title: Phosphatidylinositol Induces Caspase-Independent Apoptosis of Malignant Pleural Mesothelioma Cells by Accumulating AIF in the Nucleus.
abstract: OBJECTIVE
  Phosphatidylinositol (PI) regulates a variety of cell processes. The present study investigated the antitumor action of 1,2-dioleoyl-sn-glycero-3-phospho-(1'-myo-inositol)(DOPI) and 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-myo-inositol)(DPPI) on human malignant pleural mesothelioma (MPM) cell lines such as NCI-H28, NCI-H2052, NCI-H2452, and MSTO-211H cells.
  
  
  METHODS
  MTT assay, TUNEL staining, flow cytometry using propidium iodide (PI) and annexin V (AV), enzymatic caspase assay, and nuclear staining using DAPI were carried out, and mitochondrial membrane potentials and intracellular distribution of apoptosis-inducing factor (AIF) were monitored in cells with and without the siRNA silencing the Bid-targeted gene.
  
  
  RESULTS
  Both DOPI and DPPI reduced cell viability for all the investigated MPM cell lines in a concentration (0.01-100 µM)-dependent manner. DOPI and DPPI significantly increased TUNEL-positive cells and the population of PI-negative/AV-positive and PI-positive/AV-positive cells, corresponding to early apoptosis and late apoptosis/secondary necrosis, respectively. DOPI and DPPI perturbed mitochondrial membrane potentials in MSTO-211H cells, but no significant activation of caspase-3, -4, -8, and -9 was obtained. DOPI and DPPI upregulated expression of Bid in MSTO-211H cells. DOPI and DPPI significantly increased nuclear localization of AIF without affecting expression of the mRNAs and proteins in MSTO-211H cells, which was inhibited by knocking-down Bid. In the DAPI staining, nuclear fragmentation and condensation were found.
  
  
  CONCLUSIONS
  The results of the present study indicate that DOPI and DPPI facilitate Bid-mediated AIF release from the mitochondria, to accumulate AIF in the nucleus and induce caspase-independent apoptosis of MPM cells.
authors.affiliation: Division of Respiratory Medicine, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Kanemura
authors.forename: Ayako
authors.initials: A
authors.lastname: Tsuchiya
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kanno
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakano
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Nishizaki
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051033:Apoptosis Inducing Factor / Q000235:genetics* / Q000378:metabolism; D051023:BH3 Interacting Domain Death Agonist Protein / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D020169:Caspases / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects* / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020287:In Situ Nick-End Labeling; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010716:Phosphatidylinositols; D010994:Pleura / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D021381:Protein Transport / Q000187:drug effects; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: C494829:AIFM1 protein, human; D051033:Apoptosis Inducing Factor; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D010716:Phosphatidylinositols; D034741:RNA, Small Interfering; D020169:Caspases