FIGURE 2.

PD-L1 is Frequently Downregulated in EC Tissues and Acts as a Tumor Suppressor in Aggressive EC Cells. (A) Representative immunohistochemical staining (IHC) images of PD-L1 in EC tissues and normal endometrium tissues. Scale bar, 200 μm. PD-L1 staining was mostly detected in cell cytoplasm and membrane. (B) The pie chart showing the percentages of the population with PD-L1-negative or PD-L1-positive expression in EC tissues and normal endometrium tissues, determined by IHC analysis. (C) The mean PD-L1 staining score in EC tissues and normal tissues. The mean PD-L1 staining score in EC tissues was significantly lower than that in the normal tissues. (D) PD-L1 protein levels in a normal endometrial cell line (EM) and human aggressive EC cell lines were determined by western blot analysis. (E) A gain-of-function screening for PD-L1 that affects the proliferation, apoptosis, migration and invasion of aggressive EC cells. The indicated EC cell lines or human cervical cancer cell line HeLa were transiently transfected with PD-L1 expression vector (PD-L1-vec) or the control vector (Ctr-vec), and subjected to cell functional assays. Heatmap depicting the fold changes in cell proliferation, apoptosis, migration and invasion of the PD-L1-vec-transfected cells when compared with the Ctr-vec-transfected cells.