Binding Features of BCL2‐Targeted Oligodeoxynucleotides with K562 Cells

Delivery of various oligodeoxynucleotides into cells is mediated by binding to certain surface proteins followed by receptor‐mediated endocytosis. Moreover, oligonucleotides are able to provoke perturbation of cell surface proteins and growth factor receptors among them. Here we described binding sense BCL2 oligodeoxynucleotide targeted to translation start of BCL2 mRNA (ODN) with K562 cells. At low concentration ODN bound efficiently with K562 and penetrated into the cells via binding cell surface with rather high affinity and priming new binding sites. The loose binding constant at 4°C was 1.8 × 109 M− 1 both for binding ODN in solution and ODN‐associated liposome. The number of loose binding sites under both treatments was rather high: 4.6 to 6.6 pmoles per 106 cells. The extent of ODN penetration into the cells showed higher potential site numbers than initially seen and reached 8.6 pmoles per 106 cells for four hours incubation at 37°C.