNA levels were assayed in transurethal resection samples from the bladders of patients with bladder tumors. The bladder-tumor patients had a significantly higher expression of CYP4B1 than the nonbladder tumor patient s, These findings suggest that a high expression of CYP4B1 increases the ri sk of bladder tumor by activation of carcinogenic aromatic amines, This app roach could be an important tool in the assessment of human bladder cancer risk, (C) 2000 Academic Press.