Histone deacetylase inhibition disrupts the molecular signature of the glioblastoma secretome related to extracellular vesicle-associated proteins and targets RAB7a and RAB14 in vitro.

Glioblastoma (GBM) is the most aggressive brain tumor with a poor prognosis. While Histone Deacetylase inhibitors have shown promising results in inhibiting cancer cell invasion and promoting apoptosis, their effects on GBM secretion, specifically focusing on extracellular vesicles (EVs) secretion, remain largely unexplored. Using label-free NANOLC-MS/MS methodology, we identified significant changes in the abundance of membrane traffic regulatory proteins in the secretome of U87MG cells after the treatment with the HDAC inhibitor Trichostatin A (TSA). In silico analysis showed that TSA treatment disrupted the secretion pattern of EVs-associated proteins and cellular signaling pathways, both qualitatively and quantitatively. Notably, RAB14/RAB7a interaction was only observed in the secretome of cells treated with TSA. In vitro assays revealed that TSA treatment of glioma cells increased EVs secretion and intracellular protein levels of RAB7a and RAB14 without affecting gene expression, suggesting a role of these two EVs-associated proteins in grade IV glioma cells. Additionally, an integrative approach using clinical data highlighted a correlation between DNA mutations affecting vesicle traffic coding-genes and clinical and phenotypic outcomes in glioma patients. These findings provide insights into the interplay between epigenetics and GBM intracellular trafficking, potentially leading to improved strategies for targeting and modifying the complex signaling network established between GBM cells and the tumor cell microenvironment.