Expression of Matrix Metalloproteinases and Their Inhibitors in Medulloblastomas and Their Prognostic Relevance O ¨ zlem O ¨ zen, 1 Bjarne Krebs, 1 Bernhard Hemmerlein, 2 Arnulf Pekrun, 3 Hans Kretzschmar, 1 and Jochen Herms 1 1 Zentrum fu ¨r Neuropathologie, Ludwig Maximilians Universita ¨t Mu ¨nchen, Munich, 2 Institut fu ¨r Pathologie, and 3 Zentralkrankenhaus St. Ju ¨rgenstrasse, Zentrum fu ¨r Kinderheilkunde, Byemen, Universita ¨t Go ¨ttingen, Go ¨ttingen, Germany ABSTRACT Purpose and Experimental Design: The cellular mecha- nisms leading to metastatic disease in medulloblastoma (MB), the most common malignant brain tumor in child- hood, are mainly unknown. Recently, however, the involve- ment of matrix metalloproteinases (MMPs) has been sug- gested. We examined the expression and localization of four MMPs—MMP-2 and -9, membrane-type 1 and 2 MMP (MT1- and MT2-MMP)—and correlated the data with those for their main inhibitors, tissue inhibitors of metalloprotein- ases (TIMP-1, -2, and -3), in 83 classical and 18 desmoplastic MBs. Results: Independent of the histological subtype, MMP-2 expression was found in a small percentage of tu- mors, whereas MMP-9 and MT1- or MT2-MMP were ex- pressed in >75% of tumor samples. The expression of TIMP-1, -2, and -3, on the other hand, was found to depend on the histological subtype: TIMP-3 was often found in classical MB, whereas TIMP-2 was often expressed in des- moplastic MB (P  0.007– 0.001). In addition, both TIMP-3 and -2 correlated significantly with the expression of all studied metalloproteinases except MMP-2. TIMP-1, de- tected only in classical MB in a low percentage, was the only TIMP that correlated with the expression of MMP-2. Kaplan–Meier estimation revealed significantly reduced long-term survival of patients with strong MMP expression in tumor samples. In multivariate logistic regression analy- sis, however, the prognosis was significantly determined only by clinical parameters. Conclusions: TIMP-3 and -2 expression is highly corre- lated with histological subtypes of MBs and strongly associ- ated with the expression of certain MMPs. The expression of TIMPs and MMPs, however, does not determine prognosis independently of clinical parameters. INTRODUCTION Medulloblastoma (MB), the most common malignant brain tumor in childhood, comprises up to 25% of all intracranial neoplasms and is defined as a small blue-cell tumor arising in the cerebellum. Despite recent improvements in the survival of patients with MB, secondary tumor growth is observed in up to 40% of patients, resulting in a poor prognosis. Dissemination to the leptomeninges of the brain or seeding of tumor cells in the neuroaxis are the most common forms of metastasis (1–5). The underlying molecular mechanisms of brain tumor invasiveness are complex and have been studied mainly in malignant glial tumors and are closely related to proteolytic degradation of the extracellular matrix (ECM; Ref. 6). The ECM accounts for up to 20% of the total volume of the central nervous system and is composed of glycoproteins and proteoglycans that are secreted into a network to which cells adhere. This network consists predominantly of the proteins fibronectin, laminin, vitronectin, thrombospondin, tenascin, heparin sulfate proteoglycan, and collagen IV (7). Several proteases are thought to be involved in the degradation of ECM components, including matrix metal- loproteinases (MMPs), serine proteinases (urokinase and tissue plasminogen activators), cysteine proteinases (cathepsin B and S), aspartic proteinases (cathepsin D), and glycosidases (8). Among these, MMPs are thought to play a major role in tumor invasion and metastasis (9 –14). The MMPs constitute a multigene family of 25 secreted and cell surface enzymes that process or degrade various peri- cellular substrates (15). Their targets include other proteinases, proteinase inhibitors, clotting factors, chemotactic molecules, latent growth factors, growth factor-binding proteins, cell sur- face receptors, cell– cell adhesion molecules, and almost all structural ECM proteins (15). Collagenases; gelatinases; mem- brane-type MMPs (MT-MMPs); matrilysin; stromelysin-1, -2, and -3; and metalloelastase are members of the MMP family (7). All MMPs contain at least three protein domains: a “pre” domain that is cleaved after it directs synthesis of the MMP to the endoplasmic reticulum; a “pro” domain that maintains en- zyme latency until it is removed or inhibited; and a catalytic domain that contains a conserved zinc-binding region. MMPs are often classified according to these structural domains (15). Under normal conditions, MMPs are tightly regulated at the levels of gene transcription, activation of inactive zymogens, and inhibition by tissue inhibitors of metalloproteinases (TIMPs; Refs. 7, 8, 15–17). TIMPs are a family of secreted glycoproteins that includes at least four members, TIMP-1, -2, -3, and -4. All of the TIMPs form high-affinity, noncovalent, and essentially irreversible complexes with the active forms of MMPs with a 1:1 stoichiometry (7, 8, 15, 16). TIMP-1 and -2 Received 4/23/03; revised 4/15/04; accepted 4/26/04. Grant support: Supported by the Deutsche Krebshilfe. O ¨ .O ¨ zen was financially supported by a grant from the Deutsche Forschungsgemein- schaft and the Scientific and Technical Research Council of Turkey. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Requests for reprints: Jochen Herms, Zentrum fu ¨r Neuropathologie, Ludwig-Maximilians-Universita ¨t, Feodor-Lynen Strasse 23, 81377 Mu ¨nchen, Germany. Phone: 49-089-2180-78010; Fax: 49-089-2180- 78037; E-mail: Jochen.Herms@med.uni-muenchen.de. 4746 Vol. 10, 4746 – 4753, July 15, 2004 Clinical Cancer Research Research. on July 19, 2018. © 2004 American Association for Cancer clincancerres.aacrjournals.org Downloaded from