Matrix Metalloproteinase-9 Expression in Lung Cancer Patients and Its Relation to Serum MMP-9 Activity, Pathologic Type, and Prognosis

Background: Matrix metalloproteinase-9 is closely associated with the invasive and metastatic potential of most types of solid cancers. Our objective was to investigate the MMP-9 expression in lung cancer and to evaluate their relations to histopathologic types and prognosis. Methods: Bronchoscopic samples were obtained from tumor and normal bronchial mucosa in 25 patients with lung cancer. Total RNA was isolated from the tissues, and the relative expression as well as the activity of MMP-9 was evaluated. Results: Non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) showed significantly higher MMP-9 expression (P < 0.0001) compared with normal tissues. MMP-9 activity in tissue and serum samples from both cancer groups were significantly higher than normal tissue and serum controls (P < 0.0001). Also, MMP-9 expression and tissue and serum activity were significantly higher in NSCLC than in SCLC (P = 0.0167, 0.0454, and 0.004, respectively). As regards the pathologic types of NSCLC, similar results were found for the adenocarcinoma subgroup versus squamous cell lung cancer (P = 0.0015, 0.0052, and 0.0011, respectively). MMP-9 expression and tissue activity were higher in stage III-IV NSCLC cases compared with early tumor stages (P = 0.0120 and 0.0271, respectively). Conclusions: The expression and activity of MMP-9 are upregulated in NSCLC and are related to the pathologic type and clinical stage of NSCLC. Significantly higher expression and activity of MMP-9 in tumor tissue than in the surrounding tissue supports the important role of this metalloproteinase in the growth of lung cancer, and it could be used as a suggested therapeutic target.