PDGFRA gene rearrangements are frequent genetic events in PDGFRA-amplified glioblastomas

Abstract

Gene rearrangement in the form of an intragenic deletion is the primary mechanism of oncogenic mutation of the epidermal growth factor receptor (EGFR) gene in gliomas. However, the incidence of platelet-derived growth factor receptor-a (PDGFRA) gene rearrangement in these tumors is unknown. We investigated the PDGFRA locus in PDGFRA-amplified gliomas and identified two rearrangements, including the first case of a gene fusion between kinase insert domain receptor (KDR) (VEGFRII) and the PDGFRA gene, and six cases of PDGFRA D8, 9 , an intragenic deletion rearrangement. The PDGFRA D8, 9 mutant was common, being present in 40% of the glioblastoma multiformes (GBMs) with PDGFRA amplification. Tumors with these two types of PDGFRA rearrangement displayed histologic features of oligodendroglioma, and the gene products of both rearrangements showed constitutively elevated tyrosine kinase activity and transforming potential that was reversed by PDGFR blockade. These results suggest the possibility that these PDGFRA mutants behave as oncogenes in this subset of gliomas, and that the prevalence of such rearrangements may have been considerably underestimated.[Keywords: Copy number alteration; glioma; PDGFRA gene rearrangement; receptor tyrosine kinase] Supplemental material is available at http://www.genesdev.org.

A practical review of prognostic correlations of molecular biomarkers in glioblastoma

“…PDGFR is mutated in up to 30% of GBMs, 5 and the PDGFRAD8,9 isoform (with a deletion of exons 8 and 9) results in constitutive activation and is seen in 40% of GBMs. 35 In a recent study, PDGFRA amplification was seen in 23% of GBM cases and demonstrated a significant reduction in median survival in only the IDH1 mutation subgroup (16.0 vs 72.6 months). 38 Despite the importance of PDGF in GBM proliferation-as it is found upstream of important signaling pathways such as AKT, involved with in vitro growth of GBM, and used in animal models of GBM-no definitive role in predicting prognosis has been seen in clinical studies.…”

Critical Molecular and Genetic Markers in Primary Brain Tumors with Their Clinical Importance

“…One of them, the most significant one regarding GBM, is PDGFRA. The other isoform is also PDGFRAD (with a deletion of exons 8 and 9), seen in 40% of GBMs, and leads to constitutive activation [14,15]. According to the Cancer Genome Atlas, PDGFRA has a crucial role in the proneural subtype of GBM; however, no changes were observed in prognosis of the evaluated patients [16].…”

Validation of a High-Content Screening Assay Using Whole-Well Imaging of Transformed Phenotypes

“…Therefore, to better observe the cytoplasm of cells, we used fluorescent GFP protein that was encoded by the plasmid used to express the oncogene KP into NIH-3T3 cells (KP cells). 13 The resulting images taken at three different focal planes (3,8, and 14 mm), using the INCA3000, clearly show that the KPtransformed cells form transformed clusters with cells pilling up on top of each other (Fig. 1C, D).…”

“…13 KP cells and the parental NIH-3T3 cells were cultured under a humidified atmosphere at 378C/5% CO 2 -95% air in complete Dulbecco's modified Eagle's medium (ATCC: ) containing 10% heat-inactivated calf serum (Colorado Serum Co.: CS1334), 100 units/mL penicillin, and 100 mg/mL streptomycin.…”

“…13 When introduced into NIH-3T3 cells, the resulting KP cells have a morphologically transformed phenotype characterized by the formation of clusters as imaged by brightfield microscopy (Fig. 1A).…”