Abstract
Two hepatocarcinoma cell lines, the Hepa-1 wild-type (c1c7) and the beta-subunit mutated (c4) lacking hypoxia-inducible factor-1 (HIF-1) activity, were differentially susceptible to apoptosis by hepatocyte growth factor (HGF). The c4 cells were 40% apoptotic 48 h after HGF treatment. On the contrary, the wild-type c1c7 cells showed modest signs of apoptosis only at 72 h. The revertant vT[2] cells, consisting of c4 cells stably transfected with HIF-1beta expression vector, behaved as the parental cells. To understand the mechanisms of this different sensitivity, we examined a panel of genes involved in apoptosis: ornithine decarboxylase, c-Myc and p53 protein levels progressively decreased while JNK1, caspase 8 and 3 activities persistently increased in c4 cells undergoing apoptosis. Distinct time-related events in c1c7 cells were the transient activations of JNK1 and caspase 8 followed by the accumulation of ODC and c-Myc proteins. The proapoptotic effect of HGF in c4 hepatocarcinoma cells seems to be related to HIF-1 deficiency with loss of cytoprotective and signalling functions. This may contribute to the triggering of the extrinsic pathway consisting in caspase 8 activation, which in turn causes BID cleavage and cytochrome c release. The effector caspase 3 is also activated.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Apoptosis*
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Blotting, Northern
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Blotting, Western
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Cadherins / metabolism
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Carcinoma, Hepatocellular / metabolism*
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Caspase 3
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Caspase 8
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Caspase 9
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Caspases / metabolism
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Cell Death
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Cytochrome c Group / metabolism
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DNA-Binding Proteins / genetics*
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DNA-Binding Proteins / physiology*
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Densitometry
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Enzyme Activation
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Genetic Vectors
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Hepatocyte Growth Factor / metabolism*
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Humans
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Hypoxia-Inducible Factor 1
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Hypoxia-Inducible Factor 1, alpha Subunit
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Mitochondria / metabolism
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Mitogen-Activated Protein Kinase 8
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Mitogen-Activated Protein Kinases / metabolism
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Mutation
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Nuclear Proteins / genetics*
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Nuclear Proteins / physiology*
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Proto-Oncogene Proteins c-met
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Proto-Oncogene Proteins*
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Receptors, Growth Factor*
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Scattering, Radiation
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Time Factors
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Trans-Activators / metabolism
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Transcription Factors*
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Tumor Cells, Cultured
Substances
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Cadherins
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Cytochrome c Group
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DNA-Binding Proteins
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HIF1A protein, human
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Hypoxia-Inducible Factor 1
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Hypoxia-Inducible Factor 1, alpha Subunit
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Nuclear Proteins
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Proto-Oncogene Proteins
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Receptors, Growth Factor
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Trans-Activators
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Transcription Factors
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Hepatocyte Growth Factor
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MET protein, human
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Proto-Oncogene Proteins c-met
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Mitogen-Activated Protein Kinase 8
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Mitogen-Activated Protein Kinases
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CASP3 protein, human
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CASP8 protein, human
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CASP9 protein, human
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Caspase 3
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Caspase 8
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Caspase 9
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Caspases