LOCATION OF 72-KD METALLOPROTEINASE (TYPE-IV COLLAGENASE) IN UNTREATED PROSTATIC ADENOCARCINOMA

The aim of the study was to investigate the location of the expression of 72-kd metalloproteinase (MMP-2) in relation to the distribution of type IV collagen in untreated prostatic adenocarcinoma (PAc). Twenty formalin-fixed, paraffin-embedded PAc cases, in which high grade prost atic intraepithelial neoplasia (PINhigh) was occasionally present, wer e immunohistochemically examined. Type IV collagen immunoreactivity sh owed the presence of a basement membrane (BM) at the epithelial-stroma l junction. In cribriform and solid/trabecular PAc, the staining was f ocally disrupted. In acinar PAc, the BM immunostained by anti-type IV collagen was observed around the individual acini, with occasional thi nning and fragmentation. Immunostaining for MMP-2 was heterogeneous in intensity and location. Cribriform and solid/trabecular PAc showed we ak cytoplasmic immunostaining for MMP-2; both moderately and intensely stained cells were seen in the cell layer adjacent to the stroma; int ense immunostaining was shown by small clusters of neoplastic cells or single neoplastic cells located in the stroma which also showed thinn ing and fragmentation of BM staining. In acinar PAc, weak cytoplasmic immunostaining for MMP-2 was seen throughout most areas of the tumours , whereas moderately and intensely stained cells were observed less fr equently than in cribriform and solid/trabecular adenocarcinoma. Inten se immunostaining of single or small clusters of neoplastic cells loca ted in the stroma was rarely observed and, as for cribriform and solid /trabecular PAc, mainly located towards the periphery of the tumour no dules. BM stained by anti-type IV collagen was preserved in normal pro state and in PIN, some thinning being present in the latter. The patte rn and intensity of immunoreactivity for MMP-2 in PIN was similar to t hat of cribriform and solid-trabecular PAc, whereas normal ducts and a cini showed weak immunostaining in most of the secretory cells and mod erate to strong immunoreactivity in scattered basal cells. Thus, MMP-2 appeared basically expressed in cells which lie in direct contact wit h the stroma. This underlined the importance of evaluating the MMp-2 l ocation in relation to basement membrane degradation and tumour invasi on.