Inhibitory effect of antimetastatic fusion polypeptide of human fibronectin on tumor cell adhesion to extracellular matrices

Inhibitory effect of recombinant fibronectin polypeptide CH50 on invasion and metastasis of melanoma B16 cells

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.

Inhibition of adhesion, invasion, and metastasis by antibodies targeting CEACAM6 (NCA-90) and CEACAM5 (Carcinoembryonic Antigen)

CEACAM5 and CEACAM6 are overexpressed in many cancers and are associated with adhesion and invasion. The effects of three monoclonal antibodies targeting different epitopes on these antigens (NH2-terminal [MN-3] and A1B1 domains [MN-15] shared by CEACAM5 and CEACAM6 and the A3B3 domain [MN-14] restricted to CEACAM5) were evaluated in migration, invasion, and adhesion assays in vitro using a panel of human pancreatic, breast, and colonic cancer cell lines, and in the GW-39 human colonic micrometastasis model in vivo. MN-3 Fab' and MN-15 Fab' were both effective at inhibiting cell migration. MN-15 Fab' treatment inhibited invasion, reducing cell penetration through an extracellular matrix (ECM). MN-3 Fab' also decreased invasion but was less effective than MN-15 Fab' in four of five cell lines. All three monoclonal antibody (mAb) Fabs decreased adhesion of tumor cells to endothelial cells by 49% to 58%. MN-15 Fab' but not MN-3 or MN-14 Fabs induced a decrease in adhesion of three of six cell lines to the ECM protein, fibronectin, but adhesion to vitronectin, laminin, collagen-I, and collagen-IV was not affected. In vivo studies showed that treatment with MN-3 Fab' or MN-15 Fab' of mice implanted with GW-39 human colonic cancer cells increased their survival (P < 0.025 and P < 0.01, respectively). These studies show that antibody Fabs that target either CEACAM5 or CEACAM6 affect cell migration, cell invasion, and cell adhesion in vitro, and that MN-15 and MN-3 Fabs have antimetastatic effects in vivo, resulting in improved survival of mice with metastases. Thus, blocking the N and A1B1 domains of CEACAM5/CEACAM6 can impede the metastatic process.

Cell adhesion molecules and cancer metastasis

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.

Construction of expressing plasmids of recombinant FN polypeptides with bifunctional-domain and the characterization of the products expressed in E. coli

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.

Inhibitory effect of recombinant fibronectin polypeptides on the adhesion of liver-metastatic lymphoma cells to hepatic sinusoidal endothelial cells and tumor invasion

We have investigated the inhibitory mechanism of the initial arrest of L5178Y-ML25 lymphoma cells in a target organ (liver) by using recombinant fibronectin fragments with cell- and/or heparin-binding domains (C-274, H-271 or the fusion fragment CH-271). Pretreatment of hepatic sinusoidal endothelial (HSE) cell monolayers with lymphoma cells or their conditioned medium for 4 to 6 h resulted in the enhancement of lymphoma cell adhesion to HSE cell monolayer. The increased tumor adhesiveness was completely abolished by preincubation of the conditioned medium with anti interleukin-1 beta monoclonal antibody (mAb). Synthetic sialyl Le(x) (SLe(x)) as a ligand for endothelial cell leukocyte adhesion molecule-1 (ELAM-1) adhesion receptor and anti ELAM-1 mAb blocked the conditioned medium-induced enhancement of tumor-endothelial cell interaction, while pretreatment of the activated HSE cell monolayer with anti vascular cell adhesion molecule-1 (VCAM-1) mAb did not affect the enhanced tumor cell adhesion. These results indicate that tumor cell interaction with the stimulated HSE cells is mediated by ELAM-1 molecules on HSE cells. However, the expression of SLe(x) and SLe(a) on the tumor surface was not observed by flow cytometric analysis. ELAM-1-mediated enhancement of tumor cell adhesion to HSE monolayer was also inhibited in a concentration-dependent manner by CH-271 fusion polypeptide or the sulfated chitin derivative sulfated carboxymethyl-chitin, which can bind to the heparin-binding domain of CH-271. In addition, CH-271 inhibited not only tumor-endothelium interaction but also tumor cell invasion into reconstituted basement membrane Matrigel in vitro.

Functional analysis of mononuclear cells infiltrating into tumors: establishment of T cell hybridomas exhibiting distinct interacting abilities with endothelial cells and extracellular matrix components

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.

Inhibition of tumor metastasis by Arg-Gly-Asp-Ser (RGDS) peptide conjugated with sulfated chitin derivative, SCM-chitin-RGDS

We have synthesized a new compound in which Arg-Gly-Asp-Ser (RGDS) was conjugated with 6-O-sulfated and 6-O-carboxymethyl-chitin (SCM-chitin), i.e. SCM-chitin-RGDS, and tested the inhibitory effect on lung and liver metastases of three different types of tumors in mice. SCM-chitin-RGDS was more effective for the inhibition of liver metastasis of L5178Y-ML25 lymphoma and lung metastases of colon 26 M3.1 cells than SCM-chitin, RGDS or their mixture. GRGDS peptide, however, required a higher dose (3000 micrograms) to obtain a sufficiently antimetastatic effect. Intermittent i.v. administration of SCM-chitin-RGDS before or after the i.v. inoculation of L5178Y-ML25 cells caused significant inhibition of liver metastasis as compared with the multiple administration of RGDS, SCM-chitin or untreated control. Co-injection of lymphoma cells with SCM-chitin-RGDS or multiple treatment of SCM-chitin-RGDS after tumor inoculation showed significantly enhanced survival rate. SCM-chitin-RGDS also showed the spontaneous lung metastasis produced by intrafootpad injection of B16-BL6 melanoma cells by the multiple i.v. administrations. These results demonstrate that the conjugation of RGDS peptide with SCM-chitin led to augmentation of therapeutic potential to cancer metastasis, thus implying an importance of the conjugation of cell-adhesive RGDS peptide with structurally heparin-like SCM-chitin, which possess binding ability to the heparin-binding domain of fibronectin or laminin and extremely low anticoagulant properties.

Antimetastatic effect by anti-adhesion therapy with cell-adhesive peptide of fibronectin in combination with anticancer drugs

We have investigated the therapeutic effect of CH-271 fusion polypeptide containing both cell-binding domain (C-274) and heparin-binding domain (H-271) of fibronectin in combination with anticancer drugs such as doxorubicin (DOX) or mitomycin C (MMC) on tumor metastasis of different types of tumors. CH-271 fusion polypeptide alone significantly inhibited both liver and lung metastasis when it was co-injected with L5178Y-ML25 T-lymphoma, RAW117-H10 B-lymphoma or B16-BL6 melanoma cells, and spontaneous lung metastasis of B16-BL6 melanoma cells when administered i.v. seven times before or after surgical excision of the primary tumors. Combined treatments with CH-271 and either DOX or MMC significantly inhibited liver and lung metastasis of lymphoma or melanoma cells respectively, as compared with either treatment alone or the untreated control. Administrations of CH-271 and DOX in combination substantially prolonged the survival time of mice injected i.v. with L5178Y-ML25 cells. CH-271 or DOX was effective for inhibiting the invasion of L5178Y-ML25 cells into Matrigel in a concentration-dependent manner. Our previous study has shown that CH-271-mediated inhibition of tumor invasion may be due in part to the anti-cell adhesive property without affecting the cell growth, whereas the anti-invasive effect of DOX was established to have resulted from the growth inhibition of tumor cells. Moreover, the combination of CH-271 with DOX provided a more effective inhibition of tumor invasion into Matrigel than did either alone. Thus, we have demonstrated that the combination of anti-cell adhesive CH-271 and anticancer drugs such as DOX or MMC, i.e. anti-adhesion therapy and chemotherapy, is a new approach that offers enhanced (additive) inhibitory effects on tumor metastasis and invasion.

Recombinant fusion polypeptide with cell- and heparin-binding domains of fibronectin inhibits liver metastasis of L5178Y-ML25 lymphoma cells

We have investigated the effect of recombinant polypeptides with cell-binding domain (C-274) or with heparin-binding domain (H-271) and their fusion polypeptide (CH-271) on liver metastasis of murine lymphoid tumor. The polypeptides containing heparin-binding domain, H-271 and CH-271, were able to inhibit liver metastasis when co-injected i.v. with L5178Y-ML25 T-lymphoma cells, while C-274 with cell-binding domain showed much weaker antimetastatic activity. Treatment with H-271 or CH-271 substantially prolonged the survival time of mice injected i.v. with L5178Y-ML25 cells. CH-271, containing cell- and heparin-binding domains, was more antimetastatic than H-271. The reason why CH-271 was more effective in inhibiting liver metastasis than H-271 can not be explained in terms of a difference in the stability in the circulation or in the molecular size of the polypeptide. The polypeptides used in this study did not affect the tumor cell growth or viability in vitro. CH-271 was found to be still active in inhibiting liver metastasis even when natural killer cells or macrophages were removed from this system. Furthermore, multiple administrations of CH-271 after tumor implantation effectively inhibited liver metastasis and enhanced the survival rate as compared with H-271, C-274 and untreated control. Thus, the fusion of H-271 with C-274 (i.e. CH-271) augments the antimetastatic property of H-271, possibly through the interaction between tumor cells and the heparin-binding domain of fibronectin.