Formyl peptide receptor 2 activation by MR-39 inhibits glioblastoma cell proliferation and invasiveness through suppression of multiple oncogenic pathways

Glioblastoma (GBM) is the most common, aggressive and poor prognosis malignant brain tumor in adults, that is still orphan of effective medical treatments. The formyl peptide receptor 2 (FPR2), a G protein– coupled receptor implicated in inflammation and cancer biology, has emerged as a potential therapeutic target, yet its role in GBM remains poorly defined. We investigated the effects of MR-39, a novel selective FPR2 agonist, in three human GBM cell lines (U87MG, U138-MG, U251-MG). Antiproliferative effects were assessed via CCK-8 assays, cell counts, Ki67 immunostaining, and cell cycle analysis. The specificity of MR-39 was tested using the FPR2 antagonist WRW4 and siRNA-mediated knockdown. Whole-transcriptome analysis, RT-qPCR, Western Blot, woundhealing assays, in vitro tube formation assay, and hypoxia models were used to explore its impact on invasion, angiogenesis, and hypoxia-driven pathways. MR-39 significantly reduced proliferation in all GBM cell lines and induced a non-canonical, p53dependent S-phase arrest associated with the inhibition of both MAPK/ERK and AKT pathways. These effects were reversed by the FPR2 antagonist WRW4 or by FPR2 silencing. Transcriptomic and functional assays revealed downregulation of epithelial-to-mesenchymal transition (EMT) drivers, including Neuralcadherin (N-cadherin), Snail Family Transcriptional Repressor 2 (Slug), Snail Family Transcriptional Repressor 1 (Snail), matrix metalloproteinase-2 (MMP2), fibronectin 1 (FN1), and increased Epithelialcadherin (E-cadherin) expression, resulting in impaired migration. MR-39 displays anti-angiogenic and anti-hypoxia related activities, indeed it is able to inhibit Vascular Endothelial Growth Factor (VEGF) and Vascular Endothelial-cadherin (VE-cadherin) expression, to disrupt endothelial network formation, and to attenuate Hypoxia Inducible Factor 1 Subunit Alpha (HIF-1α) stabilization under hypoxic conditions. Notably, MR-39 exhibited significant anti-inflammatory effects, as evidenced by the downregulation of pro-inflammatory genes, including Cyclooxygenase 2 (COX-2), Chemokine (C-X-C Motif) Ligand 7. (CXCL-7), Nuclear Factor Kappa B Subunit 1 (NFKB1), Interleukin 1 Beta (IL-1β), and Interleukin 6 (IL6), and the inhibition of NF-κB protein levels. This study identifies MR-39 as a potent modulator of FPR2, and identifies its mechanisms of action in GBM, such as anti-tumor activity, including S-phase arrest, inhibition of EMT, and suppression of both angiogenesis and hypoxic adaptation. By directing FPR2 signaling toward an anti-tumor profile, MR-39 represents a promising therapeutic candidate for GBM.