CAP2 is a Valuable Biomarker for Diagnosis and Prognostic in Patients with Gastric Cancer

Cyclase-associated protein 2 (CAP2) protein is reported to be upregulated in hepatocellular carcinoma (HCC), human breast cancer, and malignant melanoma. However, its expression in gastric cancer remains unknown, this study was to investigate CAP2 expression and its prognostic significance in gastric cancer. Firstly, we analyzed the Oncomine databases to compare CAP2 mRNA expression in gastric cancer and normal tissues. CAP2 protein expression was analyzed in gastric cancer samples and non-tumor mucosa by RT-PCR and immunohistochemical analysis. Consequently, statistical analyses were performed to evaluate the clinicopathological significance of CAP2 expression in gastric cancer. CAP2 expression was significant higher in gastric cancer tissues than that in non-tumor mucosa at protein levels. CAP2 was up-regulated in 57.8% (252/436) of gastric cancer samples, while detected in only 10.9% (10/92) of non-tumor mucosa. Statistical analysis shows that the expression of CAP2 was correlated with tumor size, Lauren's classification, depth of invasion, lymph node and distant metastases, and regional lymph node stage, TNM stage, but not with age, sex, histology classification, and histologic differentiation. Kaplan-Meier analysis indicated that high CAP2 expression was associated with poor overall survival (78.7%) in 203 of 252 gastic cancer patients. In stage I, II, and III tumors, the 5-year survival rate was lower in those with high expression of CAP2 than those with low expression. In stage IV tumors, the expression of CAP2 did not correlate with the 5-year survival rate. Multiple Cox regression analysis indicated CAP2 as an independent predictor for overall survival [hazard ratio (HR) = 2.045, 95% confidence interval: 1.445-2.895, p < 0.01], while Lauren's classification, TNM stage, and expression of CAP2 were independent prognostic factors in patients with gastric cancer. For the first time, we found that CAP2 was upregulated in gastic cancer, and was associated with lymph node and distant metastases. CAP2 may serve as a prognostic indicator for patients with gastic cancer.