Core modified 8-17 DNAzymes with 2'-deoxy-2'-C-methylpyrimidine nucleosides.

Area of Science:

• Biochemistry
• Molecular Biology
• Medicinal Chemistry

Background:

• DNAzymes are catalytic DNA molecules with therapeutic potential.
• STAT 3 is a key protein in various cancers, making it a target for drug development.
• Chemical modifications can enhance DNAzyme stability and efficacy.

Purpose of the Study:

• To investigate the impact of chemical modifications on the catalytic activity and stability of an 8-17 DNAzyme targeting STAT 3.
• To evaluate the role of 2'-deoxy-2'-C-methyl modifications at specific positions within the DNAzyme core.
• To assess the combined effects of core and binding arm modifications on DNAzyme performance.

Main Methods:

• Synthesis of DNAzymes with various modifications, including 2'-deoxy-2'-C-methyluridine, 2'-deoxy-2'-C-methylcytidine, 2'-O-methyl, and phosphorothioate nucleotides.
• Assay of catalytic activity (kact and kcat) of modified DNAzymes.
• Evaluation of DNAzyme stability against cell lysate.
• Structure-activity relationship analysis of chemical modifications.

Main Results:

• 2'-deoxy-2'-C-methyluridine modifications significantly reduced catalytic activity.
• 2'-deoxy-2'-C-methylcytidine modifications at positions 8 and 11 resulted in catalytic activity comparable to non-modified DNAzymes.
• Modifications in the binding arms affected catalytic efficiency unpredictably when combined with core modifications.
• Double 2'-C-methyl modification in the catalytic core enhanced DNAzyme stability by 70% against cell lysate.

Conclusions:

• Specific 2'-deoxy-2'-C-methylcytidine modifications can maintain or improve DNAzyme catalytic activity.
• The catalytic core's 2'-C-methyl modification significantly enhances DNAzyme stability.
• These findings provide a basis for developing more stable and effective DNAzyme-based therapeutics targeting STAT 3.