SHP-2/PTPN11 mediates gliomagenesis driven by PDGFRA and INK4A/ARF aberrations in mice and humans

Recent collaborative efforts have subclassified malignant glioblastomas into 4 clinical relevant subtypes based on their signature genetic lesions. Platelet-derived growth factor receptor alpha (PDGFRA) overexpression is concomitant with a loss of cyclin-dependent kinase inhibitor 2A (CDKN2A) locus (encoding P16INK4A and P14ARF) in a large number of tumors within one subtype of glioblastomas. Here we report that activation of PDGFR alpha conferred tumorigenicity to Thk4a/Arf-deficient mouse astrocytes and human glioma cells in the brain. Restoration of p16INK4a but not p19ARF suppressed PDGFR alpha-promoted glioma formation. Mechanistically, abrogation of signaling modules in PDGFR alpha that lost capacity to bind to SHP-2 or PI3K significantly diminished PDGFR alpha-promoted tumorigenesis. Furthermore, inhibition of SHP-2 by shRNAs or pharmacological inhibitors disrupted the interaction of PI3K with PDGFR alpha, suppressed downstream AKT/mTOR activation, and impaired tumorigenesis of Ink4a/Arf-null cells, whereas expression of an activated PI3K mutant rescued the effect of SHP-2 inhibition on tumorigenicity. PDGFR alpha and PDGF-A are co-expressed in clinical glioblastoma specimens, and such co-expression is linked with activation of SHP-2/AKT/mTOR signaling. Together, our data suggest that in glioblastomas with Ink4a/Arf deficiency, overexpressed PDGFR alpha promotes tumorigenesis through the PI3K/AKT/mTOR-mediated pathway regulated by SHP-2 activity. These findings functionally validate the genomic analysis of glioblastomas and identify SHP-2 as a potential target for treatment of glioblastomas.