Human-derived bradeion proteins, DNA coding for the proteins, and uses thereof

Abstract

A human-derived bradeion protein, which has the following properties: (i) it is a transmembranous protein; (ii) it has a structure characteristic of growth hormone and cytokine receptors even in a structure of its transmembranous portion when its structure is determined by a hydrophobicity analysis according to Kyte-Doolittle method; (iii) it is expressed at a high level in a human adult brain, and in less amount in the heart, while it is not expressed in other adult organs or fetus; (iv) it induces programmed cell death (apoptosis) when over-expressed in a cultured human nerve cell lines; (v) it induces termination of cell division and aging when over-expressed in a cultured human normal cell; (vi) it is located in cytoplasm, and forms an intracellular aggregate when overexpressed; and (vii) besides human adult neurons, it is specifically expressed in a human colorectal cancer cell line or in a skin cancer cell line, or an analogue thereof.

1 . A human-derived bradeion protein, which has the following properties: 
 (i) it is a transmembranous protein;    (ii) it has a structure characteristic of growth hormone and cytokine receptors even in a structure of its transmembranous portion when its structure is determined by a hydrophobicity analysis according to Kyte-Doolittle method;    (iii) it is expressed at a high level in a human adult brain, and in less amount in the heart, while it is not expressed in other adult organs or fetus;    (iv) it induces programmed cell death (apoptosis) when over-expressed in a cultured human nerve cell lines;    (v) it induces termination of cell division and aging when over-expressed in a cultured human normal cell;    (vi) it is located in cytoplasm, and forms an intracellular aggregate when overexpressed; and    (vii) besides human adult neurons, it is specifically expressed in a human colorectal cancer cell line or in a skin cancer cell line,    or an analogue thereof.    
     
     
         2 . The human-derived bradeion protein or an analogue thereof according to  claim 1 , wherein the programmed cell death (apoptosis) is induced when DNA coding for the bradeion protein or the analogue thereof is gene-transferred into a cultured cancer cell.  
     
     
         3 . The human-derived bradeion protein or an analogue thereof according to  claim 1 , comprising an amino acid sequence shown in SEQ ID NO: 2, or an amino acid sequence with deletions, substitutions or additions of at least one amino acid residue in the amino acid sequence shown in SEQ ID NO: 2.  
     
     
         4 . The human-derived bradeion protein or an analogue thereof according to  claim 1 , comprising an amino acid sequence shown in SEQ ID NO: 4, or an amino acid sequence with deletions, substitutions or additions of at least one amino acid residue in the amino acid sequence shown in SEQ ID NO: 4.  
     
     
         5 . DNA comprising a nucleotide sequence coding for the bradeion protein or the analogue thereof according to  claim 1 , or a fragment thereof.  
     
     
         6 . The DNA or a fragment thereof according to  claim 5 , comprising the nucleotide sequence 129-1943 of SEQ ID NO: 1, or a nucleotide sequence of at least 15 consecutive nucleotides derived from the nucleotide sequence 129-1943 of SEQ ID NO: 1.  
     
     
         7 . The DNA or a fragment thereof according to  claim 5 , comprising the nucleotide sequence 129-1562 of SEQ ID NO: 3, or a nucleotide sequence of at least 15 consecutive nucleotides derived from the nucleotide sequence 129-1562 of SEQ ID NO: 3.  
     
     
         8 . The DNA according to  claim 5 , which hybridizes with DNA comprising the nucleotide sequence 129-1943 of SEQ ID NO: 1 under stringent conditions.  
     
     
         9 . The DNA according to  claim 5 , which hybridizes with DNA comprising the nucleotide sequence 129-1562 of SEQ ID NO: 3 under stringent conditions.  
     
     
         10 . A vector comprising the isolated DNA according to  claim 17 .  
     
     
         11 . A host cell transformed or transfected with the vector of  claim 10 .  
     
     
         12 . A host cell according to  claim 11 , which is a prokaryotic or eukaryotic cell.  
     
     
         13 . An antibody immunologically reactive with the bradeion protein or the analogue thereof according to  claim 1 .  
     
     
         14 . A method for detecting a cancer, comprising detecting the cancer by using the DNA or the fragment thereof according to  claim 5  or the antibody according to  claim 13  as a tumor-specific marker.  
     
     
         15 . The method according to  claim 14 , wherein the cancer is human colorectal cancer or human malignant melanoma.  
     
     
         16 . The method according to  claim 14  or  15 , wherein the detection is conducted by hybridization or immunoassay.  
     
     
         17 . An isolated DNA that encodes a protein characterized by at least 90% homology with a human-derived bradeion a protein that (A) comprises an amino acid sequence of SEQ ID NO:2 and (B) has the following properties: 
 (i) it is a transmembranous protein;    (ii) it has a transmembrane portion, an extracellular portion, and a cytoplasmic portion in its molecule as determined by a hydrophobicity analysis according to Kyte-Doolittle method;    (iii) it is expressed in the human adult normal brain and heart; the expression level thereof in the heart being about 10% or lower of that in the brain, while it is not expressed in other adult organs or fetus;    (iv) it induces programmed cell death when over-expressed in a cultured human brain-derived undifferentiated nerve cell line;    (v) it induces termination of cell division and aging when overexpressed in a cultured human brain-derived differentiated nerve cell;    (vi) it is located in cytoplasm in the course of the induced cell death, and forms an intracellular aggregate when overexpressed; and    (vii) it is expressed in a human colorectal cancer cell line or in a human malignant melanoma cell line, but not in leukemia, lymphoma and lung carcinoma.