title: Resistance to the antiproliferative effect induced by a short-chain ceramide is associated with an increase of glucosylceramide synthase, P-glycoprotein, and multidrug-resistance gene-1 in cervical cancer cells.
abstract: OBJECTIVE
  Ceramide is glycosylated to glucosylceramide or lactosylceramide, and this glycosylation is a novel multidrug-resistance (MDR) mechanism. In this work, a short-chain ceramide (C6), lactosylceramide (LacCer), and an inhibitor of ceramide glycosylation (D-threo-1-phenyl-2-decanoylamino-3-1-propanol, PDMP) were evaluated on the proliferation of cervical cancer cells. The participation of glucosylceramide synthase (GCS), P-glycoprotein (P-gp), and multidrug-resistance gene-1 (MDR-1) in the resistance to the antiproliferative effect induced by C6 was also evaluated.
  
  
  METHODS
  Cell proliferation was determined by crystal violet staining. GCS and MDR-1 mRNA expression was evaluated by real-time RT-PCR assay. GCS and P-gp protein expressions, as well as Rhodamine 123 uptake, which is a functional test for P-gp efflux activity, were determined by flow cytometry.
  
  
  RESULTS
  C6 inhibited proliferation of CaLo and CasKi cells with an IC₅₀ of 2.5 μM; however, 50% proliferation of ViBo cells was inhibited with 10 μM. LacCer increased the proliferation of all cells. When cells were treated with PDMP plus C6, no additional effect on antiproliferation induced by C6 was observed in CaLo and CasKi cells; however, proliferation diminished in comparison with C6 alone in ViBo cells. C6 increased GCS and MDR-1 expression in all cells, as well as P-gp expression in CasKi cells.
  
  
  CONCLUSIONS
  Cells that have more capacity to glycosylate ceramide and express a higher level of GCS, MDR-1, and P-gp, are more resistant to the antiproliferative effect induced by C6.
authors.affiliation: Laboratorio de Medicina Regenerativa y Estudios en Cáncer, Escuela Superior de Medicina, Instituto Politécnico Nacional, México, México.
authors.forename: Gisela
authors.initials: G
authors.lastname: Gutiérrez-Iglesias
authors.forename: Yamilec
authors.initials: Y
authors.lastname: Hurtado
authors.forename: Icela
authors.initials: I
authors.lastname: Palma-Lara
authors.forename: Rebeca
authors.initials: R
authors.lastname: López-Marure
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D004354:Drug Screening Assays, Antitumor; D005260:Female; D019450:Genes, MDR / Q000502:physiology*; D005964:Glucosyltransferases / Q000378:metabolism*; D006031:Glycosylation / Q000187:drug effects; D006801:Humans; D007790:Lactosylceramides / Q000378:metabolism*; D009025:Morpholines / Q000037:antagonists & inhibitors / Q000378:metabolism; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D014407:Tumor Cells, Cultured; D002583:Uterine Cervical Neoplasms / Q000378:metabolism*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D005964:Glucosyltransferases; D007790:Lactosylceramides; D009025:Morpholines; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C033110:RV 538; C023246:ceramide glucosyltransferase