Bisphenol A promotes the invasive and metastatic potential of ductal carcinoma in situ and pro-tumorigenic polarization of macrophages.

Abstract

Increased cancer risk and immune disorders linked with exposure to environmental endocrine disruptors like bisphenol A (BPA) have been steadily reported. Nevertheless, the impacts of BPA on the breast ductal carcinoma in situ (DCIS) progression and macrophage polarization remain to be elucidated. Here, we analyzed the differentially expressed genes in BPA-exposed DCIS cells and explored BPA effects on DCIS progression and macrophage polarization in vitro and in vivo. 291 genes were differentially expressed in 10-8 M BPA-exposed DCIS cells, in which the gene ontology terms of biological processes associated with negative regulation of cell death, cell adhesion and immune response was enriched. 10-8 M BPA promoted the proliferation and migration of DCIS cells and the migration of macrophages, and upregulated the expression of M1 (NOS2) or M2 markers (Arg-1 and CD206) in macrophages. In co-culture system, the migratory capacity of both cells and the expression levels of NOS2, Arg-1 and CD206 in macrophages were significantly enhanced upon 10-8 M BPA. In a DCIS xenograft model, oral exposure to an environmentally human-relevant low dose of 2.5 µg/L BPA for 70 days via drinking water led to an ∼2-fold promotion in the primary tumor growth rate and a significant enhancement of lymph node metastasis along with increased pro-tumorigenic CD206+ M2 polarization of macrophages. These results demonstrate that BPA acts as an accelerator to promote DCIS progression to invasive breast cancer by affecting DCIS cell proliferation and migration as well macrophage polarization toward a pro-tumorigenic phenotype.