title: Squamocin modulates histone H3 phosphorylation levels and induces G1 phase arrest and apoptosis in cancer cells.
abstract: BACKGROUND
  Histone modifications in tumorigenesis are increasingly recognized as important epigenetic factors leading to cancer. Increased phosphorylation levels of histone H3 as a result of aurora B and pMSK1 overexpression were observed in various tumors. We selected aurora B and MSK1 as representatives for testing various compounds and drugs, and found that squamocin, a bis-tetrahydrofuran annonaceous acetogenin, exerted a potent effect on histone H3 phosphorylation.
  
  
  METHODS
  GBM8401, Huh-7, and SW620 cells were incubated with 15, 30, and 60 μM squamocin for 24 h. The expressions of mRNA and proteins were analyzed by qRT-PCR and Western blotting, respectively. The cell viability was determined by an MTT assay. Cell cycle distribution and apoptotic cells were analyzed by flow cytometry.
  
  
  RESULTS
  Our results showed that squamocin inhibited the proliferation of GBM8401, Huh-7, and SW620 cells, arrested the cell cycle at the G1 phase, and activated both intrinsic and extrinsic pathways to apoptosis. In addition, we demonstrated that squamocin had the ability to modulate the phosphorylation levels of H3S10 (H3S10p) and H3S28 (H3S28p) in association with the downregulation of aurora B and pMSK1 expressions.
  
  
  CONCLUSIONS
  This study is the first to show that squamocin affects epigenetic alterations by modulating histone H3 phosphorylation at S10 and S28, providing a novel view of the antitumor mechanism of squamocin.
authors.affiliation: Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Chien-Chih
authors.initials: CC
authors.lastname: Lee
authors.forename: Yi-Hsiung
authors.initials: YH
authors.lastname: Lin
authors.forename: Wen-Hsin
authors.initials: WH
authors.lastname: Chang
authors.forename: Pei-Chin
authors.initials: PC
authors.lastname: Lin
authors.forename: Yang-Chang
authors.initials: YC
authors.lastname: Wu
authors.forename: Jan-Gowth
authors.initials: JG
authors.lastname: Chang
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003603:Cytotoxins / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004353:Drug Evaluation, Preclinical; D005663:Furans / Q000494:pharmacology*; D016193:G1 Phase / Q000187:drug effects*; D006657:Histones / Q000378:metabolism*; D006801:Humans; D007783:Lactones / Q000494:pharmacology*; D008954:Models, Biological; D009369:Neoplasms / Q000378:metabolism / Q000473:pathology*; D010766:Phosphorylation / Q000187:drug effects; D006656:Protamine Kinase / Q000378:metabolism*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D003603:Cytotoxins; D005663:Furans; D006657:Histones; D007783:Lactones; C059660:squamocin; D006656:Protamine Kinase