Low- and high-grade glioma-associated vascular cells differentially regulate tumor growth [project2]

Glioma vascular cells (GVC) from high-grade IV gliomas (HG) are molecularly and functionally distinct from normal brain EC, and secrete higher levels of pro-tumorigenic factors that promote glioma growth and progression. However, it remains unclear whether GVC from Low- Grade II/II gliomas (LG) also express pro-tumorigenic factors, and to what extent they functionally contribute to glioma growth. Here, we profile the transcriptomes of GVC from IDH-mutant (mIDH) LG and IDH-wildtype (wIDH) HG and show that they exhibit significant molecular and functional heterogeneity. LG-GVC show enrichment of extracellular matrix and cell cycle-related gene sets and sensitivity to anti-angiogenic drugs, whereas HG-GVC display an increase in immune response-related gene sets and anti-angiogenic resistance. Strikingly, conditioned media from LG-GVC inhibits the growth of wIDH glioblastoma cells, whereas HG-GVC promotes growth. In vivo co-transplantation of LG-GVC with tumor cells reduces growth, whereas HG-GVC enhances tumor growth in orthotopic xenografts. We identify ASPORIN (ASPN), a small leucine-rich repeat proteoglycan, enriched in LG-GVC as a growth suppressor of wIDH glioblastoma cells in vitro and in vivo. Together, these findings indicate that GVC from LG and HG gliomas are heterogeneous and differentially regulate tumor growth.