Overcoming S-Phase Checkpoint-Mediated Resistance: Sequence-Dependent Synergy of Gemcitabine and SN-38 In Human Carcinoma Cell Lines*

Data Supplement

Files in this Data Supplement:

• Data Supplement - Figure S1. Assessment of SN-38 accumulation by flow microfluorimetry. A, histogram showing cell fluorescence after treatment of Ovcar-5 cells with diluent (DMSO) or 10 µM SN- 38. B, increase in mean fluorescence intensity as a function of SN-38 concentration. C, time course of SN-38 uptake into cells assessed by measuring mean fluorescence intensity every 10 sec after addition of 10 µM SN-38 to cells in a temperature controlled 37 �C tube holder.
• Data Supplement - Figure S2. Cell cycle effects of SN-38 and gemcitabine in BxPC-3 cells. Histograms show DNA content after treatment with 40 nM gemcitabine, 10 nM SN-38 or both drugs simultaneously for 24 h.
• Data Supplement - Figure S3. Synergy of sequential gemcitabine and SN-38 in BxPC-3 cells. A, BxPC-3 cells were treated for 24 h with diluent or SN-38, washed and treated for another 24 h with diluent or gemcitabine using a fixed molar ratio of 8.33:1 (gemcitabine:SN-38). At the end of the incubation, cells were washed and incubated in drug-free medium until colonies formed. Data from the same experiment are plotted as a function of either SN-38 or gemcitabine concentration. Error bars, � S.D. from triplicate plates. Right panel indicates CI as a function of drug effects. Circles indicate CI calculated from data in left and middle panels under the assumption that effects are mutually exclusive; and line represents second-order regression line calculated from data points. Synergy is indicated by CI < 1, whereas antagonism is indicated by CI > 1. B, BxPC-3 cells were treated for 24 h with diluent or gemcitabine, washed and treated for another 24 h with diluent or SN-38 at a fixed SN-38:gemcitabine ratio of 1:6.
• Data Supplement - Figure S4. Cell cycle effects of sequential SN-38 and gemcitabine treatment in BxPC-3 cells. A, histograms showing DNA content after treatment with 10 nM SN-38 for 24 h followed by fixation and PI staining. Alternatively, cells were treated with 10 nM SN-38 for 24 h, washed,and incubated in drug-free medium or 40 nM gemcitabine for 24 h before fixation. B, histograms showing DNA content after treatment with 40 nM gemcitabine for 24 h. Alternatively, cells were treated with gemcitabine for 24 h, washed, and incubated in drug-free medium or 10 nM SN-38 for 24 h.