Figure 2

MYC promotes survival in antiestrogen resistant cells. A, Western blot, reduced MYC in LCC9 cells at 48 h with MYC siRNA compared to control siRNA. Actin is a loading control. B, Quantitation of MYC in in LCC9 cell show 60% reduction in MYC siRNA transfected cells compared with control siRNA. C, MYC siRNA interacted additively (RI = 1.11) with ICI in inhibiting cell number in LCC1 but not in LCC9 cells. Bars,mean ± SE of relative cell number (normalized to vehicle controls) for a representative experiment performed in sextuplicate. ANOVA, p < 0.001; *p < 0.05 for treatment versus control for respective cell lines. ^, p < 0.05 for LCC1 versus LCC9 cells with MYC siRNA + ICI. D, LCC9 cells showed increased sensitivity to 10058-F4compared with LCC1 cells at 48 h. Points, mean of cell number; bars, ±SE. E, 10058-F4 or ICI alone or the combination for 48 h inhibit cell number in LCC1. In LCC9 cells, RI = 1.51, suggest a modest synergistic interaction between ICI and 10058-F4; ANOVA, p < 0.001; *p < 0.05 for treatment versus control for respective cell lines. ^, p < 0.05 for ICI + 10058-F4 versus 10058-F4. F, Western blot show decrease in MYC, MAX, BCL2 and an increase in cleaved CASP7 , with 10058-F4 (MI: MYC inhibitor) or ICI + 10058-F4 (C: combination) compared with vehicle (V) alone or with ICI alone (I) treatment (48 h). G, Annexin V-FITC (apoptosis) in LCC1 and LCC9 cells with vehicle, ICI , 10058-F4 , or ICI + 10058-F4 (combination). ANOVA, p < 0.001; *p < 0.05 for indicated treatment versus vehicle control for respective cells lines. Paclitaxel, a positive control for apoptosis. H, Dot plots showcells positive for annexin-V-FITC (x-axis) and propidium iodide (PI; y-axis).