Figure 4.

Cilengitide downregulates the expression of PD-L1 via STAT3 pathway and decreases the expression of PD-L1 in B16 murine melanoma model. (a and b) B16 and A375 cells were treated with blank control, 20 ng/ml IL-6, 5 µg/ml cilengitide, or 20 ng/ml IL-6 plus 5 µg/ml cilengitide for 12 hours. The expressions of STAT3, p-STAT3, and PD-L1 was detected by Western blotting. (c) B16 cells were inoculated subcutaneously into the C57BL/6 mice, and the mice were treated with 50 mg/kg cilengitide for 7 days. Tumor tissues were then isolated and the expression of PD-L1 was detected by Western blotting. (d) The PD-L1 expression of tumor tissues was detected by immunohistochemical staining. Scale bar: 100 µm. Data were represented as mean ± standard deviation. *p < 0.05, **p < 0.01, ***p < 0.001, NS, not significance (Student’s t test). Western blotting was repeated three times.