Purpose: Cystic lesions of the kidney are common conditions usually diagnosed by imaging. Although simple cysts are easy to diagnose, preoperative diagnosis of a complicated cystic lesion can be difficult. There is little information available on the biological activity of cystic fluid and associations with clinicopathological findings. We analyzed the expression of matrix metalloproteinase (MMP) in the fluids of benign and malignant renal cystic lesions to clarify matriolytic activities in the cyst.
Materials and methods: Included in this study were 22 samples of cystic fluids from renal cystic lesions, including 14 benign cysts and 8 cystic renal cell carcinomas. MMP-2 and 9 was determined in fluids using gelatin zymography and enzyme-linked immunosorbent assay.
Results: MMP-2 expression was ubiquitously observed on zymography except for 2 benign cysts associated with acquired cystic disease of the kidney. MMP-9 was detected in 7 of 8 carcinomas but in only 2 of 14 benign cysts (p <0.01). The concentration of MMP-2 and 9 was significantly higher in cystic carcinomas than in benign cysts (p <0.01).
Conclusions: Our data show that MMPs were detectable in cystic fluids in the presence of renal cystic changes. MMP-2 and 9 are more abundant in cystic carcinoma fluids than in benign cystic fluids. These observations suggest that matriolytic enzymes in renal cystic fluid reflect biological aggressiveness and in part explain the pathogenesis of renal cystic lesions.