Identification of CRYAB+ KCNN3+ SOX9+ Astrocyte-Like and EGFR+ PDGFRA+ OLIG1+ Oligodendrocyte-Like Tumoral Cells in Diffuse IDH1-Mutant Gliomas and Implication of NOTCH1 Signalling in Their Genesis

Abstract

Diffuse grade II IDH-mutant gliomas are slow-growing brain tumors that progress into high-grade gliomas. They present intratumoral cell heterogeneity, and no reliable markers are available to distinguish the different cell subtypes. The molecular mechanisms underlying the formation of this cell diversity is also ill-defined. Here, we report that SOX9 and OLIG1 transcription factors, which specifically label astrocytes and oligodendrocytes in the normal brain, revealed the presence of two largely nonoverlapping tumoral populations in IDH1-mutant oligodendrogliomas and astrocytomas. Astrocyte-like SOX9+ cells additionally stained for APOE, CRYAB, ID4, KCNN3, while oligodendrocyte-like OLIG1+ cells stained for ASCL1, EGFR, IDH1, PDGFRA, PTPRZ1, SOX4, and SOX8. GPR17, an oligodendrocytic marker, was expressed by both cells. These two subpopulations appear to have distinct BMP, NOTCH1, and MAPK active pathways as stainings for BMP4, HEY1, HEY2, p-SMAD1/5 and p-ERK were higher in SOX9+ cells. We used primary cultures and a new cell line to explore the influence of NOTCH1 activation and BMP treatment on the IDH1-mutant glioma cell phenotype. This revealed that NOTCH1 globally reduced oligodendrocytic markers and IDH1 expression while upregulating APOE, CRYAB, HEY1/2, and an electrophysiologically-active Ca2+-activated apamin-sensitive K+ channel (KCNN3/SK3). This was accompanied by a reduction in proliferation. Similar effects of NOTCH1 activation were observed in nontumoral human oligodendrocytic cells, which additionally induced strong SOX9 expression. BMP treatment reduced OLIG1/2 expression and strongly upregulated CRYAB and NOGGIN, a negative regulator of BMP. The presence of astrocyte-like SOX9+ and oligodendrocyte-like OLIG1+ cells in grade II IDH1-mutant gliomas raises new questions about their role in the pathology.

SLUG and Truncated TAL1 Reduce Glioblastoma Stem Cell Growth Downstream of Notch1 and Define Distinct Vascular Subpopulations in Glioblastoma Multiforme

“…Recently, we have shown that Notch1 pathway activation in GSCs blocks their proliferation, inhibits ASCL1, OLIG2, and SOX2 expression, and promotes their differentiation into pericyte-like cells, both in vitro and in vivo [ 18 ]. A similar role for Notch1 activation was also observed in isocitrate dehydrogenase 1 (IDH1) mutant diffuse low-grade gliomas [ 19 ]. These studies provided us with a specific molecular signature and a non-exhaustive list of transcription factors that potentially mediate the Notch1 downstream effects.…”

Comparative single-cell RNA-sequencing profiling of BMP4-treated primary glioma cultures reveals therapeutic markers

“…IDH-mutant gliomas with high OLIG1/2 expression are highly dependent on GSCs and specifically downregulate BMP4 expression. 45,46 This dependency on GSCc might also explain the sensitivity to BMP4 we observed in OLIG1/2+ GBM cells. We also discovered that genes involved in ribosomal translation (RPL27A and RPS27) can be used as markers for early-response to BMP4.…”

miR-30c plays diagnostic and prognostic roles and mediates epithelial–mesenchymal transition (EMT) and proliferation of gliomas by affecting Notch1

“…In glioblastoma, miR-30c can impede the proliferation, migration and invasion of tumor cells by affecting Sox9 39 . The latest research showed that Notch1 activation induced strong Sox9 expression 40 . Therefore, Notch1 is more important in the pathogenesis of gliomas.…”