Upregulation of cyclase-associated actin cytoskeleton regulatory protein 2 in epithelial ovarian cancer correlates with aggressive histologic types and worse outcomes

Objective: Cyclase-associated actin cytoskeleton regulatory protein 2 (CAP2) regulates actin dynamics to control cell cycles and cell migration. CAP2 overexpression contributes to cancer progression in several tumor types; however, the role of CAP2 expression in ovarian cancer remains unclear. This study aimed to clarify the significance of CAP2 expression in epithelial ovarian tumor. Methods: We evaluated CAP2 expression in ovarian cancer cell lines using quantitative real-time polymerase chain reaction, western blotting and immunocytochemistry and examined the effect of CAP2 silencing in migration and proliferation assays. CAP2 immunohistochemistry was conducted using tissue specimens from 432 ovarian carcinoma patients; a further 55 borderline and benign 65 lesions were analyzed. CAP2 expression levels were defined as low, intermediate or high, for correlation analysis with clinicopathological factors. Results: CAP2 expression was significantly higher in cell lines from Type II ovarian cancer than in those in Type I, and knockdown of CAP2 showed decreased migration and proliferation. Higher levels of CAP2 expression in human tissues were associated with Type II histology, residual lesion, lymph node metastasis, ascites cytology and higher clinical stage. High CAP2 expression levels were observed in 26 (23.4%) of 111 Type II ovarian cancers and in 16 (5.0%) of 321 Type I cancers but not in any borderline or benign lesions. Multivariate analyses showed that CAP2 expression in ovarian cancer is an independent prognostic factor for recurrence-free survival (P = 0.019). Conclusion: CAP2 expression is upregulated in aggressive histologic types of epithelial ovarian cancer and serves as a novel prognostic biomarker for patient survival.