Comparison of MMP2 and MMP9 expression levels between primary and metastatic regions of oral squamous cell carcinoma

Matrix metalloproteinases (MMPs) and tumor-associated macrophages (TAMs) play important roles in tumor growth. The present study investigated the expression levels of MMP2 and MMP9 in relation to the distribution of TAMs in the primary and metastatic regions of oral squamous cell carcinoma. Twenty-nine cases of oral squamous cell carcinoma (OSCC) with regional lymph node metastasis were selected from available documents in the archives of the Department of Pathology, Nihon University School of Dentistry. Four-micrometer thick sections were prepared from the primary and metastatic regions. Each section was subjected to immunohistochemical staining using anti-MMP2, anti-MMP9, and anti-CD68 antibodies. The distribution and localization of MMPs and TAMs were compared between primary and metastatic regions. The expression levels of both MMPs were higher in the metastatic regions of lingual and gingival cancers. Statistically significant differences were observed in both T1 and T2 cases. In contrast to the higher expression of MMPs in metastatic regions, a higher number of TAMs were distributed in the primary regions. From these results, MMP expression levels and the numbers of TAMs were expected to have an inverse relationship between the primary and metastatic regions of OSCC.