Figure 4.

Synergistic effects of BA and TMZ or irradiation. LN-319 cells were exposed for 72 h to β-BA (2.2 and 10.9 µM) (A) alone or (B) in combination with either TMZ (100 or 500 µM) or irradiation (1 or 3 Gray). Metabolic activity was assessed by MTT assay and the predicted vs. observed effect at 2.2 µM was compared using the fractional product method (12). Similar studies were performed as clonogenic survival assays, with β-BA (C) alone or (D) in combination with either TMZ (100 or 500 µM) or irradiation (1 or 3 Gray). Differences of 10% of observed vs. predicted (additive) effect were considered synergistic. Data are expressed as the mean ± standard error of the mean. BA, boswellic acid; TMZ, temozolomide; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide.