title: Knockdown of NAT12/NAA30 reduces tumorigenic features of glioblastoma-initiating cells.
abstract: BACKGROUND
  Glioblastoma (GBM) is the most common primary brain malignancy and confers a dismal prognosis. GBMs harbor glioblastoma-initiating cells (GICs) that drive tumorigenesis and contribute to therapeutic resistance and tumor recurrence. Consequently, there is a strong rationale to target this cell population in order to develop new molecular therapies against GBM. Accumulating evidence indicates that Nα-terminal acetyltransferases (NATs), that are dysregulated in numerous human cancers, can serve as therapeutic targets.
  
  
  METHODS
  Microarrays were used to study the expression of several NATs including NAT12/NAA30 in clinical samples and stem cell cultures. The expression of NAT12/NAA30 was analyzed using qPCR, immunolabeling and western blot. We conducted shRNA-mediated knockdown of NAT12/NAA30 gene in GICs and studied the effects on cell viability, sphere-formation and hypoxia sensitivity. Intracranial transplantation to SCID mice enabled us to investigate the effects of NAT12/NAA30 depletion in vivo. Using microarrays we identified genes and biochemical pathways whose expression was altered upon NAT12/NAA30 down-regulation.
  
  
  RESULTS
  While decreased expression of the distal 3'UTR of NAT12/NAA30 was generally observed in GICs and GBMs, this gene was strongly up-regulated at the protein level in GBM and GICs. The increased protein levels were not caused by increased levels of the steady state mRNA but rather by other mechanisms. Also, shorter 3'UTR of NAT12/NAA30 correlated with poor survival in glioma patients. As well, we observed previously not described nuclear localization of this typically cytoplasmic protein. When compared to non-silencing controls, cells featuring NAT12/NAA30 knockdown exhibited reduced cell viability, sphere-forming ability, and mitochondrial hypoxia tolerance. Intracranial transplantation showed that knockdown of NAT12/NAA30 resulted in prolonged animal survival. Microarray analysis of the knockdown cultures showed reduced levels of HIF1α and altered expression of several other genes involved in the hypoxia response. Furthermore, NAT12/NAA30 knockdown correlated with expressional dysregulation of genes involved in the p53 pathway, ribosomal assembly and cell proliferation. Western blot analysis revealed reduction of HIF1α, phospho-MTOR(Ser2448) and higher levels of p53 and GFAP in these cultures.
  
  
  CONCLUSIONS
  NAT12/NAA30 plays an important role in growth and survival of GICs possibly by regulating hypoxia response (HIF1α), levels of p-MTOR (Ser2448) and the p53 pathway.
authors: Vilhelm Magnus Laboratory for Neurosurgical Research, Institute for Surgical Research and Department of Neurosurgery, Oslo University Hospital, Oslo, Norway. awaisam@gmail.com.|SFI-CAST-Cancer Stem Cell Innovation Center, Oslo University Hospital, Oslo, Norway. awaisam@gmail.com.
authors: Awais A
authors: AA
authors: Mughal
authors: Vilhelm Magnus Laboratory for Neurosurgical Research, Institute for Surgical Research and Department of Neurosurgery, Oslo University Hospital, Oslo, Norway. zanina_grieg@yahoo.no.|Norwegian Center for Stem Cell Research, Department of Immunology and Transfusion Medicine, Oslo University Hospital, Oslo, Norway. zanina_grieg@yahoo.no.
authors: Zanina
authors: Z
authors: Grieg
authors: Vilhelm Magnus Laboratory for Neurosurgical Research, Institute for Surgical Research and Department of Neurosurgery, Oslo University Hospital, Oslo, Norway. havard@skjellegrind.no.
authors: Håvard
authors: H
authors: Skjellegrind
authors: Vilhelm Magnus Laboratory for Neurosurgical Research, Institute for Surgical Research and Department of Neurosurgery, Oslo University Hospital, Oslo, Norway. artem.fayzullin@rr-research.no.
authors: Artem
authors: A
authors: Fayzullin
authors: Vilhelm Magnus Laboratory for Neurosurgical Research, Institute for Surgical Research and Department of Neurosurgery, Oslo University Hospital, Oslo, Norway. lamkhannat@gmail.com.
authors: Mustapha
authors: M
authors: Lamkhannat
authors: Vilhelm Magnus Laboratory for Neurosurgical Research, Institute for Surgical Research and Department of Neurosurgery, Oslo University Hospital, Oslo, Norway. mrinaj@medisin.uio.no.|Norwegian Center for Stem Cell Research, Department of Immunology and Transfusion Medicine, Oslo University Hospital, Oslo, Norway. mrinaj@medisin.uio.no.|Laboratory of Neural Development and Optical Recording (NDEVOR), Department of Physiology, Institute of Basic Medical Sciences University of Oslo, Oslo, Norway. mrinaj@medisin.uio.no.
authors: Mrinal
authors: M
authors: Joel
authors: Institute for Surgical Research, Oslo University Hospital and Center for Heart Failure Research, University of Oslo, Oslo, Norway. Muhammad.Shakil.Ahmed@rr-research.no.
authors: M Shakil
authors: MS
authors: Ahmed
authors: Vilhelm Magnus Laboratory for Neurosurgical Research, Institute for Surgical Research and Department of Neurosurgery, Oslo University Hospital, Oslo, Norway. wayne.murrell@rr-research.no.
authors: Wayne
authors: W
authors: Murrell
authors: Vilhelm Magnus Laboratory for Neurosurgical Research, Institute for Surgical Research and Department of Neurosurgery, Oslo University Hospital, Oslo, Norway. einar.vik-mo@rr-research.no.|SFI-CAST-Cancer Stem Cell Innovation Center, Oslo University Hospital, Oslo, Norway. einar.vik-mo@rr-research.no.|Norwegian Center for Stem Cell Research, Department of Immunology and Transfusion Medicine, Oslo University Hospital, Oslo, Norway. einar.vik-mo@rr-research.no.
authors: Einar O
authors: EO
authors: Vik-Mo
authors: Vilhelm Magnus Laboratory for Neurosurgical Research, Institute for Surgical Research and Department of Neurosurgery, Oslo University Hospital, Oslo, Norway. i.a.langmoen@medisin.uio.no.|SFI-CAST-Cancer Stem Cell Innovation Center, Oslo University Hospital, Oslo, Norway. i.a.langmoen@medisin.uio.no.|Norwegian Center for Stem Cell Research, Department of Immunology and Transfusion Medicine, Oslo University Hospital, Oslo, Norway. i.a.langmoen@medisin.uio.no.
authors: Iver A
authors: IA
authors: Langmoen
authors: Vilhelm Magnus Laboratory for Neurosurgical Research, Institute for Surgical Research and Department of Neurosurgery, Oslo University Hospital, Oslo, Norway. biljana.stangeland@labmed.uio.no.|SFI-CAST-Cancer Stem Cell Innovation Center, Oslo University Hospital, Oslo, Norway. biljana.stangeland@labmed.uio.no.
authors: Biljana
authors: B
authors: Stangeland
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D005909:Glioblastoma / Q000235:genetics* / Q000473:pathology; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000096:biosynthesis / Q000235:genetics*; D008297:Male; D051379:Mice; D063211:N-Terminal Acetyltransferase C / Q000096:biosynthesis* / Q000235:genetics; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D058953:Neural Stem Cells / Q000378:metabolism / Q000473:pathology; D011379:Prognosis; D012333:RNA, Messenger / Q000096:biosynthesis; D058570:TOR Serine-Threonine Kinases / Q000235:genetics*; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis / Q000235:genetics*; D023041:Xenograft Model Antitumor Assays
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009363:Neoplasm Proteins; D012333:RNA, Messenger; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D063211:N-Terminal Acetyltransferase C; C570950:NAA30 protein, human; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases