CXCL13 inhibition induce the apoptosis of MDA-MB-231 breast cancer cells through blocking CXCR5/ERK signaling pathway

OBJECTIVE: Treatment of the high-risk triple negative breast cancer (TNBC) is a critical clinical challenge. Here we aimed to explore a novel strategy for TNBC treatment by blocking the tumor-associated chemokine CXCL13 in the MDA-MB-231 TNBC cells. MATERIALS AND METHODS: MDA-MB-231 cells were treated with anti-CXCL13 antibodies (inhibition group), or phosphate-buffered saline (PBS) (control group), followed by determining the levels of interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor beta-1 (TGF-beta 1) with enzyme-linked immunosorbent assay (ELISA). The effects of CXCL13 inhibition on cell proliferation and apoptosis were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry, respectively. Quantitative Real Time-PCR (qRT-PCR) and Western blot were used to compare the levels of CXCL13, CXCR5, extracellular signal-regulated kinase (ERK). The levels of cyclin D1 and cleaved caspase-9 were detected by Western blot. RESULTS: The levels of IL-1, TNF-alpha and TGF-beta 1 in MDA-MB-231 cells treated with anti-CXCL13 antibodies were significantly downregulated (p<0.05). Meanwhile, CXCL13 blockade decreased the cell proliferation and increased the apoptosis rate of MDA-MB-231 cells. The inhibition of CXCL13 led to marked reduction in CXCL13 and CXCR5 mRNA and an increase in ERK mRNA. The inhibition of CXCL13 resulted in the downregulation of CXCL13, CXCR5, p-ERK/ERK, cyclin D1 and upregulation of cleaved caspase-9 proteins. CONCLUSIONS: CXCL13 blockade effectively suppressed the proliferation of MDA-MB-231 cells by promoting cell apoptosis. This effect is presumably associated with the downregulation of CXCL13 and suppression of the CXCR5/ERK signaling pathway.