Published online Dec 15, 1999. doi: 10.3748/wjg.v5.i6.465
Revised: September 16, 1999
Accepted: October 10, 1999
Published online: December 15, 1999
AIM: To determine whether incorporation of the pH-dependent ba cterial toxin listeriolysin O (LLO) into the DNA carrier system could increase the endosomal escape of internalized DNA and result gene expression.
METHODS: A multi-component delivery system was prepared consist ing of asialoglycoprotein (ASG), poly L-lysine (PL), and LLO. Two marker genes, luciferase and β-galactosidase in plasmids were complexed and administered in vitro to Huh7[ASG receptor (+)] and SK Hep1 [ASG rece ptor(-)] cells. Purity, hemolytic activity, gene expression, specificity, and toxicity were evaluated.
RESULTS: An LLO-containing conjugate retained cell-targeting specificity and membranolytic activity. In ASG receptor (+) cells, luciferas e gene expression was enhanced by more than 7-fold over that of conjugates with out the incorporation of listeriolysin O. No significant expression occurred in ASG receptor (-) cells. Enhancement of β-galactosidase gene expression was less, but still significantly increased over controls. There was no detectable toxicity at concentrations shown to be effective in transfection studies.
CONCLUSIONS: ASOR-PL can be coupled to LLO using disulfide bonds, and successfully target and increase the gene expression of foreign DNA.