Targeting mesenchymal monocyte-derived macrophages to enhance the sensitivity of glioblastoma to temozolomide by inhibiting TNF/CELSR2/p65/Kla-HDAC1/EPAS1 axis.

[INTRODUCTION] Temozolomide (TMZ) resistance poses a significant challenge to the treatment of aggressive and highly lethal glioblastomas (GBM). Monocyte-derived Macrophages (MDM) within the tumor microenvironment are key factors contributing to TMZ resistance in GBM. Lactate-mediated histone lysine lactylation (Kla) plays a crucial role in the regulation of tumor progression. However, the mechanism through which MDM-induced Kla expression promotes TMZ resistance in GBM remains unclear.

[OBJECTIVES] The objective of this study s to identify a subtype of MDM with therapeutic potential target and to elucidate the mechanisms through which this subtype of MDM contributes to tumor malignant progression and TMZ resistance.

[METHODS] We integrated single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics data to evaluate whether mesenchymal (MES) MDM is associated with poor prognosis. By establishing a subtype model of GBM cells for the first time, we validated the mechanism by which MES-MDM promotes subtype conversion of tumor cells. Using patient-derived GBM organoids and an intracranial orthotopic GBM model, we demonstrated that targeting MES-MDM increased GBM sensitivity to TMZ treatment.

[RESULTS] We identified a novel MDM subtype, MES-MDM, in the hypoxic niches of the perinecrotic region characterized by high TREM1 expression, which fueled GBM progression. Hypoxia drived MES-MDM signatures by activating ATF3 transcription. MES-MDM facilitated the transition from the NPC to the MES subtype in GBM cells, in which Histone Deacetylase 1 (HDAC1) Kla, induced by the TNF-CELSR2/p65 signaling pathway, promoted this conversion, thereby promoting TMZ resistance. Targeting MES-MDM with TREM1 inhibitory peptides amplified TMZ sensitivity, offering a potential strategy for overcoming resistance to therapy in GBM. Targeting TREM1 enhanced the effectiveness of anti-PD-1 immunotherapy.

[CONCLUSION] This study provides a potential therapeutic strategy for patients with MES-subtype GBM by targeting MES-MDM in combination with TMZ or PD-1 antibody treatment.