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Regulated expression of diphtheria toxin in prostate cancer cells
Weidan Peng1, Amy Verbitsky, Yunhua Bao
1Lankenau Institute for Medical Research, Wynnewood, Pennsylvania 19096, USA. sawickij@mlhs.org
Abstract:
Despite their known potential for effectively killing cells, the therapeutic use of plant and bacterial toxins for the treatment of cancer has been slow to enter the clinical setting. This has been due in large part to the lack of gene regulatory elements that control expression of highly toxic genes in a sufficiently tight manner, such that the toxins are only expressed in specific target cells. "Leaky" promoters result in unwanted and harmful cell death. In this study, we tested a novel gene therapy strategy aimed at expressing diphtheria toxin (DT-A) in androgen-independent prostate cancer cells that express the protein BCL2. This strategy relies on both transcriptional regulation and inducibly regulated DNA recombination mediated by the site-directed Flp recombinase to control expression of the toxin. Adenoviruses are used to introduce the genetic elements required for this approach into cultured cells and xenografts. Administration of 4-hydroxytamoxifen, resulting in recombination and expression of the toxin, effectively kills the cancer cells. Our results suggest that following androgen ablation therapy for the treatment of prostate cancer, use of a regulated recombination system to target expression of DT-A to androgen-independent cancer cells would be an effective way to arrest the development of recurrent tumors.
Insights
This study introduces a novel gene therapy using diphtheria toxin (DT-A) to target prostate cancer cells. A regulated system effectively kills cancer cells, offering a new approach for recurrent tumor treatment.
Area of Science:
- Oncology
- Gene Therapy
- Molecular Biology
Background:
- Therapeutic use of potent toxins for cancer treatment is limited by the lack of precise gene expression control.
- "Leaky" promoters cause unintended cell death, hindering clinical application of toxic gene therapies.
- Androgen-independent prostate cancer cells pose a significant challenge after initial therapy.
Purpose of the Study:
- To develop and test a novel gene therapy strategy for targeting androgen-independent prostate cancer cells.
- To utilize a dual control system involving transcriptional regulation and inducible DNA recombination to control toxin expression.
- To investigate the efficacy of diphtheria toxin (DT-A) expression in BCL2-expressing prostate cancer cells.
Main Methods:
- Adenoviral vectors were used to deliver genetic elements for diphtheria toxin (DT-A) expression.
- A gene therapy strategy combining transcriptional regulation and Flp recombinase-mediated DNA recombination was employed.
- The system was tested in cultured cells and xenografts, with 4-hydroxytamoxifen used to induce recombination and toxin expression.
Main Results:
- The novel gene therapy strategy effectively killed androgen-independent prostate cancer cells expressing BCL2.
- Inducible DNA recombination mediated by Flp recombinase successfully controlled the expression of diphtheria toxin (DT-A).
- Administration of 4-hydroxytamoxifen triggered recombination and subsequent cancer cell death in vitro and in vivo.
Conclusions:
- This regulated recombination system offers a precise method for targeting diphtheria toxin (DT-A) expression to specific cancer cells.
- The approach holds promise for arresting the development of recurrent prostate cancer tumors following androgen ablation therapy.
- This gene therapy strategy represents a potential advancement in treating advanced prostate cancer by selectively eliminating resistant cells.