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Isolation, cell culture, and characterization of oviduct epithelial cells of the cow.

This report describes an easy method of isolation and cell culture of the epithelial cells of cow oviduct. Incubation of cow oviduct with 0.1 mg/ml collagenase in the lumen for 90 minutes helped to dislodge large numbers of ciliated and secretory epithelial cells. The isolated cells, when seeded on plastic, proliferated very quickly and became confluent in 8-10 days in 35 mm Petri dishes. The isolated ciliated cells which attached to the plastic dish lost their cilia after 4-5 days in culture. The cultured epithelial cells were keretin positive. The isolated bovine oviduct epithelial cells, when cultured on plastic precoated with 10 mg/ml matrigel, organized themselves into hollow tubes or spheres with microvilli directed towards the lumen. The epithelial cells seeded on 2 mg/ml matrigel became subconfluent in 15-20 days after seeding. The histoarchitecture of the secretory cells growing in vitro on matrigel resembled that of intact oviduct secretory epithelial cells. Occasional ciliated cells containing large number of mitochondria were observed in the monolayer cultured on 2 mg/ml matrigel substratum but possessed few cilia. The oviduct epithelial cells cultured on 2 mg/ml matrigel incorporated 35S-methionine linearly into protein up to 8 hours in the presence of estradiol or progesterone. The fluorograph of the newly synthesized proteins indicated the presence of an additional 60 kd protein in the cell extract of epithelial cells incubated with estradiol.

Animals↗

Growth and differentiation of the cultured secretory cells of the cow oviduct on reconstituted basement membrane.

Isolated bovine oviduct epithelial cells were cultured on plastic precoated with matrigel. The epithelial cells seeded on 10 mg/ml matrigel often organized themselves into hollow tubes or spheres with microvilli directed towards the lumen. This is the first report of describing the spontaneous tube formation of oviduct epithelial cells in vitro. The epithelial cells growing on this substratum became fully differentiated with the formation of junctional complexes and the production of secretory vesicles which migrated to apical plasmalemma. Epithelial cells seeded on 2 mg/ml matrigel (dry film) formed a subconfluent monolayer in 15-20 days after seeding. The histoarchitecture of the secretory cells growing on the matrigel dry film closely resembled that of intact epithelial cells. Occasional ciliated cells containing large numbers of mitochondria were observed in cell colonies growing on 2 mg/ml matrigel but they possessed very few intact cilia. The monolayer linearly incorporated 35S-methionine into proteins up to 8 hr in presence of estradiol or progesterone. The fluorography of the newly synthesized proteins indicated that the cell extracts of estradiol-stimulated cells contained an additional protein of approximate molecular weight of 60 kd as compared to the extracts of cells incubated without steroids or incubated with progesterone.

Animals↗

Ornithine decarboxylase is directly involved in mouse mammary carcinoma cell invasion in vitro.

To elucidate the role of ornithine decarboxylase (ODC) in cancer cell invasion, we have compared the invasiveness of mouse mammary carcinoma, FM3A and its variant cell line, EXOD, which overproduces ODC. We have found that EXOD cells showed about 5.6-fold more invasiveness through a reconstituted basement membrane (Matrigel) compared to FM3A cells. To elucidate the underlying mechanism of increased invasiveness of EXOD cells, we analyzed gelatinase activity in conditioned media derived from FM3A and EXOD cells. EXOD cells secreted approximately 3-fold 72kDa gelatinase compared to FM3A cells. Cell attachment ability to Matrigel was also studied. Although FM3a and EXOD cells showed increased attachment to Matrigel in a dose-dependent manner, EXOD cells showed higher cell attachment ability compared to FM3A cells. Anti-72kDa gelatinase neutralizing antibody suppressed EXOD cell invasion through Matrigel. Further, antisense oligonucleotides of ODC suppressed EXOD cell invasion through Matrigel. Although the causal relationship among ODC expression, gelatinase secretion and cell attachment ability remains to be elucidated, the results suggest that both overproduction of ODC and 72kDa gelatinase secretion are directly involved in increased invasiveness of EXOD cells.

Animals↗

Extracellular matrix, growth factors, genetics: their influence on cell proliferation and myotube formation in primary cultures of adult mouse skeletal muscle.

Cell proliferation and myotube formation in response to growth factors on various extracellular matrices (ECM) were investigated in primary skeletal muscle cultures from adult SJL/J and BALB/c mice. There was no difference between the rates of proliferation from primary cultures of SJL/J and Balb/c mice measured at 48 h in response to a range of concentrations of PDGF-AA, -AB, -BB, TGF beta 1, or LIF (added at 24 h). SJL/J primary cultures were more responsive to bFGF (which was the most potent mitogen) than were BALB/c cultures. Comparison of dose response curves to bFGF and TGF beta 1 grown on gelatin or Matrigel showed that the nature of the ECM did not have a significant affect. More myotubes formed at 4 days in SJL/J than in parallel BALB/c cultures on gelatin or Matrigel (P < 0.05). On gelatin more myotubes with 4 or more nuclei were formed in cultures from SJL/J than BALB/c muscles (P < 0.05); however, on Matrigel these myotubes occurred with similar frequency. Myotube formation examined in BALB/c muscle cultures grown on collagen i.v., entactin-free laminin, and fibronectin showed that none of these ECM components alone supported large myotube formation (4 or more nuclei) as well as did Matrigel, although fibronectin was as effective as Matrigel with respect to the total number of myotubes formed. Parallel experiments carried out using the myogenic H-2Kb(27) cell line showed similar effects with the exception of laminin which enhanced large myotube formation and desmin expression in the H-2Kb(27) but not in the primary muscle cultures. The greater sensitivity in mitogenic response to bFGF and the more extensive myotube formation seen in SJL/J compared with BALB/c cultures in vitro reflects the superior capacity for muscle regeneration of SJL/J mice in vivo.

Analysis of Variance↗

In vitro validation of duct differentiation in developing embryonic mouse pancreas.

BACKGROUND: Early embryonic pancreatic epithelia have the capacity for either endocrine or exocrine lineage commitment. Recent studies demonstrated the pluripotential nature of these undifferentiated cells. Isolated pancreatic epithelia grown under the renal capsule formed primarily islets. However, when these same epithelia were grown in a basement-membrane-rich gel (Matrigel) they formed mostly ducts. Currently, there is no model for in vitro pancreatic duct formation and therefore, the mechanism of duct morphogenesis has never been described. The purpose of this study was to provide such a model by characterizing the expression of two duct markers, carbonic anhydrase II (CAII) and the cystic fibrosis transmembrane conductance regulator (CFTR), in isolated undifferentiated pancreatic epithelia grown in vitro. MATERIALS AND METHODS: We microdissected embryonic pancreases at Embryonic Days (E)9.5-11.5 and performed RT-PCR for CAII and CFTR on E9.5 whole pancreases, E10. 5 and E11.5 epithelia, as well as E11.5 epithelia grown for 7 days in Matrigel. Next we performed in situ hybridization for CAII and CFTR and immunohistochemistry for CAII on E11.5 epithelia grown for 7 days in Matrigel. RESULTS: Early, undifferentiated embryonic pancreatic epithelium does not express CAII and CFTR by RT-PCR. When E11.5 epithelia were grown for 7 days in Matrigel, however, gene expression for both markers is upregulated as ducts form. Furthermore, CAII was seen by IHC and both CAII and CFTR were seen by in situ hybridization in the ducts after 7 days in Matrigel. CONCLUSIONS: These data validate our in vitro system as a model for studying the mechanism of normal pancreatic duct differentiation and may potentially help us to understand the faulty mechanism involved in pancreatic ductal carcinogenesis.

Animals↗

Basement membrane and the SIKVAV laminin-derived peptide promote tumor growth and metastases.

Laminin, the major glycoprotein component of basement membrane, promotes the malignant phenotype. Cells which are adherent to laminin are more malignant than the non-adherent cells and in certain tumor cells, the number of laminin receptors is positively correlated with malignancy. Laminin also increases collagenase IV activity, an enzyme demonstrated to be critical for tumor spread. A site on laminin, containing the amino acid sequence SIKVAV, has been identified which when injected intravenously with B16F10 melanoma cells, causes an increase in the number of colonies on the surface of the lungs. This peptide does not affect tumor cell arrest in the vasculature or the immune system. It does promote angiogenesis in various in vitro and in vivo models, thereby facilitating tumor cell survival. When a complex mixture of laminin-enriched basement membrane components (Matrigel) is coinjected with tumor cells subcutaneously, tumor incidence and growth increases. Various tumor cell lines and primary isolates, which previously could not form tumors in mice, can be induced to grow rapidly in the presence of Matrigel. Slowly growing tumors or arrested tumors can also be induced to grow more quickly with additional injections of Matrigel. When an SIKVAV-containing synthetic peptide is coinjected with B16F10 tumor cells and Matrigel subcutaneously in mice, larger tumors are formed than that observed with either Matrigel or cells alone. Such studies define the role of laminin in tumor growth and spread and generate new models for studying therapeutic agents. Of particular interest is the ability to grow primary isolates which generally do not grow in mice.

Amino Acid Sequence↗

Attachment, invasion, chemotaxis, and proteinase expression of B16-BL6 melanoma cells exhibiting a low metastatic phenotype after exposure to dietary restriction of tyrosine and phenylalanine.

We previously reported that low levels of tyrosine (Tyr) and phenylalanine (Phe) alter the metastatic phenotype of B16-BL6 (BL6) murine melanoma and select for tumor cell populations with decreased lung colonizing ability. To more specifically characterize the effects of Tyr and Phe restriction on the malignant phenotype of BL6, we investigated in vitro attachment, invasion, proteinase expression, and chemotaxis of high and low metastatic BL6 variants. High metastatic variant cells were isolated from subcutaneous tumors of mice fed a nutritionally complete diet (ND cells) and low metastatic variant cells were isolated from mice fed a diet restricted in Tyr and Phe (LTP cells). Results indicate that attachment to reconstituted basement membrane (Matrigel) was significantly reduced in LTP cells as compared to ND cells. Attachment to collagen IV, laminin, and fibronectin were similar between the two variants. Invasion through Matrigel and growth factor-reduced Matrigel were significantly decreased in LTP cells as compared to ND cells. Zymography revealed the presence of M(r) 92,000 and M(r) 72,000 progelatinases, tissue plasminogen activator, and urokinase plasminogen activator in the conditioned medium of both variants; however, there were no differences in activity of these secreted proteinases between the two variants. Growth of the variants on growth factor-reduced Matrigel similarly induced expression of the M(r) 92,000 progelatinase. The variants exhibited similar chemotactic responses toward laminin. However, the chemotactic response toward fibronectin by LTP cells was significantly increased. MFR5, a monoclonal antibody which selectively blocks function of the alpha 5 chain of the alpha 5 beta 1 integrin, VLA-5, decreased the chemotactic response toward fibronectin of ND cells by 37%; the chemotactic response by LTP cells was reduced by 49%. This effect was specific for fibronectin-mediated chemotaxis since the chemotaxis toward laminin and invasion through Matrigel were not altered by the presence of MFR5. The surface expression of VLA-5 was significantly increased in LTP cells as compared to ND cells by flow cytometric analysis. These observations suggest that limitation of Tyr and Phe either directly modifies BL6 or selects for subpopulations with altered in vitro invasion, chemotaxis, and integrin expression.

Animals↗

Secretion of matrix metalloproteinase-2 (72 kD gelatinase/type IV collagenase = gelatinase A) by malignant human glioma cell lines: implications for the growth and cellular invasion of the extracellular matrix.

Human glioma cells (T98G and A172 cell lines) were cultured on various extracellular matrix (ECM) components including type I, IV and V collagens, fibronectin, laminin, and reconstituted basement membrane (Matrigel), and the role of matrix metalloproteinases (MMPs) in their growth and invasion was examined. T98G glioma cells grew well on these ECM components and invaded the reconstituted basement membrane. In contrast, A172 glioma cells showed growth inhibition on collagen types IV and V and Matrigel without invasion of the Matrigel. Gelatin zymography and enzyme immunoassays demonstrated that T98G glioma cells, but not A172 cells, secrete a large amount of matrix metalloproteinase-2 (MMP-2, 72 kD gelatinase/type IV collagenase = gelatinase A), and this was confirmed by immunoblotting and immunohistochemistry. Of the two different tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2), T98G cells produced only TIMP-1 during culture on Matrigel, whereas A172 cells secreted both. Although both human recombinant TIMP-1 and TIMP-2 stimulated T98G cell growth slightly on Matrigel, the in vitro invasiveness was significantly reduced by only recombinant TIMP-2. These results suggest that MMP-2 plays an important role in the ECM invasion of T98G human glioma cells in vitro.

Brain Neoplasms↗

Extracellular matrix permits the expression of von Willebrand's factor, uptake of di-I-acetylated low density lipoprotein and secretion of prostacyclin in cultures of endothelial cells from rat brain microvessels.

Microvascular endothelial cells from the adult rat brain were cultured on Matrigel and found to express many differentiated properties including secretion of prostacyclin (PGI2) and von Willebrand's factor (vWF). Brain microvascular endothelial cells (BMECs) were purified by dextran and percoll gradients after enzymatic treatment and cultured under various conditions. BMECs that were plated on Matrigel stained positively for factor VIII-related antigen and incorporated Di-I-acetylated low density lipoprotein, whereas BMEC plated on fibronectin, gelatin, or uncoated dishes did not express any of the above properties which are characteristic of endothelial cells. vWF was measured by a sensitive ELISA in the culture media of BMECs plated on different types of matrices. Specificity of the anti-human vWF antibodies for the rat vWF was verified by immunoabsorption on a solid phase, sodium dodecyl sulfate, and Western blot analysis. BMECs also secreted vWF into the culture media only when the cells were plated on Matrigel, and this secretion was augmented after a 6 h incubation with an interleukin-1 tumor necrosis factor-alpha mixture, but not by lipopolysaccharide. From different matrices tested, only Matrigel permitted the secretion of PGI2 by BMECs. Cells also proved to be sensitive to mechanical stimulation and became refractory to secretagogue if the mechanical stimulation was serially repeated. Under the best conditions, stimulation of the cells with bradykinin (1 microM) substantially increased PGI2 secretion. These data indicate that growth of BMECs on Matrigel in vitro permits the expression of classical endothelial cell markers in a manner similar to the behavior of these cells in situ.

Acetylation↗

Enhanced migration of the acute promyelocytic leukemia cell line NB4 under in vitro conditions during short-term all-trans-retinoic acid treatment.

All-trans-retinoic acid (RA) is a potent differentiating agent that is very effective in the treatment of patients with acute promyelocytic leukemia (APL). Since clinical response can be accompanied by extramedullary manifestations, we have investigated the influence of RA on cell adhesion to and migration through reconstituted basement membranes (Matrigel) in the APL cell line NB4. No apparent cellular differentiation was observed during a 24-h incubation with 1 microM RA, as indicated by the nitroblue tetrazolium reduction test. However, exposure to RA significantly enhanced NB4 cell adhesion to Matrigel and consecutive migration through Matrigel barriers in a dose-dependent manner. Several integrin molecules potentially involved in this process, i.e., CD29, CD18, CD11a, CD11b and CD11c, were therefore studied by fluorescence-activated cell sorting analysis. The expression of the beta subunit of the beta2 integrins (CD18), but not that of beta1 integrins (CD29), was increased during 24-h RA treatment. Among the beta2 integrins, the expression of LFA-1 (CD11a) and of Mac-1 (CD11b), but not of p150,95 (CD11c), was induced by RA. When monoclonal antibodies that specifically block the interaction of these integrins with their ligands were used, we observed that CD29 is only involved in adhesion and CD11b only in migration, whereas CD11a participates in both processes. NB4 cells constitutively secreted the matrix metalloproteinases MMP-9 and MMP-2, which are known to promote cellular invasion processes by degradation of the extracellular matrix. RA treatment had no influence on the quantity of secreted MMP-9 or MMP-2 in these cells as determined by zymography. Addition of Batimastat (BB-94), a synthetic inhibitor of matrix metalloproteinases, blocked RA-induced cell migration without affecting cellular adhesion to Matrigel. These findings indicate that adhesion molecules as well as matrix metalloproteinases are involved in RA-stimulated migration of NB4 cells through Matrigel, possibly providing some explanation of tissue infiltration by leukemic cells as observed during treatment of APL patients with RA.

Antibodies, Monoclonal↗

Culture matrix configuration and composition in the maintenance of hepatocyte polarity and function.

Several extracellular matrix (ECM) configurations involving type I collagen and Matrigel were examined for their ability to support differentiated function and polarity of cultured adult rat hepatocytes. Collagen sandwich- and Matrigel-based cultures yielded superior and comparable albumin secretion for at least 2 weeks. In collagen sandwich, hepatocytes were polygonal, and formed multicellular arrays. Collagen sandwich was also found to promote in vivo-like polarization of F-actin, cell adhesion molecules (E-cadherin), and lateral (Na+, K(+)-ATPase, glucose transporter) and apical (dipeptidyl peptidase, aminopeptidase) membrane polarity markers, but not the expression of the gap junction protein connexin 32 and the epidermal growth factor (EGF) receptor. In contrast, hepatocytes cultured in or on Matrigel were more rounded and formed aggregates. Matrigel-based cultures also elicited detectable levels of connexin and EGF receptor and an altered distribution of F-actin, E-cadherin, and apical and lateral membrane proteins. Composite sandwich configurations containing collagen I and Matrigel restored markers lacking in the collagen sandwich, and showed a variable morphology and membrane polarity. Hepatocyte polarity could thus be manipulated by the overall ECM composition. Furthermore, in composite sandwich cultures, these manipulations can be effected largely independent of changes in hepatocyte morphology and albumin secretion.

Actins↗

Stability of angiogenic agents, ginsenoside Rg1 and Re, isolated from Panax ginseng: in vitro and in vivo studies.

The study was designed to investigate the stability of ginsenoside Rg(1) (Rg(1)) and Re (Re), two natural herbal compounds isolated from Panax ginseng, based on their activity to promote angiogenesis in vitro and in vivo. After being treated at different temperatures, pHs, and solvent species for distinct durations, the remaining activities of Rg(1) and Re on human umbilical vein endothelial cell (HUVEC) proliferation, migration, and tube formation were examined in vitro. Additionally, the remaining activity of each treated test agent, mixed in a growth factor-reduced Matrigel, in stimulating angiogenesis was evaluated subcutaneously in a mouse model. Basic fibroblast growth factor (bFGF) was used as a control. It was found in vitro that HUVEC proliferation, migration in a Transwell plate, and tube formation on Matrigel were all significantly enhanced in the presence of bFGF, Rg(1), or Re. However, after being treated at different temperatures, pHs, or solvent species, the remaining activity of bFGF on HUVEC behaviors reduced significantly. This observation was more significant with increasing the duration of treatment. In contrast, the activities of Rg(1) and Re remained unchanged throughout the entire course of the study. The in vivo results observed on day 7 after implantation showed that the blank control (Matrigel alone) was slightly vascularized. In contrast, the density of neo-vessels in the Matrigel plug mixed with bFGF, Rg(1), or Re was significantly enhanced. However, after being treated, the density of neo-vessels was significantly reduced in the Matrigel plug mixed with bFGF, while those of Rg(1) and Re remained unchanged. The aforementioned results suggested that Rg(1) and Re could be a novel group of nonpeptide angiogenic agents with a superior stability and may be used for the management of tissue regeneration.

Angiogenesis Inducing Agents↗

Colorectal cancer cell adhesion attenuates Ad-E2F-1 mediated apoptosis.

BACKGROUND: The complex interplay of cell adhesion molecules, intracellular signaling, and tumor growth behavior have important implications for the failure of most conventional cancer therapies. Cell adhesion to the basement membrane has been shown to promote tumor cell survival. We hypothesize that the presence of matrix substrate contributes to chemoresistance through signaling via cell adhesion molecule. MATERIALS AND METHODS: RKO colorectal cancer cells express integrin beta1 to adhere to substrate. We measured apoptosis of the cells after infection with adenovirus vector containing the transgene E2F-1 (Ad-E2F-1), a potent tumor suppressor gene, and Ad-LacZ (as control), both under the control of the cytomegalovirus promoter. Cells were plated on Matrigel, an extracellular substrate similar to basement membrane and compared to tissue culture plastic. Apoptosis was assessed by flow cytometry-based TUNEL assay and cell proliferation was assessed by WST-1 assay. E2F-1 expression was confirmed by Western blot analysis. A function-blocking anti-beta1 integrin antibody was used to assess the contribution of beta1 on cell survival. RESULTS: At 120 h postinfection of RKO cells with 50 multiplicity of infection, cells plated on plastic underwent marked apoptosis in response to Ad-E2F-1 compared with Ad-LacZ control-treated cells (53% vs 1% apoptosis, respectively). However, when cells were plated on Matrigel, the same dose of E2F-1 was ineffective at inducing apoptosis (3% vs 1% apoptosis, comparing Ad-E2F-1 with Ad-LacZ control). The cell proliferation assay showed >3-fold cell survival in E2F-1-infected cells on Matrigel vs plastic (P < 0.004). By Western blot analysis, attenuation of apoptosis may be a result of reduction in transduction efficiency on Matrigel and function-blocking anti-beta1 integrin antibody does not abolish the decrease in apoptosis afforded by Matrigel. CONCLUSIONS: These data suggest that escape from adenoviral E2F-1-mediated apoptosis, at least in part, is related to reduction of intracellular E2F-1 expression. Interactions involving cellular adhesion via beta1 integrin to matrix proteins does not seem to contribute toward gene therapy resistance. Further studies will investigate other specific receptor-ligand interactions after gene and/or chemotherapy.

Adenoviridae↗

Establishment and characterization of two new Kaposi's sarcoma cell cultures from an AIDS and a non-AIDS patient.

We have established and characterized two new Kaposi's sarcoma (KS) cell lines derived from skin biopsies: AIDS-KSISTIV (from an AIDS-associated KS) and KSISTVIII (from a sporadic KS). AIDS-KSISTIV and KSISTVIII are composed mostly of spindle-shaped cells. They show similar patterns of immunohistochemical staining and are positive for smooth muscle (smooth muscle alpha-actin) and fibroblastoid (TE7) markers. Neither of these lines express the endothelial marker von Willebrand factor VIII. These immunohistochemical patterns are similar to numerous other KS lines that we and others have established. When seeded on a reconstituted basement membrane ("Matrigel"), AIDS-KSISTIV and KSISTVIII cells form branching colonies and invade into the Matrigel, as do other KS cultures that we have previously examined. This behaviour on Matrigel is similar to that of malignant sarcoma cells of different origin. The expression of vimentin and the morphology of the invasive colonies on Matrigel suggest that KS-derived cells are poorly differentiated mesenchymal cells. KS lesions are characterized by a conspicuous neovascularization, which appears to be derived from host cell recruitment. We tested the capability of the KS-cell supernatants to induce an angiogenic response in vitro. The new lines are able to stimulate human endothelial cell chemotaxis and invasion through Matrigel-coated filters. No differences in angiogenic potential in vitro were observed between the AIDS and the non-AIDS case, as we previously noted for other established cultures. Our new lines have the properties of true KS cells and confirm that KS spindle cells from HIV-positive or -negative patients have identical phenotypic and behavioural characteristics in vitro.

Acquired Immunodeficiency Syndrome↗

Adenovirus-mediated wild-type p53 overexpression inhibits endothelial cell differentiation in vitro and angiogenesis in vivo.

Gene therapy with the tumor suppressor gene p53 induces cancer cell apoptosis in vitro and in vivo and inhibits tumor growth in nude mice. We hypothesized that, in addition to cancer cell apoptosis, a replication-deficient adenovirus vector which carries the cDNA for human wild-type p53 (AdCMV.p53) may also modulate endothelial cell function and inhibit angiogenesis. Human umbilical vein endothelial cells (HUVEC) were infected at different multiplicities of infection (MOI) with either AdCMV.p53, the control vector AdCMV.null or were not infected. Western blot analysis showed p53 overexpression up to 7 days after infection with AdCMV.p53. HUVEC proliferation was either not affected (20 and 50 MOI) or inhibited to comparable levels (100 MOI; P < 0.05) in AdCMV.p53- and AdCMV.null-infected versus uninfected cells. HUVEC differentiation into capillary-like structures on reconstituted basement membrane proteins (Matrigel) was assessed 48 h after infection (100 MOI). After 18 h on Matrigel the capillary-like network formed by AdCMV.p53-infected HUVEC was less extensive than that formed by both AdCMV.null-infected and uninfected control cells (P < 0.05 versus either control). In contrast, conditioned medium from AdCMV.p53-infected HUVEC did not modulate endothelial cell differentiation on Matrigel. The effect of AdCMV.p53 on angiogenesis in vivo was assessed by injecting this vector subcutaneously in mice; 3 days later Matrigel containing basic fibroblast growth factor (bFGF) was injected at the same site. In other experiments AdCMV.p53 was injected simultaneously with an Ad vector coding for vascular endothelial growth factor (AdCMV.VEGF165) into the rat perirenal fat tissue. AdCMV.p53 significantly inhibited neovascularization induced by bFGF within the Matrigel plugs (P < 0.05) or by AdCMV.VEGF165 in the fat tissue (P < 0.05). Thus, the anti-angiogenic effect of Ad-mediated wild-type p53 overexpression may contribute to the ability of this viral vector to inhibit tumor growth.

Adenoviridae↗

An extracellular ligand increases the specific activity of the receptor-like protein tyrosine phosphatase DEP-1.

Cellular growth, differentiation and migration is regulated by protein tyrosine phosphorylation. Receptor-like protein tyrosine phosphatases are thus likely to be key regulators of vital cellular processes. The regulation of these enzymes is in general poorly understood. Ligands have been identified only for a small subset of the receptor-like protein tyrosine phosphatases and in no case has upregulation of the specific activity by extracellular ligands been demonstrated. Prompted by earlier findings of ligands for receptor-like protein tyrosine phosphatases in extracellular matrix we investigated if Matrigel, a preparation of extracellular matrix proteins, contained modulators of the specific activity of the receptor-like protein tyrosine phosphatase DEP-1. Matrigel stimulation of cells increased the specific activity of immunoprecipitated DEP-1. Also, incubation of immunoprecipitated DEP-1 with Matrigel led to an increase in DEP-1 activity, which was blocked by soluble DEP-1 extracellular domain. Finally, immunoprecipitated DeltaECD-DEP-1, a mutant form of DEP-1 lacking most of the extracellular domain, failed to respond to Matrigel stimulation. These experiments identify Matrigel as a source of DEP-1 agonist(s) and provide the first evidence for upregulation of the specific activity of receptor-like protein tyrosine phosphatases by extracellular ligands.

Animals↗

Significant role of laminin-1 in branching morphogenesis of mouse salivary epithelium cultured in basement membrane matrix.

Mouse submandibular epithelium shows branching morphogenesis in mesenchyme-free conditions when covered with a basement membrane matrix (Matrigel) in medium supplemented with epidermal growth factor. In the present study, the role of laminin-1 (LN1), a major glycoprotein of Matrigel, in this culture system was defined. When the epithelium was cultured in a LN1-nidogen gel, the epithelium showed much branching, comparable to that observed with Matrigel. By electron microscopy, only a felt-like matrix was formed on the epithelial surface in the LN1-nidogen gel cultures, while an organized basal lamina structure was formed on the epithelial surface in direct or transfilter recombination cultures with mesenchyme. Next, the epithelium covered with Matrigel was cultured in medium containing either biologically active peptides from LN1, IKVAV-including peptide (2097-2108), AG10 (2183-2194), AG32 (2370-2381) or AG73 (2719-2730) from the alpha1 chain, or YIGSR-including peptide (926-933) from the beta1 chain. Only AG73 (RKRLQVQLSIRT from the alpha1 chain carboxyl-terminal globular domain) inhibited the epithelial branching in Matrigel. These results suggest that LN1-nidogen can support the branching morphogenesis of submandibular epithelium even if LN1-nidogen is not assembled into an intact basal lamina, and that the AG73 sequence is an important site on LN1, which interacts with submandibular epithelial cells.

Amino Acid Sequence↗

De novo formation of adipose tissue by controlled release of basic fibroblast growth factor.

De novo adipogenesis at the implanted site of a basement membrane extract (Matrigel) was induced through controlled release of basic fibroblast growth factor (bFGF). bFGF was incorporated into biodegradable gelatin microspheres for its controlled release. When the mixture of Matrigel and bFGF-incorporated gelatin microspheres was implanted subcutaneously into the back of mice, a clearly visible fat pad was formed at the implanted site 6 weeks later. Histologic examination revealed that the de novo formation of adipose tissue accompanied with angiogenesis was observed in the implanted Matrigel at bFGF doses of 0.01, 0.1, and 1 microg/site, the lower and higher doses being less effective. The de novo formation induced by the bFGF-incorporated microspheres was significantly higher than that induced by free bFGF of the same dose. The mRNA of a lipogenesis marker protein, glycerophosphate dehydrogenase, was detected in the formed adipose tissues, biochemically indicating de novo adipogenesis. Free bFGF, the bFGF-incorporated gelatin microspheres, or Marigel alone and bFGF-free gelatin microspheres with or without Matrigel did not induce formation of adipose tissue. This de novo adipogenesis by mixture of Matrigel and the bFGF-incorporated gelatin microspheres will provide a new idea for tissue engineering of adipose tissue.

Adipocytes↗