Fig. 1

Effects of bortezomib on the proliferation, apoptosis, and cell cycle of glioma cells. a MTT assay measured the viability of U251 and U87 cell lines under 0 (Control, DMSO), 5, 10, 20, 40, 60, 80, and 100 nmol/L bortezomib treatment. The cell proliferation inhibition rate of each treatment group was compared with that of every other group detected on the same day. ^ɑP < 0.01, ^βP < 0.05, compared with the 5 nmol/L group; ^εP < 0.01, ^eP < 0.05, compared with 10 nmol/L group; ^#P < 0.01, ^πP < 0.05, compared with 20 nmol/L group; ^ϑP < 0.01, ^δP < 0.05, compared with 40 nmol/L group; ^θP < 0.01, ^ФP < 0.05, compared with 60 nmol/L group. b Day 2 and Day 4 IC₅₀ of bortezomib in U251 and U87 cells were calculated with the method of “log(inhibitor) vs. normalized response-Variable slope” using GraphPad Prism 7.0. c Left part, representative images of cell apoptosis detected via flow cytometry. U251 and U87 cells were treated with 10 and 20 nmol/L bortezomib for 48 h. Right part, percentages of early-stage (lower right quadrant), late-stage (upper right quadrant), and total apoptotic cells were compared among the three groups. *P < 0.05; **P < 0.01. d Left part, representative images of cell cycle detected via flow cytometry. U251 and U87 cells were treated with 10 and 20 nmol/L bortezomib for 48 h. Right part, percentages of cells in G_0/1 (left red sharp peak), S (middle gray flat peak), and G₂/M (right sharp peak) phases were calculated and compared among groups. *P < 0.05; **P < 0.01. All experiments were repeated at least three times. DMSO dimethyl sulfoxide, IC₅₀ 50% inhibitory concentration