KU55933 是一种ATM抑制剂，IC50和Ki值分别为 12.9 和 2.2 nM。它对 ATM 的选择性比对PI3K/PI4K、 DNA-PK、ATR 和 mTOR 高。

KU-55933 (ATM Kinase Inhibitor) is a potent and specific ATM inhibitor.

ATM抑制剂KU-55933比JAK2抑制剂AG490,或STAT3β的过表达更强烈地影响TRAIL介导的细胞凋亡.KU-55933抑制ATM依赖的STAT3激活,通过上调DR5表达增加TRAIL调节的凋亡,抑制STAT3和NF-κB都和下调cFLIP有关,伴随着凋亡水平上升.

KU-55933是ATM有效的特定抑制剂,IC50为13 nM,Ki值为2.2 nM。KU-55933抑制ATM,通过阻断下游TAp63α的激活,提高存活力。KU-55933剂量依赖性抑制ATM依赖的磷酸化作用,IC50为300 nM。KU-55933使HeLa细胞对电离辐射敏感。KU-55933抑制癌细胞增殖。KU-55933抑制癌细胞中生长因子诱导的Akt的磷酸化作用。KU-55933也抑制DNA-PK和PI3K,IC50分别为2.5和16.6 μM。KU-55933也抑制mTOR活性,IC50为9.3 μM。小于30 μM时,KU-58050不能抑制p53的ATM-依赖性磷酸化作用（位点为第15位丝氨酸）。KU-55933的添加对UV-诱导的H2AX（位点为第139位丝氨酸）,NBS1（位点为第343为丝氨酸）,CHK1（位点为第345位丝氨酸）及SMC1（位点为第966位丝氨酸）没有明显作用效果。

Purified enzyme assays: ATM for use in the in vitro assay is obtained from HeLa nuclear extract by immunoprecipitation with rabbit polyclonal antiserum raised to the COOH-terminal 400 amino acids of ATM in buffer containing 25 mM HEPES (pH 7.4), 2 mM MgCl2, 250 mM KCl, 500 μM EDTA, 100 μM Na3VO4, 10% v/v glycerol, and 0.1% v/v Igepal. ATM-antibody complexes are isolated from nuclear extract by incubating with protein A-Sepharose beads for 1 hour and then through centrifugation to recover the beads. In the well of a 96-well plate, ATM-containing Sepharose beads are incubated with 1 μg of substrate glutathione S-transferase–p53N66 (NH2-terminal 66 amino acids of p53 fused to glutathione S-transferase) in ATM assay buffer [25 mM HEPES (pH 7.4), 75 mM NaCl, 3 mM MgCl2, 2 mM MnCl2, 50 μM Na3VO4, 500 μM DTT, and 5% v/v glycerol] at 37 °C in the presence or absence of inhibitor. After 10 minutes with gentle shaking, ATP is added to a final concentration of 50 μM and the reaction continued at 37 °C for an additional 1 hour. The plate is centrifuged at 250 × g for 10 minutes (4 °C) to remove the ATM-containing beads, and the supernatant is removed and transferred to a white opaque 96-well plate and incubated at room temperature for 1.5 hours to allow glutathione S-transferase-p53N66 binding. This plate is then washed with PBS, blotted dry, and analyzed by a standard ELISA technique with a phospho-serine 15 p53 antibody. The detection of phosphorylated glutathione S-transferase-p53N66 substrate is performed in combination with a goat antimouse horseradish peroxidase-conjugated secondary antibody. Enhanced chemiluminescence solution is used to produce a signal and chemiluminescent detection is carried out.

U2OS cells are exposed to ionizing radiation (3, 5, or 15 Gy) or UV (5 or 50 J/m2) and the ATM response determined by Western blot analysis of p53 serine 15 phosphorylation and stabilization of wild-type p53. Whole cell extracts are obtained from each time point, proteins separated by SDS-PAGE, and the ATM-specific increase in phosphorylated serine 15 measured with a p53 phospho-serine 15 specific antibody. Overall p53 stabilization with time is also observed with a p53-specific antibody (DO-1). Similarly, for studying ATM-dependent phosphorylations on H2AX, CHK1, NBS1, and SMC1, the following antibodies are used: CHK1 phospho-serine 345 and NBS1 phospho-serine 343 antibodies. Histone H2A (H-124) and CHK1 antibodies are also used, as well as SMC1 and SMC1 phospho-serine 966 antibodies. For determination of a cellular IC50 for KU-55933, the peak response time for p53 serine 15 phosphorylation of 2 hours is used to monitor inhibition of ATM. KU-55933 is titrated onto cells and preincubated for 1 hour before ionizing radiation. Using scanning densitometry, the percentage inhibition relative to vehicle control is calculated, and the IC50 value is calculated as for the in vitro determinations.(Only for Reference)

587871-26-9

C21H17NO3S2

395.49

ATM Kinase Inhibitor

Ethanol:19.8 mg/mL (50 mM)
DMSO:39.6 mg/mL (100 mM)
Powder: -20°C for 3 years
In solvent: -80°C for 2 years