Activity of type IV collagenases (MMP-2 and MMP-9) in primary pulmonary carcinomas: a quantitative analysis

Purpose: Matrix metalloproteinases MMP-2 and MMP-9 are implicated in invasion and metastasis of malignant tumors. We investigated the expression and activation of MMP-2 and MMP-9 in lung cancer compared with normal lung parenchyma, and looked for a potential marker of malignancy. Methods: Thirty-six pulmonary carcinomas and paired normal lung specimens were analyzed by gelatin zymography and computer-assisted image analysis for the expression of MMP-2 and MMP-9. Results: We showed that expression of both type IV collagenases was remarkably higher in carcinoma samples than in lung parenchyma. The MMP-9 levels in lung cancer were over twofold higher than in normal lung tissues. The levels of latent and active forms of MMP-2 in lung cancer samples were, correspondingly, 3.8- and 17-fold higher than in lung parenchyma. The tumor/normal (T/N) ratios of MMP-2 were negatively correlated with the hemoglobin levels and erythrocytes number. Conclusions: A high level of the active form of MMP-2 in almost all of the carcinomas and the near lack of its activation in normal lung parenchyma shows that MMP-2 activation is associated with the malignant phenotype and may serve as a good marker of malignancy. The correlation between low hemoglobin level and T/N ratio of MMP-2 may indicate significance of MMP-2 for angiogenesis.