NU 7026  (Synonyms: LY293646)

Mammalian DNA-PK (500 ng/μL) is isolated from HeLa cell nuclear extract after chromatography using Q-Sepharose, S-Sepharose, and Heparin agarose. DNA-PK (250 ng) activity is measured at 30°C, in a final volume of 40 μL, in buffer containing 25 mM HEPES (pH 7.4), 12.5 mM MgCl₂, 50 mM KCl, 1 mM DTT, 10% v/v Glycerol, 0.1% w/v NP-40, and 1 mg of the substrate GST-p53N66 (the NH2-terminal 66 amino acid residues of human wild-type p53 fused to glutathione S-transferase) in polypropylene 96-well plates. To the assay mix, varying concentrations of inhibitor (in DMSO at a final concentration of 1% v/v) are added. After 10 min of incubation, ATP is added to give a final concentration of 50 μM, along with a 30-mer double-stranded DNA oligonucleotide (final concentration of 0.5 ng/mL), to initiate the reaction. After 1 h with shaking, 150 μL of PBS are added to the reaction, and 5 μL are then transferred to a 96-well opaque white plate containing 45 μL of PBS per well, where the GSTp53N66 substrate is allowed to bind to the wells for 1 h. To detect the phosphorylation event on the serine 15 residue of p53 elicited by DNA-PK, a p53 phosphoserine-15 antibody is used in a basic ELISA procedure. An antirabbit horseradish peroxidase-conjugated secondary antibody is then used in the ELISA before the addition of chemiluminescence reagent to detect the signal as measured by chemiluminescent counting via a TopCount NXT^[1].

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

I83 cells are plated in RPMI 1640 medium with 10% FBS (1.5×10⁵ cells/mL) and treated with vehicle (DMSO), 5 μM CLB, CLB IC₅₀, 10 μM NU7026, or the combination of both drugs for 0, 6, 24, and 48 h. Cell cycle distribution, apoptosis, DNA-PK phosphorylation, and γH2AX determination are determined, and they are expressed as a percentage of cells in each phase of the cycle. DNA content is analyzed with a FACSCalibur flow cytometer equipped with CellQuest software^[2].

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

Mice^[3]
Female BALB/c mice are used. NU7026 is formulated in 10% DMSO and 5% Tween 20 in saline for i.p. and perorally (p.o.) administration at 20 and 50 mg/kg, respectively. For i.v. dosing at 5 mg/kg, NU7026 is formulated in 10% ethanol, 25% PEG 200 and 5% Tween 20 in saline. Control animals receive the vehicle alone. Groups of three mice are injected per time point. Blood is collected by cardiac puncture following transient anaesthesia with halothane at 0.083, 0.25, 0.5, 1, 2, 4, 6, and 24 h post administration. Following centrifugation at 1500 g for 2 min to obtain plasma, samples are stored at −20°C until analysis. For urinary excretion studies, NU7026 is administered at 5 mg/kg i.v. Urine is collected over 24 h in metabolic cages, and stored at −20°C until required.

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

• [1]. Veuger SJ, et al. Radiosensitization and DNA repair inhibition by the combined use of novel inhibitors of DNA-dependent protein kinase and poly(ADP-ribose) polymerase-1. Cancer Res. 2003 Sep 15;63(18):6008-15.  [Content Brief]

  [2]. Amrein L, et al. Chlorambucil cytotoxicity in malignant B lymphocytes is synergistically increased by 2-(morpholin-4-yl)-benzo[h]chomen-4-one (NU7026)-mediated inhibition of DNA double-strand break repair via inhibition of DNA-dependent protein kinase. J  [Content Brief]

  [3]. Nutley BP, et al. Preclinical pharmacokinetics and metabolism of a novel prototype DNA-PK inhibitor NU7026. Br J Cancer. 2005 Oct 31;93(9):1011-8.  [Content Brief]

  [4]. Ciszewski WM, et al. Interleukin-4 enhances PARP-dependent DNA repair activity in vitro. J Interferon Cytokine Res. 2014 Sep;34(9):734-40.  [Content Brief]