Shunya Kondo

The Membrane-Anchored MMP Inhibitor RECK Is a Key Regulator of Extracellular Matrix Integrity and Angiogenesis

Matrix metalloproteinases (MMPs) are essential for proper extracellular matrix remodeling. We previously found that a membrane-anchored glycoprotein, RECK, negatively regulates MMP-9 and inhibits tumor invasion and metastasis. Here we show that RECK regulates two other MMPs, MMP-2 and MT1-MMP, known to be involved in cancer progression, that mice lacking a functional RECK gene die around E10.5 with defects in collagen fibrils, the basal lamina, and vascular development, and that this phenotype is partially suppressed by MMP-2 null mutation. Also, vascular sprouting is dramatically suppressed in tumors derived from RECK-expressing fibrosarcoma cells grown in nude mice. These results support a role for RECK in the regulation of MMP-2 in vivo and implicate RECK downregulation in tumor angiogenesis.

RECK: A novel suppressor of malignancy linking oncogenic signaling to extracellular matrix remodeling

RECK was first isolated as a transformation suppressor gene by cDNA expression cloning in a mouse fibroblast cell line transformed by an activated RAS oncogene. Subsequently, reduced expression of RECK in transformed cells and cancer cells were demonstrated. Moreover, in several types of tumors, positive correlation between RECK expression and survival of patients have been noted. RECK encodes a GPI-anchored glycoprotein harboring three protease inhibitor-like domains. The RECK protein regulates at least three members of the matrix metalloproteinase (MMP) family, MMP-2, MMP-9, and MT1-MMP, in vitro or in cultured cells. Restored expression of RECK in cancer cell lines results in strong suppression of invasion, metastasis, and tumor angiogenesis. Mice lacking RECK die in utero with reduced integrity of blood vessels, the neural tube, and mesenchymal tissues. In these mice, MMP activity is elevated, and the amount of collagen type I greatly reduced. The RECK null phenotype is partially rescued (half day delay of death and marked recovery of tissue integrity) by MMP-2 null mutation, demonstrating functional interaction between RECK and MMP-2 in vivo and involvement of other target(s) for RECK in the lethal phenotype. These findings indicate that (i) RECK is an important regulator of extracellular matrix remodeling and that (ii) down-regulation of RECK by oncogenic signaling leads to the excessive activation of MMPs thereby promoting malignant behavior of cancer cells such as invasion, metastasis, and angiogenesis.

Mutations in two matrix metalloproteinase genes, MMP-2 and MT1-MMP, are synthetic lethal in mice

The matrix metalloproteinase (MMP) family (∼25 members in mammals) has been implicated in extracellular matrix remodeling associated with embryonic development, cancer formation and progression, and various other physiological and pathological events. Inactivating mutations in individual matrix metalloproteinase genes in mice described so far, however, are nonlethal at least up to the first few weeks after birth, suggesting functional redundancy among MMP family members. Here, we report that mice lacking two MMPs, MMP-2 (nonmembrane type) and MT1-MMP (membrane type), die immediately after birth with respiratory failure, abnormal blood vessels, and immature muscle fibers reminiscent of central core disease. In the absence of MMP-2 and MT1-MMP, myoblast fusion in vitro is also significantly retarded. These findings suggest functional overlap in mice between the two MMPs with distinct molecular natures.

The Membrane-Anchored Matrix Metalloproteinase (MMP) Regulator RECK in Combination with MMP-9 Serves as an Informative Prognostic Indicator for Colorectal Cancer

Purpose: RECK, a membrane-anchored regulator of matrix metalloproteinases (MMPs), is widely expressed in healthy tissue, whereas it is expressed at lower levels in many tumor-derived cell lines. Studies in mice and cultured cells have shown that restoration of RECK expression inhibits tumor invasion, metastasis, and angiogenesis. However, the clinical relevance of these findings remains to be fully documented. Here we examined the expression of RECK and one of its targets, MMP-9, in colorectal cancer tissue. Experimental Design: The RECK and MMP-9 expression levels in colorectal cancer samples from 53 patients were determined by immunohistochemical techniques. The expression level of each protein was scored, and the patients were divided into two groups based on these scores. In 33 cases, we performed gelatin zymography to estimate the degree of MMP-2 and MMP-9 activation. Microvessel density and vascular endothelial growth factor (VEGF) expression were also evaluated histologically. Results: RECK protein was detected in 30 of 53 (56.6%) specimens. Importantly, patients with tumors expressing relatively high levels of RECK (high-RECK group) had a significantly lower risk of recurrence than did patients with tumors expressing relatively low levels of RECK (low-RECK group; P = 0.011). Moreover, RECK-dominant (RECK score ≥ MMP-9 score) patients showed a significantly lower incidence of recurrence than did MMP-9-dominant patients (P = 0.0003). Multivariate analysis revealed that the RECK/MMP-9 balance was an independent prognostic factor (P = 0.0122). The expression of VEGF and microvessel density were inversely correlated with the level of RECK expression. Conclusions: RECK/MMP-9-balance is an informative prognostic indicator for colorectal cancer. Our data also suggest that RECK suppresses tumor angiogenesis, probably by limiting the availability of VEGF in tumor tissues.

The membrane-anchored MMP-regulator RECK is a target of myogenic regulatory factors

The membrane-anchored MMP-regulator RECK is down regulated in many solid tumors; the extent of RECK down regulation correlates with poor prognosis. Forced expression of RECK in tumor cells results in suppression of angiogenesis, invasion, and metastasis. Studies on the roles and the mechanisms of regulation of the RECK gene during normal development may therefore yield important insights into how the malignant behaviors of tumor cells arise and how they can be controlled. Our previous studies indicate that mice lacking RECK die around E10.5 with reduced tissue integrity. In the present study, we have found that in later stage wild-type embryos, RECK is abundantly expressed in skeletal muscles, especially in the areas where the myoblast differentiation factor MRF4 is expressed. Consistent with this finding, the RECK-promoter is activated by MRF4 in cultured cells. In contrast, a myoblast determination factor MyoD suppresses the RECK-promoter. Myoblastic cells lacking RECK expression give rise to myotubes at higher efficiency than the cells expressing RECK, indicating that RECK suppresses myotube formation. These findings suggest that MyoD down regulates RECK to facilitate myotube formation, whereas MRF4 up regulates RECK to promote other aspects of myogenesis that require extracellular matrix integrity.

Dual effects of the membrane-anchored MMP regulator RECK on chondrogenic differentiation of ATDC5 cells

Extracellular matrix (ECM) undergoes continuous remodeling during mammalian development. Although involvement of matrix metalloproteinases (MMPs) in ECM degradation has been well documented, how this process is regulated to allow proper ECM accumulation remains unclear. We previously showed the involvement of a membrane-anchored MMP regulator, RECK (reversion-inducing cysteine-rich protein with Kazal motifs), in vascular development in mice. Here we report that Reck mRNA can be detected in developing cartilage in E13.5∼16.5 mouse embryos and is progressively upregulated during differentiation of a chondrogenic cell line ATDC5 in vitro. In the early phase of ATDC5 differentiation, RECK expression stays low, multiple MMPs are upregulated, and there is ECM degradation at the sites of cellular condensation. In the later phase, RECK is upregulated inside the expanding cartilaginous nodules where type II collagen is accumulated while active ECM degradation persists along the rim of the nodules. Constitutive RECK expression suppressed initial cellular condensation, whereas RECK knockdown suppressed the later ECM accumulation in the cartilaginous nodules. These results suggest that RECK expression at the right place (in the core of the nodules) and at the right time (only in the later phase) is important for proper chondrogenesis and that RECK, together with MMPs, plays a crucial role in regulating dynamic processes of tissue morphogenesis.

Involvement of the Reck tumor suppressor protein in maternal and embryonic vascular remodeling in mice

BackgroundDevelopmental angiogenesis proceeds through multiple morphogenetic events including sprouting, intussusception, and pruning. Mice lacking the membrane-anchored metalloproteinase regulator Reck die in utero around embryonic day 10.5 with halted vascular development; however, the mechanisms by which this phenotype arises remain unclear.ResultsWe found that Reck is abundantly expressed in the cells associated with blood vessels undergoing angiogenesis or remodelling in the uteri of pregnant female mice. Some of the Reck-positive vessels show morphological features consistent with non-sprouting angiogenesis. Treatment with a vector expressing a small hairpin RNA against Reck severely disrupts the formation of blood vessels with a compact, round lumen. Similar defects were found in the vasculature of Reck-deficient or Reck conditional knockout embryos.ConclusionsOur findings implicate Reck in vascular remodeling, possibly through non-sprouting angiogenesis, in both maternal and embyornic tissues.

Possible involvement of Rap1 and Ras in glutamatergic synaptic transmission.

Rap1A, first identified as a suppressor of transformed phenotype induced by an activated ras oncogene, is abundantly expressed in the brain. Its neurophysiological function, however, is poorly understood. When an activated Rap1A mutant (Rap1-12V) or a dominant negative H-Ras mutant (Ras-17N) was expressed in CA1 neurons in cultured hippocampal slices using the sindbis virus-mediated gene transfer technique, NMDA receptor current in response to Schaffer collateral stimulation was suppressed. Expression of activated H-Ras mutant (Ras-12V) resulted in the elevation of both NMDA receptor current and AMPA receptor current. These results implicate counteracting functions of Ras and Rap1 in the regulation of NMDA receptor-mediated synaptic transmission and a positive regulatory role of Ras in AMPA receptor-mediated synaptic transmission.

Stimulatory actions of lysophosphatidic acid on mouse ATDC5 chondroprogenitor cells

Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are bioactive lysophospholipids that affect various cellular processes through G protein-coupled receptors. In our current study, we found by in situ hybridization that E11.5 mouse embryos strongly expressed the LPA receptor subtype LPA1 in cartilaginous bone primordia and the surrounding mesenchymal cells. However, despite their wide-ranging actions, the roles of lysophospholipids in chondrogenesis remain poorly understood. The mouse clonal cell line ATDC5 undergoes a sequential differentiation of chondroprogenitor cells in vitro. Undifferentiated and differentiated ATDC5 cells express LPA1 and other lysophospholipid receptors including S1P receptor S1P1 and S1P2. Taking advantage of this cell model, we studied the effects of LPA on the activities of chondroprogenitor cells. LPA markedly stimulates both DNA synthesis and the migration of ATDC5 chondroprogenitor cells in culture, whereas S1P suppresses the migration of these cells. Treatment with Ki16425, an LPA1- and LPA3-specific receptor antagonist, suppressed the fetal bovine serum-stimulated migration of ATDC5 cells by almost 80%. These results indicate that LPA plays an important role in the activation of chondroprogenitor cells.

Effects of ras and rap1 on electrical excitability of differentiated ng108-15 cells

Effects of two small G-proteins, Rap1 and Ras, on the sodium channel activity in NG108-15 cells were studied using sindbis virus-mediated gene transfer. When an activated Rap1A mutant (Rap1-12V, the activated mutant of Rap1 carrying glycine to valine substitution at codon 12) or a dominant-negative H-Ras mutant (Ras-17N, carrying serine to asparagine substitution at codon 17) was expressed in differentiated NG108-15 cells, the proportion of cells generating action potential decreased and the amplitudes of sodium current diminished. This effect was sensitive to an inhibitor of protein kinase A. The effects of a cyclic AMP (cAMP) analog (dibutyl cAMP) on sodium current in these cells were biphasic: inhibitory at lower concentrations (<100 microM) and enhancing at higher concentrations (200-500 microM). The inhibitory phase of cAMP effect was suppressed by an activated Ras mutant (Ras-12V) while the enhancing phase was suppressed by Rap1-12V. These data are consistent with the model that Rap1 and Ras function as counteracting regulators of voltage-gated sodium current through cAMP-dependent mechanisms.