Cyclopentenyl cytosine-induced activation of deoxycytidine kinase increases gemcitabine anabolism and cytotoxicity in neuroblastoma.

Abstract

The effect of the CTP synthetase inhibitor cyclopentenyl cytosine (CPEC) on the metabolism and cytotoxicity of 2',2'-difluorodeoxycytidine (dFdC, gemcitabine) and the expression and activity of deoxycytidine kinase (dCK) was studied in human neuroblastoma cell lines. The cytotoxicity of dFdC and CPEC was studied in a panel of MYCN-amplified and MYCN-single-copy neuroblastoma cell lines using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide-assays. dFdC-metabolism was studied in SK-N-BE(2)c cells using [3H]-radiolabeled dFdC. dCK activity and expression were measured using enzyme assays, immunoblot and quantitative PCR, respectively. Both MYCN-amplified and MYCN-single-copy neuroblastoma cell lines were highly sensitive to dFdC, with concentration of the drug resulting in 50% effect when compared to untreated controls (ED50) values in the nanomolar range after a 3-h exposure to dFdC. There was no correlation of the observed ED50 with the dCK activity. Treatment with dFdC induced cell death in MYCN-amplified cells whereas MYCN-single-copy-cell lines underwent neuronal differentiation. Pre-incubation with CPEC significantly increased dFdC-cytotoxicity from 1.3 to 5.3-fold in 13 out of 15 cell lines. [3H]dFdC-anabolism increased 6-44 fold in SK-N-BE(2)c cells after incubation with CPEC and was paralleled by a significant increase in expression and activity of dCK. In conclusion, the combination of dFdC and CPEC is highly toxic to neuroblastoma in vitro.

• Authors: Jörgen Bierau, Albert H van Gennip, René Leen, Rutger Meinsma, Huib N Caron, André B P van Kuilenburg
• Journal: Cancer chemotherapy and pharmacology (Cancer Chemother Pharmacol) Vol. 57 Issue 1 Pg. 105-13 (Jan 2006) ISSN: 0344-5704 [Print] Germany
• PMID: 16133534 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antineoplastic Agents
• MYCN protein, human
• N-Myc Proto-Oncogene Protein
• Nuclear Proteins
• Oncogene Proteins
• Deoxycytidine
• Cytidine
• cyclopentenyl cytosine
• Deoxycytidine Kinase
• Gemcitabine

Topics

• Antineoplastic Agents (pharmacology)
• Cell Differentiation (drug effects)
• Cell Line, Tumor
• Cell Survival (drug effects)
• Cytidine (analogs & derivatives, pharmacology)
• Deoxycytidine (analogs & derivatives, pharmacology)
• Deoxycytidine Kinase (metabolism)
• Dose-Response Relationship, Drug
• Drug Synergism
• Enzyme Activation
• Humans
• Immunoblotting
• N-Myc Proto-Oncogene Protein
• Neuroblastoma (enzymology, genetics, pathology)
• Nuclear Proteins (genetics)
• Oncogene Proteins (genetics)
• Gemcitabine