title: NDRG4 is a novel oncogenic protein and p53 associated regulator of apoptosis in malignant meningioma cells.
abstract: Aggressive meningiomas exhibit high levels of recurrence, morbidity and mortality. When surgical and radiation options are exhausted, there is need for novel molecularly-targeted therapies. We have recently identified NDRG4 overexpression in aggressive meningiomas. NDRG4 is a member of the N-Myc Downstream Regulated Gene (NDRG) family of the alpha/beta hydrolase superfamily. We have demonstrated that NDRG4 downregulation results in decreased cell proliferation, migration and invasion. In follow up to our prior studies; here we demonstrate that the predominant form of cell death following NDRG4 silencing is apoptosis, utilizing Annexin-V flow cytometry assay. We show that apoptosis caused by p53 upregulation, phosphorylation at Ser15, BAX activation, Bcl-2 and BcL-xL downregulation, mitochondrial cytochrome c release and execution of caspases following NDRG4 depletion. Sub-cellular distribution of BAX and cytochrome c indicated mitochondrial-mediated apoptosis. In addition, we carried out the fluorescence cytochemical analysis to confirm mitochondrial-mediated apoptosis by changes in mitochondrial membrane potential (Ψm), using JC-1 dye. Immunoprecipitation and immunofluorescence confirmed binding of NDRG4 to p53. In addition, we demonstrate that apoptosis is mitochondrial and p53 dependent. The proapoptotic effect of p53 was verified by the results in which a small molecule compound PFT-α, an inhibitor of p53 phosphorylation, is greatly protected against targeting NDRG4 induced apoptosis. These findings bring novel insight to the roles of NDRG4 in meningioma progression. A better understanding of this pathway and its role in meningioma carcinogenesis and cell biology is promising for the development of novel therapeutic targets for the management of aggressive meningiomas.
authors.affiliation: Department of Radiation Oncology, Cancer Biology Division, School of Medicine, Washington University in Saint Louis, St. Louis, Missouri, USA.
authors.forename: Rama P
authors.initials: RP
authors.lastname: Kotipatruni
authors.affiliation: Department of Radiation Oncology, Cancer Biology Division, School of Medicine, Washington University in Saint Louis, St. Louis, Missouri, USA.
authors.forename: Xuan
authors.initials: X
authors.lastname: Ren
authors.affiliation: Department of Radiation Oncology, Cancer Biology Division, School of Medicine, Washington University in Saint Louis, St. Louis, Missouri, USA.|Siteman Cancer Center, Washington University in Saint Louis, St. Louis, Missouri, USA.
authors.forename: Dinesh
authors.initials: D
authors.lastname: Thotala
authors.affiliation: Department of Radiation Oncology, Cancer Biology Division, School of Medicine, Washington University in Saint Louis, St. Louis, Missouri, USA.|Siteman Cancer Center, Washington University in Saint Louis, St. Louis, Missouri, USA.
authors.forename: Jerry J
authors.initials: JJ
authors.lastname: Jaboin
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D049109:Cell Proliferation / Q000502:physiology; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D055785:Gene Knockdown Techniques; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D008577:Meningeal Neoplasms / Q000378:metabolism / Q000473:pathology*; D008579:Meningioma / Q000378:metabolism / Q000473:pathology*; D009124:Muscle Proteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D009124:Muscle Proteins; C431705:NDRG4 protein, human; D009419:Nerve Tissue Proteins; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53
keywords: NDRG4; lentiviral shRNA; meningioma; mitochondrial apoptosis; p53