Inhibition of hepatic metastasis in mice treated with cell-binding domain of human fibronectin and angiogenesis inhibitor TNP-470.

BACKGROUND: To prevent tumor metastasis, we administered the cell-binding domain of fibronectin, in combination with the angiogenesis inhibitor TNP-470, to mice with hepatic metastasis. We then assessed the prevention of tumor metastasis resulting from the inhibition of adhesive interactions and the inhibition of angiogenesis. METHODS: A hepatic metastasis model was created by injecting 1 x 10(3) colon 26/TC-1 cells into the anterior mesenteric vein of CDF1 mice. The cell-binding domain obtained from fibronectin included the Arg-Gly-Asp (RGD) sequence. A fibronectin-binding domain (FND)-treated group, an FND plus TNP-470 group, and a control group were established. The animals were killed 4 weeks after the injections of the treatment agents had been completed and the number of metastatic liver nodules was counted. In a simultaneous experiment with the same design, the mice were not killed at 4 weeks, and their survival was observed. RESULTS: The mean number of nodules in the FND plus TNP-470 group was significantly lower than that in the control group (P = 0.019337). The inhibition rate was 51% in the FND group, 60% in the FND 10 micrograms plus TNP-470 10 mg/kg group, and 64% in the FND 10 micrograms plus TNP-470 100 mg/kg group compared with the control group. Mice from the FND group that were not killed died after 6-8 weeks, but mice from the FND plus TNP-470 group died after 8-12 weeks. CONCLUSION: The cell-binding domain of fibronectin may, potentially, be an effective form of antiadhesive therapy that competes with native adhesion molecules and blocks adhesion during the metastatic process. When the cell-binding domain of fibronectin is combined with TNP-470 to inhibit angiogenesis, more effective inhibition of metastatic tumor growth and prolongation of survival can be achieved than after treatment with the cell-binding domain alone.

Involvement of type VI collagen in interleukin-4-induced mineralization by human osteoblast-like cells in vitro.

We recently showed that interleukin-4 (IL-4) enhanced collagen and osteocalcin accumulation and caused mineralization in human periosteal osteoblast-like (SaM-1) cells. At that time, the expression of alpha1(VI) collagen mRNA was induced. In the present study, the possible role of IL-4-induced type VI collagen in the in vitro mineralization in osteoblasts was investigated. Addition of IL-4 in the early stage (for the first 10 days) was essential for the mineralization. The mRNA levels of alpha1(VI) and alpha2(VI) collagen and protein level of type VI collagen were transiently increased by IL-4 treatment up to day 5, whereas the alpha1(I) procollagen mRNA level was greater at day 10 than at day 5. Addition of anti-type VI collagen antibody remarkably reduced the extracellular accumulations of calcium and hydroxyproline induced by IL-4. Furthermore, the transfection of antisense oligonucleotides of alpha1(VI) to SaM-1 cells in the presence of IL-4 partially inhibited IL-4-induced type I collagen accumulation. These results demonstrated that type VI collagen played important roles for IL-4-induced mineralization and hydroxyproline accumulation mostly type I collagen accumulation, in human periosteal osteoblast-like cells.

Molecular cloning and characterization of mouse ficolin-A.

A novel ficolin-related gene was isolated from the mouse liver lambda ZAPII cDNA library. The protein encoded by this gene consists of both collagen- and fibrinogen-like domains, which are common features of the ficolin family, and was named mouse ficolin-A. The amino acid sequence of mouse ficolin-A is 60.2, 59.8, 59.8, and 59.6% identical to those of porcine ficolin-alpha, -beta, human ficolin-1, and EBP-37/P35, respectively. Northern blot analysis showed that mRNA of mouse ficolin-A is highly expressed in liver and spleen. Immunoblot analysis using an anti-mouse ficolin-A antiserum showed that mouse ficolin-A is a plasma protein with binding activity to elastin and GlcNAc.

Characterization of ficolins as novel elastin-binding proteins and molecular cloning of human ficolin-1.

A novel elastin-binding protein, EBP-37, was recently identified and purified from human plasma. Its partial amino acid sequences showed significant homology to porcine ficolins, which were originally purified from porcine uterus membranes as multimeric proteins with fibrinogen- and collagen-like domains. Here we report the presence of ficolins in an elastin-binding fraction of porcine plasma and the direct binding of recombinant porcine ficolin-alpha to elastin. In addition, a cDNA encoding a human counterpart of porcine ficolins that is composed of 319 amino acids and is different from EBP-37 was cloned and named human ficolin-1. Northern blotting of various human tissues revealed that human ficolin-1 mRNA is highly expressed in peripheral blood leukocytes. These data suggested that there are at least two kinds of ficolin-related proteins in both pig and human, and they may function as plasma proteins with elastin-binding activities.

EBP-37, a new elastin-binding protein in human plasma: structural similarity to ficolins, transforming growth factor-beta 1-binding proteins.

In order to study the elastin-binding factors in blood, human plasma was applied to an alpha-elastin-Sepharose column. The column-binding fraction contained a 37-kDa protein, which was tentatively named EBP-37. Partial amino acid sequences of EBP-37 were determined. It had collagenous and non-collagenous domains. Homology searches of the sequences revealed that the protein is very similar but not identical to ficolins, transforming growth factor-beta 1 (TGF-beta 1)-binding proteins from porcine uterus membranes. Direct interaction of EBP-37 with elastin was confirmed by demonstrating the binding of the isolated EBP-37 to alpha-elastin on a nitrocellulose membrane using the EBP-37-specific antiserum. The existence of oligomers and multimers crosslinked by disulfide bonds was demonstrated by immunoblot analysis. Possible functions of EBP-37 are discussed.

Interaction of human plasma fibronectin with alpha-elastin.

Because there are contradictory reports about the interaction of plasma fibronectin with elastin, we investigated the interaction in vitro. When human plasma was applied to an alpha-elastin-Sepharose column at 4 degrees C, the column-binding fraction contained fibronectin. When isolated plasma fibronectin was applied to the same column at 4 degrees C, most of the fibronectin bound to the column and was eluted with 1 M KBr. However, the binding affinity of plasma fibronectin to the alpha-elastin-Sepharose column was much weaker at 25 degrees C than at 4 degrees C. The elastin-plasma fibronectin interaction was further confirmed by demonstrating the binding of alpha-elastin to fibronectin on polyvinylidene difluoride membranes using an alpha-elastin specific antibody. The elevation of the surface hydrophobicity of plasma fibronectin at 4 degrees C was observed by hydrophobic chromatography, using alkyl-Sepharose columns. It seems that the binding of plasma fibronectin to alpha-elastin involves hydrophobic interaction, which is affected by temperature and possibly by other factors.