DNA cleavage by 111In-labeled oligodeoxyribonucleotides.

Area of Science:

• Radiochemistry
• Molecular Biology
• Biophysics

Background:

• The development of targeted DNA-damaging agents is crucial for cancer therapy.
• Radionuclides like Iodine-125 (125I) have been explored for sequence-specific DNA cleavage.
• Evaluating alternative radionuclides is essential for improving therapeutic efficacy and reducing side effects.

Purpose of the Study:

• To investigate the DNA damage fine structure induced by Indium-111 (111In) decay.
• To assess the potential of 111In incorporated into DNA for sequence-specific DNA cleavage.
• To compare the efficiency of 111In-induced DNA breaks with that of 125I.

Main Methods:

• Synthesis of oligodeoxyribonucleotides (ODNs) labeled with 111In using diethylenetriaminepentaacetic acid (DTPA) at various positions.
• Formation and confirmation of DNA duplexes and triplexes using gel electrophoresis.
• Assay of 111In-induced DNA breaks using denaturing polyacrylamide gel electrophoresis with single-nucleotide resolution.

Main Results:

• High specific activity 111In-labeled ODNs were synthesized without impeding DNA structure formation.
• Localized DNA breaks were observed in both duplex and triplex DNA structures.
• The yield of DNA breaks per 111In decay was comparable to 125I, with breaks primarily localized near the radionuclide attachment site.

Conclusions:

• 111In decay effectively produces highly localized DNA strand breaks.
• 111In-labeled ODNs demonstrate sequence-specific DNA cleavage capabilities.
• These findings support the application of 111In-ODNs in gene-specific radiotherapy.