Regulation of matrix metalloproteinases during extracellular matrix turnover

In vivo testing of an injectable matrix gel for the treatment of shoulder cuff muscle fatty degeneration

INTRODUCTION

Extracellular matrix (ECM) gels have shown efficacy for the treatment of damaged tissues, most notably cardiac muscle. We hypothesized that the ECM gel prepared from skeletal muscle could be used as a treatment strategy for fatty shoulder cuff muscle degeneration.

METHODS

We conducted experiments to (1) evaluate host biocompatibility to ECM gel injection using a rat model and (2) examine the effect of ECM gel injection on muscle recovery after delayed repair of a released supraspinatus (SSP) tendon using a rabbit model.

RESULTS

The host biocompatibility to the ECM gel was characterized by a transient rise (first 2 weeks only) in several genes associated with macrophage infiltration, matrix deposition, and inflammatory cytokine production. By 8 weeks all genes had returned to baseline levels and no evidence of fibrosis or chronic inflammation was observed from histology. When gel injection was combined with SSP tendon repair, we observed a significant reduction (7%) in SSP muscle atrophy (24 + 3% reduction from uninjured) when compared with treatment with tendon repair only (31 + 7% reduction). Although fatty degeneration was elevated in both treatment groups, fat content trended lower (2%) in response to combined tendon repair and intramuscular ECM injection (4.1 + 2.1%) when compared with tendon repair only (6.1 + 2.9%). Transcriptome analysis revealed adipogenesis and osteoarthritis pathway activation in the repair only group. These key pathways were abrogated in response to treatment using combined repair plus gel.

DISCUSSION

The findings suggest that ECM injection had a modest but positive effect on muscle mass, fatty degeneration, and key cellular signaling pathways.

Ovarian expression, localization, and function of tissue inhibitor of metalloproteinase 3 (TIMP3) during the periovulatory period of the human menstrual cycle

Ovulation involves reorganization of the extracellular matrix of the follicle. This study examines the expression, localization, and potential function of the tissue inhibitor of metalloproteinase 3 (TIMP3) during ovulation in women. The dominant follicle of the menstrual cycle was collected at specified times throughout the ovulatory process: pre-, early, late, and postovulatory. For quantitative studies, the follicle was bisected; granulosa and theca cells were separated and collected. For immunohistochemistry (IHC), the intact follicle was embedded and TIMP3 was localized. Additionally, granulosa cells were collected from women undergoing in vitro fertilization and treated with increasing concentrations of recombinant TIMP3, and cell viability was assessed. Real-time PCR for TIMP3 mRNA revealed an increase in TIMP3 mRNA expression in granulosa cells from the early to the late ovulatory stage. Thecal TIMP3 mRNA expression was constitutive across the periovulatory period. TIMP3 protein was localized by IHC to the granulosa and theca cell layers in pre-, early, and late ovulatory follicles as well as to the vascular bed. The staining was most intense in the granulosa and theca cells in the late ovulatory group. Treatment of human granulosa-lutein cells with exogenous recombinant TIMP3 for 24 h decreased cell viability by 60%. Using human follicles collected throughout the periovulatory period of the menstrual cycle, we have demonstrated that TIMP3 mRNA expression increases and that TIMP3 protein is in the appropriate cellular layers to regulate proteolytic remodeling as the follicle progresses toward ovulation. In addition, we have shown that elevated levels of TIMP3 lead to decreased cell viability.

Gingipain-dependent interactions with the host are important for survival of Porphyromonas gingivalis

Porphyromonas gingivalis, a major periodontal pathogen, must acquire nutrients from host derived substrates, overcome oxidative stress and subvert the immune system. These activities can be coordinated via the gingipains which represent the most significant virulence factor produced by this organism. In the context of our contribution to this field, we will review the current understanding of gingipain biogenesis, glycosylation, and regulation, as well as discuss their role in oxidative stress resistance and apoptosis. We can postulate a model, in which gingipains may be part of the mechanism for P. gingivalis virulence.

Activation of the estrogen receptor contributes to the progression of pulmonary lymphangioleiomyomatosis via matrix metalloproteinase-induced cell invasiveness

CONTEXT

The role of estrogens in the pathogenesis of lymphangioleiomyomatosis (LAM), an aggressive and destructive, eventually fatal lung disease of women, is poorly understood.

OBJECTIVE

The study was conducted to test the hypothesis that the lung disease in LAM is estrogen mediated and to determine whether estrogens contribute to the invasiveness of LAM.

DESIGN

In vitro cell culture of spindle-shaped LAM cells (LAMD-SM) were isolated and propagated from affected lungs. Estrogen receptor (ER)-alpha and ERbeta analyses were conducted by RT-PCR. ERalpha and ERbeta, tissue inhibitor of metalloproteinase-2, and matrix metalloproteinases (MMP)-2 had Western blot analysis for protein assessment. Activity assays were performed for MT1-MMP, MMP-2, and tissue inhibitor of metalloproteinase-2. Assessment of MMP-2 promoter function was done via transfection assays. Cell invasion chambers were used to determine and quantitate cell invasiveness.

SETTING

The study was conducted at an academic medical center.

PATIENTS

Tissue and cells were obtained from patients as outlined in approved institution review board protocol (97/007).

INTERVENTION

LAMD-SM cells were treated with a specific MMP-2 antibody or a nonspecific inhibitor, doxycycline.

MAIN OUTCOME MEASURES

Activity of MMP-2 and invasiveness of LAMD-SM cells were measured.

RESULTS

LAMD-SM cells express functional ERs (ERalpha and ERbeta), which undergo rapid intracellular turnover in their unbound state. 17beta-estradiol (E(2)) enhances the transcriptional ER activity. E(2)-induced ER activation increases synthesis and activity of MMP-2 through posttranscriptional mechanisms in LAMD-SM. The E(2)/ER-mediated increase of MMP-2 promotes LAMD-SM invasiveness, in assays in vitro, which can be inhibited by specific antibodies against MMP-2 or doxycycline, an inhibitor of MMPs.

CONCLUSION

The invasion and destruction of lung parenchyma in LAM is, at least partially, an estrogen-MMP-driven process, which has major implications for therapeutic interventions.

Effects of the matrix metalloproteinase inhibitor GM6001 on the destruction and alteration of epithelial basement membrane during the healing of post-alkali burn in rabbit cornea

PURPOSE

To examine the alteration in structure and matrix composition of epithelial basement membrane (BM) during the healing of alkali-burned rabbit cornea, and the roles of matrix metalloproteinases (MMPs) in these alterations.

METHODS

The central cornea of one eye of 78 albino rabbits was exposed to 1 N NaOH for 180 s under general and topical anesthesia and allowed to heal with or without subconjunctival injection of GM6001 (an MMP inhibitor). Cryosections of affected corneas were observed by H&E staining, immunohistochemistry for type IV collagen subtypes, or in situ zymography for detection of localization of MMP activity.

RESULTS

Uninjured corneal epithelial BM exhibited alpha5 (IV)-immunoreactivity, but lacked the alpha1/alpha2-immunoreactivity of collagen IV. Epithelial BM in healing burned cornea transiently exhibited alpha1/alpha2-immunoreactivity. Examination by in situ zymography showed an upregulation of MMP activity in the regenerated central epithelium and anterior stroma of the burned corneas at days 7 and 14. GM6001 suppressed degradation of alpha5-containing epithelial BM in vivo and also in organ culture.

CONCLUSIONS

Epithelial BM was degraded by endogenous MMPs during healing following an alkali burn in rabbit cornea. GM6001 had an inhibitory effect on the degradation of the epithelial basement membrane in burned cornea in vivo.

Inactivation of vimF, a putative glycosyltransferase gene downstream of vimE, alters glycosylation and activation of the gingipains in Porphyromonas gingivalis W83

Regulation/activation of the Porphyromonas gingivalis gingipains is poorly understood. A 1.2-kb open reading frame, a putative glycosyltransferase, downstream of vimE, was cloned, insertionally inactivated using the ermF-ermAM antibiotic resistance cassette, and used to create a defective mutant by allelic exchange. In contrast to the wild-type W83 strain, this mutant, designated P. gingivalis FLL95, was nonpigmented and nonhemolytic when plated on Brucella blood agar. Arginine- and lysine-specific gingipain activities were reduced by approximately 97% and 96%, respectively, relative to that of the parent strain. These activities were unaffected by the growth phase, in contrast to the vimA-defective mutant P. gingivalis FLL92. Expression of the rgpA, rgpB, and kgp gingipain genes was unaffected in P. gingivalis FLL95 in comparison to the wild-type strain. In nonactive gingipain extracellular protein fractions, multiple high-molecular-weight proteins immunoreacted with gingipain-specific antibodies. The specific gingipain-associated sugar moiety recognized by monoclonal antibody 1B5 was absent in FLL95. Taken together, these results suggest that the vimE downstream gene, designated vimF (virulence modulating gene F), which is a putative glycosyltransferase group 1, is involved in the regulation of the major virulence factors of P. gingivalis.

Activation of a phytopathogenic bacterial effector protein by a eukaryotic cyclophilin

Innate immunity in higher plants invokes a sophisticated surveillance system capable of recognizing bacterial effector proteins. In Arabidopsis, resistance to infection by strains of Pseudomonas syringae expressing the effector AvrRpt2 requires the plant resistance protein RPS2. AvrRpt2 was identified as a putative cysteine protease that results in the elimination of the Arabidopsis protein RIN4. RIN4 cleavage serves as a signal to activate RPS2-mediated resistance. AvrRpt2 is delivered into the plant cell, where it is activated by a eukaryotic factor that we identify as cyclophilin. This activation of AvrRpt2 is necessary for protease activity. Active AvrRpt2 can then directly cleave RIN4.

The vimE gene downstream of vimA is independently expressed and is involved in modulating proteolytic activity in Porphyromonas gingivalis W83

Regulation/activation of the Porphyromonas gingivalis gingipains is poorly understood. A unique 1.3-kb open reading frame downstream of the bcp-recA-vimA transcriptional unit was cloned, insertionally inactivated with the ermF-ermAM antibiotic resistance cassette, and used to create a defective mutant by allelic exchange. In contrast to the wild-type W83 strain, the growth rate of the mutant strain (designated FLL93) was reduced, and when plated on Brucella blood agar it was nonpigmented and nonhemolytic. Arginine- and lysine-specific gingipain activities were reduced by approximately 90 and 85%, respectively, relative to activities of the parent strain. These activities were unaffected by the culture's growth phase, in contrast to the vimA-defective mutant P. gingivalis FLL92, which has increased proteolytic activity in stationary phase. Expression of the rgpA, rgpB, and kgp gingipain genes was unaltered in P. gingivalis FLL93 compared to that of the wild-type strain. Further, in extracellular protein fractions a 64-kDa band was identified that was immunoreactive with the RgpB-specific proenzyme antibodies. Active-site labeling with dansyl-glutamyl-glycyl-arginyl chloromethyl ketone or immunoblot analysis showed no detectable protein band representing the gingipain catalytic domain. In vitro protease activity could be slightly induced by a urea denaturation-renaturation cycle in an extracellular protein fraction, in contrast to the vimA-defective mutant P. gingivalis FLL92. Expression of flanking genes, including recA, vimA, and Pg0792, was unaltered by the mutation. Taken together, these results suggest that the vimA downstream gene, designated vimE (for virulence-modulating gene E), is involved in the regulation of protease activity in P. gingivalis.

Matrix metalloproteinases in renal development

Matrix metalloproteinases (MMPs) are enzymes with metal ion-dependent activity that degrade extracellular matrix (ECM) glycoproteins. MMPs play a vital role in various biological processes, such as embryogenesis, tissue remodeling, angiogenesis, and wound healing, and in certain disease processes, for example, metastasis of cancer cells. Following their activation, MMPs are believed to modulate both cell-cell and cell-matrix interactions, which in turn regulate cellular differentiation, migration, proliferation, and cell survival. Being involved in pericellular proteolysis, they maintain a gradient of ECM proteins by balancing ECM synthesis and degradation. Such a balance is critical for various mammalian developmental processes during embryonic life and also for the homeostasis of various organs and reparative processes in later life. During the past two decades the role of MMPs in the morphogenesis of various organs, including that of the metanephros, has been investigated extensively. Mammalian nephrogenesis comprises a series of intricate events characterized by a sustained remodeling and turnover of ECM, suggesting a potential role of MMPs in renal development. Conceivably, reciprocal inductive epithelial-mesenchymal interactions that take place at the very commencement of nephrogenesis are modulated by a number of ECM proteins. Their expression, especially at the epithelial-mesenchymal interface, are critical for metanephric development, and such a strategic expression is likely to be modified by a number of different macromolecules that exhibit spatiotemporal and stage-specific expression. Among them the most suitable candidate that could exert such a control would be MMPs. This review addresses the current status of our understanding of the functions and the role of MMPs in renal development.

Experimental hindlimb ischemia increases neutrophil-mediated matrix metalloproteinase activity: a potential mechanism for lung injury after limb ischemia

BACKGROUND

Acute limb ischemia initiates a systemic inflammatory response, including pulmonary polymorphonuclear leukocyte (PMN) sequestration and acute lung injury. Lung injury is partly attributed to release by PMN's of extracellular matrix (ECM) modifying metalloproteinases (MMPs). We hypothesized that acute hindlimb ischemia (HI) would increase MMP activity in the lung and other organs and that systemic neutrophil depletion before HI would block this effect.

STUDY DESIGN

Seventeen FVB/N Tie2/LacZ-182 SATO female mice were randomly divided into four groups: HI + PBS (Group 1), HI + antineutrophil antibody (Group 2), HI + isotype matched control antibody (Group 3), and no HI + PBS (Group 4). HI was achieved by unilateral femoral artery ligation. Neutrophil depletion was confirmed. Three days postligation, lung, liver, and kidney were harvested. MMP-2 and -9 expression and activation (gelatin zymography) and membrane type-1 MMP (MT1-MMP, western blotting) were quantified by densitometry and NIH Image Analysis software. Statistical significance was determined with an analysis of variance.

RESULTS

Zymograms revealed a 46% increase in pulmonary proMMP-9 in Group 1 versus Group 4 (6,107 +/- 472 [mean +/- SEM] densitometry units [DU] versus 3,287 +/- 675 DU, p < 0.05). A similar trend was observed for active MMP-9 (3,189 +/- 541 DU versus 1,417 +/- 927 DU, P = 0.16). Neutrophil depletion (Group 2) decreased proMMP-9 levels by 51% (2,996 +/- 314 DU versus 6,107 +/- 472 DU, p < 0.05) and active MMP-9 by 75% (810 +/- 444 DU versus 3,189 +/- 541 DU, p < 0.05) compared with Group 1. Active MMP-2 increased 51% after HI (Group 1, 3,230 +/- 86 DU versus Group 4, 1,599 +/- 327 DU, p < 0.05). Neutrophil depletion decreased the HI-induced activation of MMP-2 by 43% (Group 2, 1,829 +/- 471 DU versus Group 1, 3,230 +/- 86 DU, p < 0.05).

CONCLUSIONS

HI increases pulmonary proMMP-9, active MMP-9, and active MMP-2 levels. Neutrophil depletion blocks this effect. These data suggest that acute limb ischemia leads to PMN-mediated changes in MMP activity.

Paracrine regulation of matrix metalloproteinase expression in endometriosis

Following retrograde menstruation, shed endometrial tissue fragments attach to and invade the peritoneal surface to form established endometriotic lesions. With disease progression, the biochemically active lesions undergo remodeling and become fibrotic. Matrix metalloproteinase enzymes (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs) play a significant role in normal endometrial remodeling during menses. Anomalous expression of MMPs and TIMPs has been identified in endometriotic lesions as compared to their highly regulated expression in eutopic endometrium. The paracrine mechanisms regulating misexpression of MMPs and TIMPs by endometriotic lesions are, however, not well defined. Misexpression of the MMPs and TIMPs may be due to innate anomalies in the eutopic endometrium from women with endometriosis, in the resident immune cells and peritoneal cells that juxtapose the ectopic endometrium, and/or numerous substances present in peritoneal fluid of women with endometriosis. The majority of MMPs are under strict transcriptional regulation. Steroid hormones and cytokines appear to act on the MMP promoter, either independently or in consort, to provide both positive and negative regulation of these genes. Misregulated expression of MMPs and TIMPs is associated with a more aggressive phenotype and a cascade of events facilitating peritoneal extracellular matrix degradation and establishment or remodeling of endometriotic lesions. The mechanisms by which MMP and TIMP expression are misregulated warrant further investigation as such information may provide insight into novel therapeutic modalities for endometriosis.

Matrix metalloproteinases in colorectal cancer

Matrix metalloproteinases (MMPs) appear to play a key role in the development and progression of human malignancies. MMPs mediate the destruction of the extracellular matrix, which is an important early step in tumor invasion and metastasis. Growing evidence suggests that MMPs also have angiogenic activity and participate in the early stages of tumorigenesis and primary tumor growth. Investigations in experimental animal models have confirmed the importance of MMPs in the pathogenesis of colorectal cancer, and studies in humans show a direct association between increased MMP expression and tumor invasiveness, development of metastases, and shortened survival. In this review, the physiologic role of MMPs in normal tissues is examined and data supporting the role of MMPs in the pathogenesis of colorectal cancer are reviewed. The results of clinical trials with MMP inhibitors in colorectal cancer and promising areas for future investigation are also discussed.

Proteoglycans and orthodontic tooth movement

Proteoglycans represent an important and diverse family of extracellular matrix components within the connective tissues of the periodontium. This review focuses on the function and metabolism of the various proteoglycans in periodontal tissues, such as alveolar bone and periodontal ligament, and considers their potential fate in response to an orthodontic force. Such considerations provide an important background in evaluating the potential for proteoglycan metabolites, alongside other connective tissue metabolites, as biomarkers for assessing the deep-seated metabolic changes and as a diagnostic tool in monitoring orthodontic tooth movement.

Anti-metastatic efficacy and safety of MMI-166, a selective matrix metalloproteinase inhibitor

The anti-metastatic efficacy and safety of a newly-developed matrix metalloproteinase (MMP) inhibitor were examined. MMI-166, a N-sulfonylamino acid derivative, inhibited the enzyme activity of MMP-2, 9, and 14 but not MMP-1, 3 or 7. Daily oral administration of MMI-166 resulted in potent inhibition of metastatic lung colonization of Lewis lung carcinoma injected via the tail vein and liver metastasis of C-1H human colon cancer implanted into the spleen at inhibition levels of 43% and 63%, respectively. Daily administration of MMI-166 also resulted in prolonged survival of mice given intraperitoneal implantation of Ma44 human lung cancer cells. The anti-metastatic activity of MMI-166 was as effective as that of other MMP inhibitors with broad inhibitory spectrum. MMI-166 did not affect in vitro tumor cell growth. Neither body weight losses nor hematotoxicity was observed during long-term treatment, indicating the safety of MMI-166 in mice. These results indicate that the selective MMP inhibitor MMI-166 has therapeutic potential as an anti-metastasis agent.

Extracellular targeting of choline-binding proteins in Streptococcus pneumoniae by a zinc metalloprotease

A genetic-based search for surface proteins of Streptococcus pneumoniae involved in adhesion identified a putative zinc metalloprotease (ZmpB). ZmpB shared high amino acid sequence similarities with IgA1 proteases of Gram-positive bacteria, but ZmpB had neither IgA1 nor IgA2 protease activity. Analysis of a family of surface-expressed proteins, the choline-binding proteins (Cbp's), in a zmpB-deficient mutant demonstrated a global loss of surface expression of CbpA, CbpE, CbpF and CbpJ. CbpA was detected within the cytoplasm. The zmpB-deficient mutant also failed to lyse with penicillin, a sign of lack of function of the Cbp LytA. Immunodetection studies revealed that the autolysin (LytA), normally located on the cell wall, was trapped in the cytoplasm colocalized with DNA and the transformation protein CinA. Trafficking of CinA and RecA to the cell membrane during genetic competence was also not observed in the zmpB-deficient mutant. These results suggest a protease dependent regulatory mechanism governing the translocation of CinA and the Cbp's LytA and CbpA of S. pneumoniae.

Matrix metalloproteinase-19 in capillary endothelial cells: expression in acutely, but not in chronically, inflamed synovium

Matrix metalloproteinase-19 (MMP-19), originally isolated as an autoantigen from the synovium of a patient suffering from rheumatoid arthritis (RA), is expressed in smooth muscle cells of the tunica media of large blood vessels of an RA patient, but not in the endothelial cell layer. By contrast, in acutely inflamed tissue, synovial capillaries strongly express MMP-19 in the cytoplasm, as shown by immunofluorescence of cryostat sections. In MMP-19-producing capillaries the beta3 integrin chain was found at the endothelial cell surface, as was the vascular endothelial cell growth factor receptor-2 (KDR). The specific tissue inhibitor of metalloproteinases TIMP-1 was absent or faintly stained in MMP-19-expressing capillaries, whereas TIMP-1, but not TIMP-2, was strongly expressed in large vessels and in MMP-19-negative capillaries of RA synovia. In the spontaneously transformed human umbilical vein endothelial cell line ECV304 neither MMP-19 transcripts nor protein could be detected. By contrast, primary cultures of human endothelial cells of either dermal or adipose tissue origin produced MMP-19 mRNA and protein. The results strongly suggest the regulated induction of matrix metalloproteinase-19 in capillary endothelial cells during acute inflammation and hint at a role of MMP-19 in angiogenesis.

Spatiotemporal expression patterns of metalloproteinases and their inhibitors in the postnatal developing rat cerebellum

Matrix metalloproteinases (MMPs) are proteolytic enzymes that degrade the components of the extracellular matrix (ECM). The balance between MMPs and their inhibitors [tissue inhibitors of metalloproteinases (TIMPs)] in the pericellular environment determines the most significant proteolytic events in tissue remodeling. In vitro evidence is accumulating that these molecules may be crucial in the maturation of neural cells. Here, we investigated the in vivo expression of MMPs 2, 3, and 9 and TIMPs 1, 2, and 3 in the developing and adult rat cerebellum using immunohistochemistry and in situ hybridization. During postnatal development, all Purkinje (PK) cell somata expressed all the MMPs and TIMPs studied, whereas their growing dendritic trees expressed only MMP 3 and TIMP 3. In the adult, MMP 3 was confined to PK cell bodies, whereas TIMP 3 was expressed in PK cell somata and processes. Irrespective of the developmental stage, Bergmann glial processes contained only MMP 9, but their somata contained both TIMP 1 and MMP 9. In granular cells, MMPs 3 and 9 and TIMPs 1, 2, and 3 were chiefly detected at a time when migration is known to be maximal; except for that of TIMP 1, their expression persisted in the internal granular layer in the adult. The functional relevance of MMP expression was verified by gelatin zymography. MMP 9 activity was maximal on postnatal day 10 (P10) and was detectable at a low level on P15 and in the adult, whereas MMP 2 activity remained similar throughout postnatal development. Regional and cell-specific expression of MMPs and TIMPs closely reflects the successive stages of cerebellar development, thereby suggesting a pivotal role for ECM proteolysis in brain development and plasticity.

Extracellular matrix-driven matrix metalloproteinase production in endothelial cells: implications for angiogenesis

The process of new blood vessel growth, angiogenesis, involves orchestrated alterations in endothelial cell interactions with adjacent cells and with components of the underlying basement membrane matrix. The activity of matrix metalloproteinases (MMPs), proteases that can cleave basement membrane and interstitial matrix molecules, has been shown to be necessary for angiogenesis as it occurs in several different in vivo and in vitro models. This review discusses the potential roles of two particular MMPs, MMP-2 and MT1-MMP, in angiogenesis, with emphasis on current understanding of how endothelial cell-extracellular matrix interactions may regulate the production of these MMPs via matrix-induced signaling leading to transcriptional activation and subsequent formation of active multiprotease complexes on the cell surface.

A role for trigger factor and an rgg-like regulator in the transcription, secretion and processing of the cysteine proteinase of Streptococcus pyogenes

The ability of numerous microorganisms to cause disease relies upon the highly regulated expression of secreted proteinases. In this study, mutagenesis with a novel derivative of Tn4001 was used to identify genes required for the expression of the secreted cysteine proteinase (SCP) of the pathogenic Gram-positive bacterium Streptococcus pyogenes. Designated as Rop loci (regulation of proteinase), ropB is a rgg-like transcriptional activator required for transcription of the gene which encodes the proteinase. In contrast, ropA contributes post-transcriptionally to the secretion and processing of SCP and encodes a homologue of Trigger Factor, a peptidyl-prolyl isomerase and putative chaparone which is highly conserved in most bacterial species, but of unknown function. Analysis of additional ropA mutants demonstrated that RopA acts both to assist in targeting SCP to the secretory pathway and to promote the ability of the proprotein to establish an active conformation upon secretion. This latter function was dependent upon the peptidyl-prolyl isomerase domain of RopA and mutants that lacked this domain exhibited a bipartite deficiency manifested as a kinetic defect in autologous processing of the proprotein to the mature proteinase, and as a catalytic defect in the mature proteinase. These results provide insight into the function of Trigger Factor, the regulation of proteinase activity and the mechanism of secretion in Gram-positive bacteria.

Rodent pharmacokinetic and anti-tumor efficacy studies with a series of synthetic inhibitors of matrix metalloproteinases

Matrix metalloproteinases are a family of zinc-containing proteases that degrade extracellular matrix and basement membranes. These enzymes are thought to play a role in processes essential for tumor growth, invasion, and metastasis. Here we report pharmacokinetic and anti-tumor efficacy studies with a series of structurally related inhibitors of these enzymes that were synthesized at Agouron Pharmaceuticals using protein structure based drug design. The compounds studied were AG3287, AG3293, AG3294, AG3296, AG3319, and AG3340. Rat oral bioavailability ranged from 15 to 68%. Despite similar profiles of enzyme inhibition across the family of enzymes, and similar pharmacokinetics following i.p. administration to mice, efficacy against the Lewis lung carcinoma murine model varied from tumor growth enhancement, to significant reductions in the size of primary tumors and the number of lung metastases. AG3340 was the most efficacious compound against the Lewis lung carcinoma model, resulting in the complete cessation of primary tumor growth throughout the experiment in 4/6 mice treated with daily i.p. injections at a dose of 50 mg/kg. This treatment inhibited the formation of lung metastases greater than 5 mm in diameter by 90%.