Expression of Y-Box-binding protein 1 in Chinese patients with breast cancer

The purpose of this study was to investigate the expression of Y-Box-binding protein 1 (YB-1) in breast cancer and its correlation with clinicopathological characteristics and prognosis. Paraffin sections were retrospectively collected from 239 cases of stage I-III breast cancer patients and 30 healthy females who received surgery between January 2000 and December 2004 in the Chinese People's Liberation Army General Hospital. The protein expression of YB-1 was detected by immunohistochemistry. The expression difference between the two groups and the correlation between YB-1 expression and clinicopathological characteristics and breast cancer prognosis were analyzed. Within the breast cancer group, YB-1 was expressed in the cytoplasm in 100.0% (239/239) of cases and in the nucleus in 36.8% (88/239) of cases. Within the control group of normal breast tissue, YB-1 was expressed in the cytoplasm in 100.0% (30/30) of cases and in the nucleus in 16.7% (5/30) of cases. The expression of YB-1 in the nucleus of breast cancer cells was significantly higher than that in normal breast tissue (P = 0.029). The expression of YB-1 in the nucleus of breast cancer cells positively correlated with the Scarff-Bloom-Richardson grade (P = 0.007) and HER-2 expression (P = 0.005), negatively correlated with ER expression (P = 0.004), and was independent of the age, menstrual status, pathological type, tumor size, lymph node status, presence of thrombosis, PR expression, and EGFR expression. The 5-year disease-free survival (DFS) and overall survival (OS) of patients with positive YB-1 expression in the nucleus were significantly lower than those of patients who were negative for nuclear YB-1 expression, and the difference was statistically significant (DFS 65.9% vs. 82.1%, P = 0.000; OS 79.5% vs. 92.1%, P = 0.000). Multivariate analysis suggested that the expression of YB-1 in the nucleus is an independent prognostic factor that affects DFS and OS in breast cancer patients (DFS P = 0.015; OS P = 0.035). In conclusion, the expression of YB-1 in the nucleus is related to carcinogenesis and the development of breast cancer. Therefore, YB-1 is an important molecular marker that can be used to predict breast cancer prognosis.