title: The roles of antiapoptotic sphingosine kinase-1 and glucosylceramide genes in drug induced cell death of MCF-7 breast cancer cells.
abstract: OBJECTIVE
  Sphingolipids are important signaling molecules mediating cell survival, proliferation, cell cycle regulation and apoptosis. Ceramide is the most vital sphingolipid which induces growth arrest, senescence, and apoptosis. In this study, we aimed to determine the roles of sphingosine kinase-1 (SK-1) and glucosylceramide synthase (GCS) genes in paclitaxel, doxorubicin, tamoxifen, cyclophosphamide and docetaxel induced apoptosis in human MCF-7 breast cancer cells.
  
  
  METHODS
  IC50 values (drug concentration inhibiting cell growth by 50%) of the anticancer agents were calculated using XTT cell proliferation assay. Changes in mitochondrial membrane potential (MMP) were determined using JC-1 assay kit. Changes in the mRNA levels of SK-1 and GCS genes were measured by using RT-PCR technique.
  
  
  RESULTS
  The results demonstrated significant decrease in cellular proliferation and increase in loss of MMP in a dose-dependent manner. Paclitaxel, doxorubicin, tamoxifen, cyclophosphamide and docetaxel application downregulated SK-1 expression while paclitaxel, tamoxifen, cyclophosphamide and docetaxel but not doxorubicin downregulated GCS comparing to untreated control cells.
  
  
  CONCLUSIONS
  These results show for the first time that these agents induce apoptosis in MCF-7 cells by downregulating the antiapoptotic SK-1 and GCS genes that may result in accumulation of apoptotic ceramides.
authors.affiliation: Izmir Institute of Technology, Department of Molecular Biology and Genetics, Urla, Izmir, Turkey.
authors.forename: G
authors.initials: G
authors.lastname: Gucluler
authors.forename: O
authors.initials: O
authors.lastname: Piskin
authors.forename: Y
authors.initials: Y
authors.lastname: Baran
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D005963:Glucosylceramides / Q000235:genetics*; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D000099157:Sphingosine Kinase
chemical_list: D000970:Antineoplastic Agents; D005963:Glucosylceramides; D017853:Phosphotransferases (Alcohol Group Acceptor); D000099157:Sphingosine Kinase