Overexpression of LAG3, TIM3, and A2aR in adenoid cystic carcinoma and mucoepidermoid carcinoma.

OBJECTIVE: Adenoid cystic carcinoma (AdCC) and mucoepidermoid carcinoma (MEC) are the two most frequent malignancies of salivary glands. This study aims to explore the expression and migration of LAG3, TIM3, and A2aR in AdCC and MEC, and the potential relationship with oncogenic signaling molecules and immunosuppressive cytokines. MATERIALS AND METHODS: Custom made human salivary gland tissue microarrays included 81 AdCCs, 52 MECs, 76 normal salivary glands (NSG), and 14 pleomorphic adenoma (PMA) samples. Immunohistochemical analysis of lymphocyte activation gene 3 (LAG3), T-cell immunoglobulin and mucin domain-containing protein 3 (TIM3), adenosine 2a receptor (A2aR), oncogenic phosphorylated S6 kinase (p-S6) and ERK(1/2) (p-ERK(1/2) ), and TGF-beta1 was performed with salivary gland tissue microarrays of human samples. The correlation of the immunostaining was analyzed based on a digital pathological system, and data were evaluated by hierarchical cluster. Further in vitro studies of knockdown immune checkpoints LAG3, TIM3, and A2aR were carried out by siRNA transfection. RESULTS: The expression levels of LAG3, TIM3, and A2aR were remarkably increased in AdCC and MEC, compared with NSG and PMA samples, but were independent of pathology grade. They were closely correlated with TGF-beta1, slightly related to p-ERK(1/2) and p-S6. After the knockdown of immune checkpoints LAG3, TIM3, and A2aR, the migration of SACC-LM cell line was significantly reduced. CONCLUSIONS: These results suggested that LAG3, TIM3, and A2aR are overexpressed in AdCC and MEC, may promote migration of SACC-LM cell and correlated with TGF-beta1 and oncogenic signaling pathways.