Methionine aminopeptidase­2 is a pivotal regulator of vasculogenic mimicry.

Vasculogenic mimicry (VM) is the formation of a blood supply system that confers aggressive and metastatic properties to tumors and correlates with a poor prognosis in cancer patients. Thus, the inhibition of VM is considered an effective approach for cancer treatment, although such a mechanism remains poorly described. In the present study, we examined methionine aminopeptidase­2 (MetAP2), a key factor of angiogenesis, and demonstrated that it is pivotal for VM, using pharmacological and genetic approaches. Fumagillin and TNP­470, angiogenesis inhibitors that target MetAP2, significantly suppressed VM in various human cancer cell lines. We established MetAP2­knockout (KO) human fibrosarcoma HT1080 cells using the CRISPR/Cas9 system and found that VM was attenuated in these cells. Furthermore, re­expression of wild­type MetAP2 restored VM in the MetAP2­KO HT1080 cells, but the substitution of D251, a conserved amino acid in MetAP2, failed to rescue the VM. Collectively, our results demonstrate that MetAP2 is critical for VM in human cancer cells and suggest fumagillin and TNP­470 as potent VM­suppressing agents.

Discovery of bactericides as an acute mitochondrial membrane damage inducer.

Mitochondria evolved from endosymbiotic bacteria to become essential organelles of eukaryotic cells. The unique lipid composition and structure of mitochondrial membranes are critical for the proper functioning of mitochondria. However, stress responses that help maintain the mitochondrial membrane integrity are not well understood. One reason for this lack of insight is the absence of efficient tools to specifically damage mitochondrial membranes. Here, through a compound screen, we found that two bis-biguanide compounds, chlorhexidine and alexidine, modified the activity of the inner mitochondrial membrane (IMM)-resident protease OMA1 by altering the integrity of the IMM. These compounds are well-known bactericides whose mechanism of action has centered on their damage-inducing activity on bacterial membranes. We found alexidine binds to the IMM likely through the electrostatic interaction driven by the membrane potential as well as an affinity for anionic phospholipids. Electron microscopic analysis revealed that alexidine severely perturbated the cristae structure. Notably, alexidine evoked a specific transcriptional/proteostasis signature that was not induced by other typical mitochondrial stressors, highlighting the unique property of alexidine as a novel mitochondrial membrane stressor. Our findings provide a chemical-biological tool that should enable the delineation of mitochondrial stress-signaling pathways required to maintain the mitochondrial membrane homeostasis.

Topical formulation containing Ilex Paraguariensis extract increases metalloproteinases and myeloperoxidase activities in mice exposed to UVB radiation.

Ultraviolet B radiation represents 10% of the total UV radiation that reaches the Earth's surface, being the primary responsible for the biological effects related to skin cancer and photoaging. Ilex Paraguariensis A. St. Hil., known as Yerba mate (YM), is a native tree of South America whose polyphenols in its leaves are described to exhibit photochemoprotective effect and are employed in the treatment of cancer. Additionally, the polyphenols are used to prevent lipid peroxidation and reduce the UV-induced damage, which ultimately decreases the oxidative stress. Thus, the present study aimed to characterize a new YM extract, evaluate the extract cytotoxicity and develop a formulation containing YM extract to prevent UVB-induced damage in mice skin. The YM extract showed high levels of polyphenols, flavonoids, and tannins and exhibited excellent antioxidant activity. Its main components were suggested as chlorogenic acid (1.92%) and caffeic acid (0.41%). Besides, YM extract did not exhibit cytotoxicity in fibroblasts and decreased the activity of myeloperoxidase and metalloproteinase-2 after acute UVB exposure. As a result, the formulation containing the YM extract showed a potential photochemoprotective.

Impaired flow-induced arterial remodeling in DOCA-salt hypertensive rats.

Arteries from young healthy animals respond to chronic changes in blood flow and blood pressure by structural remodeling. We tested whether the ability to respond to decreased (-90%) or increased (+100%) blood flow is impaired during the development of deoxycorticosterone acetate (DOCA)-salt hypertension in rats, a model for an upregulated endothelin-1 system. Mesenteric small arteries (MrA) were exposed to low blood flow (LF) or high blood flow (HF) for 4 or 7 weeks. The bioavailability of vasoactive peptides was modified by chronic treatment of the rats with the dual neutral endopeptidase (NEP)/endothelin-converting enzyme (ECE) inhibitor SOL1. After 3 or 6 weeks of hypertension, the MrA showed hypertrophic arterial remodeling (3 weeks: media cross-sectional area (mCSA): 10±1 × 10(3) to 17±2 × 10(3) µm(2); 6 weeks: 13±2 × 10(3) to 24±3 × 10(3) µm(2)). After 3, but not 6, weeks of hypertension, the arterial diameter was increased (Ø: 385±13 to 463±14 µm). SOL1 reduced hypertrophy after 3 weeks of hypertension (mCSA: 6 × 10(3)±1 × 10(3) µm(2)). The diameter of the HF arteries of normotensive rats increased (Ø: 463±22 µm) but no expansion occurred in the HF arteries of hypertensive rats (Ø: 471±16 µm). MrA from SOL1-treated hypertensive rats did show a significant diameter increase (Ø: 419±13 to 475±16 µm). Arteries exposed to LF showed inward remodeling in normotensive and hypertensive rats (mean Ø between 235 and 290 µm), and infiltration of monocyte/macrophages. SOL1 treatment did not affect the arterial diameter of LF arteries but reduced the infiltration of monocyte/macrophages. We show for the first time that flow-induced remodeling is impaired during the development of DOCA-salt hypertension and that this can be prevented by chronic NEP/ECE inhibition.

Hemorrhagic profile of the fibrinolytic alfimeprase after ischemia and reperfusion.

OBJECTIVE: Recanalization therapies for ischemic stroke have been slow to change clinical practice because of perceived and published risks of hemorrhage associated with lytic administration. We quantified alfimeprase in an acute ischemia-reperfusion model, as compared with recombinant tissue plasminogen activator, with hemorrhagic transformation as the primary endpoint and infarction volume and blood-brain barrier permeability as secondary endpoints. METHODS: Five groups were studied in a blinded fashion: alfimeprase at doses of 0.03 (n=8), 0.1 (n=11) and 0.3 mg/kg (n=8); recombinant tissue plasminogen activator at 1 mg/kg (n=9); carrier infused controls (n=9). The middle cerebral artery was occluded for 5 hours followed by removal of the suture for reperfusion. Drugs were infused immediately following reperfusion over a 10-minute period. Approximately 24 hours later, the animals were anesthetized and decapitated, and the brains were rapidly harvested and frozen. Serial brain sections were obtained and inspected for hemorrhages. Infarction and blood-brain barrier permeability were also evaluated in additional experiments in control, 0.1 mg/kg alfimeprase and 1 mg/kg recombinant tissue plasminogen activator-treated rats. RESULTS: The hemorrhagic transformation frequency, neurological deficit and the mortality rate of alfimeprase were significantly lower than for recombinant tissue plasminogen activator at the 0.03 mg/kg dose and not statistically different at the higher doses. Infarction and blood-brain barrier permeability were not significantly different among control, 0.1 mg/kg alfimeprase and recombinant tissue plasminogen activator. DISCUSSION: In this model, alfimeprase, a new fibrinolytic agent, exhibits a profile comparable to recombinant tissue plasminogen activator.

Imatinib inhibits colorectal cancer cell growth and suppresses stromal-induced growth stimulation, MT1-MMP expression and pro-MMP2 activation.

Tumor progress depends on the proliferation of cancer cells, their interactions with stroma and the proteolytic action of enzymes. Colon cancer is c-kit positive and responsive to the specific tyrosine kinase inhibitor imatinib. We investigated the effect of imatinib on the proliferation of a panel of epithelial colon cancer cell lines in presence and absence of the antimetabolite 5-FU, and the effect of conditioned media (CM) derived from colon stromal fibroblasts with and without previous exposure to imatinib. The effects of imatinib on gene expression of MMPs and TIMPs were also studied. Imatinib effectively inhibited the proliferation of all cell lines, showing IC(50) from 0.3 to 3 microM. Its combination with 5-FU significantly enhances the growth inhibition of the highly tumourigenic HT-29 cells. CM derived from stromal fibroblasts induced the proliferation of the HT-29 cells; this stimulatory effect was abolished upon treatment with CM obtained after exposure of fibroblasts to imatinib. Gene expression of MT1-, MT2-MMP and MMP-7 was also inhibited depending on the cell line, whereas that of TIMP-2 was not affected. CM stimulated MT1-MMP protein expression by HT-29; this stimulatory effect was suppressed in the presence of imatinib. Activation of pro-MMP2 to MMP2 in culture medium of HT-29 treated with CM was increased and this activity was inhibited in presence of imatinib. The obtained data showed that imatinib is a powerful inhibitor of human colon cancer cell growth and effectively suppresses the stromal-induced stimulation of cancer cell growth and activation of proMMP2. Further studies are warranted to evaluate the in vivo effects.

The peptidase inhibitor CGS-26303 increases endothelin converting enzyme-1 expression in endothelial cells through accumulation of big endothelin-1.

BACKGROUND AND PURPOSE: CGS-26303 inhibits endothelin converting enzyme (ECE)-1 more specifically than phosphoramidon. We have studied the effect of CGS-26303 on ECE-1 expression in bovine aortic endothelial cells. METHODS: ECE-1 activity and big endothelin (ET)-1 levels were measured by ELISA, ECE-1 expression using western and northern blot and promoter activity using transfection assays. KEY RESULTS: ECE-1 activity was completely inhibited by CGS-26303 25 microM and phosphoramidon 100 microM. CGS-26303 and phosphoramidon, though not thiorphan, a neutral endopeptidase (NEP) inhibitor, stimulated ECE-1 expression in cells (maximal effect at 16 h, 25 microM). Cycloheximide abolished that effect. CGS-26303 induced ECE-1 mRNA expression and ECE-1 promoter activity. CGS-35066, a selective ECE-1 inhibitor, mimicked the effects of CGS-26303, suggesting that the effect was specific to ECE-1 inhibition. Big ET-1 accumulated in the cells and in the supernatants after CGS-26303 treatment. Neither exogenously added ET-1 nor the blockade of their receptors with bosentan modified ECE-1 protein. When big ET-1 was added to cells, significant increases in ECE-1 protein content and ECE-1 promoter activity were found. Bosentan did not block those effects. CGS-26303 did not modify prepro-ET-1 expression. CGS-26303 and big ET-1 induced the same effects in human endothelial cells, at lower doses. CONCLUSIONS: These results suggest that the accumulation of big ET-1 is responsible for the effects of CGS-26303 on ECE-1 and they did not depend on NEP blockade. Changes in ECE-1 protein after the administration of CGS-26303 could lead to a decreased response in long-term treatments.

Methionine aminopeptidase 2 over-expressed in cholangiocarcinoma: potential for drug target.

Methionine aminopeptidases (MetAP) are proteases which remove the N-terminal methionine from newly synthesized proteins. Associations of MetAP2 with tumor progression of different cancers have been repeatedly reported. We aim to determine if MetAP2 is expressed in cholangiocarcinomas (CCA) and investigate to see if it would be a useful therapeutic target. We evaluated MetAP2 expression by immunohistochemistry in 82 patients of intrahepatic CCA. MetAP2 was expressed in bile ducts to various degrees. It was occasionally expressed with weak staining in normal bile duct epithelium but was strikingly over-expressed in dysplastic bile duct epithelia, primary and metastatic CCA tissues (p < 0.001). The increased expression of MetAP2 in proliferating bile duct was evident. All metastatic tumors had stronger expression of MetAP2 than the corresponding primary tumors. Fumagillin, a MetAP2 specific inhibitor, significantly inhibited cell proliferation in dose dependent manner and the degree of growth inhibition was dependent on the amount of cellular enzyme. The present study highlights the involvement of MetAP2 in an early event of carcinogenesis of CCA. The findings represent the first description of increased MetAP2 expression in CCA. The inhibition of enzyme activity using MetAP2 inhibitors may be a potential strategy for long-term control of tumor development and progression in CCA patients.

Local and systemic pathophysiological alterations induced by a serine proteinase from the venom of the snake Bothrops jararacussu.

The local and systemic pathophysiological alterations induced by BjussuSP-I, a thrombin-like serine proteinase from the venom of the snake Bothrops jararacussu, were assessed in mice. BjussuSP-I induced a mild edema but no local myonecrosis or hemorrhage. It did not induce any microvascular alteration in the cremaster muscle. Intramuscular injection of BjussuSP-I promoted an increase in the expression of proMMP-9, but it did not induce the activation of proMMP-2 or proMMP-9 synthesized in muscle tissue injected with a myotoxic phospholipase A(2) homolog. BjussuSP-I induced defibrin(ogen)ation upon intravenous and intramuscular injections, with reduction in plasma fibrinogen concentration and increments in the levels of fibrin degradation products and D-dimer. When compared with animals having normal coagulation, mice defibrin(ogen)ated by BjussuSP-I developed a slightly larger hemorrhagic lesion in the skin when injected with metalloproteinase BaP1. Intravenous injection of sublethal doses of BjussuSP-I promoted a series of behavioral and motor changes similar to those previously described for 'gyroxin', i.e. opisthotonus and a circular body movement along the longitudinal axis.

Role for macrophage metalloelastase in glomerular basement membrane damage associated with alport syndrome.

Alport syndrome is a glomerular basement membrane (GBM) disease caused by mutations in type IV collagen genes. A unique irregular thickening and thinning of the GBM characterizes the progressive glomerular pathology. The metabolic imbalances responsible for these GBM irregularities are not known. Here we show that macrophage metalloelastase (MMP-12) expression is >40-fold induced in glomeruli from Alport mice and is markedly induced in glomeruli of both humans and dogs with Alport syndrome. Treatment of Alport mice with MMI270 (CGS27023A), a broad spectrum MMP inhibitor that blocks MMP-12 activity, results in largely restored GBM ultrastructure and function. Treatment with BAY-129566, a broad spectrum MMP inhibitor that does not inhibit MMP-12, had no effect. We show that inhibition of CC chemokine receptor 2 (CCR2) receptor signaling with propagermanium blocks induction of MMP-12 mRNA and prevents GBM damage. CCR2 receptor is expressed in glomerular podocytes of Alport mice, suggesting MCP-1 activation of CCR2 on podocytes may underlie induction of MMP-12. These data indicate that the irregular GBM that characterizes Alport syndrome may be mediated, in part, by focal degradation of the GBM due to MMP dysregulation, in particular, MMP-12. Thus, MMP-12/CCR2 inhibitors may provide a novel and effective therapeutic stra-tegy for Alport glomerular disease.

Characterization of the StcE protease activity of Escherichia coli O157:H7.

The StcE zinc metalloprotease is secreted by enterohemorrhagic Escherichia coli (EHEC) O157:H7 and contributes to intimate adherence of this bacterium to host cells, a process essential for mammalian colonization. StcE has also been shown to localize the inflammatory regulator C1 esterase inhibitor (C1-INH) to cell membranes. We tried to more fully characterize StcE activity to better understand its role in EHEC pathogenesis. StcE was active at pH 6.1 to 9.0, in the presence of NaCl concentrations ranging from 0 to 600 mM, and at 4 degrees C to 55 degrees C. Interestingly, antisera against StcE or C1-INH did not eliminate StcE cleavage of C1-INH. Treatment of StcE with the proteases trypsin, chymotrypsin, human neutrophil elastase, and Pseudomonas aeruginosa elastase did not eliminate StcE activity against C1-INH. After StcE was kept at 23 degrees C for 65 days, it exhibited full proteolytic activity, and it retained 30% of its original activity after incubation for 8 days at 37 degrees C. Together, these results show the StcE protease is a stable enzyme that is probably active in the environment of the colon. Additionally, k(cat)/K(m) data showed that StcE proteolytic activity was 2.5-fold more efficient with the secreted mucin MUC7 than with the complement regulator C1-INH. This evidence supports a model which includes two roles for StcE during infection, in which StcE acts first as a mucinase and then as an anti-inflammatory agent by localizing C1-INH to cell membranes.

Purification and characterization of a staphylokinase variant, K35R.

DGR [staphylokinase (Sak) variant K35R, in which lysine (K) at position 35 is replaced by arginine (R)], a recombinant mutant of the Staphylococcus aureus enzyme, is a promising drug for thrombotic disorders. In the present work, DGR was successfully overexpressed by the plasmid JF1125[pST-DGR] as a soluble cytoplasmic protein in a 30-litre fermentor that accounted for more than 50% of the total cellular protein. The expressed DGR was subsequently purified by using a simple three-step chromatographic purification process developed at a pilot scale. The clearance of host-cell-protein contaminants in the protein purification process was confirmed by SDS/PAGE and Western blotting, using rabbit antisera raised against Escherichia coli JF1125 cell proteins. SDS/PAGE, isoelectric focusing and HPLC-MS analysis indicated that the purified DGR is almost completely homogeneous. The purification process resulted in greater-than-98% pure DGR and yielded up to 25.0 mg/g wet weight of cells. The effect of pH and temperature on the stability of DGR was investigated further. The results showed that DGR was highly stable at neutral pH and more stable than two other wild-type Saks, SakSTAR and Sak42D, when submitted to high temperatures.

Up-regulation in endothelin-1 by Helicobacter pylori lipopolysaccharide interferes with gastric mucin synthesis via epidermal growth factor receptor transactivation.

OBJECTIVE: Endothelin-1 (ET-1), a key mediator of inflammatory processes associated with bacterial infection, is a 21-amino acid peptide produced from a biologically inactive big ET-1 by the action of endothelin-converting enzyme-1 (ECE-1) that acts through G protein-coupled ET(A) and ET(B) receptors. Here we report on the role of ET-1 in the mediation of the detrimental influence of Helicobacter pylori on the synthesis of gastric mucin. MATERIAL AND METHODS: Rat gastric mucosal cells were exposed to H. pylori key virulence factor, lipopolysaccharide (LPS). RESULTS: The LPS inhibitory effect on gastric mucin synthesis was accompanied by a marked increase in ET-1 generation and enhancement in ECE-1 activity. Inhibition of ECE-1 with phosphoramidon not only led to the impedance of LPS-induced ET-1 generation, but also countered the detrimental effect of LPS on mucin synthesis. Moreover, the LPS inhibitory effect on mucin synthesis was blocked by ET(A) receptor antagonist BQ610, but not by ET(B) receptor antagonist BQ788. Furthermore, the LPS-induced suppression in gastric mucin synthesis was countered in a concentration-dependent fashion by PD153035 (81.7%), a specific inhibitor of epidermal growth factor receptor (EGFR) kinase as well as PP2 (69.8%), a selective inhibitor of tyrosine kinase Src responsible for ligand-independent EGFR transactivation. CONCLUSIONS: Our findings are the first to show that the detrimental effect of H. pylori on gastric mucin synthesis is intimately linked to the events associated with ECE-1 up-regulation, enhancement in ET-1 production, and G protein-coupled ET(A) receptor activation that triggers the EGFR transactivation.

Pentylenetetrazol-induced seizures affect the levels of prolyl oligopeptidase, thimet oligopeptidase and glial proteins in rat brain regions, and attenuation by MK-801 pretreatment.

The regulatory mechanisms of neuropeptide-metabolizing enzymes often play a critical role in the pathogenesis of neuronal damage. A systemic administration of pentylenetetrazol (PTZ), an antagonist of GABA(A) receptor ion channel binding site, causes generalized epilepsy in an animal model. In the present study, we examined the involvement of prolyl oligopeptidase (POP), thimet oligopeptidase/neurolysin (EP 24.15/16) and glial proteins in PTZ-treated rat brain regions, and the suppressive effect of MK-801, a non-competitive NMDA receptor antagonist, pretreatment for their proteins. The activity of POP significantly decreased in the hippocampus at 30min and 3h, and in the frontal cortex at 3h after PTZ treatment, and pretreatment with MK-801 recovered the activity in the cortex at 3h. The activity of EP 24.15/16 significantly decreased in the hippocampus at 3h and 1 day, and in the cortex at 3h after the PTZ administration, whereas pretreatment with MK-801 recovered the change of the activity. The Western blot analysis of EP 24.15 showed significant decrease of the protein level in the hippocampus 3h after the PTZ treatment, whereas pretreatment with MK-801 recovered. The expression of GFAP and CD11b immunohistochemically increased in the hippocampus of the PTZ-treated rat as compared with controls. Pretreatment with MK-801 also recovered the GFAP and CD11b expression. These data suggest that PTZ-induced seizures of the rats cause indirect activation of glutamate NMDA receptors, then decrease POP and EP 24.15/16 enzyme activities and EP 24.15 immunoreactivity in the neuronal cells of the hippocampal formation. We speculate that changes of those peptidases in the brain may be related to the levels of the neuropeptides regulating PTZ-induced seizures.

Inhibition of gelatinase B (matrix metalloproteinase-9) by dihydrolipoic acid.

Alpha-lipoic acid (LA) is a disulphide-containing fatty acid that is absorbed from the diet and transported to tissues. Once it has been taken up by mammalian cells, LA is reduced to dihydrolipoic acid (DHLA), a vicinal dithiol, and rapidly effluxed into the extracellular milieu. We hypothesized that DHLA may be an effective inhibitor of human gelatinase B (GelB). Purified human GelB was incubated with 0 to 200 micromol/L DHLA, and residual enzyme activity was measured by HPLC using a fluorogenic substrate (matrix metalloproteinase substrate III). DHLA inhibited GelB in a dose-dependent fashion with an IC50 of 20 micromol/L. Oxidation of DHLA resulted in a loss of DHLA's capacity to inhibit GelB. The DHLA-mediated inhibition of GelB was independent of the zinc concentration in the reaction buffer. DHLA had no inhibitory effect on gelatinase A. Zymographs of activated neutrophil lysates demonstrated that higher concentrations of DHLA also prevent the activation of GelB proenzyme. Bronchoalveolar lavage fluid from mice fed a diet enriched with LA showed significantly increased GelB inhibitory capacity (p = 0.0002 vs. regular diet). We conclude that DHLA can modulate neutrophil-derived GelB activity through direct inhibition of enzyme activity and by preventing the activation of GelB proenzyme.

Elastin-derived peptides enhance angiogenesis by promoting endothelial cell migration and tubulogenesis through upregulation of MT1-MMP.

Elastin-derived peptides display a wide range of biological activities in a number of normal and transformed cells but their involvement in angiogenesis has not been reported. In the present study, we show that kappa-elastin and VGVAPG hexapeptide elastin motif accelerated angiogenesis in the chick chorio-allantoic membrane in an in vivo model. They also stimulated pseudotube formation from human vascular and microvascular endothelial cells in the matrigel and collagen models as well as cell migration in an in vitro wound healing assay. Confocal and scanning electron microscopy analyses revealed the main reorganization of actin filaments mediated by elastin-derived peptides and changes in cell shape that correlated with a decrease of the cell form factor determined by computerized image analysis. Such elastin-derived peptide effects were attributed to upregulation of proMT1-MMP and proMMP-2 expression and activation at both the mRNA and protein levels. Batimastat, an inhibitor of furin convertase and TIMP-2, but not TIMP-1, totally abolished the influence of elastin-derived peptides (EDPs) on cell migration and tubulogenesis, thus favoring the involvement of MT1-MMP in such processes. To assess its contribution to EDP-mediated angiogenesis further, we used a small interfering RNA (siRNA) approach for specifically silencing MT1-MMP in human microvascular endothelial cells. Four sets of 21 bp siRNA duplexes targeting MT1-MMP mRNA were synthesized by in vitro transcription. Two of them proved to inhibit MT1-MMP expression efficiently but did not affect MT2-, MT3- and MT5-MMP expression. Seventy-two hours after transfection with 25 nM siRNAs EDP-induced MT1-MMP expression at the mRNA and protein levels was decreased fourfold. In parallel, proMMP-2 activation was inhibited. A scrambled siRNA, used as a negative control, had no effect. Finally, the effect of elastin peptides on pseudotube formation in MT1-MMP-siRNA transfected cells was totally abolished. These data emphasise the crucial role of MT1-MMP in the elastin-induced angiogenic phenotype of endothelial cells.

ADAM12 and alpha9beta1 integrin are instrumental in human myogenic cell differentiation.

Knowledge on molecular systems involved in myogenic precursor cell (mpc) fusion into myotubes is fragmentary. Previous studies have implicated the a disintegrin and metalloproteinase (ADAM) family in most mammalian cell fusion processes. ADAM12 is likely involved in fusion of murine mpc and human rhabdomyosarcoma cells, but it requires yet unknown molecular partners to launch myogenic cell fusion. ADAM12 was shown able to mediate cell-to-cell attachment through binding alpha9beta1 integrin. We report that normal human mpc express both ADAM12 and alpha9beta1 integrin during their differentiation. Expression of alpha9 parallels that of ADAM12 and culminates at time of fusion. alpha9 and ADAM12 coimmunoprecipitate and participate to mpc adhesion. Inhibition of ADAM12/alpha9beta1 integrin interplay, by either ADAM12 antisense oligonucleotides or blocking antibody to alpha9beta1, inhibited overall mpc fusion by 47-48%, with combination of both strategies increasing inhibition up to 62%. By contrast with blockade of vascular cell adhesion molecule-1/alpha4beta1, which also reduced fusion, exposure to ADAM12 antisense oligonucleotides or anti-alpha9beta1 antibody did not induce detachment of mpc from extracellular matrix, suggesting specific involvement of ADAM12-alpha9beta1 interaction in the fusion process. Evaluation of the fusion rate with regard to the size of myotubes showed that both ADAM12 antisense oligonucleotides and alpha9beta1 blockade inhibited more importantly formation of large (> or =5 nuclei) myotubes than that of small (2-4 nuclei) myotubes. We conclude that both ADAM12 and alpha9beta1 integrin are expressed during postnatal human myogenic differentiation and that their interaction is mainly operative in nascent myotube growth.

Matrilysin (MMP-7) promotes invasion of ovarian cancer cells by activation of progelatinase.

Although matrilysin (MMP-7) is overexpressed in various malignancies, few studies have evaluated its role in epithelial ovarian cancer (EOC) invasion and metastasis. We report that the secretion of MMP-7 in EOC is stimulated significantly by vascular endothelial growth factor (VEGF) and interlukin-8 (IL-8). We also examined the in vivo expression of MMP-7 in EOC and its effects on the in vitro invasion and progelatinase activation. We report that MMP-7 is overexpressed in ovarian cancer cell lines and EOC surgical specimens. DOV13 cells incubated with active rhMMP-7 significantly increased cellular invasion and proMMP-2 activation. RhMMP-7 also showed the ability to activate proMMP-2 and proMMP-9 in immortalized ovarian epithelial cell (IOSE-29) conditioned medium. In addition, rhMMP-7 was able to activate progelatinase in a concentration-dependent manner in vitro. TIMP-2 or the generic MMP inhibitor-GM6001 inhibited both the activation of proMMP-2 and the increased invasion of DOV13 cells promoted by rhMMP-7. By incubation of MMP2-TIMP-2 complex with equal molar rhMMP-7, MMP-2 was dissociated from the complex and activated in a time-dependent manner, suggesting that TIMP-2 helps to keep the latency of MMP-2. TIMP-2 also showed inhibitory effects on the MMP-7 induced increase of gelatinolytic activity in DOV13 and IOSE-29 conditioned media. A strong co-localization of MMP-7 and MMP-2 was observed in DOV13 cells and ovarian carcinoma permanent tissue sections. These results indicate MMP-7 is overexpressed in malignant ovarian epithelium and suggest MMP-7 may facilitate tumor cell invasion in vivo partly through the induction of progelatinase activation.

The C. elegans methionine aminopeptidase 2 analog map-2 is required for germ cell proliferation.

We have investigated the physiological function of type 2 methionine aminopeptidases (MetAP2) using Caenorhabditis elegans as a model system. A homolog of human MetAP2 was found in the C. elegans genome, which we termed MAP-2. MAP-2 protein displayed methionine aminopeptidase activity and was sensitive to inhibition by fumagillin. Downregulation of map-2 expression by RNAi led to sterility, resulting from a defect in germ cell proliferation. These observations suggest that MAP-2 is essential for germ cell development in C. elegans and that this ubiquitous enzyme may play important roles in a tissue specific manner.