Figure 4

Cell populations expressing elevated PD-L1 levels do not acquire short-term resistance to SI-2. (A) E0771 cells were treated with either IFN-γ (24 hr) or SI-2 or DOX (72 hr) at the indicated concentrations that then sorted into PD-L1 negative and PD-L1 positive populations. (B) After allowing cells to recover from compound exposure for seven days, PD-L1 levels were assessed again by flow cytometry, revealing that PD-L1 expression returned to basal levels of expression. (C) Cells from both the PD-L1 negative and positive populations treated with either SI-2 or IFN-γ were treated again with a dose range of SI-2 or doxorubicin (DOX) after the seven day recovery period and their viability was determined by MTS assay.