Potentiation of <i>in vitro</i> ara‐C cytotoxicity by ribonucleotide reductase inhibitors, cyclin‐dependent kinase modulators and the DNA repair inhibitor aphidicolin in paediatric acute myeloid leukaemia

Hubeek, Isabelle; Peters, Godefridus J.; Broekhuizen, A. J. F.; Sargent, J. M.; Gibson, Brenda; Creutzig, U.; Kaspers, Gertjan J. L.

doi:10.1111/j.1365-2141.2005.05760.x

Cited by 12 publications

(10 citation statements)

References 9 publications

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“…However, the effect of combining these two nucleoside analogues remains controversial. Combination of the two drugs showed antagonism in L1210 mouse leukemia, murine leukemic L5178 Y cell lines, and pediatric acute myeloid leukemia cells in vitro (10). The mechanism was presumed to be either that both of these drugs competed for deoxycytidine kinase (11 -13) or that ara-C reduced DAC incorporation through inducing cell cycle arrest.…”

mentioning

confidence: 99%

Effect of Cytarabine and Decitabine in Combination in Human Leukemic Cell Lines

Qin

Youssef

Jelı́nek

et al. 2007

Clinical Cancer Research

118

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Purpose: 1-h-D-Arabinofuranosylcytosine (cytarabine; ara-C) is the most active agent in myeloid leukemia. 5-Aza-2 ¶-deoxycytidine (DAC) is a cytosine analogue that inhibits DNA methylation and also has activity in myeloid leukemia.Therefore, we investigated combining these two drugs in human leukemia cell lines in vitro. Experimental Design: We initially examined the effects of ara-C and DAC on human leukemia cell lines HL60, ML-1, RAji, and Jurkat.We measured IC 50 of DAC and ara-C in these cell lines and calculated a combination index of these two drugs given either simultaneously or sequentially. In searching for mechanisms relative to epigenetic regulation for this effect, we examined DNA methylation of LINE and Alu repetitive elements as a surrogate for global genomic DNA methylation. In addition, we sorted Annexin V positive and negative cells and measured differences in LINE methylation between them. Results: The combination of DAC and ara-C showed additive induction of cell death in ML-1 and synergistic induction in HL60, Raji, and Jurkat. Sequentially, DAC followed by ara-C was a synergistic combination in all cell lines. Low-dose DAC induced more hypomethylation than high doses of the drug, whereas ara-C had no effects on methylation. The combination of ara-C with DAC either together or DAC followed by ara-C resulted in inhibition of LINE demethylation in HL60. The RIL gene, which is silenced by DNA hypermethylation, was activated by DAC, but the addition of ara-C to DAC reduced RIL gene activation. DAC treatment increased H3 Lys 9 acetylation of Alu elements, whereas ara-C had no effect, and the addition of ara-C to DAC inhibited this effect. Finally, we showed that after DAC exposure, Annexin V positive cells were more hypomethylated than AnnexinV negative cells. Conclusion: The combination of DAC and ara-C showed additive or synergistic effects on cell death in four human leukemia cell lines in vitro, but antagonism in terms of epigenetic effects. One possible explanation for these paradoxical observations is that hypomethylated cells are sensitized to cell killing by ara-C. These data suggest that DAC used in combination with ara-C has clinical potential in the treatment of acute myeloid leukemia.Epigenetics have acquired increased recognition as a driving force in human leukemia over the past few years, leading to the revival of interest in DNA methylation inhibitors as antineoplastic agents (1). 5-Aza-2 ¶-deoxycytidine (DAC) is a potent hypomethylating agent that incorporates into DNA and traps DNA methyltransferase in the form of a covalent protein -DNA adduct. As a result, cellular DNA methyltransferase is rapidly depleted, and concomitantly genomic DNA is hypomethylated during continued DNA replication, resulting in replication-dependent DNA hypomethylation. Gene inactivation (''silencing'') of tumor-suppressor, growth-inhibitory, DNA repair, and several apoptosis genes can be mediated by DNA hypermethylation of gene promoters (2 -5). DACinduced hypomethylation is associated with reac...

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confidence: 99%

Effect of Cytarabine and Decitabine in Combination in Human Leukemic Cell Lines

Qin

Youssef

Jelı́nek

et al. 2007

Clinical Cancer Research

118

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“…Favorable interactions were observed between ara-C and aphidicolin (inhibitor of DNA repair), cladribine and gemcitabine (deoxynucleoside analogs, ribonucleotide reductase inhibitors) and also with flavopiridol and UCN-01 (modulators of cyclin-dependent kinases), supporting the evaluation of these combinations in clinical trials with AML patients [67].…”

Section: Cytarabinementioning

confidence: 93%

“…dCTP is synthetized directly via the de novo pathway by ribonucleotide reductase (RR) and antagonize the formation of Ara-CTP. CTP synthetase (CTP) converts uridine triphosphate to CTP (according to Hubeek et al [67]). tions in RAS or FLT3/ITD are frequently found in association with a normal karyotype.…”

Section: Flt3/itd Is Not Attributed To In Vitro Cellular Drug Resistancementioning

confidence: 99%

Drug Resistance in Childhood Acute Myeloid Leukemia

Styczyński

2007

CPB

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Therapy results in childhood AML differ from those of ALL. The development of drug resistance is the limiting factor in the therapy of AML. Different problems of drug resistance in childhood AML, with emphasis to age and in comparison to adult AML are presented. In vitro and in vivo aspects are discussed, together with mechanisms of resistance to cytostatic drugs, focused on clinical relevance of cellular drug resistance profile and its prognostic value. Possibilities of modulation and circumvention of drug resistance are reviewed, with stress on new drugs being tested. Taking into account both children and adults, it seems that age is adversely related to therapy outcome in AML, and the percentage of patients with favorable cytogenetics decreases with age; however, age is positively correlated with multi-drug resistance and the proportion of patients with unfavorable cytogenetics. AML is considered a stem cell disease. BCRP, PGP and MRP's are preferentially expressed in leukemic stem cells, making this disease drug resistant. Cellular drug resistance in AML cells seems to be similar throughout all other age groups, however the higher the age, the worse the outcome. In childhood AML, no drug is more effective in comparison to ALL, and cellular drug resistance is partially related to chromosomal abnormalities. Pediatric AML is equally resistant as adult AML. Pediatric and adult AML, respectively, are possibly equally drug resistant on initial diagnosis and at relapse. In contrast to ALL, the prognostic value of in vitro drug resistance in childhood AML has not been well documented yet.

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“…In mut-p53 cells this regulation is abrogated, so that UCN-01 by inhibition of the G2/M checkpoint regulators, will increase DNA damage. Moreover UCN-01 will further prevent DNA repair and enhance the effect of deoxynucleoside analogues ara-C, dFdC, 5-FU [26][27][28][29][30][31], the purine analogue fludarabine [26,32] and DNA binding agents such as cisplatin, thiotepa, mitomycin C, cisplatin, melphalan and topotecan [26]. Treatment with a DNA damaging drug (cisplatin, 5FU, nucleoside analogs or radiation) prior to UCN-01 or a novel ChK1 inhibitor (SCH00766) was synergistic and induced more cell death than vice versa through abrogation of the G2/M checkpoint and was associated by reduced expression of cyclins A and B and activation of Cdk1 [33,34].…”

Section: Discussionmentioning

confidence: 99%

Effect of staurosporine and ucn-01 on gemcitabine cytotoxicity in relation to cell cycle effects and p53 status

Sigmond¹,

León²,

Kamphuis³

et al. 2012

J Cancer Ther Res

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Gemcitabine (dFdC) is an anti-cancer agent that is affected by cell cycle modulation. Staurosporine and 7-hydroxystaurosporine (UCN-01) are potent protein kinase C (PKC) inhibitors as well as inhibitors of cyclin dependent kinase 2 (cdk2) and were therefore investigated for potential synergism, cell cycle modulation, cell death induction, and the role of the p53 protein. Lovo colon cancer cell line variants with wild type and mutant p53 (Lovo 175x2) or inactive (Lovo Li) were used for this purpose. Combinations of dFdC with staurosporine were most synergistic when cells were exposed to dFdC prior to staurosporine, while for UCN-01 the simultaneous exposure was most synergistic. This synergism appeared to be related with abrogation of the cell cycle and cell cycle proteins. For dFdC (1.0 μM), a gradual time dependent increase of cells in S phase (up to 40%) was observed in all Lovo variants. Staurosporine (0.05 μM) initially induced accumulation of cells in the G 2 /M phase (after 24 hr), while 48 hr exposure showed accumulation in the S-phase. UCN-01 (0.5 μM) caused an arrest in G 0 /G 1 after 24 hr exposure, while after 48 hr cells accumulated in the S phase. Simultaneous exposure to dFdC combinations showed an average cell cycle distribution of both drugs when used alone. In sequential addition of dFdC combinations, the first drug dominated the cell cycle distribution. Synergism of gemcitabine combinations was associated with induction of cell death by UCN-01, which was 2-fold higher in Lovo 175x2 (mutant p53) compared to other Lovo variants. Additive effects in induction of cell death were observed at the simultaneous addition of dFdC and UCN-01, but exposure to dFdC prior to UCN-01 caused a 2-fold higher induction of cell death than the sum of each compound alone in Lovo 175x2 cells, in contrast to the other lines. Accumulation of cells in the G2/M phase prevented repair of DNA damage, resulting in increased apoptosis. These data demonstrate that staurosporine and UCN-01 affect dFdC cytotoxicity via modulation of the cell cycle.

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Potentiation of in vitro ara‐C cytotoxicity by ribonucleotide reductase inhibitors, cyclin‐dependent kinase modulators and the DNA repair inhibitor aphidicolin in paediatric acute myeloid leukaemia

Cited by 12 publications

References 9 publications

Effect of Cytarabine and Decitabine in Combination in Human Leukemic Cell Lines

Effect of Cytarabine and Decitabine in Combination in Human Leukemic Cell Lines

Drug Resistance in Childhood Acute Myeloid Leukemia

Effect of staurosporine and ucn-01 on gemcitabine cytotoxicity in relation to cell cycle effects and p53 status

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