Characterization of TIM-3 Expression and Its Correlation with TNF-α and IFN-γ in Patients with Surgically Resected Lung Adenocarcinoma

OBJECTIVE: T cell immunoglobulin and mucin-containing protein-3 (TIM-3) is an important immune checkpoint, but its role in lung cancer is still not clear. In this study, we investigated TIM-3 protein expression and its correlation with TNF-α and IFN-γ by examining the tissues of patients with lung adenocarcinoma. METHODS: We detected the mRNA quantity of TIM-3, TNF-α, and IFN-γ in 40 surgically resected specimens from patients with lung adenocarcinoma by real-time quantitative polymerase chain reaction (qRT-PCR). The protein expression of TIM-3, TNF-α, and IFN-γ was assessed in normal tissues, paracarcinoma tissues, and tumor tissues by western blotting, respectively. The relevance between the expression and clinicopathological information of the patients was analyzed. RESULTS: The results showed that the expression level of TIM-3 was higher in tumor tissues than normal tissues and paracancerous tissues (P < 0.05). On the contrary, the expression of TNF-α and IFN-γ in tumor tissues was lower than normal tissues and paracarcinoma tissues (P < 0.05). However, the expression levels of IFN-γ mRNA were not observed to be significantly different between cancerous tissues and adjacent tissues. While TIM-3 protein expression in cancer tissues of patients with lymph node metastasis was higher than in patients without metastasis, the expression of TNF-α and IFN-γ was lower (P < 0.05). Importantly, the expression of TIM-3 was negatively correlated with the expression of TNF-α and IFN-γ, and the expression of TNF-α was found to be positively correlated with IFN-γ in the patient. CONCLUSION: The high expression of TIM-3, the low expression of TNF-α and IFN-γ, and the synergistic effect of TNF-α and IFN-γ in patients with lung adenocarcinoma were closely related to poor clinicopathological characteristics. Overexpression of TIM-3 may play an important role in the relationship between TNF-α and IFN-γ secretion and poor clinicopathological characteristics.