Tumor Associated Fibroblasts Promote PD-L1 Expression in Lung Cancer Cells

Background and objective Tumor-associated fibroblasts (TAF) is an important part of TME, which inhibits the function of immune cells. CD8+ T cells play a significant role in tumor immunity. T-cell membrane possesses a distinct type of molecule with a negative regulatory function. Upon interaction with its corresponding ligand [programmed death factor ligand 1 (PD-L1)], programmed death factor 1 (PD-1) is activated and thus inhibits the kinase activity of T cells. This study aims to explore the possible effects of TAF on PD-L1 expression in lung cancer cells. Methods Lung cancer cell lines H1975 and H520 were co-cultured with (experiment) or without TAF (control) via Transwell assay for through 48 hours under the same culture condition. H1975 and H520 cells were counted using a microscope. The protein and mRNA expression levels of PD-L1 were detected by FCM assay and PCR analysis, respectively. Results The numbers of lung cancer cells in 100 μm2 for H1975 and H520 cells are (46±21) and (38±10) in the experiment group, respectively, and (16±5) and (12±5) in the control group, respectively (P<0.05). The expression levels of the PD-L1 protein in H1975 and H520 cells are (20.93%±3.54%) and (19.26%±3.04%) in the experiment group, respectively, and (12.58%±2.52%) and (11.60%±2.65%) in the control group, respectively (P<0.05). The mRNA expression levels in H1975 and H520 cells are (16.45±1.25) and (15.38±2.02) pg/mL in the experiment group, respectively, and (7.78±1.27) and (7.20±1.58) pg/mL (P<0.05) in the control group, respectively (P<0.05). Conclusion TAF promotes the growth and increases the expression of PD-L1 in H1975 and H520 cells.