ING-encoded p33ING1 protein as a mediator of p53 signaling pathway in mammalian cells

Abstract

The invention relates to a novel tumor suppressor gene, termed ING, genetic suppressor elements derived from this gene, and the protein produced by expression of this gene, known as p33 ING1 . The invention provides methods for characterizing mammalian cells on the basis of whether such cells express the ING gene, and embodiments of such methods directed at malignant or pre-malignant tissues in an animal for assaying the risk of developing malignant disease by the animal.

We claim:  
     
         1 . An isolated nucleic acid encoding an amino acid sequence of a mammalian ING1 gene product identified by SEQ ID No. 7.  
     
     
         2 . A recombinant expression construct comprising a nucleic acid according to  claim 1 .  
     
     
         3 . A eukaryotic cell transformed with the recombinant expression construct of  claim 2 .  
     
     
         4 . A homogeneous composition of a 26 kilodalton ING1 gene product having an amino acid sequence identified as SEQ ID No. 7.  
     
     
         5 . A method of enhancing transcriptional activator activity of p53 in a mammalian cell expressing p53, the method comprising the step of introducing into the cell a recombinant expression construct according to  claim 2 .  
     
     
         6 . A method of diagnosing a malignant or premalignant condition in a human, the method comprising the steps of: 
 a) obtaining a cell or tissue sample from the human;    b) assaying the sample to determine ING1 gene expression in the sample;    c) comparing ING1 gene expression in the sample with ING1 gene expression in a nonmalignant human cells or tissue;    wherein a malignant or premalignant condition is diagnosed when ING1 gene expression in the sample is less than ING1 gene expression in the nonmalignant human cells or tissues.    
     
     
         7 . The method of  claim 6 , further comprising the steps of: 
 d) assaying the sample to determine p53 gene expression in the sample;    wherein a malignant or premalignant condition is diagnosed when both p53 and ING1 gene expression in the sample is less than p53 or ING1 gene expression in the nonmalignant human cells or tissues.    
     
     
         8 . The method of  claim 6 , wherein the malignant condition is gastric cancer, breast cancer, brain cancer, or head or neck squamous cell carcinoma.  
     
     
         9 . A method of screening a human sample to detect a malignant or premalignant condition, the method comprising the steps of: 
 a) obtaining a cell or tissue sample from the human;    b) assaying the sample to determine ING1 gene expression in the sample;    c) comparing ING1 gene expression in the sample with ING1 gene expression in a nonmalignant human cells or tissue;    wherein a malignant or premalignant condition is detected when ING1 gene expression in the sample is less than ING1 gene expression in the nonmalignant human cells or tissues.    
     
     
         10 . The method of  claim 9 , further comprising the steps of: 
 d) assaying the sample to determine p53 gene expression in the sample;    wherein a malignant or premalignant condition is detected when both p53 and ING1 gene expression in the sample is less than p53 or ING1 gene expression in the nonmalignant human cells or tissues.    
     
     
         11 . The method of  claim 9 , wherein the malignant condition is gastric cancer, breast cancer, brain cancer, or head or neck squamous cell carcinoma.  
     
     
         12 . A method of assessing a human sample to determine a risk of developing a malignant or premalignant condition, the method comprising the steps of: 
 a) obtaining a cell or tissue sample from the human;    b) assaying the sample to determine ING1 gene expression in the sample;    c) comparing ING1 gene expression in the sample with ING1 gene expression in a nonmalignant human cells or tissue;    wherein a risk for developing a malignant or premalignant condition is determined to exist when ING1 gene expression in the sample is less than ING1 gene expression in the nonmalignant human cells or tissues.    
     
     
         13 . The method of  claim 12 , further comprising the steps of: 
 d) assaying the sample to determine p53 gene expression in the sample;    wherein a risk for developing a malignant or premalignant condition is determined to exist when both p53 and ING1 gene expression in the sample is less than p53 or ING1 gene expression in the nonmalignant human cells or tissues.    
     
     
         14 . The method of  claim 12 , wherein the malignant condition is gastric cancer, breast cancer, brain cancer, or head or neck squamous cell carcinoma.  
     
     
         15 . A genetic suppressor element encoding an antisense RNA having a nucleotide sequence identified as SEQ ID No. 1.  
     
     
         16 . A recombinant expression construct encoding a genetic suppressor element according to  claim 15 .  
     
     
         17 . A mammalian cell transformed with the recombinant expression construct of  claim 16  wherein the genetic suppressor element is expressed in the cell.  
     
     
         18 . A method for facilitating anchorage independent growth in a mammalian cell, the method comprising the step of introducing the genetic suppressor element of  claim 15  into the cell.  
     
     
         19 . A method for protecting a mammalian cell from radiation or cytotoxic drugs, the method comprising the step of introducing the genetic suppressor element of  claim 15  into the cell.  
     
     
         20 . A method for inhibiting p53-mediated transcription of a gene in a mammalian cell that expresses p53, the method comprising the step of introducing the genetic suppressor element of  claim 15  into the cell.  
     
     
         21 . A method for activating p53-mediated transcription of a gene in a mammalian cell that expresses p53, the method comprising the step of introducing a recombinant expression construct encoding ING1 into the cell.  
     
     
         22 . A diagnostic assay comprising the steps of 
 (a) isolating cellular RNA comprising messenger RNA from a tumor or malignant cells from an animal;    (b) measuring a level of expression of a ING1 gene in the tumor or malignant cells in the animal;    (c) determining whether the level of expression of the ING1 gene in the tumor or malignant cells indicates that the ING1 gene is under-expressed in the tumor or malignant cells in the animal.    
     
     
         23 . A diagnostic assay comprising the steps of 
 (a) isolating cellular protein from a tumor or malignant cells from an animal;    (b) measuring an amount of ING1 protein in the tumor or malignant cells in the animal;    (c) determining whether the amount of ING1 protein in the tumor or malignant cells indicates that the ING1 protein is under-expressed in the tumor or malignant cells in the animal.