Characterization of metalloproteinases and tissue inhibitors of metalloproteinases in human plasma

MMP-2 and MMP-9 in Human Peripheral Blood: Optimizing Gelatinase Calibrator for Degradome Research and Discovering a Novel Gelatinolytic Enzyme

Matrix metalloprotease-2 and -9 (gelatinase A and B, respectively) are enzymes crucially involved in a plethora of physiopathological conditions. Gelatin zymography is considered one of the major qualitative/semiquantitative assays for simultaneously determining zymogenic, active, and complexed forms of gelatinases. Critical steps are represented by variations in sample collection methods, molecular weight standard calibrators, and different zymography assay protocols. A normalization of these aspects is required for reducing discrepancies in technical procedures and interpreting results among different laboratories. In this study, we describe a novel protocol for gelatin zymography with increased pore size, which improves the separation of gelatinases with different molecular weights. A new method for obtaining gelatinase calibrator for gelatin zymography, by extracting MMP-2 and MMP-9 from peripheral blood, is also reported. Our method provides a gelatinase calibrator with enhanced stability both at room temperature and during multiple freeze-thaw cycles. This calibrator preparation is also suitable for in vitro post-translational modifications. For the first time, the improved zymography protocol allowed us to reveal in human peripheral blood samples new gelatinolytic bands resolved at very high molecular weight, likely complexes of MMP-9, undetectable with classical zymography protocols.

CD40 ligand shedding is regulated by interaction between matrix metalloproteinase-2 and platelet integrin alpha(IIb)beta(3)

BACKGROUND

CD40 ligand (CD40L, CD154) in the circulatory system is mainly contained in platelets, and surface-expressed CD40L on activated platelets is subsequently cleaved by proteolytic activity to generate soluble CD40L (sCD40L). However, the enzyme responsible for the shedding of CD40L in activated platelets has not been clearly identified yet. We have recently found that molecular interaction of matrix metalloproteinase-2 (MMP-2) with integrin alpha(IIb)beta(3) is required for the enhancement of platelet activation.

OBJECTIVES

To elucidate the biochemical mechanism of MMP-2-associated sCD40L release.

METHODS

Localization of MMP-2 and CD40L in platelets was analyzed by flow cytometry and fluorescence microscopy. The release of sCD40L from activated platelets was measured by enzyme-linked immunosorbent assay. MMP-2 binding to alpha(IIb)beta(3) was analyzed by immunoprecipitation and western blotting. Recombinant hemopexin-like domain and MMP-2-specific inhibitor were used to characterize the nature of MMP-2 binding and catalytic activity.

RESULTS

It was revealed that interaction of MMP-2 with alpha(IIb)beta(3) is required for effective production of sCD40L in activated human platelets. Platelet activation and release of sCD40L were significantly affected by inhibition of platelet-derived MMP-2 activity or by inhibition of binding between the enzyme and the integrin. It was also found in platelet-rich plasma that MMP-2 activity is responsible for generating sCD40L.

CONCLUSIONS

The results presented here strongly suggest that MMP-2 interacts with alpha(IIb)beta(3) to regulate the shedding of CD40L exposed on the surfaces of activated human platelets.

Matrix metalloproteinase-9: a novel biomarker for monitoring disease activity in patients with chronic urticaria patients?

BACKGROUND

Matrix metalloproteinase (MMP)-9, an enzyme that contributes to inflammatory responses and subsequent tissue remodelling, has recently been suggested to be a good biomarker for monitoring disease activity in patients with chronic urticaria (CU). Here, we assessed whether total MMP-9 and/or active MMP-9 plasma levels are increased and correlated to disease activity in patients with CU.

METHODS

Total MMP-9 and active MMP-9 plasma levels were determined by ELISA in 70 CU patients and control subjects (patients with psoriasis and healthy controls). CU activity was measured using weekly and daily composite symptom scores (urticaria activity score) calculated from the number of wheals and the intensity of pruritus.

RESULTS

Significantly increased levels of total and active MMP-9 were detected in patients with CU as compared to healthy controls. Interestingly, patients with psoriasis also had clearly elevated plasma levels of total and active MMP-9, indicating that MMP-9 plasma levels do not specifically reflect CU activity. Most notably, total and active MMP-9 levels were not correlated with disease activity in CU or psoriasis patients.

CONCLUSION

Plasma MMP-9 is not a good CU biomarker and should not be used for assessing the efficacy of treatment in CU patients or their spontaneous changes in disease activity.

ProMMP-2: TIMP-1 complexes identified in plasma of healthy individuals

Activation of MMPs in tissues is an important component of tissue injury. Based on earlier reports that (latent) proMMP-2 is incapable of forming a complex with TIMP-1, we reasoned that the identification of MMP-2:TIMP-1 complexes in blood might serve as a surrogate marker ("smoking gun") of MMP-2 activation in tissues. Using specific antibodies, we developed a sensitive and specific assay to detect MMP-2:TIMP-1 complexes. We were perplexed to find that approximate 40% of plasma specimens from healthy individuals had detectable levels of the MMP-2:TIMP-1 complexes. Employing recombinant TIMP-1 bound Sepharose beads and Western blots, we demonstrated binding between recombinant proMMP-2 and TIMP-1 proteins. Recombinant MMP-2 lacking the catalytic domain also bound to TIMP-1 coated beads. These data are consistent with TIMP-1 binding to the hemopexin or hinge domain of proMMP-2. The explanation for the presence of plasma proMMP-2:TIMP-1 complexes in selected healthy individuals remains to be determined. In contrast to our immunoassay and bead-binding experiments, proMMP-2 failed to bind to immobilized TIMP-1 employing surface plasmon resonance technology. Additional studies are needed to clarify these contrasting results.

Heparin affects matrix metalloproteinases and tissue inhibitors of metalloproteinases circulating in peripheral blood

OBJECTIVES

Blood sampling/handling alters matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) expression. The aim of this study is to evaluate the effects of high molecular weight heparin on MMP and TIMP expression in blood.

DESIGN AND METHODS

We analyzed by gelatin zymography and ELISA assays the effects of different heparin salts, dose- and time-dependence of MMP and TIMP concentrations in plasma and sera collected with and without clot-accelerator in plastic tubes from 50 healthy donors.

RESULTS

The levels and zymography of MMP-2 did not show significant changes among all samples, and during time- and dose-dependent heparin treatments. MMP-9 and TIMP-2 expression were strongly affected by heparin, with significant increase of their content and gelatinolytic activity both in time- and in dose-dependent fashion. Addition of heparin allowed also the displacement of MMP-2 prodomain, favouring zymogen activation.

CONCLUSIONS

Heparin has direct and indirect effects, altering MMP/TIMP complexes circulating in blood, and increasing the release of TIMP-2. To avoid misinterpretations due to MMP/TIMP complex alteration and MMP prodomain displacement, heparin should be cautiously used in blood collection procedures.

Purification of matrix metalloproteinases by column chromatography

Matrix metalloproteinases (MMPs) are zinc endopeptidases composed of 23 members in humans, which belong to a subfamily of the metzincin superfamily. They play important roles in many pathophysiological events including development, organogenesis, angiogenesis, tissue remodeling and destruction, and cancer cell proliferation and progression by degradation of extracellular matrix (ECM) and non-ECM proteins and interaction with various molecules. Here, we present standard protocols for purification of native proMMPs (proMMP-1, -2, -3, -7, -9 and -10) and recombinant MT1-MMP (MMP-14) using conventional column chromatography. Purification steps comprise the initial common step [diethylaminoethyl (DEAE)-cellulose, Green A Dyematrex gel and gelatin-Sepharose columns], the second step for removal of nontarget proMMPs by immunoaffinity columns (anti-MMP-1 and/or anti-MMP-3 IgG-Sepharose columns) and the final step for further purification (IgG-Sepharose, DEAE-cellulose, Zn2+-chelate-Sepharose and/or gel filtration columns). Purified proMMPs and MMP are functionally active and suitable for biochemical analyses. The basic protocol for the purification from culture media takes approximately 7-10 d.

Influence of blood sampling procedure on plasma concentrations of matrix metalloproteinases and their tissue inhibitors

1. Plasma levels of matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) are potential markers of many diseases involving extracellular matrix remodelling such as hypertension. Our aim was to determine whether the anticoagulant used to collect plasma and several freeze-thaw cycles may influence the accuracy of plasma MMP and TIMP determinations. 2. Plasma samples of 18 healthy volunteers were collected on three anticoagulants: heparinate, citrate and EDTA. For each anticoagulant, we compared: (i) MMP-2 and MMP-9 levels using gelatin zymography and TIMP-1 and TIMP-2 concentrations using enzyme-linked immunosorbent assay; (ii) intra- and interassay coefficients of variation (CV); and (iii) MMP and TIMP levels after up to five freeze-thaw cycles. 3. The choice of anticoagulant influenced TIMP-2 and TIMP-1 concentrations (TIMP-2, P < 0.0001; paired comparisons, citrate vs EDTA, P < 0.0001; EDTA vs heparin, P < 0.0001; citrate vs heparin, P < 0.0001; TIMP-1, P < 0.001; paired comparisons, citrate vs EDTA, P = 0.10; EDTA vs heparin, P < 0.01; citrate vs heparin, P < 0.0001), but not those of MMP. We observed a bias with heparinate for TIMP-2, TIMP-1 and MMP-9 determinations. The anticoagulant did not influence intra-assay or interassay CV. Performing freeze-thaw cycles led to alterations in the TIMP-1 plasma levels (P < 0.0001), regardless of the anticoagulant used, whereas MMP and TIMP-2 concentrations were not significantly affected. 4. Anticoagulant influences the measured levels of MMP and TIMP in plasma and should be systematically reported. However, it does not influence the reproducibility of the measurements. Repeated freeze-thaw cycles alter the measurement of TIMP-1 levels and should be avoided.

Differences in both matrix metalloproteinase 9 concentration and zymographic profile between plasma and serum with clot activators are due to the presence of amorphous silica or silicate salts in blood collection devices

Matrix metalloproteinases (MMPs) are promising diagnostic tools, and blood sampling/handling alters MMP concentrations between plasma and serum and between serum with and without clot activators. To explain the higher MMP-9 expression in serum collected with clot accelerators relative to serum with no additives and to plasma, we analyzed the effects of increasing amounts of silica and silicates (components of clot activators) in citrate plasma, serum, and buffy coats collected in both plastic and glass tubes from 50 healthy donors, and we analyzed the effects of silica and silicate on cultured leukemia cells. The levels of MMP-2 did not show significant changes between glass and plastic tubes, between serum and plasma, between serum with and without clot accelerators, or between silica and silicate treatments. No modification of MMP-9 expression was obtained by the addition of silica or silicate to previously separated plasma and serum. Increasing the amounts of nonsoluble silica and soluble silicate added to citrate and empty tubes prior to blood collection resulted in increasing levels of MMP-9 relative to citrate plasma and serum. Silica and silicate added to buffy coats and leukemia cells significantly induced MMP-9 release/secretion, demonstrating that both silica and silicate induce the release of pro- and complexed MMP-9 forms. We recommend limiting the misuse of serum and avoiding the interfering effects of clot activators.

Neutrophil activator of matrix metalloproteinase-2 (NAM)

We have isolated a novel soluble factor(s), neutrophil activator of matrix metalloproteinases (NAM), secreted by unstimulated normal human peripheral blood neutrophils that causes the activation of cell secreted promatrix metalloproteinase-2 (proMMP-2). Partially purified preparations of NAM have been isolated from the conditioned media of neutrophils employing gelatin-Sepharose chromatography and differential membrane filter centrifugation. NAM activity, as assessed by exposing primary human umbilical vein endothelial cells (HUVEC) or HT1080 cells to NAM followed by gelatin zymography, was seen within one hour. Tissue inhibitor of metalloproteinase-2 (TIMP-2) and hydroxamic acid derived inhibitors of MMPs (CT1746 and BB94) abrogated the activation of proMMP-2 by NAM, while inhibitors of serine and cysteine proteases showed no effect. NAM also produced an increase in TIMP-2 binding to HUVEC and HT1080 cell surfaces that was inhibited by TIMP-2, CT1746, and BB94. Time-dependent increases in MT1-MMP protein and mRNA were seen following the addition of NAM to cells. These data support a role for NAM in cancer dissemination.

Quantification of tissue inhibitor of metalloproteinases 2 in plasma from healthy donors and cancer patients

Tissue inhibitor of metalloproteinases (TIMP)-2 is a highly conserved molecule, which binds both active and latent matrix metalloproteinase (MMP)-2. TIMP-2 is also involved in the activation of MMP-2 on the cell surface. A quantitative enzyme-linked immunosorbent assay (ELISA) was established and optimized for measurement of TIMP-2 in plasma. The capturing antibody in the ELISA was a monoclonal, while the detecting antibody was a chicken polyclonal antibody recognizing the native form of human TIMP-2. The levels of TIMP-2 were measured in ethylenediaminetetraacetic acid (EDTA) and citrate plasma from healthy donors. The median values were determined as 163 ng/ml (n = 186) with a range of 109-253 ng/ml for EDTA plasma and 139 ng/ml (n = 77) with a range of 95-223 ng/ml for citrate plasma. The TIMP-2 concentration in citrate plasma from 15 patients with advanced, stage IV breast cancer had a median value of 160 ng/ml, only slightly higher but statistically distinguishable from the level found in citrate plasma from the healthy donors. In addition, the TIMP-2 concentration in EDTA plasma from colorectal cancer patients revealed a significantly higher level in plasma from patients with Dukes stage A (P = 0.01) compared with patients with more advanced Dukes stages.

The pro and the active form of matrix metalloproteinase-9 is increased in serum of patients with amyotrophic lateral sclerosis

Pro and active-matrix metalloproteinase-9 (MMP-9) was measured in sera from patients with amyotrophic lateral sclerosis (ALS), Guillain-Barre syndome (GBS), and healthy subjects. Both forms of MMP-9 were elevated in sera of ALS and GBS patients, compared with healthy controls. It has been postulated that elevated MMP-9 reflects damage to peripheral nerve and muscle. This possibility was investigated in sera, and tissue extracts of sciatic nerves and muscle from mice 5 and 12 days after axotomy of the sciatic nerve. Pro-MMP-9 was elevated in sera and extracts of damaged nerve and muscle, suggesting such damage may be followed by elevated pro-MM9-9 in sera. Active MMP-9 was only elevated in the sera. However, in situ activation of MMP-9 is tightly regulated and localised, and probably difficult to demonstrate by ELISA, resulting in a short half-life active MMP-9, implying any active MMP-9 in the serum may have a more immediate origin than injured muscle or nerve, for example circulating blood cells.

Tissue inhibitors of matrix metalloproteinases are elevated in cerebrospinal fluid of neurodegenerative diseases

Matrix metalloproteinases (MMPs) are implicated in the pathogenesis of diseases such as Alzheimer's Disease (AD) and amyotrophic lateral sclerosis (ALS). Increased expression of MMP-9 and TIMPs has been reported in postmortem AD and ALS brain tissue, as well as in ALS cerebrospinal fluid (CSF) and plasma. Although individual studies of MMP and TIMP expression in CSF have included AD and ALS samples, there are no studies comparing the expression of these proteins between neurodegenerative diseases. We measured the levels of matrix metalloproteinases (MMPs)-2 and -9 and the tissue inhibitor of MMPs (e.g. TIMP-1 and TIMP-2) in CSF samples from patients with Parkinson's Disease (PD), Huntington's Disease (HD), AD and ALS as compared to age-matched control patients. There was constitutive expression of the proform of gelatinase A (proMMP-2) on zymography gels in all CSF samples. Unexpectedly, there was an additional gelatinolytic band at 130 kDa of unknown etiology in the CSF samples of patients with PD (61% of patients studied), AD (61%), HD (25%) and ALS (39%). Levels of TIMP-1 were significantly elevated in CSF samples from all disease groups. TIMP-2 was significantly increased in CSF of AD and HD patients. MMP-2 levels did not differ significantly between groups. These findings show that TIMPs are elevated in the CSF of patients with neurodegenerative diseases suggesting a potential role of these endogenous inhibitors of matrix metalloproteinases in neurodegenerative diseases.

EMMPRIN-mediated MMP regulation in tumor and endothelial cells

Tumor invasion and metastasis are multistep processes which require extracellular matrix remodeling by proteolytic enzymes such as matrix metalloproteinases (MMPs). The production of these enzymes is stimulated by many soluble or cell-bound factors. Among these factors, extracellular matrix metalloproteinase inducer (EMMPRIN) is known to increase in vitro stromal cell production of MMP-1, MMP-2 and MMP-3. In this study, we demonstrated that EMMPRIN-transfected MDA-MB-436 tumor cells displayed a more invasive capacity than vector-transfected cells in a modified Boyden chamber invasion assay. Using gelatin zymography and protein analyses, we showed that EMMPRIN-transfected cancer cells produced significantly more latent and active MMP-2 and MMP-3 than vector-transfected cancer cells. We found that EMMPRIN did not regulate MMP-1, MMP-9, membrane type-1 MMP (MT1-MMP) expression and had also no effect on the production of the specific tissue inhibitors of MMPs (TIMPs), TIMP-1 and TIMP-2. We also demonstrated that tumor-derived EMMPRIN stimulated MMP-1, -2, and -3 without modification of MMP-9, MT1-MMP, TIMP-1 and TIMP-2 production in human umbilical vein endothelial cells (HUVEC). These data provide support for the role of EMMPRIN in tumor invasion, metastasis, and neoangiogenesis by stimulating extracellular matrix remodeling around tumor cell clusters, stroma, and blood vessels.

Role of gelatinase on follicular atresia in the bovine ovary

Follicular atresia, like follicular growth and ovulation, is characterized by excessive tissue remodeling. It is hypothesized that probably one of the tissue-remodeling enzymes, such as the gelatinases, could be playing an important role in this process. The present study was undertaken to determine the role of gelatinase on follicular atresia in the cow. Follicles of 2-6 mm in diameter were dissected from ovaries, and follicular fluid was categorized according to the morphological appearance of the cumulus-oocyte complexes. Gelatinase activity within the follicular fluid was analyzed by gelatin zymography, and film in situ zymography was employed in order to localize gelatinase. TUNEL was performed on cryosectioned ovaries to understand follicular health. The concentrations of steroids in follicular fluid were also measured by solid phase fluoroimmunoassay. ProMMP-2 was detected in all normal and atretic categories of follicular fluid. The active form of MMP-2 and an additional band of proMMP-9 were detected only in atretic follicular fluid. Gelatinase activity was recorded in both granulosa cells (GCs) and theca cells (TCs) but were found in comparatively higher numbers in those follicles that exhibited a thinned and partially detached granulosa layer. TUNEL confirmed that apoptosis had commenced in the GCs of follicles of the latter category. The estradiol-17beta (E(2)):progesterone (P(4)) ratio was found to be significantly lower in atretic follicles than in normal follicles. These results suggest a plausible role for gelatinase in follicular health, especially the active form of MMP-2 and proMMP-9, and that bovine follicular fluid may be a key indicator of atresia.

Host metalloproteinases in Lyme arthritis

OBJECTIVE

To assess the role of matrix metalloproteinases (MMPs) in cartilage and bone erosions in Lyme arthritis

METHODS

We examined synovial fluid from 10 patients with Lyme arthritis for the presence of MMP-2, MMP-3, MMP-9, and "aggrecanase" activity using gelatinolytic zymography and immunoblot analysis. We developed an in vitro model of Lyme arthritis using cartilage explants and observed changes in cartilage degradation in the presence of Borrelia burgdorferi and/or various protease inhibitors.

RESULTS

Synovial fluid from patients with Lyme arthritis was found to contain at least 3 MMPs: gelatinase A (MMP-2), stromelysin (MMP-3), and gelatinase B (MMP-9). In addition, there was evidence in 2 patients of "aggrecanase" activity not accounted for by the above enzymes. Infection of cartilage explants with B. burgdorferi resulted in induction of MMP-3, MMP-9, and "aggrecanase" activity. Increased induction of these enzymes by B. burgdorferi alone was not sufficient to cause cartilage destruction in the explants as measured by glycosaminoglycan (GAG) and hydroxyproline release. However, addition of plasminogen, which can act as an MMP activator, to cultures resulted in significant GAG and hydroxyproline release in the presence of B. burgdorferi. The MMP inhibitor batimastat significantly reduced the GAG release and completely inhibited the collagen degradation.

CONCLUSION

MMPs are found in synovial fluids from patients with Lyme arthritis and are induced from cartilage tissue by the presence of B. burgdorferi. Inhibition of MMP activity prevents B. burgdorferi-induced cartilage degradation in vitro.

Phase I and pharmacologic study of the specific matrix metalloproteinase inhibitor BAY 12-9566 on a protracted oral daily dosing schedule in patients with solid malignancies

PURPOSE

To evaluate the feasibility of administering BAY 12-9566, a matrix metalloproteinase (MMP) inhibitor with relative specificity against MMP-2, MMP-3, and MMP-9, on a protracted oral daily dosing schedule in patients with advanced solid malignancies. The study also sought to determine the principal toxicities of BAY 12-9566, whether plasma BAY 12-9566 steady state concentrations (C(ss)) of biologic relevance could be sustained for prolonged periods, and whether BAY 12-9566 affected plasma concentrations of MMP-2, MMP-9, and tissue inhibitor of MMP-2 (TIMP-2).

PATIENTS AND METHODS

Patients with solid malignancies were treated with BAY 12-9566 at daily oral doses ranging from 100 to 1,600 mg. BAY 12-9566 dose schedules included 100 mg once daily, 400 mg once daily, 400 mg twice daily, 400 mg three times daily, 400 mg four times daily, and 800 mg twice daily. Plasma was collected to study the range of BAY 12-9566 C(ss) values achieved, and exploratory studies were performed to assess the effects of BAY 12-9566 on plasma concentrations of MMP-2, MMP-9, and TIMP-2.

RESULTS

Twenty-one patients were treated with 47 28-day courses of BAY 12-9566. The most common side effects were headache, nausea, vomiting, abnormalities in hepatic functions, and thrombocytopenia, which were rarely clinically significant. BAY 12-9566 was well tolerated on all dose schedules, and there was no consistent dose-limiting toxicity that precluded treatment in the range of dose schedules evaluated. Instead, dose escalation was terminated because BAY 12-9566 plasma C(ss) values increased less than proportionately and plateaued as the daily dose was increased within the dose range of 100 to 1,600 mg/d, suggesting saturable drug absorption. Mean plasma C(ss) values achieved with all dose schedules exceeded BAY 12-9566 concentrations required to inhibit MMPs in vitro and in vascular invasion and tumor proliferation in vivo models. There were no consistent effects of BAY 12-9566 on the plasma concentrations of MMP-2 and MMP-9 over the continuous dosing period at any dose schedule level. However, plasma levels of TIMP-2 seemed to increase in a dose-dependent manner (r(2) =.50, P =.046).

CONCLUSIONS

The recommended dose of BAY 12-9566 for subsequent disease directed studies is 800 mg twice daily, which resulted in biologically relevant plasma C(ss) values and an acceptable toxicity profile. Although exploratory studies of MMPs in plasma were not revealing, it is conceivable that some tumor types and disease settings are more likely to produce more readily quantifiable levels of activated MMPs than others. Therefore, attempts to identify and quantify surrogate markers of MMP inhibitory effects should continue to be performed in disease-directed studies in more homogenous patient populations.

Borrelia burgdorferi induces matrix metalloproteinases by neural cultures

Matrix metalloproteinases (MMPs) are associated with chronic neurologic diseases such as multiple sclerosis and senile dementia. Lyme disease is a multisystemic infection involving the nervous system, skin, joints, and heart. Neurologic manifestations of chronic Lyme disease include encephalopathy and cranial and peripheral neuropathy. Borrelia burgdorferi, the spirochaete causing Lyme disease, has been cultured from the cerebrospinal fluid (CSF), and B. burgdorferi DNA is frequently detected in the CSF of patients with Lyme neuroborreliosis. We used cerebral and cerebellar primary cultures to determine whether B. burgdorferi induces the production of MMPs by primary neural cultures. B. burgdorferi in a dose- and time-dependent manner induced the expression of MMP-9 by primary neural cultures but had no effect on the expression of MMP-2. Human and rat type I astrocytes expressed MMP-9 when incubated with B. burgdorferi in the same manner as primary neural cultures. This response may play a role in the symptomatology and the pathogenesis of Lyme neuroborreliosis.

Regulation of gelatinases in human airway smooth muscle cells: mechanism of progelatinase A activation

Matrix metalloproteinases (MMPs) play an important role in tumor metastasis and invasion, inflammatory tissue destruction and remodeling, wound healing, and angiogenesis. The 72-kDa gelatinase A is the most widely distributed of all the MMPs, and along with the 92-kDa gelatinase B, both play an important role in the turnover of basement membrane. The role of MMPs in chronic airway inflammation and remodeling has received scant attention. In this study, we sought to examine the release and activation of gelatinases from human airway smooth muscle (ASM) cells and the effect of tumor necrosis factor-alpha and phorbol 12-myristate 13-acetate (PMA) on this release and activation. The role of membrane type 1 MMP (MT1-MMP) and tissue inhibitor of MMP (TIMP)-2 in activating progelatinase A has been explored. We have demonstrated, using human airway smooth muscle cells in culture, that 1) ASM releases gelatinase A constitutively and when stimulated with PMA and tumor necrosis factor-alpha releases gelatinase B, and the release of gelatinase B is protein kinase C dependent because it is blocked by H-7 and staurosporin; 2) treatment of ASM cells with PMA or concanavalin A failed to activate progelatinase A despite these agents increasing cell expression of MT1-MMP; and 3) the inability of ASM cell membranes to activate progelatinase A is most likely secondary to the high levels of TIMP-2 on the cell membrane. In conclusion, our results demonstrate that human ASM cells constitutively secrete progelatinase A and when stimulated with proinflammatory mediators secrete gelatinase B. The released gelatinases A and B may be important factors in the airway remodeling that occurs in asthma.

Mast Cell Expression of Gelatinases A and B Is Regulated by kit Ligand and TGF-β

Our prior work shows that cultured BR cells derived from dog mastocytomas secrete the 92-kDa proenzyme form of gelatinase B. We provided a possible link between mast cell activation and metalloproteinase-mediated matrix degradation by demonstrating that α-chymase, a serine protease released from secretory granules by degranulating mast cells, converts progelatinase B to an enzymatically active form. The current work shows that these cells also secrete gelatinase A. Furthermore, gelatinases A and B both colocalize to α-chymase-expressing cells of canine airway, suggesting that normal mast cells are a source of gelatinases in the lung. In BR cells, gelatinase B and α-chymase expression are regulated, whereas gelatinase A expression is constitutive. Progelatinase B mRNA and enzyme expression are strongly induced by the critical mast cell growth factor, kit ligand, which is produced by fibroblasts and other stromal cells. Induction of progelatinase B is blocked by U-73122, Ro31-8220, and thapsigargin, implicating phospholipase C, protein kinase C, and Ca2+, respectively, in the kit ligand effect. The profibrotic cytokine TGF-β virtually abolishes the gelatinase B mRNA signal and also attenuates kit ligand-mediated induction of gelatinase B expression, suggesting that an excess of TGF-β in inflamed or injured tissues may alter mast cell expression of gelatinase B, which is implicated in extracellular matrix degradation, angiogenesis, and apoptosis. In summary, these data provide the first evidence that normal mast cells express gelatinases A and B and suggest pathways by which their regulated expression by mast cells can influence matrix remodeling and fibrosis.

Quantitation of TIMP-1 in plasma of healthy blood donors and patients with advanced cancer

A kinetic enzyme-linked immunosorbent assay (ELISA) for plasma tissue inhibitor of metalloproteinase (TIMP)-1 was developed in order to examine the potential diagnostic and prognostic value of TIMP-1 measurements in cancer patients. The ELISA enabled specific detection of total TIMP-1 in EDTA, citrate and heparin plasma. The assay was rigorously tested and requirements of sensitivity, specificity, stability and good recovery were fulfilled. TIMP-1 levels measured in citrate plasma (mean 69.2+/-13.1 microg I(-1)) correlated with TIMP-1 measured in EDTA plasma (mean 73.5+/-14.2 microg I(-1)) from the same individuals in a set of 100 healthy blood donors (Spearman's rho = 0.62, P< 0.0001). The mean level of TIMP-1 in EDTA plasma from 143 patients with Dukes' stage D colorectal cancer was 240+/-145 microg I(-1) and a Mann-Whitney test demonstrated a highly significant difference between TIMP-1 levels in healthy blood donors and colorectal cancer patients (P < 0.0001). Similar findings were obtained for 19 patients with advanced breast cancer (mean 292+/-331 microg I(-1)). The results show that TIMP-1 is readily measured in plasma samples by ELISA and that increased levels of TIMP-1 are found in patients with advanced cancer. It is proposed that plasma measurements of TIMP-1 may have value in the management of cancer patients.

Modulation of plasma metalloproteinase-9 concentrations and peripheral blood monocyte mRNA levels in patients with septic shock: effect of fiber-immobilized polymyxin B treatment

The authors measured plasma metalloproteinase (MMP)-9 and corresponding monocyte mRNA in 20 patients with septic shock. Plasma MMP-9 concentrations and monocyte MMP-9 mRNA levels were significantly higher in the 10 nonsurviving patients with septic shock than in 10 surviving patients and 25 normal controls. Hemoperfusion using polymyxin B immobilized on fibers (PMX-F), a reportedly effective treatment for septic shock, was studied for effects on MMP-9 in the patients. Increases in plasma MMP-9 concentrations and corresponding monocyte mRNA levels were attenuated significantly by PMX-F treatment in both nonsurviving and surviving patients. These data suggest that plasma MMP-9 concentrations and monocyte MMP-9 mRNA levels may be useful prognostic markers in septic shock, and that PMX-F treatment affects MMP-9.

Specific matrix metalloproteinase profiles in the cerebrospinal fluid correlated with the presence of malignant astrocytomas, brain metastases, and carcinomatous meningitis

BACKGROUND

Detection in tumor tissue of specific matrix metalloproteinases (MMPs), particularly gelatinases A and B, correlates with the grade and aggressiveness of primary and metastatic brain tumors. The ability to detect these enzymes in the cerebrospinal fluid (CSF) would be a minimally invasive method of evaluating brain tumors.

METHODS

CSF from 66 patients with white blood cell counts of < or = 5 microL were analyzed for the presence of gelatinolytic activity by zymography. Twenty-nine patients had malignant astrocytomas, 10 had brain metastases from systemic malignancies, 4 had systemic cancer not involving the central nervous system, 4 had nonmalignant neurologic diseases, and 19 were healthy controls. Fifteen CSF samples had positive cytologies. The zymographic results were retrospectively correlated with clinical information and CSF cytologic data.

RESULTS

CSF from all patients with malignant astrocytomas or brain metastases contained precursor gelatinase A (pMMP2) and precursor gelatinase B (pMMP9), whereas control CSF contained only pMMP2. All patients with positive CSF cytologies had activated MMP2. A similar correlation was observed between the presence of activated MMP9 and positive CSF cytology.

CONCLUSIONS

The precursor and activated forms of gelatinases A and B can be detected in the CSF of patients with primary and metastatic brain tumors. The distribution of gelatinase activity in CSF distinguishes patients with malignant gliomas or brain metastases from those without brain tumors, and distinguishes patients with meningeal carcinomatosis from those without CSF spread of tumor, regardless of their brain tumor status. Analysis of MMPs in the CSF may be a sensitive technique for diagnosing CNS tumors and provide an early indication of tumor recurrence. This technique may also provide longitudinal information that would be useful in evaluating ongoing treatment and predicting tumor behavior.

Localization of TIMP-1, TIMP-2, TIMP-3, gelatinase A and gelatinase B in pathological human corneas

PURPOSE

Determine the tissue distribution patterns for tissue inhibitors of metalloproteinases (TIMP-1, TIMP-2, TIMP-3), gelatinase A and gelatinase B in normal and pathologic corneas.

METHODS

Corneas were examined by immunohistochemistry, using antibodies to TIMP-1, TIMP-2, TIMP-3, gelatinase A or gelatinase B.

RESULTS

In normal corneas, TIMP-1 antibody stained the epithelium and endothelium. TIMP-2 and TIMP-3 stained the epithelium, keratocytes and endothelium. Gelatinase A staining was weak and restricted to the epithelial cells. Radial keratotomy scars showed increased staining for TIMP-1 and TIMP-2 around the epithelial cell plug and along the incision. Bullous keratopathy corneas showed TIMP staining patterns similar to normal corneas and increased gelatinase A staining in regions of subepithelial fibrosis. Stromal scars of keratoconus corneas also had increased staining with TIMP-1 and TIMP-2 antibodies. In many keratoconus corneas, the TIMP-3 staining pattern was similar to normal corneas. However, in some keratoconus corneas, when Bowman's layer was missing, the stroma beneath was completely devoid of TIMP-3 antibody staining. No gelatinase B was seen in either the normal or diseased corneas.

CONCLUSION

These data suggest that TIMP-1 and TIMP-2 are important for scar formation and corneal remodeling, since they were found in increased amounts at radial keratotomy incision sites and keratoconus scars. The significance of the focal stromal defects in TIMP-3 staining, associated with absence of Bowman's layer on keratoconus corneas, needs to be elucidated. At the stages of disease examined in this study, gelatinase B may not play a significant role in these pathological processes, since it was not seen in any of the corneas examined.

Role of the matrixin MMP-2 in multicellular organization of adipocytes cultured in basement membrane components

Primary rat adipocytes cultured in basement membrane component gels migrated and organized into large, three-dimensional, multicellular clusters. Gross morphological changes seen during this reorganization are described. The rate of cluster formation decreased with age of the rats and was stimulated by insulin in older, but not in younger rats. Echistatin, a disintegrin, partially inhibited the formation of multicellular clusters in a concentration-dependent fashion (50% inhibitory concentration approximately 10 nM). The original extracellular matrix was initially remodeled and eventually destroyed by the time large multicellular clusters were observed. This implied that one or more matrix-degrading protease(s) were being secreted. Adipocyte-conditioned medium was found to contain a divalent cation-sensitive gelatinase activity at approximately 72 and/or approximately 62 kDa. The elution profile of this activity from gelatin-Sepharose 4B was similar to matrix metalloproteinase 2 (MMP-2, a 72-kDa matrixin with a 62-kDa mature form), and the dimethyl sulfoxide eluant from these columns contained MMP-2 immunoreactivity. MMP-2 concentration and activity were greater in conditioned medium from young than from older animals; however, insulin did not affect the amount of MMP-2 in adipocyte-conditioned media. The matrixin inhibitor 1,10-phenanthroline not only blocked gelatinase activity in zymograms but also prevented extracellular matrix remodeling and destruction, as well as adipocyte migration and the formation of cell-cell contacts in adipocyte cultures. These observations are consistent with the hypothesis that the matrixin MMP-2 is secreted by adipocytes. Whereas matrixin activity alone may not be sufficient for the formation of multicellular clusters, the data indicate that it may have a requisite role in this process.

Oncostatin M differentially regulates tissue inhibitors of metalloproteinases TIMP-1 and TIMP-3 gene expression in human synovial lining cells

Tissue inhibitor of metalloproteinases (TIMP) 1, 2 and 3 are related proteins that can form complexes with all known matrix metalloproteinases (MMPs). They inhibit the action of MMPs on extracellular matrix components. The balance of MMPs and TIMPs is important for tissue remodeling and its disturbance is believed to play a crucial role in pathophysiological processes such as tumor metastasis, destruction of cartilage and fibrosis. Cytokines and growth factors were found to regulate TIMPs and MMPs in a complex manner. In order to better understand the role of TIMPs in inflammatory joint diseases we have studied in vitro the regulation of TIMP-1 and TIMP-3 by inflammatory cytokines in cultured human synovial lining cells. We found that transforming growth factor beta 1 as well as interleukin-1 beta induce gene expression of both TIMP-1 and TIMP-3. In contrast, oncostatin M, an interleukin-6-type cytokine produced by activated T-lymphocytes and monocytes, had a differential effect on TIMP mRNA levels. After oncostatin M treatment, TIMP-1 expression was up-regulated but basal, as well as interleukin-1 beta-induced, TIMP-3 expression was inhibited. Interleukin-6 itself had no effect on synovial lining cells but a complex of interleukin-6 and the soluble interleukin-6 receptor induced activation of signal transducer and activator of transcription (STAT) factors in these cells and regulated TIMP-1 and TIMP-3 expression in a similar fashion as oncostatin M. Since TIMP-3 is matrix-associated whereas TIMP-1 is found in many body fluids, the role of oncostatin M during inflammatory processes might be to promote ECM degradation in the local environment but to prevent it systemically.

Elastase-induced matrix degradation in arterial organ cultures: an in vitro model of aneurysmal disease

PURPOSE

Abdominal aortic aneurysms are characterized by degradation of the extracellular matrix, induction of endogenous metalloproteinases (MMPs), and development of a chronic inflammatory infiltrate. Despite intensive analysis of end-stage tissue, aneurysm pathogenesis remains obscure. The aim of this study was to develop an in vitro model of aneurysmal disease.

METHODS

Porcine aortic organ cultures were preincubated with pancreatic elastase before culture in standard conditions for up to 14 days. The extent of matrix degradation at various time points was determined by quantitative histologic estimation of collagen and elastin concentration. Endogenous metalloproteinase production within the tissue was quantified by gel enzymography and immunoblotting. A separate series of experiments was performed to investigate the effect of incorporating autologous leukocytes into the culture system.

RESULTS

Although exogenous elastase was removed after 24 hours, substantial degradation of the aortic extracellular matrix occurred in the subsequent 13 days in tissue culture. Analysis of samples preincubated with elastase (100 U/ml) for 24 hours before tissue culture demonstrated that elastin degradation occurred in a time-dependent manner (p < 0.001) and was not confined to the initial phase of exogenous elastase activity. Gelatin gel enzymography revealed a time-related production of metalloproteinases (55 to 250 kDa) within the aortic tissue. The presence of MMPs-1, 2, 3, and 9 was determined by immunoblotting. Immunohistochemistry identified the vascular smooth-muscle cell as the source of MMPs-1, 2, and 3. Addition of autogenous leukocytes to elastase-pretreated tissue initiated an inflammatory infiltrate within the aortic wall, which further enhanced both matrix degradation and MMP production (p < 0.001).

CONCLUSIONS

These data demonstrate that aortic samples pretreated with elastase before tissue culture undergo matrix degradation with MMP production and the development of an inflammatory infiltrate. These changes mirror the pathophysiological events within established aneurysms. It is suggested that this model may be useful in understanding early pathogenic events within aneurysmal tissue.

Activated forms of MMP2 and MMP9 in abdominal aortic aneurysms

PURPOSE

This consistent observation of a reduction of the elastin concentration in abdominal aortic aneurysms (AAAs) has led us to investigate in AAA specimens two metalloproteinases that display elastase activity, MMP2 (gelatinase A/72kDa) and MMP9 (gelatinase B/92 kDa).

METHODS

Samples of full-thickness aortic wall, adherent thrombus, and serum were collected in 10 patients with AAAs. Samples of normal aortic wall and serum were taken from 6 age-matched control patients. Quantitative gelatin-zymography and gelatinolytic soluble assays after acetyl-phenyl mercuric acid activation were performed on serum and tissue extracts, and the results were expressed in units on a comparative wet-weight basis. Histologic analysis was performed in parallel to score the inflammatory infiltrate.

RESULTS

The luminal and parietal parts of the thrombus contained, respectively, 20- and 10-fold more gelantinolytic activity than the serum. The predominate form was MMP9. Although the total gelatinolytic activity was in the same range both in AAAs and in normal walls, a significantly higher proportion of MMP9 was found in the aneurysmal aortic walls. Furthermore, a significant proportion of MMP9 was under its processed active form, which was never observed in normal samples. A significantly higher proportion of MMP2 was also present as processed active form in AAA wall. This latter parameter positively correlated with the inflammatory score.

CONCLUSIONS

The presence of activated MMP9 and MMP2 might contribute to the degradation of the extracellular matrix proteins that occurs during the development of aneurysms.

Stimulation of collagenase (matrix metalloproteinase-1) synthesis in histiotypic epithelial cell culture by heparin is enhanced by keratinocyte growth factor

The role of heparin and heparan sulfate in the control of epithelial collagenase production was investigated utilizing a histiotypic cell culture model. The effect of keratinocyte growth factor (KGF), a heparin-binding growth factor, on collagenase secretion was also examined. Heparin, and, to a lesser extent, heparan sulfate induced release of a 58-kDa, gelatin-degrading enzyme which was subsequently identified as the collagenase, matrix metalloproteinase-1. The increase in collagenase secretion by heparin was further enhanced by the addition of KGF. KGF alone did not have any effect. Analysis of secreted radiolabelled proteins showed that the increase in collagenase activity was not due to a general increase in protein synthesis. Synthesis of collagenase protein was specifically increased by heparin and further increased by KGF plus heparin. Heparin and heparan sulfate in combination with KGF may thus have important roles in the regulation of epithelial cell collagenase under conditions such as inflammation and wound healing.

Matrix metalloproteinases and their tissue inhibitors in endocrinology

Matrix metalloproteinases (MMPs) and their natural inhibitors (TIMPs) have been widely implicated in tissue resorption, degradation, and fibrosis in a range of normal and abnormal processes, but recently defined additional actions suggest much broader and independent roles for different members of these gene families. This review examines the involvement of hormones in regulation of MMPs and TIMPs and focuses on known and potential roles of particular interest to endocrinologists.

Expression of a biologically active murine tissue inhibitor of metalloproteinases-1 (TIMP-1) in baculovirus-infected insect cells. Purification and tissue distribution in the rat

Murine tissue inhibitor of metalloproteinases-1 (mTIMP-1) was expressed in baculovirus-infected insect cells (Sf9). The protein secreted into the culture medium was purified to homogeneity by means of heparin-Sepharose CL-6B and FPLC. The purified protein showed metalloproteinase-inhibitory activity in two independent assays: reverse zymography and inhibition of collagenase activity. Digestion of the recombinant TIMP-1 with peptide-N-glycanaseF revealed that both N-glycosylation sites are used. 125I-mTIMP-1 intraveneously injected into a male Sprague Dawley rat disappeared within 2 min from the circulation. 5 min after injection more than 50% of the 125I-mTIMP-1 were found in the liver and 20% in the kidneys. At later times, trichloroacetic-acid-soluble material accumulated in the intestinal tract.

Thrombin induces the activation of progelatinase A in vascular endothelial cells. Physiologic regulation of angiogenesis

Angiogenesis requires degradation of vascular basement membrane prior to migration and proliferation of endothelial cells; proteinases are essential ingredients in this process. Because of thrombin's multiple effects on endothelium, we have examined its role in matrix metalloproteinase activation using human umbilical vein endothelial cells. Gelatin zymography of endothelial conditioned media revealed a prominent 72-kDa progelatinase A band. Addition of alpha-thrombin to endothelial cells resulted in the generation of 64 and 62 kDa gelatinolytic bands which is consistent with the activation of progelatinase A; thrombin had no effect in the absence of cells. This effect requires the proteolytic site of thrombin since progelatinase A activation was abolished by specific inhibitors of thrombin. Matrix metaloproteinase inhibitors diminished thrombin-induced activation of progelatinase A. Pretreatment of endothelial cells with excess tissue inhibitor of metalloproteinase-2 or a COOH-terminal fragment of progelatinase A abrogated thrombin-mediated activation of progelatinase A presumably by competing with the COOH terminus of native progelatinase A for interaction with an activator site on endothelial plasma membranes. Although membrane-type matrix metalloproteinase was demonstrated in endothelial cells by Northern and Western blotting, the receptor function of this molecule in thrombin-induced activation of progelatinase A needs to be clarified. Progelatinase A activation did not require intracellular signal transduction events mediated by the thrombin receptor. These data demonstrate that 1) endothelial cells express a novel activation mechanism for progelatinase A, 2) proteolytically active thrombin regulates this activation mechanism, and 3) activation occurs independently of the functional thrombin receptor.

Plasma assay of gelatinase B: tissue inhibitor of metalloproteinase complexes in cancer

BACKGROUND

Matrix metalloproteinases (MMPs), especially gelatinase A and gelatinase B (GLB), are believed to be important components of the metastatic process. Tissue Inhibitors of Metalloproteinases (TIMPs) form complexes with MMPs and inhibit cancer dissemination. After local secretion, MMPs and their complexes with TIMPs leach into the blood stream where their concentration can be measured, thereby serving as surrogate markers of disease. Elevated plasma gelatinase B levels have been detected in gastrointestinal cancer and breast cancer. The goal of this study was to determine whether plasma GLB:TIMP complexes also are increased in cancer and whether these tests have potential use as prognostic tumor markers.

METHODS

An enzyme-linked immunosorbent assay (ELISA) was developed to measure the plasma concentration of GLB:TIMP complexes in patients with cancer. Correlation between ELISA results and clinical outcome was sought.

RESULTS

Plasma GLB:TIMP complexes were significantly increased in patients with gastrointestinal cancer and gynecologic cancer, but not in patients with breast cancer. When results from plasma GLB:TIMP complexes and plasma GLB assays were combined (GLB/complexes), abnormal levels of one or both assays were found in 36% and 65% of patients with gastrointestinal and gynecologic cancer, respectively. In Stage IV gastrointestinal cancer, patient survival was shorter (P < 0.001) in the group with increased plasma GLB/complexes than for those with normal plasma levels (4 months vs. 20 months, respectively).

CONCLUSIONS

The assay of plasma gelatinase B and GLB:TIMP complexes may be clinically useful in predicting survival in subsets of patients with cancer. The possibility of using these assays in early stage cancer to predict metastasis should be studied.

Keratinocyte growth factor stimulation of gelatinase (matrix metalloproteinase-9) and plasminogen activator in histiotypic epithelial cell culture

The purpose of this investigation was to examine the role that keratinocyte growth factor (KGF) plays in the control of matrix-degrading protease activity in epithelial cells. The culture conditions had a significant effect on cellular responses to the growth factor. In histiotypic culture on porous-polycarbonate membranes, porcine periodontal ligament epithelial cells responded to KGF with increased 92-kDa gelatinase (matrix metalloproteinase [MMP]-9) activity. No such response was observed in cells maintained on plastic plates. Epidermal growth factor and platelet-derived growth factor also increased MMP-9 activity in the histiotypic cultures of epithelial cells. Addition of heparin with KGF produced a further increase in MMP-9 activity, with heparin alone having no effect. Precoating of polycarbonate membranes with matrix components showed that fibronectin and an engineered poly-RGD molecule substrate were required for KGF plus heparin to increase MMP-9 activity. Precoating plastic culture plates with the same proteins did not generate the same response. Concomitant with gelatinase activity, KGF also increased urokinase-type plasminogen activator in the epithelial cells. Thus, KGF appears to be an important regulator of protease secretion in epithelial cells.

Neutrophil gelatinase levels in plasma and synovial fluid of patients with rheumatic diseases

To examine the clinical significance of neutrophil gelatinase in rheumatic diseases, plasma and synovial fluid (SF) gelatinase levels were determined in 62 patients with rheumatoid arthritis (RA), 12 patients with ankylosing spondylitis (AS), 18 patients with osteoarthritis (OA) and 17 healthy controls. The gelatinase level was measured by enzyme-linked immunoassay (ELISA). The assay had a sensitivity of 1 ng/ml and a working range of 5-25 ng/ml. Gelatinase levels were significantly higher in the plasma of patients with RA and of patients with RA complicated by amyloidosis or vasculitis as compared to those of healthy controls. Moreover, the mean value of gelatinase in the plasma of patients with RA complicated by vasculitis was found to be significantly higher than that of RA patients without vasculitis. A significant increase in gelatinase concentration was also observed in the plasma of AS patients but not in the plasma of patients with OA. The concentration of gelatinase in the RA SF samples was much higher (18-fold) than the level of the enzyme in the plasma of RA patients. There was also a higher concentration of gelatinase (four-fold) in OA SF compared with OA plasma. The results suggested that circulating gelatinase may reflect some degree of neutrophil activation in patients with inflammatory arthritis, especially in those with RA complicated by vasculitis. However, the results did not allow a differentiation between chronic and acute inflammation.

Tissue inhibitor of metalloproteinases-2 (TIMP-2) in rat liver cells is increased by lipopolysaccharide and prostaglandin E2

To explore the functional role of TIMP-2 in liver, we determined TIMP-2 mRNA levels in primary rat hepatocytes and in total rat liver. Rat hepatocytes constitutively express TIMP-2 mRNA at a low level. Incubation with dexamethasone, prostaglandin E2 and a combination of inflammatory cytokines leads to an up-regulation of TIMP-2 mRNA. In rats in vivo we found a dramatic increase of TIMP-2 expression after intraperitoneal injection of lipopolysaccharide. Compared to our previous findings on TIMP-1 we conclude that TIMP-2 mRNA expression is regulated in a distinct and partially opposite manner. Over-production of TIMP-2 could inhibit the activity of metalloproteinases and thus lead to matrix accumulation. Dysregulation of TIMP-2 synthesis might be involved in the development of liver fibrosis.

Matrix-degrading proteases in hormone-dependent breast cancer

Proteases have emerged as important modulators of the metastatic capacity of cancer. However, metastasis is regulated by multiple other characteristics of the tumor cell and evidence suggests the participation of multiple classes of proteases. In the present article we review the literature concerning the potential biological roles of multiple proteases in breast cancer. In particular, we focus on the gelatin-degrading metallo proteinase and on a novel 80 KDa matrix-degrading protease that appears to be commonly expressed in hormone dependent breast cancer cell lines.

Comparison of techniques for measurement of gelatinases/type IV collagenases: enzyme-linked immunoassays versus substrate degradation assays

Radiolabeled substrate degradation assays and gelatin zymography are routinely employed to assay 72 kDa gelatinase A (MMP-2) and 92 kDa gelatinase B (MMP-9) in biological fluids. Enzyme-linked immunosorbent assays (ELISA) have recently been developed for the quantitation of these matrix metalloproteinases (MMP). In this study, we have compared ELISA to standard substrate degradation assays for measurement of MMP-2 and MMP-9 in human plasma and tumor-conditioned media. Gelatin Sepharose chromatography and gel filtration chromatography were employed as partial purification procedures for MMP-2 and MMP-9. The ELISA data for MMP-2 and MMP-9 are linear on a log:log regression curve over a wide range of MMP concentrations and are specific for the designated gelatinase, with no overlap detected with related metalloproteinases. The minimum detectable concentrations of MMP-2 and MMP-9 were approximately 0.5 ng/ml and 0.2 ng/ml, respectively, in the ELISA as compared to 4 ng/ml and 3 ng/ml, respectively, in gelatin zymography. The [3H]gelatin degradation assay required a combination of > 50 ng/ml of MMP-2 and MMP-9 for detection. Although gelatin zymography was less sensitive than ELISA (primarily due to the smaller sample volume employed) and was more difficult to quantitate, this procedure offers the important advantage of being able to distinguish between latent and activated gelatinases.