title: Glucosylceramide: a marker for multiple-drug resistant cancers.
abstract: BACKGROUND
  Multiple-drug resistance (MDR) is a major reason for chemotherapy failure. Herein we describe glucosylceramide, a new marker for MDR.
  
  
  METHODS
  Cellular lipids were analyzed in three human MDR cancer cell lines and their drug-sensitive counterparts. Analysis of glucosylceramide was also performed in six melanoma specimens and one breast tumor specimen obtained from patients who had undergone chemotherapy. Glucosylceramide, analyzed by mass and by cellular utilization of radiolabeled precursor ([3Hpalmitic acid), was isolated by lipid extraction techniques and resolved from other components by thin-layer chromatography.
  
  
  RESULTS
  Glucosylceramide was present consistently in all MDR cell lines and was absent, or present only at very low levels, in the corresponding drug-sensitive cells. Examination of human tumor specimens documented presence of the marker in all patients who had failed chemotherapy, and absence of the marker in each of the patients with known clinical response to chemotherapy. The response to chemotherapy was followed for a median of 8 months in melanoma patients and for 22 months in the breast cancer patient.
  
  
  CONCLUSIONS
  These findings suggest that glucosylceramide may hold clinical significance for the early identification of drug-resistant tumors.
authors.affiliation: Division of Surgical Oncology, Saint John's Health Center, Santa Monica, CA 90404, USA.
authors.forename: A
authors.initials: A
authors.lastname: Lucci
authors.forename: W I
authors.initials: WI
authors.lastname: Cho
authors.forename: T Y
authors.initials: TY
authors.lastname: Han
authors.forename: A E
authors.initials: AE
authors.lastname: Giuliano
authors.forename: D L
authors.initials: DL
authors.lastname: Morton
authors.forename: M C
authors.initials: MC
authors.lastname: Cabot
mesh_terms: D000293:Adolescent; D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism; D018432:Drug Resistance, Multiple; D005260:Female; D005963:Glucosylceramides / Q000378:metabolism*; D006801:Humans; D008297:Male; D008545:Melanoma / Q000188:drug therapy / Q000378:metabolism; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D014408:Biomarkers, Tumor; D005963:Glucosylceramides