Restoration of p53 mRNA combined with BRD4 silencing by brain targeted nanocapsules achieves effective combinatorial treatment of glioblastoma

Glioblastoma (GB) is a highly malignant and the most lethal intracranial tumor. p53 mutations in GB patients, occurring in 30-50 % of cases, disrupt tumor-suppressive pathways and promote malignant progression. Advances in mRNA technology enable p53 restoration for GB therapy, but inefficient brain delivery systems limit its use. Additionally, p53 alone may not fully suppress tumors due to compensatory signaling, necessitating the targeting of multiple pathways for better effect. BRD4 is frequently overexpressed in various cancers, and its silencing triggers apoptosis through modulation of Bcl-2 family proteins, concurrently downregulating PD-L1 to inhibit immune evasion and enhance anti-tumor efficacy. Accordingly, we develop a brain-targeted nanocapsule platform based on fluorinated polyethyleneimine (PEI-PFF) for co-delivering p53 mRNA and BRD4 siRNA. ApoE peptide functionalization enables receptor-mediated transcytosis through low-density lipoprotein receptors (LDLRs) on the endothelial cells of blood-brain barrier (BBB). This platform reactivates p53-mediated tumor suppression, triggering apoptosis and immunogenic cell death while enhancing anti-tumor immune responses. Simultaneously, BRD4 silencing reduces PD-L1 expression to inhibit immune evasion and promote apoptosis. These synergistic mechanisms collectively enhance anti-tumor efficacy in vitro, induce immunogenic cell death (ICD), and trigger the secretion of cytokines (IL-10, TNF-α, IFN-γ). In GB orthotopic and recurrent mouse models, co-delivery of p53 mRNA and BRD4 siRNA significantly improved survival (54 and 71 days compared to 18 and 24 days with PBS treatment). Hence, our nanocapsules serve as a versatile platform for the concurrent restoration of tumor suppressor genes and downregulation of oncogenes, providing a promising approach for clinical application.