Cytochrome P450 isoenzyme mRNA expression pattern in human urinary bladder malignancies and normal urothelium

This study was designed to analyze the cytochrome P450 isoenzyme mRNA expression pattern of transitional cell carcinomas of the bladder (N = 19) and normal urothelium (N = 10). In addition, biopsies from normal urothelium (N = 32) taken at the time of transurethral resection of bladder cancer in eight patients from surrounding histologically normal urothelium also were characterized concerning their specific cytochrome P450 mRNA expression pattern. A total of 13 of 19 of the analyzed tumor specimens (68%) revealed expression of cytochrome P450 1B1. Cytochrome P450 4B1 and 1A1 mRNA expression were detected in 79% (15 of 19) and 53% (10 of 19) of the tumor specimens, with no correlation between tumor stage and grade of the neoplasm. Biopsies from macroscopically and histologically normal urothelium from tumor-invaded bladders also showed expression of cytochrome P450 1B1 in 75% (24 of 32), 4B1 in 62.5% (20 of 32), and 1A1 in 50% (16 of 32). Furthermore, a 75% homology concerning cytochrome P450 1B1 and 4B1 mRNA expression was observed between the bladder tumor and the biopsies from this bladder. The polymerase chain reaction analysis of normal urothelium from normal bladders that do not harbor a neoplasm revealed CYP450 mRNA expression for CYP450 1A1 in 6 of 10; 1B1 in 5 of 10; 4B1 in 6 of 10; 2D6 in 2 of 10; and 2E1 in 2 of 10. According to our data, CYP450 1B1 mRNA expression is not tumor-specific. The present findings are the first to compare CYP450 expression in bladder cancer with biopsies from the same tumor-bearing bladder, and they indicate that, from the enzymatic point of view, bladder cancer also is a panurothelial field disease present in even normal urothelium.