Herpes simplex virus thymidine kinase/ganciclovir-induced apoptosis involves ligand-independent death receptor aggregation and activation of caspases.
Suicide gene therapy systems such as the herpes simplex thymidine kinase/ganciclovir system (TK/GCV) may kill cancer cells by apoptosis through as yet undefined mechanisms. Here we show that TK/GCV treatment induces p53 accumulation and increases cell surface expression of CD95 and tumor necrosis factor receptor, which is likely to involve p53-mediated translocation of CD95 to the cell surface. TK/GCV-induced apoptosis involves CD95-L-independent CD95 aggregation leading to the formation of a Fas-associated death domain protein (FADD) and caspase-8-containing, death-inducing signaling complex. Dominant negative FADD, the caspase-8 inhibitor zIETD-fmk [Z-Ile-Glu(OMe)-Thr-Asp(OMe)-fluoromethylketone], and zVAD-fmk (Z-Val-Ala-Asp-fluoromethylketone) partially abrogate TK/GCV-induced apoptosis. In addition to apoptosis induction, TK/GCV treatment strongly sensitizes for CD95-L-, TNF-, and TNF-related, apoptosis-inducing, ligand (TRAIL)-induced cell death in constitutively resistant cells. These findings may be used to increase the efficacy of TK/GCV and other suicide gene therapy systems for the treatment of cancer.
Universitäts-Kinderklinik, 89075 Ulm, Germany.
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C
Beltinger
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Fulda
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Kammertoens
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E
Meyer
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Uckert
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KM
Debatin
D048868:Adaptor Proteins, Signal Transducing; D000998:Antiviral Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D020126:Brefeldin A / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism; D020169:Caspases / Q000378:metabolism*; D004789:Enzyme Activation; D053222:Fas Ligand Protein; D053200:Fas-Associated Death Domain Protein; D015774:Ganciclovir / Q000494:pharmacology; D015316:Genetic Therapy / Q000379:methods; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D018139:Simplexvirus / Q000201:enzymology*; D053221:TNF-Related Apoptosis-Inducing Ligand; D013937:Thymidine Kinase / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D000998:Antiviral Agents; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; C505533:FADD protein, human; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D053200:Fas-Associated Death Domain Protein; D008562:Membrane Glycoproteins; D011480:Protease Inhibitors; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D016159:Tumor Suppressor Protein p53; D020126:Brefeldin A; D013937:Thymidine Kinase; D020169:Caspases; D015774:Ganciclovir