Abstract
Esophageal squamous cell carcinoma (ESCC) is an aggressive tumor, and it is urgently needed to develop novel therapeutic strategies including immunotherapy. In this study, we investigated the upregulation of the programmed death ligand 1 (PD‐L1) due to epithelial‐mesenchymal transition (EMT) in ESCC using an in vitro treatment system with the EMT inducer, glycogen synthase kinase (GSK)‐3 inhibitor, and we also analyzed the correlation of EMT and PD‐L1 expression in the clinical tumor samples of both tissue microarray (TMA) samples (n = 177) and whole tissue samples (n = 21). As a result, the inhibition of GSK‐3β induces EMT phenotype with upregulated vimentin and downregulated E‐cadherin as well as increased Snail and Zinc finger E box‐binding homeobox (ZEB)‐1 gene expression. Simultaneously, we showed that EMT‐converted ESCC indicated the upregulation of PD‐L1 at both protein (total and surface) and mRNA levels. Of importance, we showed that EMT‐converted tumor cells have a capability to induce T‐cell apoptosis to a greater extent in comparison to original epithelial type tumor cells. Furthermore, the immunohistochemical stains of ESCC showed that PD‐L1 expression on tumor cells was positively correlated with EMT status in TMA samples (P = .0004) and whole tissue samples (P = .0029). In conclusion, our in vitro and in vivo study clearly demonstrated that PD‐L1 expression was upregulated in mesenchymal type tumors of ESCC. These findings provide a strong rationale for the clinical use of anti‐PD‐1/anti‐PD‐L1 monoclonal antibodies for advanced ESCC patients.
Highlights
Esophageal cancer affects more than 450 000 people, and the incidence is increasing worldwide now.[1]
The programmed death ligand 1 (PD-L1) expressed on tumor cells binds to PD-1 on tumor infiltrating lymphocytes (TILs) in tumor microenvironments, allowing tumor cells to escape from immune attack with TILs and leading TILs to apoptosis.[10,11,12]
We evaluated the correlation of epithelial-mesenchymal transition (EMT) status with PD-L 1 expression in esophageal squamous cell carcinoma (ESCC) samples, using 2 independent cohorts of tissue microarray (TMA) and whole tissues sections obtained from a total of 198 patients with ESCC who underwent surgery
Summary
Esophageal cancer affects more than 450 000 people, and the incidence is increasing worldwide now.[1]. One hundred and seventy-seven TMA samples (3 cores each from 177 tumors) of patients with ESCC, who underwent esophagectomy between January 2000 and December 2011, were provided from Department of Thoracic Surgery, Akita University Graduate School of Medicine.[30] We obtained 21 formalin-f ixed paraffin embedded (FFPE) whole tissue samples of ESCC, which were surgically resected at FIGURE 1 Treatment with GSK-3 inhibitor induces epithelial-mesenchymal transition in KYSE30, esophageal squamous cell carcinoma cell line. For E-c adherin staining, antigens on the samples were retrieved using autoclaving for 5 minutes in 10 mmol/L citrate buffer solution (105°C, pH 6.0), and the samples were incubated with the primary mouse monoclonal antibody for E-cadherin (1:200, NCH-38, Dako) at 4°C overnight and detected a horseradish peroxidase (HRP)-coupled anti- mouse polymer (Envision+System-HRP, Dako, Belgium) followed by incubation with diaminobenzidine (DAB, Dojindo, Maryland). The standard mean error (SEM) was calculated and used as the error bar
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
