Novel human p53 splice variant displaying differential transcriptional activity

Abstract

Novel human p53 splice variant displaying differential transcriptional activity Described is a nucleic acid molecule encoding a p53 variant characterized in that it is capable of transactivating the p21- and 14-3-3σ-promoter but not the mdm2-, bax- and PIG3-promoter. Preferably, in said p53 variant exon 7, exon 8 and/or exon 9 are partially or entirely deleted. Finally, means for inhibiting the activity of this p53 variant are described which are useful for the therapy of cancer.

1 . A nucleic acid molecule encoding a p53 variant characterized in that it is capable of transactivating the p21- and 14-3-3σ-promoter but not the mdm2-, bax- and PIG3-promoter. 
     
     
         2 . The nucleic acid molecule of  claim 1 , wherein the nucleotide acid encoding the p53 variant is characterized in that exon 7, exon 8 and/or exon 9 are partially or entirely are deleted. 
     
     
         3 . The nucleic acid molecule of  claim 1  wherein the p53 variant comprises the amino acid sequence SEQ ID NO: 24 or an amino acid sequence having at least 90% homology to SEQ ID NO: 24 and is capable of transactivating the p21- and 14-3-3σ-promoter but not the mdm2-, bax- and PIG3-promoter. 
     
     
         4 . An isolated p53 variant characterized in that it is capable of transactivating the p21- and 14-3-3σ-promoter but not the mdm2-, bax- and PIG3-promoter. 
     
     
         5 . The isolated p53 variant according to  claim 4 , wherein the p53 variant is characterized in that exon 7, exon 8 and/or exon 9 are partially or entirely are deleted. 
     
     
         6 . The isolated p53 variant according to  claim 4 , wherein the p53 variant comprises the amino acid sequence SEQ ID NO: 24 or an amino acid sequence having at least 90% homology to SEQ ID NO: 24 and is capable of transactivating the p21- and 14-3-3σ-promoter but not the mdm2-, bax- and PIG3-promoter. 
     
     
         7 . An antisense RNA sequence characterized in that it is complementary to an mRNA transcribed from a nucleic acid molecule of  claim 3  and can selectively bind to said mRNA or part thereof, said sequence being capable of inhibiting the synthesis of the protein encoded by said nucleic acid molecule. 
     
     
         8 . A ribozyme characterized in that it is complementary to an mRNA transcribed from a nucleic acid molecule of  claim 3  and can selectively bind to and cleave said mRNA or part thereof, thus inhibiting the synthesis of the protein encoded by said nucleic acid molecule. 
     
     
         9 . A recombinant vector or plasmid comprising the nucleic acid molecule of  claim 3 . 
     
     
         10 . The recombinant vector or plasmid according to  claim 9 , wherein the plasmid is DSM 15482 and deposited on Mar. 3, 2003. 
     
     
         11 . The recombinant host cell comprising the vector or plasmid according to  claim 9  which is a mammalian cell, a bacterial cell, an insect cell or a yeast cell. 
     
     
         12 . A method of making a p53 variant comprising: (a) culturing the recombinant host cell of  claim 10  under conditions such that said p53 variant is expressed; and (b) recovering said p53 variant. 
     
     
         13 . A pharmaceutical composition containing a molecule that inhibits the action of the p53 variant of  claim 4 , wherein the molecule is an antisense RNA, a ribozyme organ antibody. 
     
     
         14 . A diagnostic composition containing an oligonucleotide probe which is capable of specifically hybridizing to a nucleic acid molecule of  claim 1 , wherein the oligonucleotide probe comprises the nucleic acid sequence ATC ACA CTG GAT GGA (SEQ ID NO: 1) or the complementary sequence thereof. 
     
     
         15 . A method of increasing apoptosis in human cells comprising: administering an antisera specific for p53 variant of SEQ ID NO: 24 in a sufficient amount to effect protein-protein interaction of p53 variant with p21. 
     
     
         16 . A method of arresting the S cell cycle phase in a cell comprising contacting the cell with the p53 variant according to  claim 4  in an amount to increase DNA repair. 
     
     
         17 . A method for screening a potential cellular apoptosis inducing test compound for determining it utility as a therapeutic agent for increasing cell death, the method comprising: (a) contacting a cell which expresses a protein having an amino acid sequence SEQ ID NO: 24 or 95% homology having a function of transactivating the endogenous p21- and 14-3-3σ- but not the mdm2-, bax- and PIG3-promoter with the test compound; and; (b) determining the level of apoptosis activity of the cell, wherein an increase in apoptosis activity identifies a test compound that induces apoptotic activity. 
     
     
         18 . A method of for determining a tumor in a subject, the method comprising testing a biological sample of the subject for the presence of the p53 variant of  claim 4 . 
     
     
         19 . An isolated nucleotide sequence encoding a p53 variant, wherein the nucleotide sequence comprises a nucleic acid sequence selected from the group consisting of: (a) SEQ ID NO: 26; (b) a nucleic acid sequence that has more than 95% identity to a nucleic acid sequence of SEQ ID NO 26; (c) a nucleic acid sequence fully complementary to a nucleic acid of (a); and wherein the isolated p53 variant transactivates the endogenous p21- and 14-3-3σ- but not the mdm2-, bax- and PIG3-promoter.