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

Nuclear Localization of Heme Oxygenase-1 in Pathophysiological Conditions: Does It Explain the Dual Role in Cancer?

Heme Oxygenase-1 (HO-1) is a type II detoxifying enzyme that catalyzes the rate-limiting step in heme degradation leading to the formation of equimolar quantities of carbon monoxide (CO), free iron and biliverdin. HO-1 was originally shown to localize at the smooth endoplasmic reticulum membrane (sER), although increasing evidence demonstrates that the protein translocates to other subcellular compartments including the nucleus. The nuclear translocation occurs after proteolytic cleavage by proteases including signal peptide peptidase and some cysteine proteases. In addition, nuclear translocation has been demonstrated to be involved in several cellular processes leading to cancer progression, including induction of resistance to therapy and enhanced metastatic activity. In this review, we focus on nuclear HO-1 implication in pathophysiological conditions with special emphasis on malignant processes. We provide a brief background on the current understanding of the mechanisms underlying how HO-1 leaves the sER membrane and migrates to the nucleus, the circumstances under which it does so and, maybe the most important and unknown aspect, what the function of HO-1 in the nucleus is.

Ab locks for improving the selectivity and safety of antibody drugs

Monoclonal antibodies (mAbs) are a major targeted therapy for malignancies, infectious diseases, autoimmune diseases, transplant rejection and chronic inflammatory diseases due to their antigen specificity and longer half-life than conventional drugs. However, long-term systemic antigen neutralization by mAbs may cause severe adverse events. Improving the selectivity of mAbs to distinguish target antigens at the disease site from normal healthy tissue and reducing severe adverse events caused by the mechanisms-of-action of mAbs is still a pressing need. Development of pro-antibodies (pro-Abs) by installing a protease-cleavable Ab lock is a novel and advanced recombinant Ab-based strategy that efficiently masks the antigen binding ability of mAbs in the normal state and selectively "turns on" the mAb activity when the pro-Ab reaches the proteolytic protease-overexpressed diseased tissue. In this review, we discuss the design and advantages/disadvantages of different Ab lock strategies, focusing particularly on spatial-hindrance-based and affinity peptide-based approaches. We expect that the development of different masking strategies for mAbs will benefit the local reactivity of mAbs at the disease site, increase the therapeutic efficacy and safety of long-term treatment with mAbs in chronic diseases and even permit scientists to develop Ab drugs for formerly undruggable targets and satisfy the unmet medical needs of mAb therapy.

Activatable Photodynamic Therapy with Therapeutic Effect Prediction Based on a Self-correction Upconversion Nanoprobe

Though emerging as a promising therapeutic approach for cancers, the crucial challenge for photodynamic therapy (PDT) is activatable phototoxicity for selective cancer cell destruction with low "off-target" damage and simultaneous therapeutic effect prediction. Here, we design an upconversion nanoprobe for intracellular cathepsin B (CaB)-responsive PDT with in situ self-corrected therapeutic effect prediction. The upconversion nanoprobe is composed of multishelled upconversion nanoparticles (UCNPs) NaYF₄:Gd@NaYF₄:Er,Yb@NaYF₄:Nd,Yb, which covalently modified with an antenna molecule 800CW for UCNPs luminance enhancement under NIR irradiation, photosensitizer Rose Bengal (RB) for PDT, Cy3 for therapeutic effect prediction, and CaB substrate peptide labeled with a QSY7 quencher. The energy of UCNPs emission at 540 nm is transferred to Cy3/RB and eventually quenched by QSY7 via two continuous luminance resonance energy transfer processes from interior UCNPs to its surface-extended QSY7. The intracellular CaB specifically cleaves peptide to release QSY7, which correspondingly activates RB with reactive oxygen species (ROS) generation for PDT and recovers Cy3 luminance for CaB imaging. UCNPs emission at 540 nm remains unchanged during the peptide cleavage process, which is served as an internal standard for Cy3 luminance correction, and the fluorescence intensity ratio of Cy3 over UCNPs (FI583/FI540) is measured for self-corrected therapeutic effect prediction. The proposed self-corrected upconversion nanoprobe implies significant potential in precise tumor therapy.

Prognostic and therapeutic relevance of cathepsin B in pediatric acute myeloid leukemia

AML, the second most common childhood leukemia is also one of the deadliest cancers. High mortality rate in AML is due to high incidence of relapse after complete remission with chemotherapy and inadequate prognostic assessment of patients. Moreover, there is dearth of therapeutic targets for treatment of this malignancy. Previous pilot study (n = 24) by our group revealed strong association between cathepsin B (CTSB) overexpression in peripheral blood mononuclear cells (PBMCs) and poor survival outcome in pediatric AML patients. To further explore the clinical utility and role of this protease in pediatric AML, we measured its enzymatic activity and mRNA expression in PBMCs as well as bone marrow mononuclear cells (BMMCs) of patients (n = 101) and PBMCs of healthy controls. Our results revealed elevated CTSB activity (P < 0.01) and overexpression of its mRNA (P < 0.01) in AML patients. Interestingly CTSB in BMMCs of patients emerged as an independent prognostic marker when compared with other known risk factors. Moreover, chemical inhibition of CTSB activity compromised survival, and induced apoptosis in an AML cell line THP-1. We further demonstrate the inhibition of CTSB activity by chemotherapeutic agent doxorubicin in these cells. Docking and simulation studies suggested the binding of doxorubicin to CTSB with higher affinity than its known specific inhibitor CA-074 Me, thereby indicating that cell death induced by this drug may at least partly be mediated by CTSB inhibition. CTSB, therefore, may serve as a prognostic marker and an attractive chemotherapeutic target in pediatric AML.

Fisetin Suppresses the Proliferation and Metastasis of Renal Cell Carcinoma through Upregulation of MEK/ERK-Targeting CTSS and ADAM9

Fisetin, a natural flavonoid, is known to have anticarcinogenic effects against several cancers, but its role in mediating renal cell carcinoma (RCC) progression has not been delineated. Cell viability, cytotoxicity, and cell cycle distribution were measured using the 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and propidium iodide staining with flow cytometry. The in vitro migration and invasion assay was used to examine in vivo cell migration and invasion. Human protease antibody array analysis was conducted with cell migration/invasion-related proteins. Western blotting and quantitative reverse transcription polymerase chain reaction were used for assessing protein expression related to the cell cycle, cell invasion, and mitogen-activated protein kinase (MAPK) signaling pathway. We found that fisetin significantly inhibited cell viability through cell cycle arrest in the G2/M phase, in addition to downregulating cyclin D1 and upregulating p21/p27. Fisetin inhibited the migration and invasion of human RCC cells through the downregulation of CTSS and a disintegrin and metalloproteinase 9 (ADAM9). Fisetin also upregulated ERK phosphorylation in 786-O and Caki-1 cells. Furthermore, treatment with a MEK inhibitor (UO126) reduced the inhibitory effects of fisetin on the metastasis of RCC cells through the ERK/CTSS/ADAM9 pathway. Fisetin inhibits proliferation and metastasis of RCC cells by downregulating CTSS and ADAM9 through the MEK/ERK signaling pathway. These findings indicate that fisetin is a promising antitumor agent against RCC.

Fluorescent probes towards selective cathepsin B detection and visualization in cancer cells and patient samples

Highly selective fluorescent activity-based probe for the visualization of cathepsin B in cancer cells.

Human cysteine cathepsins constitute an 11-membered family of proteases responsible for degradation of proteins in cellular endosomal–lysosomal compartments as such, they play important roles in antigen processing, cellular stress signaling, autophagy, and senescence. Moreover, for many years these enzymes were also linked to tumor growth, invasion, angiogenesis and metastasis when upregulated. Individual biological roles of each cathepsin are difficult to establish, because of their redundancy and similar substrate specificities. Selective chemical tools that enable imaging of individual cathepsin activities in living cells, tumors, and the tumor microenvironment may provide a better insight into their functions. In this work, we used HyCoSuL technology to profile the substrate specificity of human cathepsin B. The use of unnatural amino acids in the substrate library enabled us to uncover the broad cathepsin B preferences that we utilized to design highly-selective substrates and fluorescent activity-based probes (ABPs). We further demonstrated that Cy5-labeled MP-CB-2 probe can selectively label cathepsin B in eighteen cancer cell lines tested, making this ABP highly suitable for other biological setups. Moreover, using Cy5-labelled MP-CB-2 we were able to demonstrate by fluorescence microscopy that in cancer cells cathepsins B and L share overlapping, but not identical subcellular localization.

Cysteine cathepsins as a prospective target for anticancer therapies-current progress and prospects

Cysteine cathepsins (CTS), being involved in both physiological and pathological processes, play an important role in the human body. During the last 30 years, it has been shown that CTS are highly upregulated in a wide variety of cancer types although they have received a little attention as a potential therapeutic target as compared to serine or metalloproteinases. Studies on the increasing problem of neoplastic progression have revealed that secretion of cell-surface- and intracellular cysteine proteases is aberrant in tumor cells and has an impact on their growth, invasion, and metastasis by taking part in tumor angiogenesis, in apoptosis, and in events of inflammatory and immune responses. Considering the role of CTS in carcinogenesis, inhibition of these enzymes becomes an attractive strategy for cancer therapy. The downregulation of natural CTS inhibitors (CTSsis), such as cystatins, observed in various types of cancer, supports this claim. The intention of this review is to highlight the relationship of CTS with cancer and to present illustrations that explain how some of their inhibitors affect processes related to neoplastic progression.

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.

Development of a Novel Enzyme-Linked Immunosorbent Assay Targeting a Neo-Epitope Generated by Cathepsin-Mediated Turnover of Type III Collagen and Its Application in Chronic Obstructive Pulmonary Disease

A high level of extracellular matrix (ECM) turnover characterizes several lung diseases with fibrotic features. Type III collagen is one of the most abundant collagens in lung parenchyma, and cathepsins play a role in lung pathology, being responsible for tissue remodeling. In this study, we explore the diagnostic features of neo-epitope fragments of type III collagen generated by cathepsins that could reflect the pathological tissue turnover in patients with different diseases. A novel enzyme-linked immunosorbent assay (ELISA) measuring cathepsins B, L, S and K -generated type III collagen fragments (C3C) was developed for assessment in serum and plasma. The assay was biologically validated in serum from patients with chronic obstructive pulmonary disease (COPD). Serological levels of C3C were significantly elevated in patients with COPD compared to healthy controls (p = 0.0006). Levels of C3C in serum and heparin plasma of COPD patients had a highly significant correlation (R² = 0.86, p<0.0001). The data suggests that the C3C fragment is elevated in patients with COPD compared to healthy controls.

Hormonal-receptor positive breast cancer: IL-6 augments invasion and lymph node metastasis via stimulating cathepsin B expression

Hormonal-receptor positive (HRP) breast cancer patients with positive metastatic axillary lymph nodes are characterized by poor prognosis and increased mortality rate. The mechanisms by which cancer cells invade lymph nodes have not yet been fully explored. Several studies have shown that expression of IL-6 and the proteolytic enzyme cathepsin B (CTSB) was associated with breast cancer poor prognosis. In the present study, the effect of different concentrations of recombinant human IL-6 on the invasiveness capacity of HRP breast cancer cell line MCF-7 was tested using an in vitro invasion chamber assay. The impact of IL-6 on expression and activity of CTSB was also investigated. IL-6 treatment promoted the invasiveness potential of MCF-7 cells in a dose-dependent manner. Furthermore, MCF-7 cells displayed elevated CTSB expression and activity associated with loss of E-cadherin and upregulation of vimentin protein levels upon IL-6 stimulation. To validate these results in vivo, the level of expression of IL-6 and CTSB in the carcinoma tissues of HRP-breast cancer patients with positive and negative axillary metastatic lymph nodes (pLNs and nLNs) was assessed. Western blot and immunohistochemical staining data showed that expression of IL-6 and CTSB was higher in carcinoma tissues in HRP-breast cancer with pLNs than those with nLNs patients. ELISA results showed carcinoma tissues of HRP-breast cancer with pLNs exhibited significantly elevated IL-6 protein levels by approximately 2.8-fold compared with those with nLNs patients (P < 0.05). Interestingly, a significantly positive correlation between IL-6 and CTSB expression was detected in clinical samples of HRP-breast cancer patients with pLNs (r = 0.78, P < 0.01). Collectively, this study suggests that IL-6-induced CTSB may play a role in lymph node metastasis, and that may possess future therapeutic implications for HRP-breast cancer patients with pLNs. Further studies are necessary to fully identify IL-6/CTSB axis in different molecular subtypes of breast cancer.

Cysteine cathepsin proteases: regulators of cancer progression and therapeutic response

Cysteine cathepsin protease activity is frequently dysregulated in the context of neoplastic transformation. Increased activity and aberrant localization of proteases within the tumour microenvironment have a potent role in driving cancer progression, proliferation, invasion and metastasis. Recent studies have also uncovered functions for cathepsins in the suppression of the response to therapeutic intervention in various malignancies. However, cathepsins can be either tumour promoting or tumour suppressive depending on the context, which emphasizes the importance of rigorous in vivo analyses to ascertain function. Here, we review the basic research and clinical findings that underlie the roles of cathepsins in cancer, and provide a roadmap for the rational integration of cathepsin-targeting agents into clinical treatment.

Structure and expression of a cysteine proteinase gene from Spodoptera litura and its response to biocontrol fungus Nomuraea rileyi

Cysteine proteinases (Cyps) play vital roles in many biological processes, including physiological and pathological reactions. In the present study, we cloned a full cDNA of SlCyp, encoding a 344-amino-acid protein from Spodoptera litura. The putative amino acid sequence shared >75% identity with Cyps from other insects. A phylogenetic analysis revealed that SlCyp is closely related to other known lepidopteran Cyps. Real-time PCR and Western blotting analyses showed that SlCyp is induced by Nomuraea rileyi infection in all the tissues tested. The strongest SlCyp mRNA and protein expression was found in haemocytes, followed by the fat bodies, of unchallenged and N. rileyi-challenged S. litura. A time-course analysis showed that SlCyp mRNA and protein expression levels were upregulated in the haemocytes and fat bodies by N. rileyi infection. Upon N. rileyi infection, the proteolytic activities of SlCyp were also significantly higher in the haemolymph than in normal or phosphate-buffered-saline-challenged controls. These results suggest that SlCyp plays an important role in the innate immunity of S. litura in response to N. rileyi. SlCyp mRNA and protein expression and activities were also elevated during sixth-instar moulting and metamorphosis. Knocking down SlCyp transcripts with double-stranded RNA interference caused prepupal, pupal, and adult phenotypic changes, and SlCyp-silenced mutant larvae displayed a significantly lower survival rate after N. rileyi infection. These facts suggest that SlCyp plays a significant role in resisting N. rileyi infection and an essential role in larval development. Our data should facilitate the development of techniques for S. litura control.

Monocytes conditioned media stimulate fibronectin expression and spreading of inflammatory breast cancer cells in three-dimensional culture: A mechanism mediated by IL-8 signaling pathway

Background

Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer characterized by invasion of carcinoma cells into dermal lymphatic vessels where they form tumor emboli over expressing adhesion molecule E-cadherin. Although invasion and metastasis are dynamic processes controlled by complex interaction between tumor cells and microenvironment the mechanisms by which soluble mediators may regulate motility and invasion of IBC cells are poorly understood. The present study investigated the effect of media conditioned by human monocytes U937 secreted cytokines, chemokines and growth factors on the expression of adhesion molecules E-cadherin and fibronectin of human IBC cell line SUM149. Furthermore, cytokines signaling pathway involved were also identified.

Results

U937 secreted cytokines, chemokines and growth factors were characterized by cytokine antibody array. The major U937 secreted cytokines/chemokines were interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1/CCL2). When SUM149 cells were seeded in three dimensional (3D) models with media conditioned by U937 secreted cytokines, chemokines and growth factors; results showed: 1) changes in the morphology of IBC cells from epithelial to migratory spindle shape branched like structures; 2) Over-expression of adhesion molecule fibronectin and not E-cadherin. Further analysis revealed that over-expression of fibronectin may be mediated by IL-8 via PI3K/Akt signaling pathway.

Conclusion

The present results suggested that cytokines secreted by human monocytes may promote chemotactic migration and spreading of IBC cell lines. Results also indicated that IL-8 the major secreted cytokine by U937 cells may play essential role in fibronectin expression by SUM149 cells via interaction with IL-8 specific receptors and stimulation of PI3K/Akt signaling pathway.

Cathepsin D messenger RNA is downregulated in human lung cancer

OBJECTIVES

Lysosomal proteases cathepsins B and D (CB and CD) play a significant part in cancer progression. For many oncological diseases protein expression levels of CB and CD have been investigated and correlations with tumour characteristics revealed. Meanwhile, there is very little information concerning mRNA expression level.

METHODS

In the present work, data about mRNA levels of CB and CD in human lung cancer was obtained using reverse transcription followed by real-time polymerase chain reaction.

RESULTS

For the first time CD and CB mRNA in human lung cancer tumours was quantified. It was shown that CB and CD mRNA levels do not correlate with any tumour characteristics. However, in most analysed tumours, expression of CD mRNA was downregulated compared with adjacent normal tissue (p <0.0003).

CONCLUSIONS

The data obtained indicate CD mRNA as a potential lung cancer marker.

A cathepsin L-like proteinase is involved in moulting and metamorphosis in Helicoverpa armigera

Holometabolous insects undergo larval moulting and metamorphosis within their life cycle. A cDNA encoding the cathepsin L-like proteinase Ha-cathL has been cloned from Helicoverpa armigera. It has a sequence of 1826 bp and encodes a 550-residue protein with a molecular mass of 63 kDa. Northern blot analysis indicated that Ha-cathL is specifically expressed in haemocytes, with increased expression during larval moulting and metamorphosis. In vivo experimentation revealed that Ha-cathL is up-regulated by 20-hydroxyecdysone. Meanwhile, in situ hybridization and immunocytochemistry revealed that Ha-cathL mRNA is mainly expressed in granulocytes and plasmatocytes. Knock down of cathepsin L by RNA interference results in larvae death before pupation or the formation of a chimeric pupa containing a larval head and thorax, abnormal wings and the pupal abdomen. The reason for this is that the affected haemocytes cannot become granulated, and therefore cannot participate in fat body remodelling and wing development. These facts suggest that Ha-cathL is involved in larval moulting and metamorphosis by participating in the functioning of haemocytes.

Cathepsin B is a target of Hedgehog signaling in pancreatic cancer

This study investigated the influence of cathepsin B (CATB), a downstream target of Hedgehog (Hh) signaling, in pancreatic cancer. Cyclopamine (Hh signal inhibitor) suppressed expression of Shh, as well as Hh-induced transcription factor Gli1, and induced apoptosis in Shh-positive pancreatic cancer cell line (PANC-1). Microarray analysis revealed CATB as a gene downregulated by Hh. Cyclopamine reduced CATB protein and mRNA levels. Cyclopamine or CATB inhibitor reduced PANC-1 cell invasiveness (P<0.05). CATB expression in human pancreatic cancer tissues tended to correlate with Shh expression (P=0.053). Conclusively, Hh targets CATB and Hh signaling through CATB might influence pancreatic cancer cell invasiveness.

Biochemistry and Clinical Role of Human Cystatin C

Low molecular-mass plasma proteins play a key role in health and disease. Cystatin C is an endogenous cysteine proteinase inhibitor belonging to the type 2 cystatin superfamily. The mature, active form of human cystatin C is a single non-glycosylated polypeptide chain consisting of 120 amino acid residues, with a molecular mass of 13,343-13,359 Da, and containing four characteristic disulfide-paired cysteine residues. Human cystatin C is encoded by the CST3 gene, ubiquitously expressed at moderate levels. Cystatin C monomer is present in all human body fluids; it is preferentially abundant in cerebrospinal fluid, seminal plasma, and milk. Cystatin C L68Q variant is an amyloid fibril-forming protein with a high tendency to dimerize. It forms self-aggregates with massive amyloid deposits in the brain arteries of young adults, leading to lethal cerebral hemorrhage. The main catabolic site of cystatin C is the kidney: more than 99% of the protein is cleared from the circulation by glomerular ultrafiltration and tubular reabsorption. The diagnostic value of cystatin C as a marker of kidney dysfunction has been extensively investigated in multiple clinical studies on adults, children, and in the elderly. In almost all the clinical studies, cystatin C demonstrated a better diagnostic accuracy than serum creatinine in discriminating normal from impaired kidney function, but controversial results have been obtained by comparing this protein with other indices of kidney disease, especially serum creatinine-based equations. In this review, we present and discuss most of the available data from the literature, critically reviewing conclusions and suggestions for the use of cystatin C in clinical practice. Despite the multitude of clinical data in the literature, cystatin C has not been widely used, perhaps because of a combination of factors, such as a general diffidence among clinicians, the absence of definitive cut-off values, conflicting results in clinical studies, no clear evidence on when and how to request the test, the poor commutability of results, and no accurate examination of costs and of its routine use in a stat laboratory.

Dual contrasting roles of cysteine cathepsins in cancer progression: apoptosis versus tumour invasion

Cysteine cathepsins have been known for a long time to play an important role in cancer progression and metastasis. Several studies have proposed the concept of anti-cathepsin therapy in cancer treatment. On the other hand, cysteine cathepsins have been recently found to play a role in tumour cell death through mediation of apoptosis. The purpose of this mini-review is therefore to provide an insight into the mechanisms by which cysteine cathepsins modulate apoptosis and/or participate in tumour invasion, and to evaluate the impact of these enzymes on both tumour progression and development of potential strategies for cancer treatment.

Increased carcinogenic potential of myeloid tumor cells induced by aberrant TGF-beta1-signaling and upregulation of cathepsin B

The TGF-beta signaling pathways are implicated in cancer. Cysteine cathepsins can contribute to the carcinogenic potential of tumor cells. The aim of this study was to investigate the regulation of cysteine cathepsin expression by TGF-beta1 and the functional implications in tumor cells. We found an upregulation of cathepsin B (CathB, 2- to 5-fold) in different myeloid tumor cells (THP-1, MonoMac-1, MonoMac-6) after incubation with TGF-beta1. No upregulation was found in monocytes, and there was suppression of CathB expression in epithelial tumor cells (A549). Increased cathepsin B activity led to enhanced carcinogenic potential, which was reflected by increased migration and invasion of the cells and resistance to inhibitor-induced apoptosis. Analysis of the TGF-beta signaling pathways showed no alterations in TGF-beta/BMP receptor expression or SMAD2/3 phosphorylation, and no influence of MAP kinase pathways. However, a reduction in SMAD1 expression was detected. The lack of BMP action on cysteine cathepsin expression in myeloid tumor cells, but not in epithelial tumor cells, suggests a defect in the Smad1/Smad5 pathway. We located a related TGF-beta1-responsive element within the first intron of the CathB gene. In conclusion, alterations in the TGF-beta1 signaling pathway lead to upregulation of CathB, which contributes to the carcinogenic potential of tumor cells.

Overexpression of stefin A in human esophageal squamous cell carcinoma cells inhibits tumor cell growth, angiogenesis, invasion, and metastasis

PURPOSE

Evidence is accumulating that an inverse correlation exists between stefin A level and malignant progression. The aim of this study is to investigate the role of stefin A in human esophageal squamous cell carcinoma cells and to evaluate the possibility of stefin A for cancer therapy.

EXPERIMENTAL DESIGN

We stably transfected stefin A cDNA into human EC9706 or KYSE150 esophageal squamous cell carcinoma cells. Subsequently, we evaluated the effect of stefin A overexpression on cell growth, cathepsin B activity, cell motility and invasion, tumor growth, and metastasis. Immunoanalysis was done to assess the expression of factor VIII and to support the localization of stefin A and cathepsin B. We also evaluated the effect of CA074Me, a selective membrane-permeant cathepsin B inhibitor.

RESULTS

Both transfection of stefin A and treatment with 10 micromol/L CA074Me significantly reduced cathepsin B activity and inhibited the Matrigel invasion. Combination of both further reduced cathepsin B activity and inhibited the Matrigel invasion. Overexpression of stefin A delayed the in vitro and in vivo growth of cells and significantly inhibited lung metastasis compared with 50% of lung metastasis in xenograft mice from EC9706 or empty vector cells. Transfection with stefin A showed a dramatic reduction of factor VIII staining in the tumors of xenograft mice.

CONCLUSIONS

Our data strongly indicate that stefin A plays an important role in the growth, angiogenesis, invasion, and metastasis of human esophageal squamous cell carcinoma cells and suggest that stefin A may be useful in cancer therapy.

Cysteine cathepsins in human cancer

Proteases play causal roles in the malignant progression of human tumors. This review centers on the roles in this process of cysteine cathepsins, i.e., peptidases belonging to the papain family (C1) of the CA clan of cysteine proteases. Cysteine cathepsins, most likely along with matrix metalloproteases (MMPs) and serine proteases, degrade the extracellular matrix, thereby facilitating growth and invasion into surrounding tissue and vasculature. Studies on tumor tissues and cell lines have shown changes in expression, activity and distribution of cysteine cathepsins in numerous human cancers. Molecular, immunologic and pharmacological strategies to modulate expression and activity of cysteine cathepsins have provided evidence for a causal role for these enzymes in tumor progression and invasion. Clinically, the levels, activities and localization of cysteine cathepsins and their endogenous inhibitors have been shown to be of diagnostic and prognostic value. Understanding the roles that cysteine proteases play in cancer could lead to the development of more efficacious therapies.

Melanoma heterogeneity: differential, invasive, metastatic properties and profiles of cathepsin B, D and L activities in subclones of the B16F10-NEX2 cell line

Tumour cell lines and in vivo growing tumours are heterogeneous, comprising different cell clones. To understand why some cells primarily invade a tissue, while others are more apt to metastasize, several clones from the established B16F10-Nex2 cell line were isolated and 10 viable cells of each clone were injected intravenously into C57Bl/6 and Balb/c mice. Two cell clones (Nex2B and Nex2D) showed contrasting metastatic abilities. Clone 2D rather than clone 2B colonized the lungs of both mice after intravenous injection. Surprisingly, clone 2B grew more rapidly than 2D after subcutaneous implantation, significantly reducing the survival of injected mice. Clearly, dissociation between subcutaneous growth and metastatic ability was observed in clones from the same tumour cell lineage. Clone Nex2B continuously released proteolytic activity, including cathepsin B, and showed a greater capacity to invade Matrigel than clone Nex2D. Clone Nex2D accumulated cathepsins B, D and L intracellularly and released a moderate proteolytic activity in vitro that was inhibited with the time of incubation. E-64-treated Nex2B cells injected subcutaneously showed a significant delay in tumour development and increased survival of challenged animals. A similar result was obtained on treatment of clone 2B with chagasin, a cysteine proteinase inhibitor from Trypanosoma cruzi, even at 2 microM. Clone Nex2D was less sensitive to pretreatment with inhibitors of cysteine proteases for tumour development in vivo. Our results suggest that, in a tumour cell population, cells dissociate into metastatic and non-metastatic subtypes, and that release or accumulation of cathepsins can be a differential trait of these cells.

Expression of Cathepsin B and microvascular density increases with higher grade of astrocytomas

Samples were taken from supratentorial gliomas border and normal brain autopsy which were divided into four groups, these including eight cases normal brain tissues, 30 cases of astrocytomas, 25 cases of anaplastic astrocytomas and 22 cases of glioblastomas. Cathepin B (CB) expression and microvessel density (MVD) were determined with immunohistochemical studies. Staining results of CB was scored according to the percentage of positive cells, graded as negative (-), weak (+), moderate (++), and strong (+ + +). MVD was analyzed by Weidner's revised technique. CB positive staining was negative in eight cases of normal brain tissue. Only 9 out of 30 cases of astrocytomas showed a low percentage of positive cells that were stained in a light, diffuse cytoplasmic pattern (score +). Twenty-two out of 35 cases of anaplastic astrocytomas showed positive light, granular staining pattern, it including five samples (score +), and 17 samples (score + +). In contrast, all 22 cases of glioblastomas were stained all, and it was present in a course, granular staining pattern with an intensity of score (+ +) of two sample, and score (+ + +) of 20 samples. Positive staining tumor cells were found in extracellular matrix (ECM), basement membrane (BM), and the endothelial cells of blood vessels were also positive stained. Along with elevating glioma grade, CB expression and MVD value were both increased. Therefore, it showed MVD value was positive correlated with expression of CB. It highly suggested that CB and angiogenesis plays an important role in glioma progression.

Modulation of cystatin C expression impairs the invasive and tumorigenic potential of human glioblastoma cells

Increases in the abundance of cathepsin B transcript and protein with increased tumor grade and changes in subcellular localization and activity of this enzyme. We observed progressive reductions in levels of the protease inhibitor cystatin C, an inhibitor of cathepsin B with corresponding increases in the malignancy of glioma cell lines, implying an inverse correlation between cystatin C and tumor grade. To investigate the role of cystatin C in the invasion of brain tumor cells, we stably transfected SNB19 glioblastoma cells with either a 0.4-kb cDNA construct of human cystatin C in the sense orientation or an empty vector. Clones expressing sense-cystatin C cDNA had higher cystatin C mRNA and protein levels than did control cells. Sense-transfected cells were also markedly less invasive than control cells in a Matrigel invasion assay and in a coculture assay of SNB19 spheroids and fetal rat brain aggregates. Finally, the sense-transfected cells did not form tumors in nude mice upon intracerebral injection. These results strongly implicate cystatin C in the invasiveness of human glioblastoma cells and suggest that sense transcripts of cystatin C may prove useful in cancer therapy.

Molecular cloning and characterization of the cathepsin B-like proteinase from the cotton boll worm, Helicoverpa armigera

An enzyme purified from the ovaries of Helicoverpa armigera, as an active form with molecular mass of 30 kDa on SDS-PAGE, was identified as a cysteine proteinase because it could be inhibited by E-64, a specific inhibitor of cysteine proteinase, and required reducing conditions for activity. This enzyme was further identified as a cathepsin B-like cysteine proteinase by partial amino acid sequencing. A cDNA encoding this proteinase was cloned from H. armigera, using degenerate primers and RACE techniques. Results of Northern blots indicated that the mRNA encoding the proteinase was transcribed in the ovaries, the fat bodies of female and male adults, pupae and in the larvae. No mRNA was detected from the larval epidermis or from the midgut. Hence, transcription of the cathepsin B-like cysteine proteinase from H. armigera was tissue-specific, but not gender- or developmental stage-specific. However, proteolytic activities were only detected from ovaries, and adult female and male fat bodies. No activity was observed from pupal and larval fat bodies, from the larval epidermis or from the midgut. Only one form of mRNA of approximately 1100 bases was detected, and in situ hybridization showed that the transcripts were distributed in the adult female fat bodies, follicular cells and the oocytes. Since the proteinase expressed in ovaries was able to degrade vitellin in vitro, it may be involved in the degradation of vitellin during embryonic development.

Toward a more complete recognition of immunoreactive antigens in squamous cell lung carcinoma

There is very limited knowledge about the antibody response against tumor-expressed antigens in lung cancer. To arrive at a more complete picture of lung cancer antigens, we generated 2 cDNA libraries from squamous cell lung carcinoma and isolated 15 immunogenic antigens using autologous sera. Among the antigens most frequently identified were the lymphoid blast crisis oncogene (LBC), an unknown hypothetical protein and the p53-binding protein (TP53 BP), which have already been associated with tumor development. Of the immunogenic antigens, 6 map to chromosomes that are frequently altered in squamous cell lung carcinoma. SEREX database analysis showed that 7 of the identified immunogenic antigens have been associated with the humoral immune response in other human tumors. Screening with heterologous sera of patients with lung carcinoma identified 4 antigens, including human protein kinase C and TP53 BP, which have also been found by autologous screening. Only 1 of the 15 identified antigens reacted with any of the 36 control sera, which were taken from individuals without known disease. Sera from adenocarcinoma and large cell carcinoma of the lung were not reactive for the antigens. In summary, using 2 newly established cDNA libraries, we isolated 15 novel antigens, which were subsequently evaluated for the frequency of their corresponding antibodies in autologous, normal and heterologous sera; their chromosomal localization; and their correlation with survival after surgery.

Prognostic factors in non-small cell lung cancer: a decade of progress

STUDY OBJECTIVES

To provide a systematic overview of the literature investigating patient and tumor factors that are predictive of survival for patients with non-small cell lung cancer (NSCLC), and to analyze patterns in the design of these studies in order to highlight problematic aspects of their design and to advocate for appropriate directions of future studies.

DESIGN

A systematic search of the MEDLINE database and a synthesis of the identified literature.

MEASUREMENTS AND RESULTS

The database search (January 1990 to July 2001) was carried out combining the MeSH terms prognosis and carcinoma, nonsmall cell lung. Eight hundred eighty-seven articles met the search criteria. These studies identified 169 prognostic factors relating either to the tumor or the host. One hundred seventy-six studies reported multivariate analyses. Concerning 153 studies reporting a multivariate analysis of prognostic factors in patients with early-stage NSCLC, the median number of patients enrolled per study was 120 (range, 31 to 1,281 patients). The median number of factors reported to be significant in univariate analyses was 4 (range, 2 to 14 factors). The median number of factors reported to be significant in multivariate analyses per study was 2 (range, 0 to 6 factors). The median number of studies examining each prognostic factor was 1 (range, 1 to 105 studies). Only 6% of studies addressed clinical outcomes other than patient survival.

CONCLUSIONS

While the breadth of prognostic factors studied in the literature is extensive, the scope of factors evaluated in individual studies is inappropriately narrow. Individual studies are typically statistically underpowered and are remarkably heterogeneous with regard to their conclusions. Larger studies with clinically relevant modeling are required to address the usefulness of newly available prognostic factors in defining the management of patients with NSCLC.

Prediction of pelvic lymph node metastasis by the ratio of cathepsin B to stefin A in patients with prostate carcinoma

BACKGROUND

Pathologic grade and/or histologic score, extraprostatic extension indicated by invasion of the prostatic capsule, margin, and/or seminal vesicles by prostate cancer cells, serum total prostate-specific antigen (PSA), free PSA, complexed PSA levels and/or their ratios, regional pelvic lymph node metastases, and clinical staging have been used to diagnose and monitor the treatment of prostate carcinoma (PC) patients. The Gleason grading system is also used to grade/score a patient's stage of disease, with lower to higher scores indicating progression of PC. However, Gleason's system cannot be used to distinguish biologically aggressive PCs within a single Gleason score. Our objective was to identify subpopulations (or clones) of aggressive prostate cancers within an individual Gleason score by utilizing biological molecule(s) that also facilitate cancer cell invasion to prostatic stroma and metastasis to the lymph nodes.

MATERIALS AND METHODS

Specimens were collected from 97 patients with PC and from 8 patients with benign prostatic hyperplasia. These patients had not been treated with hormonal and/or chemotherapeutic agents before undergoing a prostatectomy at the Minneapolis Veterans Affairs Medical Center. Formalin-fixed, paraffin or paraplast-embedded prostate tissue sections were stained with hematoxylin and eosin for pathologic diagnosis and adjacent sections were stained for for immunohistochemical study. We also collected data on age, race, extraprostatic extension, margin status, seminal vesicle, and lymph node invasion by cancer cells, clinical stage at prostatectomy, and mortality/survival data, including the available presurgery and postsurgery serum total PSA and prostatic acid phosphatase concentrations in patients. Immunohistochemical localization of mouse or rabbit anti-cathepsin B (CB) antibody IgG and mouse antihuman stefin (cystatin) A IgG was quantified using a computer-based image analysis system equipped with Metamorph software.

RESULTS

CB and stefin A identified aggressive and less aggressive clones of PCs within an individual Gleason score. Tumors with a Gleason Score of 6 that are similar histologically and morphologically were heterogeneous with respect to the ratios of CB to stefin A (CB > stefin A, CB = stefin A, and CB < stefin A). We also found a significant positive association (P = 0.0066) between ratios of CB and stefin A (CB > stefin A) and the incidence of pelvic lymph node metastases, but not with ratios of CB less than stefin A and/or ratios of CB equal to stefin A. Patients with Gleason 7 PCs had a higher incidence of positive lymph nodes than those with Gleason Score 6 tumors. Our data indicated that mortality rates increased in patients when the ratios of CB were greater than stefin A.

CONCLUSIONS

PC within an individual Gleason score is a heterogeneous tumor that contains clones or subpopulations of aggressive and less aggressive tumors that can be defined by the ratios of CB to stefin A. PC with an aggressive clone can be identified when the ratio of CB is greater than that of stefin A. Less aggressive clones are identified when the ratio of CB is less than that of stefin A or when the ratio of CB is equal to that of stefin A. The ratios of CB to stefin A can be used in the differential diagnosis and treatment of patients with PC. This is the first report to identify phenotypes of aggressive and less aggressive PCs within a Gleason score.

Near-infrared fluorescent nanoparticles as combined MR/optical imaging probes

A number of quantitative three-dimensional tomographic near-infrared fluorescence imaging techniques have recently been developed and combined with MR imaging to yield highly detailed anatomic and molecular information in living organisms (1, 2). Here we describe magnetic nanoparticle based MR contrast agents that have a near-infrared fluorescence (NIRF) that is activated by certain enzymes. The probes are prepared by conjugation of arginyl peptides to cross-linked iron oxide amine (amino-CLIO), either by a disulfide linkage or a thioether linker, followed by the attachment of the indocyanine dye Cy5.5. The NIRF of disulfide-linked conjugate was activated by DTT, while the NIRF of thioether-linked conjugate was activated by trypsin. Fluorescent quenching of the attached fluorochrome occurs in part due to the interaction with iron oxide, as evident by the activation of fluorescence with DTT when nanoparticles that have less than one dye attached per particle. With a SC injection of the probe, axillary and brachial lymph nodes were darkened on MR images and easily delineated by NIRF imaging. The probes may provide the basis for a new class of so-called smart nanoparticles, capable of pinpointing their position through their magnetic properties, while providing information on their environment by optical imaging techniques.

Ratio Imaging of Enzyme Activity Using Dual Wavelength Optical Reporters

The design of near-infrared fluorescent (NIRF) probes that are activated by specific proteases has, for the first time, allowed enzyme activity to be imaged in vivo. In the current study, we report on a method of imaging enzyme activity using two fluorescent probes that, together, provide improved quantitation of enzymatic activity. The method employs two chemically similar probes that differ in their degradability by cathepsin B. One probe consists of the NIRF dye Cy5.5 attached to a particulate carrier, a crosslinked iron oxide nanoparticle (CLIO), through cathepsin B cleavable l-arginyl peptides. A second probe consists of Cy3.5 attached to a CLIO through proteolytically resistant d-arginyl peptides. Using mixtures of the two probes, we have shown that the ratio of Cy5.5 to Cy3.5 fluorescence can be used to determine levels of cathepsin B in the environment of nanoparticles with macrophages in suspension. After intravenous injection, tissue fluorescence from the nondegradable Cy3.5–d-arginyl probe reflected nanoparticle accumulation, while fluorescence of the Cy5.5–l-arginyl probe was dependent on both accumulation and activation by cathepsin B. Dual wavelength ratio imaging can be used for the quantitative imaging of a variety of enzymes in clinically important settings, while the magnetic properties of the probes allow their detection by MR imaging.

Plasma membrane association of cathepsin B in human prostate cancer: biochemical and immunogold electron microscopic analysis

BACKGROUND

Cathepsin B (CB), a cysteine protease, is usually found in perinuclear lysosomes of epithelial cells of normal organs and non-malignant tumors, but is associated with the plasma membranes of many solid organ malignant tumors. Plasma membrane localized CB facilitates degradation of extracellular matrix proteins and progression of tumor cells from one biological compartment to another. The activities of CB and its subcellular distribution have not been investigated in malignant prostate. Our objective was to examine the subcellular distribution of CB by determining the activities of CB in lysosome and plasma membrane/endosome subcellular fractions and its subcellular localization by immunogold electron microscopy.

METHODS

Prostate tissue pieces obtained immediately after prostatectomy were homogenized and fractionated into subcellular components for determining biochemical activities of CB and cysteine protease inhibitors (CPIs). Distribution of CB was compared with that of prostate specific antigen (PSA, a serine protease), which is abundant in secretory vesicles and granules of normal prostate, benign prostatic hyperplasia (BPH) and malignant prostate cells. Localization of CB was investigated in resin embedded lysosomes and plasma membrane/endosome subcellular fractions and in prostate tissue sections by immunogold electron microscopy.

RESULTS

We have demonstrated the specificity of CB activity in human prostate homogenates by using a variety of inhibitors in our assay. We did not find any difference in the specific activity of CB based on protein or DNA content in homogenates of malignant prostate (Gleason histologic scores 5-7) and BPH (no histological evidence of cancer) whether it was measured by chromogenic or fluorogenic peptide substrate assay techniques. We found significantly higher activities of CB in the plasma membrane/endosome fractions of malignant prostate than in BPH. In contrast, CPI activity was increased relative to CB activity in plasma membrane/endosome fraction of BPH versus prostate cancer. Our data indicated a shift in the balance of enzyme to inhibitor that would favor increased activities of CB in prostate cancer. The immunogold microscopic study showed specific localization of CB in plasma membrane. They also showed localization of CB in lysosomes that were often adjacent to luminal and/or basal surfaces of malignant cells in contrast to the usual perinuclear distribution of lysosomes in hyperplastic prostate glands. PSA was localized in secretory granules and vesicles, including the plasma membranes and secretory blebs in malignant prostate cells. Occasional PSA positive secretory vesicles or membrane profiles were seen in the plasma membrane/endosomal and lysosomal fractions.

CONCLUSIONS

The increased activity of CB in plasma membrane/endosomal fractions is associated with malignant prostate and not with BPH or normal prostate. Morphologic distribution CB is associated with the plasma membranes or lysosomes adjacent to apical and basal cell surfaces. This distribution is characteristic feature prostate cancer cells, but not in BPH or normal prostate cells. Subcellular distribution of PSA occurs in secretory vesicles and granules of the cytoplasm, but not in lysosomes. Our biochemical and morphological data could be used to distinguish malignant prostates from non-malignant tumors.

Ratio of cathepsin B to stefin A identifies heterogeneity within Gleason histologic scores for human prostate cancer

BACKGROUND

Cathepsin B (CB), a lysosomal cysteine protease, is involved in degradation of extracellular matrix proteins and progression of tumor cells from one biological compartment to another in many solid organ cancers, including prostate cancer. Our objective was to identify patterns of distribution of CB and its endogenous cellular inhibitor stefin A in cryostat sections of frozen BPH and prostate cancer tissue samples and to define these patterns in relation to Gleason histologic scores, clinical stages, and serum total PSA levels.

METHODS

We localized CB and stefin A in the same sections using polyclonal and monoclonal antibody immunoglobulin G (IgGs) against CB and stefin A using immunofluorescence and confocal microscopic techniques. Only cryostat sections of frozen prostates were used in localizations of CB and stefin A.

RESULTS

Benign prostatic hyperplasia (BPH) showed similar localization patterns for CB and stefin A and a ratio of 1 was indicated by CB = stefin A. Confocal studies indicated that most CB and stefin A sites in BPH glandular cells overlapped as shown by the yellow fluorescence of their co-localization. We found considerable variability in individual localization of CB and stefin A within and between Gleason histologic scores for prostate cancers. This variability was also found in Gleason score 6 tumors that are otherwise considered similar histologically and morphologically. Negative control sections did not show localization of CB by FITC, stefin A by Cy3 or yellow fluorescence for co-localization. Our analysis of the ratio of CB to stefin A showed three patterns, namely CB = stefin A, CB > stefin A, and CB < stefin A, within each Gleason score evaluated by us. Confocal microscopy showed more sites of yellow fluorescence when the ratio was CB = stefin A than those found in CB > stefin A or CB < stefin A. Statistical analyses showed prostate cancer cases with ratios of CB > stefin A (P < 0.05) and CB < stefin A (P < 0.05) significantly different from normal prostate and BPH which had ratios of CB = stefin A. Regression analysis did not show any specific relationship between the ratio of CB to stefin A and Gleason scores, clinical stages, and serum total prostate specific antigen (PSA) levels in prostate cancers. Analysis of our data indicates that the homeostatic balance between the enzyme and inhibitor was altered even in Gleason histologic score 6 tumors that are usually considered histologically similar by glandular differentiation.

CONCLUSIONS

We have shown that prostate cancer is a heterogeneous tumor within each Gleason histological score regardless of the progression indicated by lower to higher Gleason score tumors. The ratio of CB > stefin A would indicate a preponderance of enzyme that would favor degradation of extracellular matrix proteins and progression of tumor cells in biological compartments. These tumors are expected to be aggressive prostate cancers. In contrast, prostate tumors showing ratios of CB < stefin A and CB = stefin A are expected to be less aggressive prostate cancers. This is the first report to define heterogeneity within any Gleason score for prostate cancers by the ratios of CB to stefin A.

Down-regulation of cathepsin B expression impairs the invasive and tumorigenic potential of human glioblastoma cells

Increases in abundance of cathepsin B transcript and protein correlate with increases in tumor grade and alterations in subcellular localization and activity of cathepsin B. The enzyme is able to degrade the components of the extracellular matrix (ECM) and activate other proteases capable of degrading ECM. To investigate the role played by this protease in the invasion of brain tumor cells, we transfected SNB19 human glioblastoma cells with a plasmid containing cathepsin B cDNA in antisense orientation. Control cells were transfected with vector alone. Clones expressing antisense cathepsin B cDNA exhibited significant reductions in cathepsin B mRNA, enzyme activity and protein compared to controls. Matrigel Invasion assay showed that the antisense-transfected cells had a markedly diminished invasiveness compared with controls. When tumor spheroids containing antisense transfected SNB19 cells expressing reduced cathepsin B were co-cultured with fetal rat brain aggregates, invasion of fetal rat brain aggregates was significantly reduced. Green Fluorescent Protein (GFP) expressing parental cells and antisense transfectants were generated for detection in mouse brain tissue without any post-chemical treatment. Intracerebral injection of SNB19 stable antisense transfectants resulted in reduced tumor formation in nude mice. These results strongly support a role for cathepsin B in the invasiveness of human glioblastoma cells and suggest cathepsin B antisense may prove useful in cancer therapy.

Cysteine proteinase cathepsin H in tumours and sera of lung cancer patients: relation to prognosis and cigarette smoking

In order to evaluate the role of cysteine peptidase cathepsin H (Cath H) in human lung cancer its protein levels were determined in 148 pairs of lung tumour tissue and adjacent non-tumourous lung parenchyma using the enzyme-linked immunosorbent assay technique. Additionally, Cath H levels were determined in sera of 171 patients with malignant tumours, 34 patients with benign lung diseases and 47 healthy controls. The median level of Cath H in tumour tissue was 0.64 times that in the corresponding lung parenchyma. Relating tumour levels with histological type we found higher Cath H levels in small-cell and adenocarcinomas and lower levels in squamous cell carcinoma, large-cell carcinoma and secondary tumours. A significant difference in Cath H level between lung tumour tissue and non-tumourous lung parenchyma was associated with the group of cigarette smokers (156 vs 263 ng mg(-1) protein, P < 0.001). For this group of patients Cath H tumour levels correlated with the survival rate, while for the entire patient population this was not the case. Smokers with high tumour levels of Cath H experienced poor survival. Cath H was significantly higher in sera of patients with malignant and benign lung diseases than in control sera (P < 0.001). The increase was significant for all histological types, being the highest in small-cell and squamous cell carcinomas. Our study reveals that in lung tumours there is different behaviour of Cath H compared with other cysteine peptidases, e.g. cathepsin B and cathepsin L. Variations between tissue and serum levels of Cath H indicate either reduced expression or enhanced secretion of this enzyme in lung tumours.