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Strategy for achieving selective killing of carcinomas
R I Garver1, K T Goldsmith, B Rodu
1Division of Pulmonary and Critical Care Medicine, UAB School of Medicine 35294, USA.
Abstract:
Carcinomas are malignancies derived from epithelial cells that frequently respond poorly to conventional chemotherapy. Selective expression or transduction of toxin genes to carcinomas, i.e. molecular chemotherapy, may offer important advantages over conventional chemotherapy. As one approach to developing a means of selectively expressing toxin genes, the transcriptional regulatory sequences of a gene expressed in multiple carcinomas were used to direct expression of the herpes simplex virus thymidine kinase (HSVtk) coding sequences. The secretory leukoprotease inhibitor (SLPI) gene was found to be expressed in lung, breast, oropharyngeal, bladder, endometrial, ovarian and colorectal carcinomas. The tissue-specific transcriptional regulatory sequences were isolated and used to construct a chimeric gene in which the SLPI sequences directed HSVtk expression. SLPI-expressing carcinomas were reduced in number by transduction of the SLPI-directed toxin plasmid plus ganciclovir, but the same treatment had no effect on a cell line that did not express SLPI. These results suggest that SLPI-directed therapeutic genes could be used for directing toxicity to carcinoma tissues, especially if combined with other targeting strategies.
Insights
Molecular chemotherapy using the secretory leukoprotease inhibitor (SLPI) gene shows promise. This approach selectively targets carcinomas expressing SLPI, reducing tumor cells with a specific toxin gene therapy.
Area of Science:
- Oncology
- Molecular Biology
- Gene Therapy
Background:
- Carcinomas, cancers from epithelial cells, often resist conventional chemotherapy.
- Targeted gene expression (molecular chemotherapy) offers potential advantages.
- Developing methods for selective toxin gene expression in carcinomas is crucial.
Purpose of the Study:
- To investigate the use of transcriptional regulatory sequences from a carcinoma-expressed gene to direct toxin gene expression.
- To construct a chimeric gene utilizing SLPI regulatory sequences to drive HSVtk expression.
Main Methods:
- Identified the secretory leukoprotease inhibitor (SLPI) gene as expressed in multiple carcinomas (lung, breast, oropharyngeal, bladder, endometrial, ovarian, colorectal).
- Isolated tissue-specific SLPI transcriptional regulatory sequences.
- Constructed a chimeric gene directing HSVtk expression via SLPI sequences.
- Administered SLPI-directed toxin plasmid plus ganciclovir to SLPI-expressing and non-expressing cell lines.
Main Results:
- Transduction of the SLPI-directed toxin plasmid plus ganciclovir reduced the number of SLPI-expressing carcinomas.
- The same treatment had no effect on cell lines lacking SLPI expression.
- Demonstrated selective toxicity towards carcinomas expressing SLPI.
Conclusions:
- SLPI-directed therapeutic genes show potential for targeted toxicity in carcinoma tissues.
- This approach may be enhanced when combined with other cancer targeting strategies.
- Molecular chemotherapy using SLPI offers a promising avenue for treating specific carcinomas.