title: Cisplatin-induced apoptosis involves a Fas-ROCK-ezrin-dependent actin remodelling in human colon cancer cells.
abstract: In human colon cancer cells, cisplatin-induced apoptosis involves the Fas death receptor pathway independent of Fas ligand. The present study explores the role of ezrin and actin cytoskeleton in relation with Fas receptor in this cell death pathway. In response to cisplatin treatment, a rapid and transient actin reorganisation is observed at the cell membrane by fluorescence microscopy after Phalloidin-FITC staining. This event is dependent on the membrane fluidification studied by electron paramagnetic resonance and necessary for apoptosis induction. Moreover, early after the onset of cisplatin treatment, ezrin co-localised with Fas at the cell membrane was visualised by membrane microscopy and was redistributed with Fas, FADD and procaspase-8 into membrane lipid rafts as shown on Western blots. In fact, cisplatin exposure results in an early small GTPase RhoA activation demonstrated by RhoA-GTP pull down, Rho kinase (ROCK)-dependent ezrin phosphorylation and actin microfilaments remodelling. Pretreatment with latrunculin A, an inhibitor of actin polymerisation, or specific extinction of ezrin or ROCK by RNA interference prevents both cisplatin-induced actin reorganisation and apoptosis. Interestingly, specific extinction of Fas receptor by RNA interference abrogates cisplatin-induced ROCK-dependent ezrin phosphorylation, actin reorganisation and apoptosis suggesting that Fas is a key regulator of cisplatin-induced actin remodelling and is indispensable for apoptosis. Thus, these findings show for the first time that phosphorylation of ezrin by ROCK via Fas receptor is involved in the early steps of cisplatin-induced apoptosis.
authors.affiliation: EA 4427 SeRAIC, Faculty of Pharmacy, University of Rennes 1, IFR 140 GFAS, Rennes F-35043, France.
authors.forename: Amélie
authors.initials: A
authors.lastname: Rebillard
authors.forename: Sandrine
authors.initials: S
authors.lastname: Jouan-Lanhouet
authors.forename: Elodie
authors.initials: E
authors.lastname: Jouan
authors.forename: Patrick
authors.initials: P
authors.lastname: Legembre
authors.forename: Mathieu
authors.initials: M
authors.lastname: Pizon
authors.forename: Odile
authors.initials: O
authors.lastname: Sergent
authors.forename: David
authors.initials: D
authors.lastname: Gilot
authors.forename: Xavier
authors.initials: X
authors.lastname: Tekpli
authors.forename: Dominique
authors.initials: D
authors.lastname: Lagadic-Gossmann
authors.forename: Marie-Thérèse
authors.initials: MT
authors.lastname: Dimanche-Boitrel
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002945:Cisplatin / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D003598:Cytoskeletal Proteins / Q000187:drug effects* / Q000378:metabolism; D053222:Fas Ligand Protein / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured; D019014:fas Receptor / Q000187:drug effects* / Q000378:metabolism; D000099149:Ezrin
chemical_list: D000970:Antineoplastic Agents; D002945:Cisplatin; D003598:Cytoskeletal Proteins; D053222:Fas Ligand Protein; D017346:Protein Serine-Threonine Kinases; D019014:fas Receptor; D000099149:Ezrin; C074377:actin kinase