Prognostic value of gamma‐interferon‐inducible lysosomal thiol reductase expression in female patients diagnosed with breast cancer

Abstract Because of the high heterogeneity of breast cancer outcome, identification of novel prognostic biomarkers is critical to improve patient stratification and guide precise treatment. We examined the prognostic value of gamma‐interferon‐inducible lysosomal thiol reductase (GILT) expression in a training set of 416 breast cancer patients and a validation set of 210 patients, and performed functional studies to investigate the functions and underlying mechanisms of GILT on breast cancer prognosis. Our results indicated that high GILT expression in breast cancer cells was associated with improved disease‐free survival (DFS; hazard ratio [HR] = 0.189, 95% confidence interval [CI]: 0.099‐0.361) and breast cancer‐specific survival (BCSS; HR = 0.187, 95% CI: 0.080‐0.437) of breast cancer patients both in the training set and the external validation set (HR = 0.453, 95% CI: 0.235‐0.873 for DFS, HR = 0.488, 95% CI: 0.245‐0.970 for BCSS). In vitro and in vivo studies showed that GILT overexpression inhibited breast cancer cells proliferation, invasion, migration and tumor formation in nude mice and increased sensitivity of breast cancer cells to standard treatment. Proteomics analysis indicated that GILT inhibited reactive oxygen species (ROS) and autophagy activation in breast cancer cells, and GILT overexpression‐mediated tumor growth was further enhanced in the presence of autophagy or ROS inhibitors. Our results demonstrate that GILT expression can be effectively used to predict the prognosis and guide treatment strategies of breast cancer patients.