title: Combination E2F-1 and p53 gene transfer does not enhance growth inhibition in human squamous cell carcinoma of the head and neck.
abstract: Ample data exist contending that wild-type p53 and E2F-1 cooperate to mediate apoptosis, that E2F-1-mediated apoptosis is p53 dependent in some situations, and that E2F-1 can induce accumulation of p53 in mammalian cells. These data support the investigation of the biological consequences of combined wild-typep53 and E2F-1 overexpression in human squamous cell carcinoma of the head and neck (SCCHN) for the purpose of developing apoptosis-inducing molecular intervention strategies for the management of this devastating disease. The recombinant adenovirus (Ad) vectors Ad-p53 and Ad-E2F-1 were used for wild-type p53 and E2F-1 gene transfers, respectively, into SCCHN cell lines TU138 and TU167. SCCHN cells transduced with either p53, E2F-1, or both underwent in vitro growth analysis, which revealed that simultaneous p53 and E2F-1 gene transfer did not result in enhanced growth inhibition. To explain our growth assay findings on the basis of potential negative molecular interactions between E2F-1 and p53, Western and Northern blotting analyses were performed to investigate the differential expression of the downstream p53-transactivated genes, p21Waf1 and BAX, under various p53 and E2F-1 gene transfer conditions. Whereas Western immunoblotting demonstrated that E2F-1 antagonized p53 induction of p21Waf1 and BAX, Northern blotting revealed that this interference was pretranslationally regulated and p53 dependent. Coimmunoprecipitation assay confirmed that the wild-type p53 and E2F-1 gene products formed protein-protein complexes in our cell lines. Our in vitro data demonstrated that in SCCHN, E2F-1 interferes with induction of p53-transactivated genes, probably through the formation of protein-protein complexes. Simultaneous p53 and E2F-1 gene transfer is not therapeutically advantageous in this in vitro model of SCCHN.
authors.affiliation: Department of Head and Neck Surgery, The University of Texas M.D. Anderson Cancer Center, Houston 77030, USA.
authors.forename: D K
authors.initials: DK
authors.lastname: Frank
authors.forename: T J
authors.initials: TJ
authors.lastname: Liu
authors.forename: M J
authors.initials: MJ
authors.lastname: Frederick
authors.forename: G L
authors.initials: GL
authors.lastname: Clayman
mesh_terms: D017209:Apoptosis / Q000502:physiology; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000502:physiology; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D015870:Gene Expression; D018014:Gene Transfer Techniques; D016158:Genes, p53; D006258:Head and Neck Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D011518:Proto-Oncogene Proteins / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D051028:bcl-2-Associated X Protein
chemical_list: C494826:BAX protein, human; C493956:CDKN1A protein, human; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein