2'-deoxy-5-azacytidine increases binding of cisplatin to DNA by a mechanism independent of DNA hypomethylation

Ellerhorst, JA; Frost, Philip; Abbruzzese, J. L.; Newman, RA; Chernajovsky, Yuti

doi:10.1038/bjc.1993.41

Cited by 17 publications

(10 citation statements)

References 30 publications

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“…Both CTP and UTP can moderately inhibit the activity of dCK in competition with ATP , therefore a rise in CTP and UTP might decrease the accumulation of dFdCTP. However, CDDP might also inhibit dFdC uptake of cells directly, which was already shown for 2′-deoxy-5-azacytidine (DAC), another deoxycytidine analogue (Ellerhorst et al, 1993).…”

Section: Discussionmentioning

confidence: 99%

Mechanisms of synergism between cisplatin and gemcitabine in ovarian and non-small-cell lung cancer cell lines

et al. 1999

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2′,2′-Difluorodeoxycytidine (gemcitabine, dFdC) and cis -diammine-dichloroplatinum (cisplatin, CDDP) are active agents against ovarian cancer and non-small-cell lung cancer (NSCLC). CDDP acts by formation of platinum (Pt)–DNA adducts; dFdC by dFdCTP incorporation into DNA, subsequently leading to inhibition of exonuclease and DNA repair. Previously, synergism between both compounds was found in several human and murine cancer cell lines when cells were treated with these drugs in a constant ratio. In the present study we used different combinations of both drugs (one drug at its IC 25 and the other in a concentration range) in the human ovarian cancer cell line A2780, its CDDP-resistant variant ADDP, its dFdC-resistant variant AG6000 and two NSCLC cell lines, H322 (human) and Lewis lung (LL) (murine). Cells were exposed for 4, 24 and 72 h with a total culture time of 96 h, and possible synergism was evaluated by median drug effect analysis by calculating a combination index (CI; CI < 1 indicates synergism). With CDDP at its IC 25 , the average CIs calculated at the IC 50 , IC 75 IC 90 and IC 95 after 4, 24 and 72 h of exposure were < 1 for all cell lines, indicating synergism, except for the CI after 4 h exposure in the LL cell line which showed an additive effect. With dFdC at its IC 25 , the CIs for the combination with CDDP after 24 h were < 1 in all cell lines, except for the Cls after 4 h exposure in the LL and H322 cell lines which showed an additive effect. At 72 h exposure all Cls were < 1. CDDP did not significantly affect dFdCTP accumulation in all cell lines. CDDP increased dFdC incorporation into both DNA and RNA of the A2780 cell lines 33- and 79-fold ( P < 0.01) respectively, and tended to increase the dFdC incorporation into RNA in all cell lines. In the AG6000 and LL cell lines, CDDP and dFdC induced > 25% more DNA strand breaks (DSB) than each drug alone; however, in the other cell lines no effect, or even a decrease in DSB, was observed. dFdC increased the cellular Pt accumulation after 24 h incubation only in the ADDP cell line. However, dFdC did enhance the Pt–DNA adduct formation in the A2780, AG6000, ADDP and LL cell lines (1.6-, 1.4-, 2.9- and 1.6-fold respectively). This increase in Pt–DNA adduct formation seems to be related to the incorporation of dFdC into DNA ( r = 0.91). No increase in DNA platination was found in the H322 cell line. dFdC only increased Pt–DNA adduct retention in the A2780 and LL cell lines, but decreased the Pt–DNA adduct retention in the AG6000 cell line. In conclusion, the synergism between dFdC and CDDP appears to be mainly due to an increase in Pt–DNA adduct formation possibly related to changes in DNA due to dFdC incorporation into DNA. © 1999 Cancer Research Campaign

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Section: Discussionmentioning

confidence: 99%

Mechanisms of synergism between cisplatin and gemcitabine in ovarian and non-small-cell lung cancer cell lines

et al. 1999

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“…Based on these potential mechanisms, a variety of approaches have been adopted to reverse or overcome CDDP-resistance, including demethylation (6). 5-aza-2'-deoxycytidine (5-aza-CdR), a demethylating agent, has been shown to induce demethylation by inhibiting DNA methyltransferases (DNMTs) and synergistically potentiating the cytotoxicity of CDDP due to DNA topologic changes (10,11). It was reported that treatment of ovarian and colon carcinoma xenografts with 5-aza-CdR and CDDP in vivo INTERNATIONAL JOURNAL OF ONCOLOGY 28: 497-508, 2006 497 A novel mechanism for acquired cisplatin-resistance: Suppressed translation of death-associated protein kinase mRNA is insensitive to 5-aza-2'-deoxycitidine and trichostatin in cisplatin-resistant cervical squamous cancer cells could reverse drug-resistance by restoring hMLH1 expression, which is silenced by promoter methylation (6).…”

Section: Introductionmentioning

confidence: 99%

A novel mechanism for acquired cisplatin-resistance: Suppressed translation of death-associated protein kinase mRNA is insensitive to 5-aza-2'-deoxycitidine and trichostatin in cisplatin-resistant cervical squamous cancer cells

Bai

Tanaka²,

Yukawa³

et al. 2006

Int J Oncol

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Abstract. The molecular mechanism for cisplatin (CDDP)-resistance of cancer cells has not yet been clarified, despite extensive studies. Here, we investigated whether deathassociated protein (DAP) kinase, an apoptosis modulator, was involved in CDDP-resistance by examining the ME180 human cervical squamous cancer cell line and 6 monoclonal ME180-derived CDDP-resistant subclones. Co-treatment with CDDP and 5-aza-2'-deoxycytidine (5-aza-CdR), a demethylating agent, significantly enhanced the CDDPsensitivities of the parent cells and CDDP-resistant subclones. Subsequent removal of 5-aza-CdR rapidly reversed the CDDP-sensitivity of the CDDP-resistant subclones to their original levels, whereas the parent cells retained the enhanced CDDP-sensitivity for at least 24 h. Quantitative RT-PCR revealed that the CDDP-resistant subclones expressed higher DNA methyltransferase (DNMT) mRNA levels than the parent cells, suggesting that increased DNMT expressions easily restored the CDDP-resistance of the CDDP-resistant subclones following 5-aza-CdR removal. Although the parent cells showed hypermethylation in the DAP kinase promoter region, corresponding methylated bands were not detected in 2 of the 6 CDDP-resistant subclones by methylation-specific PCR. All 6 CDDP-resistant subclones expressed higher DAP kinase mRNA levels than the parent cells, as evaluated by quantitative RT-PCR. Although DAP kinase protein expression was strongly suppressed in the parent cells and CDDP-resistant subclones, 5-aza-CdR treatment of the parent cells dosedependently stimulated the DAP kinase protein expression, and this was synergistically enhanced by inhibiting histone deacetylation via trichostatin treatment in addition to 5-azaCdR. However, DAP kinase protein expression in the CDDPresistant subclones was not stimulated by treatment with 5-aza-CdR and/or trichostatin. These results indicate that posttranscriptional translation of DAP kinase mRNA is strongly suppressed and insensitive to treatment with 5-aza-CdR and trichostatin in the CDDP-resistant subclones established from ME180 human cervical squamous cancer cells. This CDDPresistance is accompanied by molecular changes that disturb the post-transcriptional translation of the DAP kinase mRNA, and these molecular changes are transiently restored by demethylation.

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“…Additional inhibition on the RNA level might potentiate the suppression of RNR activity by AraC, gemcitabine and cisplatin. Earlier studies also indicate that synergistic interactions between cisplatin and DNMT inhibitors might be based on methylation-independent mechanisms (32,56). These data suggest that there might be other or additional mechanisms besides DNA hypomethylation enhancing cytotoxic drug activity.…”

Section: Discussionmentioning

confidence: 81%

5-Azacytidine enhances efficacy of multiple chemotherapy drugs in AML and lung cancer with modulation of CpG methylation

Füller

Klein

Schmidt

et al. 2014

International Journal of Oncology

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The DNA methyltransferase (DNMT) inhibitory drugs such as 5-azacytidine induce DNA hypomethylation by inhibiting DNA methyltransferases. While clinically effective, DNMT inhibitors are not curative. A combination with cytotoxic drugs might be beneficial, but this is largely unexplored. In the present study, we analyzed potential synergisms between cytotoxic drugs and 5-azacytidine in acute myeloid leukemia (AML) and non-small cell lung cancer (NSCLC) cells. Lung cancer and leukemia cell lines were exposed to low doses of 5-azacytidine with varying doses of cytarabine or etoposide for AML cells (U937 and HL60) as well as cisplatin or gemcitabine for NSCLC cells (A549 and HTB56) for 48 h. Drug interaction and potential synergism was analyzed according to the Chou-Talalay algorithm. Further analyses were based on soft agar colony formation assays, active caspase-3 staining and BrdU incorporation flow cytometry. To identify effects on DNA methylation patterns, we performed genome wide DNA methylation analysis using 450K bead arrays. Azacytidine at low doses was synergistic with cytotoxic drugs in NSCLC and in AML cell lines. Simultaneous exposure to 5-azacytidine with cytotoxic drugs showed strong synergistic activity. In colony formation assays these synergisms were repeatedly verified for 5-azacytidine (25 nM) with low doses of anticancer agents. 5-azacytidine neither affected the cell cycle nor increased apoptosis. 450K methylation bead arrays revealed 1,046 CpG sites in AML and 1,778 CpG sites in NSCLC cells with significant DNA hypomethylation (24-h exposure) to 5-azacytidine combined with the cytotoxic drugs. These CpG-sites were observed in the candidate tumor-suppressor genes MGMT and THRB. Additional incubation time after 24-h treatment led to a 4.1-fold increase of significant hypomethylated CpG-sites in NSCLC cells. These results suggest that the addition of DNA demethylating agents to cytotoxic anticancer drugs exhibits synergistic activity in AML and NSCLC. Dysregulation of an equilibrium of DNA methylation in cancer cells might increase the susceptibility for cytotoxic drugs.

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2'-deoxy-5-azacytidine increases binding of cisplatin to DNA by a mechanism independent of DNA hypomethylation

Cited by 17 publications

References 30 publications

Mechanisms of synergism between cisplatin and gemcitabine in ovarian and non-small-cell lung cancer cell lines

Mechanisms of synergism between cisplatin and gemcitabine in ovarian and non-small-cell lung cancer cell lines

A novel mechanism for acquired cisplatin-resistance: Suppressed translation of death-associated protein kinase mRNA is insensitive to 5-aza-2'-deoxycitidine and trichostatin in cisplatin-resistant cervical squamous cancer cells

5-Azacytidine enhances efficacy of multiple chemotherapy drugs in AML and lung cancer with modulation of CpG methylation

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