title: Induction of cytosine arabinoside-resistant human myeloid leukemia cell death through autophagy regulation by hydroxychloroquine.
abstract: We investigated the effects of the autophagy inhibitor hydroxychloroquine (HCQ) on cell death of cytosine arabinoside (Ara-C)-resistant human acute myeloid leukemia (AML) cells. Ara-C-sensitive (U937, AML-2) and Ara-C-resistant (U937/AR, AML-2/AR) human AML cell lines were used to evaluate HCQ-regulated cytotoxicity, autophagy, and apoptosis as well as effects on cell death-related signaling pathways. We found that HCQ-induced dose- and time-dependent cell death in Ara-C-resistant cells compared to Ara-C-sensitive cell lines. The extent of cell death and features of HCQ-induced autophagic markers including increase in microtubule-associated protein light chain 3 (LC3) I conversion to LC3-II, beclin-1, ATG5, as well as green fluorescent protein-LC3 positive puncta and autophagosome were remarkably greater in U937/AR cells. Also, p62/SQSTM1 was increased in response to HCQ. p62/SQSTM1 protein interacts with both LC3-II and ubiquitin protein and is degraded in autophagosomes. Therefore, a reduction of p62/SQSTM1 indicates increased autophagic degradation, whereas an increase of p62/SQSTM1 by HCQ indicates inhibited autophagic degradation. Knock down of p62/SQSTM1 using siRNA were prevented the HCQ-induced LC3-II protein level as well as significantly reduced the HCQ-induced cell death in U937/AR cells. Also, apoptotic cell death and caspase activation in U937/AR cells were increased by HCQ, provided evidence that HCQ-induced autophagy blockade. Taken together, our data show that HCQ-induced apoptotic cell death in Ara-C-resistant AML cells through autophagy regulation.
authors.affiliation: Division of Hematology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Yundeok
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Medical Research Center, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Ju-In
authors.initials: JI
authors.lastname: Eom
authors.affiliation: Medical Research Center, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Hoi-Kyung
authors.initials: HK
authors.lastname: Jeung
authors.affiliation: Division of Hematology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Ji Eun
authors.initials: JE
authors.lastname: Jang
authors.affiliation: Division of Hematology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Jin Seok
authors.initials: JS
authors.lastname: Kim
authors.affiliation: Division of Hematology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: June-Won
authors.initials: JW
authors.lastname: Cheong
authors.affiliation: Division of Pulmonology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Young Sam
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Division of Hematology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea; Medical Research Center, Yonsei University College of Medicine, Seoul, Republic of Korea. Electronic address: minbrmmd@yuhs.ac.
authors.forename: Yoo Hong
authors.initials: YH
authors.lastname: Min
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology / Q000627:therapeutic use; D001343:Autophagy / Q000187:drug effects* / Q000502:physiology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D003561:Cytarabine / Q000494:pharmacology / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D006886:Hydroxychloroquine / Q000494:pharmacology* / Q000627:therapeutic use; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy / Q000473:pathology*; D020298:U937 Cells
chemical_list: D000964:Antimetabolites, Antineoplastic; D003561:Cytarabine; D006886:Hydroxychloroquine
keywords: Acute myeloid leukemia; Apoptosis; Autophagy; Chemoresistance; Hydroxychloroquine