GPR133 (ADGRD1), an adhesion G-protein-coupled receptor, is necessary for glioblastoma growth

Abstract

Glioblastoma (GBM) is a deadly primary brain malignancy with extensive intratumoral hypoxia. Hypoxic regions of GBM contain stem-like cells and are associated with tumor growth and angiogenesis. The molecular mechanisms that regulate tumor growth in hypoxic conditions are incompletely understood. Here, we use primary human tumor biospecimens and cultures to identify GPR133 (ADGRD1), an orphan member of the adhesion family of G-protein-coupled receptors, as a critical regulator of the response to hypoxia and tumor growth in GBM. GPR133 is selectively expressed in CD133+ GBM stem cells (GSCs) and within the hypoxic areas of PPN in human biospecimens. GPR133 mRNA is transcriptionally upregulated by hypoxia in hypoxia-inducible factor 1α (Hif1α)-dependent manner. Genetic inhibition of GPR133 with short hairpin RNA reduces the prevalence of CD133+ GSCs, tumor cell proliferation and tumorsphere formation in vitro. Forskolin rescues the GPR133 knockdown phenotype, suggesting that GPR133 signaling is mediated by cAMP. Implantation of GBM cells with short hairpin RNA-mediated knockdown of GPR133 in the mouse brain markedly reduces tumor xenograft formation and increases host survival. Analysis of the TCGA data shows that GPR133 expression levels are inversely correlated with patient survival. These findings indicate that GPR133 is an important mediator of the hypoxic response in GBM and has significant protumorigenic functions. We propose that GPR133 represents a novel molecular target in GBM and possibly other malignancies where hypoxia is fundamental to pathogenesis.

Notch signaling regulates metabolic heterogeneity in glioblastoma stem cells

“…In order to further characterize cell populations identified by activation of Notch signaling and expression of CD133, we used patient-derived tumorsphere cultures (GBML8, 20, 33, 61) [ 7 , 44 , 46 , 47 ]. Molecular subtyping of parental biospecimens was performed with DNA methylation profiling (Illumina 450K arrays) ( Supplementary Figure 2ai ) [ 47 , 48 ]. The analysis classified GBML8 in the mesenchymal, and GBML20, GBML33 and GBML61 in the RTK1 (proneural) subtypes ( Supplementary Figure 2b ).…”

“…We observed that, when animals were injected with pimonidazole i.p and Evans Blue i.v. before sacrificing, to analyze vascular perfusion and the extent of hypoxia in these tumors [ 47 , 54 ], Notch hi -initiated tumors showed elevated perfusion, while CD133 hi -initiated tumors showed less perfusion and increased hypoxia (Figure 4d, 4e ). Collectively, these findings indicate that CD133 hi cells give rise to hypo-perfusing and hypoxic tumors, in contrast to Notch hi -initiated tumors.…”

“…We followed a protocol approved by NYU Langone Medical Center’s Institutional Review Board (IRB) to procure fresh tumor tissue from consented patients undergoing surgery for resection of GBM (IRB# S12-01130). Primary human GBM cultures were obtained as previously described [ 44 , 46 , 47 ]. Four primary GBM cultures were used for the experiments described here (GBML8, GBML20 and GBML33 were used for NotchLenti experiments; GBML8, GBML20 and GBML61 were used for NICD-OE experiments) ( Supplementary Figure 1 ).…”

Adhesion G protein–coupled receptors—Candidate metabotropic mechanosensors and novel drug targets

“…However, under hypoxic conditions that occur in glioblastoma lesions the receptor becomes expressed and appears to support tumour growth explaining why ADGRD1 expression levels inversely correlate with patient survival. Reassuringly, genetic knockdown of ADGRD1 mRNA in vitro and in a mouse xenograft model reduced the number of cancerous glioblastoma stem cells, curtailed tumour formation and benefitted survival of the xenograft host . While ADGRD1 thus qualifies as a protumorigenic factor, ADGRB1 is an aGPCR that suppresses formation of another brain malignancy, medulloblastoma.…”

Impaired miRNA degradation by post-transcriptional addition of 3’ cytosine and adenine in T cell activation

“…ADGRD1 appears upregulated in a mouse model of gastrointestinal stromal tumor (Gromova et al 2009) and inversely correlates with patient survival in acute myeloid leukemia (Yang et al 2019) and glioblastoma (Bayin et al 2016). It also plays an essential role in glioblastoma growth (Bayin et al 2016;Frenster et al 2017).…”