title: A role for ceramide in driving cancer cell resistance to doxorubicin.
abstract: Advanced cancers acquire resistance to chemotherapy, and this results in treatment failure. The cellular mechanisms of chemotherapy resistance are not well understood. Here, for the first time, we show that ceramide contributes to cellular resistance to doxorubicin through up-regulating the gene expression of glucosylceramide synthase (GCS). Ceramide, a cellular lipid messenger, modulates doxorubicin-induced cell death. GCS catalyzes ceramide glycosylation, converting ceramide to glucosylceramide; this process hastens ceramide clearance and limits ceramide-induced apoptosis. In the present study, we evaluated the role of the GCS gene in doxorubicin resistance using several paired wild-type and drug-resistant (doxorubicin-selected) cancer cell lines, including breast, ovary, cervical, and colon. GCS was overexpressed in all drug-resistant counterparts, and suppressing GCS overexpression using antisense oligonucleotide restored doxorubicin sensitivity. Characterizing the effect mechanism showed that doxorubicin exposure increased ceramide levels, enhanced GCS expression, and imparted cellular resistance. Exogenous C(6)-ceramide and sphingomyelinase treatments mimicked the influence of doxorubicin on GCS, activating the GCS promoter and up-regulating GCS gene expression. Fumonisin B(1), an inhibitor of ceramide synthesis, significantly suppressed doxorubicin-up-regulated GCS expression. Promoter truncation, point mutation, gel-shift, and protein-DNA ELISA analysis showed that transcription factor Sp1 was essential for ceramide-induced GCS up-regulation. These data indicate that ceramide-governed GCS gene expression drives cellular resistance to doxorubicin.
authors.affiliation: Department of Basic Pharmaceutical Sciences, University of Louisiana at Monroe, 700 University Ave., Monroe, LA 71209, USA. yliu@ulm.edu
authors.forename: Yong-Yu
authors.initials: YY
authors.lastname: Liu
authors.forename: Jing Yuan
authors.initials: JY
authors.lastname: Yu
authors.forename: Dongmei
authors.initials: D
authors.lastname: Yin
authors.forename: Gauri Anand
authors.initials: GA
authors.lastname: Patwardhan
authors.forename: Vineet
authors.initials: V
authors.lastname: Gupta
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Hirabayashi
authors.forename: Walter M
authors.initials: WM
authors.lastname: Holleran
authors.forename: Armando E
authors.initials: AE
authors.lastname: Giuliano
authors.forename: S Michal
authors.initials: SM
authors.lastname: Jazwinski
authors.forename: Valerie
authors.initials: V
authors.lastname: Gouaze-Andersson
authors.forename: David P
authors.initials: DP
authors.lastname: Consoli
authors.forename: Myles C
authors.initials: MC
authors.lastname: Cabot
mesh_terms: D000230:Adenocarcinoma; D001943:Breast Neoplasms; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002518:Ceramides / Q000502:physiology*; D004317:Doxorubicin / Q000633:toxicity*; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005964:Glucosyltransferases / Q000235:genetics*; D006801:Humans; D016376:Oligonucleotides, Antisense / Q000494:pharmacology
chemical_list: D002518:Ceramides; D016376:Oligonucleotides, Antisense; D004317:Doxorubicin; D005964:Glucosyltransferases; C023246:ceramide glucosyltransferase