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A simple, quantitative method for assessing angiogenesis and antiangiogenic agents using reconstituted basement membrane, heparin, and fibroblast growth factor.

BACKGROUND: Blood vessel growth is necessary for normal tissue homeostatis and contributes to solid tumor growth. Methods to quantitate neovascularization should be useful in testing biological factors and drugs that regulate angiogenesis or to induce a vascular supply to promote wound healing. EXPERIMENTAL DESIGN: An extract of basement membrane proteins (Matrigel) was found to reconstitute into a gel when injected subcutaneously into C57/BL mice and to support an intense vascular response when supplemented with angiogenic factors. RESULTS: New vessels and von Willebrand factor antigen staining were apparent in the gel 2-3 days after injection, reaching a maximum after 3-5 days. Hemoglobin content of the gels was found to parallel the increase in vessels in the gel allowing ready quantitation. Angiogenesis was obtained with both acidic and basic fibroblast growth factors and was enhanced by heparin. Several substances were tested for angiostatic activity in this assay by coinjection in Matrigel with fibroblast growth factor and heparin. Platelet-derived growth factor BB, interleukin 1-beta, interleukin-6, and transforming growth factor-beta were potent inhibitors of neovascularization induced by fibroblast growth factor. Tumor necrosis factor-alpha did not alter the response but was alone a potent inducer of neovascularization when coinjected with Matrigel and heparin. Consistent with the previously demonstrated importance of collagenase in mediating endothelial cell invasion, a tissue inhibitor of metalloproteinases that also inhibits collagenases was found to be a potent inhibitor of fibroblast growth factor-induced angiogenesis. CONCLUSIONS: Our assay allows the ready quantitative assessment of angiogenic and anti-angiogenic factors and should be useful in the isolation of endothelial cells from the capillaries that penetrate into the gel.

Angiogenesis Inducing Agents↗

Evaluation of in vitro reconstituted basement membrane assay to assess the invasiveness of tumor cells.

The crossing of tumor cells through basement membranes represents a critical step in the metastatic process. We have used a reconstituted basement membrane (matrigel) coated on filter in a Boyden chamber to assess the invasive potential of tumor and normal cells. No correlation was found between chemoinvasion in vitro and the metastatic potential in vivo. Normal human fibroblasts and murine 3T3 fibroblasts penetrated filters coated with matrigel. On the other hand, the tumoral cells (MCF7, MCF7 gpt, MCF7 ras, BeWo, JAR, NUC-1 cells) were unable to cross the matrix. Our results suggest that in our conditions, this widely used model to assess tumoral invasion does not provide a universal assay to test the invasiveness of tumor cells. Penetration of the matrigel appears to be related to chemotactic or haptotactic responses depending upon cell types. Our data emphasize the variability of molecular events associated with basement membrane invasion.

3T3 Cells↗

Inhibition of tumor cell invasion by a highly conserved peptide sequence from the matrix metalloproteinase enzyme prosegment.

The metastasis associated 72-kDa type IV collagenase is secreted as a latent proenzyme which is converted to an active 62-kDa form by autoproteolytic removal of an amino terminal profragment. The region immediately upstream from the cleavage site contains a highly conserved peptide sequence, MRKPRCGNPDV, which is present in all known members of the matrix metalloproteinase family. Evidence implicates the cysteine residue of this sequence as critical for maintenance of the latent form through coordination with the catalytic zinc atom of the active site. A synthetic peptide, TMRKPRCGNPDVAN (peptide 74), encompassing this conserved sequence, has been shown to inhibit the activated form of the 72-kDa type IV collagenase in vitro. In the present study we examine the ability of this peptide inhibitor to modulate tumor cell invasiveness. Peptide 74 and the control peptide 78, which contains a single substitution of serine for the "critical" cysteine residue, were added at 30 microM concentrations to the upper compartment of the Boyden chamber in the chemoinvasion assay using HT1080 and A2058 human tumor cells. In this assay a layer of reconstituted basement membrane, Matrigel, is coated onto chemotaxis filters and acts as a barrier to the migration of cells in the Boyden chambers. Only cells with invasive capacity can cross the Matrigel barrier. Peptide 74 containing the cysteine residue inhibited the invasion of both the HT1080 and A2058 cells through the Matrigel barrier; control peptide 78 was not inhibitory. Both peptides were shown to be without cytotoxic action and did not inhibit chemotaxis or affect cell number. This study demonstrates that addition of an excess peptide containing the matrix metalloproteinase prosegment inhibitory sequence can inhibit invasive activity at the cellular level and suggests that this may be a useful strategy to modulate tumor cell invasiveness in vivo.

Base Sequence↗

[Celastrol in the inhibition of neovascularization].

OBJECTIVE: To study the inhibition effect of celastrol on neovascularization. METHODS: The effect of celastrol on the in vitro proliferation of endothelial cell of vessel (ECV) was examined by MTT assay. The effect of celastrol on endothelial cell migration, tube formation on Matrigel and Chick chorioallantoic membrane angiogenesis was also examined. Matrigel plug assay was used to evaluate the effect of celastrol on angiogenesis in vivo. RESULTS: The proliferation of ECV was inhibited significantly by celastrol with IC(50) being 1.33 microg/ml. Celastrol inhibited endothelial cell migration and tube formation in a dose-dependent manner. Celastrol also inhibited angiogenesis both in Matrigel plug of mouse model and in chick chorioallantoic membranes. CONCLUSION: Celastrol, which can inhibit angiogenesis, could be developed as an antiangiogenic drug.

Angiogenesis Inhibitors↗

[The expression and clinical implication of gelatinase A in acute leukemic cells].

OBJECTIVE: To study the expression of gelatinase A (MMP2) in acute leukemic cells and its clinical implication. METHODS: The bone marrow samples from 46 acute leukemia patients were investigated by reverse transcription polymerase chain reaction (RT-PCR) and Gelatin Zymography method. Matrigel invasion assay was studied on U937, NB4, K562 and SHI1 cells in vitro. RESULTS: The expression of MMP2 was positive in 24 of 46 patients with AL (52.2%). In MMP2 positive and negative groups of AL, the extramedullary infiltration rates were 50.0% and 18.2% (P < 0.05), whilst the percentage of blast cell in peripheral white blood cells were (77.21 +/- 13.9)% and (62.95 +/- 17.2)% (P < 0.01), respectively. The positive expression of TIMP2 and MT1-MMP in 46 AL patients were 27 (58.7%) and 33 (71.7)%. The matrigel invasion assay suggested that MMP2 is involved in migration of leukemic cell through extracellular matrix (Matrigel). CONCLUSION: The active form of MMP2 might be essential to the egress of leukemic cells from bone marrow into peripheral blood, followed by an extramedullary infiltration.

Acute Disease↗

Multiple aspects of the phenotype of mammary epithelial cells transformed by expression of activated M-Ras depend on an autocrine mechanism mediated by hepatocyte growth factor/scatter factor.

Multiple aspects of the transformed phenotype induced in a murine mammary epithelial cell line scp-2 by expression of activated G22V M-Ras, including maintainance of cell number at low density, anchorage-independent growth, invasion of Matrigel, and secretion of matrix metalloproteinases (MMP) 2 and 9, were dependent on an autocrine mechanism. Conditioned medium from dense cultures of scp-2 cells expressing G22V M-Ras, but not from parental cells, induced activation of Erk and Akt in cells expressing G22V M-Ras, maintained the cell number and promoted anchorage-independent growth of cells expressing G22V M-Ras (although not the parental cells), and induced scattering of MDCK cells. The latter activities were blocked by neutralizing antibodies to hepatocyte growth factor/scatter factor (HGF/SF) and could be mimicked by HGF/SF. Anti-HGF/SF antibodies also inhibited invasion of Matrigel, and the production of MMP-2 and MMP-9, together with urokinase-type plasminogen activator, was secreted by G22V M-Ras scp-2 cells but not by parental cells. Invasion of Matrigel was blocked by an inhibitor of MMPs, BB94, and by the mitogen-activated protein kinase kinase 1/2 kinase inhibitor PD98059 but was only marginally affected by the phosphatidylinositol 3-kinase inhibitor LY294002. Autocrine HGF/SF was thus critical for expression of key features of the phenotype of mammary epithelial cells transformed by expression of activated M-Ras.

Animals↗

COX-2 overexpression increases motility and invasion of breast cancer cells.

Cyclooxygenase-2 (COX-2), an inducible enzyme involved in prostaglandin (including PGE(2)) biosynthesis, is overexpressed in several epithelial malignancies including breast cancer. We tested the hypothesis that COX-2 overexpression in breast cancer cells results in increased cell motility and invasion. COX-2 overproducing cells were generated by stable transfection of several human breast cancer cells with pSG5-COX2 vector. We confirmed the overexpression of COX-2 protein by western blotting, and by measuring PGE(2) in the medium with an immunoassay. We measured cell motility by counting the number of cells crossing an 8-micron pore size PET membrane, and cell invasion by counting the number of cells invading through a Matrigel-coated membrane that simulates basement membrane. COX-2 transfected MDA-231 cells produced 30-43-fold more PGE2 as compared to parental cells. COX-2 overexpression increased cell migration approximately 2.2-fold and cell invasion through Matrigel approximately 5.1-fold. Addition of 50 microM NS-398, a COX-2 inhibitor, inhibited Matrigel invasion of MDA-231 cells by 54% as compared to solvent confirming the role of COX-2 in cell invasion. It is known that an increase in cell migration and invasion can be brought about by cytoskeletal alterations and basement membrane degradation due to increased expression of pro-urokinase plasminogen activator (pro-uPA). To investigate the mechanism of our observed increase in cell invasion by COX-2, we found by western blotting that the level of pro-uPA was significantly higher (approximately 5-fold) in COX-2 transfected MDA-231 cells than untransfected MDA-231 cells. Similar to our observations in cell culture, we found evidence that increased COX-2 activity correlates with uPA in a mouse model of breast cancer metastasis to bone. In this study, we conclude that COX-2 overexpression in human breast cancer cells enhances cell motility and invasiveness thus suggesting a mechanism of COX-2 mediated metastasis.

Animals↗

[Involvement of AKT/eNOS in brain derived neurotrophic factor-induced angiogenesis].

OBJECTIVE: To investigate the signaling pathways involved in brain derived neurotrophic factor (BDNF) -induced angiogenesis and to provide a novel pathway to anti-angiogenesis in multiple myeloma. METHODS: The phosphorylation of AKT and endothelial NO synthase (eNOS) in human umbilical venous epithelial cells (HUVEC) were detected by Western blot. The angiogenic activity in vitro was evaluated by transwell migration assay and tube formation assay. BDNF-induced in vivo angiogenic activity was evaluated by Matrigel plug assay. The concentration of NO was detected by nitric acid deoxidizase assay. Cell apoptosis was detected by FITC-Annexin V/PI double staining and flow cytometry. RESULTS: BDNF activated the phosphatidylinositol-3-kinase (PI3K)/AKT/eNOS pathway in HUVEC in a time- and dose-dependent manner. BDNF-stimulated NO production was blocked by LY294002, a PI3K inhibitor. In vitro, BDNF induced HUVEC migration and tube formation on Matrigel, which could be significantly blocked by LY294002 and N(G)-nitro-L-arginine methyl ester (L-NAME) respectively; but BDNF induced HUVEC apoptosis could be blocked only by LY294002. In vivo, BDNF increased capillary ingrowth into subcutaneously implanted Matrigel plugs in mice, which could be significantly reduced in L-NAME treated mice. CONCLUSION: BDNF induces angiogenesis through the AKT/eNOS signaling kinase pathway. It may be a novel target for the anti-angiogenesis therapy for multiple myeloma.

Animals↗

Supernatants of acquired immunodeficiency syndrome-related Kaposi's sarcoma cells induce endothelial cell chemotaxis and invasiveness.

Kaposi's sarcoma (KS) in general, and acquired immunodeficiency syndrome-related KS (AIDS-KS) in particular, is a highly invasive and intensely angiogenic neoplasm of unknown cellular origin. We have recently established AIDS-KS cells in long term culture and reported the development of KS-like lesions in nude mice inoculated with these cells. Here, we have examined the in vitro invasiveness of basement membrane by AIDS-KS cells, as well as the effect(s) of their supernatants on the migration and invasiveness of human vascular endothelial cells. AIDS-KS cells were highly invasive in the Boyden chamber invasion assay and formed invasive, branching colonies in a 3-dimensional gel (Matrigel). Normal endothelial cells form tube-like structures on Matrigel. AIDS-KS cell-conditioned media induced endothelial cells to form invasive clusters in addition to tubes. KS-cell-conditioned media, when placed in the lower compartment of the Boyden chamber, stimulated the migration of human and bovine vascular endothelial cells across filters coated with either small amounts of collagen IV (chemotaxis) or a Matrigel barrier (invasion). Basic fibroblast growth factor could also induce endothelial cell chemotaxis and invasion in these assays. However, when antibodies to basic fibroblast growth factor were used the invasive activity induced by the AIDS-KS-cell-conditioned media was only marginally inhibited, suggesting that the large quantities of basic fibroblast growth factor-like material released by the AIDS-KS cells are not the main mediators of this effect. Specific inhibitors of laminin and collagenase IV action, which represent critical determinants of basement membrane invasion, blocked the invasiveness of the AIDS-KS cell-activated endothelial cells in these assays. These data indicate that KS cells appear to be of smooth muscle origin but secrete a potent inducer of endothelial cell chemotaxis and invasiveness which could be responsible for angiogenesis and the resulting highly vascularized lesions. These assays appear to be a model to study the invasive spread and angiogenic capacity of human AIDS-related KS and should prove useful in the identification of molecular mediators and potential inhibitors of neoplastic neovascularization.

Acquired Immunodeficiency Syndrome↗

Posttranslational gastrin processing depends on tumor morphology.

Extracellular matrices have recently been demonstrated to alter cell morphology in culture. Altered cell morphology has been associated with changes in gene transcription and translation, but it is not known whether it also affects posttranslational processing. Using tyrosine-O-sulfation as a marker of processing, we studied the effects of various substrates on biologically active gastrin (IRG) production and sulfation in gastrin-containing tumor cells (GT cells). Dispersed GT cells were plated onto different substrates and then incubated. Culture media from days 4, 7, and 28 were assayed with specific antibodies that recognize total IRG and nonsulfated IRG. Cells cultured on plastic and dried films of laminin, collagen, and Matrigel (Collaborative Research Inc., Lexington, Mass.) flattened and formed monolayers of GT cells. Cells cultured on a porous membrane and hydrated gels of collagen and Matrigel did not flatten but formed spheroids of GT cells. The monolayer cultures showed an increase in sulfation with time but a decrease in IRG production. The spheroid cultures maintained a constant level of sulfation over time and, with the exception of Matrigel (gel), also showed a decrease in IRG production. These results indicate that the level of sulfation was unchanged from that of the original tumor when cells were grown in spheroids but increased when cultured as monolayers. It appears that alteration of the cellular milieu alters colony morphology, which in turn alters gastrin processing.

Cell Survival↗

The role of cell adhesion and migration in the in vitro invasiveness of mouse adrenal carcinoma cells.

Using the Matrigel invasion assay, we have examined the role of cell adhesion and migration in the invasiveness of two cell lines, DM and HSR, derived from the Y1 mouse adrenocortical tumor. The DM cells were metastatic and more invasive (10-fold) than the nonmetastatic HSR cells. The difference in invasiveness could not be ascribed to different levels of secreted type IV collagenolytic activity since HSR cells secreted higher levels of activity. Cells from the metastatic DM line showed greater motility to both laminin and fibronectin when compared to the HSR line. Furthermore, both Matrigel and laminin promoted the attachment and spreading of DM cells but they had little effect on the adhesion of the HSR cells. Electron microscopic examination revealed an increased ruffling of the cell membrane in the metastatic DM line. These studies suggest a role for cell adhesion and migration on the invasion of Matrigel by malignant tumor cells.

Adrenal Gland Neoplasms↗

Induction of cytochrome P-450 and 5-aminolevulinate synthase activities in cultured rat hepatocytes.

Cytochromes P-450IIB1 and P-450IIB2 were recently shown to be inducible in rat hepatocyte cultures maintained on a reconstituted extracellular tumor matrix (Matrigel) as indicated by increases in P-450IIB1 and -IIB2 mRNAs and immunoreactive proteins (J. Cell. Physiol., 134: 309-323, 1988). Here we show that treatment of cultured rat hepatocytes with phenobarbital and other compounds known to induce P-450IIB1/2 in vivo increased spectral cytochrome P-450, immunoreactive proteins, and benzyloxy- and pentoxy-resorufin dealkylases, activities known to be specific for cytochrome P-450IIB1/2. These increases were observed when cells were cultured on either Matrigel or collagen matrix in Williams E medium. Cytochrome P-450III was also increased by phenobarbital and dexamethasone on either matrix. Propoxycoumarin depropylase activity, which has been proposed as a specific activity catalyzed by cytochrome P-450III, was increased 3-4-fold more by treatment with 3-methylcholanthrene than by phenobarbital or dexamethasone. The activity catalyzed by P-450III could be distinguished from that catalyzed by other P-450 forms using the specific inhibitor triacetyloleandomycin. Benzoyloxyresorufin dealkylase was also increased in these cells by treatment with 2,4,5,2',4',5'-hexachlorobiphenyl, glutethimide, or mephenytoin. Treatment with phenobarbital or 2-allyl-2-isopropylacetamide slightly induced 5-aminolevulinate synthase activity. 5-Aminolevulinate synthase activity was slightly increased in cells treated with phenobarbital or 2-allyl-2-isopropylacetamide. Succinyl acetone also induced 5-aminolevulinate synthase activity and, in combination with either of the other two drugs, synergistically increased the enzyme activity regardless of whether cells were cultured on collagen or Matrigel. These results indicate that with simple and economical enzyme assays for holocytochrome P-450 and 5-aminolevulinate synthase, the rat hepatocyte culture system can be used for studies of the interrelationships between phenobarbital induction of cytochrome P-450 and heme metabolism.

5-Aminolevulinate Synthetase↗

Blocking of collagenase secretion by estramustine during in vitro tumor cell invasion.

The effects of the antitumorigenic drug estramustine on tumor cell membrane penetration (invasion) were investigated in vitro by utilizing a synthetic basement membrane system (a modified Boyden chamber). Tumor cells were plated on a "partition barrier," consisting of a porous filter (8-micron pores) which was coated with a reconstituted basement membrane matrix (Matrigel), and induced to migrate across the barrier with conditioned medium obtained from 9DU 145 human prostatic tumor cells (passage 9). Quantitative radiolabeling studies demonstrated that specially isolated lines (isolated by several passages through the Matrigel) of DU 145 cells, A2058 melanoma, and B16-F10 melanoma cells were highly invasive such that 15 to 20% migrated across a 1-mm-thick Matrigel layer within 5 h at 37 degrees C. NIH-3T3 cells, mouse fibroblasts, and 20DU 145 cells (passage 20) exhibited little or no membrane invasive behavior. Micromolar concentrations of estramustine (30 to 120 microM) inhibited invasion by the invasive cell lines in a dosage-dependent fashion. Quantitative enzymatic assays and radioimmune assays demonstrated that estramustine inhibited membrane invasion by blocking type IV collagenase secretion. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blots confirmed that 30 to 60 microM estramustine blocked secretion of a Mr 105,000 collagenase protein. Indirect studies showed that a collagenase antibody raised against the Mr 105,000 protein and inhibitors of proteinase activity, including a metalloproteinase inhibitor, and 1,10-phenanthroline, blocked invasion. Because the antibodies inhibited type IV collagenase digestion of 3H-mouse type IV collagen, and invasion simultaneously, it is proposed that collagenolytic activity is involved in invasion. These data demonstrate that estramustine blocks proteinase secretion, and suggest that estramustine may be a useful therapeutic drug for the prevention of metastasis.

Cell Division↗

Isolation of rat aortic endothelial cells by primary explant techniques and their phenotypic modulation by defined substrata.

An efficient and reliable procedure for the isolation and culture of endothelium from large vessels of small animals (e.g., rat) is described, which takes advantage of endothelial cell-extracellular matrix interactions to promote the outgrowth of cells from tissue explants. The procedure may also permit the isolation by nonenzymatic means, of endothelial cells from other vessels and tissues. Rings and opened segments of aortic tissue were placed on a variety of substrates including: untreated tissue culture plastic; films of fibronectin, laminin, type I collagen, and gelatin; gels of type I collagen (Vitrogen, Collagen Corporation, Palo Alto, California), of basement membrane components derived from the EHS sarcoma (Matrigel, Collaborative Research Inc., Lexington, Massachusetts), and of agar and agarose. The medium used was OPTI-MEM or RPMI 1640 (Gibco Laboratories, Grand Island, New York) with 3% or 20% fetal calf serum, and 50 micrograms/ml endothelial cell growth supplement. Only explants on Vitrogen and on Matrigel produced a significant and consistent outgrowth of cells and this occurred shortly after the initiation of explants. Virtually no outgrowth occurred from explants on the other substrata, even after 10 days in culture. On Vitrogen gels, the cells emerged from the explants as single stellate and bipolar cells, whereas those on Matrigel grew as chains and sheets from the edges of the explant. Cells were passaged from both types of gels onto plastic or glass surfaces. The passaged cells isolated from both gel matrices exhibited specific endothelial cell characteristics including a "cobbled" morphology at confluence, positive staining for von Willebrand factor, and uptake of Di-I-Ac-low density lipoprotein. Because rat and other small animal aortic endothelial cells are resistant to isolation by enzymatic treatment, this technique provides a simple means to obtain large numbers of this cell type. Further, the method permits study of endothelial cell functions in vitro, and the roles which the extracellular matrix may play in these processes.

Animals↗

Perturbations in the fibrinolytic pathway abolish cyst formation but not capillary-like organization of cultured murine endothelial cells.

Fibrinolytic activity and its relation to morphogenesis was investigated in several transformed murine endothelial cell lines and primary cultures of endothelial cells. Two in vitro systems, fibrin gels and Matrigel (Collaborative Research, Bedford, MA), were used. Fibrin gels model a fibrin-rich extracellular matrix that frequently supports neovascularization in vivo, and Matrigel models the basement membrane surrounding quiescent endothelial cells in vivo. The transformed endothelial cell lines have higher levels of plasminogen activator (PA) mRNA than primary cultures of endothelial cells, and an increased PA-mediated proteolytic activity was correlated with formation of cysts in fibrin gels. Addition of neutralizing anti-urokinase antibodies, plasminogen depletion, or addition of a plasmin inhibitor prevented cyst formation. Addition of plasminogen restored the ability to form cysts in the plasminogen-depleted system. Normal endothelial cells organized into capillary-like structures in fibrin gels regardless of manipulations affecting the fibrinolytic pathway. In Matrigel, both transformed and primary cultures of endothelial cells rapidly formed a capillary-like network that was not affected by plasminogen depletion or addition of plasmin inhibitors. Thus, elements of the fibrinolytic pathway necessary for cyst formation are not critical in capillary-like structure formation on a reconstituted basement membrane. These results suggest that plasmin is essential for hemangioma formation but is not critical to the organizational behavior of normal endothelial cells.

Animals↗

[Antitumor effect of intratumoral administration of BRM: inhibition of tumor cell invasion in vitro].

The effect of intratumoral administration of BRMs in Meth-A solid tumor has been analyzed in BALB/c mice. The effect of BRMs on in vitro invasion by murine RL male-1 leukemia cells was studied using Biocoat Matrigel Invasion Chamber (Becton Dickinson Labware). We determined the ability of tumor cells to penetrate matrigel-coated filters in the presence or absence of BRM. PSK or OK-432 inhibited tumor cell invasion of matrigel-coated filters in a dose-dependent manner. PSK, OK-432 and Cepharanthin inhibited invasion of murine Colon 26 carcinoma cells and human A 375. S2 melanoma cells. On the other hand, polysaccharide preparations without protein, Lentinan or Sonifilan inhibited neither tumor growth nor tumor cell invasion.

Animals↗

Effects of extracellular matrices on tube formation of cultured rat hepatic sinusoidal endothelial cells.

To determine the effects of extracellular matrices on the function and morphology of hepatic sinusoidal endothelial cells, isolated rat hepatic sinusoidal endothelial cells were cultured in three-dimensional fashion on collagen gel containing various extracellular matrix components. Cells cultured on type I collagen gel with or without type IV collagen formed a cobblestone appearance on the surface of the gel. Cells cultured on laminin-containing type I collagen gel invaded the gel and exhibited three-dimensional tube formation with a decreased number of characteristic endothelial pores. Morphometrically, there was a significant relationship between the length of the tube formed and the concentration of laminin in the type I collagen gel. Cells cultured on Matrigel, which contains high concentrations of laminin, type IV collagen, fibroblast growth factor, tissue plasminogen activator, and other growth factors, formed a great number of tubes into a network on the surface of the gel, as is observed in the situ hepatic sinusoidal endothelial cells. Ultrastructurally, tube-forming endothelial cells cultured on Matrigel had many endothelial pores on the cell surface, with tubes (approximately 10 microns in diameter) formed by two or three hepatic sinusoidal endothelial cells. These results indicated that extracellular matrix components, especially laminin, induced the formation of tubes in cultured rat hepatic sinusoidal endothelial cells. Tube-forming sinusoidal endothelial cells cultured on Matrigel could provide more advantages than the two-dimensional culture model for investigating the function and morphology of these cells in vitro.

Animals↗

[The factors involved in invasive ability of endometrial carcinoma cells].

The in vitro invasive ability, the expression of cell adhesion molecule E-cadherin, activity of matrix metalloproteinase (MMP) and K-ras point mutation were investigated in eight human endometrial carcinoma cell lines. 1) In vitro invasive abilities of endometrial carcinoma cell lines depend on the degree of cell differentiation and the origin of cell lines. A poorly-differentiated carcinoma cell line (NUE-1) and a cell line derived from metastatic lymph node (SNG-M) were more invasive than moderately-(HEC-1A, HEC-1BE) and well-differentiated (HEC-6, Ishikawa) cell lines. 2) Immunohistochemically, less or non-invasive cell lines expressed E-cadherin strongly, whereas a highly invasive cell line (NUE-1) expressed E-cadherin weakly. 3) When cultured on Matrigel-coated dishes, the tumor cells derived from moderately- and well-differentiated carcinoma aggregated with each other and did not invade Matrigel in the invasion assay. The aggregated cells expressed E-cadherin more strongly when cultured on Matrigel. 4) 72-kD gelatinase (MMP-2) was secreted in serum-free conditioned medium of all cell lines. In an invasive cell line (NUE-1,SNG-M), the activity of MMP-2 was stronger than in other cell lines. And the activity of 92-kDa gelatinase (MMP-9) was detected in most invasive cell line (NUE-1). 5) Point mutation of K-ras codon 12 was detected in four of eight (50%) cell lines by the PCR-RFLP method. The changes in the DNA sequence were identified, but K-ras point mutation was not correlated with in vitro invasiveness of the tumor cells.

Cadherins↗