A sphingosine kinase inhibitor induces cell death in temozolomide resistant glioblastoma cells.
OBJECTIVE
Sphingosine kinase is an oncogene that is up-regulated in several solid tumors. The product of the sphingosine kinase activity, sphingosine-1-phosphate is a potent mitogen involved in diverse cell processes such as cell survival and migration. Current standard therapy in the treatment of glioblastoma multiforme (GBM) is a combination of surgery, radiation, and chemotherapy using the drug temozolomide (TMZ). However, virtually all tumors become resistant to TMZ. Therefore, new drug targets are necessary. In this study, we investigated whether inhibiting sphingosine kinase could induce cell death in TMZ-resistant GBM cells.


METHODS
To study TMZ resistance in vitro, we have generated TMZ-resistant cell lines from established GBM cells. We used a potent inhibitor of sphingosine kinase to study its effect on colony formation and cell growth in GBM cells with a limited dilution and WST assay. Moreover, cell death was determined by measuring caspase-3 activity using flow cytometry.


RESULTS
A sphingosine kinase inhibitor reduced cell colony formation and activated caspase-3 in both TMZ-sensitive and resistant GBM cells.


CONCLUSIONS
Addition of a sphingosine kinase inhibitor to the standard chemotherapy regimen against GBM may be beneficial.
Bektas
Meryem
M
Department of Pathology, Duke University Medical Center, Durham, NC, USA. meryem_bektas@med.unc.edu
Johnson
Stewart P
SP
Poe
William E
WE
Bigner
Darell D
DD
Friedman
Henry S
HS
D000814:Aniline Compounds / Q000494:pharmacology*; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005434:Flow Cytometry; D005909:Glioblastoma / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D007201:Indicator Dilution Techniques; D020411:Oligonucleotide Array Sequence Analysis; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000077204:Temozolomide; D013844:Thiazoles / Q000494:pharmacology*; D000099157:Sphingosine Kinase
D000814:Aniline Compounds; D018906:Antineoplastic Agents, Alkylating; D053148:Caspase 3; D003606:Dacarbazine; D004791:Enzyme Inhibitors; D017853:Phosphotransferases (Alcohol Group Acceptor); D000077204:Temozolomide; D013844:Thiazoles; D000099157:Sphingosine Kinase; C530150:2-(4-hydroxyanilino)-4-(4-chlorophenyl)thiazole