Purpose: Degradation of the extracellular matrix by malignant tumor cells has an essential role in the process of tumor invasion and metastasis. The 2 gelatinolytic matrix metalloproteinases (MMPs) MMP-2 and MMP-9 are believed to be key enzymes in this process. We investigated the possible relationship between in situ gelatinolytic activity of MMPs and clinicopathological factors in patients with bladder cancer to clarify whether these proteins would be critical for tumor advancement in this disease.
Materials and Methods: We evaluated the intensity of gelatinolytic activity in 25 bladder cancer tissues by film in situ zymography (FIZ). To clarify the MMP(s) responsible for gelatinolytic activity in bladder cancer tissues we examined MMP-2 and MMP-9 expression in bladder tissues by gelatin zymography. MMP expression was also confirmed by reverse transcriptase-polymerase chain reaction and Western blotting. We then investigated the association between MMP expression detected by gelatin zymography and the intensity of gelatinolytic activity determined by FIZ.
Results: FIZ demonstrated that all tumor tissues had in situ gelatinolytic activities. There was a statistically significant correlation between the intensity of gelatinolytic activity, and tumor grade, stage, vessel invasion and cause specific survival (p < 0.05). Stronger in situ gelatinolytic patterns were documented in cases with higher pro and active MMP-2 expression.
Conclusions: FIZ enables the direct assessment of in situ gelatinolytic activity in bladder cancer tissues. The intensity of activity appears to affect the biology of carcinoma tissues. Our results indicate a major role for MMP-2 in in situ gelatinolysis in bladder cancer.