Identification of Cardiac Glycosides as Novel Inhibitors of eIF4A1-Mediated Translation in Triple-Negative Breast Cancer Cells
The eukaryotic translation initiation factor 4F complex (eIF4F) is a potential chemotherapeutic target in triple-negative breast cancer (TNBC). This complex regulates cap-dependent translational initiation and consists of three core proteins: eIF4E, eIF4G, and eIF4A1. In this study, we focus on repo...
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| Format: | Article |
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MDPI AG
2020-08-01
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| Series: | Cancers |
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| Online Access: | https://www.mdpi.com/2072-6694/12/8/2169 |
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| author | Cory M. Howard Matthew Estrada David Terrero Amit K. Tiwari Dayanidhi Raman |
| author_facet | Cory M. Howard Matthew Estrada David Terrero Amit K. Tiwari Dayanidhi Raman |
| author_sort | Cory M. Howard |
| collection | DOAJ |
| description | The eukaryotic translation initiation factor 4F complex (eIF4F) is a potential chemotherapeutic target in triple-negative breast cancer (TNBC). This complex regulates cap-dependent translational initiation and consists of three core proteins: eIF4E, eIF4G, and eIF4A1. In this study, we focus on repositioning compounds as novel inhibitors of eIF4A1-mediated translation. In order to accomplish this goal, a modified synthetic reporter assay was established. More specifically, a (CGG)<sub>4</sub> motif, which confers eIF4A dependency, was incorporated into the 5’-leader region of a luciferase-tdTomato lentiviral reporter construct. The Prestwick Chemical Library was then screened in multiple TNBC cell lines by measuring the tdTomato fluorescent intensity. We identified several cardiac glycosides as potential inhibitors of eIF4A1-mediated translation. Based on our studies, we find that cardiac glycosides inhibit the expression of eIF4A1. To identify a potential mechanism by which this was occurring, we utilized the Integrative Library of Integrated Network-Based Cellular Signatures (iLINCS). Our pursuits led us to the discovery that cardiac glycosides also decrease levels of c-MYC. Quantitative PCR confirmed that decreases in c-MYC and eIF4A were occurring at the transcriptional level. As such, disruption of the eIF4A1-c-MYC axis may be a viable approach in the treatment of TNBC. The novel combination of rocaglamide A and digoxin exhibited synergistic anti-cancer activity against TNBC cells in vitro. The findings in this study and others are important for formulating potential combination chemotherapies against eIF4A1 in vivo. Thus, drug repositioning may be one classical approach to successfully target eIF4A1 in TNBC patients. |
| first_indexed | 2024-03-10T17:58:22Z |
| format | Article |
| id | doaj.art-be799317a8584b0a80a09485accb654c |
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| issn | 2072-6694 |
| language | English |
| last_indexed | 2024-03-10T17:58:22Z |
| publishDate | 2020-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Cancers |
| spelling | doaj.art-be799317a8584b0a80a09485accb654c2023-11-20T09:04:17ZengMDPI AGCancers2072-66942020-08-01128216910.3390/cancers12082169Identification of Cardiac Glycosides as Novel Inhibitors of eIF4A1-Mediated Translation in Triple-Negative Breast Cancer CellsCory M. Howard0Matthew Estrada1David Terrero2Amit K. Tiwari3Dayanidhi Raman4Department of Cancer Biology, University of Toledo Health Science Campus, Toledo, OH 43614, USADepartment of Cancer Biology, University of Toledo Health Science Campus, Toledo, OH 43614, USADepartment of Pharmacology & Experimental Therapeutics, College of Pharmacy & Pharmaceutical Sciences, University of Toledo Main Campus, Toledo, OH 43606, USADepartment of Pharmacology & Experimental Therapeutics, College of Pharmacy & Pharmaceutical Sciences, University of Toledo Main Campus, Toledo, OH 43606, USADepartment of Cancer Biology, University of Toledo Health Science Campus, Toledo, OH 43614, USAThe eukaryotic translation initiation factor 4F complex (eIF4F) is a potential chemotherapeutic target in triple-negative breast cancer (TNBC). This complex regulates cap-dependent translational initiation and consists of three core proteins: eIF4E, eIF4G, and eIF4A1. In this study, we focus on repositioning compounds as novel inhibitors of eIF4A1-mediated translation. In order to accomplish this goal, a modified synthetic reporter assay was established. More specifically, a (CGG)<sub>4</sub> motif, which confers eIF4A dependency, was incorporated into the 5’-leader region of a luciferase-tdTomato lentiviral reporter construct. The Prestwick Chemical Library was then screened in multiple TNBC cell lines by measuring the tdTomato fluorescent intensity. We identified several cardiac glycosides as potential inhibitors of eIF4A1-mediated translation. Based on our studies, we find that cardiac glycosides inhibit the expression of eIF4A1. To identify a potential mechanism by which this was occurring, we utilized the Integrative Library of Integrated Network-Based Cellular Signatures (iLINCS). Our pursuits led us to the discovery that cardiac glycosides also decrease levels of c-MYC. Quantitative PCR confirmed that decreases in c-MYC and eIF4A were occurring at the transcriptional level. As such, disruption of the eIF4A1-c-MYC axis may be a viable approach in the treatment of TNBC. The novel combination of rocaglamide A and digoxin exhibited synergistic anti-cancer activity against TNBC cells in vitro. The findings in this study and others are important for formulating potential combination chemotherapies against eIF4A1 in vivo. Thus, drug repositioning may be one classical approach to successfully target eIF4A1 in TNBC patients.https://www.mdpi.com/2072-6694/12/8/2169eIF4A1c-MYCdigoxinbufalinrocaglamide ATNBC |
| spellingShingle | Cory M. Howard Matthew Estrada David Terrero Amit K. Tiwari Dayanidhi Raman Identification of Cardiac Glycosides as Novel Inhibitors of eIF4A1-Mediated Translation in Triple-Negative Breast Cancer Cells Cancers eIF4A1 c-MYC digoxin bufalin rocaglamide A TNBC |
| title | Identification of Cardiac Glycosides as Novel Inhibitors of eIF4A1-Mediated Translation in Triple-Negative Breast Cancer Cells |
| title_full | Identification of Cardiac Glycosides as Novel Inhibitors of eIF4A1-Mediated Translation in Triple-Negative Breast Cancer Cells |
| title_fullStr | Identification of Cardiac Glycosides as Novel Inhibitors of eIF4A1-Mediated Translation in Triple-Negative Breast Cancer Cells |
| title_full_unstemmed | Identification of Cardiac Glycosides as Novel Inhibitors of eIF4A1-Mediated Translation in Triple-Negative Breast Cancer Cells |
| title_short | Identification of Cardiac Glycosides as Novel Inhibitors of eIF4A1-Mediated Translation in Triple-Negative Breast Cancer Cells |
| title_sort | identification of cardiac glycosides as novel inhibitors of eif4a1 mediated translation in triple negative breast cancer cells |
| topic | eIF4A1 c-MYC digoxin bufalin rocaglamide A TNBC |
| url | https://www.mdpi.com/2072-6694/12/8/2169 |
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