Catherine J Drummond

Karolinska Institutet, Solna, Stockholm, Sweden

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Publications (6)25.2 Total impact

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    ABSTRACT: Nutlin-3 selectively activates p53 by inhibiting the interaction of this tumor suppressor with its negative regulator murine double minute 2 (mdm2), while trichostatin A (TSA) is one of the most potent histone deacetylase (HDAC) inhibitors currently available. As both Nutlin-3 and TSA increase the levels of the cell cycle inhibitor p21(cip1/waf1) in cells, we investigated whether a combination of these compounds would further augment p21 levels. Contrary to expectations, we found that short-term exposure to Nutlin-3 and TSA in combination did not have an additive effect on p21 expression. Instead, we observed that activation of p53 prevented the ability of TSA to increase p21 levels. Furthermore, TSA inhibited Nutlin-3-induced expression of p53-dependent mRNAs including P21. This negative effect of TSA on Nutlin-3 was significantly less pronounced in the case of hdm2, another p53 downstream target. Aside from suggesting a model to explain these incompatible effects of Nutlin-3 and TSA, we discuss the implications of our findings in cancer therapy and cell reprogramming.
    Cell Death & Disease 03/2013; 4(3):e533. DOI:10.1038/cddis.2013.61 · 5.18 Impact Factor
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    ABSTRACT: Whilst small molecule inhibitors of class I/II histone deacetylases (HDACs) have been approved for cancer treatment, inhibitors of the sirtuins (a family of class III HDACs) still require further validation and optimization to enter clinical trials. Recent studies demonstrate that tenovin-6, a small molecule inhibitor of sirtuins SirT1 and SirT2, reduces tumor growth in vivo and eliminates leukemic stem cells in a murine model for chronic myelogenous leukemia. Here we describe a tenovin analog, tenovin-D3, that preferentially inhibits sirtuin SirT2 and induces predicted phenotypes for SirT2 inhibition. Unlike tenovin-6 and in agreement with its weak effect on SirT1 (a p53 deacetylase), tenovin-D3 fails to increase p53 levels or transcription factor activity. However, tenovin-D3 promotes expression of the cell cycle regulator and p53 target p21(WAF1/CIP1) (CDKN1A) in a p53-independent manner. Structure-activity relationship studies strongly support that tenovin-D3's ability to inhibit SirT2 contributes to this p53-independent induction of p21. Tenovin-D3's ability to increase p21 mRNA and protein levels is shared with class I/II HDAC inhibitors currently used in the clinic and therefore suggests that SirT2 inhibition and class I/II HDAC inhibitors have similar effects on cell cycle progression.
    Molecular Cancer Therapeutics 01/2013; 12(4). DOI:10.1158/1535-7163.MCT-12-0900 · 6.11 Impact Factor
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    ABSTRACT: Structure-activity relationships for the MDM2-p53 inhibitory activity of a series of A-ring substituted 2-N-benzyl-3-(4-chlorophenyl)-3-(1-(hydroxymethyl)cyclopropyl)methoxy)isoindolinones have been investigated, giving rise to compounds with improved potency over their unsubstituted counterparts. Isoindolinone A-ring substitution with a 4-chloro group for the 4-nitrobenzyl, 4-bromobenzyl and 4-cyanobenzyl derivatives (10a-c) and substitution with a 6-tert-butyl group for the 4-nitrobenzyl derivative (10j) were found to confer additional potency. Resolution of the enantiomers of 10a showed that potent MDM2-p53 activity resided in the (-)-enantiomer ((-)-10a; IC(50)=44 ± 6 nM). The cellular activity of key compounds has been examined in cell lines with defined p53 and MDM2 status. Compounds 10a and (-)-10a increase p53 protein levels, activate p53-dependent MDM2 and p21 transcription in MDM2 amplified cells, and show improved selectivity for growth inhibition in wild type p53 cell lines over the parent compound.
    Bioorganic & medicinal chemistry letters 08/2011; 21(19):5916-9. DOI:10.1016/j.bmcl.2011.07.084 · 2.33 Impact Factor
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    ABSTRACT: Inhibition of the MDM2-p53 interaction has been shown to produce an antitumor effect, especially in MDM2 amplified tumors. The isoindolinone scaffold has proved to be versatile for the discovery of MDM2-p53 antagonists. Optimization of previously reported inhibitors, for example, NU8231 (7) and NU8165 (49), was guided by MDM2 NMR titrations, which indicated key areas of the binding interaction to be explored. Variation of the 2-N-benzyl and 3-alkoxy substituents resulted in the identification of 3-(4-chlorophenyl)-3-((1-(hydroxymethyl)cyclopropyl)methoxy)-2-(4-nitrobenzyl)isoindolin-1-one (74) as a potent MDM2-p53 inhibitor (IC(50) = 0.23 ± 0.01 μM). Resolution of the enantiomers of 74 showed that potent MDM2-p53 activity primarily resided with the (+)-R-enantiomer (74a; IC(50) = 0.17 ± 0.02 μM). The cellular activity of key compounds has been examined in cell lines with defined p53 and MDM2 status. Compound 74a activates p53, MDM2, and p21 transcription in MDM2 amplified cells and shows moderate selectivity for wild-type p53 cell lines in growth inhibition assays.
    Journal of Medicinal Chemistry 02/2011; 54(5):1233-43. DOI:10.1021/jm1011929 · 5.48 Impact Factor
  • Molecular Cancer Therapeutics 12/2009; 8(Supplement 1):A154-A154. DOI:10.1158/1535-7163.TARG-09-A154 · 6.11 Impact Factor
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    Catherine Drummond
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    ABSTRACT: SN 28049 is a novel DNA intercalating anti-cancer drug developed at the Auckland Cancer Society Research Centre as part of ongoing research into topoisomerase II poisons with high activity against solid tumours. SN 28049 was curative against murine Colon 38 tumours, a model of colorectal adenocarcinoma which is generally unresponsive to topoisomerase II poisons (1), while two clinically used topoisomerase II poisons, doxorubicin and etoposide, were respectively moderately active and inactive against this tumour. The aim of this thesis was to use human tumour cell lines in order to develop an understanding of the mechanism of anti-tumour activity of SN 28049. Topoisomerase II poisons induce DNA double strand breaks which signal through multiple pathways, and two of these, the γ-phosphorylation of histone H2AX (γ-H2AX) and the induction of p53 protein were investigated in HCT 116 colorectal carcinoma cells and in NZM3, NZM6 and NZM52 melanoma cells. SN 28049 induced only a small increase in γ- H2AX phosphorylation, comparable to that mediated by doxorubicin and etoposide. However, a low concentration of SN 28049 (25 nM) stimulated p53 protein expression in HCT 116 cells to levels in excess of those observed in response to doxorubicin or etoposide. The activation of p53 by SN 28049 cells was investigated using the HCT 116 line and an isogenic line lacking p53 expression. As assessed by expression of the representative p53 transcriptional targets FAS, p21WAF1 and survivin, SN 28049 was considerably more active than doxorubicin or etoposide in stimulating the p53 pathway. However, there was little evidence of SN 28049 inducing either G1 arrest or apoptosis in these cells. SN 28049 instead induced p53-dependent G1 tetraploid arrest following mitotic failure in the absence of cell division. In response to a five-hour drug exposure and further growth in the absence of drug, HCT 116 p53 +/+ cells arrested with a ‘4N’ DNA content, expressing high levels of G1-phase cyclin E. At later times, senescence associated β-galactosidase (SA-β-Gal) activity increased, indicative of senescence. Under similar conditions, HCT 116 p53 -/- cells continued cycling with a DNA content of >4N. In contrast, doxorubicin added under similar conditions to HCT 116 p53 +/+ cells caused cycle arrest with an ‘8N’ DNA content and signs of senescence, while etoposide induced only signs of senescence. The activity of SN 28049 and a series of its analogues was also compared to that of doxorubicin and etoposide in both the HCT 116 p53 +/+ and p53 -/- lines using growth inhibition assays. When cells were cultured at a density that allows exponential growth, SN 28049 selectively inhibited HCT 116 cells expressing wild-type p53, and the selectivity was related to potency. However, responses to SN28049 were not distinguished qualitatively from doxorubicin and etoposide. In contrast, under conditions of high cell density, SN28049 and several active analogues maintained selectivity for HCT 116 p53 +/+ over p53 -/- cells while doxorubicin and etoposide lost their selectivity. The ability of SN 28049 to activate p53 was retained at high cell density. It is concluded that SN28049 has two cellular actions. The first, shared with doxorubicin and etoposide, is mediated by topoisomerase II-induced DNA damage, is cell cycle non-specific and leads to cell cycle arrest. The second, which is unique to SN28049 and is most easily observed in a cell line (HCT 116) growing at high cell density to ensure minimal expression of active topoisomerase II, involves bypass of mitosis and entry into a G1 tetraploid phase and is characterised by high expression of p53 and its downstream products. It is hypothesised that this second cellular action could explain the high in vivo activity of SN 28049.

Publication Stats

53 Citations
25.20 Total Impact Points

Institutions

  • 2013
    • Karolinska Institutet
      • Department of Microbiology, Tumor and Cell Biology (MTC)
      Solna, Stockholm, Sweden
  • 2011
    • Newcastle University
      • Northern Institute for Cancer Research
      Newcastle-on-Tyne, England, United Kingdom