Fig. 1

Cytotoxic potential of BT-cisplatin combination on the isogenic pair of ovarian cancer cell lines A2780 (cisplatin-sensitive) and A2780-CDDP (cisplatin-resistant). After determining viability (PrestoBlue assay) of cells treated with combinations of BT and cisplatin, combination index (CI) values were calculated and represented as heat maps where a drug combination is synergistic (green color) if CI <0.9; additive (yellow color) if CI is between 0.9 and 1.0; and antagonistic (red color) if CI >1.0. Combination index values for A2780 and A2780-CDDP are shown in (a) and (C) respectively. Percent cytotoxicity induced by BT/cisplatin combination at synergistic ratios for A2780 (b) and A2780-CDDP (d) are shown in bar graphs. Comparisons between cisplatin alone-treated and combination-treated for each cell line were performed by Student’s t-test. All data were expressed as mean ± SD of triplicate experiments. The significance level was set at p < 0.05 as indicated by asterisk (*)