MEMBRANE DISRUPTION OF THE GANGLIOSIDE-NEUROPLASTIN-PMCA NETWORK DRIVES CALCIUM DYSREGULATION IN GLIOBLASTOMA

Glioblastoma (GBM) is a highly aggressive primary brain tumor with limited treatment options and a poor prognosis. Dysregulated calcium signaling has become a key factor in gliomagenesis, but the underlying mechanisms remain unclear. This study aimed to identify the molecular components involved in calcium extrusion in GBM, focusing on a potential membrane-associated regulatory network involving gangliosides, neuroplastin (Np), and plasma membrane calcium ATPase (PMCA). A comprehensive multi-level approach was employed, including transcriptomic and epigenetic analyses of over 5,000 samples from public databases (TCGA, GTEx, cBioPortal), along with quantitative PCR, Western blotting, immunohistochemistry, ganglioside profiling via high-performance thin-layer chromatography and dot blotting, and PMCA activity assays in resected GBM samples and matched control brain tissues. Transcriptomic and proteomic data showed consistent downregulation of Np and PMCA isoforms, particularly the brain-specific Np65 and PMCA2, in GBM. This was accompanied by a pronounced decrease in PMCA activity of approximately 80% in GBM samples. Epigenetic analyses suggested that the observed downregulation of PMCA and Np expression may be partly regulated by promoter methylation and disturbed transcription factor networks. Ganglioside profiling revealed increased GD3 levels that correlated negatively with PMCA activity, whereas decreased GD1b levels correlated positively. Principal component analysis further identified GD3 as a crucial determinant of impaired PMCA function. These findings outline a new membrane connection involving gangliosides, Np, and PMCAs, in which disruption of calcium extrusion could lead to calcium overload within GBM cells. This connection offers a promising target for therapies aimed at restoring calcium balance in glioblastoma.