Cell experiment:

Cells are seeded in 96-well plates at a predetermined optimal cell density to ensure exponential growth for duration of the assay. After a 24 h preincubation, growth medium is replaced with experimental medium containing the appropriate drug concentrations or 0.1% (v/v) vehicle control. After a 48 h incubation, cell proliferation is estimated using the sulforhodamine B colorimetric assay and expressed as the mean ± SE for six replicates as a percentage of vehicle control (taken as 100%). Experiments are performed independently at least three times. Statistical analyses are performed using a two-tailed Student's t test. P< 0.05 is considered to be statistically significant[2].

Animal experiment:

Four to six weeks old athymic CD-1 female mice are acclimatized for at least one week before use. The mice are injected sub-cutaneously with 2×106 D54-ATMR cells in each flank. Tumors are allowed to grow to the size of 100-150 mm3. Mice are injected intraperitoneally with vehicle control (DMSO), CGK-733, KU-55933 (25 mg/kg) or irradiated with 5 Gy to each flank. Bioluminescence is acquired on Xenogen IVIS Spectrum system after injecting 400 μg/100 μL of D-luciferin at baseline (-3h) as well as 1, 4, and 8 hours after drug administration[3].

CGK733 is an inhibitor of kinase ATM and ATR with IC50 value of ~200 nM [1].
Ataxia telangiectasia mutated (ATM) is a serine/threonine kinase which plays pivotal role in DNA repair and cell cycle checkpoints. And when in hypoxia circumstance, loss of ATM-related (ATR) kinase induces the decreasing of HIF-1 DNA binding, which consequently affects GLUT-1 and CAIX expression in the protein level. The components of ATM and ATR regulated signaling pathways which enhances cellular sensitivity to chemo- and radiotherapy thus provide attractive pharmacological targets [2, 3].
CGK733 selectively inhibited ATM and ATR kinase activities and blocked their checkpoint signaling pathways. Treated HEK-293 cells with GSK733 would increase the sensitivity of cells to radiotherapy [1]. When tested with HBV-positive HCC cell line HepG2.2.15, CGK733 treatment significantly increased the cells sensitivity to taxol via inducing the formation of multinucleated cells [2]. Treated with CGK733, senescent breast, lung, and colon carcinoma cells were induced to undergo cell death [4]. CGK733 treated tumor cells could enhance the sensitivity to radio therapy via inhibiting DNA repair and cell cycle checkpoints of tumor cells [5]. In MCF-7 breast cancer cells, CGK733 treatment induced detectable decline levels of cyclin D1 protein and reduced phosphorylated and total retinoblastoma protein (RB) which inhibited cell proliferation [3].
References:
[1].    Williams, T.M., et al., Molecular imaging of the ATM kinase activity. Int J Radiat Oncol Biol Phys, 2013. 86(5): p. 969-77.
[2].    Wang, H., et al., CGK733 enhances multinucleated cell formation and cytotoxicity induced by taxol in Chk1-deficient HBV-positive hepatocellular carcinoma cells. Biochem Biophys Res Commun, 2012. 422(1): p. 103-8.
[3].    Alao, J.P. and P. Sunnerhagen, The ATM and ATR inhibitors CGK733 and caffeine suppress cyclin D1 levels and inhibit cell proliferation. Radiat Oncol, 2009. 4(51): p. 4-51.
[4].    Crescenzi, E., et al., Ataxia telangiectasia mutated and p21CIP1 modulate cell survival of drug-induced senescent tumor cells: implications for chemotherapy. Clin Cancer Res, 2008. 14(6): p. 1877-87.
[5].    Kuroda, S., Y. Urata, and T. Fujiwara, Ataxia-telangiectasia mutated and the Mre11-Rad50-NBS1 complex: promising targets for radiosensitization. Acta Med Okayama, 2012. 66(2): p. 83-92.