Clinical significance of sCIP2A levels in breast cancer.

OBJECTIVE: It has previously found that human oncoprotein cancerous inhibitor of protein phosphatase 2A (CIP2A) was overexpressed in breast cancer, and was positively correlated with lymph node metastasis of the patients. This study aimed to investigate the association between serum CIP2A and prognosis of breast cancer. Then, we investigated whether CIP2A could be as a therapeutic target in breast cancer treatment.

PATIENTS AND METHODS: Preoperative CIP2A levels of 240 patients with breast cancer and 480 cases of controls were measured by ELISA method. The association of CIP2A levels with clinicopathological outcomes was investigated by univariate and multivariate analyses. The effect of CIP2A on breast cancer MDA-MB-231 cells was evaluated by CIP2A siRNA-mediated depletion of the CIP2A protein followed by an analysis of cell proliferation, invasion, colony growth, and xenograft growth and metastasis.

RESULTS: The serum CIP2A levels in patients with breast cancer were (79.0 ± 74.2) ng/mL, which was significantly higher than that in those controls (25.6 ± 21.4) ng/mL for male and (24.8 ± 20.6) ng/mL for female control. Higher preoperative CIP2A levels were significantly associated with the American Joint Committee on Cancer (AJCC) stage, histological grade and lymph node metastasis. Patients with elevated CIP2A levels showed worse survival. In multivariate analysis, elevated preoperative CIP2A levels were independent prognostic factors. Patients with high CIP2A levels had significantly shorter overall survival (OS) and disease-free survival (DFS) times. Knockdown of CIP2A by stable CIP2A siRNA transfection inhibited MDA-MB-231 cell proliferation, invasion, colony growth in vitro, and xenograft growth and metastasis in vivo.

CONCLUSIONS: Our results suggest that serum CIP2A is significantly higher in patients with breast cancer, which is a potential biomarker to make a distinction between breast cancer patients and healthy controls. Higher serum CIP2A levels positively associated with the aggressive phenotype of breast cancer, and forecasts poor prognosis for patients with breast cancer. Knockdown of CIP2A may be a novel target for prevention and treatment of breast cancer.