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

High-level expression of a recombinant fragment of human fibronectin containing the Cell I-Hep II-IIICS71 domain in Escherichia coli as a soluble protein

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.

Comparative study on the inhibitory effect of recombinant FN polypeptide CH50 and CH56 on the metastasis of melanoma cells

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.

Augmentation of recombinant fibronectin polypeptide CH50 on the antitumor function of macrophages

We prepared an anti-metastatic polypeptide, recombinant fibronectin polypeptide CH50, and finished the preliminary identification of its functions. In this paper, we studied the effect of this polypeptide on the function of macrophages. CH50 can significantly augment the production of nitric oxide(NO) by macrophages in a dose-dependent manner. The continuous presence of CH50 had a much stronger effect. In the presence of CH50, the cytotoxicity of macrophages to melanoma B16/F1 cells was significantly enhanced, and a stronger effect was obtained if CH50 was present continuously. CH50 polypeptide and IFN-gamma have a synergistic effect on the production of NO by macrophages and the cytotoxicity of macrophages on tumor cells. In the in vivo experiments, CH50 can inhibit the growth of tumor cells, and have a better effect in the presence of IFN-gamma. Our results suggest that recombinant fibronectin polypeptide CH50 has two functions: one is to inhibit the metastasis of tumor cells, and the other one is to augment the function of macrophages. And this polypeptide will be potentially useful in tumor therapy.

Effect of fragment Asp1961-Glu1978 in fibronectin on the expression of triple-domain polypeptide in E. coli

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.