Visfatin Enhances Breast Cancer Progression through CXCL1 Induction in Tumor-Associated Macrophages

SIMPLE SUMMARY: Visfatin is an adipocytokine highly expressed in breast tumor tissues and circulation, and is positively associated with breast cancer progression and poorer clinical prognosis. In this study, we explored the role of adipocytokine in the breast tumor microenvironment with the focus on the interactions between visfatin and macrophages in breast cancer development by using in vitro, in vivo, and clinical studies. Visfatin promoted M2 differentiation in monocytic cells through ERK/CXCL1 induction and enhanced breast cancer cell viability, migration, tumorsphere formation, EMT, and stemness. Our study adds new insights to the growing body of evidence supporting the role of tumor-stromal interactions in breast cancer and also provides a potential therapeutic target. ABSTRACT: Visfatin, an adipocytokine highly expressed in breast tumor tissues, is associated with breast cancer progression. Recent studies showed that adipocytokines mediate tumor development through adipocytokine tumor-stromal interactions in the tumor microenvironment. This study focused on the interaction between one key stromal constituent—tumor-associated macrophages—and visfatin. Pretreatment of THP-1 and peripheral blood mononuclear cells (PBMCs) with recombinant visfatin resulted in M2-polarization determined by CD163 and CD206 expression. Indirect co-culture with visfatin-treated THP-1 (V-THP-1) promoted the viability, migration, tumorsphere formation, EMT, and stemness of breast cancer cells. Cytokine array identified an increased CXCL1 secretion in V-THP-1 conditioned medium and recombinant CXCL1 enhanced cell migration and invasion, which were abrogated by the CXCL1-neutralizing antibody. Additionally, visfatin induced pERK in THP-1 cells and clinical samples confirmed a positive CXCL1/pERK correlation. In an orthotopic mouse model, the tumor bioluminescent signal of luciferase-expressing MDA-MB-231 (Luc-MDA-MB-231) cells co-cultured with V-THP-1 and the expression of proliferation marker Ki67 were significantly higher than that co-cultured with THP-1. Furthermore, tail vein-injected Luc-MDA-MB-231 pretreated with V-PBMCs conditioned medium metastasized to lungs more frequently compared to control, and this was reversed by CXCL1 blocking antibody. In summary, this study demonstrated that visfatin enhanced breast cancer progression via pERK/CXCL1 induction in macrophages.