title: Altered sphingolipid metabolism in N-(4-hydroxyphenyl)-retinamide-resistant A2780 human ovarian carcinoma cells.
abstract: In the present work, we studied the effects of fenretinide (N-(4-hydroxyphenyl)retinamide (HPR)), a hydroxyphenyl derivative of all-trans-retinoic acid, on sphingolipid metabolism and expression in human ovarian carcinoma A2780 cells. A2780 cells, which are sensitive to a pharmacologically achievable HPR concentration, become 10-fold more resistant after exposure to increasing HPR concentrations. Our results showed that HPR was able to induce a dose- and time-dependent increase in cellular ceramide levels in sensitive but not in resistant cells. This form of resistance in A2780 cells was not accompanied by the overexpression of multidrug resistance-specific proteins MDR1 P-glycoprotein and multidrug resistance-associated protein, whose mRNA levels did not differ in sensitive and resistant A2780 cells. HPR-resistant cells were characterized by an overall altered sphingolipid metabolism. The overall content in glycosphingolipids was similar in both cell types, but the expression of specific glycosphingolipids was different. Specifically, our findings indicated that glucosylceramide levels were similar in sensitive and resistant cells, but resistant cells were characterized by a 6-fold lower expression of lactosylceramide levels and by a 6-fold higher expression of ganglioside levels than sensitive cells. The main gangliosides from resistant A2780 cells were identified as GM3 and GM2. The possible metabolic mechanisms leading to this difference were investigated. Interestingly, the mRNA levels of glucosylceramide and lactosylceramide synthases were similar in sensitive and resistant cells, whereas GM3 synthase mRNA level and GM3 synthase activity were remarkably higher in resistant cells.
authors.affiliation: Center of Excellence on Neurodegenerative Diseases, Study Center for the Biochemistry and Biotechnology of Glycolipids, Department of Medical Chemistry, Biochemistry and Biotechnology, University of Milan, 20090 Segrate, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Prinetti
authors.forename: Luisa
authors.initials: L
authors.lastname: Basso
authors.forename: Valentina
authors.initials: V
authors.lastname: Appierto
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Villani
authors.forename: Manuela
authors.initials: M
authors.lastname: Valsecchi
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Loberto
authors.forename: Simona
authors.initials: S
authors.lastname: Prioni
authors.forename: Vanna
authors.initials: V
authors.lastname: Chigorno
authors.forename: Elena
authors.initials: E
authors.lastname: Cavadini
authors.forename: Franca
authors.initials: F
authors.lastname: Formelli
authors.forename: Sandro
authors.initials: S
authors.lastname: Sonnino
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001692:Biological Transport; D019008:Drug Resistance, Neoplasm; D005260:Female; D017313:Fenretinide / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007700:Kinetics; D010051:Ovarian Neoplasms; D013107:Sphingolipids / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents; C064769:N-acetylsphingosine; D013107:Sphingolipids; D017313:Fenretinide; D013110:Sphingosine