Apurinic/apyrimidinic endonuclease1/redox factor-1 (APE1/Ref-1) is a DNA repair enzyme whose expression is increased in several forms of cancerous cells. We investigated whether serum APE1/Ref-1 is elevated in patients with bladder cancer. Tumor tissue and serum from patients with bladder cancer who had not received chemotherapy or radiotherapy (n=51) and non-tumor healthy controls (n=55) was used. In immunohistochemistry, and immunoblot analysis, the APE1/Ref-1 protein level of bladder tissues was increased in patients with bladder cancer. The serum APE1/Ref-1 levels were significantly elevated in bladder cancer patients than in those of non-tumor healthy controls and its levels were correlated with tumor staging and grading. The ROC curve of APE1/Ref-1 showed an excellent area under the ROC curve of 0.824. In this study, the optimal combination of sensitivity and specificity were determined as 93% and 59% for a cut-off value of serum APE1/Ref-1 of 2.83 ng/100 μl, respectively. The serum APE1/Ref-1 levels are increased in patients with bladder cancer with recurrence. These data indicate serum APE1/Ref-1 may help to identify patients with bladder cancer and it can be used as a serological marker of bladder cancer.

Citation Format: Sunga Choi, Ju Hyun Shin, Yu Ran Lee, Myoung Soo Park, Chang Nam Yim, Young Gil Na, Jae Sung Lim, Byeong Hwa Jeon. APE1/Ref-1 as a serological biomarker for the detection of bladder cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 872. doi:10.1158/1538-7445.AM2014-872