Cytotoxicity of Anthrax Lethal Toxin to Human Acute Myeloid Leukemia Cells Is Nonapoptotic and Dependent on Extracellular Signal-Regulated Kinase 1/2 Activity
In this study, we attempt to target the mitogen-activated protein kinase (MAPK) pathway in acute myeloid leukemia (AML) cells using a recombinant anthrax lethal toxin (LeTx). LeTx consists of protective antigen (PrAg) and lethal factor (LF). PrAg binds cells, is cleaved by furin, oligomerizes, binds...
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| Format: | Article |
| Language: | English |
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Elsevier
2013-02-01
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| Series: | Translational Oncology |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1936523313800393 |
| _version_ | 1818502458065813504 |
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| author | Elias Kassab Manal Darwish Zahra Timsah ShiHui Liu Stephen H. Leppla Arthur E. Frankel Ralph J. Abi-Habib |
| author_facet | Elias Kassab Manal Darwish Zahra Timsah ShiHui Liu Stephen H. Leppla Arthur E. Frankel Ralph J. Abi-Habib |
| author_sort | Elias Kassab |
| collection | DOAJ |
| description | In this study, we attempt to target the mitogen-activated protein kinase (MAPK) pathway in acute myeloid leukemia (AML) cells using a recombinant anthrax lethal toxin (LeTx). LeTx consists of protective antigen (PrAg) and lethal factor (LF). PrAg binds cells, is cleaved by furin, oligomerizes, binds three to four molecules of LF, and undergoes endocytosis, releasing LF into the cytosol. LF cleaves MAPK kinases, inhibiting the MAPK pathway. We tested potency of LeTx on a panel of 11 human AML cell lines. Seven cell lines showed cytotoxic responses to LeTx. Cytotoxicity of LeTx was mimicked by the specific mitogen-activated protein/extracellular signal-regulated kinase kinase 1/2 (MEK1/2) inhibitor U0126, indicating that LeTx-induced cell death is mediated through the MEK1/2-extracellular signal-regulated kinase (ERK1/2) branch of the MAPK pathway. The four LeTx-resistant cell lines were sensitive to the phosphatidylinositol 3-kinase inhibitor LY294002. Co-treatment of AML cells with both LeTx and LY294002 did not lead to increased sensitivity, showing a lack of additive/synergistic effects when both pathways are inhibited. Flow cytometry analysis of MAPK pathway activation revealed the presence of phospho-ERK1/2 only in LeTx-sensitive cells. Staining for Annexin V/propidium iodide and active caspases showed an increase in double-positive cells and the absence of caspase activation following treatment, indicating that LeTx-induced cell death is caspase-independent and nonapoptotic. We have shown that a majority of AML cell lines are sensitive to the LF-mediated inhibition of the MAPK pathway. Furthermore, we have demonstrated that LeTx-induced cytotoxicity in AML cells is nonapoptotic and dependent on phospho-ERK1/2 levels. |
| first_indexed | 2024-12-10T21:10:30Z |
| format | Article |
| id | doaj.art-dedcb1e311af452abb41149b646d6a01 |
| institution | Directory Open Access Journal |
| issn | 1936-5233 |
| language | English |
| last_indexed | 2024-12-10T21:10:30Z |
| publishDate | 2013-02-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Translational Oncology |
| spelling | doaj.art-dedcb1e311af452abb41149b646d6a012022-12-22T01:33:30ZengElsevierTranslational Oncology1936-52332013-02-01612532Cytotoxicity of Anthrax Lethal Toxin to Human Acute Myeloid Leukemia Cells Is Nonapoptotic and Dependent on Extracellular Signal-Regulated Kinase 1/2 ActivityElias Kassab0Manal Darwish1Zahra Timsah2ShiHui Liu3Stephen H. Leppla4Arthur E. Frankel5Ralph J. Abi-Habib6Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Beirut, LebanonDepartment of Natural Sciences, School of Arts and Sciences, Lebanese American University, Beirut, LebanonDepartment of Natural Sciences, School of Arts and Sciences, Lebanese American University, Beirut, LebanonMicrobial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MDMicrobial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MDCancer Research Institute, Scott & White Memorial Hospital, Temple, TXDepartment of Natural Sciences, School of Arts and Sciences, Lebanese American University, Beirut, Lebanon; Address all correspondence to: Ralph J. Abi-Habib, PhD, Lebanese American University School of Arts and Sciences, Beirut 1102 2801, Lebanon.In this study, we attempt to target the mitogen-activated protein kinase (MAPK) pathway in acute myeloid leukemia (AML) cells using a recombinant anthrax lethal toxin (LeTx). LeTx consists of protective antigen (PrAg) and lethal factor (LF). PrAg binds cells, is cleaved by furin, oligomerizes, binds three to four molecules of LF, and undergoes endocytosis, releasing LF into the cytosol. LF cleaves MAPK kinases, inhibiting the MAPK pathway. We tested potency of LeTx on a panel of 11 human AML cell lines. Seven cell lines showed cytotoxic responses to LeTx. Cytotoxicity of LeTx was mimicked by the specific mitogen-activated protein/extracellular signal-regulated kinase kinase 1/2 (MEK1/2) inhibitor U0126, indicating that LeTx-induced cell death is mediated through the MEK1/2-extracellular signal-regulated kinase (ERK1/2) branch of the MAPK pathway. The four LeTx-resistant cell lines were sensitive to the phosphatidylinositol 3-kinase inhibitor LY294002. Co-treatment of AML cells with both LeTx and LY294002 did not lead to increased sensitivity, showing a lack of additive/synergistic effects when both pathways are inhibited. Flow cytometry analysis of MAPK pathway activation revealed the presence of phospho-ERK1/2 only in LeTx-sensitive cells. Staining for Annexin V/propidium iodide and active caspases showed an increase in double-positive cells and the absence of caspase activation following treatment, indicating that LeTx-induced cell death is caspase-independent and nonapoptotic. We have shown that a majority of AML cell lines are sensitive to the LF-mediated inhibition of the MAPK pathway. Furthermore, we have demonstrated that LeTx-induced cytotoxicity in AML cells is nonapoptotic and dependent on phospho-ERK1/2 levels.http://www.sciencedirect.com/science/article/pii/S1936523313800393 |
| spellingShingle | Elias Kassab Manal Darwish Zahra Timsah ShiHui Liu Stephen H. Leppla Arthur E. Frankel Ralph J. Abi-Habib Cytotoxicity of Anthrax Lethal Toxin to Human Acute Myeloid Leukemia Cells Is Nonapoptotic and Dependent on Extracellular Signal-Regulated Kinase 1/2 Activity Translational Oncology |
| title | Cytotoxicity of Anthrax Lethal Toxin to Human Acute Myeloid Leukemia Cells Is Nonapoptotic and Dependent on Extracellular Signal-Regulated Kinase 1/2 Activity |
| title_full | Cytotoxicity of Anthrax Lethal Toxin to Human Acute Myeloid Leukemia Cells Is Nonapoptotic and Dependent on Extracellular Signal-Regulated Kinase 1/2 Activity |
| title_fullStr | Cytotoxicity of Anthrax Lethal Toxin to Human Acute Myeloid Leukemia Cells Is Nonapoptotic and Dependent on Extracellular Signal-Regulated Kinase 1/2 Activity |
| title_full_unstemmed | Cytotoxicity of Anthrax Lethal Toxin to Human Acute Myeloid Leukemia Cells Is Nonapoptotic and Dependent on Extracellular Signal-Regulated Kinase 1/2 Activity |
| title_short | Cytotoxicity of Anthrax Lethal Toxin to Human Acute Myeloid Leukemia Cells Is Nonapoptotic and Dependent on Extracellular Signal-Regulated Kinase 1/2 Activity |
| title_sort | cytotoxicity of anthrax lethal toxin to human acute myeloid leukemia cells is nonapoptotic and dependent on extracellular signal regulated kinase 1 2 activity |
| url | http://www.sciencedirect.com/science/article/pii/S1936523313800393 |
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