RRC ID 28726
Author Min J, Traynor D, Stegner AL, Zhang L, Hanigan MH, Alexander H, Alexander S.
Title Sphingosine kinase regulates the sensitivity of Dictyostelium discoideum cells to the anticancer drug cisplatin.
Journal Eukaryot Cell
Abstract The drug cisplatin is widely used to treat a number of tumor types. However, resistance to the drug, which remains poorly understood, limits its usefulness. Previous work using Dictyostelium discoideum as a model for studying drug resistance showed that mutants lacking sphingosine-1-phosphate (S-1-P) lyase, the enzyme that degrades S-1-P, had increased resistance to cisplatin, whereas mutants overexpressing the enzyme were more sensitive to the drug. S-1-P is synthesized from sphingosine and ATP by the enzyme sphingosine kinase. We have identified two sphingosine kinase genes in D. discoideum--sgkA and sgkB--that are homologous to those of other species. The biochemical properties of the SgkA and SgkB enzymes suggest that they are the equivalent of the human Sphk1 and Sphk2 enzymes, respectively. Disruption of the kinases by homologous recombination (both single and double mutants) or overexpression of the sgkA gene resulted in altered growth rates and altered response to cisplatin. The null mutants showed increased sensitivity to cisplatin, whereas mutants overexpressing the sphingosine kinase resulted in increased resistance compared to the parental cells. The results indicate that both the SgkA and the SgkB enzymes function in regulating cisplatin sensitivity. The increase in sensitivity of the sphingosine kinase-null mutants was reversed by the addition of S-1-P, and the increased resistance of the sphingosine kinase overexpressor mutant was reversed by the inhibitor N,N-dimethylsphingosine. Parallel changes in sensitivity of the null mutants are seen with the platinum-based drug carboplatin but not with doxorubicin, 5-fluorouracil, and etoposide. This pattern of specificity is similar to that observed with the S-1-P lyase mutants and should be useful in designing therapeutic schemes involving more than one drug. This study identifies the sphingosine kinases as new drug targets for modulating the sensitivity to platinum-based drugs.
Volume 4(1)
Pages 178-89
Published 2005-1-1
DOI 10.1128/EC.4.1.178-189.2005
PII 4/1/178
PMID 15643073
PMC PMC544159
MeSH Adenosine Triphosphate / chemistry Adenosine Triphosphate / metabolism Amino Acid Sequence Animals Antineoplastic Agents / pharmacology Blotting, Western Cisplatin / pharmacology* Dictyostelium / drug effects* Dose-Response Relationship, Drug Doxorubicin / pharmacology Drug Resistance Etoposide / pharmacology Fluorouracil / pharmacology Microscopy, Fluorescence Models, Genetic Molecular Sequence Data Mutation Phosphotransferases (Alcohol Group Acceptor) / metabolism Phosphotransferases (Alcohol Group Acceptor) / physiology* Recombination, Genetic Sensitivity and Specificity Sequence Homology, Amino Acid Sphingosine / analogs & derivatives* Sphingosine / pharmacology Time Factors
IF 2.992
Times Cited 26
Cellular slime molds G22487 S00408 S90279