Diagnostic value and significance of serum APE1 in colorectal cancer

Abstract

Objective To investigate the expression of serum apurinic/apyrimidinic endonuclease 1 (APE1) in colorectal cancer and its diagnostic value. Methods A total of 202 patients with identified colorectal cancer admitted in our center from January 2010 to September 2015 were recruited in this study, and another 242 healthy volunteers who took physical examination at the same period served as normal control. Their serum APE1 level was quantified by ELISA. The expression of APE1 protein in colorectal cancer tissues was detected by immunohistochemistry. The expression of carcinoembryonic antigen (CEA) was detected by C-12 tumor protein chip kit. The correlations of APE1 protein levels in the serum and tumor tissues with age, gender, clinical stage and other indicators were analyzed. Receiver operating characteristic (ROC) curve was plotted to evaluate the value of serum APE1 and CEA levels in the diagnosis of colorectal cancer. Results The serum APE1 level was 0.331 (0.007~4.359) ng/mL in the colorectal cancer patients, which was significantly higher than that in healthy control [0.091(0～1.374) ng/mL, P < 0.001]. Spearman correlation analysis showed that the serum APE1 level was positively correlated with its protein expression in colorectal cancer tissues (r=0.331, P=0.025), but had no relations with age, sex and clinical stages. ROC curve displayed that the area under the curve (AUC) was 0.799 (95%CI=0.756~0.843), the sensitivity was 76.20%, and the specificity was 76.40% for serum APE1 level in the diagnosis. While, the AUC value was 0.736 (95%CI=0.687~0.785), the sensitivity was 51.00%, and the specificity was 99.60% for serum CEA level. Their combination increased the AUC value to 0.857 (95%CI=0.819~0.896), and the sensitivity and accuracy to 72.30% and 91.30%, respectively. Conclusion The serum APE1 level is positively correlated with its expression level in the colorectal cancer tissue, and both are significantly higher than those in the health control. Combined detection of serum APE1 and CEA levels might be considered as serum markers in auxiliary diagnosis for colorectal cancer.

Keywords

• apurinic/apyrimidinic endonuclease 1
• colorectal cancer
• tumor biomarker
• diagnosis