OLIGONUCLEOTIDE BIOLOGICAL-ACTIVITY - RELATIONSHIP TO THE CELL-CYCLE AND NUCLEAR TRANSPORT

Previous studies suggest that oligodeoxynucleotide (ODN) cellular upta ke is cell cycle-dependent which may have important implications in ca ncer cell targeting. To further our understanding of ODN transport and activity, this study examines the relationships between the cell cycl e, ODN cellular uptake, intracellular transport, and activity. An anti sense c-myc ODN 21-mer was used to study ODN cellular uptake in Rausch er erythroleukemia cells synchronized by either chemical methods or fl ow cytometry. ODN uptake was examined using subcellular fractionation and confocal fluorescence microscopy. Western blot analysis was used t o measure ODN-mediated decreases in c-myc protein levels. Intracellula r ODN distribution and extent of uptake was influenced by the phase of the cell cycle, but the mechanism of uptake was not. The relative act ivity of the antisense ODN was positively correlated to ODN distributi on to the cytosol, but negatively correlated to total cellular uptake. Although ODN total cellular uptake is positively influenced by the ce ll cycle, retention of the ODN in the cytosol (presumably extra-vesicu larly) appeared to be relevant in determining the activity of an antis ense ODN. Novel methods to target cytosol-acting drugs to the cytoplas m may therefore be warrented.