DOUBLE-STRANDED RNA (dsRNA) AND METHOD OF USE FOR INHIBITING EXPRESSION OF A FUSION GENE

Abstract

Specific inhibition of expression of a fusion gene in mammals occurs using a short, double-stranded ribonucleic acid molecule (dsRNA). The dsRNA comprises two separate non-linked RNA strands, an 51 strand and a complementary strand. The strands are 20 to 23 nucleotides in length, and the 51 strand is complementary to the fusion junction of the AML-1/MTG-8 fusion gene. The dsRNA also comprises at least 3 nucleotides on each side of the fusion junction. The dsRNA can be introduced into and maintained in a mammalian cell under conditions and for a time sufficient to obtain degradation of mRNA of the fusion gene to inhibit expression of the fusion gene. The dsRNAs and methods described are useful for treating diseases caused by chromosomal aberrations, particularly malignant diseases such as lymphoma and leukemia.

1 . An isolated double-stranded ribonucleic acid molecule (dsRNA) comprising two separate non-linked RNA strands, an S1 strand and a complementary strand, wherein each of the S1 strand and the complementary strand is 20 to 23 nucleotides in length, and wherein the S1 strand is complementary to a fusion junction of an AML-1/MTG-8 fusion gene and comprises at least 3 nucleotides on each side of the fusion junction. 
     
     
         2 . The dsRNA of  claim 1 , wherein at least one end of the dsRNA is modified, in order to counteract degradation in the cell or dissociation of the dsRNA into individual RNA strands. 
     
     
         3 . The dsRNA of  claim 1 , wherein at least one of the S1 strand and the complementary strand is 21 nucleotides in length. 
     
     
         4 . The dsRNA of  claim 1 , wherein both of the S1 strand and the complementary strand are 21 nucleotides in length. 
     
     
         5 . The dsRNA of  claim 1 , wherein the dsRNA comprises at least 7 nucleotides on each side of the fusion junction that are complementary to the 7 nucleotides on each side of the fusion junction of the fusion gene. 
     
     
         6 . The dsRNA of  claim 1 , wherein at least one of the S1 strand and the complementary strand has a nucleotide overhang on the 3′-terminus. 
     
     
         7 . The dsRNA of  claim 1 , wherein at least one of the S1 strand and the complementary strand has a nucleotide overhang that is two nucleotides in length. 
     
     
         8 . The dsRNA of  claim 1 , wherein the cell is a leukocyte. 
     
     
         9 . The dsRNA of  claim 1 , wherein the cell is a myelogenic cell. 
     
     
         10 . The dsRNA of  claim 1 , wherein both of the S1 strand and the complementary strand are 21 nucleotides in length, and one of the S1 strand and the complementary strand has a 2-nucleotide overhang on the 3′-terminus. 
     
     
         11 . A method for inhibiting the expression of an AML-1/MTG-8 fusion gene in a mammalian cell, comprising the steps of:
 (a) introducing into a mammalian cell a dsRNA, said dsRNA comprising two separate non-linked RNA strands, an S1 strand and a complementary strand, wherein each of the S1 strand and the complementary strand is 20 to 23 nucleotides in length, and wherein the S1 strand is complementary to a fusion junction of an AML-1/MTG-8 fusion gene and comprises at least 3 nucleotides on each side of the fusion junction, and   (b) maintaining the cell produced in step (a) under conditions and for a time sufficient to obtain degradation of mRNA of the fusion gene to inhibit expression of the fusion gene in the cell.   
     
     
         12 . The method of  claim 11 , wherein at least one end of the dsRNA is modified, in order to counteract degradation in the cell or dissociation of the dsRNA into individual RNA strands. 
     
     
         13 . The method of  claim 11 , wherein at least one of the S1 strand and the complementary strand is 21 nucleotides in length. 
     
     
         14 . The method of  claim 11 , wherein both of the S1 strand and the complementary strand are 21 nucleotides in length. 
     
     
         15 . The method of  claim 11 , wherein the dsRNA comprises at least 7 nucleotides on each side of the fusion junction that are complementary to the 7 nucleotides on each side of the fusion junction of the fusion gene. 
     
     
         16 . The method of  claim 11 , wherein at least one of the S1 strand and the complementary strand has a nucleotide overhang on the 3′-terminus. 
     
     
         17 . The method of  claim 11 , wherein at least one of the S1 strand and the complementary strand has a nucleotide overhang that two nucleotides in length. 
     
     
         18 . The method of  claim 11 , wherein the cell is a myelogenic cell. 
     
     
         19 . The method of  claim 11 , wherein the cell is a leukocyte. 
     
     
         20 . The method of  claim 11 , wherein both of the S1 strand and the complementary strand are 21 nucleotides in length, and one of the S1 strand and the complementary strand has a 2-nucleotide overhang on the 3′-terminus.