Breast cancer is a heterogeneous disease that exists in multiple subtypes, some of which still lack targeted and effective therapy. A major challenge is to unravel their underlying molecular mechanisms and bring to light novel therapeutic targets. In this study, we investigated the role of WNT-inducible signaling pathway protein 1 (WISP1) matricellular protein in the acquirement of an invasive phenotype by breast cancer cells. To this aim, we treated non-invasive MCF7 cells with WISP1 and assessed the expression levels of macrophage migration inhibitory factor (MIF) and its cellular receptor CD74. Next, we examined the expression of epithelial-to-mesenchymal transition (EMT) markers as well as molecular effectors of the tumor microenvironment, such as CD44, the main hyaluronan receptor that also acts as a co-receptor for MIF, the hyaluronan oncogenic network, and specific matrix metalloproteinases (MMPs) and their endogenous inhibitors, tissue inhibitors of metalloproteinases (TIMPs). The results showed that WISP1 potently induces the expression of MIF cytokine and affects the expression of specific extracellular matrix molecules with established roles in the promotion of malignant properties. Notably, Src kinases and MIF are critically involved in these processes. Collectively, the present study demonstrates for first time a WISP1/Src/MIF axis as well as its ability to induce an invasive phenotype in MCF7 cells and highlights novel cellular and molecular processes involved in the epithelial-to-mesenchymal transition and the development of invasive breast cancer. This suggests that specific cues from the tumor microenvironment can activate a migratory/invasive phenotype in a subpopulation of cells residing within the heterogeneous breast tumor.
Christopoulou et al. (Thu,) studied this question.