KU 55933

KU-55933 is a specific inhibitor of ATM kinase with IC50 value of 13 nM [1].

ATM can stimulate Ser473 phosphorylation of Akt and mediate its full activation in response to insulin. As an ATM inhibitor, KU-55933 significantly inhibited the increase of phospho-Akt at Ser473 in MDA-MB-453 and PC-3 cells treated with insulin and IGF-I following serum starvation. In the MTT assay, KU-55933 treatment suppressed cell proliferation by about 50% at concentration of 10 μM in MDA-MB-453 and PC-3 cells. In a panel of cell lines that have varied Akt activities, KU-55933 treatment caused cell proliferation inhibition correlated with the Akt phosphorylation. KU-55933 was also found to induce G1 cell cycle arrest through down-regulating the cyclin D1 level in MDA-MB-453 and PC-3 cells [2].

References:
[1] Hickson I, Zhao Y, Richardson C J, et al. Identification and characterization of a novel and specific inhibitor of the ataxia-telangiectasia mutated kinase ATM. Cancer research, 2004, 64(24): 9152-9159.
[2] Li Y, Yang D Q. The ATM inhibitor KU-55933 suppresses cell proliferation and induces apoptosis by blocking Akt in cancer cells with overactivated Akt. Molecular cancer therapeutics, 2010, 9(1): 113-125.