, Volume 9, Issue 3, pp 315–322 | Cite as

The viral death effector Apoptin reveals tumor-specific processes

  • J. L. Rohn
  • M. H. M. Noteborn


Several natural proteins, including the cellular protein TRAIL and the viral proteins E4orf4 and Apoptin, have been found to exert a tumor-preferential apoptotic activity. These molecules are potential anti-cancer agents with direct clinical applications. Also very intriguing is their possible utility as sensors of the tumorigenic phenotype. Here, we focus on Apoptin, discussing recent research that has greatly increased our understanding of its tumor-specific processes. Apoptin, which kills tumor cells in a p53- and Bcl-2-independent, caspase-dependent manner, is biologically active as a highly stable, multimeric complex consisting of 30 to 40 monomers that form distinct superstructures upon binding cooperatively to DNA. In tumor cells, Apoptin is imported into the nucleus prior to the induction of apoptosis; this contrasts with the situation in primary or low-passage normal cell cultures where nuclear translocation of Apoptin is rare and inefficient. Apoptin contains two autonomous death-inducing domains, both of which exhibit a strong correlation between nuclear localization and killing activity. Nevertheless, forced nuclear localization of Apoptin in normal cells is insufficient to allow induction of apoptosis, indicating that another activation step particular to the tumor or transformed state is required. Indeed, a kinase activity present in cancer cells but negligible in normal cells was recently found to regulate the activity of Apoptin by phosphorylation. However, in normal cells, Apoptin can be activated by transient transforming signals conferred by ectopically expressed SV40 LT antigen, which rapidly induces Apoptin’s phosphorylation, nuclear accumulation and the ability to induce apoptosis. The region on LT responsible for conferring this effect has been mapped to the N-terminal J domain. In normal cells that do not receive such signals, Apoptin becomes aggregated, epitope-shielded and is eventually degraded in the cytoplasm. Finally, Apoptin interacts with various partners of the human proteome including DEDAF, Nmi and Hippi, which may help to regulate either Apoptin’s activation or execution processes. Taken together, these recent advances illustrate that elucidating the mechanism of Apoptin-induced apoptosis can lead to the discovery of novel tumor-specific pathways that may be exploitable as anti-cancer drug targets.

Apoptin DEDAF drug targets Hippi epitope shielding Nmi nuclear localization SV40 LT antigen tumor-specific apoptosis tumor-specific kinase activity 


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  1. 1.
    MacFarlane M. TRAIL-induced signaling and apoptosis. Toxicol Lett 2003; 139: 89–97.PubMedGoogle Scholar
  2. 2.
    Branton PE, Roopchand DE. The role of adenovirus E4orf4 protein in viral replication and cell killing. Oncogene 2001; 20: 7855–7865.PubMedGoogle Scholar
  3. 3.
    Noteborn MHM. Apoptin as an anticancer therapy. In: La Thangue NB and Bandara LR eds. Targets for Cancer Chemotherapy; Transcription Factors and Other Nuclear Proteins. Humana Press Inc., Totowa, New Jersey, USA, 2002, pp. 275–287.Google Scholar
  4. 4.
    Noteborn MHM. Apoptin-induced apoptosis: A review. Apoptosis 1999; 4: 317–319.PubMedGoogle Scholar
  5. 5.
    Ray S, Almasan A. Apoptosis induction in prostate cancer cells and xenografts by combined treatment with Apo2 ligand/tumor necrosis factor-related apoptosis-inducing ligand and CPT-11. Cancer Res 2003; 63: 4713–4723.PubMedGoogle Scholar
  6. 6.
    Van der Eb MM, Pietersen Am, Speetjens F, et al. Gene therapy with Apoptin induces regression of xenografted human hepatomas. Cancer Gene Ther 2002; 9; 53–61.CrossRefPubMedGoogle Scholar
  7. 7.
    Shen Z, Wang Y, Zong Y, Qu S. Experimental study on the antitumor effect of chicken anemia virus vp3 gene against liver carcinoma in vivo. Huazhong Uni Sci Technolog Med Sci 2003; 23: 105–115.Google Scholar
  8. 8.
    Ashkenazi A. Targeting death and decoy receptors of the tumour necrosis factor superfamily. Nat Rev Cancer 2002; 2: 420–430.CrossRefPubMedGoogle Scholar
  9. 9.
    LeBlanc HN, Asjkenazi A. Apo2L/TRAIL and its death and decoy receptors. Cell Death Diff 2003; 10: 66–75.PubMedGoogle Scholar
  10. 10.
    Greil R, Anether G, Johrere K, Tinhofer I. Tracking death dealing by Fas and TRAIL in lymphatic neoplastic disorders: Pathways, targets, and therapeutic tools. J Leukocyte Biol 2003; 74: 311–339.PubMedGoogle Scholar
  11. 11.
    Robert A, Miron M-J, Champagne C, Gingras M-C, Branton PE, Lavoie JN. Distinct cell death pathways triggered by the adenovirus early region 4 ORF 4 protein. J Cell Biol 2002; 158: 519–528.PubMedGoogle Scholar
  12. 12.
    Marcellus RC, Chan H, Paquette D, Thirlwell S, Boivin D, Branton PE. Induction of p53–independent apoptosis by the adenovirus E4orf4 protein requires binding to the Bα subunit of protein phosphatase 2A. J. Virol 2000; 74: 7869–7877.PubMedGoogle Scholar
  13. 13.
    Van Hoof C, Goris J. Phosphatases in apoptosis: To be or not to be, PP2A is in the heart of the question. Biochim Biophys Acta 2003; 1640: 97–104.PubMedGoogle Scholar
  14. 14.
    Noteborn MHM, Danen-van Oorschot AAAM, Van der Eb AJ. Chicken anemia virus: Induction of apoptosis by a single protein of a single-stranded DNA virus. Sem Virol 1998; 8: 497–504.Google Scholar
  15. 15.
    Danen-van Oorschot AAAM. Apoptin, a viral protein that induces tumor-specific apoptosis. Thesis, Leiden University, Leiden, The Netherlands, 2001.Google Scholar
  16. 16.
    Ferreira CG, Epping M, Kruyr FAE, Giaccone G. Apoptosis: Target of cancer therapy. Clin Cancer Res 2002; 8: 2024–2034.PubMedGoogle Scholar
  17. 17.
    Danen-van Oorschot AAAM, Van der Eb AJ, Noteborn MHM. The chicken anemia virus-derived protein Apoptin requires activation of caspases for induction of apoptosis in human tumor cells. J Virol 2000; 74: 7072–7078.PubMedGoogle Scholar
  18. 18.
    Noteborn MHM, Van der Eb AJ. Apoptin induces apoptosis in transformed cells specifically: Potentials for an anti-tumor therapy. Biogenic Amines 1999; 15: 73–91.Google Scholar
  19. 19.
    Danen-van Oorschot AAAM, Den Hollander A, Takayama S, Reed J, Van der Eb AJ, Noteborn MHM. BAG-1 inhibits p53–induced but not Apoptin-induced apoptosis. Apoptosis 1997; 2: 395–402.PubMedGoogle Scholar
  20. 20.
    Danen-van Oorschot AAAM, Zhang, Y-H, Erkeland S, Fischer DF, Van der Eb AJ, Noteborn MHM. The effect of Bcl-2 on Apoptin in normal cells versus transformed human cells. Leukemia 1999; 13: S75–S77.PubMedGoogle Scholar
  21. 21.
    Schoop RAL, Kooistra K, Baatenburg de Jong RJ, Noteborn MHM. Bcl-X1 inhibits p53 but not Apoptin-induced apoptosis. Int J Cancer, in press.Google Scholar
  22. 22.
    Leliveld SR, Noteborn MHM, Abrahams JP. Prevalent conformations and subunit exchange in the biologically active Apoptin protein multimer. Eur J Biochem 2003; 270: 3619–3627.PubMedGoogle Scholar
  23. 23.
    Leliveld SR, Zhang Y-H, Rohn JL, Noteborn MHM, Abrahams JP. Apoptin induces tumor-specific apoptosis as a globular multimer. J Biol Chem 2003; 278: 9042–9051.PubMedGoogle Scholar
  24. 24.
    Zhang Y-H, Leliveld SR, Kooistra K, et al. Recombinannt Apoptin multimers kill tumor cells but are non-toxic and epitope-shielded in a normal-cell-specific fashion. Exp Cell Res 2003; 289: 36–46.PubMedGoogle Scholar
  25. 25.
    Danen-Van Oorschot AAAM, Fischer D, Grimbergen JM, et al. Apoptin induces apoptosis in human transformed and malignant cells but not in normal cells. Proc Natl Acad Sci USA 1997; 94: 5843–5847.PubMedGoogle Scholar
  26. 26.
    Leliveld SR, Dame RT, Mommaas MA, et al. Apoptin protein multimers form distinct higher-order nucleoprotein complexes with DNA. Nucleic Acid Res 2003; 31: 4805–4813.PubMedGoogle Scholar
  27. 27.
    Danen-van Oorschot AAAM, Zhang Y-H, Leliveld SR, et al. Importance of nuclear localization of Apoptin for tumor-specific induction of apoptosis. J Biol Chem 2003; 278: 27729–27736.PubMedGoogle Scholar
  28. 28.
    Guelen L, Paterson H, Gaeken J, Meyers M, Fatzaneh F, Tavassoli M. TAT-Apoptin is efficiently delivered and induces apoptosis in cancer cells. Oncogene, in press.Google Scholar
  29. 29.
    Snyder EL, Dowdy SF. Protein/peptide transduction domains: potential to deliver larger DNA molecules into cells. Curr Opin Mol Ther 2001; 3: 147–152.PubMedGoogle Scholar
  30. 30.
    Alvarez M, Rhodes S, Bidwell JP. Context-dependent transcription: all politics are local. Gene 2003; 313: 43–57.PubMedGoogle Scholar
  31. 31.
    Bao J, Zervs AS. Isolation and characterization of Nmi, a novel partner of Myc proteins. Oncogene 1996; 16: 2171–2176.Google Scholar
  32. 32.
    Sun GJ, Tong X, Dong Y, Mei ZZ, Sun ZX. Identification of a protein interacting with Apoptin from human leucocyte cDNA library by using yeast two-hybrid screening. Sheng Wu Hua Xue Sheng Wu Wu Li Xue Bao (Shanghai) 2002; 34: 369–372.Google Scholar
  33. 33.
    Pelengaris S, Khan M, Evan G. c-Myc: More than just a matter of life and death. Nat Rev Cancer 2002; 2: 764–776.PubMedGoogle Scholar
  34. 34.
    Danen-van Oorschot AAAM, Voskamp P, Seelen MCMJ, et al. Human death effector domain-associated factor interacts with the viral apoptosis agonist Apoptin and exerts tumor-preferential cell killing. Submitted.Google Scholar
  35. 35.
    Cheng C-H, Chen D-Y, Lin Y-M, You C-Y. Cloning and characterization of the Apoptin-associated proteins. Proc 14th Joint Ann Conf Biomed Sci Taipei Taiwan, 1999.Google Scholar
  36. 36.
    Zheng L, Schickling O, Peter ME, Leonardo MJ. The death effector domain-associated factor plays distinct regulatory roles in the nucleus and cytoplasm. J Biol Chem 2001; 276: 31945–31952.PubMedGoogle Scholar
  37. 37.
    Shickling O, Stegh AH, Byrd J, Peter M. Nuclear localization of DEDD leads to caspase-6 activation through its death effector domain and inhibition of RNA polymerase I dependent transcription. Cell Death Diff 2001; 8: 1157–1168.Google Scholar
  38. 38.
    Stegh AH, Schickling O, Ehret A, et al. DEDD, a novel death effector domain-containing protein, targeted to the nucleolus. EMBO J 1998; 17: 5974–5986.PubMedGoogle Scholar
  39. 39.
    Chan EK, Imai H, Hamel JC, Tan EM. Human autoantibody to RNA polymerase I transcription factor hUBF. Molecular identity of nucleolus organizer region autoantigen NOR-90 and ribosomal RNA transcription upstream binding factor. J Exp Med 1991; 174: 1239–1244.PubMedGoogle Scholar
  40. 40.
    Schlesio S, Halperin T, Vidal M, Nevins JR. Interaction of YY1 with E2Fs, mediated by RYBP, provides a mechanism for specificity of E2F function. EMBO J 2002; 21: 5775–5786.PubMedGoogle Scholar
  41. 41.
    Cheng C-M, Huang S-p, Chang Y-F, Chung W-Y, You C-Y. The viral death protein Apoptin interacts with Hippi, the protein interactor of Huntingtin-interacting protein 1. Biochim Biophys Res Com 2003: 305: 359–364.Google Scholar
  42. 42.
    Gervais FG, Singaraja R, Xanthoudakis S, et al. Recruitment and activation of caspase-8 by the Huntingtin-interacting protein Hip-1 and a novel partner Hippi. Nat Cell Biol 2002; 4: 95–105.PubMedGoogle Scholar
  43. 43.
    Rohn JL, Zhang Y-H, Aalbers RIJM, et al. A tumor-specific kinase activity regulates the viral death protein Apoptin. J Biol Chem 2002; 277: 50820–50827.PubMedGoogle Scholar
  44. 44.
    Peters MA, Jackson DC, Crabb BS, Browning GF. Chicken anemia virus VP2 is a novel dual specificity protein phosphatase. J Biol Chem 2002; 277: 39566–39573.PubMedGoogle Scholar
  45. 45.
    Zhang Y-H, Abrahams PJ, Van der Eb AJ, Noteborn MHM. The viral protein Apoptin induces apoptosis in UV-C-irradiated cells from individuals with various hereditary cancer-prone syndromes. Cancer Res. 1999; 59: 3010–3015.PubMedGoogle Scholar
  46. 46.
    Zhang Y-H, Kooistra K, Pietersen AM, Rohn JL, Noteborn MHM. Activation of the tumor-specific death effector Apoptin and its kinase by an N-terminal determinan of SV40 large T antigen Submitted.Google Scholar
  47. 47.
    Lu Y, Lian H, Sharma P, et al. Disruption of the cockayne syndrome B gene impairs spontaneous tumorigenesis in cancer-predisposed Ink4a/ARF knockout mice. Mol Cell Biol 2001; 21: 1810–1818.PubMedGoogle Scholar
  48. 48.
    Zhang Y-H. Activation of Apoptin, a tumor-specific viral death effector. Thesis, Leiden University, The Netherlands, 2004.Google Scholar
  49. 49.
    Pietersen AM. Preclinical studies with Apoptin. Thesis, Erasmus University, Rotterdam, The Netherlands, 2003.Google Scholar

Copyright information

© Kluwer Academic Publishers 2004

Authors and Affiliations

  1. 1.Leiden Institute of ChemistryLeiden UniversityLeidenThe Netherlands

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