Mechanisms Mediating the Effects of γ-Tocotrienol When Used in Combination with PPARγ Agonists or Antagonists on MCF-7 and MDA-MB-231 Breast Cancer Cells
Figure 4
Isobologram analysis of combined treatment of γ-tocotrienol and PPARγ ligands on (a) MCF-7 and (b) MDA-MB-231 human breast cancer cells. Individual IC50 doses for γ-tocotrienol, PPARγ agonists (rosiglitazone and troglitazone), and PPARγ antagonists (GW9662 and T0070907) were calculated and then plotted on the -axes and -axes, respectively. The data point on the isobologram represents the actual doses of combined γ-tocotrienol and PPARγ ligands. Combined treatment of PPARγ agonists rosiglitazone and troglitazone with γ-tocotrienol was found to be antagonistic, as evidenced by the location of the data point in the isobologram being well above the line defining additive effect. In contrast, the growth inhibitory effect of combined treatment of γ-tocotrienol with PPARγ antagonists GW9662 and T0070907 was found to be synergistic, as evidenced by the location of the data point in the isobologram being well below the line defining additive effect for both cell lines.
