The Effect of Small Molecule Pharmacological Agents on the Triterpenoid Saponin Induced Endolysosomal Escape of Saporin and a Saporin-Based Immunotoxin in Target Human Lymphoma Cells
Triterpenoid saponins augment the cytotoxicity of saporin based immunotoxins. It is postulated that this results from a saponin-mediated increase in the endolysosomal escape of the toxin to the cytosol, but this remains to be confirmed. To address this issue, we used a number of pharmacological inhi...
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MDPI AG
2021-03-01
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| Series: | Biomedicines |
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| Online Access: | https://www.mdpi.com/2227-9059/9/3/300 |
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| author | Harrison J. Wensley Wendy S. Smith Suzanne E. Holmes Sopsamorn U. Flavell David J. Flavell |
| author_facet | Harrison J. Wensley Wendy S. Smith Suzanne E. Holmes Sopsamorn U. Flavell David J. Flavell |
| author_sort | Harrison J. Wensley |
| collection | DOAJ |
| description | Triterpenoid saponins augment the cytotoxicity of saporin based immunotoxins. It is postulated that this results from a saponin-mediated increase in the endolysosomal escape of the toxin to the cytosol, but this remains to be confirmed. To address this issue, we used a number of pharmacological inhibitors of endocytic processes as probes to investigate the role played by saponin in the endolysosomal escape of fluorescently labeled saporin and a saporin based immunotoxin targeted against CD38 on human lymphoma and leukemia cell lines. Endolysosomal escape of the toxin was measured by flow cytometric pulse shape analysis. These results were compared to the effects of the various inhibitors on the saponin-mediated augmentation of toxin and immunotoxin cytotoxicity. Inhibitors of clathrin-mediated endocytosis, micropinocytosis, and endosomal acidification abrogated the saponin-induced increase in the endolysosomal escape of the toxin into the cytosol, suggesting that these processes may be involved in the internalization of saponin to the same endolysosomal vesicle as the toxin. Alternatively, these processes may play a direct role in the mechanism by which saponin promotes toxin escape from the endolysosomal compartment to the cytosol. Correlation with the effects of these inhibitors on the augmentation of cytotoxicity provides additional evidence that endolysosomal escape is involved in driving augmentation. |
| first_indexed | 2024-03-10T13:13:52Z |
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| issn | 2227-9059 |
| language | English |
| last_indexed | 2024-03-10T13:13:52Z |
| publishDate | 2021-03-01 |
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| series | Biomedicines |
| spelling | doaj.art-cfc870a754924067a6d2bd4d265023b02023-11-21T10:33:13ZengMDPI AGBiomedicines2227-90592021-03-019330010.3390/biomedicines9030300The Effect of Small Molecule Pharmacological Agents on the Triterpenoid Saponin Induced Endolysosomal Escape of Saporin and a Saporin-Based Immunotoxin in Target Human Lymphoma CellsHarrison J. Wensley0Wendy S. Smith1Suzanne E. Holmes2Sopsamorn U. Flavell3David J. Flavell4Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton SO16 6YD, UKThe Simon Flavell Leukaemia Research Laboratory, Southampton General Hospital, Southampton SO16 6YD, UKThe Simon Flavell Leukaemia Research Laboratory, Southampton General Hospital, Southampton SO16 6YD, UKThe Simon Flavell Leukaemia Research Laboratory, Southampton General Hospital, Southampton SO16 6YD, UKThe Simon Flavell Leukaemia Research Laboratory, Southampton General Hospital, Southampton SO16 6YD, UKTriterpenoid saponins augment the cytotoxicity of saporin based immunotoxins. It is postulated that this results from a saponin-mediated increase in the endolysosomal escape of the toxin to the cytosol, but this remains to be confirmed. To address this issue, we used a number of pharmacological inhibitors of endocytic processes as probes to investigate the role played by saponin in the endolysosomal escape of fluorescently labeled saporin and a saporin based immunotoxin targeted against CD38 on human lymphoma and leukemia cell lines. Endolysosomal escape of the toxin was measured by flow cytometric pulse shape analysis. These results were compared to the effects of the various inhibitors on the saponin-mediated augmentation of toxin and immunotoxin cytotoxicity. Inhibitors of clathrin-mediated endocytosis, micropinocytosis, and endosomal acidification abrogated the saponin-induced increase in the endolysosomal escape of the toxin into the cytosol, suggesting that these processes may be involved in the internalization of saponin to the same endolysosomal vesicle as the toxin. Alternatively, these processes may play a direct role in the mechanism by which saponin promotes toxin escape from the endolysosomal compartment to the cytosol. Correlation with the effects of these inhibitors on the augmentation of cytotoxicity provides additional evidence that endolysosomal escape is involved in driving augmentation.https://www.mdpi.com/2227-9059/9/3/300saporinimmunotoxinaugmentationsaponinendocytosis |
| spellingShingle | Harrison J. Wensley Wendy S. Smith Suzanne E. Holmes Sopsamorn U. Flavell David J. Flavell The Effect of Small Molecule Pharmacological Agents on the Triterpenoid Saponin Induced Endolysosomal Escape of Saporin and a Saporin-Based Immunotoxin in Target Human Lymphoma Cells Biomedicines saporin immunotoxin augmentation saponin endocytosis |
| title | The Effect of Small Molecule Pharmacological Agents on the Triterpenoid Saponin Induced Endolysosomal Escape of Saporin and a Saporin-Based Immunotoxin in Target Human Lymphoma Cells |
| title_full | The Effect of Small Molecule Pharmacological Agents on the Triterpenoid Saponin Induced Endolysosomal Escape of Saporin and a Saporin-Based Immunotoxin in Target Human Lymphoma Cells |
| title_fullStr | The Effect of Small Molecule Pharmacological Agents on the Triterpenoid Saponin Induced Endolysosomal Escape of Saporin and a Saporin-Based Immunotoxin in Target Human Lymphoma Cells |
| title_full_unstemmed | The Effect of Small Molecule Pharmacological Agents on the Triterpenoid Saponin Induced Endolysosomal Escape of Saporin and a Saporin-Based Immunotoxin in Target Human Lymphoma Cells |
| title_short | The Effect of Small Molecule Pharmacological Agents on the Triterpenoid Saponin Induced Endolysosomal Escape of Saporin and a Saporin-Based Immunotoxin in Target Human Lymphoma Cells |
| title_sort | effect of small molecule pharmacological agents on the triterpenoid saponin induced endolysosomal escape of saporin and a saporin based immunotoxin in target human lymphoma cells |
| topic | saporin immunotoxin augmentation saponin endocytosis |
| url | https://www.mdpi.com/2227-9059/9/3/300 |
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