title: Enhanced cell cycle perturbation and apoptosis mediate the synergistic effects of ST1926 and ATRA in neuroblastoma preclinical models.
abstract: Retinoic acid therapy is nowadays an important component of treatment for residual disease of stage IV neuroblastoma after multimodal therapy. Nevertheless, arising resistance and treatment toxicity could represent relevant limiting factors. In the present study, we show that retinoic acid enhances the cytostatic and apoptogenic properties of the novel adamantyl retinoid ST1926 in a panel of neuroblastoma cells with different p53 status and caspase 8 expression, resulting in synergistic effects as assessed by Combination Index and Isobologram analysis. Under conditions where the two drugs alone produced no toxic effects, their combination resulted in enhanced G2-M arrest and sub-G1 population as shown by BrdU pulse-chase and labeling experiments. PARP cleavage, caspase 3, 8 and 9 activation and modulation of DR4 and FAS were indicative of enhanced apoptosis triggered by the co-incubation of the two drugs whereas neither ST1926-mediated genotoxic damage nor ATRA-differentiating effects were affected by the combined treatment. Caspase-3 and 8-mediated apoptosis appeared to play an important role in the drugs synergism. In fact, the addition of a pan-caspase inhibitor ZVAD-FMK reverted this effect in SK-N-DZ cells, and synergism was confined to limited drugs doses in HTLA cells not expressing caspase-8. Although not modulated, p53 appeared to enhance cells responsiveness to retinoid/ATRA combination. In vivo studies in the most sensitive neuroblastoma model SK-N-DZ, confirmed enhanced activity of the drugs combination vs single treatments. The study provides important lines of evidence that such a drugs combination could represent a less toxic and more effective approach for maintenance treatment in children with neuroblastoma.
authors.affiliation: Laboratory of Pharmacology, Division of Pediatric Oncology, Catholic University of Rome, L.go A. Gemelli 8, 00168 Rome, Italy. labfarm2@rm.unicatt.it
authors.forename: Angela Maria
authors.initials: AM
authors.lastname: Di Francesco
authors.forename: Paolo
authors.initials: P
authors.lastname: Ubezio
authors.forename: Anna Rita
authors.initials: AR
authors.lastname: Torella
authors.forename: Daniela
authors.initials: D
authors.lastname: Meco
authors.forename: Filomena
authors.initials: F
authors.lastname: Pierri
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Barone
authors.forename: Gabriella
authors.initials: G
authors.lastname: Cusano
authors.forename: Claudio
authors.initials: C
authors.lastname: Pisano
authors.forename: Maurizio
authors.initials: M
authors.lastname: D'Incalci
authors.forename: Riccardo
authors.initials: R
authors.lastname: Riccardi
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001973:Bromodeoxyuridine / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D002934:Cinnamates / Q000494:pharmacology* / Q000627:therapeutic use; D004249:DNA Damage; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D005434:Flow Cytometry; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008297:Male; D051379:Mice; D008954:Models, Biological; D009447:Neuroblastoma / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D011419:Propidium / Q000378:metabolism; D053218:Receptors, Death Domain / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: C472791:3-(4'-hydroxy-3'-adamantylbiphenyl-4-yl)acrylic acid; D000590:Amino Acid Chloromethyl Ketones; D002934:Cinnamates; D053218:Receptors, Death Domain; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D011419:Propidium; D014212:Tretinoin; D048031:JNK Mitogen-Activated Protein Kinases; D053148:Caspase 3; D001973:Bromodeoxyuridine; D000218:Adamantane