Lysosomal aspartic and cysteine proteinases serum levels in patients with pancreatic cancer or pancreatitis

Dual-Mechanism Quenched Fluorogenic Probe Provides Selective and Rapid Detection of Cathepsin L Activity*

Cathepsin L (CTL) is a cysteine protease demonstrating upregulated activity in many disease states. Overlapping substrate specificity makes selective detection of CTL activity difficult to parse from that of its close homologue CTV and the ubiquitous CTB. Current probes of CTL activity have limited applications due to either poor contrast or extra assay steps required to achieve selectivity. We have developed a fluorogenic probe, CTLAP, that displays good selectivity for CTL over CTB and CTV while exhibiting low background fluorescence attributed to dual quenching mechanisms. CTLAP achieves optimum CTL selectivity in the first 10 min of incubation, thus suggesting that it is amenable for rapid detection of CTL, even in the presence of competing cathepsins.

EUS-FNA cytological material from pancreatic lesions: the expression of cathepsins and its predictive value of malignancy

AIMS

To assess the expression of cathepsins in pancreatic samples obtained by endoscopic ultrasonography and fine needle aspiration (EUS-FNA) and to investigate their relationship with the staging of the pancreatic ductal adenocarcinoma (PDAC).

METHODS

We prospectively included patients with solid pancreatic masses, in which EUS-FNA were performed. Cathepsins B, L, S and H expression was determined in FNA samples.

RESULTS

Seventeen FNA were performed. All cytological material was from PDAC. Expression of cathepsins was predominantly low (B 65%, L 23%, S 76%, and H 41%). We found no correlation between the expression levels and the extension of the neoplasm.

CONCLUSION

Expression of cathepsins in the cytological material of PDAC is diverse but still poor to be useful in the pre-operative diagnosis. There is no correlation between the expression levels of cathepsins and the extension of the PDAC.

Cysteine Proteinases and Their Inhibitors in Extracellular Fluids: Markers for Diagnosis and Prognosis in Cancer

Cathepsins B, H and L have been shown to participate in processes of tumor growth, vascularization, invasion and metastasis. Their levels in tumor tissue extracts can provide useful clinical information to predict disease-free and overall survival in breast, lung, colorectal, brain and head and neck cancer patients. Recently we have found that both cysteine cathepsins and their endogenous protein inhibitors stefins and cystatin C can also predict prognosis when measured extracellularly. In melanoma and colorectal cancer patients high serum levels of cathepsins B and H correlated with shorter survival. Similarly, increased extracellular levels of stefins A and B and cystatin C correlated significantly with high risk of adverse outcome in cancer patients. However, the cathepsin B/cystatin C complex was found to be less abundant in sera of patients with malignant tumors than in those with benign diseases or in healthy controls, suggesting an imbalance between the enzyme and its inhibitor in cancer patients.

Study of the expression of cathepsins in histological material from pancreatic lesions

BACKGROUND AND AIMS

To assess the expression levels of cathepsins in malignant and premalignant lesions.

METHODS

We retrospectively included patients who underwent pancreatic surgery on pancreatic solid or cystic masses. The expression of cathepsin H, L, B and S was determined in both types of samples. Lesions were divided into three categories: malignant (pancreatic adenocarcinoma and malignant mucinous neoplasms), premalignant (mucinous neoplasms) and benign (other lesions).

RESULTS

Thirty-one surgical resection samples were studied. The expression of cathepsins was significantly higher in malignant lesions than in premalignant and benign lesions (H 75%, 27%, 37% p = 0.05; L 92%, 36%, 37% p = 0.011; B 83%, 36%, 62% p = 0.069; S 92%, 36%, 25% p = 0.004, respectively).

CONCLUSIONS

Cathepsins are overexpressed in histological samples of malignant lesions compared to premalignant and benign lesions. However, the expression of cathepsins is similar in both premalignant and benign lesions.

Cathepsin L targeting in cancer treatment

Proteolytic enzymes may serve as promising targets for novel therapeutic treatment strategies seeking to impede cancer progression and metastasis. One such enzyme is cathepsin L (CTSL), a lysosomal cysteine protease. CTSL upregulation, a common occurrence in a variety of human cancers, has been widely correlated with metastatic aggressiveness and poor patient prognosis. In addition, CTSL has been implicated to contribute to cancer-associated osteolysis, a debilitating morbidity affecting both life expectancy and the quality of life. In this review, we highlight the mechanisms by which CTSL contributes to tumor progression and dissemination and discuss the therapeutic utility of CTSL intervention strategies aimed at impeding metastatic progression and bone resorption.

Plasma cathepsin L: A prognostic marker for pancreatic cancer

AIM: To assess the prognostic significance of cathepsin L, a cysteine protease that degrades the peri-tumoral tissue, in patients with pancreatic cancer.

METHODS: Plasma samples from 127 pancreatic cancer patients were analyzed for cathepsin L levels by ELISA. Out of these patients, 25 underwent surgery and their paraffin-embedded tissue was analyzed for cathepsin L expression by immunohistochemistry. Survival of patients and clinicopathological parameters was correlated with cathepsin L expression in plasma and tissue using appropriate statistical analysis.

RESULTS: The mean (± SD) cathepsin L in plasma samples of pancreatic cancer patients was 5.98 ± 2.5 ng/mL that was significantly higher compared to the levels in healthy controls (3.83 ± 0.45) or chronic pancreatitis patients (3.97 ± 1.06). Using ROC curve, a cut-off level of 5.0 ng/mL was decided for survival analysis. Elevated plasma levels of cathepsin L were found to be associated with poor prognosis (P = 0.01) in multivariate analysis. The plasma levels of the protease decreased after surgery. Though no significant correlation was seen between plasma and tissue expression of this protease, a trend did emerge that high cathepsin L expression in tissue correlated with its high levels in plasma.

CONCLUSION: Cathepsin L levels in plasma of pancreatic cancer patients may be used as a potential prognostic marker for the disease.

Cathepsins and pancreatic cancer: the 2012 update

Pancreatic cancer is the result of distinctive genetic and epigenetic disturbances. This multistep process is in part well-defined and includes alterations in oncogenes and suppressor genes that control proliferation, apoptosis, angiogenesis, invasion and cell migration. Cathepsins are proteolytic enzymes and represent potential therapeutic targets in human tumors. Cathepsins predominantly function as endopeptidases within endolysosomal vesicles of normal cells and they are involved in physiological processes such as protein turnover, differentiation and apoptosis. In various types of malignancies, cathepsins have been associated with tumor progression and metastasis. Growing evidence and direct proofs suggest that cathepsins are highly up-regulated in pancreatic cancer and contribute to the development and progression of the cancer phenotype. In this review, the role of cathepsins in pancreatic cancer tumorigenesis is reported and discussed. Some critical aspects will be underlined such as specificity of cathepsin activity in pancreatic cancer and in its precursor lesions; the genetic perturbation and the intracellular signaling pathway activated by cathepsins as reported in preclinical models and in human tissues; the preliminary results and the oncological effects of cathepsin inhibitors currently tested on pancreatic cancer cells; the role of combined therapy based on chemotherapeutic agents and cathepsin inhibition. Although mounting evidences indicate that cysteine cathepsins are potential therapeutic targets in pancreatic cancer, as suggested by their functional role in controlling invasiveness and metastasis, it remains to be seen whether the promising benefits of pharmacological inhibitors observed in preclinical study might be translated to the current clinical practice.

The balance between extracellular cathepsins and cystatin C is of importance for ovarian cancer

BACKGROUND

A major step in cancer formation involves the degradation of the extracellular matrix, mediated by multiple degradative actions of (lysosomal) proteases. Extracellular release of lysosomal proteases (cathepsins) and their inhibitors has been associated with the development and progression of several types of cancer. We investigated whether cathepsins in ovarian cyst fluid (oCF) were associated with disease outcome in patients with epithelial ovarian cancer (EOC).

MATERIALS AND METHODS

The levels of cathepsin B (CatB), H (CatH), L (CatL) and X (CatX) and their most abundant extracellular inhibitor cystatin C (CysC) were determined in oCF of 50 EOC patients by quantitative ELISAs. The cathepsin levels and ratios between cathepsins and CysC were related to clinicopathological parameters (Mann-Whitney U and Kruskal-Wallis tests) and survival (Cox Regression analysis).

RESULTS

Median (25th-75th percentile) levels of cathepsin B, H, L, X and CysC in oCF were 97 (42-203), 18 (12-32), 61 (37-108), 20 (13-47) and 657 (501-805) ng mL(-1) respectively. Ratio of CysC/CatB was significantly lower for patients with metastatic compared with localised EOC (P = 0.025). Ratios of CysC/CatH and CysC/CatX differed significantly between histological subtypes (P = 0.012 and P = 0.035 respectively) and were significantly higher for high-grade tumours compared with low-grade tumours (P = 0.031 and P = 0.039 respectively). Neither cathepsins nor their ratios were significant predictors of survival for EOC patients.

CONCLUSIONS

Ratios between CysC and cathepsins in oCF differed significantly between important clinicopathological subgroups. We believe that a complex cascade of proteolytic events, in which cathepsins play different roles, might be responsible for progression and metastasis in EOC.

Quantitative determination and localization of cathepsin D and its inhibitors

A literature survey was performed of the methods of quantitative assessment of the activity and concentration of cathepsin D and its inhibitors. Usefulness of non-modified and modified proteins and synthetic peptides as measurement substrates was evaluated. The survey includes also chemical and immunochemical methods used to determine the distribution of cathepsin D and its inhibitors in cells and tissues.

Cathepsins B, L and cystatin C in cyst fluid of ovarian tumors

Introduction

In cancer, an extracellular and membrane bound localization of cathepsins contribute to the invasion of tumor cells at the basement membrane.

Methods

This is the first study that explored levels of cathepsins B (CatB), L (CatL) and their inhibitor cystatin C (CysC) in the cystic fluid (CF) of ovarian tumors (n = 110).

Results

CF contained considerable amounts of CatB, CatL and CysC. Remarkable differences in CatB and CatL and CysC CF levels were found between different histopathological tumor subtypes. Levels of CatB and CysC were significantly higher in CF of malignant serous tumors compared to those found in benign serous tumors (p = 0.010 and p = 0.001 respectively), whereas levels of CatL were significantly higher in CF of malignant mucinous tumors compared to those found in benign mucinous tumors (p = 0.035). CatB and CysC showed a strong correlation in the group of patients with malignant serous tumors (p < 0.001; R = 0.921) suggesting that the increase in CatB might be balanced by a corresponding increase in CysC.

Conclusion

Further studies are warranted to investigate cathepsins as possible prognostic biomarkers for the aggressiveness of ovarian cancer.

Serum cathepsin B and plasma urokinase-type plasminogen activator levels in gastrointestinal tract cancers

Cathepsin B (CATB) and urokinase-type plasminogen activator (UPA) play an important part in cancer invasion and metastasis. The behavior of CATB and UPA has not been evaluated in the same experimental setting in different gastrointestinal tumors and in precancerous lesions. Serum CATB and plasma UPA levels were determined by enzyme-linked immunoadsorbent assay and their sensitivity, specificity, and diagnostic accuracy have been calculated in patients with colorectal (n=72), gastric (n=30), hepatocellular (n=28), and pancreatic cancer (n=15) as well as in gastric epithelial dysplasia (n=25), colorectal adenomas (n=30), and tumor-free control patients (n=44). Serum CATB and plasma UPA antigen concentrations were significantly higher in patients with cancer than in controls. When all tumors were considered, the sensitivity, specificity, and diagnostic accuracy of CATB (89, 86, and 89%) were higher than that of UPA (76, 70, and 74%). CATB demonstrated in all types of tumors a better diagnostic accuracy than UPA. The positive predictive values of CATB (95%) and UPA (89%) may suggest their use in the evaluation of patients with a suspicion of malignancy. CATB and UPA were significantly higher in patients with gastric epithelial dysplasia and colorectal adenomas than in controls. Antigen levels of CATB and UPA were significantly correlated in both cancers and precancerous lesions. At the time of clinical presentation, serum CATB and plasma UPA antigen levels are sensitive indicators of gastrointestinal malignancies. Determination of serum CATB and plasma UPA levels may be useful to identify patients at a higher risk for progression to cancer, who could be subjected to a more strict follow-up protocol.

Simultaneous expression of Cathepsins B and K in pulmonary adenocarcinomas and squamous cell carcinomas predicts poor recurrence-free and overall survival

PURPOSE

Patient survival after resection of non-small cell lung cancer (NSCLC) strongly correlated with the occurrence of distant metastasis. Cathepsins are members of the lysosomal cysteine proteases family and can support the metastatic process by degrading the extracellular matrix. The purpose of this study was to identify members of the Cathepsin family that correlate with recurrence-free and overall survival of NSCLC patients.

PATIENTS AND METHODS

The expression of 13 Cathepsins was examined using DNA-microarray technology in tumor tissues of 89 surgically treated NSCLC patients. All NSCLC samples were classified according to median Cathepsin expression value into either a high or a low expression group. All Cathepsin expression groups were subjected to clinical prognostic analyses regarding survival and local as well as distant recurrences.

RESULTS

Patients with high Cathepsin C tumor expression showed higher tumor recurrence rate compared to patients with low Cathepsin C expression (p = 0.02). The tumor expression of Cathepsins K and B significantly correlated with recurrence-free and overall survival as determined by multivariate analysis. A high expression of Cathepsin B or K was associated with a considerable reduction of recurrence-free as well as overall survival. NSCLC patients with a high expression of both Cathepsin B and K had a significantly (p = 0.001) poorer outcome (5-year survival rate: 13%) than patients with low expression of both genes (5-year survival rate: 75%).

CONCLUSIONS

The combined expression level of Cathepsins B and K identifies high-risk NSCLC patients. A selection of gene expression panels is theoretically superior to established clinical and pathological criteria.

Antibody Microarray Profiling Reveals Individual and Combined Serum Proteins Associated with Pancreatic Cancer

We used antibody microarrays to probe the associations of multiple serum proteins with pancreatic cancer and to explore the use of combined measurements for sample classification. Serum samples from pancreatic cancer patients (n = 61), patients with benign pancreatic disease (n = 31), and healthy control subjects (n = 50) were probed in replicate experiment sets by two-color, rolling circle amplification on microarrays containing 92 antibodies and control proteins. The antibodies that had reproducibly different binding levels between the patient classes revealed different types of alterations, reflecting inflammation (high C-reactive protein, alpha-1-antitrypsin, and serum amyloid A), immune response (high IgA), leakage of cell breakdown products (low plasma gelsolin), and possibly altered vitamin K usage or glucose regulation (high protein-induced vitamin K antagonist-II). The accuracy of the most significant antibody microarray measurements was confirmed through immunoblot and antigen dilution experiments. A logistic-regression algorithm distinguished the cancer samples from the healthy control samples with a 90% and 93% sensitivity and a 90% and 94% specificity in duplicate experiment sets. The cancer samples were distinguished from the benign disease samples with a 95% and 92% sensitivity and an 88% and 74% specificity in duplicate experiment sets. The classification accuracies were significantly improved over those achieved using individual antibodies. This study furthered the development of antibody microarrays for molecular profiling, provided insights into the nature of serum-protein alterations in pancreatic cancer patients, and showed the potential of combined measurements to improve sample classification accuracy.

Prognostic impact of cysteine proteases cathepsin B and cathepsin L in pancreatic adenocarcinoma

OBJECTIVES

The cysteine proteases cathepsin B (CTSB) and L (CTSL) have been implicated in tumor spread and metastatic formation. In pancreatic adenocarcinoma, the role of these proteases is not very well defined. To find out which cell types produce CTSB and CTSL and to evaluate the prognostic impact of these proteases, 70 specimens from curatively resected patients with pancreatic adenocarcinoma were examined by in situ hybridization and immunohisto-chemistry.

METHODS

Seventy patients with ductal adenocarcinoma of the pancreas were studied after R0 resection with a follow-up of at least 3 years. CTSB and CTSL expression was performed immunohisto-chemically using polyclonal anti-CTSB and CTSL antibodies. To detect cell types involved in producing CTSB and CTSL as well as the intracellular localization of specific mRNA sequences, nonisotopic in situ hybridization was performed. The correlations among CTSB and CTSL expression, clinicopathologic parameters, and clinical outcome were analyzed.

RESULTS

The immunoreactivity was 96% for CTSB and 90% for CTSL. Positive mRNA signals were obtained in the cytoplasm tumor cells, macrophages, and fibroblasts in 77% for CTSB and 81% for CTSL, respectively. Statistical analysis showed a significant correlation between CTSB/CTSL expression and tumor grading (P < 0.05) and between CTSB and lymphatic invasion (P = 0.05). Kaplan-Meier analyses revealed statistical significance for CTSB/CTSL expression with the survival after curative resection (P < 0.05). Both proteases are strong prognostic markers in multivariate analysis (P = 0.0001) beside UICC stage, nodal status, tumor size, and grading (P < 0.05). Furthermore, CTSB expression is an independent prognostic marker for cancer recurrence within 6 months after curative surgery in multivariate analysis (P = 0.0001).

CONCLUSIONS

CTSB and CTSL are strong and independent prognostic markers in resectable pancreatic adenocarcinoma rather than UICC stage, TNM classification, or tumor grading. Furthermore, CTSB is a predictor for early recurrence after curative resection. These data underline the significance of tumor-associated proteolysis for cancer invasion and metastasis and may lead to defining subgroups of patients with early recurrence and poor outcome.

The metastatic potential of human pancreatic cell lines in the liver of nude mice correlates well with cathepsin B activity

BACKGROUND

Cathepsin B, a lysosomal cysteine protease, has a major role in the mechanisms of tumor metastasis. The aim of the present work was to examine the correlation between cathepsin B activity and the metastatic potential of human pancreatic cancer.

METHODS

The primary cell line COLO 357 and the derivative tumor cell lines FG, L3.1, L3.2, L3.3, L3.4, and L3.5, which are characterized by progressively increasing metastatic potential, were injected intrasplenically in the athymic mice. Cathepsin B activity, metastasis, and ultrastructural characteristics were assessed.

RESULTS

An increased number of liver tumor nodules was observed with each subsequent intrasplenic inoculation (p = 0.001), associated with lymph node, splenic, and pancreatic involvement. Cathepsin B activity progressively increased (p = 0.001) and was strongly positively correlated with the metastatic potential. However, no correlation was found between the metastatic potential and ultrastructural characteristics.

CONCLUSIONS

These findings further support the central role of cathepsin B in metastasis in a combined in vitro/in vivo model.

Serum concentration and circadian profiles of cathepsins B, H and L, and their inhibitors, stefins A and B, in asthma

BACKGROUND

In order to determine the effect of asthma on serum concentrations of cathepsins B, H and L, and stefins A and B, the circadian and concentration profiles were followed in steroid-independent and steroid-dependent asthmatics before and after 1-week treatment with methylprednisolone and cyclosporin A.

METHODS

Serum samples were taken at 4-h intervals throughout a 24-h period. Cathepsin and stefin concentrations were assayed using specific ELISAs. Data were analysed by one-way ANOVA and least squares fit of 24-h cosine.

RESULTS

Temporal analysis of these proteins revealed little or no significant changes with time over a 24-h period. In comparison to normal sera, cathepsin H concentrations were elevated in all asthmatic patients, concentrations of both stefins were decreased in steroid-independent asthmatics, and stefin A concentrations were increased in steroid-dependent asthmatics before therapy. The effect of methylprednisolone treatment was demonstrated on decreased cathepsin B and increased cathepsin L concentrations in post-therapy serum samples. On the other hand, cyclosporin A treatment led to increased concentrations of cathepsins H and L. However, concentrations of stefins A and B were unaffected.

CONCLUSIONS

This study associated alterations in balance of serum cysteine proteinases and their inhibitors in asthmatic patients, which has raised the possibility of their involvement in asthma pathogenesis. Validated rhythms of cathepsins and stefins in asthmatic sera exhibited temporal differences, which are too small to influence the time of sampling for their quantitative measurement over the course of a day.

Increased concentrations of cathepsin D in peritoneal fluid from women with endometriosis

To assess the release of the proteolytic enzyme cathepsin D in endometriosis, concentrations in peritoneal fluid and serum were measured by ELISA in 54 women with (n = 33) and without (n = 21) endometriosis. Surgery was scheduled in either the proliferative or secretory phase of the menstrual cycle. The concentrations of cathepsin D in the peritoneal fluid were markedly elevated in the endometriosis patients (median 58 ng/ml, interquartile range 0-166 ng/ml) as compared to the controls (5 ng/ml, 0-86 ng/ml), especially in women with late stage disease (n = 19, stages III/IV) and in those not undergoing gonadotrophin-releasing hormone (GnRH) agonist therapy (n = 15). No significant difference was determined in cathepsin D concentrations of the serum from women with and without endometriosis. We conclude that cathepsin D is an important factor that may contribute to the pathogenesis of endometriosis, possibly by promoting digestion of extracellular matrix proteins. These results have implications for the therapeutic efficacy of GnRH agonists.

Angiogenesis and cathepsin expression are prognostic factors in pancreatic adenocarcinoma after curative resection

BACKGROUND

Curative resection of pancreatic adenocarcinoma is the only clinical parameter related to a favorable prognosis while other clinicopathological parameters fail. To evaluate whether angiogenesis, vascular endothelial growth factor (VEGF) or certain tumor proteases, e.g., cathepsin B (CTSB) and L (CTSL), are factors of prognostic relevance, we investigated their expression in patients with long- and short-term survival after curative resection (RO) because of pancreatic adenocarcinoma.

METHODS

Twenty-nine tissue samples from patients with adenocarcinoma of the pancreas were examined. The patients were selected in a long-term survival group with a survival > or = 24 mo (n = 18) and a shortterm survival group of patients, who died within 8 mo after surgery because of their malignancy (n = 11). The microvessel quantification was performed immunohistochemically using a monoclonal anti-CD34 antibody. VEGF, CTSB, and CTSL expressions was studied using polyclonal antibodies (PAbs).

RESULTS

The median microvessel density (MVD) was 75 (range 39-182). MVD correlated significantly with the survival time after surgery (p = 0.0132) but not with clinicopathological parameters. In cancer cells, VEGF was positive in 82.8% and showed significant correlation with the MVD (p = 0.0002) and survival time (p = 0.0395). Positive immunoreactivity could be obtained for 96.5% for CTSB and 84.2% for CTSL. Expression of both proteases correlated significantly with the survival time after surgery (CTSB p = 0.0002, CTSL p = 0.0001). Furthermore, CTSB expression correlated with invasion of the perineural space. Thus, a short postoperative survival correlated with a high MVD, and highly expressed VEGF, CTSB, and CTSL. No significant correlation between MVD, VEGF, as well as CTSL and clinicopathological parameters was found. For routinely assessed markers (e.g., TNM-stage, UICC-stage, and so on) no significant correlation with survival time was found in this small group of patients.

CONCLUSION

These findings indicate that the MVD, VEGF, CTSB, and CTSL are prognostic factors after curative resection, whereas other parameters (TNM, UICC, and so on) failed to show prognostic relevance in our group of patients. Furthermore, the correlation between MVD and VEGF underlines the importance of this growth factor for angiogenesis and tumor growth. The correlation between CTSB and perineural invasion demonstrates the involvement of cathepsins in local tumor invasion.

Alterations in cathepsin H activity and protein patterns in human colorectal carcinomas

Our analyses of cathepsin H activity levels and protein forms in human colorectal cancers compared to matched control mucosa support the concept that altered proteinase expression patterns may reflect both cancer stage and site. Cathepsin H-specific activity was significantly increased in colorectal cancers compared to control mucosa (P = 0.003; n = 77). Highest specific activities and cancer/normal ratios (C/N) for activity were measured in Dukes' B and C stage carcinomas, cancers involved in local spread and invasion to lymph nodes. In contrast, cathepsin B and L activities analysed in the same paired extracts had been shown to be most frequently elevated in earlier stage carcinomas (Dukes' A and B), confirming that cathepsin H demonstrates a distinct pattern of expression during colorectal cancer progression. Although cathepsin H activities were most commonly elevated in Dukes' C cancers at all colon sites, both specific activity and C/N ratios were significantly higher for cancers of the left colon compared to other colon locations. A subset of 43 paired extracts analysed on Western blots also revealed consistent changes in cathepsin H protein forms in cancers. Normal mucosa typically showed a strong protein doublet at 31 and 29 kDa while cancers demonstrated decreased expression or total loss of the 31 kDa protein (90% of cases), equal or increased expression of the 29-kDa protein (67% of cases) and the new appearance or up-regulation of a cathepsin H band at 22 kDa (78% of cases). C/N ratios for cathepsin H enzyme activity correlated significantly with C/N ratios for the 29 kDa mature single-chain protein form (P < 0.001), with increased activity most commonly associated with elevated expression of 29-kDa cathepsin H but also with up-regulation of the 22-kDa band, suggesting a shift to more fully processed, mature active cathepsin H protein forms in cancers. Changes in cathepsin H expression were also detected by immunohistochemistry as elevated cathepsin H staining in tumour epithelial cells.

Immunochemical analysis of cathepsin B in lung tumours: an independent prognostic factor for squamous cell carcinoma patients

In order to evaluate the possible role of the proteolytic enzyme cathepsin B (cath B) in human non-small cell lung cancer (NSCLC) we examined cath B concentrations (cath B(C)) and activities (cath B(A)) in homogenates of 127 pairs of lung tumour tissues and corresponding non-tumourous lung parenchyma. Total cath B activity (cath B(AT)) and enzymatic activity of the fraction of cath B, which is stable and active at pH 7.5 (cath B(A7.5)) were determined by a fluorogenic assay using synthetic substrate Z-Arg-Arg-AMC. The immunostaining pattern of cath B was determined in 239 lung tumour tissue sections, showing the presence of the enzyme in tumour cells (cath B(T-I)) and in tumour-associated histiocytes (cath B(H-I)). The median levels of cath B(AT), cath B(A7.5) and cath B(C) were 5.6-, 3.2- and 9.1-fold higher (P < 0.001), respectively, in tumour tissue than in non-tumourous lung parenchyma. Out of 131 tissue sections from patients with squamous cell carcinoma (SCC), 59.5% immunostained positively for cath B, while among the 108 adenocarcinoma (AC) patients 48.2% of tumours showed a positive reaction. There was a strong relationship between the levels of cath B(AT), cath B(A7.5), cath B(C) and cath B(T-I) in the primary tumours and the presence of lymph node metastases. Significant correlation with overall survival was observed for cath B(T-I) and cath B(A7.5) (P < 0.01 and P < 0.05, respectively) in patients suffering from SCC. In these patients positive cath B in tumour cells (cath B(T-I)) and negative cath B in histiocytes (cath B(H-I)) indicated significantly shorter survival rate compared with patients with negative cath B(T-I) and positive cath B(H-I) (P < 0.0001). In contrast, in AC patients, both, positive cath B(T-I) and positive cath B(H-I), indicated poor survival probability (P < 0.014). From these results we conclude that the proteolytic enzyme cath B is an independent prognostic factor for overall survival of patients suffering from SCC of the lung.

An active zymogen: unravelling the mystery of tissue-type plasminogen activator

In contrast to almost all other proteinases, human tissue-type plasminogen activator (tPA) is also proteolytically active in its zymogen or single-chain form. The closely related plasminogen activator isolated from vampire bat saliva (vPA) acts exclusively in the single-chain form, lacking the requisite cleavage site for proteolytic activation. Recent structural studies on the proteolytic domains of vPA and human tPA in two- and single-chain forms reveal the mechanism of this anomalous activity. The PA-catalyzed proteolytic conversion of plasminogen to plasmin, responsible for the initiation of fibrinolysis, is fibrin-dependent; comparative structural analysis of the plasminogen activators provides clues as to the role of fibrin as cofactor.