Purpose: Although an important risk factor for oral cancer is the presence of epithelial dysplasia, many lesions will not progress to malignancy. Matrix metalloproteinases (MMPs) are zinc-dependent proteinases capable of digesting various structural components of the extracellular matrix. Because MMPs are frequently overexpressed in oral squamous cell carcinoma (SCC), we hypothesized that they are also overexpressed in oral dysplasias; we also hypothesized that those dysplasias that progress to oral cancer express higher levels of MMPs than those lesions that do not progress.
Experimental design: In this retrospective study, we examined changes in MMP-1, -2, and -9 mRNA expression using quantitative TaqMan reverse transcription-polymerase chain reaction in 34 routinely processed oral dysplasias and 15 SCCs obtained from 34 patients. After several years of close follow-up, 19 dysplasias progressed to oral SCC and 15 did not.
Results: Overall, MMP-1 mRNA was overexpressed (>2-fold) in 24 of 34 (71%) dysplasias and 13 of 15 (87%) oral SCCs. MMP-2 overexpression was seen in 11 of 34 (32%) dysplasias and 7 of 15 (47%) cancers; for MMP-9, overexpression was identified in 29 of 34 (85%) dysplasias and 15 of 15 (100%) cancers. MMP-1 and -9 levels were significantly higher in the SCCs compared with all oral dysplasias (P = 0.004 and P = 0.01, respectively). MMP-1 and -9 mRNA levels were significantly higher in the oral dysplasias that progressed to oral cancer compared with those that did not (P = 0.04 and P = 0.002, respectively).
Conclusions: Levels of MMP-1 and -9 mRNA may be markers of malignant transformation of oral dysplasia to oral cancer.