P18.13.A TOWARDS MOTILITY TRAPPING TO REDIRECT HIGH-GRADE GLIOMA MIGRATION: DIFFERENTIAL CHEMOTACTIC RESPONSES TO CCL2, CXCL10 AND CXCL12 IN DIFFUSE MIDLINE GLIOMA

Abstract BACKGROUND High-grade gliomas (HGG) are highly migratory tumors, leading to therapy failure and a dire prognosis. HGG migration is guided by chemotaxis, with chemokines in the tumor micro-environment acting as migratory signals. Based on this principle, we aim to evaluate the efficacy of a novel therapeutic strategy, called motility trapping. It uses chemotactic signals to redirect disseminated HGG cells to defined locations (e.g. back to the resection margin), where they are targeted by local therapy. Previous studies mainly focused on glioblastoma (GB) with regard to chemoattraction. Therefore, this work evaluated the migration of H3K27-altered diffuse midline glioma (DMG) in response to three chemoattractants, which have shown to attract GB cells in literature. It is part of a larger project that will compare chemotactic behavior across HGG subtypes. MATERIAL AND METHODS The migratory response of the primary H3K27-altered DMG cell line HSJD-DIPG-007 to CCL2, CXCL10 and CXCL12 was assessed in vitro using the agarose drop assay. Drops were loaded with the respective chemokines at concentrations ranging from 25 nM to 500 nM, or PBS (control). Migration was evaluated by counting the number of cells that invaded the drops at 6 and 48 hours using brightfield microscopy. Statistical analysis was performed using the Mann-Whitney U test. Evaluation of more cell lines and chemoattractants is ongoing. RESULTS After 6 hours, 200 nM CXCL12 induced the strongest response and led to a 123% increase in tumor cell migration compared to control condition (p=0.01, n=6), but this difference was no longer observed at 48 hours (p=0.86, n=5). Increasing the CXCL12 concentration to 500 nM resulted in fewer migrated cells at 6 hours and showed no significant difference compared to the control drops at 48 hours (p=0.30, n=6). In contrast, 500 nM CCL2 produced the largest increase in tumor cell migration at 48 hours, with a 104% rise compared to control (p=0.02, n=5), but showed no significant effect at 6 hours. CXCL10 did not significantly affect tumor cell migration at either time point across the tested concentrations. CONCLUSION Our data demonstrates directional migration of DMG cells towards CXCL12 and CCL2, as opposed to CXCL10, which showed no significant effect. These results indicate heterogeneity in chemotactic susceptibility among HGG subtypes, as all three have shown to be effective in the attraction of GB cells. For this DMG cell line, a motility trap that releases CCL2 alone or co-releases CXCL12 (for early attraction) and CCL2 (for sustained attraction) appears promising for further in vivo testing. However, additional evaluation of the temporal and dose-dependent migration of other primary DMG and GB cell lines in response to a broader panel of chemoattractants is warranted and currently in progress. [This work was funded by a project grant from the “Cancer Research Institute Ghent” (CRIG).]