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PubMed1993

Liarozole and 13-cis-retinoic acid anti-prostatic tumor activity.

Liarozole fumarate (R85,246), a novel benzimidazole derivative, reduced s.c. and bone metastasis tumor growth by the androgen-independent PC-3ML-B2 human prostatic carcinoma clone in SCID mice. The drug inhibited cell invasion of Matrigel in Boyden chamber chemotactic assays and the secretion of type IV collagenase. In vitro, liarozole failed to inhibit cell proliferation and cell attachment to various substrates (Matrigel, laminin, type IV collagen, and fibronectin). In vivo, the drug also blocked type IV collagenase production in established s.c. tumors. Liarozole has been postulated by others (R. De Coster, W. Wouters, R. Van Ginckel, D. End, et al. J. Steroid Biochem. Mol. Biol., 43: 197-201, 1992) to inhibit retinoic acid catabolism. Our data indicate that liarozole treatment can increase the tumor retinoic acid levels in vivo. Studies of retinoic acid revealed that the drug independently reduced tumor growth in vivo and inhibited cell invasion of Matrigel and the secretion of collagenase IV. Surprisingly, liarozole and retinoic acid failed to exhibit measurable synergistic activity both in vitro and in vivo. Taken together these data suggest that liarozole might inhibit retinoic acid catabolism in vivo and consequently have significant therapeutic value as an anti-prostatic tumor agent.

Animals↗
PubMed1996

Neurotrophin stimulation of human melanoma cell invasion: selected enhancement of heparanase activity and heparanase degradation of specific heparan sulfate subpopulations.

Heparanase is an endo-beta-D-glucuronidase, the enzymatic targets of which are the glycosaminoglycan chains of heparan sulfate proteoglycans. Elevated levels of heparanase are associated with the metastatic potential of melanoma cells. Treatment of murine and human melanoma cells with the prototypic neurotrophin nerve growth factor (NGF) increases the production of heparanase by melanoma cells. We reported previously that physiological concentrations of NGF increased in vitro Matrigel invasion of early-passage human brain-metastatic 70W melanoma cells but not melanoma cells metastatic to other sites or nonmetastatic melanoma cells. Here we found that treatment of 70W melanoma cells with neurotrophin NT-3 increased Matrigel invasion, whereas treatment with neurotrophins other than NGF or NT-3 did not influence invasion. Mutants of NGF that do not bind to the neurotrophin receptor p75NTR or other nonneuronal growth factors were not able to enhance the invasion of 70W melanoma cells. When 70W cells were exposed to antisense oligonucleotides directed against p75NTR mRNA, there was a reduction in NGF and NT-3 binding, and the neurotrophins failed to enhance Matrigel invasion. To study the properties of heparanase in NT-regulated malignant melanoma invasive processes, we developed a sensitive heparanase assay consisting of purified [35S]heparan sulfate subpopulations separated by agarose gel electrophoresis. Incubation of 70W cells with NGF or NT-3, but not brain-derived NT factor, NT-4/5, or mutant NGF, resulted in increased release of heparanase activity that was capable of degrading a subpopulation of heparan sulfate molecules.

Base Sequence↗
PubMedDate not supplied

Cysteine proteinase inhibitors reduce malignant melanoma cell invasion in vitro.

Proteolytic enzymes are believed to be necessary for tumor cell invasion. We have studied the effects of the cysteine proteinase inhibitor E-64 and the serine and cysteine proteinase inhibitor leupeptin, on the ability of human malignant melanoma cells (LOX) to pass through an artificial basement membrane. Transwell chambers containing filters coated with the reconstituted basement membrane, Matrigel, were used. Nontoxic concentrations of the proteinase inhibitors reduced the invasion of LOX cells through Matrigel. E-64 (250 mumol/l) by 27% and leupepetin (250 micrograms/ml) by 46%. The proteinase inhibitors did not alter the growth rate of the tumor cells, their motility through uncoated filters, or their attachment to the Matrigel coated wells. Our results indicate that cysteine proteinases are involved in the degradation of basement membranes and thus contribute to the invasion of malignant melanoma cells.

Animals↗
PubMed1996

[Mechanism of tumor cell-induced extracellular matrix degradation--inhibition of cell-surface proteolytic activity might have a therapeutic effect on tumor cell invasion and metastasis].

Tumor cells produce urokinase-type plasminogen activator (uPA) in an enzymatically inactive proenzyme form (pro-uPA). Secreted pro-uPA can immediately bind to the specific uPA receptors (uPAR) on tumor cell surface with high affinity. The uPAR specifically recognizes enzymatically inactive pro-uPA and active high molecular weight-uPA (HMW-uPA) by their growth factor-like terminal domain. uPAR is a glycoprotein of approximately 55 kDa; the affinity for uPA is high (0.2 nM) and the rate of dissociation is low. Receptor-bound uPA catalizes the formation of plasmin on the cell surface to generate the proteolytic cascade that contributes to the breakdown of basement membrane and extracellular matrix. The plasma membrane uPAR has attracted considerable attention because of its role in migration and tissue invasion by mononuclear phagocytes and malignant cells. In some cell types uPAR localizes uPA to cell-cell and cell-substratum contact sites, providing the possibility of a directional proteolysis that may be involved in cell migration and invasion. Recently it has been reported that competitive displacement of uPA from uPAR resulted in decreased proteolysis, suggesting that the cell surface is the preferred site for uPA-mediated protein degradation. Various very different approaches to interfere with the expression or reactivity of uPA or uPAR at the gene or protein level were successfully tested including antisense oligonucleotides, antibodies, inhibitors and recombinant or synthetic uPA and uPAR analogues. Recently we have reported that a highly purified urinary trypsin inhibitor (UTI) efficiently inhibits soluble and tumor cell-surface receptor-bound plasmin. UTI inhibits not only tumor cell invasion in an in vitro assay but also production of experimental and spontaneous lung metastasis in an in vivo mouse model. The anti-invasive effect is dependent on the anti-plasmin activity of UTI. UTI peptide, which inhibits plasmin activity, synthesized by an automated peptide synthesizer showed mouse 3LL cell invasion inhibitory activity. UTI and the effective peptide inhibited tumor cell invasion through Matrigel. UTI did not inhibit tumor cell proliferation or the binding of the cells to Matrigel. Also, UTI did not inhibit chemotactic migration of tumor cells to fibronectin. It is likely that UTI acts as a protease inhibitor. We attempted to synthesize conjugates between ATF and UTI. Thus, conjugating a physiological plasmin inhibitor to ATF might target it to reduce cell-associated proteolytic activity to the close environment of the uPAR-expressing tumor cell surface and subsequently may effectively inhibit tumor cell invasion and metastasis, because the cell surface uPAR might be a critical component of the metastatic machinery. A method of conjugation of the UTI domain II (HI-8), to the receptor-binding amino-terminal fragment (ATF) of uPA has been developed utilizing the heterobifunctional cross-linking reagent, N-succinimidyl-3-(2-pyridyldithio) propionate (SPDP). The conjugate retained its protease inhibiting activity and showed a binding reactivity to uPAR on the surface of tumor cells. We have shown that the conjugate exhibits plasmin inhibition to the close environment of the cell surface and subsequently inhibits the tumor cell invasion through Matrigel in an in vitro invasion assay. In order to extend our idea, we attempt to produce a novel hybrid molecule consisting of the ATF of uPA placed at the N-terminus of UTI domain II (HI-8) by protein engineering techniques. Exogenously applied ATFHI hybrid protein can immediately bind to the specific uPAR on cell surfaces with high affinity. The receptor-bound hybrid protein focuses the protease-inhibiting activity to the tumor cell surface. This is effectively a bifunctional molecule which, in addition to inhibiting trypsin and plasmin activities directly, is able toblock unoccupied uPAR, thereby preventing localization of uPA activity.

Animals↗
PubMed1996

The role of matrix contact and of cell-cell interactions in choriocarcinoma cell differentiation.

Cell differentiation is supported much better by gels of extracellular matrix than by the same matrix provided as a rigid substrate. Many cell types including normal and malignant trophoblast cells, however, form multicellular multilayered aggregates on matrix gels with increased cell-to-cell contacts as compared to regular monolayers on rigid matrix substrates. In such cultures, it remained open, so far, whether stimulated expression of differentiation markers is caused by enhanced cell-to-cell communication or is displayed only by cells in direct contact to the gel. Therefore, choriocarcinoma cells (BeWo) were grown as aggregates: (a) on gels of the basement membrane-like Matrigel, (b) on plastic coated with poly-HEMA, or (c) as aggregates (spheroids) in suspension culture. Production of the differentiation marker chorionic gonadotropin was stimulated significantly in aggregates attached to gels of Matrigel or to the poly-HEMA substrate but not in suspended spheroids. With respect to cell-cell communications, however, expression of E-cadherin mRNA was not altered in any type of aggregates, as compared to control cultures on plastic. The expression of connexin43 mRNA (not of connexin26) was increased only in suspended spheroids, while microinjection of the fluorescent dye Lucifer Yellow suggested that cell communication via gap junctions was absent from cells grown as monolayers and was not induced in any type of aggregate. When cells were grown on gels of Matrigel, the relevance of direct cellular contact to the substrate for differentiation was analyzed by immunohistochemistry. Trophoblastic differentiation markers (chorionic gonadotropin, placental lactogen, placenta-type alkaline phosphatase, and pregnancy-specific glycoprotein beta 1) as well as the proliferation marker Ki-67 were not preferentially expressed in cells that were in contact with the gel. Similar random distributions of all these markers were also observed in spheroids cultured in suspension. The distributions of several matrix molecules and of different integrins were comparable between aggregates on matrix gels and those in suspension culture. According to these data, cell-cell communication appears to play a subordinate role for cytodifferentiation in cell aggregates on matrix gels, so that substrate anchorage and physical properties of the substrate may be the decisive factors. Interestingly, however, direct contact to the substrate does not seem to be essential for the stimulation of differentiation in cells on matrix gels. The results are discussed in the context of the "tensegrity"-model for cell-matrix interactions in which proper mechanical properties of the substrate are important for the regulation of cell differentiation by allowing a balanced integrity of external and cell-internal tensile forces.

Actins↗
PubMed1996

[Experimental studies on the cell adhesion molecule E-cadherin and in vitro invasion of endometrial carcinoma cell lines].

The enhancement of the in vitro invasive ability and the morphological changes caused by anti-E-cadherin antibody HECD-1 were investigated by in vitro invasion assay and electron microscopy in three human endometrial carcinoma cell lines. The cell lines were NUE-1 (E-cadherin negative and high in vitro invasive ability), HEC-1BE and HEC-108 (E-cadherin positive and low in vitro invasive ability). In NUE-1 invasive ability was not enhanced by HECD-1, but in HEC-1BE and HEC-108 invasive ability was enhanced to 223 +/- 41.2% and 307 +/- 173% by 5 micrograms/ml HECD-1. Morphologically NUE-1 invaded the extracellular matrix (Matrigel) with a long micro villis. But in HEC-1BE and HEC-108 the villis did not invade the Matrigel, the whole cell invaded it. Together with HECD-1, HEC-1BE and HEC-108 were changed to become similar to the NUE-1 cell line with high invasive ability and the micro villis invaded the Matrigel.

Adenocarcinoma↗
PubMed1997

Angiogenesis induced in vivo by hepatocyte growth factor is mediated by platelet-activating factor synthesis from macrophages.

This study shows that the neoangiogenesis induced by hepatocyte growth factor (HGF) was associated with a local synthesis of platelet-activating factor (PAF) and was inhibited by the specific PAF receptor antagonist WEB 2170 in a murine model in which matrigel was injected s.c. as a substratum for angiogenesis. The synthesis of PAF was concomitant with the early migration of endothelial cells and infiltration of MAC-1-positive macrophages. Infiltration of lymphocytes and polymorphonuclear leukocytes was never observed. In vitro studies demonstrated that mouse peritoneal macrophages, but not two murine microvascular endothelial cell lines or human and bovine endothelial cells from large vessels, synthesized PAF after stimulation with HGF. Furthermore, macrophages expressed the transcript of HGF receptor encoded by the MET proto-oncogene and migrated after HGF challenge. The binding of HGF to its receptor was followed by the activation of the receptor tyrosine kinase domain and phosphorylation of the beta subunit. Leukocyte depletion with 5-fluorouracil and anti-MAC-1 Ab added to matrigel prevented the infiltration of macrophages, the synthesis of PAF and the angiogenesis induced by HGF. PAF extracted and purified from mice challenged with HGF induced a rapid angiogenic response, inhibited by WEB 2170. These results suggest that the angiogenic effect of HGF in vivo is mediated, at least in part, by PAF synthesized from macrophages infiltrating the matrigel plug.

Animals↗
PubMed1996

Cadmium injures tube formation by cultured human vascular endothelial cells.

The effect of cadmium chloride (Cd; CdCl2) on the tube formation by cultured human umbilical vascular endothelial cells (HUVEC) was examined. HUVEC were collected by enzymatic digestion with collagenase. Tube formation was studied by culturing the cells on a gelled basement membrane matrix (Matrigel). Treatment of HUVEC with 0.1 microM-1.0 mM Cd for 24 hours inhibited tube formation dose-dependently. The cadmium concentration inhibiting tube formation by 50% relative to untreated cells was about 150 microM. The length of tube formation decreased time-dependently with 150 microM Cd. The treatment of HUVEC by 50 nM of beta-phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C, increased tube formation. However, the inhibitory effect of Cd on tube formation was not affected by the addition of PMA. The pretreatment of the Matrigel by Cd inhibited tube formation similarly to the results of Cd treatment. These findings suggest that Cd inhibits the formation of a capillary network by HUVEC, and that the Cd-inhibitory effect on tube formation may have been dependent in this study on the degeneration of Matrigel by Cd.

Cadmium Chloride↗
PubMed1998

Proteolytic activity of human non-Hodgkin's lymphomas.

This study was conducted to assess the net proteolytic activity of human non-Hodgkin's lymphomas (NHLs). We have compared the extracellular matrix (ECM)-degradative abilities of human NHLs, reactive lymphoid hyperplasias, and established lymphoid cell lines using Matrigel invasion and elastin degradation assays. The inhibition studies allowed identification of the classes of proteinases involved in ECM degradation. Our results indicate that lymphocytes and other leukocytes derived from both human NHLs and reactive lymphoid hyperplasias are capable of Matrigel penetration, but only cells derived from the high-grade human NHLs degrade elastin in vitro. Established lymphoid cell lines (both malignant and Epstein-Barr virus immortalized) do not produce MMP-9, do not penetrate the Matrigel, and do not degrade elastin. Moreover, in human NHLs, elastolytic activity is blocked by metalloproteinase inhibitors, while inhibitors of the other classes of proteolytic enzymes have only minor effects. This study identifies metalloproteinases as the most important class of proteinases involved in ECM degradation by NHLs. The previous studies suggest that, within this class, MMP-9 represents the key enzyme that plays a role in the biological aggressiveness of human NHLs.

Cell Line↗
PubMed1997

Suppression of adhesion-induced protein tyrosine phosphorylation decreases invasive and metastatic potentials of B16-BL6 melanoma cells by protein tyrosine kinase inhibitor genistein.

Protein tyrosine kinase (PTK) appears to be involved in the activation of signaling during cell attachment to and spreading on extracellular matrix (ECM) in the metastatic cascade. To verify the assumption that PTK inhibitors might impair ECM signaling and prevent cancer metastasis, the highly metastatic B16-BL6 mouse melanoma cells were exposed to the PTK inhibitor genistein for 3 days. The ability of the cells to invade through reconstituted basement membrane (Matrigel) and to establish experimental pulmonary metastatic foci in C57BL/6 mice decreased after genistein exposure. The genistein-treated cells were also prevented from attaching to Matrigel and spread extremely poorly on the ECM substratum. Immunoblot analysis showed that tyrosine phosphorylation of a 125-kD protein in response to cell spreading on Matrigel was suppressed in the genistein-treated cells. Adhesion-induced protein tyrosine phosphorylation represents the earlier and specific event in the activation of ECM signaling, so this result implied ECM signaling was impaired in the treated cells. With immunofluorescence microscopy, the adhesion-induced tyrosine phosphorylated proteins were located at the pericytoplasms of well-spread cells, but not at the periphery of poorly spread genistein-treated cells. Therefore, this paper suggests that genistein might impair ECM signaling and subsequently prevent cancer cells from spreading well and invading or establishing metastasis through the suppression of adhesion-induced protein tyrosine phosphorylation. PTKs and adhesion-induced protein tyrosine phosphorylation might play a role in the control of invasion and metastasis.

Animals↗
PubMed2025

Interrogating functional connectivity of in vitro neural glia tissue model modulated through integrative control of matrix stiffness and a neurotrophic factor.

Brain function emerges from intricate cellular communication within neural networks. Both In silico neuronal models and primary neuron cells have revealed that the branching architecture of individual neurons determines the bioelectrical signal propagation pattern and dynamics. However, whether stem cell-differentiated neurons can build functional connectivity regulated by neuronal morphology has yet to be determined. Here, we hypothesized that neurite length, branching, or both factors would regulate the functional connectivity of the stem cell-differentiated neural network. We examined this hypothesis by differentiating mouse cortical neural stem cells (NSCs) on Matrigel substrates with varying storage moduli, both with and without basic fibroblast growth factor (bFGF). Interestingly, with bFGF, Matrigel with a storage modulus (G') of 100 Pa drives NSCs to differentiate into neurons with more dendritic branches, while the gel with G' of 50 Pa led to the development of longer neurites with fewer branches. Notably, branch-rich neural networks exhibited an increased frequency of calcium transients. Using a MATLAB-based analysis pipeline incorporating graph theory, we constructed spatial and temporal calcium activity maps, revealing that branching complexity, more than neurite length, correlates with the density and strength of functional neural circuits. Overall, this study demonstrates that the dendritic branching of neurons, modulated with matrix stiffness and neurotrophic factors, is a key element in enhancing the electrophysiological functionality of the stem cell-differentiated neural network. This finding will have a significant impact on efforts to reconstruct functional neural tissue models, advancing both regenerative therapies and unexplored applications, including biological computing.

Animals↗
PubMed2001

The mucosal invasion model: a novel in vitro model for evaluating the invasive behavior of mucocutaneous malignancies.

BACKGROUND: Prevention of regional and metastatic spread of cutaneous malignancies requires understanding the physiologic mechanism of tumor cell invasion. In vitro models are convenient for studying the in vitro invasive phenotype of normal cells, tumor cell lines, or genetically altered cells in a 3-dimensional matrix, but they should attempt to recapitulate the complex in vivo submucosal environment. A new acellular extracellular matrix, porcine submucosal matrix (PSM), is thought to accurately recapitulate the submucosal matrix. A novel in vitro model using PSM to assess mucocutaneous tumor cell invasion was studied. METHODS: The morphologic characteristics, growth, and invasive behavior of human head and neck squamous cell carcinoma (UM-SCC-1, UM-SCC-5, UM-SCC-17B, and OSC-19) cell lines were assessed on the PSM gel and compared with commonly used in vitro invasion models (type I collagen and Matrigel matrices). The invasive phenotype of canine kidney cells was also assessed on each matrix, because this cell line is known to demonstrate a characteristic in vitro invasive phenotype. RESULTS: The PSM-supported head and neck squamous cell carcinoma tumor cell line growth and single cell invasion were seen under stimulated conditions, similar to type I collagen gels. The invasive phenotype of canine kidney cells behaved similarly on PSM and collagen. Matrigel did not support growth well, and invasion occurred only superficially in isolated areas. CONCLUSION: The PSM is a good in vitro model for assessment of pharmacologic and genetic manipulations of head and neck squamous cell carcinoma tumor cell lines and has several advantages over other commonly used matrices.

Animals↗
PubMed1998

Cell-cell interactions during transendothelial migration of tumor cells.

A key event in cancer metastasis is the transendothelial migration of tumor cells. This process involves multiple adhesive interactions between tumor cells and the endothelium. After adhering to the surface of endothelial cells, tumor cells must penetrate the endothelial junction, which contains high concentrations of the cell adhesion molecules VE-cadherin and PECAM-1. Studies using an in vitro model system, consisting of melanoma cells which are seeded onto a monolayer of endothelial cells cultured on Matrigel, have revealed reorganization of the cytoskeleton and dynamic changes in the cell shape of both tumor and endothelial cells. The initial stages of transmigration are characterized by numerous membrane blebs protruding from the basolateral surfaces of the melanoma cells. Contact regions also show an abundance of microfilaments arising from the underlying endothelial cells. These adhesive interactions lead to the redistribution of both VE-cadherin and PECAM-1 and, consequently, a localized dissolution of the endothelial junction. The penetration of the endothelial junction is initiated by melanoma pseudopods. Despite the disappearance of VE-cadherin from the retracting endothelial junction, heterotypic contacts between the tumor cell and its surrounding endothelial cells show a high concentration of pan-cadherin staining, suggesting that transmigration of melanoma cells might yet be facilitated by interactions with another member of the cadherin family. Upon adhesion to the Matrigel, melanoma cells begin to spread and invade the matrix material, while the endothelial cells extend processes over the melanoma cells to reform the monolayer. Interestingly, the leading margins of these endothelial processes contain a high concentration ofN-cadherin. VE-cadherin and PECAM-1 reappear only when the advancing endothelial processes meet to reform the endothelial junction. Together, these observations suggest that endothelial cells actively participate in the transmigration of tumor cells and specific cadherins are involved in different steps of this complex process.

Animals↗
PubMed1997

Quantification of integrin subunits on human prostatic cell lines--comparison of nontumorigenic and tumorigenic lines.

BACKGROUND: We set out to quantify integrin subunits on the surface of several prostate cell lines, including two nontumorigenic lines, in order to assess their role in tumorigenicity and metastasis. METHODS: Flow cytometry was used to estimate the amounts of each subunit by changes in mean fluorescence intensity from control antibody. An in vitro Matrigel (Collaborative Biomedical Products, Bedford, MA) assay was used to determine invasiveness. RESULTS: Profiles of each cell line were developed using the change in subunit mean fluorescence intensity normalized to the beta 1-subunit. The alpha 4-subunit is only expressed on nontumorigenic cells. These same cells were unable to invade Matrigel. CONCLUSIONS: Comparison of nontumorigenic and cancerous lines suggests that a loss of the alpha 4-subunit correlates with the acquisition of tumorigenicity and perhaps metastatic potential. The ability to quantify expression of integrin subunits on prostate cell lines allows the determination of regulation by factors responsible for growth, tumorigenicity, and/or metastasis.

Antibodies, Monoclonal↗
PubMed1999

Elevated expression of FGF-2 does not cause prostate cancer progression in LNCaP cells.

BACKGROUND: Androgen-independent (AI) prostate cancer (CaP) resulting from progression of disease is untreatable. Such progression may relate to upregulation and autocrinicity of growth factor expression. We studied one candidate growth factor, basic fibroblast growth factor (FGF-2). METHODS: LNCaP cells made autocrine for FGF-2 by stable transfection with FGF-2 were examined for cancer progression, measured by 1) altered response to androgen, 2) ability to grow more quickly when cocultured with bone cells in vitro or to form tumors when coinoculated with bone cells in vivo, or 3) increase in metastatic ability. RESULTS: Stably transfected lines differed in FGF-2 protein expression. LNCaP-HF (high production of FGF-2) expressed more FGF-2 than LNCaP-LF (low production of FGF-2); controls were negative. In vitro, compared with LNCaPs, LNCaP-HF cells showed a slightly increased growth rate, reduced proliferation in response to androgen but not to estrogen or progesterone, and a decreased proliferative response to epidermal growth factor (EGF) and FGF-2. Although giving a slightly faster take rate, LNCaP-HF cells without Matrigel only formed small, fast-regressing tumors in male nude mice, and with Matrigel, did not differ from LNCaPs in growth rate or tumor size. No metastases occurred. No tumors grew in females. Mixed growth of FGF-2 transfectants with human fetal osteoblasts failed to cross-stimulate in vitro, or to allow tumor formation in vivo. CONCLUSIONS: Although FGF-2 is overexpressed in AI CaPs, our experiments show that upregulation of FGF-2 expression is not sufficient to cause androgen independence, tumorigenicity, or metastases production (i.e., prostate cancer progression) in LNCaP cells.

Animals↗
PubMed1997

Role of cadherins in the transendothelial migration of melanoma cells in culture.

Transmigration of cancer cells through the vascular endothelium (diapedesis) is a key event in tumor metastasis. To investigate mechanisms involved in diapedesis, we used laser scanning confocal microscopy to examine the distribution of cadherins of WM239 melanoma cells as they migrated through a monolayer of activated human umbilical vein endothelial cells (EC) cultured on matrigel. Cadherins, including VE-cadherin, but not N-cadherin, were enriched in contacts between EC, whereas N-cadherin, but not VE-cadherin, was found in contacts between melanoma cells. During the early stages of diapedesis, EC located below the attached melanoma cells decreased in height and VE-cadherin disappeared from the EC contact located underneath the melanoma cell. Transendothelial migration began with small melanoma cell processes penetrating the VE-cadherin-negative regions between the EC. Subsequently, melanoma cells became intercalated between EC. Despite the absence of both VE-cadherin and N-cadherin, other members of the cadherin family were present in the heterotypic contacts between EC and melanoma cells. EC surrounding the intercalated melanoma cell subsequently extended processes and spread over the melanoma cell to re-form the endothelial monolayer. Interestingly, the leading margins of these EC processes contained high levels of N-cadherin, but not VE-cadherin. VE-cadherin-rich cell-cell contacts, however, reformed between advancing endothelial processes when they met above the melanoma cell. As the melanoma cells came into contact with the underlying matrigel, they spread out and adopted a fibroblast-like morphology. Addition of anti-N-cadherin antibodies to the assay resulted in a delay in the transendothelial migration of melanoma cells. Together, these results suggest that EC actively participate in diapedesis by disassembling and reassembling VE-cadherin-rich adherens junctions, and that N-cadherin plays an important role in the transmigration of melanoma cells and the reclosure of the endothelium.

Antibodies, Monoclonal↗
PubMed1998

Invasion potential and N-acetylgalactosamine expression in a human melanoma model.

Reactivity of the N-acetylgalactosamine-binding Helix pomatia agglutinin (HPA) in tumours has been associated with poor prognosis and metastasis development. In our LOX/FEMX-I human melanoma model, the binding of HPA correlates with experimental lung metastasis formation in athymic nude mice. In the present study, the metastatic potential of 2 human melanoma cell lines (LOX and FEMX-I) was assessed in relation to carbohydrate and invasive phenotype. Immunocytological and invasion assays highlighted significant differences between these 2 cell lines. Immuno-cytochemical analysis confirmed the widespread expression of HPA-binding glycoconjugates on LOX but not FEMX-I cells. One of these HPA-binding glycoconjugates, the Tn antigen, was expressed highly on the surface of LOX cells but only weakly in the cytoplasm of FEMX-I cells. The sialyl Tn antigen was expressed in FEMX-I but not in LOX cells. There was no difference between the cell lines in adhesion/rate of trapping in athymic nude mouse lung tissues. In Matrigel invasion assays, LOX cells demonstrated an invasion potential more than 6 times greater than that observed with FEMX-I cells. Matrigel invasion of LOX cells was inhibited after incubation with HPA (89%) compared to controls with HPA and GalNAc blocking sugar or without HPA (p < 0.0005 at 5 df). In contrast, there was no inhibitory effect with the anti-Tn antibody IE3. Invasion of FEMX-I cells was not affected by the lectin and the IE3 antibody. Immuno-cytochemical analysis revealed expression of the terminal galactose- and polylactosamine-binding lectin galectin 3 (Mac-2) in these melanoma cell lines. Expression of both the lectin and its receptor may be a contributory feature in the pulmonary invasion of LOX melanoma cells. Overall, our findings suggest that HPA-binding glycoconjugates other than the alphaGalNAc-O-Ser/Thr of the Tn antigen may be important in the extracellular matrix invasion of LOX melanoma cells.

Acetylgalactosamine↗
PubMed1998

5alpha-reductase and 17beta-hydroxysteroid dehydrogenase expression in epithelial cells from hyperplastic and malignant human prostate.

The aim of this study on testosterone (T) metabolism in benign prostatic hyperplasia (BPH) and prostatic cancer was to compare the formation of metabolites in freshly isolated epithelial cells and in cells of long-term cultures (2 passages) and to identify the 5alpha-reductase (5alpha-R) and 17beta-hydroxysteroid dehydrogenase (17beta-HSD) isoforms responsible for metabolite formation. Androst-4-enedione (A), dihydrotestosterone (DHT) and 5alpha-androstanedione (5alpha-A) formation were measured by high-performance liquid chromatography coupled to a Flo-one HP radioactivity detector. Enzyme isoforms were studied by Northern blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR). T conversion into A by 17beta-HSD, rather than reduction into DHT by 5alpha-R, was by far the predominant activity in cultured epithelial cells. The metabolic profile did not differ substantially between BPH and cancer cells. Long-term cell culture led to an increase in A formation compared with the level recorded in freshly isolated cells, with no significant incidence on the relative DHT level. According to RT-PCR results, both 5alpha-R isoforms (1 and 2) and 2 17beta-HSD isoforms (2 and 3) are present in epithelial cell cultures and in tissues. According to Northern blot analyses, the mRNAs for 5alpha-R2 and 17beta-HSD4 are expressed in tissue and those for 5alpha-R1 and types 2 and 4 17beta-HSD in isolated cell cultures. Moreover, finasteride, a specific 5alpha-R2 inhibitor, inhibits DHT and 5alpha-A formation in long-term cell culture of adenocarcinoma epithelial cells plated on Matrigel, suggesting a 5alpha-R2 expression. Thus, although 5alpha-R2 is present in freshly isolated epithelial cell cultures and in long-term epithelial cells cultured on Matrigel and predominates in prostate tissue, it is the 5alpha-R1 isoform that is preferentially expressed in epithelial cell cultures.

17-Hydroxysteroid Dehydrogenases↗