Fig. 4

Bortezomib sensitized glioma cells to TMZ. U251 and U87 cells were treated with bortezomib (10 nmol/L), TMZ (200 μmol/L) or a combination of the two drugs. a Left part, viability of U251 and U87 cells was measured by MTT assay. Cell survival rates were compared among groups. Right part, on day 4 and day 2, cell proliferation inhibition rates were calculated. ^ɑP < 0.01, ^βP < 0.05, compared with 10 nmol/L bortezomib group; ^θP < 0.01, ^ФP < 0.05, compared with 200 μmol/L TMZ group; *P < 0.05; **P < 0.01. b Left part, representative images of U251 and U87 spheroids taken every 2 days (scale bar, 200 μm). Right part, growth speed represented by the fold change of surface area compared with the surface area on day 1. Fold changes (in average) from the same day were compared among the three groups. ^ɑP < 0.01, ^βP < 0.05, compared with 10 nmol/L bortezomib group; ^θP < 0.01, ^ФP < 0.05, compared with 200 μmol/L TMZ group. c Left part, representative images of cell apoptosis after 48-h treatment detected via flow cytometry. Right part, percentages of early-stage (lower right quadrant) and late-stage (upper right quadrant) apoptotic cells and their sum were compared among the three groups. d Left part, representative images of cell cycle detected via flow cytometry after 48-h treatment. Right part, percentages of cells in G_0/1 (left red sharp peak), S (middle gray flat peak), and G₂/M (right sharp peak) phase were calculated and compared among groups. *P < 0.05; **P < 0.01. All experiments were repeated at least three times. MTT 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, DMSO dimethyl sulfoxide, Bor bortezomib, TMZ temozolomide