An oncogenic splice variant of PDGFRα in adult glioblastoma as a therapeutic target for selective CDK4/6 inhibitors.

Understanding human genome alterations is necessary to optimize genome-based cancer therapeutics. However, some newly discovered mutations remain as variants of unknown significance (VUS). Here, the mutation c.1403A > G in exon 10 of the platelet-derived growth factor receptor-alpha (PDGFRA) gene, a VUS found in adult glioblastoma multiforme (GBM), was introduced in human embryonal kidney 293 T (HEK293T) cells using genome editing to investigate its potential oncogenic functions. Genome editing was performed using CRISPR/Cas9; the proliferation, drug sensitivity, and carcinogenic potential of genome-edited cells were investigated. We also investigated the mechanism underlying the observed phenotypes. Three GBM patients carrying the c.1403A > G mutation were studied to validate the in vitro results. The c.1403A > G mutation led to a splice variant (p.K455_N468delinsN) because of the generation of a 3'-acceptor splice site in exon 10. PDGFRA-mutated HEK293T cells exhibited a higher proliferative activity via PDGFRα and the cyclin-dependent kinase (CDK)4/CDK6-cyclin D1 signaling pathway in a ligand-independent manner. They showed higher sensitivity to multi-kinase, receptor tyrosine kinase, and CDK4/CDK6 inhibitors. Of the three GBM patients studied, two harbored the p.K455_N468delinsN splice variant. The splicing mutation c.1403A > G in PDGFRA is oncogenic in nature. Kinase inhibitors targeting PDGFRα and CDK4/CDK6 signaling should be evaluated for treating GBM patients harboring this mutation.