Differences in Caco-2 cell attachment, migration on collagen and fibronectin coated polyelectrolyte surfaces

Metastasis mechanisms depend on cell metabolism changes, migration and adhesion to different tissues. To understand their choice of interaction site, the tumoral cell adhesion to model surfaces was studied. The response of Caco-2 tumoral cells cultured on polyelectrolyte film-functionalized surfaces with or without adhesion proteins (fibronectin or collagen IV) was analyzed. Using the layer-by- layer method, multilayer films were prepared with cationic poly(allylamine hydrochloride) and anionic poly(sodium 4-styrenesulfonate) polyelectrolytes. Film surface wettability was evaluated. The electrochemical impedance spectroscopy analyses were carried out to control the elaborated surfaces on which Caco-2 tumoral cells were cultured. The cell velocity was studied by video-microscopy and a cell colorimetric assay (WST-1) was used to quantify cell viability. The film surface parameters as well as the protein nature and localization in the film were found to modulate cell response. Results demonstrated that the cancer cell motility and proliferation were higher when cultured onto pure collagen located above the polyelectrolyte film and that the reverse surprisingly was observed when proteins were inserted into the polyelectrolyte film. Data also showed that cell motility was correlated with a high charge transfer resistance (Rct) and a low surface free energy (SFE) polar component (electron donor character). This relationship was valid only for pure external proteins. Thus, fibronectin exhibited a low Rct and a high SFE polar component, which decreased cell motility and proliferation.     

Polydimethylsiloxane Films Modified with Chitosan/Pectin Multilayers as Scaffolds for Mesenchymal Stem Cells

Solid (smooth) and porous films of polydimethylsiloxane (PDMS) have been obtained; the effect of their structure on the adhesion of mesenchymal stem cells (MSCs) on their surface was found. It is shown that modification of these films with a (chitosan/pectin)₄ multilayer increased the efficiency of viable cell adhesion. A (3-aminopropyl)triethoxysilane–glutaraldehyde system was used to enhance the binding of the polysaccharide layer to the hydrophobic surface of PDMS. It was found that MSCs formed a monolayer culture of the fibroblast-like cells with high viability on porous PDMS modified with (chitosan/pectin)₄.     

A chemical surface modification of chitosan by glycoconjugates to enhance the cell-biomaterial interaction

The use of wheat germ agglutinin (WGA), a lectin molecule, to modify chitosan and enhance the cell-biomaterial interaction was examined. The percentage of living fibroblast cells on the surfaces of tissue culture polystyrene (TCPS) control, WGA-modified chitosan, and unmodified chitosan films increased to 99%, 99%, and 85%, respectively, after seeding for 48 h. DNA staining revealed that a portion of fibroblasts cultivated on chitosan films( )were undergoing apoptosis. In contrast, fibroblasts growing on WGA-modified chitosan film surfaces did not show any indication of apoptosis. The number of fibroblast cells was the highest on the WGA-modified chitosan surfaces, followed by the TCPS and unmodified chitosan surfaces. This WGA-mediated enhancement on the fibroblast cell-biomaterial interaction was cell type dependent. Other types of cells may need different lectin molecules for enhanced interaction with biomaterials. Further, the evaluation of the heat shock protein (HSP) mRNA expression indicated that HSP 90 expression was increased in the fibroblast cells cultivated on chitosan films and decreased to basal levels on the WGA-modified chitosan films. Taken together, our data suggest that the use of WGA and other lectin molecules to enhance the cell-biomaterial interaction via oligosaccharide-mediated cell adhesion is a promising way to improve cell adhesion and proliferation, the two key issues in tissue engineering.     

通过研究改性壳聚糖与细胞的相互作用评价其生物相容性

利用细胞生物学的方法, 研究了四种不同的细胞在经过改性的壳聚糖（ＣＨＩＴＯＳＡＮ） 膜上的生长,测定了细胞相对黏附力、细胞初始黏附率, 并利用ＦＤＡ 实验测定了细胞活力,从而从多个方面评价了这几种不同材料的生物相容性。实验结果表明,与明胶交联的壳聚糖膜明显比其它两种膜有利于细胞的黏附和生长,为进一步对材料进行筛选奠定了基础。     

Laser effects on cellular adhesion and influence on the interrelation between HeLa S3 and human diploid cells

The interactions between HeLa S3 tumoral cells and human fibroblasts after nitrogen-laser irradiation (337.1 nm) have been studied by using an in vitro cell invasion model. For the quantitative and morphological evaluation of nitrogen-laser radiation action upon tumoral adhesion to the fibroblast monostrate, we used: a) 3H-thymidine labelling of HeLa S3 tumoral cells; b) morphological modifications studies by phase contrast and scanning electron microscopy. The results emphasized the following aspects: 1. In non-irradiated cell cultures we noticed three interaction stages: adhesion, tumoral spreading and displacement with fibroblasts destruction; on the other side, we found a reduced adhesion to non-irradiated human fibroblasts of laser irradiated tumoral cells. 2. Significant percent increasing of non-irradiated tumoral cells adhesion to fibroblast monostrate, irradiated with various laser fluences (e.g. 0.2 kJ/m2--48.1%; 0.8 kJ/m2--63.8% and for 1.6 kJ/m2--79.5%). This phenomenon evidenced the close interrelation between irradiation fluences and tumoral adhesion rates. 3. The importance of numerical ratio between tumoral cells and fibroblasts in tumoral adhesion and invasion processes (e.g. ratio 1:10 tumoral adhesion reached 8.1%; in 1:5--25.9%; in 1:1--59.4% and for 2:1--83.9%). 4. Marked cytotoxic effects for both cell types after exposure to high and very high laser fluences (1.6--6.4 kJ/m2). Our results emphasize near UV-laser irradiation effects upon some of tumoral adhesion and invasion mechanisms and demonstrate the interrelations between cell populations manifesting a different vital potential.     

壳聚糖和明胶材料对血管平滑肌细胞的作用

壳聚糖是一种具有发展前景的生物材料。研究了不同脱乙酰度壳聚糖、明胶及壳聚糖与明胶共混材料对血管平滑肌细胞生长的促进作用。在不同材料上培养细胞,采集培养后第1天和第5天的图像．在培养24、72、120h时做MTT实验。此外,还用酶联免疫检测(ELISA)方法测量了材料吸附细胞外基质蛋白的数量,探讨细胞外基质蛋白在血管平滑肌细胞与材料相互作用中所起的作用。结果表明脱乙酰度高的壳聚糖材料能较好地促进血管平滑肌细胞的粘附、铺展和生长,可能是一种具有一定应用前景的血管组织工程研究用材料。     

The Inhibitory Effect of an RGD-Human Chitin-Binding Domain Fusion Protein on the Adhesion of Fibroblasts to Reacetylated Chitosan Films

Biomaterials used for tissue engineering applications must provide a structural support for the tissue development and also actively interact with cells, promoting adhesion, proliferation, and differentiation. To achieve this goal, adhesion molecules may be used, such as the tripeptide Arg-Gly-Asp (RGD). A method based on the use of a carbohydrate-binding module, with affinity for chitin, was tested as an alternative approach to the chemical grafting of bioactive peptides. This approach would simultaneously allow the production of recombinant peptides (alternatively to peptide synthesis) and provide a simple way for the specific and strong adsorption of the peptides to the biomaterial. A fusion recombinant protein, containing the RGD sequence fused to a human chitin-binding module (ChBM), was expressed in E. coli. The adhesion of fibroblasts to reacetylated chitosan (RC) films was the model system selected to analyze the properties of the obtained proteins. Thus, the evaluation of cell attachment and proliferation on polystyrene surfaces and reacetylated chitosan films, coated with the recombinant proteins, was performed using mouse embryo fibroblasts 3T3. The results show that the recombinant proteins affect negatively fibroblasts anchorage to the materials surface, inhibiting its adhesion and proliferation. We also conclude that this negative effect is fundamentally due to the human chitin-binding domain.     

Adhesion and growth of HUVEC endothelial cells on films of enzymatically functionalized chitosan with phenolic compounds

Human Umbilical Vein Endothelial Cell (HUVEC) growth on chitosan films and its enzymatically functionalized derivatives films with ferulic acid (FA) and ethyl ferulate (EF) was assessed by evaluating cell adhesion, morphology and cell viability. The results indicated that chitosan derivative films improved protein adsorption properties compared to chitosan films. The HUVEC cell morphology showed well attachment and spread phenotype on chitosan derivative films compared to those growing on chitosan films which did not spread and remained round. Evaluation of cell viability revealed improvement of cell adhesion on chitosan derivative films compared to chitosan film depending on the quantity of oxidized phenols grafted on chitosan. In addition, FA-/EF-chitosan films allowed almost similar cell adhesion. Furthermore, cell adhesion was increased with the film thickness. These results suggested that the oxidized phenols grafting on chitosan is a promising process to enhance cell adhesion, growth and creating useful functional biomaterials.     

Myoblast adhesion and proliferation on biodegradable polymer films with femtosecond laser‐fabricated micro through‐holes

Controlling cell adhesion and cell differentiation is necessary to fabricate a tissue with arbitrary properties for tissue engineering applications. A substrate with a porous structure as a cell scaffold allows the diffusion of the cell culture medium through the scaffold. In this work, we show that the femtosecond laser fabricated micro through‐holes in biodegradable polymer films, enhance myoblast adhesion, and accelerates proliferation and differentiation. ChR2‐C2C12 and UT‐C2C12 cells were seeded on the films with micro through‐holes each fabricated by a single femtosecond laser pulse. Cell adhesion was enhanced on films with holes fabricated by laser irradiation. In addition, cell proliferation was accelerated on films with micro through‐holes that penetrate the film, compared to on films with micro craters that do not penetrate the film. On films with arrays consisting of micro through‐holes, cells aligned along the arrays and cell fusion was enhanced, indicating the acceleration of cell differentiation.     

Mannose receptor-mediated endothelial cell activation contributes to B16 melanoma cell adhesion and metastasis in liver

The role of mannose receptors from hepatic sinusoidal endothelium (HSE) in liver colonization by B16 melanoma (B16M) cells was studied. The expression of high mannose-type oligosaccharides on the surface of B16M cells was enhanced by in vitro treatment with 1-deoximannojirimycin (1-DMM). There was a significant (P < 0.01) enhancement of hepatic metastasis when B16M cells were 1-DMM-treated before being intrasplenically injected into C57BL/6J mice. Intraperitoneal administration of 5 mg/kg recombinant human interleukin-1 receptor antagonist (rHuIL-1Ra) inhibited the 1-DMM-induced enhancement of metastasis. Expression of high mannose-type oligosaccharides on the surface of 1-DMM-treated B16M cells and their in vitro adhesion to the HSE was significantly correlated (R = 0.82). The addition of either 100 μg/ml mannan or paraformaldehyde (PFA)-fixed 1-DMM-treated B16M cells to cultured HSE for a period of 12 h significantly (P < 0.01) increased the release of IL-1β from the HSE compared to that liberated by the HSE incubated with either basal medium or PFA-fixed untreated B16M cells. The same HSE treatments also significantly (P < 0.01) increased the degree of adhesion of other B16M cells to HSE, being abrogated by anti-mouse vascular cell adhesion molecule-1 (VCAM-1) antibodies. The conditioned media from HSE cultures, activated by PFA-fixed, 1-DMM-treated B16M cells significantly (P < 0.01) increased B16M cell proliferation when compared to conditioned media from HSE cultures incubated with PFA-fixed, untreated B16M cells. Thus, 1-DMM treatment of B16M cells enhanced the development of hepatic metastasis by IL-1-dependent mechanisms. The mechanism is consistent with in vitro mannose receptor-mediated melanoma cell attachment to the HSE, which subsequently upregulates IL-1β release, VCAM-1-dependent adherence, and melanoma growth factor(s) release by HSE. J. Cell. Physiol. 174:322–330, 1998. © 1998 Wiley-Liss, Inc.     

Improved blood biocompatibility of composite film of chitosan/carbon nanotubes complex

Single-walled carbon nanotubes are novel molecular-scale wires having excellent anti-adhesion properties with regard to platelets. On the other hand, chitosan is a partially de-acetylated derivative of chitin that has a critical role in cell attachment and growth. The aim of this study was to investigate how carbon nanotubes improve the blood biocompatibility of chitosan film. We prepared composite films with various concentrations of chitosan/carbon nanotubes (CS/CNTs) (1.3–6.3 wt%). The sample surfaces were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurements. The surface characterization revealed that the surface of the CS/CNTs composite film became more hydrophobic with increasing amounts of CNTs. Cell attachment tests using bovine aortic endothelial cells (BAECs) indicated that CS/CNTs composite films retained their cell adhesion ability. The blood compatibility of the CS/CNTs composite films was evaluated using the blood platelet adhesion and activation tests in vitro. Platelet adhesion results confirmed that platelet adhesion and the formation of a platelet network were inhibited on composite films with higher concentrations of CNTs (5.1 wt%). Our experimental results show that the novel composite film containing CS/CNTs possesses two paradoxical characteristics, namely, good adherence of endothelial cells and minimum adherence and activation of platelets, making this film a promising antithrombogenic material for use in the biomedical field.     

Vascular smooth muscle cells on polyelectrolyte multilayers: hydrophobicity-directed adhesion and growth

Polyelectrolyte multilayer films were employed to support attachment of cultured rat aortic smooth muscle A7r5 cells. Like smooth muscle cells in vivo, cultured A7r5 cells are capable of converting between a nonmotile "contractile" phenotype and a motile "synthetic" phenotype. Polyelectrolyte films were designed to examine the effect of surface charge and hydrophobicity on cell adhesion, morphology, and motility. The hydrophobic nature and surface charge of different polyelectrolyte films significantly affected A7r5 cell attachment and spreading. In general, hydrophobic polyelectrolyte film surfaces, regardless of formal charge, were found to be more cytophilic than hydrophilic surfaces. On the most hydrophobic surfaces, the A7r5 cells adhered, spread, and exhibited little indication of motility, whereas on the most hydrophilic surfaces, the cells adhered poorly if at all and when present on the surface displayed characteristics of being highly motile. The two surfaces that minimized cell adhesion consisted of two varieties of a diblock copolymer containing hydrophilic poly(ethylene oxide) and a copolymer bearing a zwitterionic group AEDAPS, (3-[2-(acrylamido)-ethyldimethyl ammonio] propane sulfonate). Increasing the proportion of AEDAPS in the copolymer decreased the adhesion of cells to the surface. Cells presented with micropatterns of cytophilic and cytophobic surfaces generated by polymer-on-polymer stamping displayed a surface-dependent cytoskeletal organization and a dramatic preference for adhesion to, and spreading on, the cytophilic surface, demonstrating the utility of polyelectrolyte films in manipulating smooth muscle cell adhesion and behavior.     

Development of a chitosan nanofibrillar scaffold for skin repair and regeneration

The final goal of the present study was the development of a 3-D chitosan dressing that would shorten the healing time of skin wounds by stimulating migration, invasion, and proliferation of the relevant cutaneous resident cells. Three-dimensional chitosan nanofibrillar scaffolds produced by electrospinning were compared with evaporated films and freeze-dried sponges for their biological properties. The nanofibrillar structure strongly improved cell adhesion and proliferation in vitro. When implanted in mice, the nanofibrillar scaffold was colonized by mesenchymal cells and blood vessels. Accumulation of collagen fibrils was also observed. In contrast, sponges induced a foreign body granuloma. When used as a dressing covering full-thickness skin wounds in mice, chitosan nanofibrils induced a faster regeneration of both the epidermis and dermis compartments. Altogether our data illustrate the critical importance of the nanofibrillar structure of chitosan devices for their full biocompatibility and demonstrate the significant beneficial effect of chitosan as a wound-healing biomaterial.     

Effects of Carbon Nanotubes in a Chitosan/Collagen-Based Composite on Mouse Fibroblast Cell Proliferation

This study investigated the in vitro cytocompatibility of carbon nanotubes (CNTs) in a chitosan/collagen-based composite. Mouse fibroblasts were cultured on the surface of a novel material consisting of CNTs in a chitosan/collagen-based composite (chitosan/collagen+CNTs group). Chitosan/collagen composites without CNTs served as the control material (chitosan/collagen group) and cells cultured normally in tissue culture plates served as blank controls (blank control group). Cell adhesion and proliferation were observed, and cell apoptosis was measured. The doubling time (DT₁) of cells was significantly shorter in the chitosan/collagen+CNTs group than in the chitosan/collagen group, and that in the chitosan/collagen group was shorter than in the blank control group. The CNTs in the chitosan/collagen-based composites promoted mouse fibroblast adhesion, producing a distinct cytoskeletal structure. At 24 h after culture, the cytoskeleton of the cells in the chitosan/collagen+CNTs group displayed typical fibroblastic morphology, with clear microfilaments. Cells in the chitosan/collagen group were typically round, with an unclear cytoskeleton. The blank control group even had a few unattached cells. At 4 days after incubation, no early apoptosis of cells was detected in the blank control group, whereas early apoptosis of cells was observed in the chitosan/collagen+CNTs and chitosan/collagen groups. No significant difference in the proportion of living cells was detected among the three groups. After entering the plateau stage, the average cell number in the chitosan/collagen+CNTs group was similar to that in the chitosan/collagen group and significantly smaller than that in the blank control group. Early apoptosis of cells in the blank control group was not detectable. There were significant differences in early apoptosis among the three groups. These results suggest that CNTs in a chitosan/collagen-based composite did not cause significant cytotoxic effects on mouse fibroblasts. Compared with chitosan/collagen composites, early adhesion and proliferation of fibroblasts were increased on chitosan/collagen+CNTs. However, at relatively high cell densities, the CNTs in the chitosan/collagen-based composite might exert an inhibitory effect on mouse fibroblast proliferation by inducing apoptosis.     

Effect of molecular weight of chitosan on antimicrobial properties and tissue compatibility of chitosan-impregnated bacterial cellulose films

Bacterial cellulose-chitosan (BC-C) films were developed by immersing purified BC pellicles in 1.5 ~ 2.0% (w/v) acetic acid solutions containing chitosan of varying molecular weights. Effects of different molecular weight of chitosan on physical, biological and antimicrobial properties of the composite films were investigated. The cumulative chitosan absorption capacities with M_w of 141,000, 199,000, and 263,000 were 38.43, 24.65, and 23.89 mg/cm³ of dry BC film, respectively. The cumulative release profiles of chitosan from the films strongly depended on molecular weight of chitosan and pH of solution. The order of release of chitosan from the BC-C films was dependent on molecular weight as follows: M_w 141,000 > M_w 199,000 > M_w 263,000. All BC-C films showed the antimicrobial abilities against Staphylococcus aureus and Aspergillus niger but had no inhibitory effect on the growth of Escherichia coli. The BC-C films supported for adhesion, spreading and proliferation of both human skin keratinocytes and fibroblasts. The antibacterial activity against S. aureus of the BC-C with the highest Mw chitosan (263,000) was higher than those of the others. On the other hand, the BC-C films with the lowest M_w chitosan (141,000) promoted the growth of human skin cells more than those of the others.     

Pro-apoptotic versus anti-apoptotic properties of dietary resveratrol on tumoral and normal cardiac cells

Resveratrol is a natural dietary polyphenol found in grape skin, red wine, and various other food products. Resveratrol has proved to be an effective chemopreventive agent for different malignant tumors. It has also been shown to prevent vascular alterations such as atherosclerosis and inflammatory-associated events. In view of these observations, we investigated the anti-proliferative and pro-apoptotic activities of resveratrol on a tumoral cardiac cell line (HL-1 NB) derived from mouse tumoral atrial cardiac myocytes. These effects were compared with those found on normal neonatal mouse cardiomyocytes. HL-1 NB cells and neonatal cardiomyocytes were treated with resveratrol (5, 30, and/or 100 μM) for different times of culture (24, 48, and/or 72 h). Resveratrol effects were determined by various microscopical and flow cytometric methods. After resveratrol treatment, a strong inhibition of tumoral cardiac HL1-NB cell growth associated with a loss of cell adhesion was observed. This cell proliferation arrest was associated with an apoptotic process revealed by an increased percentage of cells with fragmented and/or condensed nuclei (characteristic of apoptotic cells) identified after staining with Hoechst 33342 and by the presence of cells in subG1. At the opposite, on normal cardiomyocytes, no cytotoxic effects of resveratrol were observed, and a protective effect of resveratrol against norepinephrine-induced apoptosis was found on normal cardiomyocytes. Altogether, the present data demonstrate that resveratrol (1) induces apoptosis of tumoral cardiac HL1-NB cells, (2) does not induce cell death on normal cardiomyocytes, and (3) prevents norepinephrine-induced apoptosis on normal cardiomyocytes.     

Mechanism of enhancement of microbial cell hydrophobicity by cationic polymers.

Polycationic polymers have been noted for their effects in promoting cell adhesion to various surfaces, but previous studies have failed to describe a mechanism dealing with this type of adhesion. In the present study, three polycationic polymers (chitosan, poly-L-lysine, and lysozyme) were tested for their effects on microbial hydrophobicity, as determined by adhesion to hydrocarbon and polystyrene. Test strains (Escherichia coli, Candida albicans, and a nonhydrophobic mutant, MR-481, derived from Acinetobacter calcoaceticus RAG-1) were vortexed with hexadecane in the presence of the various polycations, and the extent of adhesion was measured turbidimetrically. Adhesion of all three test strains rose from near zero values to over 90% in the presence of low concentrations of chitosan (125 to 250 micrograms/ml). Adhesion occurred by adsorption of chitosan directly to the cell surface, since E. coli cells preincubated in the presence of the polymer were highly adherent, whereas hexadecane droplets pretreated with chitosan were subsequently unable to bind untreated cells. Inorganic cations (Na+, Mg2+) inhibited the chitosan-mediated adhesion of E. coli to hexadecane, presumably by interfering with the electrostatic interactions responsible for adsorption of the polymer to the bacterial surface. Chitosan similarly promoted E. coli adhesion to polystyrene at concentrations slightly higher than those which mediated adhesion to hexadecane. Poly-L-lysine also promoted microbial adhesion to hexadecane, although at concentrations somewhat higher than those observed for chitosan. In order to study the effect of the cationic protein lysozyme, adhesion was studied at 0 degree C (to prevent enzymatic activity), using n-octane as the test hydrocarbon. Adhesion of E. coli increased by 70% in the presence of 80 micrograms of lysozyme per ml. When the negatively charged carboxylate residues on the E. coli cell surface were substituted for positively charged ammonium groups, the resulting cells became highly hydrophobic, even in the absence of polycations. The observed "hydrophobicity" of the microbial cells in the presence of polycations is thus probably due to a loss of surface electronegativity. The data suggest that enhancement of hydrophobicity by polycationic polymers is a general phenomenon.     

Inhibition by tyroserleutide (YSL) on the invasion and adhesion of the mouse melanoma cell

Tyroserleutide (YSL) is an active, low-molecular-weight polypeptide, comprised of three amino acids, that has shown antitumor effects on human hepatocarcinoma BEL-7402 in vitro and in vivo. In this study, we evaluated the inhibition of YSL on invasion and adhesion of the mouse B16-F10 melanoma cell line by injecting B16-F10 cells into the tail veins of C57BL/6 mice to establish an experimental lung metastasis model. YSL inhibited B16-F10 cell metastasis to lung, reducing the number and area of metastasis lesions. When we treated B16-F10 cells with YSL (0.01, 0.1, 1, 10, or 100 microg/mL) in vitro, we found that YSL inhibited the proliferation of B16-F10 cells with a 28.11% rate of inhibition. YSL significantly decreased the adhesiveness of B16-F10 cells to Matrigel with a 29.15% inhibition rate; YSL also significantly inhibited the invasion of B16-F10 cells, producing an inhibition of 35.31%. By analyses with Western blot and real-time RT-PCR, we found that YSL markedly inhibited the expression of ICAM-1 in B16-F10 cells. These data suggest that YSL inhibits the growth, invasion, and adhesion of B16-F10 cells.     

Differential role of beta(1C) and beta(1A) integrin cytoplasmic variants in modulating focal adhesion kinase, protein kinase B/AKT, and Ras/Mitogen-activated protein kinase pathways

The integrin cytoplasmic domain modulates cell proliferation, adhesion, migration, and intracellular signaling. The beta(1) integrin subunits, beta(1C) and beta(1A), that contain variant cytoplasmic domains differentially affect cell proliferation; beta(1C) inhibits proliferation, whereas beta(1A) promotes it. We investigated the ability of beta(1C) and beta(1A) to modulate integrin-mediated signaling events that affect cell proliferation and survival in Chinese hamster ovary stable cell lines expressing either human beta(1C) or human beta(1A). The different cytodomains of either beta(1C) or beta(1A) did not affect either association with the endogenous alpha(2), alpha(V), and alpha(5) subunits or cell adhesion to fibronectin or TS2/16, a mAb to human beta(1). Upon engagement of endogenous and exogenous integrins by fibronectin, cells expressing beta(1C) showed significantly inhibited extracellular signal-regulated kinase (ERK) 2 activation compared with beta(1A) stable cell lines. In contrast, focal adhesion kinase phosphorylation and Protein Kinase B/AKT activity were not affected. Selective engagement of the exogenously expressed beta(1C) by TS2/16 led to stimulation of Protein Kinase B/AKT phosphorylation but not of ERK2 activation; in contrast, beta(1A) engagement induced activation of both proteins. We show that Ras activation was strongly reduced in beta(1C) stable cell lines in response to fibronectin adhesion and that expression of constitutively active Ras, Ras 61 (L), rescued beta(1C)-mediated down-regulation of ERK2 activation. Inhibition of cell proliferation in beta(1C) stable cell lines was attributable to an inhibitory effect of beta(1C) on the Ras/MAP kinase pathway because expression of activated MAPK kinase rescued beta(1C) antiproliferative effect. These findings show that the beta(1C) variant, by means of a unique signaling mechanism, selectively inhibits the MAP kinase pathway by preventing Ras activation without affecting either survival signals stimulated by integrins or cellular interactions with the extracellular matrix. These findings highlight a role for beta(1)-specific cytodomain sequences in maintaining an intracellular balance of proliferation and survival signals.