| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Advances in Brief |
Laboratoire dOncologie et Imagerie des Tumeurs Solides, Faculté de Médecine de Bobigny, Université Paris 13, 93017 Bobigny Cedex [R. B-Y., Y. K., A. M. R., R. V., M. C.]; Service dAnatomie Pathologie, 93017 Bobigny Cedex [A. M.]; Laboratoire de Recherche sur les Macromolécules, Centre National de la Recherche Scientifique, URA 502, Université Paris-Nord, 93430 Villetaneuse [J. J.]; and Institut National de la Santé et de la Recherche Médicale U353, Institut dHématologie, Hôpital Saint-Louis, 75010 Paris [C. S., H. L.] France
| ABSTRACT |
|---|
|
|
|---|
| Introduction |
|---|
|
|
|---|
We have reported previously (5) that CMDB73 displays an in vitro growth-inhibitory activity in breast tumoral cells. A positive correlation was found between the inhibition of cell proliferation and the overall content of benzylamide (5) . Growth inhibition was associated with a decrease in the proportion of S-phase cells and an accumulation of G1 phase cells (5) . CMDB7 specifically inhibited the mitogenic effect and receptor binding of angiogenic growth factors, such as FGF-2, FGF-4, platelet-derived growth factor BB, and transforming growth factor ß1, by forming complexes with them (6, 7, 8) and prevented endothelial cell proliferation and migration (7) . In vivo studies demonstrated that growth of MCF-7ras (8) and FGF-4 transfected HBL100 cell (7) tumors in nude mice was blocked by CMDB7 treatment, and histological analysis showed much less neovascularization in these tumors.
We have now investigated the effect of CMDB7 on FGF-2-induced angiogenesis in a matrigel angiogenic assay. Estrogen receptor-negative MDA-MB435 breast carcinoma cells were xenografted into nude mice to determine whether CMDB7 might have therapeutic utility in the prevention or treatment of metastatic breast cancer. After injection into m.f.p., these cells gave rise to metastases in lung organ and thus provided an experimental model for the metastasis of a highly aggressive human breast carcinoma (9) .
| Materials and Methods |
|---|
|
|
|---|
Cell Line and Cell Cultures.
MDA-MB435 is an estrogen receptor-negative cell line isolated from the pleural effusion of a patient with breast carcinoma (11)
. The cells were grown in DMEM (Life Technologies, Gaithersburg, MD) supplemented with 10% FCS, 2 mM L-glutamine, 50 IU/ml penicillin, and 50 µg/ml streptomycin (Life Technologies) at 37°C in a humidified atmosphere containing 5% CO2. Cells were routinely passed once a week at a 1:10 split ratio.
Murine Angiogenesis Assay.
Angiogenesis was assayed as the growth of blood vessels from s.c. tissue into a solid gel of reconstituted basement membranes containing the test sample (12)
. Matrigel (11.46 mg/ml; Becton Dickinson Laware, Bedford, MA) in liquid form at 4°C was mixed with FGF-2 (1 µg) with or without different concentrations of CMDB7 and injected into the abdominal s.c. tissue of 5 mice/group. At body temperature, matrigel rapidly solidified, thereby trapping the factor, assuring its slow release, and prolonging exposure of surrounding tissues. Mice were killed 2 weeks later, and the matrigel plugs were exposed for photography. NIH image analysis (see "Image Analysis") was applied to quantitate the vascularization in each tissue section, the extent of which is expressed as the percentage area of labeled endothelial cells ± SE on each slide.
Animal Model for Metastases.
Female athymic nude mice (nu/nu), 3 weeks old, were obtained from Janvier Laboratory (Le-Genest-St-Isle, France). Animals were kept in a temperature-controlled room on 12 h/12 h light/dark schedule with food and water ad libitum. MDA-MB435 cells were grown in DMEM supplemented with 10% FCS in T150 plates and harvested at 80% confluence. The m.f.p. has been shown to be a more favorable graft site for the growth of mouse mammary tumorsbecause of its good blood supply as compared with the subcutisand also for the dissemination of metastases from the m.f.p tumors (9)
. Mice were anesthetized with Metofane, and a 5-mm incision was made in the skin over the lateral thorax to expose the m.f.p. The inoculum (106 cells/0.1 ml) was injected into the tissue taking care to avoid the s.c. space. All of the mice developed tumors after about 1 week. CMDB7 treatment was initiated 2 weeks after cell inoculation, when tumors were well established (approximately 0.34 cm3). Mice (n = 42) were arbitrarily assigned to receive 0.1 ml of PBS s.c. (controls, n = 10) or CMDB7 injected s.c. close to the tumor at 50 (n = 8), 150 (n = 8), or 300 mg/kg/week (n = 8) or i.v. (i.v.) at 300 mg/kg/week (n = 8) for 10 weeks. Tumors were measured along two major axes with calipers. Tumor volume was calculated as follows:
![]() |
Tissue Preparation and Immunohistochemical Analysis.
Immediately after surgical resection, primary tumor specimens were weighed and cut into small pieces; fragments were fixed with 4% formalin processed to paraffin in the usual way, and 4-µm sections were stained with H&E. Endothelial cells were specifically stained with GSL-1 (Vector Laboratories, Burlingame, CA). The GSL-1 lectin binds specifically to galactosyl residues and thus labels the vascular endothelium in mice (13)
. Sections were deparaffinized and rehydrated. Endogenous peroxidase was inactivated with 3% H2O2 and washed in TBS (pH 7.6) followed by preincubation in FCS for 30 min at room temperature. The sections were then incubated for 45 min with biotinylated GSL-1 (0.01 mg/ml), washed with TBS, and treated for 30 min with avidin-peroxidase (Vector Laboratories), and washed again with TBS. The peroxidase was visualized by incubation for 10 min in 0.1 M acetate buffer (pH 5.2) containing 3% H2O2 and 3% 3-amino-9-ethylcarbazole. Finally, the slides were washed in distilled water and tap water, counterstained with hematoxylin, dehydrated, and coverslipped with Permount.
Image Analysis.
For each GSL-1-labeled section of control and CMDB7-treated tumors, five fields containing exclusively viable tumoral cells, as indicated by the hematoxylin stain, were selected randomly for analysis. Image analysis was performed on a Power Macintosh computer 8500/120 using the public domain NIH program.4
The endothelial cell area in each section was determined, with an experimental error of <5%, by quantifying those areas emitting an intensity of GSL-1 labeling above a given threshold level. The percentage area of endothelial cells was then calculated as the ratio of the labeled area:the total viewed area x 100; these values were then averaged for untreated (control) and treated-CMDB7 tumors.
Statistical analysis.
The results are presented as means ± SE. Multiple statistical comparisons were performed using ANOVA and the Mann-Whitney U tests in a multivariate linear model.
| Results |
|---|
|
|
|---|
|
|
|
|
No Toxicity of CMDB7 in Nude Mice.
The body weight of the inoculated mice (s.c. or i.v. injections) was not affected by CMDB7 at all of the doses tested after 10 weeks of treatment (data not shown). CMDB7 administrated i.v. or s.c. at 300 mg/kg produced no signs of toxicity such as diarrhea, infection, weakness, and lethargy. All of the 32 treated mice were alive at the end of 10 weeks.
| Discussion |
|---|
|
|
|---|
This study demonstrated a direct relationship between neovascularization within the primary tumors and the incidence of the percentage distant micrometastases. The results showed that lung micrometastases developed when the percentage area of endothelial cells reached a threshold of 2%. The prevalence of metastases increased as this area within the primary tumor increased. Our findings are consistent with previous studies (14, 15, 16, 17) that demonstrated a direct correlation between blood vessel density in primary tumors and their metastasis dissemination. Tumor microvessels often had fragmented basal membranes, which suggested that these vessels were structurally incomplete and leaky and, thus, that tumor cells could easily reach the circulation (14 , 18) .
Untreated mice had highly vascularized tumors, and microscopic lung metastases were observed in all of them. In contrast, CMDB7-treated mice exhibited a very low incidence of lung metastases. This low metastatic rate could reflect to the inhibited intratumoral angiogenesis because, at 50 mg/kg/week, CMDB7 very significantly blocked the growth of intratumoral vessels. CMDB7, when administrated i.v. is also active and, moreover, is the most clinically applicable. CMDB7 as well as other polyanionic polysaccharides such as heparin could be active when given p.o. (19) . Additional studies are necessary to confirm this hypothesis.
It has been reported that MDA-MB435 cells produce angiogenic factors, such as FGF-2 and vascular endothelial growth factor, that are detectable in their culture surpernatants (20) . Thus, CMDB7 could exert its antiangiogenic action by disrupting the autocrine and paracrine effects of growth factors released by the tumor cells.
We also demonstrated that CMDB7 had strong antiangiogenic and antimetastatic effects without inhibiting the primary tumor growth of xenografted MDA-MB435 tumors. This observation can be explained by the fact that MDA-MB435 mammary tumors grow slowly in vivo, and, thus, initial tumor growth may be independent of angiogenesis when the tumor size in
3 mm3 (1)
. However, for rapidly growing s.c. tumors, such as xenografted MCF-7ras (8)
and FGF-4-transformed human breast cells (HH9; Ref. 7
), CMDB7 inhibited tumor growth in parallel with less tumor angiogenesis.
The antiangiogenic activity of CMDB7 was further supported by the results of experiments using the model of tumor-free angiogenesis FGF-2-enriched matrigel. Indeed, inclusion of CMDB7 in the matrigel inhibited FGF-2-induced angiogenesis in a dose-dependent manner. These findings are in agreement with our earlier studies, which showed that CMDB7 inhibited the in vitro migration and proliferation of endothelial cells without acting on cell viability (7) . Thus, CMDB7 is cytostatic but not cytotoxic for endothelial cells. We reported previously (6) that CMDB7 inhibited HBL100 cell proliferation by interfering with the FGF-2 autocrine loop and that CMDB7 inhibited the paracrine mitogenic activity and receptor binding of FGF-2, FGF-4, transforming growth factor ß1, and platelet-derived growth factor BB (7 , 8) . Taken together, these new data confirmed that CMDB7, by blocking the activities of angiogenic growth factors as described in our previous reports, is a potent inhibitor of tumor angiogenesis and metastasis in vivo. We cannot exclude additional therapeutic effects of CMDB7 such as the inhibition of the number of tumor-associated macrophages infiltrating in vivo.
In conclusion, the data obtained with our model of human breast cancer highlighted: (a) the dependence of the incidence of distant metastasis development on the intratumoral angiogenesis of the primary tumors; and (b) the ability of CMDB7 to effectively inhibit angiogenesis in these xenografted tumors and prevent their distant metastasis to the lungs. Boehm et al. (21) demonstrated that a specific angiogenesis inhibitor (endostatin) did not induce drug resistance in three different types of transplantable murine tumors. Thus, CMDB7 and other antiangiogenic agents could be expected to be promising as novel pharmaceutic agents in cancer therapy, especially when the patients develop acquired drug resistance to cytotoxic drugs. CMDB7 could prove beneficial in preventing the occurrence of secondary metastases and in inducing tumor dormancy through its cytostatic action on endothelial cells.
| ACKNOWLEDGMENTS |
|---|
| FOOTNOTES |
|---|
1 This work was supported by the Fondation Martine-Midy (Paris, France). ![]()
2 To whom requests for reprints should be addressed, at Université Paris 13, Laboratoire dOncologie et Imagerie des Tumeurs Solides, Faculté de Médecine, 74, rue Marcel Cachin, 93017 Bobigny Cedex, France. Phone: 33-1-48-38-77-20; Fax: 33-1-48-38-77-29. E-mail: bagheri{at}smbh.univ-paris13.fr ![]()
3 The abbreviations used are: CMDB7, carboxymethyl benzylamide dextran; FGF-2, fibroblast growth factor 2; FGF-4, fibroblast growth factor 4; m.f.p., mammary fat pad; TBS, tris-buffered saline; GSL-1, Griffonia (Bandeiraea) simplicifolia lectin. ![]()
4 Developed at NIH and available on the internet at http://rsb.info.nih.gov/nih-image/. ![]()
Received 8/26/98. Accepted 12/17/98.
| REFERENCES |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
J. L. Cook, T. A. Miura, D. N. Ikle, A. M. Lewis Jr., and J. M. Routes E1A Oncogene-induced Sensitization of Human Tumor Cells to Innate Immune Defenses and Chemotherapy-induced Apoptosis in Vitro and in Vivo Cancer Res., June 15, 2003; 63(12): 3435 - 3443. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Hamma-Kourbali, R. Vassy, A. Starzec, V. Le Meuth-Metzinger, O. Oudar, R. Bagheri-Yarmand, G. Perret, and M. Crepin Vascular Endothelial Growth Factor 165 (VEGF165) Activities Are Inhibited by Carboxymethyl Benzylamide Dextran That Competes for Heparin Binding to VEGF165 and VEGF165{middle dot}KDR Complexes J. Biol. Chem., October 19, 2001; 276(43): 39748 - 39754. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Bagheri-Yarmand, Y. Hamma-Kourbali, P. Bissieres, J.-F. Morere, and M. Crepin Carboxymethyl Benzylamide Dextran and Tamoxifen Combination Inhibits Tumor Growth and Angiogenesis Clin. Cancer Res., June 1, 2001; 7(6): 1805 - 1811. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Yang, E. Baranov, X.-M. Li, J. W. Wang, P. Jiang, L. Li, A. R. Moossa, S. Penman, and R. M. Hoffman Whole-body and intravital optical imaging of angiogenesis in orthotopically implanted tumors PNAS, February 27, 2001; 98(5): 2616 - 2621. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Bagheri-Yarmand, R. K. Vadlamudi, R.-A. Wang, J. Mendelsohn, and R. Kumar Vascular Endothelial Growth Factor Up-regulation via p21-activated Kinase-1 Signaling Regulates Heregulin-beta 1-mediated Angiogenesis J. Biol. Chem., December 8, 2000; 275(50): 39451 - 39457. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Cancer Research | Clinical Cancer Research |
| Cancer Epidemiology Biomarkers & Prevention | Molecular Cancer Therapeutics |
| Molecular Cancer Research | Cancer Prevention Research |
| Cancer Prevention Journals Portal | Cancer Reviews Online |
| Annual Meeting Education Book | Meeting Abstracts Online |