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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.

The 72 kDa matrix metalloproteinase (MMP-2) and the 92 kDa matrix metalloproteinase (MMP-9), are type IV collagenases that have been implicated as important factors in cancer invasion and metastasis formation. We have used quantitative zymography and computer-assisted image analysis to measure the levels of MMP-9 and MMP-2 in 19 samples of serum of lung cancer patients and in 23 samples of normal serum. Mean levels of MMP-9 were significantly elevated in cancer samples compared with normal sera (1.33 +/- 0.61 microU microl(-1) vs. 0.37 +/- 0.10 microU microl(-1), P<0.0001). MMP-2 levels did not differ significantly in these two groups. However, there was no significant correlation between serum MMP-9 activity and the disease stage. We found that circulation levels of MMP-9 in lung cancer patients is 3.6-fold higher than in healthy volunteers, however, we do not consider this elevation to be a direct reflection of MMP-9 over-production by tumour cells.