Phosphorylation of deoxycytidine kinase on Ser-74: Impact on kinetic properties and nucleoside analog activation in cancer cells

Amsailale, Rachid; Neste, Éric Van Den; Arts, Angélique; Starczewska, Eliza; Bontemps, Françoise; Smal, Caroline

doi:10.1016/j.bcp.2012.03.022

Cited by 14 publications

(21 citation statements)

References 40 publications

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“…The first mechanism reported to control dCK activity was retro-inhibition by dCTP, although its physiological relevance is questionable [4][5][6]. Thereafter, several studies [7][8][9][10] suggested that dCK activity could be regulated by posttranslational modification, which was definitively confirmed by our group.…”

Section: Introductionsupporting

confidence: 62%

Protein phosphatase 2A regulates deoxycytidine kinase activity via Ser‐74 dephosphorylation

et al. 2014

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Edited by Zhijie Chang Keywords:Deoxycytidine kinase Nucleoside analog Ser-74 phosphorylation Protein phosphatase Ser/Thr protein phosphatase 2A a b s t r a c t Deoxycytidine kinase (dCK) is a critical enzyme for activation of anticancer nucleoside analogs. Its activity is controlled via Ser-74 phosphorylation. Here, we investigated which Ser/Thr phosphatase dephosphorylates Ser-74. In cells, the PP1/PP2A inhibitor okadaic acid increased both dCK activity and Ser-74 phosphorylation at concentrations reported to specifically target PP2A. In line with this, purified PP2A, but not PP1, dephosphorylated recombinant pSer-74-dCK. In cell lysates, the Ser-74-dCK phosphatase activity was found to be latent, Mn 2+ -activated, responsive to PP2A inhibitors, and diminished after PP2A-immunodepletion. Use of siRNAs allowed concluding definitively that PP2A constitutively dephosphorylates dCK in cells and negatively regulates its activity.

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Section: Introductionsupporting

confidence: 62%

Protein phosphatase 2A regulates deoxycytidine kinase activity via Ser‐74 dephosphorylation

et al. 2014

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“…Using fludarabine at 1 μM and cladribine at 0.1 μM, we verified that a 24 h-incubation in the presence of aphidicolin modified neither their accumulation under triphosphate derivatives, nor their incorporation into nucleic acids (results not shown), confirming our previous results at shorter time points [10]. We thus deduced that increase of purine analog-induced DNA damage by aphidicolin could not be explained by higher activation of these drugs.…”

Section: Resultssupporting

confidence: 87%

“…This finding led us to postulate that combination of nucleoside analogs with drugs like aphidicolin might enhance their conversion into nucleoside analog triphosphate and thereby their effectiveness. However, increase of dCK activity in CLL cells through Ser-74 phosphorylation was found to augment the activation of pyrimidine analogs, but not of purine analogs [10]. Yet, we observed in preliminary experiments that aphidicolin potentiated the cytotoxicity of fludarabine and cladribine in primary CLL cells, suggesting a still unidentified mechanism of sensitization to purine analogs.…”

Section: Introductionmentioning

confidence: 76%

“…Aphidicolin was used at 3 μM, a concentration that was found to increase dCK activity by 2- to 3-fold in CLL cells [9, 10]. At this concentration, aphidicolin alone induced negligible cytotoxicity, the loss of CLL cell viability being 5.6 ± 0.9 % after 4 days ( n = 47).…”

Section: Resultsmentioning

confidence: 99%

“…The influence of aphidicolin on the metabolism of fludarabine or cladribine in CLL cells was analyzed as previously described, using 3 H-labeled purine analogs [10]. …”

Section: Methodsmentioning

confidence: 99%

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Targeting DNA repair with aphidicolin sensitizes primary chronic lymphocytic leukemia cells to purine analogs

et al. 2016

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Purine analogs are among the most effective chemotherapeutic drugs for the treatment of chronic lymphocytic leukemia (CLL). However, chemoresistance and toxicity limit their clinical use. Here, we report that the DNA polymerase inhibitor aphidicolin, which displayed negligible cytotoxicity as a single agent in primary CLL cells, markedly synergizes with fludarabine and cladribine via enhanced apoptosis. Importantly, synergy was recorded regardless of CLL prognostic markers. At the molecular level, aphidicolin enhanced purine analog-induced phosphorylation of p53 and accumulation of γH2AX, consistent with increase in DNA damage. In addition, aphidicolin delayed γH2AX disappearance that arises after removal of purine analogs, suggesting that aphidicolin causes an increase in DNA damage by impeding DNA damage repair. Similarly, aphidicolin inhibited UV-induced DNA repair known to occur primarily through the nucleotide excision repair (NER) pathway. Finally, we showed that fludarabine induced nuclear import of XPA, an indispensable factor for NER, and that XPA silencing sensitized cell lines to undergo apoptosis in response to fludarabine. Together, our data indicate that aphidicolin potentiates the cytotoxicity of purine analogs by inhibiting a DNA repair pathway that involves DNA polymerases, most likely NER, and provide a rationale for manipulating it to therapeutic advantage.

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Clofarabine: Structure, Mechanism of Action, and Clinical Pharmacology

Parker

Gandhi

2017

Chemotherapy for Leukemia

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Phosphorylation of deoxycytidine kinase on Ser-74: Impact on kinetic properties and nucleoside analog activation in cancer cells

Cited by 14 publications

References 40 publications

Protein phosphatase 2A regulates deoxycytidine kinase activity via Ser‐74 dephosphorylation

Protein phosphatase 2A regulates deoxycytidine kinase activity via Ser‐74 dephosphorylation

Targeting DNA repair with aphidicolin sensitizes primary chronic lymphocytic leukemia cells to purine analogs

Clofarabine: Structure, Mechanism of Action, and Clinical Pharmacology

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