Relationship between IL-10 and PD-L1 in esophageal carcinoma tissues and IL-10 down-regulates PD-L1 expression via Met signaling pathway

Background: Programmed death-ligand 1 (PD-L1) plays a critical role in host immunity in the setting of cancer progression. Interleukin 10 (IL-10) is a multi-cellular, multi-functional cytokine that regulates cell growth and differentiation and participates in inflammatory and immune responses. The purpose of this study was to clarify the relationship between PD-L1 and IL-10 and their clinical importance in esophageal carcinoma (ESCA). Methods: ESCA patients (n=100) who underwent surgery with preoperative therapy were included in the study. By immuno-histochemical staining, PD-L1, IL-10 and CD8 positive cells were examined in resected specimens. The gene expression levels of PD-L1, IL-10 and Met were detected by qRT-PCR and Western blots, and differentially compared in cancer, adjacent and normal tissues. In cell experiments, the Eca109 and TE-1 cell-lines were incubated with IL-10 or anti-IL-10 antibody, and then PD-L1 and Met expression levels were compared by ELISA and Western blots. The effect of crizotinib and/or IL-10 on the proliferation, invasion and migration of esophageal squamous cell-lines was estimated by CCK8 and transwell assay. Results: In tumor tissues, the mRNA and protein levels of PD-L1, IL-10 and Met were higher than those in adjacent tissues. The high expression levels of PD-L1 and IL-10 indicated a poor prognosis. IL-10 reduced the expression of PD-L1 in esophageal squamous cell-lines via Met signaling. Over-expression of PD-L1 in increased the levels of IL-10, and Met in in ESCA tissue and cell lines. The combination of crizotinib and IL-10 were more effective in inhibiting the proliferation, migration and invasion of esophageal squamous cell lines. Conclusions: The combination of IL-10 and PD-L1 monoclonal antibody may have therapeutic promise in treating ESCA.