Fig. 5

THZ1 downregulates PD-L1 expression by inhibiting MYC signaling. a Quantitation of relative PD-L1 mRNA expression in NSCLC cell lines transfected with either scramble or CDK7 siRNAs. Results are normalized to GAPDH (n = 3) (***P < 0.001 as compared to scramble group). b Changes of PD-L1 protein level in A549 cells transfected with either CDK7 siRNAs (compared to scramble group) or treated with THZ1 for 48 h (compared to vehicle group). GAPDH was used as a loading control. c Immunoblot of MYC and PD-L1 proteins after A549 cells transfected with CDK7 siRNAs, MYC vector, or the combination. GAPDH was used as a loading control. d Quantitation of relative PD-L1 mRNA level in A549 cells transfected with CDK7 siRNAs, MYC vector, or the combination. GAPDH was used as a loading control. e Representative images and quantitation of PD-L1 level on surfaces of NSCLC cell lines treated with THZ1 (200 nM) at 24 h (n = 3) (*P < 0.05; ***P < 0.001). f Representative images and quantitation of PD-L1 level on surfaces of NSCLC cell lines transfected with either scramble or CDK7 siRNAs (n = 3) (***P < 0.001 as compared to scramble group). g NSCLC cells were pretreated with vehicle or THZ1 (200 nM) and then cocultured with PBMC (1:10) for 3 days. Left y-axis indicates log 2 of fold change in cell number at 3 days relative to day 0 (n = 3) (***P < 0.001). h Correlation between PD-L1 protein level and CDK7 protein level in cohort I and cohort II tumor samples. i Patients with CDK7 and MYC double high levels had a higher PD-L1 score than patients with CDK7 and MYC double low based on cohort I data (*P < 0.05) and cohort II data (***P < 0.001)