[Orotate phosphoribosyl transferase in bladder cancer]

5-fluorouracil (5-FU) is an anticancer agent widely used against various tumors including bladder cancer. Orotate phosphoribosyl transferase (OPRT) is one of the key enzymes in metabolic pathways of 5-FU. We examined the possible relationship between OPRT activities of bladder cancer specimens and clinicopathological features. In addition, chemosensitivity to 5-FU was also examined. Bladder cancer specimens were obtained from 36 patients between November 1997 and January 2004. OPRT activity was measured by radioassay. In vitro chemosensitivity to 5-FU was assessed using histoculture drug response assay (HDRA). The mean OPRT activity in bladder cancer specimens was significantly higher than that in normal bladder specimens. In high-grade (G3) and invasive cancer specimens, mean OPRT activities were significantly higher than those in low grade (G1 and G2) and superficial cancer specimens, respectively. There was a significant correlation between OPRT activity and 5-FU sensitivity (r=0.571, p<0.01) in 19 cases whose OPRT activities and 5-FU sensitivities were assessed simultaneously. These results suggest that OPRT activity may be a good indicator of the malignant potential and sensitivity to 5-FU in bladder cancer.