Matrilysin/matrix metalloproteinase-7(MMP7) cleavage of perlecan/HSPG2 creates a molecular switch to alter prostate cancer cell behavior

Abstract

Perlecan/HSPG2, a large heparan sulfate (HS) proteoglycan, normally is expressed in the basement membrane (BM) underlying epithelial and endothelial cells. During prostate cancer (PCa) cell invasion, a variety of proteolytic enzymes are expressed that digest BM components including perlecan. An enzyme upregulated in invasive PCa cells, matrilysin/matrix metalloproteinase-7 (MMP-7), was examined as a candidate for perlecan proteolysis both in silico and in vitro. Purified perlecan showed high sensitivity to MMP-7 digestion even when fully decorated with HS or when presented in native context connected with other BM proteins. In both conditions, MMP-7 produced discrete perlecan fragments corresponding to an origin in immunoglobulin (Ig) repeat region domain IV. While not predicted by in silico analysis, MMP-7 cleaved every subpart of recombinantly generated perlecan domain IV. Other enzymes relevant to PCa that were tested had limited ability to cleave perlecan including prostate specific antigen, hepsin, or fibroblast activation protein α. A long C-terminal portion of perlecan domain IV, Dm IV-3, induced a strong clustering phenotype in the metastatic PCa cell lines, PC-3 and C4-2. MMP-7 digestion of Dm IV-3 reverses the clustering effect into one favoring cell dispersion. In a C4-2 Transwell® invasion assay, perlecan-rich human BM extract that was pre-digested with MMP-7 showed loss of barrier function and permitted a greater level of cell penetration than untreated BM extract. We conclude that enzymatic processing of perlecan in the BM or territorial matrix by MMP-7 as occurs in the invasive tumor microenvironment acts as a molecular switch to alter PCa cell behavior and favor cell dispersion and invasiveness.

Fibrogenic Lung Injury Induces Non–Cell-Autonomous Fibroblast Invasion

“…Many of these processes appear to be excessive in IPF, however, including fibroblast invasion. The acquisition by cells of the ability to invade across tissue boundaries has been extensively studied in cancer (22)(23)(24)(25), in which cell invasiveness is a hallmark of the metastatic process. The increased ability of fibroblasts to invade through extracellular matrix in IPF has recently been recognized as well.…”

Heralding a new paradigm in 3D tumor modeling

“…Accompanying the deposition of collagen is an increase in lysyl oxidase activity, which crosslinks these fibers, thereby stiffening the ECM and enhancing focal adhesion assembly and signaling [32]. Moreover, tumor cells and myofibroblasts also secrete MMPs that not only degrade ECM to nullify its function as a physical barrier, but also generate ECM fragments that activate latent secreted growth factors that promote tumor survival and invasion [32, 33]. …”

“…Moving forward, with such tunable synthetic 3D systems available for modification, future studies would greatly benefit from mining other ECM-derived motifs to expand our knowledge of the impact of various ECM components on tumor progression and to modulate tumor behavior. As an example, we recently showed that enzymatic cleavage of perlecan (a large heparan sulfate proteoglycan that organizes the basement membrane network underlying epithelial and endothelial cells) by matrix metalloproteinase-7 (MMP-7, an enzyme upregulated in invasive prostate cancer cells) serves as a trigger for cell dispersion and invasiveness [33]. Intact perlecan maintains tissue borders and also harbors a reservoir of heparan sulfate-bound growth factors critical for the normal wound healing response [26].…”

Proteoglycans in normal physiology and carcinogenesis

“…In vitro по-казано, что в регуляции экспрессии корового белка гена HSPG2 участвует цитокин TNF-α (фактор некро-за опухоли альфа), что говорит о возможном вовлече-нии перлекана в цитокинопосредованные реакции, влияющие на инвазию клеток РПЖ [91]. В опухолях предстательной железы уровни матриксной металло-протеиназы 7 и перлекана высоко коррелируют между собой, а ферментативная обработка перлекана мат-риксной металлопротеиназой 7, как это происходит в микроокружении инвазивных опухолей, является молекулярным переключателем для изменения пове-дения клеток РПЖ и благоприятствует их инвазии [92]. В сыворотке больных РПЖ обнаружен повышенный уровень фрагментов перлекана (причем большинство из домена IV) по сравнению с нормальной сывороткой, что указывает на его деградацию в процессе метаста-зирования и может служить одним из критериев ин-вазивного РПЖ [93].…”