Overexpression of carboxypeptidase A4 (CPA4) is associated with poor prognosis in patients with gastric cancer.

CarboxypeptidaseA4 (CPA4) is a zinc-containing exopeptidases, and its aberrant expression has been implicated in cancer development and progression. However, few studies have investigated the association between CPA4 over-expression and clinical significance in gastric cancer (GC). In this study, we employed immunohistochemistry to evaluate the expression of CPA4 in gastric cancer tissues, and found that elevated CPA4 expression was detected in 64% (n=100) of primary GCs, but was weak or no staining in the normal mucosa. Clinical relevance analysis showed that positive staining for CPA4 was significantly associated with Tumor size, Stage, Lymph node metastasis, Depth of invasion and Distant metastasis. As tumor markers p53 and Ki67 are closely associated with tumor progression, we further analyzed the correlations between CPA4 levels and these two factors. We found that abnormal expression of CPA4 was positively associated with Ki67 (P=0.002) and reversely correlated with p53 (P=0.035) in GC. In Kaplan-Meier survival analysis, high levels of CPA4 were significantly associated with unfavorable survival in GC patients (P<0.001). Multivariate Cox regression model showed that high expression of CPA4 was an independent prognostic factor for GC patients. In conclusion, our results suggested that CPA4 was highly expressed in gastric cancer tissues. Overexpression of CPA4 can be used as an independent poor prognostic factor in gastric cancer.