Tumor-Associated Macrophages in the Development of 4-Nitroquinoline-1-Oxide-Induced Tongue Squamous Cell Carcinoma in a Mouse Model

Objective: We aimed to determine the distribution of tumor-associated macrophages (TAMs) in the development of tongue squamous cell carcinoma (SCC) and to elucidate the role of TAMs in the progression of tongue SCC. Methods: The expression of the macrophage markers nitric oxide synthase, Retnla, and mannose receptor 1 in the development of tongue SCC was longitudinally observed using real-time quantitative polymerase chain reaction. Additionally, an immunohistochemical study using an anti-mannose receptor (MR) antibody was performed. Results: The numbers of both of M1 and M2 macrophages in the tongues of mice treated with 4-nitroquinoline-1-oxide (4NQO) were significantly lower compared with those of normal tongues. The cyclooxygenase-2 (COX-2) inhibitor did not prevent cancer progression and did not affect the total number of macrophages in the tongues of 4NQO-treated mice. In the immunohistochemical studies, MR staining was observed in lymphangioendothelium in the subepithelial area of the tongues. The staining intensity of the MR was significantly stronger in the 4NQO-treated mice compared with that in control mice and 4NQO-treated mice treated with the COX-2 inhibitor. Conclusion: TAMs may not contribute to the development of 4NQO-induced tongue SCC. MR expression is associated with the progression of 4NQO-induced tongue SCC.