Fig. 5

Role of cyclooxygenase 2 (COX-2) and prostaglandin E2 (PGE₂) in the relationship between PD-L1 and Chk-α. a Changes of COX-2 mRNA expression levels, b protein levels, and c PGE₂ production in the supernatant of MDA-MB-231 cells with different siRNA treatments. d Changes of Chk-α and PD-L1 mRNA expression levels at 48 h and e Chk-α and PD-L1 protein levels at 48 h of MDA-MB-231 cells with constitutive low expression of COX-2 (shCOX2-MDA-MB-231) with different siRNA treatments. siRNA treatments: untreated, transfected with 100 nM scrambled siRNA, transfected with 100 nM Chk-α siRNA, transfected with 100 nM PD-L1 siRNA #1, and transfected with a mixture of 50 nM PD-L1 #1 and 50 nM Chk-α siRNA. Data in a and d are presented as box and whisker plots, with the middle line representing the mean and the whiskers representing the maximum to minimum data points from 4 independent experiments. Values in c represent the mean ± SEM from 4 independent experiments. Statistical significance was calculated from ΔCt values. *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, compared to untreated cells. ⁺p ≤ 0.05, ⁺⁺p ≤ 0.01, ⁺⁺⁺p ≤ 0.001, compared to cells transfected with scrambled siRNA