title: Optimization of a synthetic beta-catenin-dependent promoter for tumor-specific cancer gene therapy.
abstract: We recently published the construction and evaluation of a beta-catenin-dependent, highly active promoter, CTP1, and its possible application for the treatment of colorectal cancer using gene-directed enzyme prodrug therapy with adenoviral (Ad) vectors. Alternative Ad-based approaches such as tumor-specific, replication-competent vectors and/or exploiting therapeutic gene products with intrinsic toxic activity, such as gibbon ape leukemia virus fusogenic membrane glycoprotein, diphtheria toxin A (DTA), and ricin, would demand a very tightly regulated promoter to avoid breakthrough replication and toxicity in nontumor tissue and Ad producer cell lines. In this study we optimized the activity/specificity profile of the synthetic beta-catenin-dependent promoter by varying its basal promoter, the number of Tcf binding sites, and the distance between these and the basal promoter. The optimal promoter, CTP4, showed virtually undetectable expression in cells with normal beta-catenin regulation but high level expression in cells deregulated for beta-catenin. Using CTP4 we were able to generate, for the first time to our knowledge, an Ad vector expressing fully active wild-type DTA without the need for time-consuming and cumbersome production systems. CTP4 should be the promoter of choice for Ad-based gene therapies of tumors deregulated for beta-catenin. We provide preliminary evidence that these may include prostate and ovarian as well as colorectal cancer.
authors.affiliation: ML Research, Keele University Science Park, Keele, Staffordshire ST5 5SP, UK. kai.lipinski@mlresearch.co.uk
authors.forename: Kai S
authors.initials: KS
authors.lastname: Lipinski
authors.forename: Hakim A
authors.initials: HA
authors.lastname: Djeha
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gawn
authors.forename: Suzanne
authors.initials: S
authors.lastname: Cliffe
authors.forename: Norman J
authors.initials: NJ
authors.lastname: Maitland
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Palmer
authors.forename: Andrew
authors.initials: A
authors.lastname: Mountain
authors.forename: Alistair S
authors.initials: AS
authors.lastname: Irvine
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Wrighton
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D001665:Binding Sites; D002277:Carcinoma / Q000737:chemistry / Q000378:metabolism; D045744:Cell Line, Tumor; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004167:Diphtheria Toxin / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics*; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000628:therapy*; D010051:Ovarian Neoplasms / Q000737:chemistry / Q000378:metabolism; D010446:Peptide Fragments / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011471:Prostatic Neoplasms / Q000737:chemistry / Q000378:metabolism; D016385:TATA Box / Q000235:genetics; D051820:TCF Transcription Factors; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D058118:Transcription Factor 7-Like 2 Protein; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D051176:beta Catenin
chemical_list: C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D004167:Diphtheria Toxin; D010446:Peptide Fragments; D051820:TCF Transcription Factors; C544894:TCF7L2 protein, human; D015534:Trans-Activators; D058118:Transcription Factor 7-Like 2 Protein; D014157:Transcription Factors; D051176:beta Catenin; C029795:diphtheria toxin fragment A