Figure 1
Pancreatic stellate cells (PSCs) express PD-L1. (A) Human PD-L1 mRNA expression was analyzed in a panel of human PDAC cell lines, in an immortalized human pancreatic stellate cell line (Im PSCs), and in primary pancreatic stellate cells (Pri PSCs) isolated from human PDAC tumors. The relative expression was normalized to PD-L1 mRNA levels present in the Panc1 cells. PD-L1 protein expression was determined in CD18 PDAC cells, in Im PSCs and in Pri PSC #2 using HSP90 as loading control. PD-L1 and HSP90 bands from three independent experiments were quantified by densitometry and data expressed as relative protein ratios. (B) CD18 PDAC cells, Im PSCs, and Pri PSC #2 were treated with IFN-γ (0.2 μg/mL) for 24 hours. The effect on PD-L1 mRNA expression was determined by qRT-PCR and the effect on PD-L1 protein expression was determined by Western blotting. PD-L1 and HSP90 bands from three independent experiments were quantified by densitometry and data expressed as relative protein ratios. (C) Mouse PD-L1 mRNA was analyzed in a panel of mouse PDAC cell lines established from tumors arising in the KPC (Kras/p53) mouse model, in mouse Pan02 cells and in two immortalized mouse pancreatic stellate cell lines (Im mPSCs). The relative expression was normalized to mouse PD-L1 mRNA levels present in the KPC1199 cells. KPC1245 PDAC cells and Im mPSC #3 were treated with mouse IFN-γ (0.05 μg/mL) for 4 hours. The effect on mouse PD-L1 mRNA expression was determined by qRT-PCR. The gene expression results are representative of three independent experiments. Bar graphs represent means +/−S.D. *p < 0.05; **p < 0.01; ***p < 0.001 relative to control samples.
