In situ gene expression and localization of metalloproteinases MMP1, MMP2, MMP3, MMP9, and their inhibitors TIMP1 and TIMP2 in human renal cell carcinoma

Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) play a major role in the maintenance of extracellular matrix homeostasis. Alterations of MMP and TIMP expressions have been found in several malignant tumour entities. In this study the expression pattern of MMP1, MMP2, MMP3, MMP9, and their inhibitors TIMP1, and TIMP2 were investigated at mRNA and protein levels in human renal cell carcinoma (RCC). Formalin fixed paraffin embedded tumour samples of 10 patients and adjacent non-malignant controls were analysed by radioactive labelled riboprobe in situ hybridisation (isH) and immunohistochemistry. The slides were evaluated semiquantitatively. MMP1-antigen was strongly expressed in tumour epithelium with moderate stroma expression in one case. The gelatinases MMP2 and MMP9 showed moderate to strong signals in tumour epithelial cells at the mRNA and protein level, while the expression in tumour stroma was moderate. MMP3-mRNA and -antigen were expressed moderately to strong in tumour epithelium and focally in stroma cells. mRNA or TIMP1- and TIMP2-mRNA and -antigen were also predominantly expressed in tumour epithelium; only few samples showed positive expression in stroma cells. mRNA expression could be generally correlated to the protein expression in our study group, except for MMP1 (mRNA expression was only expressed in two cases). We found a pronounced expression for the gelatinases MMP2 and MMP9 and for MMP3 in RCC at the mRNA and protein level. The expression of TIMP1 and TIMP2 appears also to be relevant in RCC. Due to the small sample size further investigations need to be done to prove a statistical significant correlation between the MMP/TIMP expression and clinicopathological parameters.