Expression of CDCA8 correlates closely with FOXM1 in breast cancer: public microarray data analysis and immunohistochemical study.

Forkhead Box M1 (FOXM1) is an oncogenic transcription factor implicated in breast cancer progression and metastasis. However, the clinical significance of FOXM1 and its associated signaling genes in human breast cancer still needed to be clarified. In this study, we first analyzed the co-expression gene pattern of FOXM1 in three breast cancer gene expression microarray datasets from the Oncomine database. Cell division cycle associated 8 (CDCA8) gene was identified to correlate closely with FOXM1. In silico analysis further indicated that CDCA8 overexpressed in breast cancer tissues compared with the normal controls is significantly associated with the triple-negative phenotype. Experimentally, we performed a immunohistochemical study to detect the expression of CDCA8 in 112 breast cancer samples, and evaluated its clinicopathological and prognostic significance. We found that CDCA8 was frequently over-expressed in breast cancer tissues, and increased expression of CDCA8 was positively associated with FOXM1 expression, triple-negative phenotype and shorter overall survival. Moreover, we also found that combination of CDCA8 and FOXM1 showed a higher hazard ratio than the individual markers. Our results suggest that FOXM1-CDCA8 signature might be involved in breast cancer progression, and serves as a potential prognostic factor and a promising therapeutical target.