[Preparation of anti-OPRT antibody for immunochemical detection].

Orotate phosphoribosyl transferase (OPRT, EC 2.4.2.10) is a key enzyme in the anabolism of 5-fluorouracil (5 FU), and its expression in tumor is thought to increase the efficacy of 5-FU against the tumor. To detect the OPRT protein by immunoblotting and/or immunohistochemical methods, we tried to prepare highly specific antibody against the peptide including human OPRT amino acid sequence. The anti-OPRT polyclonal antibody obtained by immunization of OPRT peptides to rabbits had high specificity for the OPRT protein in human tumor xenografts in immunoblot and immunohistochemical analysis. Furthermore, there was a positive correlation between the activity and proteins of OPRT (R2=0.632) in 12 human tumors. These results suggest that immunohistochemical detection of tumoral OPRT protein expression using our anti-OPRT antibody may provide useful methods to predict the clinical response to 5-FU-based chemotherapy.