Delta and Notch-like epidermal growth factor-related receptor suppresses human glioma growth by inhibiting oncogene TOR4A.

Delta and Notch-like endothelial growth factor-related receptor (DNER) is a transmembrane protein that mediates signal communication between neurons and glial cells. This study was performed to elucidate the specific mechanism by which DNER inhibits human glioma growth. RNA sequencing was used to detect differentially expressed genes after DNER inhibition in glioma cells. The functions of the Torsin family 4 member A (TOR4A) gene were explored through cell proliferation and clonogenic assays, flow cytometric analysis, in vitro cell migration and invasion assays, in vivo glioma transplantation, and human glioma tissue analysis using the Chinese Glioma Genome Atlas database. Protein expression levels were determined using the western blot assay. We found that TOR4A was highly expressed after the inhibition of DNER in glioma cells. The prognosis of patients with gliomas that expressed high levels of TOR4A was worse than those with low levels of the protein. TOR4A promoted the proliferation of glioma cells and inhibited their apoptosis, likely by enhancing the expression of phosphorylated protein kinase B (p-AKT) and inhibiting that of antiapoptotic proteins. We confirmed that TOR4A is an oncogene and that DNER acts as a tumor suppressor gene by inhibiting TOR4A and its functions of promoting p-AKT and inhibiting antiapoptotic protein expression.