Original Articles
Copyright ©The Author(s) 1999. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Dec 15, 1999; 5(6): 465-469
Published online Dec 15, 1999. doi: 10.3748/wjg.v5.i6.465
A DNA delivery system containing listeriolysin O results in enhanced hepatocyte-directed gene expression
Cherie M. Walton, Catherine H. Wu, George Y. Wu
Cherie M. Walton, Catherine H. Wu, George Y. Wu, Department of Medicine, Division of Gastroenterology-Hepatology, Univer sity of Connecticut Health Center, Farmington, CT
Author contributions: All authors contributed equally to the work.
Correspondence to: George Y. Wu, M.D., Ph.D., Department of Medi cine, Division of Gastroenterology-Hepatology, University of Connecticut Health Center, Farmington, CT 06030, USA. Wu@nso.uchc.edu
Telephone: (860)679-3878 Fax: (860)679-3159
Received: August 17, 1999
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.

Keywords: DNA, gene expression, listeriolysin O, hepatocytes