Expression of metalloproteinases in human prostate carcinoma and their role in invasion and metastasis.

Abstract

Twenty five surgical specimens of malignant human prostate, 3 lymph nodes with metastatic prostate carcinoma, 5 benign prostate hyperplasia (BPH), 11 normal human prostates, as well as 3 human prostate cell lines (DU-145, PC3 and LNCaP) were examined for the expression of human matrix metalloproteinase-7 gene (MMP-7) from the human collagenase family (originally called PUMP-1 for putative metalloproteinase-1) (Majid Siadat-Pajouh et al. 1991). Northern blots were prepared using total RNA extracted from 18 prostate adenocarcinomas, 4 BPH, 2 lymph nodes with metastatic prostate carcinoma and 11 normal human prostates. When the northern blots were hybridized with ³²P labeled MMP-7 cDNA probes, a 1.2 Kb mRNA was detected in 14 out 18 prostate adenocarcinomas, 1 out of 4 BPH, 1 out of 2 metastatic lymph nodes, and 3 out of 11 normal prostates. The 3 human prostate cell lines did not show any evidence of MMP-7 transcript. In situ hybridization was conducted using a ³⁵S labeled MMP-7 cRNA. In situ hybridization was carried out on seven prostate adenocarcinomas, 2 BPH, and 3 metastatic lymph nodes. In situ hybridization revealed that the MMP-7 gene was expressed in the epithelial cells of primary prostate adenocarcinoma as well as invasive and metastatic cells. MMP-7 expression was also seen focally in some benign epithelial cells but not in inflammatory cells or stroma. The combined results of northern analysis and in situ hybridization indicated that 72% of prostate adenocarcinomas, 66% of metastatic prostatic lymph nodes, 40% of BPH and 27% of normal prostate tissues express MMP-7 transcripts. Additional northern blot analysis was performed using probes to human type IV collagenase, type I collagenase and Stromelysin I in human prostate adenocarcinoma as well as normal prostate tissues. The results indicated that 6 out of 10 adenocarcinoma samples and none of the 4 normal samples were positive for type IV collagenase transcripts. None of the tissues examined for the expression of type I collagenase and stromelysin I were found to express the transcripts of interest at detectable levels. A monclonal antibody was generated against a 10 mer synthetic peptide unique to MMP-7. This antibody was reactive with the native protein in frozen prostate tissues. These data suggest that certain metalloproteinases are differentially expressed in prostatic adenocarcinoma and may play a role in invasion and metastasis.