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Hardcastle IR, Liu J, Valeur E, Watson A, Ahmed SU, Blackburn TJ, Bennaceur K, Clegg W, Drummond C, Endicott JA, Golding BT, Griffin RJ, Gruber J, Haggerty K, Harrington RW, Hutton C, Kemp S, Lu X, McDonnell JM, Newell DR, Noble MEM, Payne SL, Revill CH, Riedinger C, Xu Q, Lunec J. Isoindolinone inhibitors of the murine double minute 2 (MDM2)-p53 protein-protein interaction: structure-activity studies leading to improved potency. J Med Chem 2011; 54:1233-43. [PMID: 21314128 DOI: 10.1021/jm1011929] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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.
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Rodriguez-Aristegui S, Clapham KM, Barrett L, Cano C, Desage-El Murr M, Griffin RJ, Hardcastle IR, Payne SL, Rennison T, Richardson C, Golding BT. Versatile synthesis of functionalised dibenzothiophenes via Suzuki coupling and microwave-assisted ring closure. Org Biomol Chem 2011; 9:6066-74. [DOI: 10.1039/c1ob05282a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Clapham KM, Bardos J, Finlay MRV, Golding BT, Griffen EJ, Griffin RJ, Hardcastle IR, Menear KA, Ting A, Turner P, Young GL, Cano C. DNA-dependent protein kinase (DNA-PK) inhibitors: structure-activity relationships for O-alkoxyphenylchromen-4-one probes of the ATP-binding domain. Bioorg Med Chem Lett 2010; 21:966-70. [PMID: 21216595 DOI: 10.1016/j.bmcl.2010.12.047] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Revised: 12/07/2010] [Accepted: 12/08/2010] [Indexed: 10/18/2022]
Abstract
Introduction of an O-alkoxyphenyl substituent at the 8-position of the 2-morpholino-4H-chromen-4-one pharmacophore enabled regions of the ATP-binding site of DNA-dependent protein kinase (DNA-PK) to be probed further. Structure-activity relationships have been elucidated for inhibition of DNA-PK and PI3K (p110α), with N-(2-(cyclopropylmethoxy)-4-(2-morpholino-4-oxo-4H-chromen-8-yl)phenyl)-2-morpholinoacetamide 11a being identified as a potent and selective DNA-PK inhibitor (IC(50)=8 nM).
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Cano C, Barbeau OR, Bailey C, Cockcroft XL, Curtin NJ, Duggan H, Frigerio M, Golding BT, Hardcastle IR, Hummersone MG, Knights C, Menear KA, Newell DR, Richardson CJ, Smith GCM, Spittle B, Griffin RJ. DNA-Dependent Protein Kinase (DNA-PK) Inhibitors. Synthesis and Biological Activity of Quinolin-4-one and Pyridopyrimidin-4-one Surrogates for the Chromen-4-one Chemotype. J Med Chem 2010; 53:8498-507. [DOI: 10.1021/jm100608j] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Cano C, Golding BT, Haggerty K, Hardcastle IR, Peacock M, Griffin RJ. Atropisomeric 8-arylchromen-4-ones exhibit enantioselective inhibition of the DNA-dependent protein kinase (DNA-PK). Org Biomol Chem 2010; 8:1922-8. [PMID: 20449499 DOI: 10.1039/b926245h] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Substitution at the 3-position of the dibenzothiophen-4-yl ring of 8-(dibenzo[b,d]thiophen-4-yl)-2-morpholino-4H-chromen-4-one NU7441, a potent and selective DNA-dependent protein kinase (DNA-PK) inhibitor, with propyl, allyl or methyl enabled the separation by chiral HPLC of atropisomers. This is a consequence of restricted rotation about the dibenzothiophene-chromenone bond. Biological evaluation against DNA-PK of the pairs of atropisomers showed a marked difference in potency, with only one enantiomer being biologically active.
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Marchetti F, Cano C, Curtin NJ, Golding BT, Griffin RJ, Haggerty K, Newell DR, Parsons RJ, Payne SL, Wang LZ, Hardcastle IR. Synthesis and biological evaluation of 5-substituted O4-alkylpyrimidines as CDK2 inhibitors. Org Biomol Chem 2010; 8:2397-407. [DOI: 10.1039/b925481a] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Wong C, Griffin RJ, Hardcastle IR, Northen JS, Wang LZ, Golding BT. Synthesis of sulfonamide-based kinase inhibitors from sulfonates by exploiting the abrogated SN2 reactivity of 2,2,2-trifluoroethoxysulfonates. Org Biomol Chem 2010; 8:2457-64. [DOI: 10.1039/b922717b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Watson A, Liu J, Armstrong E, Blackburn T, Endicott JA, Golding BT, Griffin RJ, Lu X, Newell DR, Noble ME, Riedinger C, Lunec J, Hardcastle IR. Abstract A140: Identification of substituted isoindolinones as potent inhibitors of the MDM2-p53 protein-protein interaction. Mol Cancer Ther 2009. [DOI: 10.1158/1535-7163.targ-09-a140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The p53 tumor suppressor plays a pivotal role in the cell by reacting to stress, which may be caused by hypoxia, DNA damage, or oncogenic signalling. Activation of p53 protein results in the transcription of a number of genes that govern progression through the cell cycle, the initiation of DNA repair, and apoptosis. The activity of p53 is tightly regulated by the MDM2 protein, which is transcribed in response to p53 activation. MDM2 binds to and inactivates p53 and also ubiquitylates the MDM2-p53 complex to target it for proteosomal degradation. In normal cells the balance between active p53 and inactive MDM2-bound p53 is maintained in a negative feedback loop.
Inhibition of the MDM2-p53 protein-protein complex by small molecule inhibitors is expected to reactivate normal p53 pathways in cells overexpressing MDM2, consequently exerting an anti-cancer effect. Potent small molecule inhibitors of the MDM2-p53 interaction have been identified e.g. the Nutlins [Science 2004, 303, 844], the benzodiazepinediones and indolinones [J. Med. Chem. 2006, 49, 3759–3762]. The antitumor activities of these compounds in cellular and in vivo models are promising.
We have reported previously inhibitors of the MDM2-p53 interaction, based on an isoindolinone scaffold [J. Med. Chem. 2006, 49, 6209–6221], and SAR studies leading to compounds with improved potency e.g. NU8345A; IC50 = 171 ± 15 nM. NMR structural studies suggested that substitution of the isoindolinone A-ring may provide additional favourable interactions with the protein. A small series of examples was prepared, and 4-substitution with small hydrophobic groups was found to improve potency e.g. rac-4-methyl-3-(4-chlorophenyl)-3-((1-(hydroxymethyl) cyclopropyl)methoxy)-2-(4-nitrobenzyl)isoindolin-1-one (NU8405; IC50 = 274 ± 35 nM) and rac-4-chloro-3-(4-chlorophenyl)-3-((1-(hydroxymethyl)cyclopropyl)methoxy)-2-(4-nitrobenzyl)isoindolin-1-one (NU8406; IC50 = 143 ± 26 nM). Introduction of a 6-tert-butyl group was also found to be favourable i.e. rac-6-tert-butyl-3-(4-chlorophenyl)-3-((1-(hydroxymethyl)cyclopropyl)methoxy)-2-(4-nitrobenzyl)isoindolin-1-one (NU8399; IC50 = 152 ± 27 nM). Resolution of the enantiomers of NU8406, using chiral HPLC, gave NU8406A and NU8406B (IC50s of 43.8 ± 6.2 nM and 1.27 ± 0.08 M, respectively).
The cellular activities of key compounds have been determined and show dose dependent induction of p53 regulated genes by Western blotting. NU8406 shows selective cytotoxicity in p53wt HCT116 cells compared with the HCT116−/− line (GI50s = 9.8 ± 1.1 and 21.3 ± 3.1 M, respectively) which is comparable to Nutlin-3 (ELISA IC50 = 66.2 ± 5.7 nM; GI50s = 8.9 ± 0.5 and 38.8 ± 3.4 M, respectively).
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A140.
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Riedinger C, Endicott JA, Kemp SJ, Smyth LA, Watson A, Valeur E, Golding BT, Griffin RJ, Hardcastle IR, Noble ME, McDonnell JM. Analysis of Chemical Shift Changes Reveals the Binding Modes of Isoindolinone Inhibitors of the MDM2-p53 Interaction. J Am Chem Soc 2008; 130:16038-44. [DOI: 10.1021/ja8062088] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Murr MDE, Cano C, Golding BT, Hardcastle IR, Hummersome M, Frigerio M, Curtin NJ, Menear K, Richardson C, Smith GC, Griffin RJ. 8-Biarylchromen-4-one inhibitors of the DNA-dependent protein kinase (DNA-PK). Bioorg Med Chem Lett 2008; 18:4885-90. [DOI: 10.1016/j.bmcl.2008.07.066] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 07/16/2008] [Accepted: 07/16/2008] [Indexed: 10/21/2022]
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Griffin RJ, Henderson A, Curtin NJ, Echalier A, Endicott JA, Hardcastle IR, Newell DR, Noble MEM, Wang LZ, Golding BT. Searching for cyclin-dependent kinase inhibitors using a new variant of the cope elimination. J Am Chem Soc 2007; 128:6012-3. [PMID: 16669651 DOI: 10.1021/ja060595j] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
beta-Piperidinoethylsulfides are oxidized by m-chloroperbenzoic acid to intermediates containing both N-oxide and sulfone functions. These undergo a Cope-type elimination to a vinylsulfone that can be captured by amines to afford beta-aminoethylsulfones. When a beta-aminoethylsulfone group is linked to the 4-position of a phenyl group attached at N-2 of O6-cyclohexylmethylguanine, the resulting derivatives are inhibitors of the cyclin-dependent kinase CDK2. One of the most potent inhibitors (IC50 = 45 nM) contained a N-3-hydroxypropyl group on the aminoethylsulfonyl substituent. The crystal structure of this inhibitor bound to CDK2/cyclin A was determined and shows an unusual network of hydrogen bonds. The synthetic methodology developed can be utilized in multiple-parallel format and has numerous potential applications in medicinal chemistry.
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Marchetti F, Sayle KL, Bentley J, Clegg W, Curtin NJ, Endicott JA, Golding BT, Griffin RJ, Haggerty K, Harrington RW, Mesguiche V, Newell DR, Noble MEM, Parsons RJ, Pratt DJ, Wang LZ, Hardcastle IR. Structure-based design of 2-arylamino-4-cyclohexylmethoxy-5-nitroso-6-aminopyrimidine inhibitors of cyclin-dependent kinase 2. Org Biomol Chem 2007; 5:1577-85. [PMID: 17571187 DOI: 10.1039/b703241b] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An efficient synthesis of 2-substituted O(4)-cyclohexylmethyl-5-nitroso-6-aminopyrimidines from 6-amino-2-mercaptopyrimidin-4-ol has been developed and used to prepare a range of derivatives for evaluation as inhibitors of cyclin-dependent kinase 2 (CDK2). The structure-activity relationships (SARs) are similar to those observed for the corresponding O(6)-cyclohexylmethoxypurine series with the 2-arylsulfonamide and 2-arylcarboxamide derivatives showing excellent potency. Two compounds, 4-(6-amino-4-cyclohexylmethoxy-5-nitrosopyrimidin-2-ylamino)-N-(2-hydroxyethyl)benzenesulfonamide (7q) and 4-(6-amino-4-cyclohexylmethoxy-5-nitrosopyrimidin-2-ylamino)-N-(2,3-dihydroxypropyl)benzenesulfonamide (7s), were the most potent with IC50 values of 0.7 +/- 0.1 and 0.8 +/- 0.0 nM against CDK2, respectively. The SARs determined in this study are discussed with reference to the crystal structure of 4-(6-amino-4-cyclohexylmethoxy-5-nitrosopyrimidin-2-ylamino)-N-(2,3-dihydroxypropyl)benzenesulfonamide (7j) bound to phosphorylated CDK2/cyclin A.
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Hollick JJ, Rigoreau LJM, Cano-Soumillac C, Cockcroft X, Curtin NJ, Frigerio M, Golding BT, Guiard S, Hardcastle IR, Hickson I, Hummersone MG, Menear KA, Martin NMB, Matthews I, Newell DR, Ord R, Richardson CJ, Smith GCM, Griffin RJ. Pyranone, Thiopyranone, and Pyridone Inhibitors of Phosphatidylinositol 3-Kinase Related Kinases. Structure−Activity Relationships for DNA-Dependent Protein Kinase Inhibition, and Identification of the First Potent and Selective Inhibitor of the Ataxia Telangiectasia Mutated Kinase. J Med Chem 2007; 50:1958-72. [PMID: 17371003 DOI: 10.1021/jm061121y] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Structure-activity relationships have been investigated for inhibition of DNA-dependent protein kinase (DNA-PK) and ATM kinase by a series of pyran-2-ones, pyran-4-ones, thiopyran-4-ones, and pyridin-4-ones. A wide range of IC50 values were observed for pyranones and thiopyranones substituted at the 6-position, with the 3- and 5-positions proving intolerant to substitution. Related pyran-2-ones, pyran-4-ones, and thiopyran-4-ones showed similar IC50 values against DNA-PK, whereas the pyridin-4-one system proved, in general, ineffective at inhibiting DNA-PK. Extended libraries exploring the 6-position of 2-morpholino-pyran-4-ones and 2-morpholino-thiopyrano-4-ones identified the first highly potent and selective ATM inhibitor 2-morpholin-4-yl-6-thianthren-1-yl-pyran-4-one (151C; ATM; IC50=13 nM) and revealed constrained SARs for ATM inhibition compared with DNA-PK. One of the most potent DNA-PK inhibitors identified, 2-(4-methoxyphenyl)-6-(morpholin-4-yl)pyran-4-one (16; DNA-PK; IC50=220 nM) effectively sensitized HeLa cells to the topoisomerase II inhibitor etoposide in vitro.
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Seeberger S, Griffin RJ, Hardcastle IR, Golding BT. A new strategy for the synthesis of taurine derivatives using the ‘safety-catch’ principle for the protection of sulfonic acids. Org Biomol Chem 2007; 5:132-8. [PMID: 17164917 DOI: 10.1039/b614333d] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The safety-catch principle has been applied for the development of a new method for protecting sulfonic acids. 2,2-Dimethylsuccinic acid was reduced to 2,2-dimethylbutane-1,4-diol, which was selectively silylated to give 4-(tert-butyldiphenylsilanyloxy)-2,2-dimethylbutan-1-ol. Reaction of the latter compound with 2-chloroethanesulfonyl chloride in the presence of triethylamine afforded 4-(tert-butyldiphenylsilyloxy)-2,2-dimethylbutyl ethenesulfonate directly. The ethenesulfonate underwent Michael-type addition with secondary amines to give protected derivatives of taurine (2-aminoethanesulfonic acid). Deprotection was achieved on treatment with tetrabutylammonium fluoride, whereby cleavage of the silicon-oxygen bond led to an intermediate alkoxide that immediately cyclised to 2,2-dimethyltetrahydrofuran with liberation of a sulfonate. Pure sulfonic acids were obtained from the crude product by ion exchange chromatography on a strongly basic resin, which was eluted with aqueous acetic acid. The method developed should be generally applicable to the protection of sulfonic acids and is amenable to a multiparallel format.
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Barbeau OR, Cano-Soumillac C, Griffin RJ, Hardcastle IR, Smith GCM, Richardson C, Clegg W, Harrington RW, Golding BT. Quinolinone and pyridopyrimidinone inhibitors of DNA-dependent protein kinase. Org Biomol Chem 2007; 5:2670-7. [DOI: 10.1039/b705095j] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Aristegui SR, El-Murr MD, Golding BT, Griffin RJ, Hardcastle IR. Judicious Application of Allyl Protecting Groups for the Synthesis of 2-Morpholin-4-yl-4-oxo-4H-chromen-8-yl Triflate, a Key Precursor of DNA-Dependent Protein Kinase Inhibitors. Org Lett 2006; 8:5927-9. [PMID: 17165896 DOI: 10.1021/ol062297x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[Structure: see text] 2-morpholin-4-yl-4-oxo-4H-chromen-8-yl 2,2,2-trifluoromethanesulfonate is a key intermediate for the synthesis of the DNA-dependent protein kinase (DNA-PK) inhibitor 8-dibenzothiophen-4-yl-2-morpholin-4-yl-chromen-4-one (NU7441). Two improved methods for the synthesis of this triflate have been developed: (A) in 35% overall yield, through modification of the published route, and (B) in 15% overall yield, by a new route employing a Baker-Venkataraman rearrangement to enable generation of the chromenone scaffold. Both syntheses depend on the judicious use of allyl protecting groups.
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Hardcastle IR, Ahmed SU, Atkins H, Farnie G, Golding BT, Griffin RJ, Guyenne S, Hutton C, Källblad P, Kemp SJ, Kitching MS, Newell DR, Norbedo S, Northen JS, Reid RJ, Saravanan K, Willems HMG, Lunec J. Small-Molecule Inhibitors of the MDM2-p53 Protein−Protein Interaction Based on an Isoindolinone Scaffold. J Med Chem 2006; 49:6209-21. [PMID: 17034127 DOI: 10.1021/jm0601194] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
From a set of weakly potent lead compounds, using in silico screening and small library synthesis, a series of 2-alkyl-3-aryl-3-alkoxyisoindolinones has been identified as inhibitors of the MDM2-p53 interaction. Two of the most potent compounds, 2-benzyl-3-(4-chlorophenyl)-3-(3-hydroxypropoxy)-2,3-dihydroisoindol-1-one (76; IC(50) = 15.9 +/- 0.8 microM) and 3-(4-chlorophenyl)-3-(4-hydroxy-3,5-dimethoxybenzyloxy)-2-propyl-2,3-dihydroisoindol-1-one (79; IC(50) = 5.3 +/- 0.9 microM), induced p53-dependent gene transcription, in a dose-dependent manner, in the MDM2 amplified, SJSA human sarcoma cell line.
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Hardcastle IR, Cockcroft X, Curtin NJ, El-Murr MD, Leahy JJJ, Stockley M, Golding BT, Rigoreau L, Richardson C, Smith GCM, Griffin RJ. Discovery of potent chromen-4-one inhibitors of the DNA-dependent protein kinase (DNA-PK) using a small-molecule library approach. J Med Chem 2006; 48:7829-46. [PMID: 16302822 DOI: 10.1021/jm050444b] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Structure-activity relationships for inhibition of DNA-dependent protein kinase (DNA-PK) have been defined for substituted chromen-4-ones. For the 2-amino-substituted benzo[h]chromen-4-ones, a morpholine substituent at this position was essential for activity. Small libraries of 6- and 7-alkoxy-substituted chromen-4-ones showed that a number of 7-alkoxy-substituted chromenones displayed improved activity. Focused libraries incorporating 6-, 7-, and 8-aryl and heteroaryl substituents were prepared. In these cases, 6- and 7-substitution was disfavored, whereas 8-substitution was largely tolerated. Surprisingly, two compounds, 2-N-morpholino-8-dibenzofuranyl-chromen-4-one (NU7427, 32{38}) and the 2-N-morpholino-8-dibenzothiophenyl-chromen-4-one (NU7441, 32{26}) were excellent inhibitors (IC50 vs DNA-PK = 40 and 13 nM, respectively). The ring-saturated analogue 2-N-morpholino-8-(6',7',8',9'-tetrahydrodibenzothiophene)chromen-4-one, 36, retained potent activity (IC50 vs DNA-PK = 23 nM). The dibenzothiophene 32{38} sensitized HeLa cells to ionizing radiation in vitro, with dose modification factors of 2.5 at 10% survival being observed at 0.5 microM. The cytotoxicity of the topoisomerase II inhibitor etoposide was also potentiated.
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Walton MI, Wilson SC, Hardcastle IR, Mirza AR, Workman P. An evaluation of the ability of pifithrin-α and -β to inhibit p53 function in two wild-type p53 human tumor cell lines. Mol Cancer Ther 2005; 4:1369-77. [PMID: 16170029 DOI: 10.1158/1535-7163.mct-04-0341] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The small-molecule compound pifithrin-alpha (PFT-alpha) has been reported to inhibit p53 function and protect against a variety of genotoxic agents. We show here that PFT-alpha is unstable in tissue culture medium and is rapidly converted to its condensation product PFT-beta. Both compounds showed limited solubility with PFT-alpha precipitating out of tissue culture medium at concentrations >30 micromol/L. PFT-alpha and -beta exhibited cytotoxic effects in vitro towards two human wild-type p53-expressing tumor cell lines, A2780 ovarian and HCT116 colon (IC(50) values for both cell lines were 21.3 +/- 8.1 micromol/L for PFT-alpha and 90.3 +/- 15.5 micromol/L for PFT-beta, mean +/- SD, n = 4). There was no evidence of protection by clonogenic assay with either compound in combination with ionizing radiation. Indeed, there was some evidence that PFT-alpha enhanced cytotoxicity, particularly at higher concentrations of PFT-alpha. Neither compound had any effect on p53, p21, or MDM-2 protein expression following ionizing radiation exposure and there was no evidence of any abrogation of p53-dependent, ionizing radiation-induced cell cycle arrest. Similarly, there was no evidence of cellular protection, or of effects on p53-dependent gene transcription, or on translation of MDM-2 or p21 following UV treatment of these human tumor cell lines. In addition, there was no effect on p53 or p21 gene transactivation or p38 phosphorylation after UV irradiation of NIH-3T3 mouse fibroblasts. In conclusion, neither PFT-alpha nor -beta can be regarded as a ubiquitous inhibitor of p53 function, and caution should be exercised in the use of these agents as specific p53 inhibitors.
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Pennati M, Campbell AJ, Curto M, Binda M, Cheng Y, Wang LZ, Curtin N, Golding BT, Griffin RJ, Hardcastle IR, Henderson A, Zaffaroni N, Newell DR. Potentiation of paclitaxel-induced apoptosis by the novel cyclin-dependent kinase inhibitor NU6140: a possible role for survivin down-regulation. Mol Cancer Ther 2005; 4:1328-37. [PMID: 16170024 DOI: 10.1158/1535-7163.mct-05-0022] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Cyclin-dependent kinases (CDK) play a crucial role in the control of the cell cycle. Aberrations in the control of cell cycle progression occur in the majority of human malignancies; hence, CDKs are promising targets for anticancer therapy. Here, we define the cellular effects of the novel CDK inhibitor NU6140, alone or in association with paclitaxel, with respect to inhibition of cell proliferation and cell cycle progression and induction of apoptosis in HeLa cervical carcinoma cells and in comparison with purvalanol A. Both CDK inhibitors induced a concentration-dependent cell cycle arrest at the G2-M phase and an increase in the apoptotic rate, with a concomitant down-regulation of the antiapoptotic protein survivin, a member of the inhibitors of apoptosis protein family. Notably, the addition of NU6140 to paclitaxel-treated cells resulted in markedly increased cytotoxic effect and apoptotic response in comparison with the paclitaxel-purvalanol A combination (86 ± 11% and 37 ± 8%, respectively). Similarly, the extent of caspase-9 and caspase-3 activation in paclitaxel-NU6140–treated cells was ∼4-fold higher than after the paclitaxel-purvalanol A combination. Moreover, an almost complete abrogation of the expression of the active, Thr34-phosphorylated form of survivin was observed in cells exposed to the paclitaxel-NU6140 combination. A synergistic effect of the paclitaxel-NU6140 combination, as a consequence of survivin inhibition and increased activation of caspase-9 and caspase-3, was also observed in OAW42/e ovarian cancer line but not in the derived OAW42/Surv subline ectopically expressing survivin. Results from this study indicate that NU6140 significantly potentiates the apoptotic effect of paclitaxel, with inhibition of survivin expression/phosphorylation as the potential mechanism.
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Hardcastle IR, Ahmed SU, Atkins H, Calvert AH, Curtin NJ, Farnie G, Golding BT, Griffin RJ, Guyenne S, Hutton C, Källblad P, Kemp SJ, Kitching MS, Newell DR, Norbedo S, Northen JS, Reid RJ, Saravanan K, Willems HMG, Lunec J. Isoindolinone-based inhibitors of the MDM2-p53 protein-protein interaction. Bioorg Med Chem Lett 2005; 15:1515-20. [PMID: 15713419 DOI: 10.1016/j.bmcl.2004.12.061] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2004] [Revised: 12/17/2004] [Accepted: 12/21/2004] [Indexed: 10/25/2022]
Abstract
A series of 2-N-alkyl-3-aryl-3-alkoxyisoindolinones has been synthesised and evaluated as inhibitors of the MDM2-p53 interaction. The most potent compound, 3-(4-chlorophenyl)-3-(4-hydroxy-3,5-dimethoxybenzyloxy)-2-propyl-2,3-dihydroisoindol-1-one (NU8231), exhibited an IC50 of 5.3 +/- 0.9 microM in an ELISA assay, and induced p53-dependent gene transcription in a dose-dependent manner, in the SJSA human sarcoma cell line.
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47
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Leahy JJJ, Golding BT, Griffin RJ, Hardcastle IR, Richardson C, Rigoreau L, Smith GCM. Identification of a highly potent and selective DNA-dependent protein kinase (DNA-PK) inhibitor (NU7441) by screening of chromenone libraries. Bioorg Med Chem Lett 2005; 14:6083-7. [PMID: 15546735 DOI: 10.1016/j.bmcl.2004.09.060] [Citation(s) in RCA: 307] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2004] [Revised: 09/17/2004] [Accepted: 09/21/2004] [Indexed: 11/29/2022]
Abstract
A solution-phase multiple-parallel synthesis approach was employed for the preparation of 6-, 7- and 8-aryl-substituted chromenone libraries, which were screened as inhibitors of the DNA repair enzyme DNA-dependent protein kinase (DNA-PK). These studies resulted in the identification of 8-dibenzothiophen-4-yl-2-morpholin-4-yl-chromen-4-one (NU7441) as a highly potent and selective DNA-PK inhibitor (IC50=14 nM), exhibiting ATP-competitive inhibition kinetics.
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48
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Griffin RJ, Fontana G, Golding BT, Guiard S, Hardcastle IR, Leahy JJJ, Martin N, Richardson C, Rigoreau L, Stockley M, Smith GCM. Selective benzopyranone and pyrimido[2,1-a]isoquinolin-4-one inhibitors of DNA-dependent protein kinase: synthesis, structure-activity studies, and radiosensitization of a human tumor cell line in vitro. J Med Chem 2005; 48:569-85. [PMID: 15658870 DOI: 10.1021/jm049526a] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A diverse range of chromen-2-one, chromen-4-one and pyrimidoisoquinolin-4-one derivatives was synthesized and evaluated for inhibitory activity against the DNA repair enzyme DNA-dependent protein kinase (DNA-PK), with a view to elucidating structure-activity relationships for potency and kinase selectivity. DNA-PK inhibitory activity varied widely over the series of compounds evaluated (IC(50) values ranged from 0.19 to >10 microM), with excellent activity being observed for the 7,8-benzochromen-4-one and pyrimido[2,1-a]isoquinolin-4-one templates. By contrast, inhibitors based on the benzochromen-2-one (coumarin) or 2-aryl-7,8-benzochromen-4-one (flavone) scaffolds were less potent. Crucially, these studies revealed a very constrained structure-activity relationship at the 2-position of the benzopyranone and pyrimido[2,1-a]isoquinolin-4-one pharmacophore, with only a 2-morpholino or 2-(2'-methylmorpholino) group being tolerated at this position. More detailed biological studies conducted with the most potent inhibitor NU7163 (48; IC(50) = 0.19 microM) demonstrated ATP-competitive DNA-PK inhibition, with a K(i) value of 24 nM, and 48 exhibited selectivity for DNA-PK compared with the related enzymes ATM, ATR, mTOR, and PI 3-K (p110alpha). Compound 48 sensitized the HeLa human tumor cell line to the cytotoxic effects of ionizing radiation in vitro, a dose modification factor of 2.3 at 10% survival being observed with an inhibitor concentration of 5 microM. This study identified these structural classes as novel DNA-PK inhibitors and delineated initial structure-activity relationships against DNA-PK.
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49
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Hardcastle IR, Arris CE, Bentley J, Boyle FT, Chen Y, Curtin NJ, Endicott JA, Gibson AE, Golding BT, Griffin RJ, Jewsbury P, Menyerol J, Mesguiche V, Newell DR, Noble MEM, Pratt DJ, Wang LZ, Whitfield HJ. N2-substituted O6-cyclohexylmethylguanine derivatives: potent inhibitors of cyclin-dependent kinases 1 and 2. J Med Chem 2004; 47:3710-22. [PMID: 15239650 DOI: 10.1021/jm0311442] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The adenosine 5'-triphosphate (ATP) competitive cyclin-dependent kinase inhibitor O(6)-cyclohexylmethylguanine (NU2058, 1) has been employed as the lead in a structure-based drug discovery program resulting in the discovery of the potent CDK1 and -2 inhibitor NU6102 (3, IC(50) = 9.5 nM and 5.4 nM vs CDK1/cyclinB and CDK2/cyclinA3, respectively). The SAR for this series have been explored further by the synthesis and evaluation of 45 N(2)-substituted analogues of NU2058. These studies have confirmed the requirement for the hydrogen bonding N(2)-NH group and the requirement for an aromatic N(2)-substituent to confer potency in the series. Additional potency is conferred by the presence of a group capable of donating a hydrogen bond at the 4'-position, for example, the 4'-hydroxy derivative (25, IC(50) = 94 nM and 69 nM vs CDK1/cyclinB and CDK2/cyclinA3, respectively), 4'-monomethylsulfonamide derivative (28, IC(50) = 9 nM and 7.0 nM vs CDK1/cyclinB and CDK2/cyclinA3, respectively), and 4'-carboxamide derivative (34, IC(50) = 67 nM and 64 nM vs CDK1/cyclinB and CDK2/cyclinA3, respectively). X-ray crystal structures have been obtained for key compounds and have been used to explain the observed trends in activity.
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50
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Hollick JJ, Golding BT, Hardcastle IR, Martin N, Richardson C, Rigoreau LJM, Smith GCM, Griffin RJ. 2,6-disubstituted pyran-4-one and thiopyran-4-one inhibitors of DNA-Dependent protein kinase (DNA-PK). Bioorg Med Chem Lett 2003; 13:3083-6. [PMID: 12941339 DOI: 10.1016/s0960-894x(03)00652-8] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
6-aryl-2-morpholin-4-yl-4H-pyran-4-ones and 6-aryl-2-morpholin-4-yl-4H-thiopyran-4-ones were synthesised and evaluated as potential inhibitors of the DNA repair enzyme DNA-dependent protein kinase (DNA-PK). Several compounds in each series exhibited superior activity to the chromenone LY294002, and were of comparable potency to the benzochromenone NU7026 (IC(50)=0.23 microM). Importantly, members of both structural classes were found to be selective inhibitors of DNA-PK over related phosphatidylinositol 3-kinase-related kinase (PIKK) family members. A multiple-parallel synthesis approach, employing Suzuki cross-coupling methodology, was utilised to prepare libraries of thiopyran-4-ones with a range of aromatic groups at the 3'- and 4'-positions on the thiopyran-4-one 6-aryl ring. Screening of the libraries resulted in the identification of 6-aryl-2-morpholin-4-yl-4H-thiopyran-4-ones bearing naphthyl or benzo[b]thienyl substituents at the 4'-position, as potent DNA-PK inhibitors with IC(50) values in the 0.2-0.4 microM range.
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