ANTISENSE C-MYC OLIGONUCLEOTIDE CELLULAR UPTAKE AND ACTIVITY

Previously described cell membrane transport mechanisms are unable to account completely for oligodeoxynucleotide cellular uptake. These cha rged macromolecules enter cells by an incompletely defined mechanism a nd downregulate gene expression in either the cytoplasm or nucleus. Th us, the goal bf this research was to study the mechanism of phosphodie ster oligonucleotide cellular uptake in Rauscher Red 5-1.5 erythroleuk emia cells. An antisense c-myc oligodeoxynucleotide (21 bases) demonst rated biological activity in these cells using two types of proliferat ion assays and Northern blot analysis, and was internalized as visuali zed by confocal laser microscopy. Oligonucleotide uptake appeared to b e a complex process consisting of surface binding and internalization. Cellular internalization accounted for up to 40% of total uptake and was partially dependent on both a trypsin-sensitive component and cell ular energy. Uptake in these cells was nonspecific and did not appear to be due to receptor-mediated endocytosis. Therefore, because oligonu cleotide cellular uptake in other cell types apparently involves an en docytic mechanism, the primary mechanism of oligonucleotide internaliz ation may be cell line dependent.