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[Cancer Research 61, 1022-1028, February 1, 2001]
© 2001 American Association for Cancer Research


Experimental Therapeutics

Metastatin: A Hyaluronan-binding Complex from Cartilage That Inhibits Tumor Growth1

Ningfei Liu2, Randall K. Lapcevich2, Charles B. Underhill, Zeqiu Han, Feng Gao, Glenn Swartz, Stacy M. Plum, Lurong Zhang2 and Shawn J. Green2, 3

Department of Oncology, Georgetown University Medical Center, Washington, D.C. 20007 [N. L., C. B. U., Z. H., F. G., L. Z.], and EntreMed, Inc., Rockville, Maryland 20902 [R. K. L., G. S., S. M. P., S. J. G.]


    ABSTRACT
 Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
In this study, a hyaluronan-binding complex, which we termed Metastatin, was isolated from bovine cartilage by affinity chromatography and found to have both antitumorigenic and antiangiogenic properties. Metastatin was able to block the formation of tumor nodules in the lungs of mice inoculated with B16BL6 melanoma or Lewis lung carcinoma cells. Single i.v. administration of Metastatin into chicken embryos inhibited the growth of both B16BL6 mouse melanoma and TSU human prostate cancer cells growing on the chorioallantoic membrane. The in vivo biological effect may be attributed to the antiangiogenic activity because Metastatin is able to inhibit the migration and proliferation of cultured endothelial cells as well as vascular endothelial growth factor-induced angiogenesis on the chorioallantoic membrane. In each case, the effect could be blocked by either heat denaturing the Metastatin or premixing it with hyaluronan, suggesting that its activity critically depends on its ability to bind hyaluronan on the target cells. Collectively, these results suggest that Metastatin is an effective antitumor agent that exhibits antiangiogenic activity.


    INTRODUCTION
 Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
A potential therapeutic target on angiogenic endothelial cells is hyaluronan, a large negatively charged glycosaminoglycan that plays a role in the formation of new blood vessels (1) . Particularly high concentrations of hyaluronan are associated with endothelial cells at the growing tips or sprouts of newly forming capillaries (2 , 3) . Similarly, when cultured endothelial cells are stimulated to proliferate by cytokines, their synthesis of hyaluronan is significantly increased (4) . Interestingly, this stimulation is restricted to endothelial cells derived from the small blood vessels and is not seen in endothelial cells derived from larger ones (4) . In the case of mature blood vessels, hyaluronan is present in perivascular regions and in the junctions between the endothelial cells (5 , 6) . Earlier studies have shown that exogenously applied hyaluronan has different effects on angiogenesis depending on its size, with macromolecular hyaluronan inhibiting vascularization in chicken embryos, and oligosaccharide fragments of hyaluronan stimulating vascularization in the chorioallantoic membrane (7, 8, 9) . Thus, hyaluronan appears to be specifically associated with the endothelial cells of newly forming blood vessels and can influence their behavior.

In addition to hyaluronan, endothelial cells involved in neovascularization also express CD44 and other cell surface receptors for hyaluronan (10, 11, 12) . In particular, endothelial cells associated with tumors express large amounts of CD44 (11) . In previous studies, we have shown that CD44 allows cells to bind hyaluronan so that it can be internalized into endosomal compartments, where the hyaluronan is degraded by the action of acid hydrolases (13 , 14) . Thus, the expression of CD44 by endothelial cells allows them to bind and internalize hyaluronan as well as any associated proteins. The fact that both hyaluronan and CD44 are up-regulated in endothelial cells involved in neovascularization suggests that the turnover of hyaluronan by these cells is much greater than that by cells lining mature blood vessels.

The increased turnover of hyaluronan in tumor-associated endothelial cells suggested a possible mechanism to specifically target these cells. Our initial idea was to use a hyaluronan-binding complex isolated from cartilage to deliver chemotherapeutic agents specifically to these endothelial cells. Purified by affinity chromatography, this hyaluronan-binding complex consists of tryptic fragments of the link protein and aggrecan core protein (5 , 15 , 16) . We intended to couple the hyaluronan-binding complex to a chemotherapeutic agent such as methotrexate and use this derivative to attack endothelial cells. We hoped that this derivative would bind to the hyaluronan on the endothelial cells and then be internalized into lysosomes, where the methotrexate would be released by the action of acid hydrolyses. Surprisingly, however, in the course of these experiments, we found that the hyaluronan-binding complex by itself (i.e., in the absence of a chemotherapeutic agent) inhibited angiogenic activity. Functionally, we termed the hyaluronan-binding complex, which inhibits tumor growth, Metastatin.

In the present study, we demonstrate that Metastatin has a number of intriguing biological activities, including inhibition of endothelial cell proliferation and migration, inhibition of angiogenesis, and suppression of tumor cell growth in chicken embryos and pulmonary metastasis in mice. These effects are blocked by preincubating Metastatin with hyaluronan, suggesting that the activity of Metastatin depends on its ability to bind hyaluronan on the target cells.


    MATERIALS AND METHODS
 Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Preparation of Metastatin.
The hyaluronan-binding complex was prepared by a modified version of the method originally described by Tengblad (15 , 16) . Briefly, bovine nasal cartilage (Pel-Freez, Rogers, AR) was shredded with a Sure-Form blade (Stanley), extracted overnight with 4 M guanidine-HCl and 0.5 M sodium acetate (pH 5.8), and dialyzed against distilled water to which 10x PBS was added to a final concentration of 1x PBS (pH 7.4). The protein concentration was measured, and for each 375 mg of protein, 1 mg of trypsin (type III; Sigma, St. Louis, MO) was added. After digestion for 2 h at 37°C, the reaction was terminated by the addition of 2 mg of soybean trypsin inhibitor (Sigma) for each milligram of trypsin. The digest was dialyzed against 4 M guanidine-HCl and 0.5 M acetate (pH 5.8), mixed with hyaluronan coupled to Sepharose, and then dialyzed against a 10-fold volume of distilled water. The hyaluronan-Sepharose beads were placed into a chromatography column and washed with 1.0 M NaCl, followed by a gradient of 1.0–3.0 M NaCl. Metastatin was eluted from the hyaluronan affinity column with 4 M guanidine-HCl and 0.5 M sodium acetate (pH 5.8), dialyzed against saline, and sterilized by passage through a 0.2-µm-pore filter. For SDS-PAGE analysis, the purified preparation was loaded onto a 10% BisTris nonreducing gel (Novex, Inc.) and subsequently stained with Coomassie Blue. To identify the link protein by Western blotting, the proteins on the gel were transferred to a sheet of nitrocellulose and immunostained with the 9/30/8-A-4 monoclonal antibody. (The monoclonal antibody, developed by Dr. B. Caterson, was obtained from the Developmental Studies Hybridoma Bank under the auspices of the NICHD and maintained by the University of Iowa, Department of Biological Sciences, Iowa City, IA 52242.) This identity was further confirmed by NH2-terminal sequencing (Fig. 1)Citation . In tests of the biological activity of Metastatin, controls consisted of Metastatin mixed with an excess mass of hyaluronan (Lifecore, Chaska, MN) or a heat-inactivated preparation made by placing it in a boiling water bath for 30 min.



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Fig. 1. SDS-PAGE and NH2-terminal analysis of Metastatin. Lane 1, molecular mass markers; Lane 2, Metastatin stained with Coomassie blue; Lane 3, Western blot of Metastatin immunostained with an antibody against the link protein. The fragment of aggrecan migrated as a diffuse band at ~85 kDa, whereas the truncated link protein was at 38 kDa. NH2-terminal sequence analysis of the 38-kDa band indicated that the first 24 amino acids of the link protein have been cleaved and is indicated on the schematic diagram.

 
Endothelial and Tumor Cell Lines.
HUVECs4 were obtained from the Tumor Bank of the Lombardi Cancer Center (Georgetown University, Washington, DC). ABAEs were kindly provided by Dr. Luyuan Li (Lombardi Cancer Center), and BRECs were provided by Dr. Rosemary Higgins (Pediatrics, Georgetown University). These endothelial cells were cultured in 90% DMEM, 10% fetal bovine serum, and 10 ng/ml bFGF. The B16BL6 melanoma tumor line was obtained from the National Cancer Institute Central Repository (Frederick, MD), TSU cells were obtained from the American Type Culture Collection (Rockville, MD), and Lewis lung carcinoma cells were kindly supplied by Dr. Michael O’Reilly (Children’s Hospital, Boston, MA). The tumor cells were grown in 90% DMEM, 10% fetal bovine serum, and 2 mM L-glutamine. For the mouse metastasis assays, cells were generally used between passages 6 and 18.

Mice.
Specific pathogen-free, male, 6–8-week-old C57Bl/6 mice were obtained from The Jackson Laboratory (Bar Harbor, ME). Animals were cared for and treated in accordance with the procedures outlined in the Guide for the Care and Use of Laboratory Animals (NIH Publication No. 86-23). Animals were housed in a pathogen-free environment and provided with sterilized animal chow (Harlan Sprague Dawley, Indianapolis, IN) and water ad libitum.

Mouse Metastasis Model System.
For the experimental melanoma model, mice were inoculated i.v. in the lateral tail vein with B16Bl6 cells (5 x 104 cells/animal) on day 0. Treatment was initiated on day 3 with 5 (0.2 mg/kg), 15 (0.6 mg/kg), and 49 µg (2 mg/kg) of Metastatin and continued daily until animals were sacrificed on day 14. After euthanasia, the lungs were removed, and surface metastatic lesions were enumerated under a dissecting microscope.

Mice were also inoculated with Lewis lung carcinoma cells, which aggressively form pulmonary metastases. Mice were injected i.v. in the lateral tail vein with 2.5 x 105 cells/animal (day 0), and beginning on day 3, the Metastatin was administered by daily i.p. injections of 15 (0.6 mg/kg) and 49 µg (2 mg/kg) or by three i.v. injections of 100 µg (4 mg/kg) on days 1, 3, and 5. Animals were euthanized, and their lungs were removed and weighed. To obtain the lung weight gain, the average lung weight of nontreated mice (0.2 g) was subtracted from that of the treated animals.

The number of pulmonary metastases and lung weight gains were reported as mean ± SD, and the differences were compared using Student’s t test. The groups were considered to be different when the probability (P) value was <0.05.

Chicken Chorioallantoic Membrane Assays.
To measure angiogenesis, a chick chorioallantoic membrane assay was performed using a modification of the methods of Brooks et al. (17) . For this, holes were drilled in the tops of 10-day-old chicken eggs to expose the chorioallantoic membranes, and filter discs (0.5 cm in diameter) containing 20 ng of human recombinant VEGF [20 µl (1 µg/ml); Pepro, Rocky Hill, NJ] were placed on the surface of each chorioallantoic membrane (day 0). The holes were covered with parafilm, and the eggs were incubated at 37°C in a humidified atmosphere. One day later, the eggs were given injections (via a blood vessel in the chorioallantoic membrane using a 30-gauge needle) of the various substances [Metastatin (80 µg/egg) or controls consisting of PBS or heat-inactivated Metastatin]. Three days later (day 4), the chorioallantoic membranes and associated discs were cut out and immediately immersed in 3.7% formaldehyde. For computer-assisted image analysis, the discs were divided into quarters with fine wires, and the blood vessels in each quarter were digitally photographed and analyzed by an Optimas 5 program to calculate the vessel area and length normalized to the total area measured. The means and the SEs were calculated from all quadrants within each group, and the statistical significance was determined by Student’s t test. Twelve or more eggs were used for each sample point.

For the growth of xenografts on the chorioallantoic membrane, holes were cut into the sides of 10-day-old eggs exposing the membrane (day 0), and then 1 x 106 B16BL6 or TSU cells were applied to the membranes. Two days later, the eggs were given i.v. injections of the various substances. On day 7, the tumor masses were fixed in formalin, dissected free from the normal membrane tissue, and weighed.

Cell Growth Assays.
To determine the effects of Metastatin on cell growth, the cell lines were subcultured into 24-well dishes at a density of approximately 5 x 105 cells/well for the endothelial cell lines (HUVEC, ABAE, and BREC) and 5 x 104 cells/well for tumor cell lines (B16BL6, TSU, and Lewis lung carcinoma). For the dose-response experiments, the medium was changed every other day, and at the end of 6 days, the cells were released with 0.5 mM EDTA in PBS, and the cell number was determined with a Coulter counter (Hialeah, FL).

ELISA Assay for Hyaluronan.
Cells were grown to confluence in 24-well dishes, and the conditioned medium was collected, incubated with a biotinylated version of the Metastatin (16) , and then transferred to plates precoated with hyaluronan (umbilical cord; Sigma). The hyaluronan present in the conditioned medium interacts with the biotinylated Metastatin so that less of it will be left to bind to hyaluronan attached to the plate. At the end of the incubation, the plates were washed, and the amount of biotinylated Metastatin remaining attached was determined by incubating the plates with streptavidin coupled to peroxidase (Kirkegard & Perry, Gaithersburg, MD) followed by a soluble substrate for peroxidase. The amount of hyaluronan in the conditioned medium was calculated by comparison with a standard curve with known amounts of hyaluronan (16) .

Wound Migration Assay.
A suspension of HUVECs (5 x 105 cells in 5 ml of 98% M199 and 2% fetal bovine serum) was added to 60-mm tissue culture plates that had been precoated with gelatin (2 ml of 1.5% gelatin in PBS, 37°C, overnight) and allowed to grow for 3 days to confluence. An artificial "L"-shaped wound was generated in the confluent monolayer with a sterile razor blade by moving the blade down and across the plate. Plates were then washed with PBS, and 2 ml of PBS were added to each plate along with 2 ml of sample in M199 and 2% fetal bovine serum in the presence and absence of 5 ng/ml bFGF. After an overnight incubation, the plates were treated with Diff-Quik for 2 min to fix and stain the cells. The number of cells that migrated were counted under x200 magnification using a 10-mm micrometer over a 1 cm distance along the wound edge. Ten fields for each plate were counted, and an average for the duplicate was calculated.


    RESULTS
 Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Characterization of Metastatin.
Metastatin was isolated from bovine nasal cartilage by affinity chromatography on hyaluronan-Sepharose. As shown in Fig. 1Citation , Metastatin consisted of two molecular factions as determined by SDS-PAGE, a sharp band at 38 kDa that corresponds to the link protein, and a diffuse band at approximately 85 kDa that represents a tryptic fragment of the aggrecan core protein (5 , 15 , 16) . The diffuse nature of this latter fraction is probably due to variations in the degree of glycosylation and glycosaminoglycan content. The identity of the link protein was verified by immunoblotting with a specific monoclonal antibody against this protein (Fig. 1)Citation . In addition, NH2-terminal sequence analysis of the 38-kDa band revealed that the purified protein was missing the first 24 amino acids. Previous studies have shown that this complex binds to hyaluronan with high affinity and specificity (5 , 16) . Indeed, a biotinylated version of the preparation has been widely used as a histochemical stain to localize hyaluronan in tissue sections (5 , 16) .

Because cartilage is known to contain various protease inhibitors, which may contribute to its antitumor properties (18) , we wanted to determine whether Metastatin possessed such attributes. For this reason, we used a chromogenic assay (Diapharma Group, Inc., West Chester, OH) to assess the effect of Metastatin on the following enzymes: (a) trypsin; (b) chymotrypsin; (c) plasmin; and (d) elastase. At concentrations as high as 100 µg/ml, Metastatin did not inhibit the activity of any of the enzymes tested (data not shown).

Effect of Metastatin on Metastatic Tumors.
In initial experiments, we found that Metastatin was effective at inhibiting pulmonary metastases of B16BL6 cells. When mice were given daily i.p. injections of Metastatin 3 days after tumor inoculation, lung metastases were strikingly reduced (Fig. 2Citation A). Fig. 2Citation B shows that the number of surface lung metastases (>0.5 mm) in the mice treated with 15 and 49 µg Metastatin/day were reduced by more than 80%. The doseresponse curve shown in Fig. 2CCitation was constructed from two independent experiments and shows that Metastatin decreased the number of metastatic colonies in a dose-dependent manner with an ED50 of approximately 10 µg (0.4 mg/kg). Significantly, when Metastatin preparations were premixed with macromolecular hyaluronan, the antimetastatic activity was blocked, and the mean number of surface pulmonary metastases was comparable to that seen in control mice (Fig. 2B)Citation . This suggests that the ability of Metastatin to bind hyaluronan is required for its anti-tumor activity.



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Fig. 2. Effect of Metastatin on B16BL6 melanoma metastasis. B16BL6 melanoma cells were injected into the tail veins of C57Bl/6 mice, and 3 days later, the mice were injected i.p. with increasing doses of Metastatin. After 14 days, the lungs were removed, and surface pulmonary metastases were counted. A, the lungs from control animals had a greater number of metastases than those from the Metastatin (49 µg)-treated animals. B, the number of pulmonary metastases larger than 0.5 mm is plotted against the concentration of Metastatin injected. Metastatin inhibits the number of metastases, and the addition of hyaluronan to Metastatin blocked its inhibitory activity. The values shown are the mean of at least five mice/group; bars, SD. C, this dose-response curve was derived from two independent experiments (n = 5 for each point) and shows the ratio of pulmonary metastasis in the test and control animals (T/C) as a function of the Metastatin dose.

 
Similar results were obtained with the Lewis Lung carcinoma cell line, which is a more aggressive mouse tumor model. As shown in Fig. 3Citation , A and B, Metastatin inhibited pulmonary metastasis of Lewis lung carcinoma cells in a dose-related fashion, as reflected in the weight gain of the lungs. Furthermore, Metastatin was effective when given by two different routes, i.p. and i.v. (Fig. 3Citation , B and C).



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Fig. 3. Inhibition of pulmonary metastasis of Lewis lung carcinoma cells. Lewis lung carcinoma cells were injected into the tail veins of C57Bl/6 mice, and 3 days later, mice were treated with PBS or Metastatin. Once the treatment was stopped, animals were euthanized, and lungs were removed and weighed. A, shows representative lungs from control and treated animals and illustrates that Metastatin lowers the tumor burden. B, Metastatin injected i.p. daily beginning on day 4 decreased the relative lung weights in a dose-dependent fashion. C, the weight of the lungs in animals was also decreased when Metastatin was administered by three separate i.v. injections (100 µg/injection on days 1, 3, and 5). The values shown are the mean of at least five mice/group; bars, SD.

 
Effect of Metastatin on in Vitro Cell Proliferation and Migration.
In the next series of experiments, we wanted to determine whether Metastatin has any effect on the growth of either endothelial or tumor cells in tissue culture. For these experiments, the cells were grown in the presence of varying concentrations of Metastatin for 6 days, and then the final cell numbers were determined. Metastatin inhibited the proliferation of the endothelial cell lines HUVEC, ABAE, and BREC (Fig. 4Citation A) and two of the tumor cell lines (B16BL6 and Lewis lung carcinoma cells) but had no effect on the TSU cells (Fig. 4Citation B). Similar results were obtained when proliferation was monitored by incorporation of bromodeoxyuridine (data not shown). It is important to note that the growth inhibition of B16BL6 cells was partially blocked when the preparation of Metastatin was premixed with an excess of hyaluronan (Fig. 4Citation B).



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Fig. 4. The effects of varying concentrations of Metastatin on the growth of cultured cells. The cell lines were cultured in 24-well dishes in complete medium containing the indicated amounts of Metastatin, with medium changes ever other day. After 6 days, the cells were harvested with a solution of EDTA in PBS, and the cell numbers were determined with a Coulter counter. A, a dose-response curve is shown for the effects of Metastatin on the growth of the endothelial cell lines HUVEC, ABAE, and BREC. In each case, the growth of the cells was inhibited by Metastatin. B, a dose-response plot is shown for the tumor cell lines B16BL6 and TSU. Whereas Metastatin inhibited the growth of the B16BL6 cells, it had little or no effect on the TSU cells. The addition of an equal mass of hyaluronan to the Metastatin significantly reduced its effect on the proliferation of B16BL6 cells.

 
One possible explanation for the lack of TSU cell sensitivity to Metastatin could be the amount of hyaluronan that they secrete because it has an inhibitory effect. To test this possibility, conditioned media from confluent cultures of the different cell lines were collected and analyzed for hyaluronan by a modified ELISA. TSU cells were found to secrete significantly larger amounts of hyaluronan into the medium than the other cell lines (7 µg/ml versus <0.5 µg/ml, respectively). Indeed, this level of hyaluronan would be sufficient to block the effects of added Metastatin.

We also examined the effects of Metastatin on the migration of endothelial cells, another important factor in the process of angiogenesis (19) . In this assay, we examined the effect of Metastatin on the migration of HUVECs using the wound migration assay. Fig. 5Citation shows that at a concentration of 10 µg/ml, Metastatin inhibited the migration of HUVECs by 50% as compared with controls treated with bFGF alone. Again, similar results were obtained when migration was monitored using Nucleopore filters (data not shown).



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Fig. 5. Dose-dependent inhibitory effect of Metastatin on the migration of endothelial cells. HUVECs were grown to confluence on gelatin-coated culture plates, wounded with a sterile razor blade, and induced to migrate with bFGF in the presence of varying amounts of Metastatin. The number of cells that migrated were enumerated using a micrometer and microscope at x200 magnification.

 
Effect of Metastatin on VEGF-induced Angiogenesis.
The fact that Metastatin could inhibit both the growth and migration of endothelial cells in vitro suggested that it might also be able to block angiogenesis in vivo. To test this possibility, we examined the effect of Metastatin on angiogenesis induced in the chick chorioallantoic membrane. In this assay, filter papers containing recombinant human VEGF were placed on the chorioallantoic membrane of 10-day-old eggs, which were then given a single i.v. injection of the Metastatin or control preparations. Three days later, the extent of vascularization in the region of the filters was determined by computer-assisted image analysis. As shown in Fig. 6Citation , treatment with Metastatin reduced both the length and area of vessels as compared with the control group, suggesting that Metastatin does indeed have the ability to block VEGF-induced angiogenesis.



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Fig. 6. Effect of Metastatin on VEGF-induced angiogenesis. The top of air sacs of 10-day-old chicken eggs were opened, exposing the chorioallantoic membranes, and filter discs containing 20 ng of VEGF were applied. The treated group was then injected i.v. with Metastatin (80 µg/egg), and the control group did not receive injections. The chorioallantoic membranes and associated discs were cut out on day 3 and analyzed by computer-assisted image analysis as described in "Materials and Methods". Metastatin had a significant inhibitory effect on both the (A) vessel length index and (B) vessel area index.

 
Inhibition of Tumor Growth on the Chorioallantoic Membrane.
To further explore the antitumor activity of Metastatin, we examined its effect on the growth of B16BL6 and TSU cells on the chicken chorioallantoic membrane. Tumor cells were applied to the chorioallantoic membranes of 10-day-old chicken embryos and allowed to grow for 1 week. Pilot experiments revealed that after inoculation with 106 cells, the take rate was almost 100% and resulted in xenografts with weights from 50–150 mg in 7 days. However, when the inoculated eggs were given a single i.v. injection of the Metastatin, the growth of the B16BL6 and TSU xenografts was greatly inhibited (Fig. 7)Citation . Again, this inhibitory effect was abolished if the preparation of Metastatin was heat inactivated or preincubated with its ligand, hyaluronan (Fig. 7Citation B). It is important to note that Metastatin did not appear to adversely affect the development of the chicken embryos.



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Fig. 7. Effect of Metastatin on the growth of tumor cells on the chicken chorioallantoic membrane. The top of the air sacs of 10-day-old chicken eggs were opened, exposing the chorioallantoic membrane, and pellets containing B16BL6 melanoma or TSU prostate tumor cells were placed on the membrane. On day 3, the embryos were given a single i.v. injection of PBS or Metastatin (80 µg). The tumors and associated chorioallantoic membranes were removed on day 6 and weighed. A and C, examples of the B16BL6 and TSU xenografts from eggs treated with PBS, Metastatin, or heat-denatured Metastatin. B and D, the weights of B16BL6 and TSU xenografts from eggs treated with Metastatin and control preparations are shown.

 

    DISCUSSION
 Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
In this study we report that Metastatin, a cartilage-derived hyaluronan-binding complex consisting of proteolytic fragments of bovine link protein and aggrecan, is able to block the growth and metastasis of tumor cells under the following conditions: (a) a single i.v. injection of Metastatin into the chorioallantoic membrane of chicken embryos inhibited the growth of B16BL6 mouse melanoma cells and TSU human prostate cancer cells; (b) multiple i.p. injections of Metastatin prevented the experimental metastasis of B16BL6 and Lewis lung carcinoma cells to the lungs of mice; and (c) three i.v. injections of Metastatin were sufficient to inhibit the formation of Lewis lung carcinoma metastasis. In each case, Metastatin did not have an obvious detrimental effect on the host and was neutralized by complexing with soluble hyaluronan.

Metastatin is a member of a family of hyaluronan-binding proteins that also includes CD44, tumor necrosis factor-stimulated gene 6 (TSG-6), versican, neurocan, and brevican (20) . Interestingly, Metastatin is similar to other factors that influence angiogenesis in that it is a fragment of a larger complex. For example, Angiostatin is a fragment of plasminogen, Endostatin represents a fragment of collagen XVIII, and serpin consists of a fragment of antithrombin (21, 22, 23, 24) . It is possible that the production of the peptide fragments is part of a feedback loop important in the down-regulation of angiogenesis.

In addition to Metastatin, a number of other antiangiogenic factors have been isolated from cartilage. Indeed, cartilage has been extensively studied as a source of molecules that could account for its avascular nature. Langer et al. (25) first reported a bovine cartilage fraction isolated by guanidine extraction and purified by trypsin affinity chromatography that inhibited tumor-induced vascular proliferation. In addition, Moses et al. (26) have recently isolated Troponin I from veal scapulae, which was shown to have antitumor and antiangiogenic properties. Lee and Langer (27) have described a guanidine-extracted factor from shark cartilage that inhibited angiogenesis and suppressed tumor vascularization. Similarly, Moses et al. (18) isolated a factor from cultures of scapular chondrocytes that inhibited angiogenesis in the chicken chorioallantoic membrane and appeared to be a protease inhibitor. However, it is likely that our preparation of Metastatin acts through a distinct mechanism because it has no detectable antiprotease activity and is inhibited by the addition of hyaluronan. It is tempting to speculate that Metastatin may contribute to the avascular nature of cartilage. Along these lines, we have previously found that hypertrophic chondrocytes produce large amounts of free hyaluronan, which may neutralize the effects of Metastatin in this region and thereby allow blood vessels to invade (28) .

The results of this study suggest that Metastatin has antiangiogenic properties as demonstrated by its ability to block VEGF-induced formation of blood vessels in the chicken chorioallantoic membrane. The antiangiogenic effect of Metastatin was also consistent with our finding that it blocked both the proliferation and migration of cultured endothelial cells. Whereas Metastatin can directly attach tumor cells, we believe that most of its antitumor activity is due to its inhibition of angiogenesis because after its injection, the first cells that it would encounter are the endothelial cells, which would be exposed to the highest concentration. In addition, this antiangiogenic mechanism is suggested by the fact that Metastatin blocked the growth of TSU cells in vivo (i.e., on the chicken chorioallantoic membrane) but had little or no effect on their proliferation in vitro. In this particular case, it seems likely that Metastatin was acting indirectly on the TSU tumor cells by blocking angiogenesis.

In other cases, the antitumor activity of Metastatin may be due to the combined action of direct killing of the tumor cells and the inhibition of angiogenesis. Indeed, Metastatin does appear to partially inhibit the growth of B16BL6 in tissue culture, and it could presumably have a similar effect in vivo. Because many blood vessels that are associated with tumors are leaky (29) , Metastatin may be able to escape the circulation to interact directly with the tumor cells and block their proliferation. Along these lines, a recent study by Maniotis et al. (30) has indicated that some tumors have the ability to form vasculature independent of endothelial cells. The tumor cells themselves appear to take on the characteristics of endothelial cells and are responsible for the formation of blood vessels. It is possible that such dual-acting tumor cells could also respond to Metastatin.

The biological effects of Metastatin appear to be closely linked to its ability to bind hyaluronan. If the preparation of Metastatin was premixed with hyaluronan, then this reversed its inhibitory effects on tumor growth in vivo and in vitro and its effects on the growth and migration of cultured endothelial cells. This indirectly suggests that Metastatin is binding to hyaluronan associated with the target cell. In the case of endothelial cells, particularly high levels of hyaluronan are localized to the tips of newly forming capillaries in the chicken chorioallantoic membrane and rabbit cornea (2 , 3) . A variety of other cell types show a similar relationship between proliferation and the production of hyaluronan (31, 32, 33, 34) . Whereas the hyaluronan present on proliferating tumor and endothelial cells could interact directly with Metastatin in the blood, the hyaluronan in other locations would not be exposed to high concentrations of the complex. Most normal cells would be protected by the fact that high concentrations of hyaluronan are present in connective tissues such as the dermis, lamina propria, and capsules (5 , 35 , 36) , which would help to neutralize the Metastatin that diffused into these regions. It is important to note that under normal physiological conditions, hyaluronan in the blood is maintained at low levels by the liver and lymphatic system (37 , 38) . Thus, the circulating Metastatin should retain its hyaluronan binding activity.

Cell surface hyaluronan may serve as a target for other inhibitors of angiogenesis and tumor growth. For example, Endostatin, a ~20-kDa fragment of the COOH-terminal of collagen XVIII that inhibits angiogenesis (21 , 22) , may also be able to bind hyaluronan, as suggested by the presence of specific structural motifs (39) . Secondly, a soluble, recombinant version of immunoglobulin fused with CD44 that binds to hyaluronan can inhibit the growth of human lymphoma cells that express CD44 in nude mice (40 , 41) . TSG-6, which is secreted by a variety of cells after stimulation with inflammatory cytokines, is able to both bind hyaluronan and block tumor cell growth (42) . In each of these cases, these factors may be interacting with hyaluronan on the surfaces of target cells to exert their effects on angiogenesis and tumor growth.

In preliminary studies, we have found that Metastatin induces apoptosis in the target cells. However, at present, the mechanism by which Metastatin is able to do this is unclear. One possibility is that after Metastatin has bound to hyaluronan on the cell surface, it is taken up by the cells into lysosomes, where it is broken down into smaller fragments that enter the cytoplasm and induce apoptosis, perhaps by interacting with the mitochondrial membrane. Alternatively, Metastatin could be interacting directly with the plasma membrane of the target cells, causing damage that in turn induces the apoptotic cascade. Clearly, future experiments will be directed toward elucidating the mechanism by which Metastatin induces apoptosis in the target cells.

In conclusion, we have found that Metastatin is able to block tumor growth in two model systems, and this effect depends on its ability to bind hyaluronan. Metastatin appears to target both tumor cells and endothelial cells that are involved in neovascularization. We postulate that during angiogenesis, the endothelial cells up-regulate their synthesis of hyaluronan, which then serves as a target for the injected Metastatin. Thus, Metastatin may represent a new type of antitumor agent, which targets cell surface hyaluronan.


    ACKNOWLEDGMENTS
 
We are grateful to Dr. Theresa LaVallee and Wendy Hembrough for their assistance with the migration assay.


    FOOTNOTES
 
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

1 Supported in part by the United States Army Medical Research and Materiel Command under DAMD1717-94-J-4284, DAMD17-98-1-8099, and DAMD17-99-1-9031. Additional support was obtained from the Susan G. Komen Foundation and NIH Grant R29CA71545. Back

2 These authors contributed equally to this work. Back

3 To whom requests for reprints should be addressed, at EntreMed, Inc., Medical Center Drive, Suite 200, Rockville, MD 20902. Phone: (301) 738-2494; Fax (301) 217-9594; E-mail shawng@entremed.com. Back

4 The abbreviations used are: HUVEC, human umbilical vein endothelial cell; ABAE, adult bovine aorta endothelial cell; BREC, bovine retinal endothelial cell; VEGF, vascular endothelial growth factor; bFGF, basic fibroblast growth factor. Back

Received 7/12/00. Accepted 11/28/00.


    REFERENCES
 Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Rooney P., Kumar S., Ponting J., Wang M. The role of hyaluronan in tumor neovascularization.. Int. J. Cancer, 60: 632-636, 1995.[Medline]
  2. Ausprunk D. H., Boudreau C. L., Nelson D. A. Proteoglycans in the microvasculature.. II. Histochemical localization in proliferating capillaries of the rabbit cornea. Am. J. Pathol., 103: 367-375, 1981.[Abstract]
  3. Ausprunk D. H. Distribution of hyaluronic acid and sulfated glycosaminoglycans during blood vessel development in the chick chorioallantoic membrane.. Am. J. Pathol., 177: 313-331, 1986.
  4. Mohamadzadeh M., DeGrendele H., Arizpe H., Estess P., Siegelman M. Proinflammatory stimuli regulate endothelial hyaluronan expression and CD44/HA-dependent primary adhesion.. J. Clin. Investig., 101: 97-108, 1998.[Medline]
  5. Green S. J., Tarone G., Underhill C. B. The distribution of hyaluronate and hyaluronate receptors in the adult lungs.. J. Cell Sci., 89: 145-156, 1988.
  6. Eggli P. S., Graber W. Association of hyaluronan with rat vascular endothelial and smooth muscle cells.. J. Histochem. Cytochem., 43: 689-697, 1995.[Abstract]
  7. Feinberg R. N., Beebe D. C. Hyaluronate in vasculogenesis.. Science (Washington DC), 220: 1177-1179, 1983.[Abstract/Free Full Text]
  8. West D. C., Hampson I. N., Kumar S. S. Angiogenesis induced by degradation products of hyaluronic acid.. Science (Washington DC), 228: 1324-1326, 1985.[Abstract/Free Full Text]
  9. Deed R. P., Rooney P. L., Kumar J. D., Norton J., Smith A., Freemont J., Kumar S. Early-response gene signaling is induced by angiogenic oligosaccharides of hyaluronan in endothelial cells. Inhibition by non-angiogenic, high-molecular-weight hyaluronan. Int. J. Cancer, 71: 251-256, 1997.[Medline]
  10. Banerjee S. D., Toole B. P. Hyaluronan-binding protein in endothelial cell morphogenesis.. J. Cell Biol., 119: 643-652, 1992.[Abstract/Free Full Text]
  11. Griffioen A. W., Goenen M. J. H., Damen C. A., Hellwig S. M. M., van Weering D. H. J., Vooys W., Blijham G. H., Groenewegen G. CD44 is involved in tumor angiogenesis; an activation antigen on human endothelial cells.. Blood, 90: 1150-1159, 1997.[Abstract/Free Full Text]
  12. Banerji S., Ni J., Wang S-X., Clasper S., Su J., Tammi R., Jones M., Jackson D. G. LYVE-1, a new homologue of the CD44 glycoprotein, is a lymph-specific receptor for hyaluronan.. J. Cell Biol., 144: 789-801, 1999.[Abstract/Free Full Text]
  13. Culty M., Nguyen H. A., Underhill C. B. The hyaluronan receptor (CD44) participates in the uptake and degradation of hyaluronan.. J. Cell Biol., 116: 1055-1062, 1992.[Abstract/Free Full Text]
  14. Culty M., Shizari M., Thompson E. W., Underhill C. B. Binding and degradation of hyaluronan by human breast cancer cell lines expressing different forms of CD44: correlation with invasive potential.. J. Cell. Physiol., 160: 275-286, 1994.[Medline]
  15. Tengblad A. Affinity chromatography on immobilized hyaluronate and its applications to the isolation of hyaluronate binding proteins from cartilage.. Biochim. Biophys. Acta., 578: 281-289, 1979.[Medline]
  16. Underhill C. B., Zhang L. Analysis of hyaluronan using biotinylated hyaluronan-binding proteins.. Methods Mol. Biol., 137: 441-447, 1999.
  17. Brooks P. C., Silletti S., von Schalscha T. L., Friedlander M., Cheresh D. A. Disruption of angiogenesis by PEX, a noncatalytic metalloproteinase fragment with integrin binding activity.. Cell, 92: 391-400, 1998.[Medline]
  18. Moses M. A., Sudhalter J., Langer R. Isolation and characterization of an inhibitor of neovascularization from scapular chondrocytes.. J. Cell Biol., 119: 473-482, 1992.
  19. Ausprunk D. H., Folkman J. Migration and proliferation of endothelial cells in preformed and newly formed blood vessels during tumor angiogenesis.. Microvasc. Res., 14: 53-65, 1977.[Medline]
  20. Neame P. J., Barry F. P. The link protein.. Experientia (Basel), 49: 393-402, 1993.
  21. Folkman J., Shing Y. Angiogenesis.. J. Biol. Chem., 267: 10931-10934, 1992.[Free Full Text]
  22. O’Reilly M. S., Boehm T., Shing Y., Fukai N., Vasios G., Lane W. S., Flynn E., Birkhead J. R., Olsen B. R., Folkman J. Endostatin.. An endogenous inhibitor of angiogenesis and tumor growth. Cell, 88: 277-285, 1997.[Medline]
  23. O’Reilly M. S., Holmgren L., Shing Y., Chen C., Rosenthal R. A., Moses M., Lane W. S., Cao Y., Sage E. H., Folkman J. Angiostatin.. A novel angiogenesis inhibitor that mediates the suppression of metastases by a Lewis lung carcinoma. Cell, 79: 315-328, 1994.[Medline]
  24. O’Reilly M. S., Pirie-Sheperd S., Lane W. S., Folkman J. Antiangiogenic activity of the cleaved conformation of the serpin antithrombin.. Science (Washington DC), 285: 1926-1928, 1999.[Abstract/Free Full Text]
  25. Langer R., Brem H., Falterman K., Klein M., Folkman J. Isolations of a cartilage factor that inhibits tumor neovascularization.. Science (Washington DC), 193: 70-72, 1976.[Abstract/Free Full Text]
  26. Moses M. A., Wiederschain D., Wu I., Fernandez C. A., Ghazizadeh V., Lane W. S., Flynn E., Sytkowski A., Tao T., Langer R. Troponin I is present in human cartilage and inhibits angiogenesis.. Proc. Natl. Acad. Sci. USA, 96: 2645-2650, 1999.[Abstract/Free Full Text]
  27. Lee A., Langer R. L. Shark cartilage contains inhibitors of tumor angiogenesis.. Science (Washington DC), 221: 1185-1187, 1983.[Abstract/Free Full Text]
  28. Pavasant P., Shizari M., Underhill C. B. Distribution of hyaluronan in the epiphysial growth plate: Turnover by CD44 expressing osteoprogenitor cells.. J. Cell Sci., 107: 2669-2677, 1994.[Abstract]
  29. Dvorak H. F., Nagy J. A., Dvorak J. T., Dvorak A. M. Identification and characterization of the blood vessels of solid tumors that are leaky to circulating macromolecules.. Am. J. Pathol., 133: 95-109, 1988.[Abstract]
  30. Maniotis A. J., Folberg R., Hess A., Seftor E. A., Gardner L. M. G., Pe’er J., Trent J. M., Meltzer P. S., Hendirx M. J. Vascular channel formation by human melanoma cells in vivo and in vitro: vasculogenic mimicry. Am. J. Pathol., 155: 739-752, 1999.[Abstract/Free Full Text]
  31. Main N. Analysis of cell-growth-phase-related variation in hyaluronate synthase activity of isolated plasma-membrane fractions of cultured human skin fibroblasts.. Biochem. J., 237: 333-342, 1986.[Medline]
  32. Tomida M., Koyama H., Ono T. Induction of hyaluronic acid synthetase activity in rat fibroblasts by medium change of confluent cultures.. J. Cell. Physiol., 86: 121-130, 1975.[Medline]
  33. Hronowski L., Anastassiades T. P. The effect of cell density on net rates of glycosaminoglycan synthesis and secretion by cultured rat fibroblasts.. J. Biol. Chem., 255: 10091-10099, 1980.[Abstract/Free Full Text]
  34. Matuoka K., Namba M., Mitsui Y. Hyaluronate synthetase inhibition by normal and transformed human fibroblasts during growth reduction.. J. Cell Biol., 104: 1105-1115, 1987.[Abstract/Free Full Text]
  35. Alho A. M., Underhill C. B. The hyaluronate receptor is preferentially expressed on proliferating epithelial cells.. J. Cell Biol., 108: 1557-1565, 1989.[Abstract/Free Full Text]
  36. Underhill C. B. The interaction of hyaluronate with the cell surface: the hyaluronate receptor and the core protein.. CIBA Found. Symp., 143: 87-106, 1989.[Medline]
  37. Fraser J. R. E., Appelgren L. E., Laurent T. C. Tissue uptake of circulating hyaluronic acid.. Cell Tissue Res., 233: 285-293, 1983.[Medline]
  38. Laurent T. C., Fraser J. R. E. The properties and turnover of hyaluronan. Laurent, removal of HA from the blood. CIBA Found. Symp., 124: 9-29, 1986.
  39. Hobenester E., Sasaki T., Olsen B. R., Timpl R. Crystal structure of the angiogenesis inhibitor endostatin at 1.5 A resolution.. EMBO J., 17: 1656-1664, 1998.[Medline]
  40. Sy M-S., Guo Y. J., Stamenkovic I. Inhibition of tumor growth in vivo with a soluble CD44-immunoglobulin fusion protein.. J. Exp. Med., 176: 623-627, 1992.[Abstract/Free Full Text]
  41. Yu Q., Toole B. P., Stamenkov I. Induction of apoptosis of metastatic mammary carcinoma cells in vivo by disruption of tumor cell surface CD44 function.. J. Exp. Med., 186: 1985-1996, 1997.[Abstract/Free Full Text]
  42. Wisniewski H. G., Hua J-C., Poppers D. M., Naime D., Vilcek J., Cronstein B. N. TSG-6, a glycoprotein associated with arthritis, and its ligand hyaluronan exert opposite effects in a murine model of inflammation.. J. Immunol., 156: 1609-1615, 1996.[Abstract]



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