MMP-2 activation and stepwise progression of pulmonary adenocarcinoma: analysis of MMP-2 and MMP-9 with gelatin zymography

Small pulmonary adenocarcinomas can be classified on the basis of their histological characteristics and prognosis, and when classified as such, the prognosis of replacing-type adenocarcinoma with active fibroblast proliferation is significantly worse than adenocarcinoma without fibroblast proliferation. In order to clarify the biological mechanisms of the key to the morphological changes associated with active fibroblast proliferation, we examined the activities of matrix metalloproteinase (MMP)-2 and MMP-9, which are important enzymes in the stromal invasion by cancers. The active MMP-2 and MMP-9 content of 40 pulmonary adenocarcinomas that were less than 20 mm in diameter was measured by the gelatin zymography method. The quantity of active MMP-2 in the pulmonary adenocarcinomas with active fibroblast proliferation was higher than in the pulmonary adenocarcinomas without proliferation (P < 0.001), but there were no correlations between the histological features and the activation of MMP-9. The presence of active fibroblast proliferation in small pulmonary adenocarcinomas suggests that the cancer cells have acquired the ability to invade through the action of active MMP-2, and this is thought to be one of the reasons for the worse prognosis of pulmonary adenocarcinoma with active fibroblast proliferation.