Overexpression of HGF/MET axis along with p53 inhibition induces de novo glioma formation in mice

BACKGROUND: Aberrant MET receptor tyrosine kinase (RTK) activation leads to invasive tumor growth in different types of cancer. Overexpression of MET and its ligand hepatocyte growth factor (HGF) occurs more frequently in glioblastoma (GBM) than in low-grade gliomas. Although we have shown previously that HGF-autocrine activation predicts sensitivity to MET tyrosine kinase inhibitors (TKIs) in GBM, whether it initiates tumorigenesis remains elusive. METHODS: Using a well-established Sleeping Beauty (SB) transposon strategy, we injected human HGF and MET cDNA together with a short hairpin siRNA against Trp53 (SB-hHgf.Met.ShP53) into the lateral ventricle of neonatal mice to induce spontaneous glioma initiation and characterized the tumors with H&E and immunohistochemistry analysis. Glioma sphere cells also were isolated for measuring the sensitivity to specific MET TKIs. RESULTS: Mixed injection of SB-hHgf.Met.ShP53 plasmids induced de novo glioma formation with invasive tumor growth accompanied by HGF and MET overexpression. While glioma stem cells (GSCs) are considered as the tumor-initiating cells in GBM, both SB-hHgf.Met.ShP53 tumor sections and glioma spheres harvested from these tumors expressed GSC markers nestin, GFAP, and Sox 2. Moreover, specific MET TKIs significantly inhibited tumor spheres’ proliferation and MET/MAPK/AKT signaling. CONCLUSIONS: Overexpression of the HGF/MET axis along with p53 attenuation may transform neural stem cells into GSCs, resulting in GBM formation in mice. These tumors are primarily driven by the MET RTK pathway activation and are sensitive to MET TKIs. The SB-hHgf.Met.ShP53 spontaneous mouse glioma model provides a useful tool for studying GBM tumor biology and MET-targeting therapeutics.