The matrix metalloproteinase system in oral squamous cell carcinoma.

Background: The matrix metalloproteinase (MMP) system is responsible for degradation of tissue in both normal and pathological processes, including tumour invasion and metastasis.

Aim: To compare tissue concentrations of components of the MMP system between tumour tissue and normal tissue in patients with oral squamous cell carcinoma, and to correlate concentrations with pathological grade of tumour.

Methods: Thirty-eight paired tissue samples from tumours and normal tissue were analysed by three laboratory techniques: firstly, enzyme linked immunosorbent assays (ELISA) in ng/mg protein for MMP-1, MMP-3, and tissue inhibitors of metalloproteinases (TIMPs) -1 and -2. Secondly, gelatinase activity assays to measure concentrations of total and endogenous active gelatinases, MMP-2 and MMP-9 (ng/mg protein). And thirdly to use quenched fluorescent substrate hydrolysis to measure total MMP activity (pM/min).

Results: The concentration of all MMPs was significantly higher in tumour than in normal oral tissue (p < 0.05, Mann-Whitney U-test). Tissue concentrations of some of these factors correlated with clinical and pathological indices of aggressiveness of tumours, including T-stage, N-stage, tumour differentiation, and anatomical level of involved nodes. However, the study was not powered to show statistical significance.

Conclusion: It is the balance between proteinases and their inhibitors that controls tissue degradation at each stage of tumour invasion and metastasis. Measurement of MMPs in oral mucosal biopsy samples may establish the invasive potential of tumours at their initial presentation.