Toll-like receptor 5 and 7 expression in adenoid cystic carcinoma of major salivary glands

Adenoid cystic carcinoma (ACC) of the salivary glands has a poor long-term prognosis and high metastatic rate. Toll-like receptors (TLRs) have been related to tumour progression but have also tumour growth-inhibiting responses. To the best of our knowledge, they have not been studied previously in ACC. We studied the immunoexpression of TLR 5 and 7 in ACC of the major salivary glands. From a cohort of 54 patients with ACC of the major salivary glands treated at the Department of Otorhinolaryngology-Head and Neck Surgery, Helsinki University Hospital, Helsinki, Finland in 1974-2009, there were 34 primary tumours and six metastases available for immunohistochemical analysis. Immunohistochemical expression of TLR 5 and 7 were correlated to clinicopathological findings and patient survival. Both TLR 5 and 7 were expressed in ACCs and their metastases, mostly on the cell membranes. The expression was heterogeneous in individual tumours. TLR 5 was expressed less in male samples, and TLR 7 had lower expression in ACCs with solid growth pattern. No correlation with survival was found. In the normal salivary gland, the TLR 5 and 7 expression was mainly negative. Both TLR 5 and 7 are expressed in salivary adenoid cystic carcinoma on the cell membranes as well as in cytoplasm.