Overexpression of SGLT1 is correlated with tumor development and poor prognosis of ovarian carcinoma

Abstract

Overexpression of glucose transporters has been identified in a variety of human cancers. However, the expression status of Sodium dependent Glucose Transporter 1 (SGLT1) in ovarian carcinoma has not been investigated. In our study, protein expression levels of SGLT1 were explored by semiquantitative immunohistochemical staining on archival formalin-fixed paraffin-embedded pathologic specimen consisting of 178 epithelial ovarian tumors. Receiver operating characteristic curve analysis, Spearman's rank correlation, Kaplan-Meier plots and Cox proportional hazards regression model were utilized to analyze the data. The threshold for high expression of SGLT1 was determined to be above 40% (areas under curve = 0.683, P = 0.003) based on the area under curves. Significantly overexpression of SGLT1 was observed in 39.7% invasive carcinomas, 11.5% borderline tumors, 10% cystadenomas but in none of the normal ovaries (0%). In ovarian carcinomas, SGLT1 overexpression was positively correlated with later pT status (P = 0.029) and advanced FIGO stage (P = 0.024). By univariate survival analysis on the ovarian carcinoma cohorts, overexpression of SGLT1 was associated with shortened patient survival (mean 70.5 months in tumors with overexpression of SGLT1 versus 89.3 months in tumors with normal levels of SGLT1; P = 0.019). By multivariate analysis, SGLT1 protein expression remained as a significant and independent prognostic factor for the prediction of patient survival (P = 0.033). SGLT1 overexpression, as examined by immunohistochemistry, is an independent biomarker for poor prognosis of patients with ovarian carcinoma.