title: PKM2 promotes tumor angiogenesis by regulating HIF-1α through NF-κB activation.
abstract: BACKGROUND
  Initially identified as a molecule that regulates the final step of glycolysis, the M2 isoform of pyruvate kinase (PKM2) was recently reported to have a central role in the metabolic reprogramming of cancer cells as well as participating in cell cycle progression and gene transcription. Despite intensive efforts, the intricate molecular mechanisms through which PKM2 regulates tumor progression remain elusive.
  
  
  METHODS
  The proliferation and apoptosis of various pancreatic cancer cells using lentiviral-mediated PKM2 abrogation were assessed in vitro via Western blot and flow cytometric assay while the in vivo experiments involved tumor xenograft on chicken chorionallantoic membranes and immunohistochemistry on human tissue specimens. In order to decipher the molecular mechanism of HIF-1α and p65/RelA regulation by PKM2 in cancer cells cultivated in hypoxic atmosphere or normoxia we involved various biochemical assays such as Western blotting, immunoprecipitation, reporter gene assay and ELISA.
  
  
  RESULTS
  Strong expression of PKM2 was observed in 68 % of human pancreatic adenocarcinoma specimens and almost all analyzed pancreatic cancer cell lines. Abrogation of PKM2 resulted in impaired proliferation and augmented apoptosis in vitro as well as impaired tumor growth and decreased blood vessel formation in vivo. Furthermore, deletion of PKM2 negatively impacted hypoxia-induced HIF-1α accumulation and promoter activity ultimately resulting in impaired secretion of VEGF.
  
  
  CONCLUSIONS
  Our study suggests that in hypoxic pancreatic tumors PKM2 interferes both with NF-κB/p65 and HIF-1α activation that ultimately triggers VEGF-A secretion and subsequent blood vessel formation.
authors.affiliation: Center for Internal Medicine I, University of Ulm, Albert-Einstein-Allee 23, 89081, Ulm, Germany. ninel.azoitei@uni-ulm.de.
authors.forename: Ninel
authors.initials: N
authors.lastname: Azoitei
authors.affiliation: Center for Internal Medicine I, University of Ulm, Albert-Einstein-Allee 23, 89081, Ulm, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Becher
authors.affiliation: Gerhard-Domagk-Institute of Pathology, University of Münster, 48149, Münster, Germany.
authors.forename: Konrad
authors.initials: K
authors.lastname: Steinestel
authors.affiliation: Center for Internal Medicine III, University of Ulm, 89081, Ulm, Germany.
authors.forename: Arefeh
authors.initials: A
authors.lastname: Rouhi
authors.affiliation: Center for Internal Medicine I, University of Ulm, Albert-Einstein-Allee 23, 89081, Ulm, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Diepold
authors.affiliation: Institute of Pharmacology of Natural Products & Clinical Pharmacology, University of Ulm, 89081, Ulm, Germany.
authors.forename: Felicitas
authors.initials: F
authors.lastname: Genze
authors.affiliation: Institute of Pharmacology of Natural Products & Clinical Pharmacology, University of Ulm, 89081, Ulm, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Simmet
authors.affiliation: Center for Internal Medicine I, University of Ulm, Albert-Einstein-Allee 23, 89081, Ulm, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Seufferlein
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D017209:Apoptosis; D002352:Carrier Proteins / Q000378:metabolism*; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D002470:Cell Survival; D002645:Chickens; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008875:Middle Aged; D008954:Models, Biological; D016328:NF-kappa B / Q000378:metabolism*; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000098:blood supply* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D015398:Signal Transduction / Q000235:genetics; D013963:Thyroid Hormones / Q000378:metabolism*; D051996:Transcription Factor RelA / Q000378:metabolism; D014158:Transcription, Genetic; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D000097810:Thyroid Hormone-Binding Proteins
chemical_list: D002352:Carrier Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008565:Membrane Proteins; D016328:NF-kappa B; D013963:Thyroid Hormones; D051996:Transcription Factor RelA; D042461:Vascular Endothelial Growth Factor A; D000097810:Thyroid Hormone-Binding Proteins