Vanini, J. | bioRxiv Science

bioRxiv2026

PSEN1 Expression Identifies a Developmentally Distinct Favorable-Prognosis State in SHH α Medulloblastoma

Background: Although PSEN1 is best known for its role in Alzheimer's disease, it also regulates neural development and cerebellar morphogenesis. Medulloblastoma (MB) is the most common malignant pediatric brain tumor and arises from disrupted cerebellar developmental programs. The clinical significance of PSEN1 in MB remains unknown. We investigated the prognostic value and transcriptional correlates of PSEN1 expression across molecular subgroups and subtypes of MB. Methods: Public bulk and single-cell transcriptomic datasets were used to examine PSEN1 expression, associations with overall survival (OS), and transcriptional correlates in MB. The SHH -associated transcriptional pattern was evaluated in an independent cohort, and PSEN1 expression was further examined in the developing human cerebellum and across pediatric brain tumor types. Genes strongly correlated with PSEN1 in SHH MB were subjected to Gene Ontology (GO) enrichment analysis. Results: High PSEN1 expression was consistently associated with significantly longer OS exclusively in SHH MB. The PSEN1-associated transcriptional pattern was reproduced in an independent SHH cohort. PSEN1 was expressed across developing cerebellar cell populations and pediatric brain tumor types, with MB showing intermediate expression among the tumor entities examined. In SHH MB, PSEN1 was associated with a coordinated transcriptional program enriched for RNA homeostasis, intracellular membrane trafficking, protein quality control, lipid and calcium signaling, and developmental pathways. Conclusions: High PSEN1 expression identifies a favorable-prognosis subset of SHH MB and is associated with a distinct transcriptional program related to endomembrane organization and cellular homeostasis rather than canonical SHH signaling. These findings suggest that PSEN1 may mark a developmentally distinct tumor state and generate new hypotheses regarding subtype-specific developmental programs in MB.

cancer biology↗

bioRxiv2024

Modulation of Stemness and Differentiation Regulators by Valproic Acid in Medulloblastoma

Changes in epigenetic processes such as histone acetylation are proposed as key events influencing cancer cell function and the initiation and progression of pediatric brain tumors. Valproic acid (VPA) is an antiepileptic drug that acts partially by inhibiting histone deacetylases (HDACs) and could be repurposed as an epigenetic anticancer therapy. Here, we show that VPA reduced medulloblastoma (MB) cell viability and led to cell cycle arrest. These effects were accompanied by enhanced H3K9 histone acetylation (H3K9ac) and decreased expression of the MYC oncogene. VPA impaired the expansion of MB neurospheres enriched in stemness markers and reduced MYC while increasing TP53 expression in these neurospheres. In addition, VPA induced morphological changes consistent with neuronal differentiation and the increased expression of differentiation marker genes TUBB3 and ENO2. The expression of stemness genes SOX2, NES, and PRTG was differentially affected by VPA in MB cells with different TP53 status. VPA increased H3K9 occupancy of the promoter region of TP53. Among the genes regulated by VPA, the stemness regulators MYC and NES showed an association with patient survival in specific MB subgroups. Our results indicate that VPA may exert antitumor effects in MB by influencing histone acetylation, which may result in the modulation of stemness, neuronal differentiation, and the expression of genes associated with patient prognosis in specific molecular subgroups. Importantly, the actions of VPA in MB cells and neurospheres include a reduction in the expression of MYC and an increase in TP53.

cancer biology↗