Clusterin is a biomarker of breast cancer prognosis and correlated with immune microenvironment

Background: It has been established that clusterin is involved in the invasion of immune cells in the tumor microenvironment, but it remains unknown how it promotes immune invasion in breast cancer. Methods: We used Tumor Immune Estimation Resource (TIMER) and Gene Expression Profiling Interactive Analysis (GEPIA) databases to assess the relation between expression of clusterin and immunoinfiltration-related marker genes. TIMER database was used to evaluate the expression of clusterin, and its relation to tumor immune invasion was examined. Based on Kaplan-Meier plotter database, we investigated the association between clusterin expression and prognosis in patients with cancer, and the impact of clinicopathological factors and cancer-related outcomes. Results: Clusterin expression was markedly associated with prognosis of a variety of tumors, specifically breast cancer. Enhanced clusterin expression was markedly associated with molecular typing of breast cancer and expression of multiple markers related to specific immune cell subsets. Conclusions: These results indicate that clusterin is connected to prognosis of breast cancer patients and tumor immune cell infiltration. This demonstrates that clusterin may be a biomarker of immune cell recruitment into breast tumors and an important biomarker for immune cell infiltration; consequently being a valuable prognostic factor in breast cancer patients.