Ibuprofen and diclofenac led to cell cycle arrest at different checkpoints.

<p>Human glioma cell lines HTZ-349 (A), A172 (B), and U87MG (C) were cultured in the presence of increasing concentrations of diclofenac (0.1, 0.2 mM) or ibuprofen (1, 2 mM) and respective DMSO controls. Cells were harvested for cell cycle analysis after 48 h of incubation. Proliferation was significantly reduced as measured by a reduced number of cells in S-phase in all conditions except 0.1 mM diclofenac in A172 as well as 0.1 and 0.2 mM diclofenac in HTZ-349. With diclofenac treatment, HTZ-349 and U87MG cells showed an accumulation of cells in the G2/M (U87MG) and S-phase (HTZ-349), whereas A172 arrested in the G1 phase. Ibuprofen generated accumulation of cells in the G1 phase in all cell lines. Additional treatment with 0.05–2 mM ibuprofen (D) confirmed dose-dependent accumulation of HTZ-349 in G1 accompanied by a decrease of cells in S- and G2/M-phase. Bar graphs show mean values of three independent experiments. Histograms are depicted in the supplements (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140613#pone.0140613.s002" target="_blank">S2 Fig</a>) and show representative plots of each treatment condition.