Expression Of Human Monocyte Chemotactic Protein-1 (MCP-1) In E. Coli And Research Of Its Biological Activity

Tumor — associated macrophages (TAM) may play an important role in growth , metastasis and prognosis of malignant neoplasms. In recent study it had been identified that the infiltration of TAM in the tumor had close relationship with the secreted chemotactic factors by tumor cells. Monocyte chemotactic protein 1 (MCP—1) is one of the chief components of tumor—derived chemoattrac-tants to induce the migration and recruitment of monosytes. It may also have some tumoricidal functions by activating macrophages. In our research a fusion protein vector,pGEX—4T—MCP,was constructed by inserting the cDNA of human MCP—1 gene into the multi — clonal site of the plasmid pGEX —4T—1. Then the recombinant plasmid was transduced into the E. coli. JM109 to express a fusion protein GST —MCP —1. After the purification of the recombinant protein through a Glutathione — Sepharose 4B affinity chromatography column, its chemotactic activity to monocyte was assayed with a 48 — well micro — chemo-taxis device. We established a tumor-bearing nude mouse model of stomach cancer by innoculating SGC7901 cells subcutaneously to observe the tumor growth rate after local injection of purified MCP—1 around the tumor. The infiltration of the macrophages was estimated histologically in the tumor. The results indicated that the E. coli. JM109 which contained the recombinant plasmid pGEX —4T — MCP could express a fusion protein GST—MCP—1 upto 31. 6% of total bacterial products after IPTG induction. The product purified by affinity—chroma tog-...