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Measuring Peptide Translocation into Large Unilamellar Vesicles
Published on: January 27, 2012
Biological evaluation of penetration domain and killing domain peptides
Y P R Jarajapu1, J Baltunis, H J Knot
1Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL, USA.
Background:
Cancer gene therapy must impact the majority of cells to be effective. Current gene delivery systems are unable to achieve sufficient transfer efficiency to the tumor cells. Cell killing can be dramatically increased through a bystander effect. Modeling the gene product with synthetic peptides can identify key elements for creating cell killing through a bystander effect.
Methods:
Fluorescent labeled peptides were used for uptake kinetic studies and determination of intracellular localization in human glioblastoma cell lines, rat glioma cells lines and pressurized rat cerebral arteries. The degree of cell killing was assayed using propidium iodide coupled with fluorescence-activated cell sorting (FACS) analysis.
Results:
Peptides derived from HIV Tat and Drosophila antennapedia homeodomain were taken up by all tumor and primary cells. Attachment of an Mdm-2-binding domain derived from P14(ARF) resulted in cell killing and was independent of domain orientation. Uptake kinetics showed rapid uptake for both tumor and primary cells equilibrating with the external media within 10 min. Intraluminal or extraluminal administration of peptides into pressurized cerebral arteries showed a lack of extravasation across the subbasement lamina. Assay of biological activity following intraluminal administration showed selective suppression of response to vasodilation with no effect on response by smooth muscle cells.
Conclusions:
The results from these studies identified: (1) a cell trafficking domain and a cytotoxic domain for killing brain tumor cells; (2) that cell killing was independent of the domain orientations with regard to the cell trafficking domain being at the C-terminus or N-terminus; and (3) that the dual domain peptide can also be taken up by endothelial cells as shown by the cerebral artery studies. Hence, localized expression of the cytotoxic gene has the potential to not only kill brain tumor cells, but also tumor endothelium, thus further increasing the effectiveness of the therapy.
Insights
Synthetic peptides show promise for cancer gene therapy by effectively killing brain tumor cells and tumor endothelium. These peptides utilize a cell trafficking domain and a cytotoxic domain, offering a novel approach to enhance therapeutic efficacy.
Area of Science:
- Biochemistry
- Molecular Biology
- Cancer Research
Background:
- Effective cancer gene therapy requires high-efficiency delivery to a majority of tumor cells.
- Current gene delivery systems face challenges in achieving sufficient tumor cell transfer efficiency.
- The bystander effect can significantly enhance cell killing, offering a potential therapeutic strategy.
Purpose of the Study:
- To model gene products using synthetic peptides to identify key elements for bystander-mediated cell killing.
- To investigate the uptake kinetics and intracellular localization of fluorescently labeled peptides.
- To assess the cell-killing efficacy of engineered peptides in glioblastoma and glioma models.
Main Methods:
- Utilized fluorescently labeled peptides for uptake studies in human glioblastoma and rat glioma cell lines.
- Employed propidium iodide staining and fluorescence-activated cell sorting (FACS) to quantify cell death.
- Investigated peptide behavior in pressurized rat cerebral arteries to assess extravasation and endothelial cell interaction.
Main Results:
- Peptides derived from HIV Tat and Drosophila antennapedia homeodomain demonstrated uptake in both tumor and primary cells.
- Attachment of an Mdm-2-binding domain from P14(ARF) induced cell killing, irrespective of domain orientation.
- Peptides were rapidly internalized by cells within 10 minutes and showed limited extravasation in cerebral arteries, selectively affecting vasodilation response.
Conclusions:
- Identified distinct cell trafficking and cytotoxic domains for effective brain tumor cell killing.
- Demonstrated that cell killing is independent of domain orientation (N-terminus vs. C-terminus).
- Showed dual-domain peptide uptake by endothelial cells, suggesting potential for targeting both tumor cells and tumor vasculature for enhanced therapy.
