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L T Furcht

Publications and source records attributed to L T Furcht.

At least 55 records · Page 3Linked to original sources
PubMed1992

Effect of glow discharge surface modification of plasma TFE vascular graft material on fibronectin and laminin retention and endothelial cell adhesion.

The effects of glow discharge surface modification of plasma TFE vascular graft material (plasma TFE, Atrium Medical Corp., Hollis, NH) on the binding and retention of fibronectin and laminin as well as endothelial adherence were examined. The binding of both fibronectin and laminin to plasma TFE increased as a function of protein concentration in the range of 0.02 to 200 micrograms/ml. Binding to plasma TFE was not saturable in this range of protein concentrations. Fibronectin and laminin binding to plasma TFE was time-dependent, reaching a maximal level (1.8 and 3.2 micrograms/cm2 of bound fibronectin and laminin, respectively) after 30 min (fibronectin) and 4 hr (laminin). Binding was not the result of an accumulation of unbound protein in graft interstices since graft prewetting did not alter the amount of either fibronectin or laminin associated with plasma TFE. In addition, binding was not the result of protein modification during radiolabeling, since unlabeled fibronectin and laminin could compete effectively with their iodinated counterparts for binding to plasma TFE. Dissociation of bound fibronectin and laminin from plasma TFE was rapid, and less than 12% remained bound 60 min after washing. Plasma TFE subjected to glow discharge in O2 and carrying negatively charged functional groups on graft surfaces, exhibited a fivefold increase in fibronectin and laminin binding. In addition, more than 85% of the bound fibronectin and laminin was retained 24 hr after washing. The enhanced retention of fibronectin or laminin by these grafts was associated with an increase in endothelial cell adhesion.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗
PubMed1992

A synthetic peptide derived from the carboxy terminus of the laminin A chain represents a binding site for the alpha 3 beta 1 integrin.

The purpose of this study was to identify the binding site(s) within laminin for the alpha 3 beta 1 integrin receptor. It has been previously shown, using proteolytic fragments and anti-laminin antibodies, that the region in laminin for alpha 3 beta 1 integrin binding is localized to the carboxy-terminal region at the end of the long arm (Gehlsen, K. R., E. Engvall, K. Dickerson, W. S. Argraves, and E. Ruoslahti. 1989. J. Biol. Chem. 264:19034-19038; Tomaselli, K. J., D. E. Hall, L. T. Reichardt, L. A. Flier, K. R. Gehlsen, D. C. Turner, and S. Carbonetto. 1990. Neuron. 5:651-662). Using synthetic peptides, we have identified an amino acid sequence within the carboxy-terminal region of the laminin A chain that is recognized by the alpha 3 beta 1 integrin. The amino acid sequence represented by the synthetic peptide GD-6 (KQNCLSSRASFRGCVRNLRLSR residues numbered 3011 to 3032) of the globular domain of the murine A chain supports cell attachment and inhibits cell adhesion to laminin-coated surfaces. By affinity chromatography, peptide GD-6-Sepharose specifically bound solubilized alpha 3 beta 1 from extracts of surface-iodinated cells in a cation-dependent manner, while it did not bind other integrins. In addition, exogenous peptide GD-6 specifically eluted bound alpha 3 beta 1 from laminin-Sepharose columns but did not elute the alpha 3 beta 1 integrin from a fibronectin-Sepharose column. Using integrin subunit-specific monoclonal antibodies, only those antibodies against the alpha 3 and beta 1 subunits inhibited cell adhesion to peptide GD-6-coated surfaces. Finally, a polyclonal antibody made against peptide GD-6 reacted specifically with both murine and human laminin and significantly inhibited cell adhesion to laminin-coated surfaces but not those coated with other matrix proteins. These results identify the laminin A chain amino acid sequence of peptide GD-6 as representing a binding site in laminin for the alpha 3 beta 1 integrin.

Amino Acid Sequence↗
PubMed1992

Cell surface phosphatidylinositol-anchored heparan sulfate proteoglycan initiates mouse melanoma cell adhesion to a fibronectin-derived, heparin-binding synthetic peptide.

Cell surface heparan sulfate proteoglycan (HSPG) from metastatic mouse melanoma cells initiates cell adhesion to the synthetic peptide FN-C/H II, a heparin-binding peptide from the 33-kD A chain-derived fragment of fibronectin. Mouse melanoma cell adhesion to FN-C/H II was sensitive to soluble heparin and pretreatment of mouse melanoma cells with heparitinase. In contrast, cell adhesion to the fibronectin synthetic peptide CS1 is mediated through an alpha 4 beta 1 integrin and was resistant to heparin or heparitinase treatment. Mouse melanoma cell HSPG was metabolically labeled with [35S]sulfate and extracted with detergent. After HPLC-DEAE purification, 35S-HSPG eluted from a dissociative CL-4B column with a Kav approximately 0.45, while 35S-heparan sulfate (HS) chains eluted with a Kav approximately 0.62. The HSPG contained a major 63-kD core protein after heparitinase digestion. Polyclonal antibodies generated against HSPG purified from mouse melanoma cells grown in vivo also identified a 63-kD core protein. This HSPG is an integral plasma membrane component by virtue of its binding to Octyl Sepharose affinity columns and that anti-HSPG antibody staining exhibited a cell surface localization. The HSPG is anchored to the cell surface through phosphatidylinositol (PI) linkages, as evidenced in part by the ability of PI-specific phospholipase C to eliminate binding of the detergent-extracted HSPG to Octyl Sepharose. Furthermore, the mouse melanoma HSPG core protein could be metabolically labeled with 3H-ethanolamine. The involvement of mouse melanoma cell surface HSPG in cell adhesion to fibronectin was also demonstrated by the ability of anti-HSPG antibodies and anti-HSPG IgG Fab monomers to inhibit mouse melanoma cell adhesion to FN-C/H II. 35S-HSPG and 35S-HS bind to FN-C/H II affinity columns and require 0.25 M NaCl for elution. However, heparitinase-treated 125I-labeled HSPG failed to bind FN-C/H II, suggesting that HS, and not HSPG core protein, binds FN-C/H II. These data support the hypothesis that a phosphatidylinositol-anchored HSPG on mouse melanoma cells (MPIHP-63) initiates recognition to FN-C/H II, and implicate PI-associated signal transduction pathways in mediating melanoma cell adhesion to this defined ligand.

Amino Acid Sequence↗
PubMed1992

Coordinate role for cell surface chondroitin sulfate proteoglycan and alpha 4 beta 1 integrin in mediating melanoma cell adhesion to fibronectin.

Cellular recognition and adhesion to the extracellular matrix (ECM) has a complex molecular basis, involving both integrins and cell surface proteoglycans (PG). The current studies have used specific inhibitors of chondroitin sulfate proteoglycan (CSPG) synthesis along with anti-alpha 4 integrin subunit monoclonal antibodies to demonstrate that human melanoma cell adhesion to an A-chain derived, 33-kD carboxyl-terminal heparin binding fragment of human plasma fibronectin (FN) involves both cell surface CSPG and alpha 4 beta 1 integrin. A direct role for cell surface CSPG in mediating melanoma cell adhesion to this FN fragment was demonstrated by the identification of a cationic synthetic peptide, termed FN-C/H-III, within the fragment. FN-C/H-III is located close to the amino terminal end of the fragment, representing residues #1721-1736 of intact FN. FN-C/H-III binds CSPG directly, can inhibit CSPG binding to the fragment, and promotes melanoma cell adhesion by a CSPG-dependent, alpha 4 beta 1 integrin-independent mechanism. A scrambled version of FN-C/H-III does not inhibit CSPG binding or cell adhesion to the fragment or to FN-C/H-III, indicating that the primary sequence of FN-C/H-III is important for its biological properties. Previous studies have identified three other synthetic peptides from within this 33-kD FN fragment that promote cell adhesion by an arginyl-glycyl-aspartic acid (RGD) independent mechanism. Two of these synthetic peptides (FN-C/H-I and FN-C/H-II) bind heparin and promote cell adhesion, implicating cell surface PG in mediating cellular recognition of these two peptides. Additionally, a third synthetic peptide, CS1, is located in close proximity to FN-C/H-I and FN-C/H-II and it promotes cell adhesion by an alpha 4 beta 1 integrin-dependent mechanism. In contrast to FN-C/H-III, cellular recognition of these three peptides involved contributions from both CSPG and alpha 4 integrin subunits. Of particular importance are observations demonstrating that CS1-mediated melanoma cell adhesion could be inhibited by interfering with CSPG synthesis or expression. Since CS1 does not bind CSPG, the results suggest that CSPG may modify the function and/or activity of alpha 4 beta 1 integrin on the surface of human melanoma cells. Together, these results support a model in which the PG and integrin binding sites within the 33-kD fragment may act in concert to focus these two cell adhesion receptors into close proximity on the cell surface, thereby influencing initial cellular recognition events that contribute to melanoma cell adhesion on this fragment.

Amino Acid Sequence↗
PubMed1992

Rabbit corneal epithelial cells adhere to two distinct heparin-binding synthetic peptides derived from fibronectin.

Fibronectin plays an important role in corneal reepithelialization during corneal wound healing. In this study, rabbit corneal epithelial (RCE) cell adhesion to fibronectin was further defined using proteolytic fragments of fibronectin and chemically synthesized peptides derived from the amino acid sequence of fibronectin. RCE cells adhere to intact fibronectin, the 75 kD fragment containing the RGDS (Arg-Gly-Asp-Ser) cell adhesion-promoting sequence, and the 33/66 kD cell adhesion promoting/heparin-binding fragments of fibronectin. The 75 kD fragment and the 33/66 kD fragments partially inhibited RCE cell adhesion to intact fibronectin, suggesting that these fragments represent distinct sites used by RCE cells to adhere to intact fibronectin. Two chemically synthesized peptides derived from the amino acid sequence of the 33/66 kD fragments of fibronectin, FN-C/H-I (YEKPGSPPREVVPRPRPGV) and FN-C/H-III (YRVRVTPKEKTGPMKE), directly promoted the adhesion of RCE cells. As further evidence that FN-C/H-I and FN-C/H-III play a role in the adhesion of RCE cells to the 33/66 kD fragments of fibronectin, we have shown that soluble FN-C/H-I and FN-C/H-III inhibited RCE cell adhesion on surfaces coated with the 33/66 kD fragments. In addition, polyclonal IgG against FN-C/H-I and FN-C/H-III partially blocked RCE cell adhesion to the 33/66 kD fragments, confirming that these sequences represent adhesion-promoting sites within these fragments. In contrast, two previously described peptides from the 33/66 kD fragments of fibronectin, which promoted the adhesion of a variety of cell types, FN-C/H-II (KNNQKSEPLIGRKKT) and CS-1 (DELPQLVTLPHPNLHG-PEILDVPST), did not support RCE cell adhesion.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Central and peripheral neurite outgrowth differs in preference for heparin-binding versus integrin-binding sequences.

Neurons of the CNS and PNS differ in their response to fibronectin (FN) and proteolytic fragments of FN. The 33 kDa C-terminal cell and heparin-binding fragment of FN, in particular, is a strong promoter of CNS neurite outgrowth. To define further the neurite-promoting activity of the 33 kDa fragment, and to investigate further the differences between PNS and CNS responses to FN and the 33 kDa fragment, we contrasted neurite outgrowth by CNS and PNS neurons on three synthetic peptides representing sequences from this fragment of FN: two heparin-binding peptides, FN-C/H I and FN-C/H II (McCarthy et al., 1990), and an integrin-binding peptide, CS1 (Humphries et al., 1987). Spinal cord (SC) neurons, from the CNS, differed from dorsal root ganglion (DRG) neurons, from the PNS, with respect to substratum preference for heparin-binding versus integrin-binding peptides. SC neurite outgrowth was greatest on the heparin-binding peptide FN-C/H II, while DRG neurite outgrowth was greatest on the a4 beta 1 integrin-binding peptide CS1. To test whether the difference in substratum preference was due to differences in the molecular mechanism by which SC and DRG neurons interact with the 33 kDa fragment of FN, anti-beta 1 integrin antibodies and/or soluble heparin were added to the cultures as potential inhibitors of integrin-mediated or proteoglycan-mediated interactions with FN. SC neurite outgrowth was much more sensitive to the effect of heparin than anti-beta 1 integrin, indicating SC neurite outgrowth may involve predominantly a heparin-sensitive mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

A cell-surface heparan sulfate proteoglycan mediates neural cell adhesion and spreading on a defined sequence from the C-terminal cell and heparin binding domain of fibronectin, FN-C/H II.

FN-C/H II is a heparin binding synthetic peptide from the C-terminal cell and heparin binding domain of fibronectin (FN) that mediates neuronal cell adhesion, spreading, and neurite outgrowth. Cellular interactions with FN-C/H II are inhibited by soluble heparin, suggesting that a cell-surface proteoglycan may mediate interactions with FN-C/H II (Haugen et al., 1990). To test this hypothesis further, heparan sulfate (HS) or chondroitin sulfate (CS) was removed from the cell surface by enzyme treatment. Heparitinase but not chondroitinase treatment of cells inhibited rat B104 neuroblastoma cell adhesion and spreading on FN-C/H II. Additionally, heparitinase treatment decreased the spreading of cells on the 33/66 kDa fragments containing the C-terminal heparin binding domain of FN. Furthermore, antibodies generated against a mouse melanoma HS proteoglycan (HSPG) inhibited B104 cell adhesion to FN-C/H II and the 33/66 kDa FN fragments. 35S-HSPG isolated from B104 cells directly bound to FN-C/H II both in solid phase assays and by affinity chromatography, but failed to bind to a control peptide from this region, CS1. The binding of 35S-HSPG was predominantly mediated by the HS and not the core protein of the HSPG. SDS-PAGE of iodinated HSPG demonstrated a single 78 kDa core protein following heparitinase digestion, which migrated at 51 kDa under nonreducing conditions. Anti-HSPG antibodies recognized the 78 kDa core protein by immunoblotting, and stained the surface of rat B104 neuroblastoma cells and cells of the primary neonatal rat nervous system. These results identify a cell-surface HSPG that likely mediates neuronal cell binding interactions with FN-C/H II.

Amino Acid Sequence↗
PubMed1991

1H NMR and CD secondary structure analysis of cell adhesion promoting peptide F-9 from laminin.

A heparin binding, cell adhesion promoting domain, termed peptide F-9, from the B1 chain of human laminin, residues 641 to 660, i.e. RYVVLPRPVCFEKGMNYTVR, has been investigated by 1H NMR (500 MHz) spectroscopy and CD spectropolarimetry. While small linear peptides in water solution normally exist in a number of fluctuating conformational states, CD data analysis of peptide F9 indicates the existence of some preferred average structural populations consisting of about 30% beta-sheet, 22% beta-turn, and 6% alpha-helix. NMR structural analysis supports this observation and indicates specific sequences of preferred structural populations. Evidence for these is indicated by the presence of dNN nuclear Overhauser effect (NOE) populations and attenuated or absent d alpha N NOEs at short mixing times (0.1 s), 3J alpha N coupling constants of 5 and 10 Hz, and chemical shifts significantly removed from random coil positions. The NH2-terminal VVL sequence primarily exists in an extended chain conformation by virtue of large d alpha N NOEs and 9-10 Hz 3J alpha N coupling constants. Residues C10-N16 have turn-like or helix character with a run of dNN and d beta N NOEs and attenuated d alpha N NOEs. These midchain reversals include the lysine and asparagine residues proposed to be involved in heparin binding and N-glycosylation, respectively, to laminin peptide F-9.

Amino Acid Sequence↗
PubMed1991

The role of G-protein in matrix-mediated motility of highly and poorly invasive melanoma cells.

Membranes from 2 K1735 murine melanoma clones of high invasive capacity show increased amounts of pertussis toxin (PT) substrate when compared to a weakly invasive cellular counterpart. Using a panel of specific G-protein antibodies, we identified Gi alpha 2 as the PT-sensitive G-protein uniquely abundant in highly invasive cells. In addition, RNA hybridization results confirm the immunoblot observations that Gi alpha 2 is present at higher levels in strongly invasive cells. This result suggests that the elevated expression of Gi alpha 2 in highly invasive cells is not entirely due to differences in either translational efficiency or protein degradation but is related to altered RNA transcriptional initiation, processing and/or degradation. ADP-ribosylation of Gi alpha-subunits by PT inhibited the fibronectin, laminin and collagen type-IV-stimulated motility of the 2 highly invasive clones, while PT treatment of cells from a poorly invasive clone resulted in little or no reduction of the fibronectin, laminin or collagen type-IV-stimulated lower motility. Furthermore, PT treatment of highly or poorly invasive K1735 clones does not result in any alteration in cellular cAMP accumulation, suggesting that the PT substrate is not linked with the adenylyl cyclase enzyme complex. The data suggest that a PT-sensitive G-protein, probably Gi alpha 2 regulates second messenger pathways that contribute to elevated motility in highly invasive K1735 cells.

Adenylate Cyclase Toxin↗
PubMed1991

Localization of type IV collagen in the basement membranes of human prostate and lymph nodes by immunoperoxidase and immunoalkaline phosphatase.

The object of these studies was to examine the localization of type IV collagen (Coll-IV) in the basement membranes (BM) of epithelial and stromal elements (smooth muscle, nerves, vessels) in normal, hyperplastic, and neoplastic (primary and metastatic) prostate. We also examined the relationship of Coll-IV distribution to the degree of tumor differentiation (Gleason grading system). We compared immunoperoxidase (IP) and immunoalkaline phosphatase (AP) techniques in these studies and in selected samples we also evaluated immunofluorescence (IF) localization of Coll-IV and the effects of tissue fixation and pepsin digestion. We found that IF localization of Coll-IV was intense in unfixed sections. IP and AP reactions were absent in fixed, paraffin-embedded sections but pepsin treatment yielded intense and uniform reaction products in these same preparations. Both the IP and AP techniques showed similar localization of Coll-IV in the BM of normal, hyperplastic, and well-differentiated tumor. In most of the higher-grade tumors Coll-IV localization was reduced and a similar pattern of distribution was observed after IP and AP techniques. However, in some high-grade tumors the IP technique showed good localization but AP did not, and vice versa. Such discrepancies were noted in the BM of the tumor cells, as well as in the BM of the stromal elements and in lymph nodes with metastatic tumor. Thus, our study shows decreased Coll-IV localization in higher-grade tumors and suggests that the use of a single technique (IP or AP) may exaggerate this apparent loss of Coll-IV BM components. The exact cause of these discrepancies is unknown but they must reflect variable losses in the ability of the tumor cells to form BM, degradation or decreased synthesis of BM components by high-grade tumors, or a combination of the above.

Adenocarcinoma↗
PubMed1991

Synthetic peptides from the carboxy-terminal globular domain of the A chain of laminin: their ability to promote cell adhesion and neurite outgrowth, and interact with heparin and the beta 1 integrin subunit.

The large carboxy-terminal globular domain (G domain; residues 2,110-3,060) of the A chain of murine-derived laminin has been shown to promote heparin binding, cell adhesion, and neurite outgrowth. This study was conducted to define the potential sequence(s) originating from the G domain of laminin with any of these functional activities. A series of peptides were synthesized from the G domain, termed GD peptides, each approximately 20 amino acids long and containing multiple positively charged amino acids. In direct 3H-heparin binding assays, peptides GD-1 and GD-2 bound high levels of 3H-heparin, while peptides GD-3 and GD-4 bound lower levels of 3H-heparin, and GD-5 bound essentially no 3H-heparin. The binding of 3H-heparin to peptides GD-1 and GD-2 appeared to be of high affinity, since significant binding of 3H-heparin to these two peptides was still observed even when the NaCl concentration was raised to 1.0 M. Four of the peptides, GD-1, GD-2, GD-3, and GD-4, directly promoted the adhesion and spreading of HT-1080 human fibrosarcoma cells as well as the outgrowth of neurites from chick spinal cord and dorsal root ganglia neurons. In addition, solutions of these peptides or antibodies generated against these peptides inhibited laminin-mediated HT-1080 cell adhesion. Antibodies against the beta 1 integrin subunit inhibited HT-1080 cell adhesion and neurite outgrowth on surfaces adsorbed with peptides GD-3 and GD-4. Therefore, laminin appears to have multiple, independent sequences in the G domain that serve a similar cell adhesion promoting function for different cell types. Furthermore, these results suggest that the sequences comprising peptides GD-3 and GD-4 use an integrin as a receptor, of which the beta 1 integrin subunit is a component for these various cell types.

Amino Acid Sequence↗
PubMed1991

Effects of laminin on functional reinnervation of target organs by regenerating axons.

Reinnervation of sweat glands, skeletal muscle and skin was studied in the mouse paw after section of the sciatic nerve and repair by entubulation with collagen conduits, with and without a coating of laminin. After operation, sweat glands activated by pilocarpine reappeared at 32 days and increased in number to 67% of control counts. Muscle action potentials (during sciatic nerve stimulation) were recorded from the interosseus muscle at 39 days. The potential amplitudes increased to 30% of controls. The first withdrawal response from pin prick to the paw was observed at about 34 days, the response score increasing to 66% of control. There were no significant differences at any test interval between the control group and the group with laminin added.

Animals↗
PubMed1991

Human keratinocytes adhere to two distinct heparin-binding synthetic peptides derived from fibronectin.

Fibronectin is present at the dermal-epidermal junction in normal skin and is increased in skin tissues in inflammatory diseases, skin cancers, and wound repair. The present studies focused on further characterizing the interaction between fibronectin and keratinocytes, specifically addressing whether human keratinocytes utilize multiple adhesion promoting sequences within fibronectin. Initially, direct cell-binding assays were utilized in which keratinocyte adhesion to plastic substrata coated with fibronectin or proteolytic fragments of fibronectin was quantified. Intact fibronectin, a 75-kD proteolytic fragment containing the RGD sequence, and 33/66-kD cell adhesion/heparin binding fragments lacking the RGD sequence derived from the A and B chains of fibronectin, all promoted keratinocyte adhesion in a concentration-dependent manner. To further define putative cell-binding domains within the 33/66-kD fibronectin fragments, we studied three chemically synthesized peptides derived from the amino acid sequence of the 33-kD fragment of the fibronectin A chain: FN-C/H-I (YEKPGSPPREVVPRPRPGV), FN-C/H-II (KNNQKSEPLIGRKKT), and CS1 (DELPQLVTLPHPNLHGPEILDVPST). Substrata coated with either FN-C/H-I or FN-C/H-II promoted keratinocyte adhesion in a concentration-dependent and saturable manner, whereas peptide CS1 promoted no significant keratinocyte adhesion. In solution, both exogenous FN-C/H-I and FN-C/H-II partially inhibited keratinocyte adhesion to the 33/66-kD fibronectin fragments. Furthermore, antibodies prepared against these peptides also inhibited keratinocyte adhesion to the 33/66-kD fibronectin fragments. These data indicate that keratinocyte adhesion to fibronectin is mediated by multiple distinct amino acid sequences, at least two of which are localized to the carboxy-terminal heparin binding domain of fibronectin.

Antibodies↗
PubMed1991

An overview of role of matrix components.

The glomerular filtration barrier consists of complex matrix constituents interposed between the glomerular endothelial and epithelial cells, which constitute the lining of the glomerular capillaries. The matrix components include collagen and noncollagenous molecules such as laminin and proteoglycans. This review describes herein the metabolic consequences of diabetes mellitus to which increased permeability of the filtration barrier may be attributed by altering matrix molecules.

Animals↗
PubMed1991

Type IV collagen and corneal epithelial adhesion and migration. Effects of type IV collagen fragments and synthetic peptides on rabbit corneal epithelial cell adhesion and migration in vitro.

Type IV collagen, a 500-kilodalton (alpha 1)2(alpha 2)1 heterotrimer with noncollagenous domains (NC1) is the major molecule in most basement membranes in the body. In addition to its structural role as scaffolding, type IV collagen is involved in promoting adhesion and migration of various cell types in vitro, including rabbit corneal epithelial cells. This study assessed the effect of purified proteolytic fragments of type IV collagen and selected synthetic peptides derived from the alpha 1 and alpha 2 chains that are related to the adhesion and directed migration of dissociated primary cultured rabbit epithelial cells. Two homologous peptides (HEP-1 and HEP-2) derived from alpha 1 and alpha 2 NC1 regions were found to promote epithelial cell adhesion. A peptide (HEP-3) derived from an interruption of the triple helix of type IV collagen was effective in promoting corneal epithelial cell migration in both chemotaxis and haptotaxis assays. The helical fragment of type IV collagen promoted both directed migration and ample adhesion, indicating that there may be at least another moiety in the helical region responsible for cell adhesion. The results with these peptides revealed to some extent how corneal epithelial cells react at the molecular level with type IV collagen. They could serve as the basis for therapeutic agents to modify corneal epithelial behavior in situations of perturbed wound healing.

Amino Acid Sequence↗
PubMed1991

Tumor cell adhesive mechanisms and their relationship to metastasis.

Despite recent advances in the diagnosis and therapy of many forms of cancer, metastasis remains the major cause of death in cancer patients. As tumors progress they become increasingly heterogeneous, giving rise to aggressive subpopulations of tumor cells that subsequently invade local tissues, the lymphatics, and the circulatory system. This invasive behavior can ultimately lead to the widespread dissemination and metastasis of the primary tumor. In hematogenous metastasis, emboli consisting of tumor cells, host cells, platelets, and fibrin are transported to distant sites where they arrest in the microvasculature prior to extravasation. It is well accepted that tumor cell adhesion plays a fundamental role in many of the stages of the metastatic process. Tumor cell interactions with extracellular matrix components of tissue, tissue boundaries (basement membranes), or cell adhesion-promoting components of plasma; influence tumor cell motility, invasiveness, and many other important aspects of the metastatic tumor cell phenotype. Tumor cell adhesion also has a rate-limiting influence at various stages within the metastatic process, such as tumor cell arrest and extravasation. In addition, the ability of the immune system to recognize and successfully eradicated tumors is also highly dependent on the adhesion of activated lymphocytes to target tumor cells. Despite the rapid accumulation of information on the molecular basis of cell adhesion, our understanding of the relationship between tumor cell adhesion and hematogenous metastasis per se is fragmented and incomplete. Nevertheless, clear progress has been made, both in understanding the molecular basis of tumor cell adhesion and its relationship to the biology of tumor metastasis. New and exciting directions have been identified that are likely to yield direct benefits in developing new therapeutic or diagnostic approaches for malignant neoplasms. Our purpose is to briefly review the molecular basis of tumor cell adhesion from the standpoint of many of the receptors involved as well as their putative ligands. The relationship between specific tumor cell adhesion events and the formation of metastatic lesions is also addressed.

Animals↗
PubMed1990

Definition of a sequence, RYVVLPR, within laminin peptide F-9 that mediates metastatic fibrosarcoma cell adhesion and spreading.

A synthetic peptide from the inner globule of the B1 chain of laminin, termed peptide F-9 (RYVVLPRPVCFEKGMNYTVR; residues 641-660), has been shown to have heparin-binding and cell adhesion-promoting activities for diverse cell types (Charonis et al., J. Cell. Biol., 107: 1253-1260, 1988). In this study, the metastatic murine fibrosarcoma cell line, UV-2237-MM, adhered and spread on surfaces coated with laminin and peptide F-9 in a concentration- and time-dependent fashion. Cells migrated toward laminin in Boyden microchemotaxis chambers but not toward peptide F-9. However, exogenous soluble peptide F-9 inhibited both the adhesion and migration of cells toward laminin. Polyclonal antibodies raised against peptide F-9 were capable of inhibiting laminin-mediated cell adhesion and migration. Peptide F-9 is located 265 residues from CDPGYIGSR, another sequence on the B1 chain of laminin which has been reported by others to promote cell adhesion (Graft et al., Cell, 48: 989-996, 1987). In contrast to peptide F-9, various control peptides including CDPGYIGSR did not promote the adhesion, spreading, or migration of the UV-2237-MM fibrosarcoma cells. In addition, neither exogenous peptide CDPGYIGSR nor antibodies raised against peptide CDPGYIGSR were capable of inhibiting laminin-mediated cell adhesion or migration. These results indicate that peptide F-9, but not peptide CDPGYIGSR, represents a major fibrosarcoma cell adhesion-promoting domain on intact laminin. A series of overlapping peptides were synthesized which contained various portions of the parent peptide F-9. The use of these peptides in cell adhesion assays demonstrated that the sequence RYVVLPR from the amino terminus of peptide F-9 was essential for cell adhesion-promoting activity.

Amino Acid Sequence↗