Extracellular matrix molecules are recognized by several integrin subtypes, making identification of cross-talk among different integrin subtypes difficult. Here, we evaluated the cross-talk of integrin subtypes using four different integrin-binding peptides (FIB1; integrin αvβ3/α5β1, A2G10; integrin α6β1, EF1zz; integrin α2β1, or 531; integrin α3β1) derived from extracellular matrix molecules. Various combinations of two different integrin-binding peptides were mixed and conjugated on a chitosan matrix at various molar ratios and were evaluated for cell attachment activity. FIB1/A2G10 (molar ratio 5:5; total 10 nmol/well)-chitosan matrix significantly enhanced cell attachment activity compared with sum of the cell attachment activity on FIB1 (5 nmol/well)-chitosan matrices and A2G10 (5 nmol/well)-chitosan matrices, respectively. However, none of the other peptides showed a significant activity change when they were mixed and conjugated on a chitosan matrix. We investigated the mechanisms of this enhancement. FIB1/A2G10 (8:2 or 6:4)-chitosan matrix increased the cell spreading, phosphorylation of focal adhesion kinase at Y397, and slightly decreased phosphorylation of caveolin-1 at Y14 in fibroblasts compared with FIB1-chitosan and A2G10-chitosan matrices. These results indicate that FIB1/A2G10 (8:2 or 6:4)-chitosan matrix synergistically enhances cell attachment, suggesting that integrins αvβ3/α5β1 and α6β1 are involved in a cross-talk and synergistically enhance cell attachment. These findings also suggest that the mixed peptide-chitosan matrix system can regulate the ratio of two different peptides and is useful for evaluating cellular functions through receptor-specific cross-talk. Further, FIB1/A2G10 (8:2 or 6:4)-chitosan matrix could be a useful material for tissue engineering.

In order to investigate the inhibitory effect and mechanism of recombinant polypeptide CH50 on invasion and metastasis of melanoma B16 cells, the recombinant polypeptide CH50 was separated and purified by ion exchange chromatographic technique. The melanoma B16 cells treated with purified CH50 were cultured in vitro, the number was counted at 4, 24, 48 and 72 h and their morphological changes were observed in order to detect their adhesion and spreading abilities. In in vivo study, the melanoma B16 cells were labeled with CFSE and treated with CH50 and then they were injected into mice via mouse-tail veins. After 5 h, the lung tissues were fixed by frozen section. Accumulation and invasion abilities of B16 cells on lung tissues were observed under the fluorescent microscopy. The results showed that the morphological character of B16 cells treated with CH50 changed greatly and the number of B16 cells treated with CH50 decreased significantly (P<0.05). The adhesion and spreading abilities of B16 cells treated with CH50 were weakened obviously and the metastasis foci on lung tissues reduced. It was concluded that the recombinant polypeptide CH50 inhibited invasion and metastasis of melanoma B16 cells on tissues and could be a prospective bio-product in tumor general therapy.

Fibronectin (FN) is a major matrix protein that is involved in multiple processes. Its Cell I-Hep II domain is potentially useful in tumor therapy. Here, a recombinant fragment of FN with the Cell I-Hep II-IIICS71 domain, CH/71, was expressed in Escherichia coli. The CH/71 fusion protein consists of Cell I-Hep II domain and 19th to 89th amino acids of IIICS domain of FN. The expression level of CH/71 in E. coli was very high after induction with IPTG. Furthermore, CH/71 protein was largely found in the soluble fraction. It was readily purified by one-step heparin-agarose affinity chromatograph. The ability of CH/71 binding cells was about 8-fold of that of Cell I-Hep II domain FN.

The sexually transmitted protozoan Trichomonas vaginalis cytoadheres to vaginal epithelial cells and causes contact-dependent cytotoxicity which, when combined with the normal exfoliation process, leads to erosion of the epithelium, which may allow trichomonads into extracellular matrix and basement membrane sites. Therefore, the association of T. vaginalis with immobilized fibronectin (FN) and laminin (LM) on cover-slips was examined. Binding of live parasites to coated cover-slips was time- and parasite-density-dependent. Coincubation with an inhibitor of trichomonad cysteine proteinases resulted in an increased attachment of parasites to FN but had no effect on binding to LM, denoting that protease activity influenced optimal FN associations. Further, 20 h mid-exponential phase trichomonads placed in fresh culture medium for 3 h gave higher levels of binding to FN, suggesting that changes during growth in vitro to T. vaginalis organisms affect maximal levels of binding to FN. Extended incubation with substrates diminished the capacity of parasites to bind FN and LM. Treatment of live organisms with periodate reduced binding to LM but not FN, suggesting a role for carbohydrates. In addition, trypsinization of live parasites decreased numbers bound to both substrates. Placement of trypsinized parasites in medium for 2 h fully regenerated binding to FN but not LM. Incubation of trypsinized parasites with cycloheximide abrogated regeneration of attachment to FN, affirming a role for synthesized surface proteins in FN binding. Importantly, the T. vaginalis adhesin proteins that mediate cytoadherence, and iron, a factor that regulates adhesin synthesis, were not involved in FN and LM recognition. These results suggest a role for surface proteins and carbohydrates in trichomonal associations with FN and LM, respectively.

On the basis of preparation of anti-metastatic recombinant FN polypeptides, CH50 and CH56, we further studied the function of these polypeptides. The capacity of CH50 binding with melanoma cells (ED50 30 mM) was higher than that of CH56 (ED50 45 mM). Both of the polypeptides could significantly suppress the binding of melanoma B16 cells to laminin. There was no significant difference in the inhibitory effect between two polypeptides. In the experimental metastasis of melanoma cells, both of CH50 and CH56 could significantly inhibit the metastasis of the tumor cells, and reduce the number of lung metastasis by about 80%. Our results suggest that III-11 and ED-A repeats influenced, to some extent, the binding capacity of bifunctional-domain polypeptide to cells, but did not affect the inhibition of the polypeptide on the metastasis of melanoma cells. The presence and connection of cell I and Hep II domains are the elements which determine the ability of recombinant FN polypeptides to inhibit the metastasis of tumor cells.

Two plasmids were constructed and used to express two triple-domain recombinant polypeptide of human fibronectin (FN). The cDNAs in plasmids code for two polypeptides, CH62 (Pro1239-Ser1515 of FN linked with Ala1690-Val2049 through Met) and CH63 (CH62 without Ile1850-Glu1978). The expression level of CH62 in E. coli was very low, but that of CH63 was very high. The results suggests that Asp1961-Glu1978 in FN is a key sequence influencing the expression of triple-domain polypeptide in E. Coli. After being dissolved and renatured, CH63 can be purified by heparin-agarose affinity chromatography. Both of the cell-binding domains in the recombinant polypeptide were functional. The production of CH63 provides a fundamental basis for further study of recombinant products with better anti-metastasis function.

The adhesive interaction between tumor cells and host cells or the extracellular matrix plays a crucial role in metastasis formation. Therefore, understanding the mechanism controlling metastasis may assist in the development of antimetastatic therapy. We have used synthetic or recombinant polypeptide analogues containing the Arg-Gly-Asp (RGD) sequence found in the functional domains of fibronectin, such as poly(RGD) or CH-271, to regulate the mechanisms involved in cell adhesion during the metastatic process. Poly(RGD) inhibited experimental lung and liver metastasis effectively when coinjected i.v. with various types of tumors. In a model of spontaneous lung metastasis using the B16-BL6 melanoma, repeated administration of this polypeptide before or after surgical excision of the primary tumor resulted in a significant inhibition of tumor metastasis without affecting the growth of the primary tumor and substantially prolonged the survival time of mice. The mechanism responsible for the inhibition of tumor metastasis by the polypeptides is at least partly associated with the ability to interfere with cellular functions such as adhesiveness, motility and invasiveness in the process of metastasis. Combined treatment of the CH-271 fusion polypeptide and anticancer drugs, i.e., anti-adhesion therapy combined with chemotherapy, caused a marked inhibition of lung and liver metastasis of tumors as compared with either treatment alone or with the control. In contrast, the promotion of tumor cell interaction with immune cells via cell adhesion molecules, which differs from the anti-adhesive mechanism, may lead to the induction of anti-tumor immune responses and, consequently, to the inhibition of tumor metastasis. The transfection of the gene of the B7-1 adhesion molecule into tumor cells (B16-BL6 or K1735-M2 melanoma) resulted in the remarkable reduction of lung metastasis caused by the i.v. injection into mice. Immunization of B7-transfected tumor was effective as a tumor vaccine for preventing the metastasis of B7 negative original tumor cells. Thus, the regulation of the adhesive interaction with tumor cells may provide a new and promising approach for the control and prevention of cancer metastasis.

Two expressing plasmids have been constructed and used to express two bifunctional-domain recombinant polypeptides of human fibronectin (FN) in E. coli. One was CH50 (Pro1239-Ser1515 of FN linked with Ala1690-Thr1960 of FN through Met) and the other was CH56 (Pro1239-Thr1960 of FN). Both of two polypeptides were capable of binding heparin and were purified by heparin-agarose affinity chromatography. The purified products were capable of binding cells. The production of CH50 and CH56 polypeptides provided a fundamental basis for further study of the anti-metastatic function of recombinant fibronectin polypeptides.

We used the Boyden chamber system to investigate the mechanism by which the antimetastatic agent sodium D-glucaro-delta-lactam (ND2001) inhibits tumor cell invasion, and by establishing what ND2001 did not achieve, we were able to pinpoint the areas in which it was successful as an inhibitor. ND2001 did not inhibit cell adhesion of a highly metastatic B16 melanoma variant (the B16 variant) to the reconstituted basal membrane Matrigel, nor did it affect the production or activity of basal membrane-degrading type i.v. collagenase, but, in the Boyden chamber, ND2001 inhibited cell migration of the B16 variant toward a chemoattractant, laminin, on the lower surface of a Matrigel-free filter set (haptotaxis). Lewis lung carcinoma (3LL) cells that had been treated with ND2001 also exhibited hardly any haptotaxis, although the cells showed no alteration in behavior during cell adhesion to Matrigel. Since ND2001 did succeed in inhibiting the pulmonary metastases of the B16 variant and 3LL, we infer that inhibition of the metastases by ND2001 in these tumors is likely to be due to the inhibition of haptotactic migration.

We have established eleven T cell hybridoma cell lines to investigate mechanisms controlling interaction of T lymphocytes with endothelial cells as well as extracellular matrix (ECM) proteins at the clonal level. T cell hybridomas were characterized and subdivided into four groups on the basis of their interaction behavior with high endothelial venules (HEV). Group 1 (G1) exhibited strong adhesiveness. The binding was temperature- and divalent cation-dependent. Group 2 exhibited both adhesiveness and transendothelial migration (TEM, i.e., transmigration beneath the cytoplasm of endothelial cells). Group 3 exhibited strong TEM. G2 and G3 hybridomas exhibited temperature-independent and divalent cation-independent binding to HEV. Group 4 exhibited nonspecific adhesiveness to the surface of a slide glass. BW 5147, a parent of T cell hybridomas, was classified as G4. TEM was dependent on both the nature of T cell hybridomas and endothelial cells. TEM was completely temperature-dependent. TEM of G3 hybridomas was not divalent cation-dependent. Each group of T cell hybridomas interacted with various ECM components.

1. Heparin is widely used in the treatment of thrombotic disorders and as an aid in surgery. Anti-inflammatory effects of heparin have also been described. In this study, we have investigated the effects of locally-injected heparin on the oedema formation and eosinophil accumulation induced by various inflammatory stimuli in guinea-pig skin. 2. Heparin dose-dependently suppressed the accumulation of 111In-labelled eosinophils induced by i.d. injection of zymosan-activated plasma (ZAP). The 111In-eosinophil accumulation induced by other inflammatory stimuli (compound 48/80, platelet activating factor, interleukin-8 and in a passive cutaneous anaphylaxis reaction) was also suppressed by locally-injected heparin. 3. Oedema formation in response to these same stimuli was not altered by the local injection of heparin. 4. Fucoidin, a negatively-charged sulphated algal polymer, had no effect on the 111In-eosinophil accumulation or oedema formation induced by ZAP. Nevertheless, fucoidin significantly suppressed the oedema formation induced by i.d. injection of cationic protein-containing extracts of Schistosoma mansoni larvae. Heparin also inhibited oedema induced by the extracts, suggesting that both fucoidin and heparin were effectively neutralizing the cationic protein of the extracts to inhibit their oedema-inducing activity. 5. Thus, heparin significantly inhibited the accumulation of 111In-eosinophils, but not oedema formation, induced by various inflammatory stimuli. This, taken together with the lack of effect of fucoidin, suggests that heparin interferes with the process of eosinophil trafficking by a mechanism that does not depend on neutralisation of the charge of the stimulatory molecules.