Cell experiment:

For PA-1 cell clonogenic assay, growing cells are irradiated with the indicated dose of γ-radiation (2–8 Gy). Cells are subsequently cultured in the original medium for 12 h, followed by treatment of 0.4 μM PD0166285 or DMSO control for another 4 h[1].

PD0166285 is a WEE1 inhibitor and a weak Myt1 inhibitor with IC50s of 24 and 72 nM, respectively.

PD0166285 is a pyridopyrimidine class of molecule. At the cellular level, 0.5 μM PD0166285 dramatically inhibits irradiation-induced Cdc2 phosphorylation at the Tyr-15 and Thr-14 in seven of seven cancer cell lines. PD0166285 sensitizes radiation-induced cell killing in p53 mutant HT29 cells and in the E6-transfected, p53-null ovarian cancer cell line PA-1 but to a lesser extent in p53 wild-type PA-1 cells. PD0166285 abrogates irradiation-induced G2 arrest and significantly increases mitotic cell populations. Biologically, PD0166285 acts as a radiosensitizer to sensitize cells to radiation-induced cell death with a sensitivity enhancement ratio of 1.23[1].

[1]. Wang Y, et al. Radiosensitization of p53 mutant cells by PD0166285, a novel G(2) checkpoint abrogator. Cancer Res. 2001 Nov 15;61(22):8211-7.