Clinical Significance and Prognostic Value of the Expression of LAG-3 and FGL1 in Esophageal Squamous Cell Carcinoma.

In this retrospective study, we analyzed the expression of lymphocyte activating gene 3 (LAG-3) and fibrinogen-like protein 1 (FGP1) mRNA and the corresponding proteins in 78 patients with esophageal squamous cell carcinoma (ESCC) to evaluate the clinical significance and prognostic value. mRNA and protein expression were analyzed by reverse transcription PCR and Western blotting, respectively. The expression of LAG-3 and FGL1 mRNA and the corresponding proteins in tumor tissues were significantly increased in comparison with the normal esophageal mucosa. The overexpression of LAG-3 significantly correlated with the content of tumor-infiltrating lymphocytes (TILs), tumor differentiation, and TNM stage. The overexpression of FGL1 also significantly correlated with TILs, TNM stage, and lymph node metastasis. Kaplan-Meier survival analysis showed that tumor diameter, TNM stage, lymph node metastasis, LAG-3 and FGL1 protein expression were related to the progression-free survival (p<0.05). Multivariate Cox regression showed that the level of FGL1 and TNM stage were independent prognostic factors of progression-free survival. We speculated that the tumor microenvironment of ESCC induces immunosuppression due to up-regulated expression of LAG-3 and FGL1 in the tumor tissues, which promotes tumor growth.