title: Sensitivity of cancer cells to truncated diphtheria toxin.
abstract: BACKGROUND
  Diphtheria toxin (DT) has been utilized as a prospective anti-cancer agent for the targeted delivery of cytotoxic therapy to otherwise untreatable neoplasia. DT is an extremely potent toxin for which the entry of a single molecule into a cell can be lethal. DT has been targeted to cancer cells by deleting the cell receptor-binding domain and combining the remaining catalytic portion with targeting proteins that selectively bind to the surface of cancer cells. It has been assumed that "receptorless" DT cannot bind to and kill cells. In the present study, we report that "receptorless" recombinant DT385 is in fact cytotoxic to a variety of cancer cell lines.
  
  
  METHODS
  In vitro cytotoxicity of DT385 was measured by cell proliferation, cell staining and apoptosis assays. For in vivo studies, the chick chorioallantoic membrane (CAM) system was used to evaluate the effect of DT385 on angiogenesis. The CAM and mouse model system was used to evaluate the effect of DT385 on HEp3 and Lewis lung carcinoma (LLC) tumor growth, respectively.
  
  
  RESULTS
  Of 18 human cancer cell lines tested, 15 were affected by DT385 with IC(50) ranging from 0.12-2.8 microM. Furthermore, high concentrations of DT385 failed to affect growth arrested cells. The cellular toxicity of DT385 was due to the inhibition of protein synthesis and induction of apoptosis. In vivo, DT385 diminished angiogenesis and decreased tumor growth in the CAM system, and inhibited the subcutaneous growth of LLC tumors in mice.
  
  
  CONCLUSIONS
  DT385 possesses anti-angiogenic and anti-tumor activity and may have potential as a therapeutic agent.
authors.affiliation: Departments of Biochemistry and Molecular Biology and Pathology, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wendy
authors.initials: W
authors.lastname: Schulte
authors.forename: Desmond
authors.initials: D
authors.lastname: Pink
authors.forename: Kyle
authors.initials: K
authors.lastname: Phipps
authors.forename: Andries
authors.initials: A
authors.lastname: Zijlstra
authors.forename: John D
authors.initials: JD
authors.lastname: Lewis
authors.forename: David Morton
authors.initials: DM
authors.lastname: Waisman
mesh_terms: D000818:Animals; D002417:Cattle; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002642:Chick Embryo; D049033:Chorioallantoic Membrane / Q000187:drug effects / Q000378:metabolism; D004167:Diphtheria Toxin / Q000494:pharmacology*; D004705:Endocytosis / Q000187:drug effects; D006801:Humans; D051379:Mice; D050505:Mutant Proteins / Q000494:pharmacology*; D009369:Neoplasms / Q000098:blood supply / Q000473:pathology*; D009389:Neovascularization, Pathologic / Q000378:metabolism / Q000473:pathology; D014176:Protein Biosynthesis / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D004167:Diphtheria Toxin; D050505:Mutant Proteins
references.citation: EMBO J. 1994 May 15;13(10):2322-30
references.pmid: 8194524
references.citation: Protein Sci. 1993 Feb;2(2):292-8
references.pmid: 8443606
references.citation: EMBO J. 1998 Jan 15;17(2):615-25
references.pmid: 9430652
references.citation: Leuk Lymphoma. 1993 Oct;11(3-4):249-62
references.pmid: 7505148
references.citation: Cell. 1992 Jun 12;69(6):1051-61
references.pmid: 1606612
references.citation: Cancer Cell. 2008 Mar;13(3):221-34
references.pmid: 18328426
references.citation: J Biol Chem. 1973 Jan 25;248(2):654-8
references.pmid: 4346341
references.citation: Anat Embryol (Berl). 1975 Aug 9;147(2):127-32
references.pmid: 1237240
references.citation: Clin Cancer Res. 2002 Jun;8(6):1740-6
references.pmid: 12060611
references.citation: Leuk Lymphoma. 2004 Aug;45(8):1647-56
references.pmid: 15370220
references.citation: Infect Immun. 1981 May;32(2):575-82
references.pmid: 7251138
references.citation: Exp Hematol. 2000 Dec;28(12):1390-400
references.pmid: 11146161
references.citation: Cell. 1978 Sep;15(1):245-50
references.pmid: 699044
references.citation: J Biol Chem. 1971 Jul 10;246(13):4251-60
references.pmid: 4326212
references.citation: Protein Expr Purif. 2004 Jan;33(1):123-33
references.pmid: 14680969
references.citation: Biochemistry. 2001 Nov 6;40(44):13246-53
references.pmid: 11683633
references.citation: FASEB J. 2000 Jul;14(10):1389-99
references.pmid: 10877832
references.citation: Cancer Res. 1996 Mar 15;56(6):1324-30
references.pmid: 8640821
references.citation: Curr Top Microbiol Immunol. 1992;175:1-26
references.pmid: 1378368
references.citation: Future Oncol. 2008 Aug;4(4):457-69
references.pmid: 18684057
references.citation: Clin Cancer Res. 2006 Feb 15;12(4):1284-91
references.pmid: 16489085
references.citation: Blood. 1996 Aug 15;88(4):1445-56
references.pmid: 8695865
references.citation: Breast Cancer Res Treat. 2004 May;85(2):161-71
references.pmid: 15111774
references.citation: Expert Rev Anticancer Ther. 2007 Jan;7(1):11-7
references.pmid: 17187516
references.citation: J Biol Chem. 2004 Jun 25;279(26):27633-45
references.pmid: 15066996
references.citation: Toxicol Appl Pharmacol. 1999 Jul 15;158(2):152-60
references.pmid: 10406930
references.citation: Bacteriol Rev. 1975 Mar;39(1):54-85
references.pmid: 164179
references.citation: J Natl Cancer Inst. 1989 Oct 4;81(19):1455-63
references.pmid: 2550658
references.citation: Cancer Res. 2003 Sep 15;63(18):5866-73
references.pmid: 14522911
references.citation: Int J Cancer. 2005 May 10;114(6):870-8
references.pmid: 15609296
references.citation: Proc Natl Acad Sci U S A. 2002 Jan 22;99(2):832-7
references.pmid: 11792868
references.citation: J Biol Chem. 1990 Nov 25;265(33):20673-7
references.pmid: 2243114
references.citation: Nat Med. 2006 Mar;12(3):354-60
references.pmid: 16501571
references.citation: N Engl J Med. 1971 Nov 18;285(21):1182-6
references.pmid: 4938153
references.citation: J Cell Sci. 1989 May;93 ( Pt 1):53-61
references.pmid: 2613759
references.citation: Leuk Res. 2003 Jan;27(1):79-84
references.pmid: 12479856
references.citation: AAPS J. 2006 Aug 18;8(3):E532-51
references.pmid: 17025272
references.citation: Leukemia. 2003 Jan;17(1):155-9
references.pmid: 12529673
references.citation: Leukemia. 1999 Apr;13(4):629-33
references.pmid: 10214872
references.citation: Proc Natl Acad Sci U S A. 1986 Nov;83(21):8258-62
references.pmid: 3095831