Apoptosis Inducer for Cancer Cell

Abstract

The present invention revealed that by suppressing the expression of the WRN gene, the BLM gene, or the RecQ1 gene, which belong to the RecQ helicase family, apoptosis is induced in various cancer cells and their proliferation is suppressed. Compounds that suppress the expression of RecQ helicase family genes or the functions of RecQ helicase proteins are thought to have the activity of inducing apoptosis.

1 . An apoptosis inducer for cancer cells, wherein the apoptosis inducer comprises as an active ingredient a compound that suppresses the expression of a gene belonging to the RecQ DNA helicase family.  
     
     
         2 . The apoptosis inducer according to  claim 1 , wherein the compound that suppresses the expression of a gene belonging to the RecQ DNA helicase family is a double-stranded RNA having RNAi activity towards that RecQ DNA helicase family gene.  
     
     
         3 . The apoptosis inducer according to  claim 2 , wherein the double-stranded RNA comprises a sense RNA comprising a sequence homologous to an arbitrary 20 to 30 consecutive nucleotides from the mRNA of a gene belonging to the RecQ helicase family, and an antisense RNA, comprising the sequence complementary to the sense RNA.  
     
     
         4 . An apoptosis inducer for cancer cells, wherein the apoptosis inducer comprises as an active ingredient a DNA that can express the double-stranded RNA having RNAi activity towards a RecQ DNA helicase family gene.  
     
     
         5 . The apoptosis inducer according to  claim 1 , wherein the compound that suppresses the expression of a RecQ DNA helicase family gene is either: 
 (a) an antisense nucleic acid targeting a transcript of the gene belonging to the RecQ DNA helicase family, or a portion thereof; or    (b) a nucleic acid having the ribozyme activity of specifically cleaving a transcript of the RecQ DNA helicase family gene.    
     
     
         6 . An apoptosis inducer for cancer cells, which comprises as an active ingredient a compound that suppresses a function of a protein encoded by a RecQ DNA helicase family gene.  
     
     
         7 . The apoptosis inducer according to  claim 6 , wherein the compound that suppresses a function of a protein encoded by a gene belonging to the RecQ DNA helicase family is any one of: 
 (a) a mutant protein belonging to the RecQ DNA helicase family, where the mutant protein has a dominant-negative activity towards the protein encoded by the gene belonging to the RecQ DNA helicase family;    (b) an antibody that binds to the protein encoded by the gene belonging to the RecQ DNA helicase family; or    (c) a low-molecular-weight compound that binds to the protein encoded by the gene belonging to the RecQ DNA helicase family.    
     
     
         8 . The apoptosis inducer according to  claim 1 , wherein the gene belonging to the RecQ DNA helicase is the WRN gene, the BLM gene, or the RecQ1 gene.  
     
     
         9 . The apoptosis inducer according to  claim 1 , wherein the nucleotide sequence of the gene belonging to the RecQ DNA helicase family is the nucleotide sequence of any one of SEQ ID NOs: 6 to 30.  
     
     
         10 . The apoptosis inducer according to  claim 2 , wherein either strand of the double-stranded RNA with RNAi activity comprises the nucleotide sequence of any one of SEQ ID NOs: 1 to 5, 31 to 40, and 43 to 69.  
     
     
         11 . An anticancer agent which comprises the apoptosis inducer according to  claim 1 , as an active ingredient.  
     
     
         12 . A method of screening for a candidate compound for a cancer cell apoptosis inducer, which comprises the steps of: 
 (a) contacting a test compound with a protein encoded by a gene belonging to the RecQ DNA helicase family or a partial peptide thereof;    (b) assaying the binding activity between the protein, or the partial peptide thereof, and the test compound; and    (c) selecting a compound that binds to the protein encoded by the gene belonging to the RecQ DNA helicase family, or the partial peptide thereof.    
     
     
         13 . A method of screening for a candidate compound for a cancer cell apoptosis inducer, which comprises the steps of: 
 (a) contacting a test compound with cells expressing a gene belonging to the RecQ DNA helicase family or with an extract of those cells;    (b) determining the expression level of the gene belonging to the RecQ DNA helicase family; and    (c) selecting a compound that reduces the expression level by comparing the level with that determined in the absence of the test compound.    
     
     
         14 . A method of screening for a candidate compound for a cancer cell apoptosis inducer, which comprises the steps of: 
 (a) contacting a test compound with cells or an extract of those cells, wherein the cells have a DNA comprising a structure in which a reporter gene is operably linked to a transcriptional regulatory region of a gene belonging to the RecQ DNA helicase family;    (b) determining the expression level of the reporter gene; and    (c) selecting a compound that reduces the expression level by comparing the level with that determined in the absence of the test compound.    
     
     
         15 . A method of screening for a candidate compound for a cancer cell apoptosis inducer, which comprises the steps of: 
 (a) contacting a test compound with a protein encoded by a gene belonging to the RecQ DNA helicase family, or cells expressing that protein or an extract of those cells;    (b) determining the activity of the protein; and    (c) selecting a compound that reduces the activity of the protein by comparing the level with that determined in the absence of the test compound.    
     
     
         16 . The method according to  claim 12 , wherein the gene belonging to the RecQ DNA helicase family is the WRN gene, BLM gene, or RecQ1 gene.  
     
     
         17 . A method for producing the apoptosis inducer according to  claim 1  as a pharmaceutical composition, which comprises the steps of: 
 (a) contacting a test compound with a protein encoded by a gene belonging to the RecQ DNA helicase family or a partial peptide thereof;    (b) assaying the binding activity between the protein, or the partial peptide thereof and the test compound; and    (c) selecting a compound that binds to the protein encoded by the gene belonging to the RecQ DNA helicase family, or the partial peptide thereof;    (d) combining the compound with a pharmaceutically acceptable carrier.    
     
     
         18 . The apoptosis inducer according to  claim 4 , wherein the gene belonging to the RecQ DNA helicase is the WRN gene, the BLM gene, or the RecQ1 gene.  
     
     
         19 . The apoptosis inducer according to  claim 6 , wherein the gene belonging to the RecQ DNA helicase is the WRN gene, the BLM gene, or the RecQ1 gene.  
     
     
         20 . The apoptosis inducer according to  claim 4 , wherein the nucleotide sequence of the gene belonging to the RecQ DNA helicase family is the nucleotide sequence of any one of SEQ ID NOs: 6 to 30.  
     
     
         21 . The apoptosis inducer according to  claim 6 , wherein the nucleotide sequence of the gene belonging to the RecQ DNA helicase family is the nucleotide sequence of any one of SEQ ID NOs: 6 to 30.  
     
     
         22 . The apoptosis inducer according to  claim 4 , wherein either strand of the double-stranded RNA with RNAi activity comprises the nucleotide sequence of any one of SEQ ID NOs: 1 to 5, 31 to 40, and 43 to 69.  
     
     
         23 . The method according to  claim 13 , wherein the gene belonging to the RecQ DNA helicase family is the WRN gene, BLM gene, or RecQ1 gene.  
     
     
         24 . The method according to  claim 14 , wherein the gene belonging to the RecQ DNA helicase family is the WRN gene, BLM gene, or RecQ1 gene.  
     
     
         25 . The method according to  claim 15 , wherein the gene belonging to the RecQ DNA helicase family is the WRN gene, BLM gene, or RecQ1 gene.  
     
     
         26 . An anticancer agent which comprises the apoptosis inducer according to  claim 4 , as an active ingredient.  
     
     
         27 . An anticancer agent which comprises the apoptosis inducer according to  claim 6 , as an active ingredient.