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Two-step amplification of the human PPT sequence provides specific gene expression in an immunocompetent murine prostate cancer model
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Clinical Immunology. (KITM)
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Clinical Immunology. (KITM)
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Clinical Immunology. (KITM)
2007 (English)In: Cancer Gene Therapy, ISSN 0929-1903, E-ISSN 1476-5500, Vol. 14, no 3, 233-240 p.Article in journal (Refereed) Published
Abstract [en]

The recombinant prostate-specific PPT sequence comprises a prostate-specific antigen enhancer, a PSMA enhancer and a TARP promoter. It is transcriptionally active in human prostate cancer cells both in the presence and absence of testosterone. However, in experimental murine prostate cancer, it has no detectable transcriptional activity. Herein, we describe that the PPT sequence in combination with a two-step transcriptional amplification (TSTA) system becomes active also in murine prostate cancer cells. An adenovirus with TSTA-amplified PPT-controlled expression of the luciferase reporter gene, Ad[PPT/TSTA-Luc], has up to 100-fold higher prostate-specific transcriptional activity than a non-amplified PPT-based adenovirus, Ad[PPT-Luc], in human cells. In addition, Ad[PPT/TSTA-Luc] confers prostate-specific transgene expression in murine cells, with an activity that is approximately 23% of Ad[CMV-Luc] in the transgenic adenocarcinoma of the mouse prostate (TRAMP)-C2 cells. Moreover, to visualize luciferase expression in living mice a charge-coupled device camera was used. Ad[PPT/TSTA-Luc] yielded approximately 30-fold higher transgene expression than Ad[PPT-Luc] in LNCaP tumor xenografts. Importantly, Ad[PPT/TSTA-Luc] also showed activity in murine TRAMP-C2 tumors, whereas Ad[PPT-Luc] activity was undetectable. These results highlight that the recombinant PPT sequence is active in murine prostate cancer cells when augmented by a TSTA system. This finding opens up for preclinical studies with prostate-specific therapeutic gene expression in immunocompetent mice.

Place, publisher, year, edition, pages
2007. Vol. 14, no 3, 233-240 p.
Keyword [en]
PPT, TSTA, adenovirus, prostate cancer, promoter
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-95731DOI: 10.1038/sj.cgt.7701007ISI: 000244207600002PubMedID: 17053814OAI: oai:DiVA.org:uu-95731DiVA: diva2:170055
Available from: 2007-04-12 Created: 2007-04-12 Last updated: 2011-02-14Bibliographically approved
In thesis
1. Adenovirus-mediated CD40 Ligand Immunotherapy of Prostate and Bladder Cancer
Open this publication in new window or tab >>Adenovirus-mediated CD40 Ligand Immunotherapy of Prostate and Bladder Cancer
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Cancer immunotherapy aims at reversing the immunosuppressive tumor environment and enhancing anti-tumor immunity. This thesis comprises studies on murine models for prostate (TRAMP-C2) and bladder (MB49) cancer with the aim to explore if the introduction of an adenoviral vector expressing CD40 ligand (AdCD40L) can induce anti-tumor immune responses.

We show in subcutaneous mouse models that AdCD40L treatment suppresses tumor growth. Bladder cancer is known to secrete immunosuppressive IL-10 which may inhibit T cell function. We show that introducing AdCD40L into mouse bladder tumors inhibits IL-10 production and reverses immunosuppression. AdCD40L-transduced mouse prostate cancer cells showed caspase activation and reduced cell viability. Vaccination with CD40L-modified prostate cancer cells induces anti-tumor responses and protects mice against rechallenge with native TRAMP-C2 cells. In order to enhance AdCD40L therapy, we explored the possibility of combining it with the histone deacetylase inhibitor FK228, also known as depsipeptide. We show that FK228 upregulates coxsackie and adenovirus receptor expression and thereby enhances adenoviral-mediated CD40L expression in both murine and human prostate cancer cells. Increasing amounts of FK228 or AdCD40L reduces prostate cancer cell viability, while the combined treatment gives at least an additive therapeutic effect. Moreover, we show that AdCD40L transduction of prostate cancer cells induces endogenous CD40 expression and sensitize them for CD40L-mediated therapy.

In order to conduct prostate-specific gene therapy, prostate-specific promoters can be used to drive transgene expression. However, there are no reports on prostate-specific promoters that are transcriptionally active in mouse cells. Here we show that by using the two-step transcription activation system (TSTA), we can enhance the activity of a recombinant human promoter sequence and obtain activity in mouse prostate cancer cells as well. This finding paves the way for future studies of prostate-specific gene therapy in immunocompetent mouse models.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 53 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 248
Medicine, immunotherapy, gene therapy, prostate cancer, bladder cancer, adenoviral vector, CD40 ligand, promoter, PPT, TSTA, depsipeptide FK228, TRAMP-C2, Medicin
urn:nbn:se:uu:diva-7810 (URN)978-91-554-6851-4 (ISBN)
Public defence
2007-05-04, Rudbecksalen, Rudbecklaboratoriet, Dag Hammarskjölds väg 20, Uppsala, 09:15
Available from: 2007-04-12 Created: 2007-04-12Bibliographically approved

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