Cationic lipids employed for antisense oligodeoxynucleotide transport may inhibit vascular cell adhesion molecule-1 expression in human endothelial cells: A word of caution

Antisense oligodeoxynucleotides (ODN) have become a powerful tool to achiev e specific gene inhibition in various cell types, including endothelial cel ls. The low spontaneous cellular uptake of ODN, however, usually requires t he employment of transmembrane carriers, such as the positively charged lip osome formulation dioleyloxypropyltrimethyl ammonium chloride/dioleoylphosp hatidylethanolamine (DOTMA/DOPE). In the present study, we observed that DO TMA/DOPE per se interferes with the inducible expression of vascular cell a dhesion molecule-1 (VCAM-1) in human pulmonary artery endothelial cells (HP AEC), By RT-PCR analysis, a dose-dependent suppression of VCAM-1 but not in tracellular adhesion molecule-1 (ICAM-1) mRNA levels in tumor necrosis fact or-alpha (TNF-alpha)-challenged HPAEC pretreated with DOTMA/DOPE (5-20 mu g /ml) was demonstrated, Correspondingly, a strong reduction of TNF-alpha-ind uced VCAM-1 but not ICAM-1 cell surface expression on HPAEC was observed. T hese DOTMA/DOPE-induced changes were not due to alterations in VCAM-1 mRNA stability, nor did DOTMA/DOPE inhibit TNF-alpha-induced NF-kappa B-like bin ding activity in nuclear extracts of HPAEC, as analyzed by electrophoretic mobility shift assay. In contrast, DOTMA/DOPE effected a dose-dependent inc rease in AP-1-like binding activity in nuclear extracts of HPAEC, as analyz ed by Western blotting and EMSA. We conclude that positively charged liposo me preparations may per se inhibit TNF-alpha-induced endothelial VCAM-1 exp ression, and this may be related to changes in AP-1 but not NF-kappa Bdepen dent transcriptional control. Notably, when used at concentrations below 5 mu g/ml, DOTMA/DOPE may be employed for specific antisense-mediated downreg ulation of VCAM-1 in the absence of vehicle-related side effects on adhesio n molecule transcription.