title: Novel cell death pathways induced by N-(4-hydroxyphenyl)retinamide: therapeutic implications.
abstract: We previously reported that N-(4-hydroxyphenyl)retinamide (4HPR) inhibits retinoblastoma tumor growth in a murine model in vivo and kills Y79 retinoblastoma cells in vitro. In this work, we assayed different cell death-related parameters, including mitochondrial damage and caspase activation, in Y79 cells exposed to 4HPR. 4HPR induced cytochrome c release from mitochondria, caspase-3 activation, and oligonucleosomal DNA fragmentation. However, pharmacologic inactivation of caspases by the pan-caspase inhibitor BOC-D-fmk, or specific caspase-3 inhibition by Z-DEVD-fmk, was not sufficient to prevent cell death, as assessed by loss of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction, lactate dehydrogenase release, disruption of mitochondrial transmembrane potential (Deltapsi(m)), and ATP depletion. We found that 4HPR causes lysosomal membrane permeabilization and cytosolic relocation of cathepsin D. Pepstatin A partially rescued cell viability and reduced DNA fragmentation and cytosolic cytochrome c. The antioxidant N-acetylcysteine attenuated cathepsin D relocation into the cytosol, suggesting that lysosomal destabilization is dependent on elevation of reactive oxygen species and precedes mitochondrial dysfunction. Activation of AKT, which regulates energy level in the cell, by the retinal survival facto]r insulin-like growth factor I was impaired and insulin-like growth factor I was ineffective against ATP and Deltapsi(m) loss in the presence of 4HPR. Lysosomal destabilization, associated with mitochondrial dysfunction, was induced by 4HPR also in other cancer cell lines, including PC3 prostate adenocarcinoma and the vascular tumor Kaposi sarcoma KS-Imm cells. The novel finding of a lysosome-mediated cell death pathway activated by 4HPR could have implications at clinical level for the development of combination chemoprevention and therapy of cancer.
authors.affiliation: IRCCS MultiMedica, Polo Scientifico e Tecnologico, Settore Ricerca Oncologica, Via Fantoli 15/16, Milan, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Venè
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Arena
authors.forename: Alessandro
authors.initials: A
authors.lastname: Poggi
authors.forename: Cristina
authors.initials: C
authors.lastname: D'Arrigo
authors.forename: Michele
authors.initials: M
authors.lastname: Mormino
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Noonan
authors.forename: Adriana
authors.initials: A
authors.lastname: Albini
authors.forename: Francesca
authors.initials: F
authors.lastname: Tosetti
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000172:deficiency; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001593:Benzyl Compounds / Q000494:pharmacology; D061945:Caspase Inhibitors; D002402:Cathepsin D / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000648:ultrastructure; D004789:Enzyme Activation / Q000187:drug effects; D005434:Flow Cytometry; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D008247:Lysosomes / Q000187:drug effects / Q000648:ultrastructure; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000648:ultrastructure; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012175:Retinoblastoma / Q000473:pathology / Q000628:therapy* / Q000648:ultrastructure; D013997:Time Factors; D014212:Tretinoin / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D001593:Benzyl Compounds; C476029:Boc-D-FMK; D061945:Caspase Inhibitors; D006845:Hydrocarbons, Fluorinated; D017382:Reactive Oxygen Species; D014212:Tretinoin; D007334:Insulin-Like Growth Factor I; D000255:Adenosine Triphosphate; D045304:Cytochromes c; C054441:retinamide; D051057:Proto-Oncogene Proteins c-akt; D002402:Cathepsin D; D000111:Acetylcysteine