PIGR predicts good clinical outcomes and plays a tumor suppressor role in the development of breast cancer via enhancing tumor immunity

Abstract Background : Breast cancer (BRCA) is a phenotypically and functionally heterogeneous disease. It is necessary to discover new biomarkers or therapeutic targets to improve treatment effects. Polymeric immunoglobulin receptor (PIGR) plays an anti-cancer role in a variety of human malignancies. This study aimed to explore the prognostic significance and possible functional mechanism of PIGR in BRCA tissues. Methods : We examined the expression level of PIGR in BRCA and normal breast tissues. Effects of PIGR on the proliferation, clone formation, and migration of BRCA cells were explored. We used logistic regression analysis to test the correlation between PIGR expression and clinicopathological characteristics of BRCA patients. The prognostic significance of PIGR in BRCA was investigated via the Kaplan-Meier survival analysis and multivariate Cox analysis. The GSEA method was used to discover the biological processes and pathways of PIGR co-expression genes enriched. Results : The expression level of PIGR was down-regulated in BRCA tissues. CCK-8 proliferation and colony formation assay demonstrated that PIGR could not affect BRCA cell proliferation and clone formation but could increase migration. The GSEA revealed PIGR co-expression genes joined mainly in the immune response. The expression level of PIGR significantly correlated to the infiltration of immune cells and the abundance of immune-related molecules. Conclusions : PIGR was an independent protective factor for BRCA patients’ prognosis. PIGR correlated with tumor immunity and exerted antitumor effects in BRCA. PIGR might be a novel prognostic biomarker and therapeutic target.