title: Endothelial membrane remodeling is obligate for anti-angiogenic radiosensitization during tumor radiosurgery.
abstract: While there is significant interest in combining anti-angiogenesis therapy with conventional anti-cancer treatment, clinical trials have as of yet yielded limited therapeutic gain, mainly because mechanisms of anti-angiogenic therapy remain to a large extent unknown. Currently, anti-angiogenic tumor therapy is conceptualized to either "normalize" dysfunctional tumor vasculature, or to prevent recruitment of circulating endothelial precursors into the tumor. An alternative biology, restricted to delivery of anti-angiogenics immediately prior to single dose radiotherapy (radiosurgery), is provided in the present study.
  
  
  
  Genetic data indicate an acute wave of ceramide-mediated endothelial apoptosis, initiated by acid sphingomyelinase (ASMase), regulates tumor stem cell response to single dose radiotherapy, obligatory for tumor cure. Here we show VEGF prevented radiation-induced ASMase activation in cultured endothelium, occurring within minutes after radiation exposure, consequently repressing apoptosis, an event reversible with exogenous C(16)-ceramide. Anti-VEGFR2 acts conversely, enhancing ceramide generation and apoptosis. In vivo, MCA/129 fibrosarcoma tumors were implanted in asmase(+/+) mice or asmase(-/-) littermates and irradiated in the presence or absence of anti-VEGFR2 DC101 or anti-VEGF G6-31 antibodies. These anti-angiogenic agents, only if delivered immediately prior to single dose radiotherapy, de-repressed radiation-induced ASMase activation, synergistically increasing the endothelial apoptotic component of tumor response and tumor cure. Anti-angiogenic radiosensitization was abrogated in tumors implanted in asmase(-/-) mice that provide apoptosis-resistant vasculature, or in wild-type littermates pre-treated with anti-ceramide antibody, indicating that ceramide is necessary for this effect.
  
  
  
  These studies show that angiogenic factors fail to suppress apoptosis if ceramide remains elevated while anti-angiogenic therapies fail without ceramide elevation, defining a ceramide rheostat that determines outcome of single dose radiotherapy. Understanding the temporal sequencing of anti-angiogenic drugs and radiation enables optimized radiosensitization and design of innovative radiosurgery clinical trials.
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America.
authors.forename: Jean-Philip
authors.initials: JP
authors.lastname: Truman
authors.forename: Mónica
authors.initials: M
authors.lastname: García-Barros
authors.forename: Matthew
authors.initials: M
authors.lastname: Kaag
authors.forename: Dolores
authors.initials: D
authors.lastname: Hambardzumyan
authors.forename: Branka
authors.initials: B
authors.lastname: Stancevic
authors.forename: Michael
authors.initials: M
authors.lastname: Chan
authors.forename: Zvi
authors.initials: Z
authors.lastname: Fuks
authors.forename: Richard
authors.initials: R
authors.lastname: Kolesnick
authors.forename: Adriana
authors.initials: A
authors.lastname: Haimovitz-Friedman
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D016923:Cell Death / Q000187:drug effects / Q000528:radiation effects; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002518:Ceramides / Q000378:metabolism; D042783:Endothelial Cells / Q000473:pathology*; D004789:Enzyme Activation / Q000187:drug effects / Q000528:radiation effects; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D006801:Humans; D051379:Mice; D009369:Neoplasms / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D009389:Neovascularization, Pathologic / Q000188:drug therapy*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology* / Q000627:therapeutic use; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000276:immunology / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D002518:Ceramides; C511761:DC101 monoclonal antibody; D011838:Radiation-Sensitizing Agents; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2; D013108:Sphingomyelin Phosphodiesterase
references.citation: Proc Natl Acad Sci U S A. 2007 Jun 19;104(25):10625-30
references.pmid: 17553957
references.citation: Cancer Cell. 2004 Dec;6(6):553-63
references.pmid: 15607960
references.citation: Curr Top Microbiol Immunol. 1999;237:1-30
references.pmid: 9893343
references.citation: N Engl J Med. 2008 May 8;358(19):2039-49
references.pmid: 18463380
references.citation: Oncogene. 2003 Aug 21;22(35):5457-70
references.pmid: 12934106
references.citation: Cancer Res. 2001 Mar 15;61(6):2413-9
references.pmid: 11289107
references.citation: Nat Med. 2004 Feb;10(2):155-60
references.pmid: 14704790
references.citation: Chem Phys Lipids. 1999 Nov;102(1-2):123-30
references.pmid: 11001566
references.citation: J Biol Chem. 2005 Jul 15;280(28):26425-34
references.pmid: 15849201
references.citation: Cancer Res. 2000 Jan 15;60(2):321-7
references.pmid: 10667583
references.citation: Int J Radiat Oncol Biol Phys. 2008 Jun 1;71(2):484-90
references.pmid: 18234445
references.citation: Cell. 1994 Sep 23;78(6):1005-15
references.pmid: 7923351
references.citation: Cancer Res. 1998 May 15;58(10):2260-4
references.pmid: 9605775
references.citation: Nat Clin Pract Oncol. 2008 Jul;5(7):378-91
references.pmid: 18560389
references.citation: J Biol Chem. 2001 Jun 29;276(26):23954-61
references.pmid: 11287428
references.citation: Int J Radiat Oncol Biol Phys. 2008 Mar 1;70(3):804-15
references.pmid: 18191336
references.citation: Mol Hum Reprod. 2001 Aug;7(8):771-7
references.pmid: 11470865
references.citation: Cancer Cell. 2005 Aug;8(2):89-91
references.pmid: 16098459
references.citation: J Biol Chem. 2001 Jun 8;276(23):20589-96
references.pmid: 11279185
references.citation: Science. 2001 Jul 13;293(5528):293-7
references.pmid: 11452123
references.citation: Cancer Res. 1991 May 15;51(10):2552-8
references.pmid: 2021936
references.citation: Science. 2003 May 16;300(5622):1155-9
references.pmid: 12750523
references.citation: Am J Physiol. 1994 Jan;266(1 Pt 2):F81-8
references.pmid: 8304487
references.citation: Cancer Res. 1999 Oct 15;59(20):5194-201
references.pmid: 10537297
references.citation: Oncogene. 2003 Oct 13;22(45):7070-7
references.pmid: 14557812
references.citation: Cell. 1996 Jul 26;86(2):189-99
references.pmid: 8706124
references.citation: Life Sci. 2003 Apr 18;72(22):2473-9
references.pmid: 12650855
references.citation: Cancer Res. 2004 May 15;64(10):3593-8
references.pmid: 15150117
references.citation: J Biol Chem. 2007 Apr 13;282(15):11549-61
references.pmid: 17303575
references.citation: Int J Radiat Oncol Biol Phys. 2009 Jan 1;73(1):112-8
references.pmid: 18786780
references.citation: Microvasc Res. 2007 Sep-Nov;74(2-3):72-84
references.pmid: 17560615
references.citation: Cell Death Differ. 2000 May;7(5):413-24
references.pmid: 10800075
references.citation: Nat Genet. 1995 Jul;10(3):288-93
references.pmid: 7670466
references.citation: N Engl J Med. 1971 Nov 18;285(21):1182-6
references.pmid: 4938153
references.citation: J Exp Med. 1997 Dec 1;186(11):1831-41
references.pmid: 9382882
references.citation: Cancer Metastasis Rev. 1998 Jun;17(2):155-61
references.pmid: 9770111
references.citation: J Mol Med (Berl). 2004 Jun;82(6):357-63
references.pmid: 15069600
references.citation: Cancer Res. 1986 Mar;46(3):1120-3
references.pmid: 3943089
references.citation: Oncogene. 2003 Sep 1;22(37):5897-906
references.pmid: 12947396