Immunohistochemical analysis of type IV collagenase expression in prostatic hyperplasia and adenocarcinoma.

The 72-kDa Type IV collagenase (T4C) is a matrix metalloproteinase, the expression of which may be important in normal basement membrane metabolism. The production of T4C by malignant cells has been linked to their invasive and metastatic potential in several tumor systems. The pattern of T4C immunoreactivity was assessed in formalin-fixed, paraffin-embedded prostatic tissue using polyclonal, monospecific antibodies. Basal cells in normal and hyperplastic epithelium demonstrated slight to moderate cytoplasmic immunoreactivity, while secretory epithelial cells showed generally weaker immunostaining. In 35 of 35 cases of primary adenocarcinoma and five of five cases of metastatic adenocarcinoma in lymph nodes, the majority of malignant cells showed strong immunoreactivity. Similar strong immunostaining was also seen in foci of prostatic intraepithelial neoplasia. The high level of expression of T4C in prostatic adenocarcinoma and its metastases suggests this metalloproteinase may play a role in determining the invasive and metastatic properties of this tumor. The enhanced immunoreactivity in prostatic intraepithelial neoplasia suggests the induction of T4C may be an early event in the development of the invasive phenotype. The expression of T4C in benign epithelial cells may be a manifestation of its putative physiological role in basement membrane metabolism.