Protein microarrays have shown that
matrix metalloproteinase-7 is upregulated in
head and neck squamous cell carcinomas, but its role in local tissue invasion is still uncertain. We investigated the expression of active
matrix metalloproteinase-7, using tissue microarray, immunohistochemistry, and western blotting, in oral tissues from 24 patients with buccal
squamous cell carcinoma, and correlated the findings with clinicopathological features. Normal buccal tissue samples from the same patients, obtained at sites at least 1 cm from
tumor tissue, served as normal controls. Total
matrix metalloproteinase-7 was detected on western blots in 9 of 15 (60%)
tumor tissue samples and in 2 of 15 (13%) normal mucosal samples; this difference was significant (P=0.008). Moreover, the active
matrix metalloproteinase-7 was expressed only in eight of the nine (89%)
tumor samples that expressed
matrix metalloproteinase-7, and in none of the normal tissue samples, regardless of the expression status of the pro-
matrix metalloproteinase-7. Immunostaining of
matrix metalloproteinase-7 was observed histologically in both
tumor and nonneoplastic epithelium, but immunostaining of active
matrix metalloproteinase-7 was present only in
tumor nests. Expression of active
matrix metalloproteinase-7 was associated with larger
tumor size (P=0.022) and was significantly higher in buccal
squamous cell carcinoma with adjacent skin or bone invasion (P=0.036). In conclusion, active
matrix metalloproteinase-7 expression was associated with more aggressive buccal
squamous cell carcinomas.