The Role of Cholesterol on Triterpenoid Saponin-Induced Endolysosomal Escape of a Saporin-Based Immunotoxin
Cholesterol seems to play a central role in the augmentation of saporin-based immunotoxin (IT) cytotoxicity by triterpenoid saponins. Endolysosomal escape has been proposed as one mechanism for the saponin-mediated enhancement of targeted toxins. We investigated the effects of lipid depletion follow...
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MDPI AG
2020-11-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/21/22/8734 |
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| author | Wendy S. Smith David A. Johnston Harrison J. Wensley Suzanne E. Holmes Sopsamorn U. Flavell David J. Flavell |
| author_facet | Wendy S. Smith David A. Johnston Harrison J. Wensley Suzanne E. Holmes Sopsamorn U. Flavell David J. Flavell |
| author_sort | Wendy S. Smith |
| collection | DOAJ |
| description | Cholesterol seems to play a central role in the augmentation of saporin-based immunotoxin (IT) cytotoxicity by triterpenoid saponins. Endolysosomal escape has been proposed as one mechanism for the saponin-mediated enhancement of targeted toxins. We investigated the effects of lipid depletion followed by repletion on <i>Saponinum album</i> (SA)-induced endolysosomal escape of Alexa Fluor labelled saporin and the saporin-based immunotoxin OKT10-SAP, directed against CD38, in Daudi lymphoma cells. Lipid deprived cells showed reduced SA-induced endolysosomal escape at two concentrations of SA, as determined by a flow cytometric method. The repletion of membrane cholesterol by low density lipoprotein (LDL) restored SA-induced endolysosomal escape at a concentration of 5 µg/mL SA but not at 1 µg/mL SA. When LDL was used to restore the cholesterol levels in lipid deprived cells, the SA augmentation of OKT10-SAP cytotoxicity was partially restored at 1 µg/mL SA and fully restored at 5 µg/mL SA. These results suggest that different mechanisms of action might be involved for the two different concentrations of SA and that endosomal escape may not be the main mechanism for the augmentation of saporin IT cytotoxicity by SA at the sub-lytic concentration of 1 µg/mL SA. |
| first_indexed | 2024-03-10T14:44:26Z |
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| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-10T14:44:26Z |
| publishDate | 2020-11-01 |
| publisher | MDPI AG |
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| series | International Journal of Molecular Sciences |
| spelling | doaj.art-fb969cae59384a43b231a91df65dd8df2023-11-20T21:31:20ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672020-11-012122873410.3390/ijms21228734The Role of Cholesterol on Triterpenoid Saponin-Induced Endolysosomal Escape of a Saporin-Based ImmunotoxinWendy S. Smith0David A. Johnston1Harrison J. Wensley2Suzanne E. Holmes3Sopsamorn U. Flavell4David J. Flavell5The Simon Flavell Leukaemia Research Laboratory, Southampton General Hospital, Southampton SO16 6YD, UKBiomedical Imaging Unit, University of Southampton Faculty of Medicine, 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, UKCholesterol seems to play a central role in the augmentation of saporin-based immunotoxin (IT) cytotoxicity by triterpenoid saponins. Endolysosomal escape has been proposed as one mechanism for the saponin-mediated enhancement of targeted toxins. We investigated the effects of lipid depletion followed by repletion on <i>Saponinum album</i> (SA)-induced endolysosomal escape of Alexa Fluor labelled saporin and the saporin-based immunotoxin OKT10-SAP, directed against CD38, in Daudi lymphoma cells. Lipid deprived cells showed reduced SA-induced endolysosomal escape at two concentrations of SA, as determined by a flow cytometric method. The repletion of membrane cholesterol by low density lipoprotein (LDL) restored SA-induced endolysosomal escape at a concentration of 5 µg/mL SA but not at 1 µg/mL SA. When LDL was used to restore the cholesterol levels in lipid deprived cells, the SA augmentation of OKT10-SAP cytotoxicity was partially restored at 1 µg/mL SA and fully restored at 5 µg/mL SA. These results suggest that different mechanisms of action might be involved for the two different concentrations of SA and that endosomal escape may not be the main mechanism for the augmentation of saporin IT cytotoxicity by SA at the sub-lytic concentration of 1 µg/mL SA.https://www.mdpi.com/1422-0067/21/22/8734saponinendosomal escapecholesterolimmunotoxinaugmentationsaporin |
| spellingShingle | Wendy S. Smith David A. Johnston Harrison J. Wensley Suzanne E. Holmes Sopsamorn U. Flavell David J. Flavell The Role of Cholesterol on Triterpenoid Saponin-Induced Endolysosomal Escape of a Saporin-Based Immunotoxin International Journal of Molecular Sciences saponin endosomal escape cholesterol immunotoxin augmentation saporin |
| title | The Role of Cholesterol on Triterpenoid Saponin-Induced Endolysosomal Escape of a Saporin-Based Immunotoxin |
| title_full | The Role of Cholesterol on Triterpenoid Saponin-Induced Endolysosomal Escape of a Saporin-Based Immunotoxin |
| title_fullStr | The Role of Cholesterol on Triterpenoid Saponin-Induced Endolysosomal Escape of a Saporin-Based Immunotoxin |
| title_full_unstemmed | The Role of Cholesterol on Triterpenoid Saponin-Induced Endolysosomal Escape of a Saporin-Based Immunotoxin |
| title_short | The Role of Cholesterol on Triterpenoid Saponin-Induced Endolysosomal Escape of a Saporin-Based Immunotoxin |
| title_sort | role of cholesterol on triterpenoid saponin induced endolysosomal escape of a saporin based immunotoxin |
| topic | saponin endosomal escape cholesterol immunotoxin augmentation saporin |
| url | https://www.mdpi.com/1422-0067/21/22/8734 |
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