Background: The second intron of Mitogen-Activated Protein Kinase Kinase 4 (MAP2K4), an important hub in the pro-invasive MAPK pathway, harbors miR-744. There is accumulating evidence that intronic micro-RNAs (miRNAs) are capable of either supporting or restraining functional pathways of their host genes, thereby creating intricate regulative networks. We thus hypothesized that miR-744 regulates glioma migration by interacting with its host’s pathways. Methods: Patients’ tumor specimens were obtained stereotactically. MiR-744 was overexpressed in U87, T98G, and primary glioblastoma (GBM) cell lines. Cell mobility was studied using migration and Boyden chamber assays. Protein and mRNA expression was quantified by SDS-PAGE and qRT-PCR. Interactions of miR-744 and 3’UTRs were analyzed by luciferase reporter assays, and SMAD2/3, p38, and beta-Catenin activities by TOP/FOPflash reporter gene assays. Results: As compared to a normal brain, miR-744 levels were dramatically decreased in GBM samples and in primary GBM cell lines. Astrocytoma WHO grade II/III exhibited intermediate expression levels. Re-expression of miR-744 in U87, T98G, and primary GBM cell lines induced focal growth and impaired cell mobility. Luciferase activity of 3’UTR reporter constructs revealed the pro-invasive factors TGFB1 and DVL2 as direct targets of miR-744. Re-expression of miR-744 reduced levels of TGFB1, DVL2, and the host MAP2K4, and mitigated activity of TGFB1 and DVL2 downstream targets SMAD2/3 and beta-Catenin. TGFB1 knock-down repressed MAP2K4 expression. Conclusion: MiR-744 acts as an intrinsic brake on its host. It impedes MAP2K4 functional pathways through simultaneously targeting SMAD-, beta-Catenin, and MAPK signaling networks, thereby strongly mitigating pro-migratory effects of MAP2K4. MiR-744 is strongly repressed in glioma, and its re-expression might attenuate tumor invasiveness.

Background: The recombinant IL-1 receptor antagonist anakinra—currently approved for the treatment of autoinflammatory diseases—blocks IL-1β-mediated inflammatory signaling. As inflammation is a major driver of cancer, we hypothesized that anakinra might be able to mitigate glioblastoma (GBM) aggressiveness. Methods: Primary GBM or T98G cells were incubated alone or with peripheral blood mononuclear cells (PBMCs) and were subsequently treated with IL-1β and/or anakinra. T cells were obtained by magnetic bead isolation. Protein and mRNA expression were quantified by SDS-PAGE, qRT-PCR, and ELISA, respectively. Cell proliferation and apoptosis were analyzed via flow cytometry. Chemotaxis was studied via time-lapse microscopy. Results: Upon IL-1β stimulation, anakinra attenuated proinflammatory gene expression in both GBM cells and PBMCs, and mitigated tumor migration and proliferation. In a more lifelike model replacing IL-1β stimulation by GBM–PBMC co-culture, sole presence of PBMCs proved sufficient to induce a proinflammatory phenotype in GBM cells with enhanced proliferation and migration rates and attenuated apoptosis. Anakinra antagonized these pro-tumorigenic effects and, moreover, reduced inflammatory signaling in T cells without compromising anti-tumor effector molecules. Conclusion: By dampening the inflammatory crosstalk between GBM and immune cells, anakinra mitigated GBM aggressiveness. Hence, counteracting IL-1β-mediated inflammation might be a promising strategy to pursue.