Achieving Antisense Inhibition by Oligodeoxynucleotides Containing N7-Modified 2-Deoxyguanosine Using Tumor Necrosis Factor Receptor Type 1

Antisense oligodeoxynucleotides (ODNs) are being explored as therapeutic agents for the treatment of many disorders including viral infections, cancers, and inflammatory disorders. In addition, antisense technology can be of great benefit to those attempting to assign function to the multitude of new genes being uncovered in the genomics initiative. However, the demonstration that the gene-regulating effects produced by antisense-designed ODNs are attributable to an antisense mechanism of action requires carefully designed experimentation. Critical to the assignment of an antisense mechanism of action is the availability of nuclease-stable ODNs, inside cells, that have a high binding affinity with the target mRNA and modulate gene functions in a sequence-dependent manner. To help us achieve a goal of sequence-specific antisense activity we designed antisense ODNs containing C5-propyne-modified 2ʹ-deoxyuracil and N7-propyne-modified 7-deaza-2ʹ-deoxyguanosine bases and partially modified (phosphorothioate) internucleoside linkages. These modified ODNs were found to have enhanced binding affinity to their target mRNA sequences as well as reduced sequence-independent side effects. We used these ODNs to specifically inhibit p55 tumor necrosis factor receptor type 1 expression and tumor necrosis factor -mediated functions in culture assays.