SMPD3suppresses IDH mutant tumor growth via dual autocrine-paracrine roles

Abstract

Oligodendrogliomas are lower-grade, slow-growing gliomas that are ultimately fatal. Although driver mutations are known, the mechanisms underlying their signature slow growth rates are poorly understood. We found evidence for intra-tumoral interactions between neoplastic and nonneoplastic cells in oligodendroglioma tissues. To further study these cell interactions, we used two patient-derived oligodendroglioma cell lines of lower and higher aggressivity. Both oligodendroglioma cell lines released extracellular vesicles that had cytotoxic effects on nonneoplastic and neoplastic cells, but each had distinct vesicular proteomes. Consistent with extracellular vesicles mediating growth inhibitory effects in oligodendrogliomas, higher expression levels of several extracellular vesicle biogenesis genes (SMPD3,TSG101, STAM1) correlates with longer survival in oligodendroglioma patients. Furthermore, SMPD3 overexpression slows oligodendroglioma cell growth in culture. Conversely, SMPD3 knockdown enhances oligodendroglioma proliferation in vitro, in murine xenografts, and in human cerebral organoid co-cultures. Oligodendroglioma-derived extracellular vesicles thus mediate tumor cell microenvironmental interactions that contribute to low aggressivity.