Differential expression of low density lipoprotein receptor–related protein 1 (LRP-1) and matrix metalloproteinase-9 (MMP-9) in prostate gland: From normal to malignant lesions

Abstract

Background Metalloproteinases (MMPs) are relevant modulators of inflammation, tumor microenvironment, cancer invasion and metastasis. They can be regulated by the Low density lipoprotein Receptor?related Protein 1 (LRP-1), a receptor reported to mediate the clearance of lipoproteins, extracellular matrix (ECM) macromolecules and proteinases. The aim of this study was to evaluate the expression of LRP-1, MMP-2 and MMP-9 across various grades of prostatic diseases as benign prostatic hyperplasia (BPH), BPH plus prostatitis (BPH + P), high grade prostatic intraepithelial neoplasia (HGPIN) and prostate cancer (PCa). Methods LRP-1 was analyzed using immunohistochemistry and MMPs proteolytic activity by zymography in prostate tissues with different prostatic diseases. Results LRP-1 was detected in epithelial cells in BPH (16/18), BPH + P (21/21) and HGPIN (6/6), with a staining intensity of 1+, 1+/2+ and 3+, respectively. In PCa, LRP-1 was absent in 19/27 samples while a low expression was observed in 8/27 biopsies. MMP-9 activity was higher and statistically significant in PCa than in BPH (p ≤ 0.01). Conclusion Considering that LRP-1, by mediating the clearance of MMPs, is involved in the regulation of ECM remodeling and cell migration, we conclude that a decreased expression of LRP-1 could be involved with the increasing activity of MMPs shown in cancers.