Trophoblast cell-mediated modifications to uterine spiral arteries during early gestation in the macaque

A specialized subset of invasive embryonic cytotrophoblast cells gains access to maternal uterine arteries early in the gestation of higher primates. These cells continue to migrate extensively within the lumina of spiral arteries, converting them to the highly modified uteroplacental arteries of pregnancy. Although trophoblast cell-mediated modifications are considered critical to the progress of normal pregnancy, few studies have addressed the cellular interactions between maternal arteries and embryonic cells in situ. Macaque placentas and endometrial tissues were collected from 12 animals from day 14 of gestation (blastocyst implantation begins on day 9) to day 49. Standard indirect immunoperoxidase methods were used to identify matrix metalloproteinases (MMP-1, MMP-3, MMP-9), cathepsin B, cathepsin D, platelet-endothelial cell adhesion molecule, cytokeratins, smooth muscle actin, CD68, and factor VIII-related antigen. Cytotrophoblast cells were located deep within spiral arteries in each of the specimens examined. In some examples tightly packed clusters of cytotrophoblast occluded the lumina of invaded arteries. Initial penetration of arterial tunica intima was revealed by discontinuities in the staining pattern for factor VIII and cytotrophoblast intrusion was indicated by cytokeratin staining of the trophoblast cells. Continued cytotrophoblast intrusion into the tunica media was apparent by gaps in the smooth muscle. MMP-1, MMP-3, and MMP-9 were localized within intraluminal and intramural cytotrophoblast. By contrast, neither cathepsin B nor cathepsin D were present, although both were seen in uterine macrophages and stromal cells. Upon reaching the surrounding uterine stroma the cytotrophoblast cells ceased migration. As cytotrophoblast accumulated in the arterial wall the vascular lumen expanded. Evidence of cell death was rarely encountered in associated maternal or embryonic tissues. We conclude that intra-arterial cytotrophoblast cells express several proteinases with substrate specificities sufficient to permit independent remodeling of the extracellular matrix comprising uterine artery walls. The remodeling of the arteries, which involves extensive displacement of maternal endothelium and smooth muscle, in addition to degradation and synthesis of extracellular matrix, is accomplished with little evidence of cell death or loss of the integrity of the arteries. This process provides an interesting example of cooperation between different types of interacting tissues from genetically distinct individuals.

An immunocytochemical study for lysosomal cathepsins B and D related to the intracellular degradation of titanium at the bone-titanium interface

The morphological relationship between titanium and lysosomal proteinases, cathepsins B and D, at the bone-titanium interface using titanium-coated plastic implants placed for 28 days in the tibiae of 6-week-old rats was immunocytochemically investigated by the colloidal immunogold-silver method. Under light microscopy the titanium layer appeared to make direct contact with the bone and one or a few layers of slender cells were interposed between the bone and titanium. Ultrastructurally, the titanium came in contact with the bone or the slender cell layer through a 20 to 40 nm thin amorphous zone. The slender cells at the bone-titanium interface consisted of two types; one was an osteoblast type with glycogen granules which was found along the newly-formed bone facing titanium layer. The other was a fibroblast type which came in contact with the titanium layer and occasionally endocytosed the detached titanium fragments. In addition, some of the slender cells also showed degenerative changes. Immunocytochemically, cathepsins B and/or D were sometimes colocalized in some phagolysosomes with titanium fragments. These findings suggested that the fibroblast types at the bone-titanium interface may act as scavengers to remove both cell debris and titanium by means of some endocytotic ability, and lysosomal cathepsins also developed in response to the endocytosed titanium. The osteoblast type also appears to show a high degree of osteogenic activity around the titanium-coated plastic implants.

Cathepsin B, alpha2-macroglobulin and cystatin levels in gingival crevicular fluid from chronic periodontitis patients

Gingival crevicular fluid (GCF) was collected from 16 molar and premolar sites in each of 20 chronic periodontitis patients before and after periodontal therapy using filter paper strips. These were eluted individually into buffer for determination of cathepsin B and its endogenous inhibitors, alpha2-macroglobulin and cystatin. Cathepsin B activity was assayed with a fluorogenic peptide substrate, alpha2-macroglobulin by enzyme-linked immunosorbent assay and cystatin activity by inhibition of papain. Total amounts of enzyme and inhibitor per GCF sample decreased after treatment and correlated positively with pocket depth and gingival, bleeding and plaque indices. These comparisons were nearly always statistically significant for pooled site data and sometimes so for mean patient values. The amounts of alpha2-macroglobulin and cystatin were greater than those of cathepsin B and, surprisingly, enzyme and inhibitor levels correlated positively with each other. Experiments with purified reagents, however, demonstrated that the cathepsin B: alpha2-macroglobulin complex was still active against the low molecular weight substrate and that cystatin levels in GCF are probably insufficient to inhibit the enzyme substantially These factors may explain why GCF cathepsin B activity reflects the clinical status of periodontal lesions and has been identified in another study as a promising indicator of disease progression.

Localization of procollagen I in the lysosome/endosome system of human fibroblasts

A significant amount of newly synthesized collagen is degraded intracellularly rather than secreted, but there is controversy about whether this process occurs in the lysosomes. We addressed this problem using confocal microscopy and immunofluorescence imaging to study the distribution of procollagen I in the Golgi and the lysosome/endosome system of cultured human fibroblasts. Cells were incubated under basal conditions and then permeabilized and exposed to fluorescently tagged probes for procollagen, Golgi markers (Helix pomatia binding protein or beta-coatamer protein), and lysosome/endosome markers (cathepsin B or LAMP-2). Strong signals for procollagen codistributed with the Golgi and lysosome/endosome markers. Of note, many structures were positive for procollagen and lysosome/endosome markers but not for Golgi markers. When cells were incubated with the proline analog cis-hydroxyproline, which inhibits correct triple helix formation and increases intracellular degradation, the amount of procollagen codistributing with the lysosome/endosome markers increased greatly. Similar results were obtained in I-cells, which do not have functioning lysosomal hydrolases. These findings strongly indicate that the lysosome/endosome system participates in the intracellular degradation of newly synthesized procollagen and that trafficking of procollagen to the lysosome/endosome system does not depend on the cells having active lysosomal hydrolases. We present a model that integrates our findings with other work and resolves inconsistencies in the literature. This model postulates the existence of three separate degradation paths for newly synthesized procollagen. In addition to the endosome/lysosome system, degradation also takes place in the proximal region of the secretory pathway such as the endoplasmic reticulum, cis-Golgi network, or cis-Golgi and in a distal region of the secretory pathway such as the trans-Golgi or trans-Golgi network.

Involvement of interleukin-6 in activation of lysosomal cathepsin and atrophy of muscle fibers induced by intramuscular injection of turpentine oil in mice

Serum IL-6 level increased after the injection of turpentine oil into the right gastrocnemius muscle in mice. The mRNA level of IL-6 was highest in the injected muscle at 12 h after injection, but was not identified in the opposite muscle. The activities of cathepsins B and B+L started to elevate after 12 h in the injected muscle and markedly increased after day 3. Likewise, the mRNA levels of cathepsins B and L markedly increased from day 1 to day 5 in the injected muscle. However, a very mild increase was also observed in the opposite muscle. Immunohistochemical staining of cathepsins B and L exhibited positive reactions as fine granules in myofibers at 12 h and strong positive reactions in the infiltrating macrophages at 3 days. Atrophy of myofibers type 1 and 2 was evident in a time-dependent manner in the injected muscle. Treatment with rat anti-mouse IL-6 receptor monoclonal antibody inhibited the increase in cathepsin activities in the injected muscle. We conclude that IL-6 produced in the inflamed muscle is involved in the process of muscle degeneration, especially through the activation of lysosomal cathepsins.

Selective induction of the secretion of cathepsins B and L by cytokines in synovial fibroblast-like cells

We have investigated the potent influence of some cytokines, tumour necrosis factor-alpha (TNF-alpha), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF) and interferon-gamma (IFN-gamma), on the secretion of cysteine proteinases (cathepsins B and L) by cultured synovial fibroblast-like cells from patients with rheumatoid arthritis (RA). After treatment of synovial fibroblast-like cells with cytokines, culture media were evaluated for cathepsins B and L by enzyme immunoassays, and for cathepsin B and L activities using the enzymatic substrates. Z-Phe-Arg-AMC and Z-Arg-Arg-AMC, and specific inhibitors. Treatment of synovial fibroblast-like cells with TNF-alpha or PDGF resulted in a marked increase in cathepsin B secretion. Moreover, after prolonged PDGF treatment, the amount of secreted cathepsin B returned to the low control level. In contrast, bFGF led to increased cathepsin L secretion. IFN-gamma induced both cathepsin B and L secretion. Our results show that cytokines induce a selective secretion of cathepsins B and L by synovial fibroblast-like cells. This selective effect of cytokines on the secretion of cysteine proteinases suggests that synovial fibroblast-like cell-mediated articular degradation is a highly regulated process.

Use of enzyme overlay membranes to survey proteinase activity in frozen sections: cathepsin-like and plasmin-like activity in regenerating newt limbs

We present a method that permits extremely simple and rapid screening of proteolytic enzyme activity in sectioned tissues. Enzyme overlay membranes (EOMs) are custom-made membranes designed to fluoresce at sites of specific proteolytic enzyme activity after separation of proteins by gel electrophoresis. EOMs, selected to detect either plasmin-like or cathepsin B-like activity, have been used in a novel way to document the distribution of enzyme activity in frozen sectioned tissues. When moistened membranes were placed in contact with sectioned regenerating newt limbs, a fluorescent pattern of enzyme activity was generated. In limbs at 3 hr post amputation, cathepsin B-like activity was prominent across the amputation site but plasmin-like activity was distributed in dermal and deeper proximal tissues, suggesting different roles for these two classes of enzymes. EOM enzymology in situ (EEI) on frozen sectioned tissues may be a widely useful technique to display distribution and level of activity of proteolytic enzymes in various systems.

Laminin and cathepsin B as prognostic factors in stage I non-small cell lung cancer: are they useful?

Laminin, a glycoprotein component of basement membrane, and cathepsin B, a lysosome-derived proteinase, are thought to play a role in the complex process of tumor invasion and metastasis. This study evaluates the possible prognostic significance of laminin degradation and cathepsin B expression in Stage I (T1NO, T2NO) human non-small cell lung cancer. Archival, formalin-fixed, paraffin-embedded lung tissue from patients with documented Stage I non-small cell cancer was studied in a series of 31 patients (14 men, 17 women; ages 40-82 yr; mean age, 67 yr) by using polyclonal antibodies against laminin and cathepsin B. The immunoexpression of laminin was assessed with respect to a continuous versus discontinuous pattern, whereas that of cathepsin B was semiquantitated according to a four-tiered grading scale: 0, 0% positive cells; 1, 1 to 9%; 2, 10 to 49%; and 3, more than 50% positive cells. Cox proportional hazards models and Kaplan-Meler survival analysis were used to evaluate the association of possible risk factors, including laminin and cathepsin B, with survival. Univariate analysis looking at possible associations of survival with age, sex, histologic type, degree of tumor differentiation, and tumoral stage (T1NO, T2NO) did not show significant association. Likewise, degradation of laminin and immunoexpression of cathepsin B did not show significant association with survival. Although previous studies suggested improved survival with increased laminin expression and decreased survival with high expression of cathepsin B, the results applying to intrastage (Stage I) non-small cell cancer suggest that the expression of laminin and cathepsin B has little prognostic significance.

Investigations into the cellular contribution to host tissue proteases and inhibitors in gingival crevicular fluid

Gingival crevicular fluid (GCF) was collected from chronic periodontitis patients using plastic micropipettes and coverslip smears stained with antibodies for leukocyte markers and Toluidine Blue for mast cells. The smears consisted of 70-80% granulocytes, 10-20% monocytes/macrophages, 5% mast cells and 5% T lymphocytes; no B lymphocytes were found. Proteases and inhibitors in GCF cells were investigated by enzyme cytochemistry using 2-methoxy-4-naphthylamine-linked peptide substrates and simultaneous coupling to Fast Blue B and immunocytochemistry using biotinylated secondary antibodies and an alkaline phosphatase/new fuchsin detecting system. Elastase was detected in granulocytes, cathepsin B in macrophages, dipeptidyl peptidases II and IV in a small proportion of macrophages, dipeptidyl peptidase IV in a few T lymphocytes, tryptase in mast cells and alpha-1-proteinase inhibitor and alpha-2-macroglobulin in some macrophages. GCF was also collected on filter paper strips and eluted into buffer for biochemical enzyme assays. Lysis of cells by addition of detergent to the elution buffer increased activities to 140-240% of control values. Removal of cells by centrifugation reduced measured activities to 1-30% of original figures; this effect was less if samples were pre-treated with detergent. Proteases from inflammatory cells therefore appear to make up most of the measured enzyme activity in GCF, and this association may explain recent correlations with periodontal disease progression.

The cysteine proteinases of Schistosoma mansoni cercariae

Based on substrate preferences, cercariae of Schistosoma mansoni were seen to express both cathepsin L and cathepsin B cysteine proteinases, although the former activity was many-fold greater. Two cathepsin L activities identified in cercarial extracts by zymography co-migrated with activities in extracts of 3 h and 24 h schistosomula and in extracts of adult worms. Since these enzymes have been implicated in haemoglobin digestion by adult worms, they may perform a similar function in schistosomula. Immunolocalization using scanning electron micrographs showed that cathepsin L and cathepsin B proteinases were present in the cercarial post-acetabular glands. In addition, cercarial serine proteinase activities considered to facilitate skin penetration efficiently cleaved the substrates Z-Gly-Pro-Arg-NHMec and Z-Gly-Pro-Lys-NHMec. Cercariae release most of this serine proteinase activity when induced to secrete the contents of their acetabular glands. In contrast, newly transformed 3 h and 24 h schistosomula did not express this activity.

Prognostic value of cathepsins B, D and steffins A and B in laryngeal carcinoma

Concentrations of cathepsins A, D and stefins A and B were measured in primary tumor and adjacent normal tissue of 25 patients with laryngeal carcinoma. Median concentrations of both cathepsins and that of stefin B were significantly higher in tumor tissue than in their normal counterparts (cathepsins B and D, P < 0.0001; stefin B, P = 0.01), indicating their possible involvement in the process of tumor spread. Early (T1 and T2) tumors had lower concentrations of stefins A and B than locally advanced (T3 and T4) tumors (P = 0.04). Disease-free and disease-specific survival rates at 45 months were significantly better in patients with tumor concentrations of stefins above or equal to the cut-off values (stefin A, P = 0.001 and P = 0.004; stefin B, P = 0.048 and P = 0.008), indicating that these might be of prognostic value. The concentrations of cathepsins B and D did not correlate with survival.

Calpain and cathepsins in the skeletal muscle of inflammatory myopathies

To clarify the significance of intracellular lysosomal (cathepsins B, L and H) and extralysosomal (calpain) proteolytic systems in the process of muscle fiber degradation in inflammatory myopathies, biopsied muscle specimens were examined from patients with polymyositis (PM) and dermatomyositis (DM). Generally, in specimens from patients with PM and DM, but not in those from normal controls, muscle fibers surrounding inflammatory infiltrates or in the perifascicular regions, and occasionally mononuclear cell infiltrates demonstrated positive immunostaining for calpain and cathepsins B, L, and H. In addition, enzyme activities of cathepsins B and L increased in specimens with inflammatory myopathy. These results suggest that calpain and cathepsins play a significant role in the process of muscle fiber destruction in inflammatory myopathy.

Processing of cathepsins L, B and D in psoriatic epidermis

Proteinase activity is increased in psoriatic epidermis. To elucidate the involvement of enzymes in psoriatic epidermis, the expression of cathepsins, L, B and D was investigated by Western blotting and immunohistological studies. Normal epidermis contained abundant inactive precursors (39 kDa) of cathepsins L and B and an inactive intermediate form (45 kDa) of cathepsin D. Cathepsin L in psoriasis was processed to a variable extent from the precursor to a single-chain form (30 kDa) and a mixture of single- and heavy-chain (25 kDa) forms of the active mature enzyme, corresponding to the immunohistological staining patterns 'diffuse dense', 'small granular', and unevenly distributed 'condensed granular'. Cathepsin B showed a mixture of precursor form (39 kDa) and single-chain (30 kDa) forms and was expressed as a 'diffuse dense' staining pattern in the mid-spinous layer and as a 'condensed' pattern in the upper spinous and granular layers. Cathepsin D was processed to the heavy-chain (31 kDa) form of activated mature enzyme with small granular staining and a mixture of heavy-chain and degraded protein (28 kDa) with larger and more condensed granular staining. The distribution patterns of 'small granular' cathepsin L, and of cathepsins B and D expression in suprabasal keratinocytes were very similar to that of involucrin. After complete clinical resolution of psoriasis by 8-methoxypsoralen plus UVA treatment, the expression of the three cathepsins was normalized. These results suggest that cathepsins L, B and D in forms activated to a variable extent may be involved in the pathology of psoriasis.

Increased levels of cathepsin B and L, urokinase-type plasminogen activator and its inhibitor type-1 as an early event in gastric carcinogenesis

BACKGROUND

Cysteine proteases [cathepsin B (CATB), cathepsin L (CATL)], the serine protease urokinase-type plasminogen activator (UPA) and its inhibitor type-1 (PAI-1) play an important part in cancer invasion. No data are available on the relationship between these proteases and gastric precancerous changes.

AIMS

To determine CATB, CATL, UPA, PAI-1 in chronic atrophic gastritis, intestinal metaplasia and gastric epithelial dysplasia, as precancerous changes, and to compare these data with those obtained in gastric cancer.

PATIENTS

Endoscopic biopsies were obtained from 12 patients with gastric cancer (cancerous tissue), 33 patients with chronic atrophic gastritis (all with intestinal metaplasia and 12 with dysplasia) and from 47 control subjects, for a total of 92 patients.

METHODS

Antigen concentrations were measured using ELISA methods. Immunohistochemistry was performed using monoclonal anti-CATB and anti-PAI-1 antibodies.

RESULTS

CATB, CATL, UPA and PAI-1 were significantly higher in chronic atrophic gastritis than in controls (CATB: P < 0.001; CATL: P < 0.005; UPA: P < 0.000001; PAI-1: P < 0.005). The same was observed for cancer. CATB and UPA were significantly higher in chronic atrophic gastritis, with versus without dysplasia (P < 0.05). Dysplastic epithelia showed strong immunoreactivity to PAI-1 and CATB.

CONCLUSIONS

Our study demonstrates that cathepsins, UPA and PAI-1 may have a role not only in the process of cancer invasion, but also in the progression of precancerous changes into cancer.

Immunolocalization of the cation-independent mannose 6-phosphate receptor and cathepsin B in the enamel organ and alveolar bone of the rat incisor

In order to examine our hypothesis that maturation ameloblasts could degrade the enamel matrix in a manner analogous to bone resorption mediated by osteoclasts, we have assessed the distribution of lysosomal enzymes in the enamel organ by immunolocalizing the cation-in-independent mannose 6-phosphate receptor (MPR) and the lysosomal enzyme cathepsin B at all stages of amelogenesis. Secretory ameloblasts showed strong immunoreactivity for MPR in the supranuclear Golgi region and in the cytoplasm between the Golgi region and the distal junctional complexes. However, cathepsin B immunoreactivity was mainly seen in the distal portion of Tomes' process, which was unreactive for MPR immunogenicity. In maturation ameloblasts, the MPR was observed on the ruffled border of the ruffle-ended ameloblast (RA) but not on the distal cell membrane of the smooth-ended ameloblast (SA), although both cell types demonstrated strong immunoreactivity for MPR in the Golgi region. Immunoreactive cathepsin B was seen at the distal ends of both RA and SA. It is postulated that the nascent lysosomal enzymes bind to the mannose 6-phosphate receptors which target them not only to intracellular lysosomes, but also to the ruffled border of maturation ameloblasts where these enzymes are secreted into the enamel. Since MPR and lysosomal enzymes were also detected on the ruffled border of osteoclasts (Ocl) adjacent to alveolar bone, our immunocytochemical approach provides strong evidence for a similarity between the maturation process in enamel, as mediated by the ruffle-ended maturation ameloblasts, and bone resorption mediated by osteoclasts. This study has established that a common mechanism, based on MPR-targeted lysosomal secretion and matrix degradation, is basic to the maturation process involved in calcified tissues as different as bone and enamel.

Differential secretion of cathepsins B and L from normal and tumor human lung cells stimulated by 12(S)-hydroxy-eicosatetraenoic acid

Cathepsins B and L play roles in intracellular and extracellular proteolysis in normal and malignant processes. A directed extracellular proteolysis by regulated secretion could facilitate the process of invasion. We have therefore investigated the effect of the physiological signal mediator 12(S)-hydroxy-eicosatetraenoic acid on the release of cathepsins B and L in normal and malignant human lung cells. Quantitative determinations of cathepsin activities were done by flow cytometry and spectrofluorometry using synthetic dipeptidyl substrates coupled to fluorogens. Most interestingly, a difference in the secretion of cathepsins B and L was found: only release of active cathepsin B was detected. The effect was specific for 12(S)-hydroxy-eicosatetraenoic acid, 12(R)-hydroxy-eicosatetraenoic acid, and 5(S)-hydroxy-eicosatetraenoic acid were ineffective. The response was immediate but a substantial amount of nonreleasable activity remained cell bound. Alveolar macrophages, Wi-38 fibroblasts, and tumor cells derived from large cell carcinomas and adenocarcinomas were sensitive to 12(S)-hydroxy-eicosatetraenoic acid, but cells from undifferentiated squamous cell carcinomas were not. Sensitivity did not parallel malignancy but more likely the degree of differentiation of cells. The investigated tumor cell lines showed no detectable endogenous 12-lipoxy-genase activity to synthesize 12(S)-hydroxy-eicosatetraenoic acid from arachidonate; therefore, we assume a paracrine mechanism for 12(S)-hydroxy-eicosatetraenoic acid action. Protein kinase C alpha, a key enzyme involved in 12(S)-hydroxy-eicosatetraenoic acid-elicited responses, was expressed in all sensitive tumor cells, but insignificantly in a sensitive normal cell line and an insensitive tumor cell line. From our experiments we propose two separate intracellular pools of active cathepsin B: an unreleasable, lysosomal fraction and a fraction available for regulated secretion. Different processing and sorting mechanisms may be responsible for the generation of these cathepsin B-fractions in these pools.

[Cathepsin B-like substance in the monitoring of chemically induced primary cholangiocarcinoma in swine]

Activity of beta-glucuronidase (GL), placentar izoenzyme of alkaline phosphatase (PLAP), cathepsin B (CB) and concentrations of carcinoembryonic antigen (CEA) were determined in serums and bile of pigs with experimental cholangiocarcinoma and in control animals. No differences in serum GL, PLAP, CB activities or CEA were observed. The same was found in bile for GL, PLAP and CEA. However, in bile the situation was different for CB. In all the tumour bearing animals we were able to demonstrate in the course of tumour development a stricking progression in CB activity. Very impressive was namely an elevation of CB alkaline-stable form, generated (according also to the chromatographic studies of the bile) from primary cholangiocarcinoma tissue.

1,25-Dihydroxyvitamin D3 induces morphological and biochemical markers of apoptosis in MCF-7 breast cancer cells

1,25-Dihydroxyvitamin D3 [1,25(OH)2(D)3], the active metabolite of vitamin D, is a potent inhibitor of breast cancer cell growth both in vivo and in vitro. To complement data which documents the anti-proliferative effects of 1,25(OH)2(D)3, we assessed the role of apoptosis in vitamin D-mediated growth arrest of MCF-7 cells. Time course studies indicated that 100 nM 1,25(OH)2(D)3 significantly reduces MCF-7 cell numbers within 48 h of treatment. Morphological assessment demonstrated that MCF-7 cells treated with 1,25(OH)2(D)3 for 48 h exhibit characteristic apoptotic features, including cytoplasmic condensation, pyknotic nuclei, condensed chromatin and nuclear matrix re-organization. In situ end labelling with terminal transferase indicated that cells exhibiting apoptotic morphology in 1,25(OH)2(D)3-treated cultures were positive for DNA strand breaks. These morphological features of apoptosis were accompanied by an increase in the cell death rate assessed as soluble DNA-histone complexes indicative of DNA fragmentation. To complement the morphological data, we assessed the temporal expression of two proteins which have been associated with apoptosis in mammary cells and tumors. The steady state mRNA levels for TRPM-2/clusterin and cathepsin B mRNA were significantly up-regulated in MCF-7 cells treated with 1,25(OH)2(D)3 compared to control cells. Time-dependent increases in the expression of TRPM-2/clusterin and cathepsin B proteins were detected by Western blotting in 1,25(OH)2(D)3-treated cells. These findings indicate that, in addition to its anti-proliferative effects, 1,25(OH)2(D)3 activates the apoptotic cell death pathway in MCF-7 breast cancer cells.

Cathepsin B in gingival crevicular fluid of adult periodontitis patients: identification by immunological and enzymological methods

Cathepsin B (EC 3.4.22.1), a typical lysosomal cysteine proteinase was identified immunologically with anti-human cathepsin B antibody in inflammatory exudate, gingival crevicular fluid (GCF) of adult periodontitis patients. The sensitive enzyme immunoassay (EIA) system initially developed, was rarely influenced by the presence of endogenous cysteine proteinase inhibitors, cystatin(s), indicating that it is possible to quantify the gross amount of cathepsin B including free enzyme forms and enzyme-inhibitor complex forms using this EIA system. The cathepsin B levels in GCF as determined by EIA and the activity measured with Z-Arg-Arg-MCA showed positive and significant correlation with various clinical parameters. Immunoblotting analysis revealed that the molecular form was a 29 kDa mature enzyme. More than 95% of Z-Arg-Arg-MCA hydrolytic activity in each GCF sample was inhibited by CA-074, specific inhibitor of cathepsin B. These results strongly suggested that the gross amount of cathepsin B in GCF as well as its activity level is closely associated with the severity of the disease and that cathepsins B play an important role in the pathogenesis of periodontitis.

The thiol enzyme from rat spleen that produces bradykinin potentiating peptide from rat plasma

We have focused our studies on a thiol-dependent enzyme of 37 kilodaltons (kDa) that produces a bradykinin (BK) potentiating peptide. The molecular mass of the peptide was estimated to be around 750 Da and its amino acid composition was Pro4 Gly2 Leu1 Ser1 with a proline and a serine at the N- and C-terminals, respectively. Biological activity was assayed by means of uterus contraction. The enzyme differs from Cathepsin L or B by virtue of its immunological reactivity and enzyme kinetics. The inhibitors used were leupeptin, antipain, E-64 and chymostatin in order of effectiveness. The low molecular SH reagents also diminished the enzyme activity. Among the metal ions tested, Cu2+ and Zn2+ inhibited the reaction.

A comparison of cysteine and serine proteinases in human gingival crevicular fluid with tissue, saliva and bacterial enzymes by analytical isoelectric focusing

Gingival crevicular fluid (GCF) contains several different proteinase activities and the study sought to clarify their sources. Gingival tissue and GCF were collected from chronic periodontitis patients. Gel-filtration chromatography of crude tissue extracts yielded cathepsin B and tryptase fractions sensitive to cysteine and serine proteinase inhibitors, respectively. Cell sonicates of suspected periodontal pathogens were prepared from broth cultures of reference strains. Of these, Porphyromonas gingivalis showed much the strongest activity and this had an effector response consistent with the metal-dependent cysteine proteinase described by others. Banding patterns in GCF, tissue and bacterial samples were compared on substrate-impregnated overlay membranes applied to isoelectric focusing gels. On Z-Val-Lys-Lys-Arg-AFC overlays, GCF had bands corresponding to tissue cathepsin B and the enzyme from P. gingivalis, though a contribution from Treponema denticola could not be ruled out. Use of D-Val-Leu-Arg-AFC overlays showed GCF activity similar to tissue tryptase. In GCF there were additional bands that did not correspond to any tissue or bacterial samples and on Z-Ala-Ala-Lys-AFC overlays these closely resembled activity in parotid saliva. The results confirmed that GCF contains tissue cathepsin B and tryptase, while the apparent presence of enzymes from P. gingivalis and possibly T. denticola is consistent with previous reports linking activity to these organisms. The saliva bands demonstrated that contamination of GCF may occur despite rigorous collection procedures.

The use of substrates with 7-amino-3-trifluoromethylcoumarine (AFC) leaving group in the localization of protease activities in situ

A method for the localization of activities of proteases using substrates with 7-amino-3-trifluoromethylcoumarine (AFC) leaving group is described. 0.1 ml of 5-20 mMol solution of the respective substrate (Gly-Pro-AFC, Ala-Pro-AFC, Z-Ala-Arg-Arg-AFC, Z-Gly-Arg-Arg-AFC, Z-Gly-Gly-Arg-AFC, D-Val-Leu-Lys-AFC) in dimethylsulfoxide or dimethylformamide was added to 0.9 ml of 0.1 M Tris-HCl buffer, pH 7.4-7.8 or 0.1 M cacodylate buffer, pH 5-5.5. In the case of Z-Ala-Arg-Arg-AFC (cathepsin B substrate) 15 mM EDTA and 12 mM dithiothreitol were added. 7 mM amiloride or 2 mg/1 ml aprotinin were used as inhibitors with Z-Gly-Gly-Arg-AFC (urokinase substrate) and with D-Val-Leu-Lys-AFC (plasmin substrate). Substrate solutions were mixed with an equal amount of 2% agar solution in distilled water or in the respective buffer the pH of which was adjusted according to the pH optimum of the enzyme to be demonstrated. The agar solution was kept in a water bath at a temperature of 50-60 degrees C. After careful mixing, the substrate solution in agar was poured into a cylindrical vessel closed with a semipermeable membrane (Nephrophan) on which unfixed cryostat sections were mounted. 1-5 mM AFC solution in dimethylsulfoxide or dimethylformamide instead of the substrate was used as the control. Quenched samples of rat kidney and jejunum, biopsies of human jejunal mucosa, and of colorectal and uterine tumors were employed for the preparation of sections. After gelification of the medium in a refrigerator the vessels with sections were incubated in the dark at 37 degrees C for 0.5-several h. The reaction was controlled in a fluorescence microscope with an epiillumination adjusted to the FITC fluorescence and documented. A yellowish green fluorescence depicts sites where AFC was set free (sites with enzyme activity). When the reaction reached the required intensity the membranes were cut off, transferred to glass slides, mounted in glycerol, observed and photographed immediately (due to the solubility of AFC in glycerol). An acceptable cellular localization was achieved. The method with AFC substrates can be recommended for comparative biochemical and histochemical studies of proteases using the same substrate and for cases in which no other reliable procedure for the localization of the respective enzyme activity is available (e.g. urokinase, plasmin).

Tumor progression and angiogenesis: cathepsin B & Co

Experimental and clinical evidence reveals that the growth of solid tumors is dependent on angiogenesis. Proteolytic enzymes such as plasminogen activators and matrix metalloproteinases have been implicated in this neovascularization. The role of lysosomal proteases in this process has yet to be explored. Increased expression of the lysosomal cysteine protease cathepsin B has been observed in many etiologically different tumors, including human brain, prostate, breast, and gastrointestinal cancers. Immunohistochemical and in situ histochemical studies have demonstrated expression of cathepsin B in neovessels induced during malignant progression of human glioblastoma and prostate carcinomas. In these two tumor types, neovessels stain strongly for cathepsin B compared with the normal microvasculature. As an initial point to elucidate whether cathepsin B is an important component of the angiogenic response in tumours, we analyzed expression of cathepsin B in endothelial cells during neovessel formation. We present evidence for strong immunostaining of cathepsin B in rat brain microvascular endothelial cells as they form capillary tubes in vitro. This finding is discussed within the general framework of the role of proteolytic enzymes in tumor invasion and angiogenesis.

Interleukin 6 receptor antibody inhibits muscle atrophy and modulates proteolytic systems in interleukin 6 transgenic mice

The muscles of IL-6 transgenic mice suffer from atrophy. Experiments were carried out on these transgenic mice to elucidate activation of proteolytic systems in the gastrocnemius muscles and blockage of this activation by treatment with the anti-mouse IL-6 receptor (mIL-6R) antibody. Muscle atrophy observed in 16-wk-old transgenic mice was completely blocked by treatment with the mIL-6R antibody. In association with muscle atrophy, enzymatic activities and mRNA levels of cathepsins (B and L) and mRNA levels of ubiquitins (poly- and mono-ubiquitins) increased, whereas the mRNA level of muscle-specific calpain (calpain 3) decreased. All these changes were completely eliminated by treatment with the mIL-6R antibody. This IL-6 receptor antibody could, therefore, be effective against muscle wasting in sepsis and cancer cachexia, where IL-6 plays an important role.

Physical association of Ras and cathepsins B and L in the conditioned medium of v-Ha-ras-transformed NIH3T3 cells

Immunoblot analysis of the conditioned medium of v-Ha-ras-transformed NIH3T3 cells showed that Ras protein is secreted in the culture fluid. Because cathepsins L and B whose activities are inhibited by Ras are also secreted, possible association between Ras and cathepsins was investigated by immunoprecipitation and following immunoblot analysis. The results showed that Ras is physically associated with cathepsins B and L in the culture fluid.

Cathepsin B, L, and D activities in colorectal carcinomas: relationship with clinico-pathological parameters

Cathepsins, which are secreted by tumour and/or stromal cells, are thought to be involved in the degradative processes of tumour invasion and metastasis. The purpose of our study was to compare the cytosolic content of cathepsin B, L, and D in a series of matched malignant and adjacent normal colorectal tissues. Further we attempted to correlate these different proteinase values to classical clinico-pathological prognostic variables. Cathepsin B, L, and D activities were higher in tumour tissues than in normal mucosa (P < 10(-6), P < 0.004, P < 0.004, respectively) with median tumour/normal ratios of 7.9, 5.9, and 1.4, respectively. We found no difference in cathepsin B, L, and D activities either as a function of gender (except for cathepsin B values), age at time of surgery, tumour site, tumour differentiation, tumour stage (TNM or Astler-Coller staging system) or whether or not we found a mucinous component. Based on our data, cathepsin B seems to be the most discriminant parameter of the three proteinases that we studied, suggesting that cathepsin B expression may be of critical value in the progression of colorectal cancers.

[A study on cathepsin B-like substance in cancer of the urinary tract]

Cathepsin B, a cysteine proteinase, has been shown to be increased in tumor tissue and to be responsible for the process of invasion and metastasis. To study the biochemical characteristics of cathepsin B-like substance in the tissue of a non-cancerous kidney and some urologic cancer tissues, we extracted cathepsin B-like substances from a non-cancerous human kidney tissue, human renal tumor, human renal pelvic tumor and human bladder tumor. The cathepsin B-like substance extracted from the non-neoplastic human kidney has a molecular weight of approximately 28,000. On the result of western blotting with anti-human liver cathepsin B antibody, two types of protein were observed in the fraction extracted from urologic cancer tissues. The molecular weights of them were 28,000 and 35,000, respectively. Both types of cathepsin B-like substances had the same activities for benzyloxy-carbonyl-L-arginine-L-arginine-4-methyl-7-coumarylamide, and both activities were inhibited by (L-3-transcarboxyoxiran-2-carbonyl)-L-leucyl-agmatin. These findings suggest that both cancer cells of the renal parenchyma and urothelium secrete cathepsin B-like protease which express not only a normal cathepsin B but also a higher molecular weight of cathepsin B-like protease and that a higher one plays an important role in a process of invasion.

Avian cathepsin B cDNA: sequence and demonstration that mRNAs of two sizes are produced in cell types producing large quantities of the enzyme

Overlapping cDNA fragments encoding avian cathepsin B were cloned from an osteoclast cDNA library and sequenced. The primary structure of the prepro enzyme deduced from this sequence has 340 amino acids. The mature portion of the enzyme is 80% identical with murine cathepsin B; regions found in other papain superfamily enzymes are conserved. In osteoclasts and cultured macrophages, which produce large quantities of cathepsin B, mRNAs of 1.8 and 2.4 kb are produced in approximately equal quantities, while cells producing smaller quantities of the enzyme produce predominantly the 2.4 kb form. This variation in mRNAs suggests transcriptional differences related to production of large quantities of the enzyme.

Cysteine and serine proteases in gastric cancer

BACKGROUND

Cysteine proteases (cathepsin B [CATB] and cathepsin L [CATL]), the serine protease urokinase-type plasminogen activator (UPA), and plasminogen activator inhibitor type-1 (PAI-1) are thought to play an important part in cancer invasion and metastasis. The aims of this study were to measure CATB, CATL, UPA, and PAI-1 in gastric cancer (GC) and normal mucosa distant from the tumor (NORM); to evaluate whether tissue levels are related to tumor stage, grade, or histotype; to assess their prognostic relevance; and to examine UPA and PAI-1 expression immunohistochemically.

METHODS

Gastric cancer and NORM samples were obtained from 25 patients with gastric cancer patients undergoing surgery (17 males, 8 females; mean age, 62 years; range, 31-84 years). Antigen concentrations were measured using the enzyme-linked immunosorbent assay method. Immunohistochemistry was performed using monoclonal UPA and PAI-1 antibodies.

RESULTS

Significantly higher antigen levels were found: (1) in GC vs. NORM (CATB, CATL, UPA, PAI-1) tissues; (2) in GC with versus without metastasis (CATB, CATL, UPA); (3) in poorly or moderately versus well differentiated GC; and (4) in diffuse versus intestinal-type GC (CATB, CATL). Urokinase-type plasminogen activator, PAI-1 and CATB levels had a significant prognostic impact. Cancer and stromal cells, showed immunoreactivity to anti-UPA and anti-PAI-1 antibodies.

CONCLUSIONS

These results confirm the important role of CATB, CATL, UPA and PAI-1 in gastric cancer progression. Higher levels are detected in GC with metastases, poorer differentiation, and diffuse histotype, thus identifying patients with a worse prognosis.

Immunolocalization of cathepsin B in human glioma: implications for tumor invasion and angiogenesis

The poor prognosis of patients with malignant gliomas is at least partially due to the invasive nature of these tumors. In this study, the authors investigated the possibility that the cysteine protease cathepsin B (CB) is a participant in the process of glial tumor cell invasion. To accomplish this, an immunohistochemical analysis was made of the localization of antibodies to CB in biopsies of five specimens of normal brain, 16 astrocytomas, 33 anaplastic astrocytomas, and 33 glioblastomas multiforme. Staining was scored according to the percentage of positive cells and the intensity of the stain, graded from 0 to 3+. Staining for CB was not seen in any of five samples of normal brain except for occasional neuronal cell bodies and microglia. Only five (31%) of 16 astrocytomas showed a small percentage of positive cells (0.01%-3%) that were stained in a light, diffuse cytoplasmic pattern (1+). Twenty-nine (87.8%) of 33 anaplastic astrocytomas showed positive light, granular staining in 2% to 40% of cells. In anaplastic astrocytoma, the staining within a tumor was heterogeneous with intensities of 1+ (17%), 1+ to 2+ (29%), or 2+ (55%). In contrast, all 33 (100%) glioblastomas were positive in 10% to 90% of cells. The staining was present in a coarse, granular pattern with an intensity of 2+ (12%) or 3+ (88%). Tumor cells infiltrating into brain adjacent to malignant gliomas stained positively in 26 cases that could be evaluated for glioblastoma multiforme; these invading cells frequently followed penetrating blood vessels as typical "secondary structures of Scherer." Moderate to intense CB staining associated with endothelial proliferation in high-grade tumors was also observed, especially in regions of tumor infiltration into adjacent normal brain. These results provide evidence consistent with the hypothesis that CB is functionally significant in the process of tumor invasion and angiogenesis in the clinical progression of the malignant phenotype in astrocytes.

Prognostic value of the cysteine proteases cathepsins B and cathepsin L in human breast cancer

The lysosomal cysteine proteases cathepsin B and cathepsin L have been implicated in tumor spread and metastasis. To evaluate the prognostic impact of these proteases for disease-free survival and overall survival in breast cancer, the antigen content of cathepsin B and cathepsin L was determined using ELISA in tumor cytosol fractions of 167 breast cancer patients and in cytosols of 29 benign breast tissue specimens. Median values of 856 ng versus 76 ng cathepsin B/mg protein and of 428 ng versus 56 ng cathepsin L/mg protein were found in tumor versus benign cytosol fractions. A positive correlation between cathepsin B and cathepsin L (r = 0.32, P = 0.0000, Spearman test) was found. Cathepsin L was inversely correlated to hormone receptor status (P = 0.0014, Mann-Whitney U test) and to the presence of tumor necrosis (P = 0.009, Mann-Whitney U test). There were no correlations of cathepsin B or cathepsin L to tumor size, axillary lymph node status, age, menopausal status, tumor grading, and vessel invasion. To perform univariate analyses of disease-free survival, optimal cutoff points were determined by isotonic regression and classification and regression trees analysis. Patients with a high content of cathepsin B (>1092 ng/mg protein) or cathepsin L (>376 ng/mg protein) in their primary tumors had a statistically significantly higher risk of recurrence than patients with a low content of cathepsin B or cathepsin L (5-year disease-free survival: cathepsin B, 70% versus 52%, P = 0.04; cathepsin L, 83% versus 52%, P = 0.0002). Median follow-up was 39 (range, 6-73) months. Multivariate analysis for disease-free survival showed that cathepsin L is a strong and independent prognostic factor with a prognostic impact comparable to that of axillary lymph node status and grading. We conclude that both cathepsin B and cathepsin L may serve as prognostic factors for tumor recurrence in human breast cancer. These data underline the significance of tumor-associated proteolysis for invasion and metastasis.

Tissue cathepsins as tumor markers

In the metastatic process, proteolytic enzymes play an important role in mediating passage of the malignant cell through the cell membrane. The cathepsins are ubiquitous lysosomal proteases and are classified both functionally and according to their active site. Cathepsin D, cathepsin B and to a lesser extent other cathepsins have been described as prognostic markers in cancer. Measurements of cathepsin D in breast tissue may be significant in predicting recurrence as well as disease free and overall survival. Reported differences concerning the role of cathepsin D as a prognostic marker may be related in part to the methodology used and the employment in the assays of antibodies prepared to different portions of the molecule. The general consensus is that elevated concentrations of cathepsin D in breast cancer tissue are highly significant indicators of the potential for recurrence. Cathepsin B, which catalyzes the degradation of laminin, may play a role in the rupture of the basement membrane and may be of importance in pancreatic and colorectal cancer.

Immunocytochemical and immunoelectron microscopic demonstration of cathepsin B in human malignant melanoma

Proteases are known to enhance the spread of tumour cells. Possible sources of these proteases are the tumour cells themselves or fibroblasts in the tumour tissue. Immunological staining with anticathepsin B antibody indicates that the subcellular distribution of cathepsin B in tumour cell lines differs from that in normal liver. The aims of this study were: (i) to show whether different types of melanoma differ in their production of cathepsin B; (ii) to identify the cathepsin B-producing cells; and (iii) to determine the subcellular distribution of cathepsin B in melanoma cells. All types of melanomas contained cell regions stained with anticathepsin B antibody. The intensity of the stain and the number of cells reacting with anticathepsin B antibody depended on the size of the tumour but not on the type of melanoma. Epithelioid cells stained more intensely with anticathepsin B antibody than spindle-shaped cells. Cells staining with anticathepsin B antibody were almost exclusively tumour cells. Anticathepsin B stain was located mainly in vesicular structures which did not contain a filamentous matrix. Additional anticathepsin B stain was detected at the extracellular spaces. Hypomelanotic melanoma cells, mainly of the epithelioid type, produced most of the cathepsin B. Cathepsin B may be involved in both the degradation of possibly abnormal melanosomes and the focal degradation of the extracellular matrix.

Differential expression of cathepsins B and D in testis and epididymis of adult rats

Cathepsins are specific proteases in lysosomes that participate in the degradation of proteins, some of which are derived from endocytosis. In this study we examined the immunocytochemical localization of cathepsin B and D antibodies in cells of rat testis and epididymis, using light and electron microscopic immunocytochemistry. In testis, cathepsin D was immunolocalized over lysosomes of Sertoli cells and Leydig cells and on the acrosome of spermatids. Cathepsin B was found over lysosomes of macrophages. Non-ciliated cells of the efferent ducts revealed intense immunogold labeling over lysosomes with both anti-cathepsin B and D antibodies. In epididymis, cathepsins B and D showed marked variations in expression over the different epithelial cells and regional differences for a given cell type. Anti-cathepsin D antibodies showed intense labeling over lysosomes of principal cells in the corpus and proximal cauda. In contrast, anti-cathepsin B antibodies revealed intensely labeled lysosomes of principal cells of the distal initial segment, intermediate zone, and caput epididymidis, with weaker labeling in other regions. Clear cells of the proximal caput epididymidis revealed intensely labeled lysosomes for anti-cathepsin D antibodies. In the distal caput, clear cells showed a variable reaction pattern from intensely labeled to unreactive. Basal cells of teh intermediate zone and proximal caput region were intensely reactive for anti-cathepsin D antibodies. There was no staining over clear or basal cells with anti-cathepsin B antibodies. Taken together, these results demonstrate cell-specific and regional differences in the distribution of cathepsins B and D in cells of the male reproductive system. Such results suggest substrate specificity with regard to protein turnover within lysosomes of cells of testis and epididymis.

The septoclast, a cathepsin B-rich cell involved in the resorption of growth plate cartilage

At the transition between growth plate cartilage and the endochondral bone region, transverse septa are being eroded to allow the advance of invasive capillaries. To find out whether resorption is due to proteinase activity, tissue sections prepared from the growth plate/metaphyseal interface of young rats were immunostained with antibodies to the cysteine proteinase cathepsin B. Intense staining was found in a cell that is associated with the growing portion of the invasive capillaries and extends between them and the transverse septum. This cell has a single nucleus, actively synthesizes protein, and shows two other characteristic features: the cytoplasm is packed with multivesicular and dense bodies rich in cathepsin B, and the cell apex ends in a ruffled border extending into the transverse septum and signs of dissociated extracellular matrix. Even though the ruffled border resembles that of the osteoclast, the cell was not immunostained by a monoclonal antibody that recognizes a 97 KD protein known as ED1 which characterizes rat osteoclasts, monocytes, and macrophages. Therefore, this distinctive cell produces the proteinase cathepsin B and appears to be involved in the resorption of the transverse septum. The cell has been named the "septoclast."

Thiolprotease activity in skeletal and myocardial muscle and liver of fasted rats

The activity of the thiolproteases, cathepsins B, H, and B + L, one of the most important groups of endoproteases, was measured in skeletal and myocardial muscle and liver of Sprague-Dawley rats submitted to fasts of different duration (control and 24, 48, and 72 h). After the fasting period, the animals were killed, and fresh tissue samples were collected. Enzyme activity was determined in vitro with the specific substrates Z-Arg-Arg-MCA for cathepsin B, Z-Phe-Arg-MCA for cathepsin B + L, and Arg-MCA for cathepsin H. Results show different patterns in the organs studied: activity increased linearly in liver, decreased in myocardial muscle, and had no change in skeletal muscle. These results suggest that the expected alteration observed in proteolytic activity in fasted tissues is produced to a certain degree by changes in thiolprotease activity.

Cathepsin B in osteoarthritis: cytochemical and histochemical analysis of human femoral head cartilage

OBJECTIVE

To localise the cysteine endopeptidase cathepsin B in chondrocytes and cartilage from normal and osteoarthritic (OA) human femoral heads in order to provide qualitative information on its cellular expression and distribution at possible sites of action.

METHODS

OA articular cartilage was obtained at surgery for total hip replacement; control cartilage was obtained at postmortem. Chondrocytes were isolated by sequential enzymatic digestion and cathepsin B analysed by immunocytochemistry and activity staining with a fluorogenic substrate. Lysosomes were visualised by fluorescence microscopy after staining of living cells with acridine orange. Using a histochemical reaction, enzyme activity was measured in cryosections of full thickness cartilage.

RESULTS

Chondrocytes from normal cartilage contained very few lysosomes and only a minor cell population was cathepsin B positive. A high proportion of chondrocytes from active OA cartilage contained a large number of lysosomes and an excess of cathepsin B in intracellular organelles; the enzyme was stored in an active form. In this respect, OA chondrocytes closely resembled normal cells that had been phenotypically modulated by serial subcultures. No cathepsin B activity could be detected by histochemistry in either chondrocytes or matrix of normal cartilage. While apparently intact and severely degraded OA cartilage was also cathepsin B negative, tissue at sites of active destruction and, particularly, at repair sites was highly positive.

CONCLUSION

The presence and the particular distribution of active cathepsin B in OA cartilage at 'more involved' sites suggest a pathological role for this enzyme in sustaining and perpetuating cartilage degradation. While other stimuli may also be responsible for cathepsin B expression in OA chondrocytes, the similarity with artificially modulated cells indicates fibroblastic metaplasia as a plausible mechanism.

A protease assay using time-resolved lanthanide luminescence from an engineered calcium binding protein substrate

OBJECTIVES

The objective of this work was to demonstrate the utility of luminescence from lanthanides bound to a mutant of the Ca2+ binding protein, oncomodulin, to monitor protease activity.

DESIGN AND METHODS

A mutant of oncomodulin with a cysteine residue at position 57 located in the CD binding loop was conjugated to a salicylic acid group. The luminescence of Tb3+ resulting from electronic energy transfer from the salicylic acid group was monitored using time resolved lanthanide luminescence in the presence of proteolytic enzymes.

RESULTS

Low detection limits for subtilisin (150 pg), chymotrypsin (2.5 ng), cathepsin B (3.5 ng), and HIV-1 protease (25 ng) were found.

CONCLUSION

The simplicity of the assay coupled with its high level of sensitivity make it useful for the detection of protease at very low concentrations.

Immunohistochemical localization of cathepsin B in neoplastic human prostate

Cathepsin B (CB) has been shown to degrade extracellular matrix (ECM) proteins, and has been reported to be involved in invasion and metastasis of several types of solid organ tumors in human and animals, but CB has not been studied in human prostate cancer (CAP). Our objective was to determine the CB protein immunostaining pattern in CAP and to correlate the immunostaining with the degree of malignancy as reflected in the Gleason grading system. We used two types of CB antibodies (namely, monospecific, polyclonal antibodies to human liver CB prepared in rabbits, and polyclonal antibody produced in sheep) to establish CB localization patterns in neoplastic prostate. Our analysis showed a heterogeneous CB immunostaining pattern in the neoplastic human prostate. CB immunostaining occurred in many, but not all, of the neoplastic columnar/cuboidal cells of acini and isolated cells, i.e., in small ragged glands and clusters (groups) of invasive cells in the prostatic stroma. We have shown that, in general, there was a positive correlation of the intensity of CB immunostaining with the Gleason histologic score (or Gleason grade sum) tumors, i.e., from the lowest scores through score 8, but many of the tumors with scores 9 and 10 showed little CB immunostaining. Our study indicated that the increased CB immunostaining in the Gleason grade sum 5-8 tumors may be associated with increased degradation of ECM, but not in 9 and 10 despite the fact that the latter tumors are more malignant clinically. In well-differentiated tumors, fewer CB immunostaining cells were present than the moderately-differentiated tumors. In other words, most of the stromal invasion of the prostatic ECM occurred in tumors of Gleason grade sums 5-8. We suggest that CB immunostaining might be a useful method to assess stromal invasion of prostatic carcinoma, especially in the higher grade tumors.

Cathepsin B in angiogenesis of human prostate: an immunohistochemical and immunoelectron microscopic analysis

BACKGROUND

Angiogenesis (or neovascularization) is required for the growth of solid organ tumors and precedes invasion of the adjacent stroma by neoplastic cells. We investigated the relative density and distribution of cathepsin B (CB) immunostained microvessels (i.e., small blood vessels and capillaries) in benign prostatic hyperplasia (BPH), prostatic intraepithelial neoplasia (PIN), and prostatic adenocarcinoma (CAP) by immunocytochemical localization of an antibody directed against a cathepsin B-derived synthetic peptide (Syn-CB).

METHODS

We studied 16 formalin-fixed, prostatectomy specimens that were embedded in paraffin/paraplast for histological examination by hematoxylin and eosin and immuno-localization of the Syn-CB antibody. Selected paraformaldehyde-fixed specimens were embedded in K4M Lowicryl or LRWhite resins. We localized the antibody in thin sections using immunoelectron microscopy techniques.

RESULTS

Eight patients had BPH [4 patients with BPH alone, 2 with BPH and PIN, and 2 with BPH and CAP]. Ten cancer cases included one with Gleason histologic score 4, two with score 6, four with score 7, and three with score 8. In CAP cases, Gleason score 6 and 7 tumors had more microvessels than the score 4 or 8 tumors. In both BPH and CAP cases, the antibody was localized chiefly in the endothelial cells of microvessels, but occasionally in ductal and glandular epithelial cells. Ultrastructurally, CB-immunoreactive gold particles were markedly increased at the luminal and basal plasma membrane surfaces and folds of endothelial cells in neoplastic prostate, but not in the endothelial cells of BPH. Furthermore, the presence of CB localizing gold particles in collagen and smooth muscle fibers near the microvessels indicated leakage of the enzyme in prostatic stroma of neoplastic prostate. Similar leakage was not observed in BPH. Morphometric analysis showed that the relative density of microvessels increased two to three times in cancer patients when compared to patients with BPH alone. Our study also indicated that BPH associated with PIN or CAP had an increased density of microvessels when compared to BPH alone.

CONCLUSIONS

Our study showed that the relative density and distribution of microvessels are the most important features of neovascularization in prostatic tumors. The relative density of microvessels increased in PIN and CAP when compared to BPH alone. Although the localization of CB is associated with lysosomes of endothelial cells in both BPH and CAP, there is a greater association of CB with the plasma membranes of endothelial cells in CAP than BPH. Immunoelectron microscopy provided evidence that CB might be involved in dissolution of basement membranes in neoplastic tumors during angiogenesis. CB localization has the potential of defining a role for this protease in degradation of extracellular matrix constituents during early steps of angiogenesis.

Assessment of cathepsin L activity by use of the inhibitor CA-074 compared to cathepsin B activity in human lung tumor tissue

In a series of pairs of lung tumor tissue and non-tumor lung parenchyma from 50 patients, the activity of cathepsin L was measured with Z-Phe-Arg-AMC using the inhibitor CA-074 to delimitate from cathepsin B activity also present in the tissue extracts. Cathepsin B was assessed in the same samples with its specific substrate Z-Arg-Arg-AMC. It was found that in tumor tissue the median activities of cathepsin L and cathepsin B were increased 1.6-fold and 4.9-fold, respectively. The levels of activity of both enzymes did not correlate with TNM stages nor with cell differentiation of bronchial carcinomas. Cathepsin L activity was found to be insignificantly higher in adenocarcinoma compared to squamous cell carcinoma, while cathepsin B activity did not vary across the histologies. The activities of both enzymes were low in pulmonary carcinoids, which are known to be low-grade malignant neoplasms. The amount of cathepsin B activity exceeded by far that of cathepsin L activity as proven by measurement with Z-Phe-Arg-AMC in the presence of the inhibitor Z-Phe-Phe-CHN2:95-98% of cathepsin B activity vs 2-5% of cathepsin L activity were determined. By SDS-PAGE separation and immunoblot analysis, it could be demonstrated that significant amount of cathepsin L is complexed with the cysteine proteinase inhibitor kininogen. This explains the rather low cathepsin L activity values in the tissue extracts.

Effects of dexamethasone on protein degradation and protease gene expression in rat L8 myotube cultures

We examined the effects of a synthetic glucocorticoid (dexamethasone; Dex) on protoeolysis and on protease messenger RNA (mRNA) concentrations in rat L8 skeletal myotube cultures. Protein degradation was measured as release of radioactive trichloroacetic acid-soluble material from intracellular proteins pre-labelled with [3H]tyrosine. Dex (1 microM) stimulated protein degradation (P < 0.01). This effect was entirely blocked by the glucocorticoid antagonist, RU38486 (mifepristone; P < 0.01). Hence, actions of Dex on muscle protein degradation are mediated via intracellular glucocorticoid receptors. Molecular mechanisms by which glucocorticoids stimulate protein degradation in skeletal muscle are not known. Here, we investigated the regulation of protease (cathepsin B, cathepsin D, proteasome C2 subunit and m-calpain) mRNA concentrations by Dex in cultured L8 muscle cells. Cathepsin B mRNA concentration was enhanced 3.3-fold by Dex. This effect was blocked by RU38486. RU38486 alone did not affect cathepsin B mRNA concentration or mRNAs of other proteases. Concentrations of cathepsin D and m-calpain mRNAs were also increased by Dex. These effects were also abolished by RU38486. Proteasome C2 mRNA was unaffected by Dex and Dex reduced alpha-tubulin mRNA. Thus, glucocorticoids specifically regulate the concentrations of mRNAs encoding some proteases in muscle cells. The regulation of protease mRNA concentration is mediated via interaction between Dex with glucocorticoid receptors and is independent of the actions of Dex on mRNA encoding house-keeping proteins. These changes may underlie glucocorticoid-dependent control of proteolysis in muscle.

Clinical relevance of cathepsin B-like enzyme activity and cysteine proteinase inhibitor in melanocytic tumours

We studied the relationship between cathepsin B (CB)-like enzyme activities and cysteine proteinase inhibitor (CPI) activities in lesions of human pigmented naevi (PN), primary melanomas (PM) and metastases/metastatic melanomas (MM). The CB-like enzyme activities in PM and MM were 2.5 and 6.8 times higher than in PN, respectively. The CB-like/CPI ratios in PM and MM were 1.9 and 11.6 times higher than in PN, respectively. CPI had the highest activity in PM and the lowest activity in MM. The disease-free interval of patients with a high CB-like enzyme activity (> or = 80 U/mg protein) and/or a high CB-like/CPI ratio (> or = 7) was shorter than that of patients with a low CB-like enzyme activity (< 80 U/mg protein) and/or a low CB-like/CPI ratio (< 7). Analysis of CB-like enzyme activity and/or the CB-like/CPI ratio may be useful in predicting the prognosis of human malignant melanoma.

Prognostic value of total cathepsin B in invasive ductal carcinoma of the breast

Total cathepsin B (catB) was determined by ELISA in 62 specimens of invasive ductal carcinoma of the breast. It was measured in microgram/g of tumour protein (microgram/gtp). The median catB was 91 micrograms/gtp, not varying significantly with T-stage or with age. It was higher in lymph-node negative (143 micrograms/gtp) than in lymph-node positive patients (49 micrograms/gtp) (P = 0.0005), in grade 3 (132 micrograms/gtp) than in grade 1 and 2 tumours (72 micrograms/gtp) (P = 0.07) and in hormone receptor-negative (155 micrograms/gtp) than in hormone receptor-positive tumours (72 micrograms/gtp) (P = 0.025). The recurrence-free survival (RFS) at 54 months for patients with tumours with catB < or = 23 micrograms/gtp was 22% and for catB > 23 micrograms/gtp, 68% (P = 0.0004). CatB > 23 micrograms/gtp did not significantly influence the RFS. Multivariate analysis showed that lymph nodes involvement (P = 0.003) and catB (P = 0.007) were independent prognostic factors.

Pericellular pH affects distribution and secretion of cathepsin B in malignant cells

Redistribution of lysosomes to the cell surface and secretion of lysosomal proteases appear to be general phenomena in cells that participate in local proteolysis. In the present study, we have determined whether malignant progression affects the intracellular distribution and secretion of the lysosomal protease cathepsin B in three model systems, each of which consists of cell pairs that differ in their degree of malignancy. The intracellular distribution of vesicles staining for cathepsin B was evaluated by immunofluorescent microscopy and the secretion of cathepsin B was evaluated by two complementary techniques: stopped assays of activity secreted into culture media; and continuous assays of activity secreted from viable (> or = 95%) cells growing on coverslips. We observed that the intracellular distribution of cathepsin B+ vesicles was more peripheral in the cells of higher malignancy in all three model systems and that active cathepsin B was secreted constitutively from these cells. Because an acidic pericellular pH has been shown to induce translocation of lysosomes in macrophages and fibroblasts, we evaluated the intracellular distribution of cathepsin B+ vesicles and secretion of cathepsin B in cell pairs incubated at slightly acidic pH. Acidic pericellular pH induced a redistribution of cathepsin B+ vesicles toward the cell periphery. In the more malignant cells, this resulted with time in reduced intracellular staining for cathepsin B and enhanced secretion of active cathepsin B. Translocation and secretion of cathepsin B were dependent on a functional microtubular system. Both the redistribution of cathepsin B+ vesicles toward the cell surface induced by acidic pH and the constitutive and acidic pH-induced secretion of active cathepsin B could be inhibited by microtubule poisons and stabilizers. We suggest that the redistribution of active cathepsin B to the surface of malignant cells and its secretion may facilitate invasion of these cells.

Cathepsin B expression and localization in glioma progression and invasion

The poor prognosis of human malignant gliomas is due to their invasion and recurrence, the molecular mechanisms of which remain poorly characterized. We have accumulated substantial evidence implicating the cysteine protease cathepsin B in human glioma malignancy. Increases in cathepsin B expression were observed throughout progression. In primary brain tumor tissue, transcript abundance (Northern blot analysis) increased in low-grade astrocytoma to high-grade glioblastoma from 3- to 6-fold, respectively, above normal brain levels. This increase correlated with increases in protein abundance (from + to ) as measured by immunohistochemistry. Furthermore, in glioblastoma cell lines increases in transcript abundance (ranging from 3- to 12-fold) were accompanied by increases in enzyme activity (44-133 nmol/min x mg protein). Altered subcellular localization was observed both immunohistochemically and by indirect immunofluorescence confocal microscopy and was found to correlate with increased grade. In addition, this increase in cathepsin B expression and altered subcellular localization correlated with histomorphological invasion and clinical evidence of invasion as detected by magnetic resonance imaging. These data support the hypothesis that cathepsin B plays a role in human glioma progression and invasion.

Cathepsin B expression and laminin degradation as factors influencing prognosis of surgically treated patients with lung adenocarcinoma

We examined, immunohistochemically, tissues from primary lung adenocarcinomas. In 142 tumors, the mean overall labeling percentage of cathepsin B was 26.5 +/- 22.3 (SD). The mean labeling percentage of cathepsin B in cases with stage I disease was lower than that in cases with stages IIIA, IIIB, or IV disease (P < 0.05). Of the 115 tumors examined for laminin-positive basement membranes, 54 (47%) had a continuous pattern and 61 (53%) had a discontinuous pattern. The mean labeling percentage of cathepsin B was 35.0 +/- 24.2 in tumors with a discontinuous pattern, compared with the 21.9 +/- 16.9 in those with a continuous pattern (P < 0.01). The overall 5-year survival rates of patients with high and low cathepsin B expressions were 26% and 77%, respectively (P < 0.01), including 45% and 94% for patients with stage I disease, respectively (P < 0.01), and 15% and 60% for those with stage IIIB disease, respectively (P < 0.05). Multivariate analysis using the Cox life table regression model showed cathepsin B to be a significantly independent factor associated with death due to the disease. We conclude from this study that tumors with a discontinuous pattern of laminin have a higher percentage of cathepsin B, and the survival rate was poor for patients with a high expression of cathepsin B. Thus, cathepsin B may be useful in assessing prognosis in lung adenocarcinoma.

Cathepsin B, a cysteine protease implicated in metastatic progression, is also expressed during regression of the rat prostate and mammary glands

We have developed a novel library-to-library cross-screening technology to clone unique mRNAs that are expressed during tissue regression. We have cloned a number of regression selected genes (RSG) that are expressed during the regression of the mammary gland and ventral prostate of the rat after the removal of the respective trophic hormone. In this investigation, we have characterized one of these genes, RSG-2, that is homologous to cathepsin B, a thiol protease that has been previously identified as one of the extracellular proteases which is activated in metastatic cells. The steady-state levels of RSG-2 mRNA in the normal prostate are low but detectable. In the regressing prostate, RSG-2 mRNA levels peak at 3-4 days after castration, at the time that tissue regression is maximal. The gene is induced in a similar fashion in the regressing mammary gland. Using in situ hybridization, we have established that RSG-2 mRNA is expressed in the luminal epithelial cells of the prostate and mammary gland that are known to undergo active cell death, suggesting that it may be a general marker for secretory epithelial cell death. Analysis of the distribution of the cathepsin B protein by immunofluorescence microscopy demonstrates that there is diffuse, but punctate, expression of the protein in all of the luminal epithelial cells of the normal prostate and mammary gland. However, at early times after hormone ablation in both glands, the majority of the increase in cathepsin B protein appears to result from redistribution to the basal aspect of the cells. At later time points, there appears to be increased amounts of the protein which is localized to the apoptotic bodies. These results suggest that RSG-2, or cathepsin B, is required for the local degradation of the basement membrane, which is one of the earliest morphologically recognizable events of active cell death.