title: Inhibition of vascular endothelial growth factor A and hypoxia-inducible factor 1α maximizes the effects of radiation in sarcoma mouse models through destruction of tumor vasculature.
abstract: OBJECTIVE
  To examine the addition of genetic or pharmacologic inhibition of hypoxia-inducible factor 1α (HIF-1α) to radiation therapy (RT) and vascular endothelial growth factor A (VEGF-A) inhibition (ie trimodality therapy) for soft-tissue sarcoma.
  
  
  METHODS
  Hypoxia-inducible factor 1α was inhibited using short hairpin RNA or low metronomic doses of doxorubicin, which blocks HIF-1α binding to DNA. Trimodality therapy was examined in a mouse xenograft model and a genetically engineered mouse model of sarcoma, as well as in vitro in tumor endothelial cells (ECs) and 4 sarcoma cell lines.
  
  
  RESULTS
  In both mouse models, any monotherapy or bimodality therapy resulted in tumor growth beyond 250 mm(3) within the 12-day treatment period, but trimodality therapy with RT, VEGF-A inhibition, and HIF-1α inhibition kept tumors at <250 mm(3) for up to 30 days. Trimodality therapy on tumors reduced HIF-1α activity as measured by expression of nuclear HIF-1α by 87% to 95% compared with RT alone, and cytoplasmic carbonic anhydrase 9 by 79% to 82%. Trimodality therapy also increased EC-specific apoptosis 2- to 4-fold more than RT alone and reduced microvessel density by 75% to 82%. When tumor ECs were treated in vitro with trimodality therapy under hypoxia, there were significant decreases in proliferation and colony formation and increases in DNA damage (as measured by Comet assay and γH2AX expression) and apoptosis (as measured by cleaved caspase 3 expression). Trimodality therapy had much less pronounced effects when 4 sarcoma cell lines were examined in these same assays.
  
  
  CONCLUSIONS
  Inhibition of HIF-1α is highly effective when combined with RT and VEGF-A inhibition in blocking sarcoma growth by maximizing DNA damage and apoptosis in tumor ECs, leading to loss of tumor vasculature.
authors.affiliation: Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts; Division of Radiation Effects, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
authors.forename: Hae-June
authors.initials: HJ
authors.lastname: Lee
authors.affiliation: Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York.
authors.forename: Changhwan
authors.initials: C
authors.lastname: Yoon
authors.affiliation: Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York; Department of Surgery, Seoul National University Bundang Hospital, Sungnam, Korea.
authors.forename: Do Joong
authors.initials: DJ
authors.lastname: Park
authors.affiliation: Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Yeo-Jung
authors.initials: YJ
authors.lastname: Kim
authors.affiliation: Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Schmidt
authors.affiliation: Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts; Division of Radiation Effects, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
authors.forename: Yoon-Jin
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York.
authors.forename: William D
authors.initials: WD
authors.lastname: Tap
authors.affiliation: Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: T S Karin
authors.initials: TS
authors.lastname: Eisinger-Mathason
authors.affiliation: Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Edwin
authors.initials: E
authors.lastname: Choy
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina; Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina.
authors.forename: David G
authors.initials: DG
authors.lastname: Kirsch
authors.affiliation: Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Howard Hughes Medical Institute.
authors.forename: M Celeste
authors.initials: MC
authors.lastname: Simon
authors.affiliation: Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York. Electronic address: yoons@mskcc.org.
authors.forename: Sam S
authors.initials: SS
authors.lastname: Yoon
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000627:therapeutic use; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy / Q000379:methods; D004249:DNA Damage; D004317:Doxorubicin / Q000627:therapeutic use; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic / Q000235:genetics; D009389:Neovascularization, Pathologic / Q000628:therapy*; D034741:RNA, Small Interfering / Q000627:therapeutic use*; D011836:Radiation Tolerance; D011878:Radiotherapy; D012513:Sarcoma, Experimental / Q000098:blood supply* / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D016896:Treatment Outcome; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D000903:Antibiotics, Antineoplastic; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D034741:RNA, Small Interfering; D042461:Vascular Endothelial Growth Factor A; D004317:Doxorubicin