Fig. 1

Gene expression and cell killing synergy of decitabine in combination with carboplatin. a. Effects of the combination of decitabine with platinum analogs on GFP reactivation. YB5 cells were treated daily for 4 days with a fixed dose of decitabine at 25 nM (1/2 IC50) plus 0.5 to 3 IC50 doses of carboplatin or cisplatin, respectively. GFP was measured after the end of treatment by flow cytometry analysis. Standard deviation was calculated based on two independent experiments. b–d Combination index (CI) plots of decitabine and carboplatin combinations in human cancer cell lines. The cells were treated with decitabine alone, carboplatin alone, and decitabine plus carboplatin in fixed molar ratios based on the IC50 values of each drug and incubated for 4 days. We used the ratios of 1/8, 2/8, 3/8, 4/8, 6/8, and 8/8 IC50 for decitabine and carboplatin for each respective cell line. We assessed cell viability by counting of cells excluding trypan blue. The effects of combinations were estimated using the CalcuSyn software, based on the median-effect method. CI < 1 indicates synergy, CI ~ 1 indicates additive effect, and CI > 1 means antagonism