{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T04:48:47Z","timestamp":1787028527369,"version":"build-2736575974"},"reference-count":44,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2024,1,4]],"date-time":"2024-01-04T00:00:00Z","timestamp":1704326400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Marshall Eliuk Fund"},{"name":"Rachel Mandel Lymphoma and Blood Cancers Research Fund"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>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+ cells are more chemoresistant than SORE6\u2212 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+ compared to SORE6\u2212 cells. Similar observations were made using a fluorescence signal-based autophagy assay. Furthermore, chloroquine (an autophagy inhibitor) sensitized SORE6+ but not SORE6\u2212 cells to Ara-C. To decipher the molecular mechanisms underlying the high autophagic flux in SORE6+ cells, we employed an autophagy oligonucleotide array comparing gene expression between SORE6+ and SORE6\u2212 cells before and after Ara-C treatment. ULK2 was the most differentially expressed gene between the two cell subsets. To demonstrate the role of ULK2 in conferring higher chemoresistance in SORE6+ cells, we treated the two cell subsets with a ULK1\/2 inhibitor, MRT68921. MRT68921 significantly sensitized SORE6+ but not SORE6\u2212 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.<\/jats:p>","DOI":"10.3390\/ijms25010646","type":"journal-article","created":{"date-parts":[[2024,1,4]],"date-time":"2024-01-04T05:23:30Z","timestamp":1704345810000},"page":"646","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["ULK2 Is a Key Pro-Autophagy Protein That Contributes to the High Chemoresistance and Disease Relapse in FLT3-Mutated Acute Myeloid Leukemia"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8901-561X","authenticated-orcid":false,"given":"Justine","family":"Lai","sequence":"first","affiliation":[{"name":"Department of Medicine, Division of Hematology, University of Alberta, Edmonton, AB T6G 2R3, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Claire","family":"Yang","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2R3, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4240-2166","authenticated-orcid":false,"given":"Chuquan","family":"Shang","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2R3, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Will","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2R3, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael P.","family":"Chu","sequence":"additional","affiliation":[{"name":"Department of Medicine, Division of Hematology, University of Alberta, Edmonton, AB T6G 2R3, Canada"},{"name":"Department of Medical Oncology, Cross Cancer Institute, Edmonton, AB T6G 1Z2, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joseph","family":"Brandwein","sequence":"additional","affiliation":[{"name":"Department of Medicine, Division of Hematology, University of Alberta, Edmonton, AB T6G 2R3, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6963-2407","authenticated-orcid":false,"given":"Raymond","family":"Lai","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2R3, Canada"},{"name":"Department of Medical Oncology, Cross Cancer Institute, Edmonton, AB T6G 1Z2, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-4000-6372","authenticated-orcid":false,"given":"Peng","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Medicine, Division of Hematology, University of Alberta, Edmonton, AB T6G 2R3, Canada"},{"name":"Department of Medical Oncology, Cross Cancer Institute, Edmonton, AB T6G 1Z2, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,1,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"158","DOI":"10.1038\/s41568-019-0230-9","article-title":"The leukaemia stem cell: Similarities, differences and clinical prospects in CML and AML","volume":"20","author":"Vetrie","year":"2020","journal-title":"Nat. Rev. Cancer"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1798","DOI":"10.3324\/haematol.2018.203869","article-title":"Sequential therapy for patients with primary refractory acute myeloid leukemia: A historical prospective analysis of the German and Israeli experience","volume":"104","author":"Ram","year":"2019","journal-title":"Haematologica"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1136","DOI":"10.1056\/NEJMra1406184","article-title":"Acute Myeloid Leukemia","volume":"373","author":"Dohner","year":"2015","journal-title":"N. Engl. J. Med."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"672","DOI":"10.1093\/jnci\/djn123","article-title":"Intrinsic resistance of tumorigenic breast cancer cells to chemotherapy","volume":"100","author":"Li","year":"2008","journal-title":"J. Natl. Cancer Inst."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1016\/j.stemcr.2014.11.002","article-title":"A flexible reporter system for direct observation and isolation of cancer stem cells","volume":"4","author":"Tang","year":"2015","journal-title":"Stem Cell Rep."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"4","DOI":"10.1038\/367645a0","article-title":"A cell initiating human acute myeloid leukaemia after transplantation into SCID mice","volume":"367","author":"Lapidot","year":"1994","journal-title":"Nature"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"5402","DOI":"10.1182\/bloodadvances.2020001802","article-title":"CD200 expression marks leukemia stem cells in human AML","volume":"4","author":"Ho","year":"2020","journal-title":"Blood Adv."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"518","DOI":"10.21037\/atm.2016.11.82","article-title":"Aldehyde dehydrogenases in cancer stem cells: Potential as therapeutic targets","volume":"4","author":"Clark","year":"2016","journal-title":"Ann. Transl. Med."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"861","DOI":"10.1016\/j.cell.2007.11.019","article-title":"Induction of pluripotent stem cells from adult human fibroblasts by defined factors","volume":"131","author":"Takahashi","year":"2007","journal-title":"Cell"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"P\u00e1dua, D., Barros, R., Amaral, A.L., Mesquita, P., Freire, A.F., Sousa, M., Maia, A.F., Caiado, I., Fernandes, H., and Pombinho, A. (2020). A SOX2 Reporter System Identifies Gastric Cancer Stem-Like Cells Sensitive to Monensin. Cancers, 12.","DOI":"10.3390\/cancers12020495"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Vaddi, P.K., Stamnes, M.A., Cao, H., and Chen, S. (2019). Elimination of SOX2\/OCT4-Associated Prostate Cancer Stem Cells Blocks Tumor Development and Enhances Therapeutic Response. Cancers, 11.","DOI":"10.3390\/cancers11091331"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"543","DOI":"10.3390\/cimb43020041","article-title":"Identification and Characterization of Cancer Stem-like Cells in ALK-Positive Anaplastic Large Cell Lymphoma Using the SORE6 Reporter","volume":"43","author":"Li","year":"2021","journal-title":"Curr. Issues Mol. Biol."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Lai, J., Shang, C., Chen, W., Izevbaye, I., Chu, M.P., Sandhu, I., Brandwein, J., Lai, R., and Wang, P. (2024). An In Vitro Model for Acute Myeloid Leukemia Relapse Using the SORE6 Reporter. Int. J. Mol. Sci., 25.","DOI":"10.3390\/ijms25010496"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"103281","DOI":"10.1016\/j.critrevonc.2021.103281","article-title":"Update on drug transporter proteins in acute myeloid leukemia: Pathological implication and clinical setting","volume":"160","author":"Vasconcelos","year":"2021","journal-title":"Crit. Rev. Oncol. Hematol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"329","DOI":"10.1016\/j.stem.2012.12.013","article-title":"BCL-2 inhibition targets oxidative phosphorylation and selectively eradicates quiescent human leukemia stem cells","volume":"12","author":"Lagadinou","year":"2013","journal-title":"Cell Stem Cell"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2781","DOI":"10.1158\/1078-0432.CCR-16-1903","article-title":"AMPK-ULK1-Mediated Autophagy Confers Resistance to BET Inhibitor JQ1 in Acute Myeloid Leukemia Stem Cells","volume":"23","author":"Jang","year":"2017","journal-title":"Clin. Cancer Res."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"421","DOI":"10.1247\/csf.27.421","article-title":"Autophagosome formation in mammalian cells","volume":"27","author":"Mizushima","year":"2002","journal-title":"Cell Struct. Funct."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"e2943","DOI":"10.1038\/cddis.2017.327","article-title":"Autophagy inhibition reduces chemoresistance and tumorigenic potential of human ovarian cancer stem cells","volume":"8","author":"Pagotto","year":"2017","journal-title":"Cell Death Dis."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"e2927","DOI":"10.1038\/cddis.2017.317","article-title":"Inhibition of autophagy as a treatment strategy for p53 wild-type acute myeloid leukemia","volume":"8","author":"Folkerts","year":"2017","journal-title":"Cell Death Dis."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"132","DOI":"10.1016\/j.ceb.2009.12.004","article-title":"The role of the Atg1\/ULK1 complex in autophagy regulation","volume":"22","author":"Mizushima","year":"2010","journal-title":"Curr. Opin. Cell Biol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"124","DOI":"10.4161\/auto.23323","article-title":"The ULK1 complex: Sensing nutrient signals for autophagy activation","volume":"9","author":"Wong","year":"2013","journal-title":"Autophagy"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Ho, C.J., and Gorski, S.M. (2019). Molecular Mechanisms Underlying Autophagy-Mediated Treatment Resistance in Cancer. Cancers, 11.","DOI":"10.3390\/cancers11111775"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"787","DOI":"10.1038\/onc.2017.376","article-title":"Oncogenic FLT3-ITD supports autophagy via ATF4 in acute myeloid leukemia","volume":"37","author":"Heydt","year":"2018","journal-title":"Oncogene"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1186\/s13046-020-01580-4","article-title":"ULK1 inhibition as a targeted therapeutic strategy for FLT3-ITD-mutated acute myeloid leukemia","volume":"39","author":"Hwang","year":"2020","journal-title":"J. Exp. Clin. Cancer Res."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"2621","DOI":"10.1038\/s41375-022-01719-6","article-title":"Autophagy inhibition impairs leukemia stem cell function in FLT3-ITD AML but has antagonistic interactions with tyrosine kinase inhibition","volume":"36","author":"Qiu","year":"2022","journal-title":"Leukemia"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Marzagalli, M., Fontana, F., Raimondi, M., and Limonta, P. (2021). Cancer Stem Cells-Key Players in Tumor Relapse. Cancers, 13.","DOI":"10.3390\/cancers13030376"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"179","DOI":"10.1186\/s12943-015-0449-3","article-title":"Blockade of autophagy reduces pancreatic cancer stem cell activity and potentiates the tumoricidal effect of gemcitabine","volume":"14","author":"Yang","year":"2015","journal-title":"Mol. Cancer"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Zhang, D., Zhao, Q., Sun, H., Yin, L., Wu, J., Xu, J., He, T., Yang, C., and Liang, C. (2016). Defective autophagy leads to the suppression of stem-like features of CD271(+) osteosarcoma cells. J. Biomed. Sci., 23.","DOI":"10.1186\/s12929-016-0297-5"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"433","DOI":"10.1038\/nature20598","article-title":"A 17-gene stemness score for rapid determination of risk in acute leukaemia","volume":"540","author":"Ng","year":"2016","journal-title":"Nature"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1671","DOI":"10.1182\/blood-2016-02-695312","article-title":"Evolution of acute myelogenous leukemia stem cell properties after treatment and progression","volume":"128","author":"Ho","year":"2016","journal-title":"Blood"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"104","DOI":"10.1038\/nature22993","article-title":"Tracing the origins of relapse in acute myeloid leukaemia to stem cells","volume":"547","author":"Shlush","year":"2017","journal-title":"Nature"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"33704","DOI":"10.18632\/oncotarget.16734","article-title":"Ulk1 over-expression in human gastric cancer is correlated with patients\u2019 T classification and cancer relapse","volume":"8","author":"Chen","year":"2017","journal-title":"Oncotarget"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"389","DOI":"10.1042\/BJ20120972","article-title":"Transcriptional up-regulation of ULK1 by ATF4 contributes to cancer cell survival","volume":"449","author":"Pike","year":"2013","journal-title":"Biochem. J."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"10940","DOI":"10.1038\/s41598-020-67780-2","article-title":"ULK1 and ULK2 are less redundant than previously thought: Computational analysis uncovers distinct regulation and functions of these autophagy induction proteins","volume":"10","author":"Demeter","year":"2020","journal-title":"Sci. Rep."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1186\/1478-811X-10-7","article-title":"The incredible ULKs","volume":"10","author":"Alers","year":"2012","journal-title":"Cell Commun. Signal."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"585","DOI":"10.1042\/EBC20170021","article-title":"The mammalian ULK1 complex and autophagy initiation","volume":"61","author":"Zachari","year":"2017","journal-title":"Essays Biochem."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"689","DOI":"10.4161\/auto.7.7.15450","article-title":"The requirement of uncoordinated 51-like kinase 1 (ULK1) and ULK2 in the regulation of autophagy","volume":"7","author":"Lee","year":"2011","journal-title":"Autophagy"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"11121","DOI":"10.1073\/pnas.1107969108","article-title":"Ammonia-induced autophagy is independent of ULK1\/ULK2 kinases","volume":"108","author":"Cheong","year":"2011","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1493","DOI":"10.1182\/blood-2008-02-137398","article-title":"Ulk1 plays a critical role in the autophagic clearance of mitochondria and ribosomes during reticulocyte maturation","volume":"112","author":"Kundu","year":"2008","journal-title":"Blood"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"45","DOI":"10.4161\/auto.26505","article-title":"Analysis of a lung defect in autophagy-deficient mouse strains","volume":"10","author":"Cheong","year":"2014","journal-title":"Autophagy"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"2103","DOI":"10.4161\/auto.26563","article-title":"Distinct functions of Ulk1 and Ulk2 in the regulation of lipid metabolism in adipocytes","volume":"9","author":"Ro","year":"2013","journal-title":"Autophagy"},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Petherick, K.J., Conway, O.J., Mpamhanga, C., Osborne, S.A., Kamal, A., Saxty, B., and Ganley, I.G. (2015). Pharmacological inhibition of ULK1 kinase blocks mammalian target of rapamycin (mTOR)-dependent autophagy. J. Biol. Chem., 290.","DOI":"10.1074\/jbc.A114.627778"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"712","DOI":"10.1038\/s41419-020-02885-0","article-title":"Dual targeting of NUAK1 and ULK1 using the multitargeted inhibitor MRT68921 exerts potent antitumor activities","volume":"11","author":"Chen","year":"2020","journal-title":"Cell Death Dis."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"e12912","DOI":"10.1097\/MD.0000000000012912","article-title":"The clinical value of using chloroquine or hydroxychloroquine as autophagy inhibitors in the treatment of cancers: A systematic review and meta-analysis","volume":"97","author":"Xu","year":"2018","journal-title":"Medicine"}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/25\/1\/646\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T13:39:35Z","timestamp":1760103575000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/25\/1\/646"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,1,4]]},"references-count":44,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2024,1]]}},"alternative-id":["ijms25010646"],"URL":"https:\/\/doi.org\/10.3390\/ijms25010646","relation":{},"ISSN":["1422-0067"],"issn-type":[{"value":"1422-0067","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,1,4]]}}}