ULK2 Is a Key Pro-Autophagy Protein That Contributes to the High Chemoresistance and Disease Relapse in FLT3-Mutated Acute Myeloid Leukemia
We recently demonstrated that a small subset of cells in FLT3-mutated acute myeloid leukemia (AML) cell lines exhibit SORE6 reporter activity and cancer stem-like features including chemoresistance. To study why SORE6<sup>+</sup> cells are more chemoresistant than SORE6<sup>−</s...
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MDPI AG
2024-01-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/25/1/646 |
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| author | Justine Lai Claire Yang Chuquan Shang Will Chen Michael P. Chu Joseph Brandwein Raymond Lai Peng Wang |
| author_facet | Justine Lai Claire Yang Chuquan Shang Will Chen Michael P. Chu Joseph Brandwein Raymond Lai Peng Wang |
| author_sort | Justine Lai |
| collection | DOAJ |
| description | We recently demonstrated that a small subset of cells in FLT3-mutated acute myeloid leukemia (AML) cell lines exhibit SORE6 reporter activity and cancer stem-like features including chemoresistance. To study why SORE6<sup>+</sup> cells are more chemoresistant than SORE6<sup>−</sup> cells, we hypothesized that these cells carry higher autophagy, a mechanism linked to chemoresistance. We found that cytarabine (Ara-C) induced a substantially higher protein level of LC3B-II in SORE6<sup>+</sup> compared to SORE6<sup>−</sup> cells. Similar observations were made using a fluorescence signal-based autophagy assay. Furthermore, chloroquine (an autophagy inhibitor) sensitized SORE6<sup>+</sup> but not SORE6<sup>−</sup> cells to Ara-C. To decipher the molecular mechanisms underlying the high autophagic flux in SORE6<sup>+</sup> cells, we employed an autophagy oligonucleotide array comparing gene expression between SORE6<sup>+</sup> and SORE6<sup>−</sup> cells before and after Ara-C treatment. <i>ULK2</i> was the most differentially expressed gene between the two cell subsets. To demonstrate the role of ULK2 in conferring higher chemoresistance in SORE6<sup>+</sup> cells, we treated the two cell subsets with a ULK1/2 inhibitor, MRT68921. MRT68921 significantly sensitized SORE6<sup>+</sup> but not SORE6<sup>−</sup> cells to Ara-C. Using our in vitro model for AML relapse, we found that regenerated AML cells contained higher ULK2 expression compared to pretreated cells. Importantly, inhibition of ULK2 using MRT68921 prevented in vitro AML relapse. Lastly, using pretreatment and relapsed AML patient bone marrow samples, we found that ULK2 expression was higher in relapsed AML. To conclude, our results supported the importance of autophagy in the relapse of FLT3-mutated AML and highlighted ULK2 in this context. |
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| institution | Directory Open Access Journal |
| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-08T15:04:53Z |
| publishDate | 2024-01-01 |
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| spelling | doaj.art-e2dd707e492f4c60bd0722c3203b65722024-01-10T15:00:23ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672024-01-0125164610.3390/ijms25010646ULK2 Is a Key Pro-Autophagy Protein That Contributes to the High Chemoresistance and Disease Relapse in FLT3-Mutated Acute Myeloid LeukemiaJustine Lai0Claire Yang1Chuquan Shang2Will Chen3Michael P. Chu4Joseph Brandwein5Raymond Lai6Peng Wang7Department of Medicine, Division of Hematology, University of Alberta, Edmonton, AB T6G 2R3, CanadaDepartment of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2R3, CanadaDepartment of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2R3, CanadaDepartment of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2R3, CanadaDepartment of Medicine, Division of Hematology, University of Alberta, Edmonton, AB T6G 2R3, CanadaDepartment of Medicine, Division of Hematology, University of Alberta, Edmonton, AB T6G 2R3, CanadaDepartment of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2R3, CanadaDepartment of Medicine, Division of Hematology, University of Alberta, Edmonton, AB T6G 2R3, CanadaWe recently demonstrated that a small subset of cells in FLT3-mutated acute myeloid leukemia (AML) cell lines exhibit SORE6 reporter activity and cancer stem-like features including chemoresistance. To study why SORE6<sup>+</sup> cells are more chemoresistant than SORE6<sup>−</sup> cells, we hypothesized that these cells carry higher autophagy, a mechanism linked to chemoresistance. We found that cytarabine (Ara-C) induced a substantially higher protein level of LC3B-II in SORE6<sup>+</sup> compared to SORE6<sup>−</sup> cells. Similar observations were made using a fluorescence signal-based autophagy assay. Furthermore, chloroquine (an autophagy inhibitor) sensitized SORE6<sup>+</sup> but not SORE6<sup>−</sup> cells to Ara-C. To decipher the molecular mechanisms underlying the high autophagic flux in SORE6<sup>+</sup> cells, we employed an autophagy oligonucleotide array comparing gene expression between SORE6<sup>+</sup> and SORE6<sup>−</sup> cells before and after Ara-C treatment. <i>ULK2</i> was the most differentially expressed gene between the two cell subsets. To demonstrate the role of ULK2 in conferring higher chemoresistance in SORE6<sup>+</sup> cells, we treated the two cell subsets with a ULK1/2 inhibitor, MRT68921. MRT68921 significantly sensitized SORE6<sup>+</sup> but not SORE6<sup>−</sup> cells to Ara-C. Using our in vitro model for AML relapse, we found that regenerated AML cells contained higher ULK2 expression compared to pretreated cells. Importantly, inhibition of ULK2 using MRT68921 prevented in vitro AML relapse. Lastly, using pretreatment and relapsed AML patient bone marrow samples, we found that ULK2 expression was higher in relapsed AML. To conclude, our results supported the importance of autophagy in the relapse of FLT3-mutated AML and highlighted ULK2 in this context.https://www.mdpi.com/1422-0067/25/1/646acute myeloid leukemiacancer stemnessrelapseautophagy |
| spellingShingle | Justine Lai Claire Yang Chuquan Shang Will Chen Michael P. Chu Joseph Brandwein Raymond Lai Peng Wang ULK2 Is a Key Pro-Autophagy Protein That Contributes to the High Chemoresistance and Disease Relapse in FLT3-Mutated Acute Myeloid Leukemia International Journal of Molecular Sciences acute myeloid leukemia cancer stemness relapse autophagy |
| title | ULK2 Is a Key Pro-Autophagy Protein That Contributes to the High Chemoresistance and Disease Relapse in FLT3-Mutated Acute Myeloid Leukemia |
| title_full | ULK2 Is a Key Pro-Autophagy Protein That Contributes to the High Chemoresistance and Disease Relapse in FLT3-Mutated Acute Myeloid Leukemia |
| title_fullStr | ULK2 Is a Key Pro-Autophagy Protein That Contributes to the High Chemoresistance and Disease Relapse in FLT3-Mutated Acute Myeloid Leukemia |
| title_full_unstemmed | ULK2 Is a Key Pro-Autophagy Protein That Contributes to the High Chemoresistance and Disease Relapse in FLT3-Mutated Acute Myeloid Leukemia |
| title_short | ULK2 Is a Key Pro-Autophagy Protein That Contributes to the High Chemoresistance and Disease Relapse in FLT3-Mutated Acute Myeloid Leukemia |
| title_sort | ulk2 is a key pro autophagy protein that contributes to the high chemoresistance and disease relapse in flt3 mutated acute myeloid leukemia |
| topic | acute myeloid leukemia cancer stemness relapse autophagy |
| url | https://www.mdpi.com/1422-0067/25/1/646 |
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