Elevated matrix metalloproteinase-7 expression promotes metastasis in human lung carcinoma

BACKGROUND: Matrix metalloproteinase 7 (MMP-7) promotes tumor invasion and metastasis in several cancers. However, its role in lung cancer progression is understudied. In this study, we investigated the correlation between MMP-7 expression and lung cancer pathology. METHODS: We searched the databases PubMed, Embase, Web of Science, Cochrane Library, CISCOM, CINAHL, China BioMedicine (CBM) and China National Knowledge Infrastructure (CNKI) for scientific literature relevant to MMP-7 and lung cancer. Carefully selected studies were pooled and ORs with 95% CI were calculated. Subgroup analyses and publication bias were analyzed to understand the retrieved data in greater detail. Version 12.0 STATA software was used for statistical analysis. RESULTS: We retrieved a total of 121 studies through database searches. Finally, 14 cohort studies satisfied our inclusion/exclusion criteria, and these 14 studies, published between 2004 and 2012, were selected for meta-analysis to understand the influence of MMP-7 expression in lung cancer progression. Our results showed consistent differences in MMP-7 expression when comparisons were made between TNM I-II versus III-IV (OR = 1.82, 95% CI: 1.19 to 2.78, P = 0.006); histologic grade 1 to 2 versus 3 to 4 (OR = 1.67, 95% CI: 1.14 to 2.42, P = 0.008); and lymph node-negative versus lymph node-positive samples (OR = 2.81, 95% CI: 1.73 to 4.58, P <0.001), with significantly higher MMP-7 expression levels found in the more advanced stages. Subgroup analysis showed that age was not the factor influencing the associations between histologic grade, LN metastasis and MMP-7 expression in lung cancer patients, as both under 60 and over 60 age groups showed strong correlations (all P <0.05). However, when TNM staging was analyzed for its association with MMP-7 expression, only patients under age 60 showed a statistically significant correlation. CONCLUSIONS: Our meta-analysis results revealed that MMP-7 overexpression is associated with advanced TNM and histological grades, and is linked to aggressive LN metastasis in lung cancer patients; thus MMP-7 is a useful biomarker to assess the disease status in lung cancers.