Cancer is one of the most complex and challenging pathologies to treat. Among the different types, breast cancer has been one of the most diagnosed cancers. Within the subtypes, triple negative breast cancer (TNBC) has shown to be the most aggressive with the poorest prognosis. Hence, there is an urgent need for other approaches to treat TNBC. In this context, in tissues from TNBC patients, the expression of Macrophage migration inhibitory factor (MIF) has been shown to be significantly elevated compared to healthy tissues. MIF is a cytokine/chemokine associated with various malignancies, exhibiting pleiotropic functions that could promote the establishment and progression of cancer. For instance, it has pro-inflammatory, pro-angiogenic, anti-apoptotic, and proliferative functions, among others. Moreover, high MIF levels within the TME or the serum have been directly associated with cancer progression in patients. Conversely, knocking out or downregulation of MIF has been shown to reduce tumor progression in different cancer models, including TNBC. Nonetheless, up to now, the contribution of cancer cell- vs. stromal cell-derived MIF in TNBC has not been determined. In this regard, we conducted in-vivo experiments whereby MIF-Floxed (FL) and MIF-deficient (MIF-/-) mice were injected with E0771, a murine TNBC cancer cell line. Our results highlight the importance of stromal cell-derived MIF in tumor progression. This was evidenced by the fact that MIF-/- mice exhibited smaller tumors compared to the control group, which correlated with reduced percentages of cancer cells, more activated CD8+ T cells, and more effector T cells. Additionally, we found that cancer cells were an important source of MIF, as tumor-bearing MIF-/- mice had higher levels of MIF in the serum compared to naïve MIF-/- mice. To determine the contribution of cancer cell-derived MIF, E0771 was genetically modified using CRISPR/Cas9 technology to generate a MIF-deficient cell line. Unfortunately, the generation of E0771 MIF deficient cells was not successful. Additionally, to provide evidence that extracellular cancer cell-derived MIF plays an important role in cancer cell proliferation/survival, we used nanobodies in an in-vitro setting as a novel tool to block MIF. We determined that when extracellular MIF is blocked, there is a higher level of cell death, thus providing evidence that secreted MIF is important for cancer cell survival. Collectively, our results establish the importance of both stromal- and cancer cell-derived MIF in TNBC and provide evidence that blocking of extracellular MIF using Nbs negatively affects E0771 survival. Hence, these results set the basis to pave the way to validate the anti-MIF Nbs in vivo as a novel intervention strategy, either alone or combined with currently used strategies to treat TNBC.
Unravelling the contribution of cancer cell- and stromal cell- derived MIF in solid tumor progression: Het ontrafelen van de bijdrage van van kankercellen en stromale cellen afgeleide MIF in de progressie van solide tumoren
Mora Barthelmess, R. ((PhD) Student), Stijlemans, B. (Co-promotor). 22 jun 2021
Scriptie/Masterproef: Master's Thesis