Elevated expression of matrix metalloproteinase-9 is associated with bladder cancer pathogenesis

This study investigated the association between abnormal matrix metalloproteinase-9 (MMP-9) expression and bladder cancer (BC) development.

In a retrospective analysis, this study used tissue samples derived from 92 patients pathologically diagnosed with BC (experimental group), who were hospitalized between September 2012 and June 2014 at the Urinary Surgery of Department of Urology, Lanzhou University Second Hospital. As controls (control group), 63 normal pericancerous bladder mucosal tissues (3 cm distant form edge of BC foci) with confirmed pathology were selected from the same time period. Immunohistochemistry was employed to detect MMP-9 protein expression in the tissues and enzyme-linked immunosorbent assay was performed to measure MMP-9 protein levels in tissue samples of patients and control subjects. Finally, a meta-analysis was conducted to understand the overall impact of MMP-9 on BC pathogenesis. STATA 12.0 software (Stata Corp, College Station, TX, USA) was used for all statistical analyses.

The MMP-9 positive expression rate in tissue samples and MMP-9 levels were significantly greater in the experimental group compared to the control group (both P < 0.001). The frequency of MMP-9 positive status showed statistically significant differences between G1 (low-grade) and G3 (high-grade) (P < 0.001), between G2 and G3 (P < 0.05), and between G1/G2 and G3 (P = 0.001). Our meta-analysis findings provided further evidence that MMP-9 positive expression status and MMP-9 levels in the experimental group were significantly higher than the control group (positive expressions: Odds ratio [OR] = 18.59, 95% confidence interval [95% CI] = 11.63-29.71, P < 0.001; expression levels: Standard mean difference = 1.51, 95%CI = 0.63-2.39, P = 0.001). The positive expression status of MMP-9 was notably lower in G1/G2 compared to G3 (OR = 0.24, 95%CI = 0.15-0.36, P < 0.001).

Our study demonstrated that both positive expression status in tumor tissue and expression levels of MMP-9 are significantly elevated in BC patients and correlate with disease progression. Thus, MMP-9 can serve as a biomarker to determine the degree of BC malignancy.