CSIG-10. PLATELET-DERIVED GROWTH FACTOR RECEPTOR ALPHA ONCOGENE DEPENDENCY IN GLIOBLASTOMA

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi35-vi35
Author(s):  
Artem Berezovsky ◽  
Indrani Datta ◽  
Ruicong She ◽  
Andrea Transou ◽  
Susan Irtenkauf ◽  
...  
Keyword(s):  
Growth Factor ◽  
Tumor Growth ◽  
Single Cell ◽  
Copy Number ◽  
De Novo ◽  
Platelet Derived Growth Factor ◽  
Rank Test ◽  
Tumor Growth Rate ◽  
Cell Clones

Abstract PDGFRA is the second most frequently amplified gene encoding receptor tyrosine kinase in adult glioblastoma (GBM), oftentimes as extrachromosomal elements (ecDNA). Our overall objective is to elucidate mechanisms underlying PDGFRα dependency in GBM tumor maintenance. We have isolated distinct subpopulations from a GBM model (HF3253), harboring two alterations in PDGFRA: constitutively active genomic rearrangement and extrachromosomal amplification, that differ in the frequency of PDGFRA ecDNA. HF3253 tumor growth rate correlates with the initial proportion of ecDNA+ population implanted. Furthermore, slower tumor growth is due to selection for initially low-frequency PDGFRA ecDNA amplified clones based on histology and TaqMan Copy Number assay. Further exploiting intra-tumoral heterogeneity, we have isolated single cell clones from bulk cells. Compared to bulk cells, single cell clones do not express PDGFRα, PDGFRA mRNA and exhibit diploid PDGFRA copy number. Tumor growth was reduced in 4 ecDNA(-) clones compared to parental ecDNA(+) (log-rank test p= 0.00772, 0.00379, 0.00076, 0.00379). In contrast to parental HF3253, ecDNA(-) tumors demonstrated diffuse tumor morphology and weak PDGFRα activation. HF3253 ecDNA(-) PDX tumors lack detectable PDGFRα. Correspondingly, HF3253 ecDNA(-) cell populations do not exhibit de novo PDGFRA copy number gains post-implant. We conducted paired, whole RNA-sequencing on 20 HF3253 populations (ecDNA+/-: 6 clones from 3 biological replicates PDXs and 4 clones from 4 in vitro technical replicates). Employing a false discovery rate of 0.05, we identified 785 differentially expressed genes. Platelet-derived growth factor binding (GO:0048407) and central carbon metabolism were down-regulated in ecDNA(-) while genes significantly associated with astrocytic processes were upregulated. We demonstrated the dependency on PDGFRα signaling in a patient-derived GBM model carrying ecDNA PDGFRA amplification. Our data validates PDGFRɑ as a therapeutic target in a subset of GBM patients and demonstrates that detection of ecDNA-amplified PDGFRA has the potential to be a predictive biomarker of future PDGFRɑ targeted therapies.

scholarly journals CSIG-06. PLATELET DERIVED GROWTH FACTOR RECEPTOR ALPHA AS AN ONCOGENIC DRIVER IN GLIOBLASTOMA

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii28-ii29
Author(s):  
Artem Berezovsky ◽  
Susan Irtenkauf ◽  
Andrea Transou ◽  
Laura Hasselbach ◽  
Tom Mikkelsen ◽  
...  
Keyword(s):  
Growth Factor ◽  
Tumor Growth ◽  
Growth Factor Receptor ◽  
Low Frequency ◽  
Normal Growth ◽  
Predictive Biomarker ◽  
Platelet Derived Growth Factor ◽  
Rank Test ◽  
Receptor Alpha ◽  
Factor Receptor Alpha

Abstract Activated platelet derived growth factor receptor alpha (PDGFRα) is essential for the maintenance of oligodendrocyte progenitors. Differential signaling results from phosphorylation of specific tyrosine residues in the kinase insert (KI) domain present in most RTKs in variable length. Our goal is to identify the molecular contexts in which PDGFRA activation is an essential driver for maintenance of the malignant phenotype in glioblastoma. RNA sequencing was conducted on 13 glioblastoma mouse orthotopic PDXs (n=3/line). PDGFRA mRNA overexpression was observed for 3 glioblastomas: one carrying PDGFRA extrachromosomal (ecDNA) amplification (HF3253) and two non-amplified (Tukey p=0.41, 0.19). Corresponding PDGFRα KI activation (pY754) was observed only for HF3253. To assess activation as an adaptation to microenvironmental pressures, pY754 was quantified by reverse phase protein array on 4 growth conditions (normal, -growth factors, two serum concentrations) for 8 neurospheres. PDGFRɑ activation was highest in growth factor-depleted conditions in the absence of exogenous ligand (Tukey p=0.02). Taking advantage of genomic heterogeneity in HF3253, we isolated cellular lineages with divergent frequencies of PDGFRA ecDNA. PDGFRA copy number (TaqMan) decreased longitudinally. PDX tumors from higher passage had slower tumor growth due to strong selection for initial low frequency PDGFRA ecDNA-amplified clones. IHC showed that the tumors had comparably high total and activated PDGFRα to low passage tumors. Further exploiting intra-tumoral heterogeneity, we have isolated single cell clones. Tumor growth was reduced in 2 ecDNA(-) tumors compared to parental ecDNA(+) (log-rank test p= 3e-3, 1e-3). In contrast to parental, ecDNA(-) tumors demonstrated diffuse tumor morphology and weak PDGFRα activation. The staining index (mean intensity x area) for the ecDNA(-) clones was significantly lower than the ecDNA(+) (1-wayANOVA p=2e-16). We established dependency on PDGFRα signaling in a patient-derived glioblastoma model. Our data demonstrates that detection of ecDNA-amplified PDGFRA has the potential to be a predictive biomarker of future PDGFRɑ-targeted therapies.

Basis of hematopoietic defects in platelet-derived growth factor (PDGF)-B and PDGF β-receptor null mice

Blood ◽  
2001 ◽  
Vol 97 (7) ◽  
pp. 1990-1998 ◽  
Author(s):  
Wolfgang E. Kaminski ◽  
Per Lindahl ◽  
Nancy L. Lin ◽  
Virginia C. Broudy ◽  
Jeffrey R. Crosby ◽  
...  
Keyword(s):  
Growth Factor ◽  
Fetal Liver ◽  
Liver Cells ◽  
Platelet Derived Growth Factor ◽  
Wild Type ◽  
Liver Growth ◽  
Hematologic Disorders ◽  
Fetal Liver Cells ◽  
Β Receptor

Abstract Platelet-derived growth factor (PDGF)-B and PDGF β-receptor (PDGFRβ) deficiency in mice is embryonic lethal and results in cardiovascular, renal, placental, and hematologic disorders. The hematologic disorders are described, and a correlation with hepatic hypocellularity is demonstrated. To explore possible causes, the colony-forming activity of fetal liver cells in vitro was assessed, and hematopoietic chimeras were demonstrated by the transplantation of mutant fetal liver cells into lethally irradiated recipients. It was found that mutant colony formation is equivalent to that of wild-type controls. Hematopoietic chimeras reconstituted with PDGF-B−/−, PDGFRβ−/−, or wild-type fetal liver cells show complete engraftment (greater than 98%) with donor granulocytes, monocytes, B cells, and T cells and display none of the cardiovascular or hematologic abnormalities seen in mutants. In mouse embryos, PDGF-B is expressed by vascular endothelial cells and megakaryocytes. After birth, expression is seen in macrophages and neurons. This study demonstrates that hematopoietic PDGF-B or PDGFRβ expression is not required for hematopoiesis or integrity of the cardiovascular system. It is argued that metabolic stress arising from mutant defects in the placenta, heart, or blood vessels may lead to impaired liver growth and decreased production of blood cells. The chimera models in this study will serve as valuable tools to test the role of PDGF in inflammatory and immune responses.

Platelet-derived growth factor (PDGF)-dependent association of phospholipase C-gamma with the PDGF receptor signaling complex

1990 ◽  
Vol 10 (5) ◽  
pp. 2359-2366
Author(s):  
D K Morrison ◽  
D R Kaplan ◽  
S G Rhee ◽  
L T Williams
Keyword(s):  
Growth Factor ◽  
Tyrosine Phosphorylation ◽  
Serine Phosphorylation ◽  
Platelet Derived Growth Factor ◽  
Pdgf Receptor ◽  
Wild Type ◽  
Receptor Proteins ◽  
Signaling Complex

We investigated the interaction of phospholipase C-gamma (PLC-gamma) with wild-type and mutant forms of the platelet-derived growth factor (PDGF) beta-receptor both in vivo and in vitro. After PDGF treatment of CHO cell lines expressing wild-type or either of two mutant (delta Ki and Y825F) PDGF receptors, PLC-gamma became tyrosine phosphorylated and associated with the receptor proteins. The receptor association and tyrosine phosphorylation of PLC-gamma correlated with the ability of these receptors to mediate ligand-induced phosphatidylinositol turnover. However, both the delta Ki and Y825F mutant receptors were deficient in transmitting mitogenic signals, suggesting that the PDGF-induced tyrosine phosphorylation and receptor association of PLC-gamma are not sufficient to account for the growth-stimulatory activity of PDGF. Wild-type and delta Ki mutant PDGF receptor proteins expressed with recombinant baculovirus vectors also associated in vitro with mammalian PLC-gamma. However, baculovirus-expressed c-fms, v-fms, c-src, and Raf-1 proteins failed to associate with PLC-gamma under similar conditions. Phosphatase treatment of the baculovirus-expressed PDGF receptor greatly decreased its association with PLC-gamma. This requirement for receptor phosphorylation was also observed in vivo, where PLC-gamma could not associate with a mutant PDGF receptor (K602A) defective in autophosphorylation. PLC-gamma also coimmunoprecipitated with two other putative receptor substrates, the serine-threonine kinase Raf-1 and the 85-kilodalton phosphatidylinositol-3' kinase, presumably through its association with the ligand-activated receptor. Furthermore, baculovirus-expressed Raf-1 phosphorylated purified PLC-gamma in vitro at sites which showed increased serine phosphorylation in vivo in response to PDGF. These results suggest that PDGF directly influences PLC activity by inducing the association of PLC-gamma with a receptor signaling complex, resulting in increased tyrosine and serine phosphorylation of PLC-gamma.

Regulation of the transcript for a lysosomal protein: evidence for a gene program modified by platelet-derived growth factor

1985 ◽  
Vol 5 (10) ◽  
pp. 2582-2589
Author(s):  
K K Frick ◽  
P J Doherty ◽  
M M Gottesman ◽  
C D Scher
Keyword(s):  
Growth Factor ◽  
De Novo ◽  
Platelet Derived Growth Factor ◽  
Tumor Promoter ◽  
3T3 Cells ◽  
Somatomedin C ◽  
Epidermal Growth ◽  
Rna Accumulation ◽  
De Novo Protein Synthesis ◽  
Lysosomal Protein

Platelet-derived growth factor (PDGF) stimulates density-arrested BALB/c-3T3 cells to synthesize MEP, a lysosomal protein. This enhanced synthesis appears to be largely regulated by the PDGF-modulated accumulation of MEP mRNA, a 1.8-kilobase species. The increase in the MEP transcript, which is dependent on the PDGF concentration, begins 3 to 4 h after PDGF addition and is maximal at 12 h. The accumulation of the MEP transcript is growth-factor specific: PDGF and the tumor promoter 12-O-tetradecanoylphorbol-13-acetate, an agent which acts like PDGF, induce MEP RNA accumulation, whereas epidermal growth factor, somatomedin C, insulin, and whole plasma do not. A spontaneously transformed BALB/c-3T3 cell line (ST2-3T3), which does not require PDGF for growth, optimally expresses MEP RNA in the absence of PDGF. The PDGF-modulated increase in MEP RNA is unlike PDGF-modulated c-myc and c-fos RNA accumulation because it is blocked by cycloheximide, suggesting a requirement for de novo protein synthesis. It appears that PDGF modulates a program of gene expression with the accumulation of some transcripts, typified by MEP, being dependent upon the translation of others.

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