Metalloproteinase-2 expression correlates with aggressiveness of cutaneous squamous cell carcinomas

Matrix metalloproteinases compose a family of enzymes involved in degradation of the extracellular matrix. Tumor cells must penetrate the basement membrane and traverse the extracellular matrix in order to invade surrounding structures and metastasize to distant sites. Gelatinases, particularly gelatinase A (matrix metalloproteinase-2), demonstrate degradative activity against components of the basement membrane and may be involved in the progression of in situ squamous cell carcinoma lesions. Matrix metalloproteinase-2 overexpression has been correlated with tumor invasiveness and metastasis in a wide variety of cancer types, including squamous cell carcinoma arising on mucous membranes. However, correlation between matrix metalloproteinase-2 overexpression and the spread and prognosis of cutaneous squamous cell carcinoma has not been characterized in the literature at present. In this study, we used immunohistochemical techniques to examine the expression of matrix metalloproteinase-2 in 10 actinic keratosis, 15 in situ, 13 invasive, 13 primary (with documented metastatic disease), 11 metastatic, and 8 recurrent squamous cell carcinoma cases. We found that while the average staining intensity (scale 0-3+, 3+ being strongest) of actinic keratosis and in situ lesions was not statistically significant (0.87-1.3 and 0.75-1.4, respectively), the average staining intensity of invasive squamous cell carcinomas (1.6-2.5) was significantly greater than that of actinic keratosis and in situ lesions. Likewise, while the average staining intensity of primary squamous cell carcinomas and metastatic squamous cell carcinomas was not found to be statistically significant (3.1-3.5 and 3.1-3.8, respectively), the average staining intensity of these lesions was significantly higher than that of invasive lesions. We also found that the intensity of matrix metalloproteinase-2 staining correlates with cellular atypia, inflammation, neovascularization, and the invasive tumor front, as well as tumor aggressiveness, and may play a role in the pathogenesis, invasion, and metastasis of cutaneous squamous cell carcinoma.