The long-term goal of this project is to develop non-viral DNA- based therapeutics with enhanced duration of transgene expression to treat squamous cell tumors. A major limitation of current gene expression systems is that the levels of expression are low and short-term. The duration of expression is limited by both pro- inflammatory cytokines and the rapid decline in plasmid levels. We have developed a powerful cell-based selection system that allows the rapid isolation of promoters with characteristics desirable for gene therapy. An important advantage of this approach is that it selects for promoters that function effectively in a non-viral plasmid, where it will be used. We will improve the duration of expression by constructing novel promoters that are both resistant to the inhibitory effects of pro-inflammatory cytokines and capable of high levels of expression. Regulatory sequences derived from bovine papilloma virus will be incorporated into the gene expression system so that the plasmid is either maintained in the nucleus or episomally replicated. We will evaluate the expression and persistence of this gene medicine in tumor cells. A gene expression system that provides higher levels of expression with increased persistence will have a significant advantage over other available plasmid systems.
The proposed research will lead to the development of plasmids with a prolonged duration of expression of therapeutic genes for the treatment of squamous cell carcinoma. There is a significant market (over 500,000 cases of squamous cell carcinoma worldwide) for improving the duration and level of genes when expressed in tumors. Controlling the duration and level of expression of specific therapeutic genes in tumors will improve the safety , and cost of treating patients with cancer.
