Girdin protein expression is associated with poor prognosis in patients with invasive breast cancer.

Girdin is an actin-binding Akt substrate that is an integral component of the PI3K/Akt signalling pathway. However, the clinicopathological significance of Girdin expression in breast cancer has not been clarified. The purpose of this study was to characterise the clinicopathological implication of Girdin expression in breast cancer. Immunohistochemistry-based protein expression analyses of 892 human breast cancer tissues showed that Girdin was expressed in 289 (32.4%) cases. Girdin expression was significantly associated with larger tumour size, frequent lymph node invasion, advanced cancer stage, and expression of oestrogen and progesterone receptors. Patients who had breast cancer with Girdin expression experienced significantly poorer overall survival (OS) (p=0.021) and disease-free survival (DFS) (p=0.002) than those without Girdin expression. In subtype analyses, Girdin expression was significantly correlated with poorer OS and DFS in HER2 subtype (p=0.004 and p=0.034, respectively). In triple negative breast cancer (TNBC) subtype, Girdin expression was significantly correlated with poorer DFS (p=0.035), and there was a trend toward poorer OS (p=0.060) in TNBC patients with Girdin expression. Multivariate analysis revealed that Girdin expression was an independent prognostic factor for OS (p=0.022) and DFS (p=0.030) in patients with breast cancer. In HER2 subtype under multivariate analysis, Girdin expression retained its role as an independent prognostic predictor for worse OS (p=0.023), and there was a trend toward poorer DFS (p=0.086) in patients with HER2 subtype expressing Girdin. Girdin expression may serve as a useful prognostic factor for invasive breast cancer, especially for the HER2 subtype.