Upregulated Nuclear Y-box Binding Protein-1 Expression is Closely Associated with Mammalian Target of Rapamycin Expression in Endometrial Cancer.

Enhanced oncogenic Y-box binding protein-1 (YB-1) expression, associated with the aberrant expression of genes involved in cell proliferation, survival, and drug resistance, can predict prognostic outcomes in patients with various malignancies. We examined whether YB-1 could predict prognostic outcomes in patients with endometrial cancer and whether enhanced YB-1 expression affects the expression of mammalian target of rapamycin (mTOR) in endometrial cancer. We examined the expression levels of YB-1 and mTOR in tumor samples of 166 patients with endometrial cancer, including those with endometrioid grade 1-3, serous carcinoma, and stage I-IV disease, who underwent surgery. The expression levels of both molecules were assessed using immunohistochemical analysis. The correlation between the expression levels of YB-1 or mTOR and prognosis was also confirmed.The positivity rate of nuclear YB-1 expression was 9.4%. YB-1 expression was associated with poor progression-free survival (P = 0.012) and overall survival (P = 0.003). Fifty-nine patients (35.5%) exhibited mTOR expression. Nuclear YB-1 expression was also correlated with mTOR expression (P = 0.006). We observed similar results when examining only patients who underwent adjuvant chemotherapy. Enhanced nuclear YB-1 expression could predict poor outcomes in endometrial cancer and was significantly associated with enhanced mTOR expression.