High Eg5 expression predicts poor prognosis in breast cancer

Eg5 is a motor protein belonging to the kinesin-5 family and has been suggested to exert important function in tumors. In this study, we determined the mRNA and protein expression levels of Eg5 in cancerous and non-cancerous breast tissue by quantitative real-time polymerase chain reaction (qRT-PCR) and tissue microarray immunohistochemistry analysis (TMA-IHC) respectively. The results of 20 fresh-frozen BC samples demonstrated that Eg5 mRNA levels were significantly higher in BC tissues compared with corresponding non-cancerous tissue (p = 0.0009). TMA-IHC analysis in 127 BC tissues revealed that Eg5 expression obviously correlated with clinicopathologial parameters, including tumor grade (p = 0.004), ER status (p = 0.030), Ki67 status (p = 0.005), molecular classification (p = 0.026), N stage (p = 0.015), and TNM stage (p = 0.001). Kaplan-Meier survival curve indicated that high Eg5 expression (p = 0.012), Ki67 status (p = 0.014) and TNM stage (p = 0.026) were independent factors to predict poor prognosis for patients with breast cancer. Our data suggest that Eg5 is not only overexpressed in BC, it may be also served as a potential prognostic marker.