title: Homoharringtonine binds to and increases myosin-9 in myeloid leukaemia.
abstract: OBJECTIVE
  Homoharringtonine (HHT) is a natural alkaloid isolated from various Cephalotaxus species. HHT has been used to treat acute myeloid leukaemia (AML), chronic myeloid leukaemia (CML), chronic lymphocyte leukaemia and myelodysplastic syndromes. Although HHT inhibits protein synthesis and promotes apoptosis of leukaemia cells in preclinical studies, its molecular target proteins remain unknown. The aim of this study was to identify target proteins of HHT.
  
  
  METHODS
  We have synthesized a biotinylated affinity column and used it to identify targets of HHT and confirmed the results by MS and Western blots. We also examined the effects of HHT on the target protein and determined roles of the target protein in anti-leukaemia activities of HHT through Western blots, flow cytometry and retrovirus transfection.
  
  
  RESULTS
  Myosin-9, a member of the myosin super-family, was identified as a direct interactor of HHT. Furthermore, HHT up-regulated the expression level of myosin-9 in both AML and CML cell lines in a time-dependent manner. Thus, HHT-induced apoptosis of leukaemia cells begins in 6 h and continues to increase for 24 h. There is a positive correlation between up-regulated myosin-9 expression level and increased percentage of apoptotic cells mediated by HHT. Overexpression of myosin-9 could increase the sensitivity of the leukaemia cells to the cytotoxicity of HHT and arrest cells in S and G2/M phases.
  
  
  CONCLUSIONS
  Our results indicated that myosin-9 was the target protein of HHT and played an important role in the HHT-induced apoptosis of leukaemia cells.
authors.affiliation: Department of Haematology and Institute of Haematology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Center for Developmental Therapeutics, Seattle Children's Research Institute, Division of Gastroenterology, Department of Pediatrics, University of Washington, Seattle, WA, USA.
authors.forename: Shuijie
authors.initials: S
authors.lastname: Shen
authors.affiliation: Department of Haematology and Institute of Haematology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Zhijuan
authors.initials: Z
authors.lastname: Zhu
authors.affiliation: Department of Haematology and Institute of Haematology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Shasha
authors.initials: S
authors.lastname: Lu
authors.affiliation: Department of Haematology and Institute of Haematology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Xiufeng
authors.initials: X
authors.lastname: Yin
authors.affiliation: Center for Developmental Therapeutics, Seattle Children's Research Institute, Division of Gastroenterology, Department of Pediatrics, University of Washington, Seattle, WA, USA.|Key Laboratory of Structure-Based Drug Design and Discovery of Ministry of Education, Shenyang Pharmaceutical University, Shenyang, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Department of Haematology and Institute of Haematology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Jin
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002846:Chromatography, Affinity; D006248:Harringtonines / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D000077863:Homoharringtonine; D006801:Humans; D007951:Leukemia, Myeloid / Q000378:metabolism*; D020409:Molecular Motor Proteins / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D006248:Harringtonines; C103814:MYH9 protein, human; D020409:Molecular Motor Proteins; D000077863:Homoharringtonine; D018995:Myosin Heavy Chains