Pterostilbene as a pyroptosis inducer and tumor microenvironment regulator inhibits glioblastoma and enhances the efficacy of immunotherapy

Glioblastoma (GBM) is a highly invasive tumor type associated with a high mortality rate, and the efficacy of traditional chemotherapy, targeted therapy, and immunotherapy for GBM remains limited. Therefore, there is an urgent need to develop novel therapeutic agents and strategies to combat GBM effectively. The upregulation of the pivotal pyroptosis protein GSDME in GBM suggests that harnessing cellular pyroptosis may be a promising approach for anti-GBM treatment. This study revealed that the natural polyphenol pterostilbene (PTE) induces pyroptosis and inhibits proliferation in GBM cells. Network pharmacology, western blot analysis, LDH release experiments, and damage-associated molecular pattern (DAMP) detection collectively confirmed that PTE triggers CASP3/GSDME-dependent pyroptosis but not GSDMD-dependent pyroptosis in GBM cells. Molecular docking, RNA-seq, microscale thermophoresis (MST), and western blot analyses revealed that PTE inhibited STAT3 activation while activating a potential regulatory loop dependent on mitochondrial reactive oxygen species (ROS) accumulation to initiate the CASP3/GSDME pathway and promote cell pyroptosis. PTE treatment exerts direct antitumor effects by inducing both apoptosis and pyroptosis in glioblastoma (GBM) cells. Furthermore, it upregulates the expression of pro-inflammatory factors within tumor tissues, enhances the infiltration of CD8+ T cells in both the tumor microenvironment and spleen, increases the proportion of M1-type tumor-associated macrophages (TAMs), and decreases the proportion of regulatory T cells (Tregs) in the tumor microenvironment, thereby effectively reversing the immunosuppressive milieu. Further investigations showed that combining PTE with immune checkpoint inhibitors aPD-1 enhanced the infiltration of potent antitumor immune cells, significantly inhibiting mouse tumor growth and prolonging survival. Our study provides a new mechanistic basis for the therapeutic development of PTE as a pyroptosis inducer in the GBM tumor microenvironment that can enhance the efficacy of aPD-1 immunotherapy, opening new possible avenues for the treatment of this high-mortality tumor type.