Elevated matrix metalloproteinase-9 expression may contribute to the pathogenesis of bladder cancer

The present study investigated the potential association between matrix metalloproteinase-9 (MMP-9) expression and the pathogenesis of bladder cancer. The present study reviewed previous studies published in Chinese and English using predefined selection criteria, which identified high-quality studies concerning MMP-9 and bladder cancer. Statistical analyses of the data were conducted using Comprehensive Meta-Analysis software version 2.0. In total, 23 case-control studies were selected, which consisted of 1,040 bladder cancer patients and 244 healthy controls. The expression rates and protein levels of MMP-9 were significantly increased in bladder cancer patients compared with the healthy controls, which was demonstrated using immunohistochemistry (IHC) and enzyme-linked immunosorbent assay-based methods. Furthermore, the expression rate of MMP-9 in histological G1/G2 grade bladder cancer tumors was significantly decreased compared with G3 tumors. Subgroup analysis based on ethnicity demonstrated that the rate of MMP-9 protein expression between bladder cancer patients and healthy controls was significantly different in African, Asian and Caucasian patients, which was identified using IHC. The MMP-9 protein levels in bladder cancer patients and healthy controls were significantly different between Asian and Caucasian patients, but not African patients. The differences between MMP-9 expression in ethnic groups were also evident in the expression rate of MMP-9 identified in histological G1/G2 grade tumors in Asian and Caucasian patients compared with G3 grade tumors, which was not evident in African patients. In conclusion, the present meta-analysis results markedly indicate that MMP-9 expression is associated with clinicopathological features of bladder cancer, suggesting that MMP-9 may be a useful biomarker in the diagnosis and clinical management of bladder cancer, and may be a valuable therapeutic target.