ARTICLE |
Correspondence to: Cornelis J. F. Van Noorden, Dept. of Cell Biology and Histology, Academic Medical Center, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands. E-mail: c.j.vannoorden@amc.uva.nl
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Summary |
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Cathepsin B is a lysosomal cysteine proteinase that may participate in cancer progression. We compared localization of its protein and activity during progression of human colorectal cancer. In adenomas and carcinomas, protein expression and, particularly, activity were elevated compared with those in normal colorectal mucosa. In normal mucosa, cathepsin B protein expression was moderate in stroma and variable in epithelium, whereas activity was mainly present in distinct areas of stroma directly underneath the surface of the colon and in epithelium at the surface of the colon. Stroma in adenomas and carcinomas contained moderate to high protein levels but little activity except for areas of angiogenesis, inflammation, and necrosis, in which activity was high. In adenomas and the majority of well-differentiated carcinomas and moderately differentiated carcinomas, cathepsin B protein and activity were found in granular form in the epithelium, close to the basement membrane. Protein and activity levels were low and diffusely distributed in cancer cells in the remainder of the well-differentiated and moderately differentiated carcinomas and in all poorly differentiated carcinomas. Invasive fronts in most cancers contained moderate protein levels but high activity. We conclude that (a) activity localization is essential to understand the role of cathepsin B in cancer progression, and (b) cathepsin B activity in human colon is associated with invasion of cancer cells, endothelial cells, and inflammatory cells, and in cell death, both apoptotic and necrotic.
(J Histochem Cytochem 48:14211430, 2000)
Key Words: colorectal cancer, invasion, metastasis, cysteine proteinase, cathepsin B, immunohistochemistry, enzyme histochemistry, image analysis
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Introduction |
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IN THE WESTERN WORLD, colon carcinoma is a major cause of death, mainly due to local invasion of the cancer cells and their distant metastasis. Defining the exact role of proteinases in progression of colon cancer can be important for better understanding of processes involved in invasion and metastasis, development of prognostic markers, and design of selective inhibitors of the proteases intended for therapy (
Proteinases can facilitate invasion and metastasis in a number of ways, including detachment of individual cells from the primary tumor, penetration of surrounding tissues and the vascular system by degradation of basement membranes and extracellular matrix (ECM), adhesion, and detachment by shedding adhesion molecules (
Cathepsin B is the major representative of the cysteine proteinases and is present in lysosomes of all types of cells under normal conditions (
The role of cathepsin B in progression of colorectal cancer has been studied but the results are contradictory. This is particularly caused by the application of different techniques. For example,
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Materials and Methods |
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Tissue Specimens
Forty samples of human colorectal carcinomas with adjacent normal mucosa were obtained from the Pathology Department at Kbenhavns Kommunes Hvidovre Hospital (University of Copenhagen; Hvidovre, Denmark). Four biopsies of well-differentiated carcinomas (10%), 25 biopsies of moderately differentiated carcinomas (62%), and 11 poorly differentiated carcinomas (28%) were collected. Four samples of tubular adenomatous polyps and three samples of normal mucosa taken at least 5 cm from the sites of the carcinomas were obtained from the Pathology Department (University of Maastricht; The Netherlands). Moreover, normal mucosa adjacent to tumors was analyzed. After resection, the tissue samples were immediately frozen in liquid nitrogen and stored at -80C until used.
Preparation of Cryostat Sections
Serial cryostat sections (6 µm thick) were cut at a cabinet temp of -25C on a motor-driven cryostat (Bright; Huntingdon, UK) at a low but constant speed to minimize variation in section thickness. The sections were picked up on clean glass slides and stored at -80C until used.
Histopathology
Pathological examination was performed with the use of hematoxylineosin (H&E)-stained sections of each specimen. For orientation in the sections and to facilitate analysis of serial sections, high-resolution composite images of entire H&E-stained sections of all biopsies were taken. Digital images were captured using a light microscope (BH2; Olympus, Tokyo, Japan) with a x2 SPlan FL 2 objective and a CCD black-and-white video camera (Sony; ATV Horn, Aalen, Germany). The camera was coupled via a frame grabber (maximal size 786 x 512) to an image analysis system with the KS 300 software package (Kontron; Eching, Germany). Camera signal and set up were adjusted according to the recommendations of
Immunohistochemistry
A rabbit polyclonal antibody against both the pro-form and the active form of human cathepsin B (Calbiochem; Cambridge, UK), which recognizes an epitope of the heavy chain of cathepsin B, was applied to localize cathepsin B with the use of the immunogoldsilver labeling technique. Sections were air-dried. Blocking of endogenous peroxidase activity was performed in methanol containing 0.45% hydrogen peroxide for 15 min. Sections were rinsed three times for 5 min in 50 mM Tris rinsing buffer containing 0.05% Tween-20 (Merck; Darmstadt, Germany). To reduce nonspecific binding, sections were rinsed in Tris buffer containing 3% fat-free milk powder, 0.1% fish gelatin, and 0.05% saponin (incubation buffer). The antibody was used at a concentration of 1 µg/ml. After rinsing in Tris buffer containing 0.05% (v/v) Tween-20, sections were incubated with the secondary anti-rabbit IgG conjugated with 0.8 nm colloidal gold (Aurion; Wageningen, The Netherlands) at a dilution of 1:30 in incubation buffer for 60 min at 20C. After rinsing in Tris buffer, additional stabilization of the immunogold complex was performed by a fixation step in 2% glutaraldehyde in Tris buffer for 15 min, followed by three rinses in bidistilled water for 5 min each. Sections were stained in the dark for 9 min in silver developer, freshly prepared according to
Images of the immunohistochemically stained sections were taken with an Axioskop light microscope (Zeiss; Oberkochen, Germany) using epipolarized light for the visualization of the immunogoldsilver reaction product and a x40 waterimmersion objective.
Enzyme Histochemistry
The incubation medium to demonstrate cathepsin B activity consisted of 100 mM phosphate buffer (pH 6.0), 1.3 mM EDTA (disodium salt), 1 mM dithiothreitol, 2.67 mM L-cysteine, 1 mM 2-hydroxy-5-nitrobenzaldehyde (Merck) as coupling agent and 1 mM N-CBZ-Ala-Arg-Arg-4-methoxy-2-naphthylamide (Enzyme Systems Products; Livermore, CA) as substrate for cathepsin B (
The image analysis system has been described in detail by
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Results |
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Localization of Cathepsin B Activity
Cathepsin B activity was present in all specimens (Fig 1a). Activity was optimally localized after 15 min of incubation. Incubations in the presence of FMK did not produce any yellow fluorescence, indicating the specificity of production of fluorescence by cathepsin B activity (Fig 1b).
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Immunolocalization of Cathepsin B
The polyclonal antibody demonstrated cathepsin B in epithelium and stroma of colorectal mucosa (Fig 1d). Control reactions with an irrelevant rabbit antibody raised against salmon vitellogenin at the same dilution resulted in low levels of positivity (Fig 1f). Sometimes, precipitate in the lumen of the colon and rectum reacted nonspecifically (Fig 1d and Fig 2d). Positivity in the lumen was ignored in all further studies.
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Cathepsin B in Colorectal Cancer
Table 1 summarizes the semiquantitative analysis of localization patterns of cathepsin B protein and activity in relation to colorectal cancer.
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Cathepsin B in Normal Colorectal Mucosa
Cathepsin B protein was present in variable amounts in epithelium of the crypts. In most cases, epithelium contained moderate amounts of cathepsin B protein (Fig 2f), but sometimes epithelium in crypts was almost devoid of cathepsin B (Fig 2d). Stroma also contained moderate amounts of cathepsin B that was homogeneously distributed (Fig 2d and Fig 2f).
Normal colorectal epithelium showed cathepsin B activity that was heterogeneously localized. Activity was mainly observed in epithelium at the colorectal surface, whereas epithelium in the crypts showed hardly any activity (Fig 2b and Fig 2c). Stroma was usually negative except for distinct areas that were mainly found directly underneath the colorectal surface (Fig 2b and Fig 2c).
When the localization patterns of cathepsin B protein and activity are compared, it can be concluded that (older) epithelium at the colorectal surface expressed both cathepsin B protein and activity. When epithelium in the crypts contained cathepsin B protein, it was not active. Stroma contained moderate amounts of cathepsin B protein that was homogeneously distributed, but it was active only in certain areas that were mainly found directly underneath the colorectal surface (cf. Fig 2c and Fig 2d). These localization patterns of cathepsin B protein and activity were similar in all normal mucosa investigated, whether or not it was adjacent to tumors.
Cathepsin B in Adenomas
Cathepsin B protein was mainly localized in tubule adenomas at the basal side of epithelium adjacent to the basement membrane (Fig 3b). This pattern was distinctly different from that in normal epithelium (cf. Fig 2d and Fig 2f). The entire epithelium of all adenomas contained cathepsin B protein. Cathepsin B protein expression in stroma was similar to that in normal colorectal tissue. Activity was elevated in epithelium of all adenomas compared with normal epithelium (cf. Fig 2c and Fig 3a). It was localized along its basal side. Stroma contained only little activity (Fig 3a).
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When protein and activity distribution patterns were compared, we conclude that a large fraction of cathepsin B was localized in granules at the basal side of epithelium and that this fraction was active (Fig 3a and Fig 3b). Cathepsin B in stroma did not show distinct alterations in adenomas compared with normal colorectal tissue.
Cathepsin B in Well-differentiated Carcinomas
Epithelium in well-differentiated tumors showed an expression pattern of cathepsin B protein and activity that was largely similar to that in adenomas, whereas stroma contained higher amounts of cathepsin B protein than in adenomas (Fig 3c and Fig 3d). Furthermore, a transition was observed in this stage in specific sites of four tumors towards a localization of both protein and activity over the entire cytoplasm of cancer cells (Fig 3c and Fig 3d), as was observed in half of moderately and in all poorly differentiated carcinomas (see below).
Comparison of the localization patterns of cathepsin B protein and activity showed that these were in agreement with each other, except that stroma contained large amounts of inactive cathepsin B.
Cathepsin B in Moderately Differentiated Carcinomas
Expression patterns of cathepsin B protein and activity in moderately differentiated carcinomas were similar to those in well-differentiated carcinomas (Fig 3e). Epithelial cells in 50% of the tumors contained cathepsin B protein (not shown) and activity at the basal side of cells (Fig 3e), and in 50% it was diffusely distributed throughout their cytoplasm with a tendency towards localization in apical regions of the cells (Fig 3f). Stroma was strongly positive for protein (not shown), but in most cases not for activity (Fig 3e). However, in specific sites of some tumors, stroma was strongly positive for both protein (not shown) and activity (Fig 3f), similarly to poorly differentiated carcinomas (see below).
Cathepsin B in Poorly Differentiated Carcinomas
Epithelium in poorly differentiated carcinomas contained low levels of cathepsin B protein that was diffusely distributed in cancer cells, whereas stroma contained high cathepsin B levels (Fig 3h). Activity was significantly decreased in cancer cells in poorly differentiated carcinomas compared with that in moderately and well-differentiated colorectal carcinomas (Fig 3g), except for satellite-like protrusions of cancer cells that showed high activity (Fig 4). When cathepsin B activity was present, it was diffusely distributed over the cytoplasm of the cancer cells.
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Cathepsin B and Invasive Fronts, Angiogenesis, Necrosis, and Inflammation
Invasive fronts and satellites of cancer cells showed moderate protein levels of cathepsin B, but its activity was high (Fig 1 and Fig 4).
When activity was present in stroma, it was in defined tissue compartments where angiogenesis (Fig 5a and Fig 5b), necrosis (Fig 5c and Fig 5d), or inflammatory cells (Fig 5e and Fig 5f) were present. Lymph follicles were frequently observed, which did not show any activity.
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Discussion |
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Localization of cathepsin B protein and activity in serial sections revealed a distinct pattern in relation to colorectal carcinogenesis. In normal colorectal mucosa, cathepsin B protein was present in the larger part of the epithelium but was active only in the older cells at the colorectal surface (
Stroma also showed distinct changes in cathepsin B expression during tumor progression. It contained higher amounts of cathepsin B protein in malignant tumors than in adenomas and normal colonic mucosa. In general, stromal cathepsin B protein expression was highest in poorly differentiated carcinomas. Whereas cathepsin B protein is present rather homogeneously in stroma, cathepsin B activity is localized in distinct patterns throughout tumor progression from normal mucosa to poorly differentiated carcinomas. Activity in stroma was particularly linked with angiogenesis, necrosis, and inflammation.
Our study links previous seemingly contradictory studies of cathepsin B in colorectal cancer. We found the inverse relationship between differentiation grade and cathepsin B activity that Murnane and co-workers (
The high cathepsin B activity in invasive fronts of the tumors correlates well with the link between cathepsin B protein expression and shortened survival as was found by Sloane and co-workers (
In conclusion, our study combining localization of protein and activity of cathepsin B indicates that cathepsin B expression in colorectal cancer shows a distinct pattern. Its activity is markedly linked to processes such as apoptosis in normal epithelium and necrosis in tumors, and to invasion of cancer cells, angiogenesis, and inflammation. In particular, the link with invasion and angiogenesis and the fact that cathepsin B can be expressed extracellularly in these processes make the enzyme an attractive target for therapeutic strategies using selective inhibitors of the extracellular form of cathepsin B. In this way, the enzyme in the lysosomes is kept intact for its normal function in protein degradation. This approach was effective in a rat model of colon cancer metastasis in the liver, in which oral treatment of the rats with a water-soluble selective inhibitor of cathepsin B reduced metastasis (
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Footnotes |
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1 These authors contributed equally to this work.
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Acknowledgments |
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We are grateful to Mr Jan Peeterse for preparation of the digital images and to Ms Trees M.S. Pierik for preparation of the manuscript.
Received for publication December 7, 1999; accepted May 3, 2000.
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Literature Cited |
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![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Afonso S, Romagnano L, Babiarz B (1999) Expression of cathepsin proteinases by mouse trophoblast in vivo and in vitro. Dev Dyn 216:374-384[Medline]
Basbaum CB, Werb Z (1996) Focalized proteolysis: spatial and temporal regulation of extracellular matrix degradation at the cell surface. Curr Opin Cell Biol 8:731-738[Medline]
Bleeker FE, Hazen LGM, Köhler A, Van Noorden CJF (2000) Direct comparison of the sensitivity of enzyme histochemical and immunohistochemical methods: cathepsin B expression in human colorectal mucosa. Acta Histochem 102:247-257[Medline]
Brünner N, Matrisian LM, Danø K, eds. (1999) Proteases and Protease Inhibitors in Cancer. Copenhagen, Munksgaard
Buck MR, Karustis DG, Day NA, Honn KV, Sloane BF (1992) Degradation of extracellular-matrix proteins by human cathepsin B from normal and tumour tissues. Biochem J 282:273-278[Medline]
Campo E, Munoz J, Miquel R, Palacin A, Cardesa A, Sloane BF, EmmertBuck MR (1994) Cathepsin B expression in colorectal carcinomas correlates with tumor progression and shortened patient survival. Am J Pathol 145:301-309[Abstract]
Chieco P, Jonker A, Melchiorri C, Vanni G, Van Noorden CJF (1994) A user's guide for avoiding errors in absorbance image cytometry: a review with original experimental observation. Histochem J 26:1-19[Medline]
Coulibaly S, Schwihla H, Abrahamson M, Albini A, Cerni C, Clark JL, Ng KM, Katunuma N, Schlappack O, Glossl J, Mach L (1999) Modulation of invasive properties of murine squamous carcinoma cells by heterologous expression of cathepsin B and cystatin C. Int J Cancer 83:526-531[Medline]
Danscher G, Nörgaard JOR (1983) Light microscopic visualization of colloidal gold on neoplastic fate in a teleost fish model. Toxicol Pathol 19:237-250
Del Re EC, Shuja S, Cai J, Murnane MJ (2000) Alterations in cathepsin H activity and protein patterns in human colorectal carcinomas. Br J Cancer 82:1317-1326[Medline]
Demchik LL, Sameni M, Nelson K, Mikkelsen T, Sloane BF (1999) Cathepsin B and glioma invasion. Int J Dev Neurosci 17:483-494[Medline]
EmmertBuck MR, Roth MJ, Zhuang Z, Campo E, Rozhin J, Sloane BF, Liotta LA, StetlerStevenson WG (1994) Increased gelatinase A (MMP-2) and cathepsin B activity in invasive tumor regions of human colon cancer samples. Am J Pathol 145:1285-1290[Abstract]
Erdel M, Trefz G, Spiess E, Habermaas S, Spring H, Lah T, Ebert W (1990) Localization of cathepsin B in two human lung cancer cell lines. J Histochem Cytochem 38:1313-1321[Abstract]
Esser RE, Angelo RA, Murphey MD, Watts LM, Thornburg LP, Palmer JT, Talhouk JW, Smith RE (1994) Cysteine proteinase inhibitors decrease articular cartilage and bone destruction in chronic inflammatory arthritis. Arthritis Rheum 37:236-247[Medline]
Everts V, Beertsen W, TigchelaarGutter W (1985) The digestion of phagocytosed collagen is inhibited by the proteinase inhibitors leupeptin and E-64. Collagen Relat Res 5:315-336
Foekens JA, Kos J, Peters HA, Krasovec M, Look MP, Cimerman N, MeijerVan Gelder ME, HenzenLogmans SC, Van Putten WLJ, Klijn JGM (1998) Prognostic significance of cathepsins B and L in primary human breast cancer. J Clin Oncol 16:1013-1021[Abstract]
Frosch BA, Berquin I, EmmertBuck MR, Moin K, Sloane BF (1999) Molecular regulation membrane association and secretion of tumor cathepsin B. APMIS 107:28-37[Medline]
Guenette RS, Mooibroek M, Wong K, Wong P, Tenniswood M (1994) Cathepsin B, a cysteine protease implicated in metastatic progression, is also expressed during regression of the rat prostate and mammary glands. Eur J Biochem 226:311-321[Abstract]
Herszenyi L, Plebani M, Carraro P, De Paoli M, Roveroni G, Cardin R, Tulassay Z, Naccarato R, Farinati F (1999) The role of cysteine and serine proteases in colorectal carcinoma. Cancer 86:1135-1142[Medline]
Hirai K, Yokoyama M, Asano G, Tanaka S (1999) Expression of cathepsin B and cystatin C in human colorectal cancer. Hum Pathol 30:680-686[Medline]
Hooper NM, Karran EH, Turner AJ (1997) Membrane protein secretases. Biochem J 321:265-279[Medline]
IacobuzioDonahue CA, Shuja S, Cai J, Peng P, Murnane MJ (1997) Elevations in cathepsin B protein content and enzyme activity occur independently of glycosylation during colorectal tumor progression. J Biol Chem 272:29190-29199
Johnsen M, Lund LR, Rmer J, Almholt K, Dan
K (1998) Cancer invasion and tissue remodeling: common themes in proteolytic matrix degradation. Curr Opin Cell Biol 10:667-671[Medline]
Jonker A, Geerts WJ, Chieco P, Moorman AFM, Lamers WH, Van Noorden CJF (1997) Basic strategies for valid cytometry using image analysis. Histochem J 29:347-364[Medline]
Keppler D, Fondaneche MC, DaletFumeron V, Pagano M, Burtin P (1988) Immunohistochemical and biochemical study of a cathepsin B-like proteinase in human colonic cancers. Cancer Res 48:6855-6862[Abstract]
Keppler D, Sameni M, Moin K, Mikkelsen T, Diglio CA, Sloane BF (1996) Tumor progression and angiogenesis: cathepsin B & Co. Biochem Cell Biol 74:799-810[Medline]
Keppler D, Sloane BF (1996) Cathepsin B: multiple enzyme forms from a single gene and their relation to cancer. Enzyme Protein 49:94-105[Medline]
Kirschke H, Barrett AJ, Rawlings ND (1995) Cathepsin B (EC 3.4.22.1). Protein Profile 2:15881591
Kobayashi H, Ohi H, Sugimura M, Shinohara H, Fujii T, Terao T (1992) Inhibition of in vitro ovarian cancer cell invasion by modulation of urokinase-type plasminogen activator and cathepsin B. Cancer Res 52:3610-3614[Abstract]
Kobayashi H, Schmitt M, Goretzki L, Chucholowski N, Calvete J, Kramer M, Gunzler WA, Janicke F, Graeff H (1991) Cathepsin B efficiently activates the soluble and the tumor cell receptor-bound form of the proenzyme urokinase-type plasminogen activator (Pro-uPA). J Biol Chem 266:5147-5152
Koblinski JE, Ahram M, Sloane BF (2000) Unraveling the role of proteases in cancer. Clin Chim Acta 291:113-135[Medline]
Kohn EC, Liotta LA (1995) Molecular insights into cancer invasion: strategies for prevention and intervention. Cancer Res 55:1856-1862[Abstract]
Kostoulas G, Lang A, Nagase H, Baici A (2000) Stimulation of angiogenesis through cathepsin B inactivation of the tissue inhibitors of matrix metalloproteinases. FEBS Lett 466:394
Lah TT, Kalman E, Najjar D, Gorodetsky E, Brennan P, Somers R, Daskal I (2000) Cells producing cathepsins D, B, and L in human breast carcinoma and their association with prognosis. Hum Pathol 31:149-160[Medline]
Liotta LA, Steeg PS, Stetler-Stevenson WG (1991) Cancer metastasis and angiogenesis: an imbalance of positive and negative regulation. Cell 64:327-336[Medline]
Maciewicz RA, Wardale JR, Etherington DJ, Paraskeva C (1989) Immunodetection of cathepsins B and L present in and secreted from human premalignant and malignant colorectal tumour cell lines. Int J Cancer 43:478-486[Medline]
Maciewicz RA, Wotton SF, Etherington DJ, Duance VC (1990) Susceptibility of the cartilage collagens types II, IX and XI to degradation by the cysteine proteinases, cathepsins B and L. FEBS Lett 269:189-193[Medline]
Mignatti P, Rifkin DB (1995) Biology and biochemistry of proteinases in tumor invasion. Physiol Rev 73:161-195
Mort JS, Recklies AD (1986) Interrelationship of active and latent secreted human cathepsin B precursors. Biochem J 233:57-63[Medline]
Murnane MJ, Sheahan K, Ozdemirli M, Shuja S (1991) Stage-specific increases in cathepsin B messenger RNA content in human colorectal carcinoma. Cancer Res 51:1137-1142[Abstract]
Navab R, Mort JS, Brodt P (1997) Inhibition of carcinoma cell invasion and liver metastases formation by the cysteine proteinase inhibitor E-64. Clin Exp Metast 15:121-129[Medline]
Nishimura Y, Kawabata T, Kato K, Kobayashi H, Schmitt M, Goretzki L, Chucholowski N, Calvete J, Kramer M, Gunzler WA, Janicke F, Graeff H (1988) Identification of latent procathepsins B and L in microsomal lumen: characterization of enzymatic activation and proteolytic processing in vitro. Arch Biochem Biophys 261:64-71[Medline]
Qian F, Chan SJ, Ackkar C, Steiner DF, Frankfater A (1994) Transcriptional regulation of cathepsin B expression in B16 melanomas of varying metastatic potential. Biochem Biophys Res Commun 202:429-436[Medline]
RamosDeSimone N, HahnDantona E, Sipley J, Nagase H, French DL, Quigley JP (1999) Activation of matrix metalloproteinase-9 (MMP-9) via a converging plasmin/stromelysin-1 cascade enhances tumor cell invasion. J Biol Chem 274:13066-13076
Reddy VY, Zhang QY, Weiss SJ (1995) Pericellular mobilization of the tissue-destructive cysteine proteinases, cathepsins B, L, and S, by human monocyte-derived macrophages. Proc Natl Acad Sci USA 92:3849-3853
Redwood SM, Liu BC, Weiss RE, Hodge DE, Droller MJ (1992) Abrogation of the invasion of human bladder tumor cells by using protease inhibitor(s). Cancer 69:1212-1219[Medline]
Rozhin J, Sameni M, Ziegler G, Sloane BF (1994) Pericellular pH affects distribution and secretion of cathepsin B in malignant cells. Cancer Res 54:6517-6525[Abstract]
Sheahan K, Shuja S, Murnane MJ (1989) Cysteine protease activities and tumor development in human colorectal carcinoma. Cancer Res 49:3809-3814[Abstract]
Shuja S, Sheahan K, Murnane MJ (1991) Cysteine endopeptidase activity levels in normal human tissues, colorectal adenomas and carcinomas. Int J Cancer 49:341-346[Medline]
Sivaparvathi M, Sawaya R, Wang SW, Rayford A, Yamamoto M, Liotta LA, Nicolson GL, Rao JS (1995) Overexpression and localization of cathepsin B during the progression of human gliomas. Clin Exp Metast 13:49-56[Medline]
Sloane BF, Rozhin J, Johnson K, Taylor H, Crissman JD, Honn KV (1986) Cathepsin B: association with plasma membrane in metastatic tumors. Proc Natl Acad Sci USA 83:2483-2487[Abstract]
Spiess E, Brüning A, Gack S, Ulbricht B, Spring H, Trefz G, Ebert W (1994) Cathepsin B activity in human lung tumor cell lines: ultrastructural localization, pH sensitivity, and inhibitor status at the cellular level. J Histochem Cytochem 42:917-929
Strohmaier AR, Porwol T, Acker H, Spiess E (1997) Tomography of cells by confocal laser scanning microscopy and computerassisted three-dimensional image reconstruction: localization of cathepsin B in tumor cells penetrating collagen gels in vitro. J Histochem Cytochem 45:975-983
Tenniswood M (1997) Apoptosis, tumour invasion and prostate cancer. Br J Urol 79(suppl 2):27-34[Medline]
Ulbricht B, Hagmann W, Ebert W, Spiess E (1996) Differential secretion of cathepsins B and L from normal human lung cells stimulated by 12(S)-hydroxy-eicosatetraenoic acid (12(S)-HETE). Exp Cell Res 226:255-263[Medline]
Ulbricht B, Henny H, Horstmann H, Spring H, Faigle W, Spiess E (1997) Influence of 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE) on the localization of cathepsin B and cathepsin L in human lung tumor cells. Eur J Cell Biol 74:294-301[Medline]
Van Noorden CJF, Everts V (1991) Selective inhibition of cysteine proteinases by Z-Phe-AlaCH2F suppresses digestion of collagen by fibroblasts and osteoclasts. Biochem Biophys Res Commun 178:178-184[Medline]
Van Noorden CJF, Frederiks WM (1992) Enzyme Histochemistry. A Laboratory Manual of Current Methods. Oxford, BIOS
Van Noorden CJF, Jonges TGN, MeadeTollin LC, Smith RE, Köhler A (2000) In vivo inhibition of cysteine proteinases delays the onset of growth of human pancreatic cancer explants. Br J Cancer 82:931-936[Medline]
Van Noorden CJF, Jonges GN, Van Marle J, Bissell ER, Griffini P, Jans M, Snel J, Smith RE (1998a) Heterogeneous suppression of experimentally induced colon cancer metastasis in rat liver lobes by inhibition of extracellular cathepsin B. Clin Exp Metast 16:159-167[Medline]
Van Noorden CJF, MeadeTollin LC, Bosman FT (1998b) Metastasis. Am Sci 86:130-141
Van Noorden CJF, Vogels IMC, Everts V, Beertsen W (1987) Localization of cathepsin B activity in fibroblasts and chondrocytes by continuous monitoring of the formation of a final fluorescent reaction product using 5-nitrosalicylaldehyde. Histochem J 19:483-487[Medline]
Webb SD, Sherratt JA, Fish RG (1999) Alterations in proteolytic activity at low pH and its association with invasion: a theoretical model. Clin Exp Metast 17:397-407[Medline]
Werle B, Julke B, Lah T, Spiess E, Ebert W (1997) Cathepsin B fraction active at physiological pH of 7.5 is of prognostic significance in squamous cell carcinoma of human lung. Br J Cancer 75:1137-1143[Medline]