Chemistry: natural resins or derivatives; peptides or proteins; – Proteins – i.e. – more than 100 amino acid residues – Lymphokines – e.g. – interferons – interlukins – etc.
Patent
1989-01-24
1992-03-10
Draper, Garnette D.
Chemistry: natural resins or derivatives; peptides or proteins;
Proteins, i.e., more than 100 amino acid residues
Lymphokines, e.g., interferons, interlukins, etc.
435 697, 4353201, 43525233, 536 27, 530350, C07K 1512, C12N 1519, C12N 1503
Patent
active
050950967
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a fused protein comprising a polypeptide containing an antibody binding site of protein A and a polypeptide of lymphotoxin, DNA coding for the fused protein, plasmids containing the DNA, Escherichia coli transformed with the plasmid, and a process for production of the fused protein using the E. coli.
BACKGROUND ART
Recently, studies have been made of targeting therapy, wherein a monoclonal antibody specific to cancer cells is linked to a anticancer substance to focus the anticancer substance onto the cancer tissue using the specificity of the monoclonal antibody.
Although, as anticancer substances used in such an approach, a plant toxin ricin, diphtheria toxin and the like have been studied, the use of lymphotoxin as a anticancer substance for the targeting therapy has not been attempted.
As methods of linking a cancer-specific antibody and an anticancer substance wherein they are directly covalently linked, a method wherein a liposome encapsulating an anticancer substance is linked to a cancer-specific antibody, and the like, is known.
Nevertheless, an attempt wherein an affinity of protein A to an antibody is used to link a cancer-specific antibody and an anticancer substance for the targeting therapy has not been made.
Although it is already known to prepare a fused protein comprising protein A and a physiologically active peptide (WO 84/03103), this approach is mainly directed to an affinity purification of the physiologically active peptide and the preparation of an antigen for immunization.
A conventional approach wherein an anticancer substance is chemically linked to a cancer-specific antibody for the targeting therapy is disadvantageous in that it is difficult to make the anticancer substance enter cancer cells. Conversely, it is known that lymphotoxin selectively and directly kills cancer cells via receptors on a surface of the cancer cell. Accordingly, the present invention is intended to provide a means of an effective cancer therapy such as a targeting therapy using lymphotoxin having such an advantageous property.
DISCLOSURE OF THE INVENTION
To attain the above-mentioned object, the present invention provides a fused protein comprising a polypeptide containing an antibody binding site of protein A and a polypeptide of lymphotoxin, and having both a biological activity originally exhibited by the lymphotoxin, i.e., anticancer action, and an ability to bind to the antibody originally exhibited by protein A; as well as a process for production of the fused protein, and DNA coding for the fused protein necessary for that production process, plasmids containing the DNA and E. coli transformed with the plasmid.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the construction of plasmid pLTM1;
FIG. 2 shows the construction of plasmid pLTM2;
FIGS. 3-1 and 3-2 show a nucleotide sequence of DNA coding for a native lymphotoxin in a starting plasmid pLTM2 for the construction of plasmids of the present invention, and an amino acid sequence of a corresponding polypeptide;
FIGS. 4-1 and 4-2 show a part relating to the present invention of a nucleotide sequence of DNA coding for protein A in plasmid pRIT2T, and an amino acid sequence of a corresponding polypeptide;
FIG. 5 shows the construction of plasmid pLTM9;
FIG. 6 shows the construction of plasmid pPRALT1 of the present invention; and,
FIG. 7 shows a nucleotide sequence at a junction of the present fused protein and a corresponding amino acid sequence.
BEST MODE OF CARRYING OUT THE INVENTION
Since the present fused protein exhibits an anticancer action at the lymphotoxin protein thereof and has an ability to bind to an antibody at the protein A portion thereof due to its affinity therewith, the fused protein can bond to an antibody specific to a cancer, for example, a monoclonal antibody, to form a complex. Therefore, when such a complex is parenterally administered, it is expected to concentrate at cancer cells, where the fused protein is given to the cancer cells by the affinity between ly
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Kato Seishi
Miki Tetsuzo
Osada Hiroshi
Central Glass Company Ltd.
Draper Garnette D.
Furman Keith C.
Hodogaya Chemical Co. Ltd.
Nippon Soda Company Ltd.
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