Cationic Transfectors Increase Accumulation in Cultured Tumor Cells of Radiolabeled Antisense DNAs Without Entrapment

While cellular accumulations in the culture of oligomers, such as interfering RNA and antisense DNA, are reported to benefit from the addition of transmembrane transfectors (TFs), the extent to which individual TFs improve cellular delivery is usually inferred and rarely measured. The goal of this investigation was to use radioactivity to measure in cells in culture the degree to which accumulations of DNA increased when complexed with TFs and without DNA entrapment in vesicles. The antisense (AS) DNA targeting mdr1 mRNA coding for P-glycoprotein (Pgp) and its sense (S) complement DNA were radiolabeled with ^99mTc and mixed with jetPEI^™ (Qbiogene Inc., Irvine, CA), Chariot^™, or Neophectin^™ (NeoPharm, Inc., Waukegan, IL) over a range of TF/DNA ratios. Thereafter, the radiolabeled DNAs with and without TFs were incubated with KB-G2 (and KB-31 (mdr1^+/− ) cells at 37°C in serum or serum-free media for 20–24 hours at a fixed DNA concentration of 13 nM. Cellular accumulations were increased under most incubation conditions and by as much as threefold with jetPEI and eightfold with Neophectin. As evidence against entrapment, the accumulations of AS DNAs were higher than S DNAs in virtually all measurements and higher in virtually all accumulations in the mdr1⁺⁺ cells, compared to the mdr1^+/− cells. In conclusion, in using radiolabeled DNAs, definitive evidence was obtained showing that the addition of Neophectin and jetPEI increased cellular accumulations of both AS and S DNA without evidence of vesicle entrapment.