A PTX3/TLR4 axis sustains SHH-Medulloblastoma growth and defines a new therapeutic vulnerability

Sonic hedgehog-medulloblastoma (SHH-MB) represents a biologically diverse and clinically challenging subgroup, especially in high-risk variants characterized by metastatic dissemination. Despite progress in molecular stratification, current treatments rely on intensive multimodal regimens associated with substantial long-term neurotoxicity. Identifying novel oncogenic mechanisms that can be therapeutically exploited is therefore a critical priority.

We combined transcriptomic analyses of patient datasets with immunohistochemistry, RNAscope, and protein profiling to evaluate PTX3 expression in MB subgroups. Functional studies were performed in SHH-MB cell lines following PTX3 knockdown or knockout. Effects on proliferation, migration, and angiogenesis were assessed through multiple in vitro assays. In vivo relevance was tested using subcutaneous and orthotopic xenograft models. Mechanistic insights were obtained through phospho-kinase arrays, Western blotting and GSEA. A high-throughput drug screen and combination studies with specific inhibitors and standard chemotherapy (vincristine/cisplatin/cyclophosphamide; VCC) were performed to assess therapeutic potential.

Our results reveal that PTX3 was strongly enriched in SHH-MB subgroup, where it supported proliferation, motility, and angiogenesis. Mechanistically, PTX3 activated a TLR4-dependent IRAK1/PI3K-Akt/GSK-3/β-catenin signaling cascade. Genetic downregulation or pharmacologic blockade of PTX3-TLR4 significantly reduced tumor growth and angiogenesis in vivo. Moreover, the TLR4 inhibitor TAK-242 markedly impacted SHH-MB growth in vitro, and combination therapy of TAK-242 and VCC produced additive/synergistic effects in vitro and significantly prolonged survival in orthotopic SHH-MB-bearing mice.

Our findings identify PTX3-TLR4 signaling as key oncogenic driver and a promising therapeutic vulnerability in SHH-MB. Targeting this pathway enhances the efficacy of standard therapy and represents a rationale for mechanism-based combination strategies.