Expression of PD-L1, CTLA-4, and LAG-3 in human thyroid carcinoma
Successful therapy of thyroid carcinoma is still challenged by the aggressiveness and poor prognosis of some types: poorly differentiated thyroid carcinoma and undifferentiated thyroid carcinoma. We investigated the expression of immune checkpoint and ligand proteins in thyroid carcinoma and got some knowledge about the immune microenvironment in thyroid carcinoma. Our research found that programmed death-ligand 1, cytotoxic T-lymphocyte-associated protein 4 and lymphocyte-activation gene 3 proteins were overexpressed in thyroid carcinoma. There was a significant correlation between cytotoxic T-lymphocyte-associated protein 4+ and lymphocyte-activation gene 3+ particles in 74 thyroid carcinoma cases. In addition, the expression rate of programmed death-ligand 1, cytotoxic T-lymphocyte-associated protein 4 and lymphocyte-activation gene 3 in undifferentiated thyroid carcinoma was higher than in differentiated thyroid carcinoma and poorly differentiated thyroid carcinoma. Our results show that the investigated immune checkpoint and ligand proteins are potential targets for aggressive thyroid malignant tumor immunotherapy. Moreover, our data suggest that combination of cytotoxic T-lymphocyte-associated protein 4 and lymphocyte-activation gene 3 immune checkpoint inhibitors might be an attractive treatment strategy for thyroid carcinoma patients with dual positive expression of these proteins. It is important to continue our research on thyroid tumor immunotherapy to validate the optimal immune checkpoint target and thus to find out suitable inhibitors for thyroid carcinoma therapy.