Fig. 7

IL-6 regulated tumor PD-L1 expression via the IL-6/STAT3 pathway. A Western blot analysis of p-STAT3, STAT3 and PD-L1 in A549 cells serum-starved for 12 h and then treated with IL-6, IL-6 and tocilizumab, IL-6 and S3I-201 (a STAT3 inhibitor). β-actin was used as the equal loading control. B Western blot analysis of p-STAT3, STAT3 and PD-L1 in A549 cells serum-starved for 12 h and then treated with MPE, MPE and tocilizumab, MPE and S3I-201. β-actin was used as the equal loading control. C Quantification of PD-L1 expression in tumor cells (CD45⁻CD90⁻) in MPE mice tumor nodules by MFI analysis through flow cytometry. D Western blot analysis of PD-L1 in mice tumor nodules. β-actin was used as the equal loading control. E Representative images of IHC staining of IL-6 and p-STAT3 in the MPE mice tumor nodules. Scale bar = 100 µm. F Schematic representation of the co-culture system of CAFs and A549. A549 was serum-starved for 12 h and then co-cultured with CAFs and tocilizumab. G Western blot analysis of p-STAT3, STAT3, and PD-L1 in A549 cells co-cultured with CAFs and treated with tocilizumab. β-actin was used as the equal loading control. All experiments were performed with ≥ 3 biological replicates. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001, ns: not statistically significant. MFI, mean fluorescence intensity; tPD-L1, tumor PD-L1; CAFp1, CAFs isolated from patient 1; CAFp2, CAFs isolated from patient 2; TCZ, tocilizumab