Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cathepsin B”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2002

[Enzymatic activity of cathepsin B, cathepsin B and L, plasmin, trypsin and collagenase in hepatocellular carcinoma].

UNLABELLED: Hepatocellular carcinoma is one of the most common malignancies worldwide. Invasiveness of this tumour seems to be related to degradation of extracellular matrix. Such proteolytic enzymes as: cathepsin B and L, plasmin, collagenase and trypsin are thought to play a pivotal role in this process. Enzymatic activity depends on balance between enzymes and their inhibitors and--moreover--on interactions among these enzymes. The purpose of our study was to evaluate enzymatic activity of cathepsin B, cathepsin B and L, plasmin, collagenase and trypsin in patients with hepatocellular carcinoma in liver tissue and in peripheral blood. Then correlations between activity of enzymes (mentioned above) and clinical status, pathological findings and laboratory tests were assessed. Our study was conducted on 14 patients who underwent surgery because of hepatocellular carcinoma. Tissue samples were obtained during surgery from neoplastic area and from non-neoplastic area. Peripheral blood was withdrawn before surgery and within early post-operative period. Proteolytic activity of these enzymes was determined with use of fluorometric assay. Enzymatic activity in tissue samples was referred to protein concentration (BCA assay) and to DNA concentration (fluorometric assay). RESULTS: Proteolytic activity of plasmin and trypsin in neoplastic tissue were significantly lower as compared to non-neoplastic area of these patients (p = 0.0356; p = 0.0412, respectively). Activity of the remaining enzymes: cathepsin B, cathepsin B and L and collagenase did not differ significantly. No difference was demonstrated between activity of enzymes in peripheral blood withdrawn before surgery and in postoperative period. There was a statistically significant inverse correlation between serum AFP level and enzymatic activity of cathepsin B, cathepsin B and L and collagenase in tumor tissue. Lower activity of all investigated enzymes was observed in tumor tissue of HBV related hepatocellular carcinoma in comparison with the remaining tissue samples. Correlation between patients age and activity of enzymes was not statistically significant. CONCLUSION: Although the evaluation of presented enzymatic profile did not allow for the assessment of associations between investigated enzymes, our results demonstrated correlations between proteolytic activity of enzymes and serum AFP level, viral status, but it requires further investigations.

Adult↗
PubMed1985

Action of brain cathepsin B, cathepsin D, and high-molecular-weight aspartic proteinase on angiotensins I and II.

The action of three previously isolated electrophoretically homogeneous brain proteinases--cathepsin B (EC 3.4.22.1), cathepsin D (EC 3.4.23.5), and high-molecular-weight aspartic proteinase (Mr = 90K; EC 3.4.23.-)--on human angiotensins I and II has been investigated. The products of enzymatic hydrolysis have been identified by thin-layer chromatography on Silufol plates using authentic standards and by N-terminal amino acid residue analysis using a dansyl chloride method. Cathepsin D and high-molecular-weight aspartic proteinase did not split angiotensin I or angiotensin II. Cathepsin B hydrolyzed angiotensin I via a dipeptidyl carboxypeptidase mechanism removing His-Leu to form angiotensin II, and it degraded angiotensin II as an endopeptidase at the Val3-Tyr4 bond. Cathepsin B did not split off His-Leu from Z-Phe-His-Leu. Brain cathepsin B may have a role in the generation and degradation of angiotensin II in physiological conditions.

Angiotensin I↗
PubMed1995

Hairpin loop mutations of chicken cystatin have different effects on the inhibition of cathepsin B, cathepsin L and papain.

Five recombinant hairpin loop variants of chicken cystatin (delta V55, delta V55-S56, delta P103-L105, delta I102-Q107, loop2-KD2) were constructed by cassette mutagenesis, expressed in E. coli, purified to homogeneity, characterized by protein-chemical means and by their inhibitory properties. The variant forms, modified in two of the three postulated cysteine proteinase binding regions, were inhibitorily active. However, the equilibrium dissociation constants of the complexes between papain as well as human cathepsin B or L and the cystatin variants show a weaker affinity for all three enzymes compared with recombinant chicken cystatin. These results prove the contribution of both hairpin loops to complex formation with the three enzymes. Furthermore, the kinetic constants indicate discrete differences in the molecular mechanism of interaction between chicken cystatin and papain, cathepsin B, and cathepsin L. Inhibition of cathepsin L was much less affected than inhibition of papain or cathepsin B by the modifications achieved in the five variants. Remarkably, at high enzyme concentration (above 0.5 nM) inhibition of papain by these variants was 'temporary', that means, active papain was released from the enzyme-inhibitor complex within minutes to hours (compare [1]).

Amino Acid Sequence↗
PubMed1981

Rat liver thiol proteinases: cathepsin B, cathepsin H and cathepsin L.

Data on following points of lysosomal thiol proteinases (cathepsins B, H and L) from rat liver are described in this paper: Partial amino acid sequence of cathepsin B, substrate specificity of cathepsin L, immunological studies of cathepsin B and H and effectiveness of E-64, specific thiol proteinase inhibitor in vivo.

Amino Acid Sequence↗
PubMed2002

Comparison of potential biological markers cathepsin B, cathepsin L, stefin A and stefin B with urokinase and plasminogen activator inhibitor-1 and clinicopathological data of breast carcinoma patients.

Cysteine, serine and metalloproteinases and their respective inhibitors are involved in tumor cell invasion and may have prognostic value for the outcome of malignant disease. The aim of the study was to compare the expression of new potential biological tumor markers, the lysosomal cysteine proteinases and their endogenous inhibitors, with that of the serine proteinases and their inhibitors in breast cancinoma and to relate their levels to the clinicopathological factors of the disease. Enzyme-linked immunosorbent assays (ELISAs) were used to measure cysteine cathepsin B (CatB) and cathepsin L (CatL) and their inhibitors, stefin A (StA) and stefin B (StB), together with urokinase (u-PA) and plasminogen activator inhibitor-1 (PAI-1), in 150 cytosols of primary invasive breast carcinoma. A good correlation was found between the levels of the two cysteine proteinases but only a moderate one between those of the cysteine and serine proteinases. u-PA and PAI-1 levels correlated positively with histological grade and negatively with estrogen receptor (ER) status. PAI-1 correlated with most clinicopathological factors that indicate the progression of the disease, while cathepsins and stefins were independent of these factors. In the total group of patients, high u-PA and PAI-1 and low StB levels correlated significantly with shorter disease-free survival (DFS), while CatB, CatL and StA did not. In lymph node negative patients, high CatB and CatL were also associated with shorter DFS, while u-PA remained the most significant of all these biological markers. In conclusion, this retrospective study showed u-PA to be of better prognostic relevance than the cysteine proteinases, though CatB and CatL were relevant for prognosis in lymph node negative breast cancer patients.

Adult↗
PubMed1995

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.

Adult↗
PubMed2000

Fluorescent microplate assay for cancer cell-associated cathepsin B.

Cathepsin B and in particular cell-surface and secreted cathepsin B has been implicated in the invasive and metastatic phenotype of numerous types of cancer. We describe here a method to easily survey cancer cell lines for cathepsin B activity using the highly selective substrate Z-Arg-Arg-AMC. Intact human U87 glioma cells hydrolyze Z-Arg-Arg-AMC with a Km of 460 microM at pH 7.0 and 37 degrees C. This is nearly the same as the Km of 430 microM obtained with purified cathepsin B assayed under the same conditions. The pericellular (i.e. both cell-surface and released) cathepsin B activity was inhibited by the cysteine protease inhibitors E-64, leupeptin, Mu-Np2-HphVS-2Np, Mu-Leu-HpHVSPh and the cathepsin B selective inhibitor Mu-Tyr(3,5 I2)-HphVSPh with IC50 values similar to those observed for the inhibition of purified human liver cathepsin B. Other human cancer cell lines with measurable pericellular cathepsin B activity included HT-1080 fibrosarcoma, MiaPaCa pancreatic, PC-3 prostate and HCT-116 colon. Cathepsin B activity correlated with protein levels of cathepsin B as determined by immunoblot analysis. Pericellular cathepsin B activity was also detected in the rat cell lines MatLyLu prostate and Mat B III adenocarcinoma and in the murine lines B16a melanoma and Lewis lung carcinoma. The ability to determine pericellular cathepsin B activity will be useful in selecting appropriate cell lines for use in vivo when analyzing the effects of inhibiting cathepsin B activity on tumor growth and metastasis.

Animals↗
PubMed2005

Specific human antibodies do not inhibit Trypanosoma cruzi oligopeptidase B and cathepsin B, and immunoglobulin G enhances the activity of trypomastigote-secreted oligopeptidase B.

Trypanosoma cruzi expresses oligopeptidase B and cathepsin B that have important functions in the interaction with mammalian host cells. In this study, we demonstrated that sera from both chagasic rabbits and humans have specific antibodies to highly purified native oligopeptidase B and cathepsin B. Levels of antibodies to cathepsin B were higher than those observed to oligopeptidase B by absorbance values recorded upon ELISA. We next showed that 90% and 30% of sera from individuals with mucocutaneous leishmaniasis have antibodies that recognize oligopeptidase B and cathepsin B as antigens, respectively. In addition, 55% and 40% of sera from kala-azar patients have antibodies to oligopeptidase B and cathepsin B, respectively. Sera from malaria patients did not recognize the proteases as antigens. Despite high levels of specific antibodies, sera from T. cruzi-infected patients did not inhibit the activities of either oligopeptidase B or cathepsin B. Furthermore, sera or IgG purified from either infected or non-infected individuals enhanced the enzymatic activity of the secreted oligopeptidase B. Oligopeptidase B secreted by trypomastigotes and cathepsin B released upon parasite lysis retain their enzymatic activities and may be associated with Chagas' disease pathogenesis by hydrolyzing host proteins and inducing host immune responses.

Animals↗
PubMed2006

Inhibitors of cathepsin B.

Cathepsin B is an abundant and ubiquitously expressed cysteine peptidase of the papain family. It is involved in many physiological processes, such as remodeling of the extracellular matrix (wound healing), apoptosis, and activation of thyroxine and renin. In addition to its physiological roles, cathepsin B is important in many pathological processes, such as inflammation, parasite infection and cancer, where it is highly up-regulated. In cancer patients, elevated cathepsin B activity correlates to poor therapy outcome. Therefore, it is not surprising that the use of cathepsin B inhibitors reduces both tumor cell motility and invasiveness in vitro. This review summarizes recent developments in cathepsin B inhibition. To date, numerous protein inhibitors of cathepsin B have been described, some of which are of endogenous origin and function as regulators of cathepsin B activity in the cell, such as the cystatins. In addition, some exogenous protein inhibitors of cathepsin B have been isolated from various natural sources, and the use of X-ray crystal structures of cathepsin B complexed with such protein inhibitors has resulted in the design and synthesis of many new small-molecular-weight compounds as inhibitors of cathepsin B. These synthetic compounds generally contain an electrophilic functionality that reacts with cathepsin B. In the present review, these inhibitors are divided according to their mechanisms of action, as reversible and irreversible, and then further subdivided into groups for their full descriptions.

Cathepsin B↗
PubMed2004

Fluorogenic peptide substrates for carboxydipeptidase activity of cathepsin B.

Cathepsin B is a lysosomal cysteine protease exhibiting mainly dipeptidyl carboxypeptidase activity, which decreases dramatically above pH 5.5, when the enzyme starts acting as an endopeptidase. Since the common cathepsin B assays are performed at pH 6 and do not distinguish between these activities, we synthesized a series of peptide substrates specifically designed for the carboxydipeptidase activity of cathepsin B. The amino-acid sequences of the P(5)-P(1) part of these substrates were based on the binding fragments of cystatin C and cystatin SA, the natural reversible inhibitors of papain-like cysteine protease. The sequences of the P'(1)-P'(2) dipeptide fragments of the substrates were chosen on the basis of the specificity of the S'(1)-S'(2) sites of the cathepsin B catalytic cleft. The rates of hydrolysis by cathepsin B and papain, the archetypal cysteine protease, were monitored by a continuous fluorescence assay based on internal resonance energy transfer from an Edans to a Dabcyl group. The fluorescence energy donor and acceptor were attached to the C- and the N-terminal amino-acid residues, respectively. The kinetics of hydrolysis followed the Michaelis-Menten model. Out of all the examined peptides Dabcyl-R-L-V-G-F- E(Edans) turned out to be a very good substrate for both papain and cathepsin B at both pH 6 and pH 5. The replacement of Glu by Asp turned this peptide into an exclusive substrate for cathepsin B not hydrolyzed by papain. The substitution of Phe by Nal in the original substrate caused an increase of the specificity constant for cathepsin B at pH 5, and a significant decrease at pH 6. The results of kinetic studies also suggest that Arg in position P(4) is not important for the exopeptidase activity of cathepsin B, and that introducing Glu in place of Val in position P(2) causes an increase of the substrate preference towards this activity.

Amino Acid Sequence↗
PubMedDate not supplied

Degradation of laminin by human tumor cathepsin B.

Cathepsin B activity, including that of a plasma membrane-associated cathepsin B, has been linked to tumor malignancy. As cathepsin B at the tumor cell surface has been hypothesized to play a role in the focal degradation of basement membrane during the metastatic cascade, we have examined the ability of human tumor cathepsin B to degrade laminin, an adhesive glycoprotein found exclusively in the basement membrane. We report that at pH 6.5 and 7.0 tumor cathepsin B degraded by specific, limited proteolysis both subunits of native laminin. The disappearance of both subunits and the appearance of lower Mr protein bands could be observed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Accumulation of degradation products was also observed using gel filtration chromatography and a fluorescamine assay. The proteolysis of laminin by tumor cathepsin B could be inhibited by an active site titrant for cysteine proteinases or stefin B, an endogenous low-Mr cysteine proteinase inhibitor.

Cathepsin B↗
PubMed1985

Some properties of human and bovine brain cathepsin B.

Cathepsin B has been purified 750-fold to apparent homogeneity from human and bovine brain cortex using ammonium sulfate fractionation (30-70%), chromatography on Sephadex G-100, CM-Sephadex C-50, and concanavalin A-Sepharose. Enzyme was assayed fluorometrically at pH 4.0 with pyridoxyl-hemoglobin in the presence of 1 mM DTT and 1 mM EDTA. Properties of the enzyme from the two sources proved to be similar. On disc PAGE the purified preparation produced two bands associated with proteinase activity that are due to existence of two multiple forms of brain cathepsin B with pI 6.1 and 6.8. The enzyme is completely inactivated by thiol-blocking reagents, leupeptin, E-64, and demands thiol compounds for its ultimate activity. Z-Phe-Ala-CHN2 is a potent inhibitor of the enzyme (K2nd = 1280 M-1S-1) in contrast to Z-Phe-Phe-CHN2 (K2nd = 264 M-1S-1). pH optimum in the reaction of hydrolysis of Pxy-Hb is 4.0-6.0, KM(app.) = 10(-5) M. Cathepsin B splits azocasein: pH optimum 5.0-6.0, KM(app.) = 2.2 X 10(-5) M, but inclusion of urea in the incubation medium depresses the azocaseinolytic activity of the enzyme 1.5-fold. It does not split Lys-NNap, Arg-NMec and is not inhibited by bestatin. The specific activity of brain cathepsin B with Z-Arg-Arg-NNapOMe at pH 6.0 is 10-fold higher than with Bz-Arg-NNap, Z-Gly-Gly-Arg-NNap is a poor substrate. With Z-Arg-Arg-NMec and Bz-Phe-Val-Arg-NMec the specific activity is 80 and 35%, respectively of that with Z-Phe-Arg-NMec.

Animals↗
PubMed1983

Steady state kinetic evidence for an acyl-enzyme intermediate in reactions catalyzed by bovine spleen cathepsin B.

Cathepsin B from bovine spleen was shown to catalyze transacylation reactions between esters of N-substituted amino acids and nucleophiles. These reactions appeared to proceed through an intermediate between cathepsin B and the acyl portion of the substrate. Of the various nucleophiles tested, dipeptides were found to be the most effective acyl group acceptors. A method was devised for calculating the acylation and deacylation rate constants from increases in the maximum velocity of disappearance of the substrate with increasing concentrations of the nucleophile. The values for the second order rate constants for the reaction of the acyl-enzyme with the nucleophile, k4, were found to depend on the identity of the dipeptide, while the first order rate constants for formation and hydrolysis of the acyl-enzyme, k2 and k3, were dipeptide-independent. With N alpha-benzyloxycarbonyl-L-lysine p-nitrophenyl ester at pH 6.5, k2 and k3 were found to be 360 s-1 and 6.6 s-1, respectively, indicating that the deacylation step was rate-determining for the hydrolysis of this substrate. In contrast, dipeptide nucleophiles did not significantly accelerate the cathepsin B-catalyzed cleavage of either the p-nitroanilide or the 2-naphthylamide of N alpha-benzoylarginine, suggesting that the hydrolysis of these amide substrates was acylation rate-limiting. These findings support the suggestion that cathepsin B is mechanistically similar to the cysteine proteinase papain.

Acylation↗
PubMedDate not supplied

Expression, proliferation activity and clinical significance of cathepsin B and cathepsin L in operated lung cancer.

AIMS: To immunohistochemically investigate the expression of cathepsin B and cathepsin L in various lung cancer cell types in association with the patients' prognosis. MATERIALS AND METHODS: Histological slides obtained from formalin-fixed, paraffin-embedded tissue of 120 potentially curative resected lung cancer specimens (20 cases of each of the following cell types: squamous cell, adeno, large cell anaplastic, small cell anaplastic, intrapulmonary metastases, mesotheliomas) were quantitatively immunohistochemically analysed with an automated image analysing system and correlated with the patients' prognosis and the tumour proliferation rate measured by the expression of Ki-67. RESULTS: The expression of cathepsin B was most frequently present in large cell anaplastic carcinomas and missing in small cell carcinomas. That of cathepsin L was less frequently seen, and mainly expressed in macrophages and adenocarcinoma tumour cells. The structural heterogeneity of cathepsin B expression measured by syntactic structure analysis was greater than that of cathepsin L. The expression of cathepsin B is of prognostic significance in non-small cell lung cancer, and ranges directly after the pN and pT stages in multivariate statistical analysis. CONCLUSION: In concordance with the literature, the expression of cathepsin B in non-small cell lung cancer should be considered as a significant prognostic parameter in contrast to that of cathepsin L, which is not related to the patients' outcome at a statistically significant level.

Carcinoma, Non-Small-Cell Lung↗
PubMed1995

[Role and behavior of cathepsin B and cathepsin L in gastric cancer].

Cathepsin B and cathepsin L--cysteine proteinases--may play an important role in cancer invasion and metastasis. The authors determined tissue antigen concentrations of cathepsins, using the ELISA method, in 25 patients with gastric cancer (17 males, 8 females, mean age 62, range 31-84). They evaluated the possible relationship that these proteinases may have with the presence of metastases, differentiation and histotype. Significantly higher cathepsin B and cathepsin L antigen levels were found: 1. in gastric cancer tissues vs. normal tissues distant from tumors (CATB: p < 0.05, CATL: p < 0.005); 2. in diffuse vs. intestinal type cancers (p < 0.05); 3. in patients with poorly vs. well-differentiated cancers (p < 0.05); in gastric cancers with vs. without metastasis (p < 0.05). Their results confirm that cathepsin B and L play an important role in gastric cancer invasion and metastasis. Considering the significantly higher cathepsins detected in cancers with metastasis, a poor differentiation and of diffuse histotype, these proteinases could be useful for identification gastric cancer patients with a poor prognosis.

Adult↗