MEK Inhibition Sensitizes Precursor B-Cell Acute Lymphoblastic Leukemia (B-ALL) Cells to Dexamethasone through Modulation of mTOR Activity and Stimulation of Autophagy.
Resistance to glucocorticosteroids (GCs) is a major adverse prognostic factor in B-ALL, but the molecular mechanisms leading to GC resistance are not completely understood. Herein, we sought to elucidate the molecular background of GC resistance in B-ALL and characterize the therapeutic potential of...
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Public Library of Science (PLoS)
2016-01-01
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| author | Anna Polak Przemysław Kiliszek Tomasz Sewastianik Maciej Szydłowski Ewa Jabłońska Emilia Białopiotrowicz Patryk Górniak Sergiusz Markowicz Eliza Nowak Monika A Grygorowicz Monika Prochorec-Sobieszek Dominika Nowis Jakub Gołąb Sebastian Giebel Ewa Lech-Marańda Krzysztof Warzocha Przemysław Juszczyński |
| author_facet | Anna Polak Przemysław Kiliszek Tomasz Sewastianik Maciej Szydłowski Ewa Jabłońska Emilia Białopiotrowicz Patryk Górniak Sergiusz Markowicz Eliza Nowak Monika A Grygorowicz Monika Prochorec-Sobieszek Dominika Nowis Jakub Gołąb Sebastian Giebel Ewa Lech-Marańda Krzysztof Warzocha Przemysław Juszczyński |
| author_sort | Anna Polak |
| collection | DOAJ |
| description | Resistance to glucocorticosteroids (GCs) is a major adverse prognostic factor in B-ALL, but the molecular mechanisms leading to GC resistance are not completely understood. Herein, we sought to elucidate the molecular background of GC resistance in B-ALL and characterize the therapeutic potential of targeted intervention in these mechanisms. Using exploratory bioinformatic approaches, we found that resistant cells exhibited significantly higher expression of MEK/ERK (MAPK) pathway components. We found that GC-resistant ALL cell lines had markedly higher baseline activity of MEK and small-molecule MEK1/2 inhibitor selumetinib increased GCs-induced cell death. MEK inhibitor similarly increased in vitro dexamethasone activity in primary ALL blasts from 19 of 22 tested patients. To further confirm these observations, we overexpressed a constitutively active MEK mutant in GC-sensitive cells and found that forced MEK activity induced resistance to dexamethasone. Since recent studies highlight the role GC-induced autophagy upstream of apoptotic cell death, we assessed LC3 processing, MDC staining and GFP-LC3 relocalization in cells incubated with either DEX, SEL or combination of drugs. Unlike either drug alone, only their combination markedly increased these markers of autophagy. These changes were associated with decreased mTOR activity and blocked 4E-BP1 phosphorylation. In cells with silenced beclin-1 (BCN1), required for autophagosome formation, the synergy of DEX and SEL was markedly reduced. Taken together, we show that MEK inhibitor selumetinib enhances dexamethasone toxicity in GC-resistant B-ALL cells. The underlying mechanism of this interaction involves inhibition of mTOR signaling pathway and modulation of autophagy markers, likely reflecting induction of this process and required for cell death. Thus, our data demonstrate that modulation of MEK/ERK pathway is an attractive therapeutic strategy overcoming GC resistance in B-ALL patients. |
| format | Article |
| id | doaj-art-ec99e861f49948bfbeab3b1d6710b2f9 |
| institution | OA Journals |
| issn | 1932-6203 |
| language | English |
| publishDate | 2016-01-01 |
| publisher | Public Library of Science (PLoS) |
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| spelling | doaj-art-ec99e861f49948bfbeab3b1d6710b2f92025-08-20T02:15:41ZengPublic Library of Science (PLoS)PLoS ONE1932-62032016-01-01115e015589310.1371/journal.pone.0155893MEK Inhibition Sensitizes Precursor B-Cell Acute Lymphoblastic Leukemia (B-ALL) Cells to Dexamethasone through Modulation of mTOR Activity and Stimulation of Autophagy.Anna PolakPrzemysław KiliszekTomasz SewastianikMaciej SzydłowskiEwa JabłońskaEmilia BiałopiotrowiczPatryk GórniakSergiusz MarkowiczEliza NowakMonika A GrygorowiczMonika Prochorec-SobieszekDominika NowisJakub GołąbSebastian GiebelEwa Lech-MarańdaKrzysztof WarzochaPrzemysław JuszczyńskiResistance to glucocorticosteroids (GCs) is a major adverse prognostic factor in B-ALL, but the molecular mechanisms leading to GC resistance are not completely understood. Herein, we sought to elucidate the molecular background of GC resistance in B-ALL and characterize the therapeutic potential of targeted intervention in these mechanisms. Using exploratory bioinformatic approaches, we found that resistant cells exhibited significantly higher expression of MEK/ERK (MAPK) pathway components. We found that GC-resistant ALL cell lines had markedly higher baseline activity of MEK and small-molecule MEK1/2 inhibitor selumetinib increased GCs-induced cell death. MEK inhibitor similarly increased in vitro dexamethasone activity in primary ALL blasts from 19 of 22 tested patients. To further confirm these observations, we overexpressed a constitutively active MEK mutant in GC-sensitive cells and found that forced MEK activity induced resistance to dexamethasone. Since recent studies highlight the role GC-induced autophagy upstream of apoptotic cell death, we assessed LC3 processing, MDC staining and GFP-LC3 relocalization in cells incubated with either DEX, SEL or combination of drugs. Unlike either drug alone, only their combination markedly increased these markers of autophagy. These changes were associated with decreased mTOR activity and blocked 4E-BP1 phosphorylation. In cells with silenced beclin-1 (BCN1), required for autophagosome formation, the synergy of DEX and SEL was markedly reduced. Taken together, we show that MEK inhibitor selumetinib enhances dexamethasone toxicity in GC-resistant B-ALL cells. The underlying mechanism of this interaction involves inhibition of mTOR signaling pathway and modulation of autophagy markers, likely reflecting induction of this process and required for cell death. Thus, our data demonstrate that modulation of MEK/ERK pathway is an attractive therapeutic strategy overcoming GC resistance in B-ALL patients.https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0155893&type=printable |
| spellingShingle | Anna Polak Przemysław Kiliszek Tomasz Sewastianik Maciej Szydłowski Ewa Jabłońska Emilia Białopiotrowicz Patryk Górniak Sergiusz Markowicz Eliza Nowak Monika A Grygorowicz Monika Prochorec-Sobieszek Dominika Nowis Jakub Gołąb Sebastian Giebel Ewa Lech-Marańda Krzysztof Warzocha Przemysław Juszczyński MEK Inhibition Sensitizes Precursor B-Cell Acute Lymphoblastic Leukemia (B-ALL) Cells to Dexamethasone through Modulation of mTOR Activity and Stimulation of Autophagy. PLoS ONE |
| title | MEK Inhibition Sensitizes Precursor B-Cell Acute Lymphoblastic Leukemia (B-ALL) Cells to Dexamethasone through Modulation of mTOR Activity and Stimulation of Autophagy. |
| title_full | MEK Inhibition Sensitizes Precursor B-Cell Acute Lymphoblastic Leukemia (B-ALL) Cells to Dexamethasone through Modulation of mTOR Activity and Stimulation of Autophagy. |
| title_fullStr | MEK Inhibition Sensitizes Precursor B-Cell Acute Lymphoblastic Leukemia (B-ALL) Cells to Dexamethasone through Modulation of mTOR Activity and Stimulation of Autophagy. |
| title_full_unstemmed | MEK Inhibition Sensitizes Precursor B-Cell Acute Lymphoblastic Leukemia (B-ALL) Cells to Dexamethasone through Modulation of mTOR Activity and Stimulation of Autophagy. |
| title_short | MEK Inhibition Sensitizes Precursor B-Cell Acute Lymphoblastic Leukemia (B-ALL) Cells to Dexamethasone through Modulation of mTOR Activity and Stimulation of Autophagy. |
| title_sort | mek inhibition sensitizes precursor b cell acute lymphoblastic leukemia b all cells to dexamethasone through modulation of mtor activity and stimulation of autophagy |
| url | https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0155893&type=printable |
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