title: Cisplatin-induced apoptosis involves membrane fluidification via inhibition of NHE1 in human colon cancer cells.
abstract: We have previously shown that cisplatin triggers an early acid sphingomyelinase (aSMase)-dependent ceramide generation concomitantly with an increase in membrane fluidity and induces apoptosis in HT29 cells. The present study further explores the role and origin of membrane fluidification in cisplatin-induced apoptosis. The rapid increase in membrane fluidity following cisplatin treatment was inhibited by membrane-stabilizing agents such as cholesterol or monosialoganglioside-1. In HT29 cells, these compounds prevented the early aggregation of Fas death receptor and of membrane lipid rafts on cell surface and significantly inhibited cisplatin-induced apoptosis without altering drug intracellular uptake or cisplatin DNA adducts formation. Early after cisplatin treatment, Na+/H+ membrane exchanger-1 (NHE1) was inhibited leading to intracellular acidification, aSMase was activated, and ceramide was detected at the cell membrane. Treatment of HT29 cells with Staphylococcus aureus sphingomyelinase increased membrane fluidity. Moreover, pretreatment with cariporide, a specific inhibitor of NHE1, inhibited cisplatin-induced intracellular acidification, aSMase activation, ceramide membrane generation, membrane fluidification, and apoptosis. Finally, NHE1-expressing PS120 cells were more sensitive to cisplatin than NHE1-deficient PS120 cells. Altogether, these findings suggest that the apoptotic pathway triggered by cisplatin involves a very early NHE1-dependent intracellular acidification leading to aSMase activation and increase in membrane fluidity. These events are independent of cisplatin-induced DNA adducts formation. The membrane exchanger NHE1 may be another potential target of cisplatin, increasing cell sensitivity to this compound.
authors: Institut National de la Sante et de la Recherche Medicale, Unité Mixte de Recherche 620, Institut Fédératif de Recherche 140 Génétique Fonctionnelle Agronomie et Santé, France.
authors: Amélie
authors: A
authors: Rebillard
authors: Xavier
authors: X
authors: Tekpli
authors: Olivier
authors: O
authors: Meurette
authors: Odile
authors: O
authors: Sergent
authors: Gwenaëlle
authors: G
authors: LeMoigne-Muller
authors: Laurent
authors: L
authors: Vernhet
authors: Morgane
authors: M
authors: Gorria
authors: Martine
authors: M
authors: Chevanne
authors: Markus
authors: M
authors: Christmann
authors: Bernd
authors: B
authors: Kaina
authors: Laurent
authors: L
authors: Counillon
authors: Erich
authors: E
authors: Gulbins
authors: Dominique
authors: D
authors: Lagadic-Gossmann
authors: Marie-Thérèse
authors: MT
authors: Dimanche-Boitrel
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D027682:Cation Transport Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002784:Cholesterol / Q000494:pharmacology; D002945:Cisplatin / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D004347:Drug Interactions; D006146:Guanidines / Q000494:pharmacology; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D008560:Membrane Fluidity / Q000187:drug effects*; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013450:Sulfones / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D027682:Cation Transport Proteins; D006146:Guanidines; C490998:SLC9A1 protein, human; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers; D013450:Sulfones; C093373:cariporide; D002784:Cholesterol; D002945:Cisplatin