BML-277

Chk2:15 nM

BML-277 is an ATP-competitive inhibitor of Chk2 that dose dependently protects human CD4+ and CD8+ T-cells from apoptosis due to ionizing radiation. BML-277 efficiently rescues both T-cell populations from radiation-induced apoptosis in a dose-dependent manner with an observed EC50 of 3?7.6 μM. The concentration of BML-277 required for radioprotection is consistent with the biochemical measurement of chk2 inhibition. Providing theKm of ATP for Chk2 is determined to be 99 μM and the Ki for BML-277 is 37 nM, and assuming that the intracellular ATP concentration is 10 mM, a 5 μM concentration of BML-277 would be expected to produce 42% inhibition of intracellular chk2[1].

DMSO:55 mg/mL

BML-277 is dissolved in DMSO and stored, and then diluted with appropriate medium before use[1]. To determine the radioprotective effect of Chk2 inhibitors, purified T-cells are incubated at 100?000 cells per well in BML-277 (102.5 nM, 1 μM, 100.5 μM, 10 μM, and 101.5 μM) or vehicle (DMSO) at varying concentrations in 96-well stripwells for 1 h. Cells are then exposed to a dose of 0 or 10 Gy gamma irradiation from a 137Cs source at a dose rate of 3.65 Gy/min and then returned to the incubator for a further 24 h. Cells are stained with Annexin V-FITC and propidium iodide, according to the manufacturers protocol. Apoptotic and surviving cells are quantitated with a FACSCalibur FACS machine. Data are reported as percent recovery-or the number of survivors from treatment groups minus the number of cells surviving in the irradiated control group divided by the number of surviving cells in the untreated control groups[1].