Hintergrund: Die Matrix-Metalloproteinase–9 (MMP–9) spielt eine zentrale Rolle im Rahmen der Metastasierung. In hepatozellulären Karzinomen konnte eine Überexpression von MMP–9 gezeigt werden. Ziel der vorliegenden Untersuchung war, zu klären, ob eine leberspezifische Überexpression von MMP–9 die Empfindlichkeit der Leber gegenüber chemisch induzierter Karzinogenese verändert.

Einleitung: Umbau extrazellulärer Matrix stellt einen entscheidenden Schritt im Rahmen der Leberfibrogenese und der -karzinogenese dar. Gegenstand zahlreicher Untersuchungen ist die Rolle der Matrix-Metalloproteinase–9 (MMP–9) in diesem Kontext. Ein geeignetes Tiermodell, welches erlaubt, den Einfluss von MMP–9 in vivo näher zu untersuchen, stand bislang noch nicht zur Verfügung. Es wurde daher ein konditionales Mausmodell mit leberspezifischer Überexpression von MMP–9 entwickelt.

04C. Molecular and cellular biology (e) HSCs and fibrosis S131GPO10 on cell functions and its potential to release and activate collagenbound proMMP-2.Methods: Sequential slices of cirrhotic liver tissues were incubated with Cy2-1abelled proMMP-2• pmoles GPO10.Slides were washed and collagen-bound fluorescent proMMP-2 was detected microscopically at 520nm.For control, collagens were stained by SiriusRed without proMMP-2.The ability of GPO10 to activate proMMP-2 was tested by an increased invasion capability after matrix degradation.Cells of the fibrosarcoma cell line HT1080 were cultured in a gradient from 0.25% to 10% fetal calf serum, and in the presence of GPO10 or the gelatinase inhibitor Ilomastat.Effects on cellular proliferation were studied by [3H]-thymidine incorporation using the half-activated hepatic stellate cell line CFSC with MMP-2, GPO10 and GPO10-activated proMMP-2, alone or with Ilomastat.Results: (1) The extent of collagen-rich SiriusRed-stained fibrotic septa corresponded to the areas stained by Cy2-1abelled proMMP-2 in sequential tissue slides.Preincubation of the slides with GPO10 effectively prevented binding of fluorescent proMMP-2.Pre-bound enzyme was released by addition of a 10fold molar excess of GPO10.(2) In vitro, invasiveness of HT1080 cells to Matrigel was enhanced by 20% in the presence GPO10activated proMMP-2.In contrast, it was inhibited to 50% by Ilomastat.(3) Under serum-reduced conditions, the proliferation of CFSC was stimulated by MMP-2.Addition of Ilomastat reduced the [3H]-thymidine incorporation almost to background levels.The increase in CFSC proliferation mediated by GPO10 alone was about 75% of the MMP-2 control.Conclusions: Small peptides like GPO10 that mimic collagenous structural elements effectively modulate the activity of collagen-stored proMMP-2 and enable rapid activation of cells.Thus, GPO10 and related peptides/peptide analogues are promising tools for a specific degradation of extracellular matrix in liver fibrosis.