6533b85afe1ef96bd12b9643
RESEARCH PRODUCT
ΔNp73β is oncogenic in hepatocellular carcinoma by blocking apoptosis signaling via death receptors and mitochondria
Frank StaibVincenzo De LaurenziPeter H. KrammerAndreas TeufelGerry MelinoGerry MelinoSarah J. SeitzSnorri S. ThorgeirssonTobias SchillingMartina MüllerWolfgang StremmelAndré SchusterAndreas KochPeter R. Gallesubject
Gene isoformCarcinoma HepatocellularMolecular Sequence DataApoptosisBiologyModels BiologicalTransactivationDownregulation and upregulationCell Line TumorHumansProtein IsoformsMolecular BiologyTranscription factorGenes DominantOligonucleotide Array Sequence Analysisbcl-2-Associated X ProteinRegulation of gene expressionBase SequenceSettore BIO/11Gene Expression ProfilingTumor Suppressor ProteinsLiver NeoplasmsNuclear ProteinsTumor Protein p73PromoterReceptors Death DomainCell BiologyCell cyclePrognosisMitochondriaCell biologyDNA-Binding ProteinsEnzyme ActivationGene Expression Regulation NeoplasticDrug Resistance NeoplasmCaspasesCancer researchTumor Suppressor Protein p53Signal transductionPrecancerous ConditionsSignal TransductionDevelopmental Biologydescription
p73 belongs to the p53 family of transcription factors known to regulate cell cycle and apoptosis. The Trp73 gene has two promoters that drive the expression of two major p73 isoform subfamilies: TA and ΔN. In general, TAp73 isoforms show proapoptotic activities, whereas members of the N-terminally truncated (ΔN) p73 subfamily that lack the transactivation domain show antiapoptotic functions. We found that upregulation of ΔNp73 in hepatocellular carcinoma (HCC) correlated with reduced survival. Here, we investigated the molecular mechanisms accounting for the oncogenic role of ΔNp73 in HCC.ΔNp73β can directly interfere with the transcriptional activation function of the TA (containing the transactivation domain) isoforms of the p53 family and consequently inhibit transactivation of proapoptotic target genes. Interference of ΔNp73β with apoptosis-/chemosensitivity takes place at several levels of apoptosis signaling. ΔNp73β negatively regulates the genes encoding for the death receptors CD95, TNF-R1, TRAIL-R2 and TNFRSF18. Furthermore, ΔNp73β represses the genes encoding caspase-2, -3, -6, -8 and -9. Concomitantly, ΔNp73β inhibits apoptosis emanating from mitochondria.Thus, ΔNp73 expression in HCC selects against both the death receptor and the mitochondrial apoptosis activity of the TA isoforms. Our data suggest that ΔNp73 isoforms repress apoptosis-related genes of the extrinsic and intrinsic apoptosis signaling pathways thereby contributing to chemoresistance. The clinical importance of these data is evidenced by our finding that the ΔNp73ß target gene signature can predict the prognosis of patients suffering from HCC.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2010-07-01 | Cell Cycle |