ABSTRACT
BACKGROUND: Adenoviruses allow efficient transduction of dividing and non-dividing cells and their safety for the treatment of cancer has been established in clinical trials. However, one disadvantage is their promiscuous tropism. In this regard, tissue-specific promoters (TSPs) could be useful for directing transgene expression to target tissues and for reducing adverse effects in non-target tissues. We hypothesize that selective adenovirus-mediated transgene expression could be achieved through the use of the secretory leukoprotease inhibitor (SLPI) promoter in the context of ovarian cancer. METHODS: Adenoviruses containing the SLPI promoter driving reporter and suicide gene expression were created and tested in ovarian cancer cell lines and primary tumor cells isolated from patients. To evaluate the in vivo activation of the SLPI promoter in comparison to a ubiquitous promoter, intraperitoneal delivery was performed in tumor-bearing mice, followed by analysis of survival or gene expression in normal organs and tumor. RESULTS: The SLPI promoter retained its fidelity in an adenoviral context and was activated in both cell lines and primary cancer cells. The SLPI promoter was induced to a high degree in ovarian cancer cells while showing significantly reduced activity in normal tissues. The therapeutic efficacy of SLPI promoter-controlled gene expression was similar to the ubiquitous promoter in vitro and in an orthotopic murine model of peritoneally disseminated ovarian cancer, with higher activity than controls. CONCLUSIONS: The SLPI promoter is a potentially useful TSP for ovarian cancer and facilitates further development of targeting strategies for improved gene therapy of ovarian carcinomas.
Subject(s)
Genetic Therapy/methods , Ovarian Neoplasms/therapy , Promoter Regions, Genetic/genetics , Proteins/genetics , Adenocarcinoma/pathology , Adenocarcinoma/therapy , Adenoviridae/genetics , Animals , Cyclooxygenase 2 , Disease Models, Animal , Female , Gene Expression , Genetic Vectors/genetics , Genetic Vectors/pharmacology , Humans , Isoenzymes/genetics , Liver/physiology , Membrane Proteins , Mice , Mice, SCID , Ovarian Neoplasms/pathology , Peritoneal Neoplasms/secondary , Peritoneal Neoplasms/therapy , Prostaglandin-Endoperoxide Synthases/genetics , Proteinase Inhibitory Proteins, Secretory , Proteins/metabolism , Secretory Leukocyte Peptidase Inhibitor , Thymidine Kinase/genetics , Tumor Cells, CulturedABSTRACT
The purpose of this review article is to present a logical rationale for the investigation of conditionally replicative adenoviral vectors for the treatment of ovarian carcinoma. A medline database search was performed to identify relevant articles in the English language for the years 1966 to present. The key words used included replicative adenovirus, conditionally replicative adenovirus, transcriptional targeting, replication selective adenovirus, and "ONYX." A total of 89 references were identified and reviewed. Each reference was reviewed for relevance to clinical translation of conditionally replicative adenoviral vector therapy for ovarian cancer. Data from current clinical trials would suggest that potential obstacles for effective replicative viral therapy of ovarian carcinoma include efficient tumor cell infection, restrictions of the cell surface coxsackie and adenovirus receptor, rapid clearance of vector in the ascites environment, tumor cells specificity, and limitations of current findings of clinical trials. The articles were, therefore, evaluated and included if they addressed these shortcomings. Current data would suggest that advanced generation conditionally replicative adenoviral vectors will soon be available for clinical trials in ovarian cancer. Ovarian cancer, because of expression of targetable receptors, transducible cells, and containment within the i.p. cavity, represents a solid tumor suited uniquely for investigation with advanced generation conditionally replicative adenoviral vectors.
Subject(s)
Adenoviridae/genetics , Genetic Therapy , Ovarian Neoplasms/therapy , Animals , Female , Genetic Vectors , Humans , Virus ReplicationABSTRACT
Gene delivery efficiency in clinical cancer gene therapy trials with recombinant adenoviruses (Ads) based on serotype 5 (Ad5) has been limited partly because of variable expression of the primary Ad5 receptor, the coxsackie and adenovirus receptor (CAR), on human primary cancer cells. As a means of circumventing CAR deficiency, Ad vectors have been retargeted by creating chimeric fibers possessing knob domains of alternate Ad serotypes. In this study, we have constructed an Ad5-based vector, Ad5/3luc1, with a chimeric fiber protein featuring a knob domain derived from Ad3. This virus is retargeted to the Ad3 receptor and, therefore, has different tissue tropism. A novel knob binding assay was used to measure expression of CAR and the Ad3 receptor. Further, to evaluate the correlation of receptor expression and infectivity by Ad, a panel of ovarian cancer cell lines and purified primary cancer cells were infected with Ad5luc1 and Ad5/3luc1 at 50, 200, and 1000 viral particles/cell. Our results confirm that Ad5/3luc1 is retargeted to the Ad3 receptor. Furthermore, the Ad3 receptor is present at higher levels than CAR on ovarian adenocarcinoma cells. Also, the amount of binding to primary receptor appears to be the major factor determining the efficiency of transgene expression. The Ad5/3 chimera displays enhanced infectivity for ovarian cancer cell lines and purified primary tumor cells, which could translate into increased efficacy in clinical trials.
