WEE1 inhibition enhances sensitivity to hypoxia/reoxygenation in HeLa cells.

Hypoxia/reoxygenation (H/R) treatment reportedly induces DNA damage response (DDR), including DNA double-strand break (DSB) repair and G2 arrest, resulting in reduction of clonogenic survival. Because WEE1 plays a key role in the G2/M checkpoint along with CHK1/2, we investigated the effect of WEE1 inhibition on H/R-induced DDR using HeLa cells. The H/R treatment combined with WEE1 inhibitor abrogated G2 arrest, subsequently leading to the cells entering the M phase, and finally resulting in mitotic catastrophe after prolonged mitosis. Colony-forming assay showed an enhanced decrease in the surviving fraction and the focus formation of BRCA1 was significantly reduced. We demonstrate for the first time that WEE1 inhibition enhances H/R-induced cell death accompanied by mitotic catastrophe and that the process may be mediated by homologous recombination.