Figure 4.

Pharmacological inhibition of c-Myc by JQ1 suppresses PD-L1 expression. Immunoblotting (a) and qPCR (b and c) were performed to evaluate the expression of PD-L1 in SW1990 and BxPC-3 cells following JQ1 treatment for 48 hours at different concentrations (1.6, 3.2, and 4.8 nM). The data represent the mean ± SD of three independent experiments. *p < 0.01 when compared to the control group; #p < 0.01 when compared to the JQ1-1.6 nM group. (d–g) BxPC-3 and SW1990 xenografts from nude mice were treated intraperitoneally with control solvent or JQ1 at 25 mg/kg body weight twice daily. Each group contained five animals. Tumor weight was then measured (d and f). Representative examples of c-Myc and PD-L1 staining using BxPC-3 (e) or SW1990 (g) tumors grown in nude mice and treated with control solvent or JQ1. c-Myc⁺ and PD-L1⁺ tumor cells are shown in brown. Scale bars, 50 µm (red line at the bottom left).