Inhibitory Impact of the Amino Benzoic Derivative DAB-2-28 on the Process of Epithelial-Mesenchymal Transition in Human Breast Cancer Cells

Macrophage-mediated inflammation is proposed to be involved in the epithelial-mesenchymal transition (EMT) of different types of cancers. This makes macrophage-derived inflammatory factors a prime target for developing new treatments. This study aims to demonstrate the therapeutic potential and mechanism of action of DAB-2-28, a novel small molecule derived from aminobenzoic acid, in the treatment of breast cancer. The luminal MCF-7 and the triple-negative MDA-MB-231 cancer cell lines used in this study represent, respectively, a breast cancer whose differentiation state is related to the epithelial phenotype of the mammary gland, and a breast cancer expressing a highly aggressive mesenchymal phenotype. In MCF-7 cells, soluble factors from macrophage-conditioned media (MØ-CM) induce a characteristic morphology of mesenchymal cells with an increase in the expression of Snail1, a mesenchymal marker, opposed to a decrease in the expression of E-cadherin, an epithelial marker. Although our studies demonstrated that DAB-2-28 does not affect the differential expression of Snail1 and E-cadherin, DAB-2-28 negatively regulates the different responses of MCF-7 cells to MØ-CM by decreasing a) clonogenic growth; b) invasion and migration capacities; c) MMP9 expression and gelatinase activity; and d) NFkB, STAT3, AKT, and SMAD2 protein phosphorylation. Moreover, differential expression of Snail1 and E-cadherin in MCF-7 cells was also induced by the cytokines TNFa and TGFb1, alone or in combination, and the StemXvivo® EMT Inducing Media reagent. DAB-2-28 affects the response of MCF-7 cells to these various EMT inducers by inhibiting the phosphorylation of NFkB, SMAD2 and/or CREB proteins. Finally, DAB-2-28 also decreases the macrophage- and cytokine-induced invasion and migration capacities of MDA-MB-231 cells, probably via an inhibition of MMP9 activity and the phosphorylation of NFkB, STAT3, AKT, SMAD2, and CREB proteins. We propose that the ability of DAB-2-28 to prevent cancer cells from acquiring EMT-related protumor properties could be exploited in a clinical setting to block disease progression to a metastatic form and thus improve the survival rate of breast cancer patients.