Increased expression of membrane type 1-matrix metalloproteinase in head and neck carcinoma

BACKGROUND: Three types of membrane type-matrix metalloproteinases (MT-MMPs) have been identified as activators of pro-MMP2 (gelatinase A/72-kilodalton Type IV collagenase), which is believed to be crucial for tumor invasion and metastasis. MT1-MMP has been shown to be widely expressed in various tissues and to be overexpressed in lung and gastric carcinomas. METHODS: Activation of pro-MMP2 was examined in head and neck squamous cell carcinoma (HNSCC) by gelatin zymography. The expression of the MT1-MMP mRNA transcript was studied by Northern hybridization and that of MT1-MMP protein by immunohistochemical staining with a monoclonal antibody against MT1-MMP. RESULTS: Activation of pro-MMP2 was observed in ten of ten HNSCC tissues. Increased expression of the MT1-MMP mRNA transcript was also detected in eight of eight of these tissues. MT1-MMP positive cells were detected at the tumor cell lesions in the majority of these carcinoma tissues by immunohistochemical staining (24 of 27). MT1-MMP expression was more intense in moderately and well differentiated tumors than in poorly differentiated ones (P < 0.05). CONCLUSIONS: These results suggest that MT1-MMP is involved in the activation of pro-MMP2 in HNSCC. These findings suggest that MT1-MMP is significant not only as a tumor marker but as a new target for chemotherapy against HNSCC.