Adenoviral natural born killer gene therapy for malignant glioma.
Glioblastoma is a lethal neoplasm resistant to conventional radiotherapy and chemotherapy. Natural born killer (NBK), also known as Bcl-2-interacting killer (BIK), is a death-promoting Bcl-2 family protein sharing with Bcl-2 only the Bcl homology 3 (BH3) domain. We here report that an adenoviral vector encoding NBK (Ad-NBK) uniformly induces cell death in 12 human malignant glioma cell lines. Ad-NBK-induced cell death involves neither quantitative mitochondrial cytochrome c release nor caspase 8, 9, 7, or 3 processing and is unaffected by the viral caspase inhibitor, cytokine response modifier A (CRM-A), or selective caspase 8 or 9 inhibitors. In contrast, Ad-NBK-induced cell death is inhibited by the broad-range caspase inhibitor, zVAD-fmk, or by adenoviral gene transfer of the X-linked inhibitor of apoptosis protein (XIAP). Further, Ad-NBK-induced cell death is inhibited by Bcl-2 or Bcl-xL gene transfer. Interestingly, Bcl-2- and Bcl-xL-transfected glioma cells, which are partially protected from Ad-NBK-induced cell death, accumulate much higher levels of NBK than are ever observed in control-infected cells. This indicates that complex formation with Bcl-2 or Bcl-xL sequesters NBK in an inactive form and that free NBK, rather than an NBK-mediated depletion of free antiapoptotic Bcl-2 family proteins, is the proximate mediator of Ad-NBK-induced cell death. Conversely, proteasome inhibition-mediated accumulation of NBK strongly enhances Ad-NBK-induced cell death. Finally, Ad-NBK-infected LN-229 glioma cells are not tumorigenic in nude mice. Thus Ad-NBK triggers an XIAP- and zVAD-fmk-sensitive cell death pathway in glioma cells with potential therapeutic value, provided that NBK expression can be selectively targeted to cancer cells.
Naumann
Ulrike
U
Laboratory of Molecular Neuro-Oncology, Department of Neurology, University of Tübingen, School of Medicine, D-72076 Tübingen, Germany. ulrike.naumann@uni-teubingen.de
Schmidt
Friederike
F
Wick
Wolfgang
W
Frank
Brigitte
B
Weit
Simone
S
Gillissen
Bernd
B
Daniel
Peter
P
Weller
Michael
M
D000256:Adenoviridae / Q000235:genetics / Q000378:metabolism; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D051017:Apoptosis Regulatory Proteins; D015152:Blotting, Northern; D061945:Caspase Inhibitors; D045744:Cell Line, Tumor; D005470:Fluorometry; D015870:Gene Expression; D019254:Genes, bcl-2; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D005909:Glioblastoma / Q000235:genetics / Q000628:therapy*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D024101:Mitochondrial Proteins; D011233:Precipitin Tests; D011506:Proteins / Q000494:pharmacology; D051636:X-Linked Inhibitor of Apoptosis Protein
D000590:Amino Acid Chloromethyl Ketones; D051017:Apoptosis Regulatory Proteins; C096820:BIK protein, human; D061945:Caspase Inhibitors; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D011506:Proteins; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone