CXCL13 expression in mouse 4T1 breast cancer microenvironment elicits anti-tumor immune response by regulating immune cell infiltration
Abstract Breast cancer is the most commonly diagnosed cancer type and the leading cause of cancer-related deaths among women worldwide. Previous studies have reported contradictory performance of chemokine CXC motif ligand 13 (CXCL13) in breast cancer. In this study, TCGA database analysis revealed that CXCL13 was overexpressed in various human cancers including breast carcinoma, and associated with good clinical prognosis in breast cancer. Flow cytometry detection also found up-regulated intracellular CXCL13 expression in human breast cancer cell lines. To explore the possible role of CXCL13 in breast cancer microenvironment, mouse triple negative breast cancer (TNBC) was lentivirally transfected to stably overexpress mouse CXCL13 (4T1-CXCL13). Both parental 4T1 and 4T1-CXCL13 strains showed no in vitro and in vivo endogenous cell surface CXCR5 expression. In immune-competent BALB/c mice, the in vivo tumor growth of 4T1-CXCL13 was significantly inhibited and even completely eradicated, accompanied with increased infiltrations of CD4+, CD8 + T lymphocytes and CD11b + CD11c + DCs. Further investigations showed that CXCL13 expression in 4T1 tumor microenvironment elicited long-term anti-tumor immune memory, and rejection of distal parental tumor. The anti-tumor activity of CXCL13 was remarkedly impaired in BALB/cA-nu nude mice, or in BALB/c mice with CD8 + T lymphocyte or NK cell depletion. Our investigation indicated that CXCL13 expression in TNBC triggered effective anti-tumor immunity by chemoattracting immune cell infiltrations, and could be considered as a novel prognostic marker for TNBC.