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Published on: July 20, 2014
High-level, beta-catenin/TCF-dependent transgene expression in secondary colorectal cancer tissue
K S Lipinski1, A H Djeha, T Ismail
1Cobra Therapeutics Ltd, Stephenson Building, Keele University Science Park, Keele, Staffordshire, ST5 5SP, UK.
Abstract:
There is an urgent need for improved therapies for inoperable metastatic colon cancer. Gene-directed enzyme prodrug therapy (GDEPT) using adenovirus vectors works well in preclinical models of this disease, but successful clinical application is hampered by an inability to construct vectors that express at high levels in infected tumor cells but not in infected normal cells. Constitutive activation of beta-catenin-dependent gene expression is almost certainly a key causative event in the genesis of colon and some other cancers. Here we have exploited this oncogenic defect to design a synthetic promoter, CTP1, that, in contrast to currently available tumor-selective promoters, is both highly active in cancer cells and highly cancer-cell-specific. CTP1 directs high-level beta-galactosidase expression in freshly isolated biopsies of secondary colon cancer, but is not detectably active in associated normal liver tissue. We also demonstrate that CTP1 can direct high-level, tumor-specific therapeutic gene expression in vivo. Intratumoral injection of an adenovirus vector encoding Escherichia coli nitroreductase driven by CTP1 efficiently sensitized SW480 xenografts to the prodrug CB1954, whereas systemic vector and prodrug administration produced no apparent signs of toxicity. CTP1 may form the basis for effective, targeted gene therapy of metastatic colon cancer and other tumors with deregulated beta-catenin/T cell factor.
Insights
Researchers developed a novel synthetic promoter, CTP1, for gene therapy of metastatic colon cancer. This promoter shows high activity in cancer cells and specificity, offering a promising new avenue for targeted cancer treatment.
Area of Science:
- Oncology
- Molecular Biology
- Gene Therapy
Background:
- Metastatic colon cancer lacks effective therapies.
- Current gene-directed enzyme prodrug therapy (GDEPT) faces challenges with tumor-specific vector expression.
- Constitutive activation of beta-catenin signaling drives colon cancer development.
Purpose of the Study:
- To design and validate a novel synthetic promoter, CTP1, for highly active and tumor-specific gene expression in colon cancer.
- To assess the efficacy of CTP1 in directing therapeutic gene expression in vivo for metastatic colon cancer treatment.
Main Methods:
- Designed a synthetic promoter, CTP1, exploiting beta-catenin pathway activation in cancer cells.
- Evaluated CTP1 activity using beta-galactosidase expression in colon cancer biopsies and normal liver tissue.
- Utilized an adenovirus vector encoding Escherichia coli nitroreductase driven by CTP1 for in vivo studies in SW480 xenografts.
Main Results:
- CTP1 demonstrated high-level, cancer-cell-specific expression in colon cancer biopsies.
- CTP1 showed no detectable activity in associated normal liver tissue.
- Adenovirus-mediated delivery of nitroreductase via CTP1 sensitized SW480 xenografts to CB1954 with no observed toxicity.
Conclusions:
- CTP1 is a highly active and tumor-specific synthetic promoter for colon cancer.
- CTP1-driven gene therapy shows potential for treating metastatic colon cancer.
- This approach may be applicable to other tumors with deregulated beta-catenin/T cell factor signaling.
