Pharmaceutical Research on Antisense Origonucleotide

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Cationic liposomes were explored as non-viral vectors for which six cholesterol derivatives with various tertiary amines were newly synthesized as a lipid component. Cationic liposomes consisting of dioleoylphosphatidylethanolamine (DOPE) and the cholesterol derivatives were tested in terms of the frequency of transfection of plasmid pSV2 cat and the suppressing effect of the corresponding antisense (5'-GATCCCCCCCTCCAT-3') against the plasmid DNA.The following were clarified : (1) Fluorescence studies showed that the plasmid DNA forms a relatively large complex with the liposomes at an appropriate ratio (0.15 DNA/lipid, w/w) on these components and excess plasmid DNA lowered the transfection efficiency. (2) Antisense oligonucleotide also formed a large complex with the liposomes, which suppressed the gene expression of the plasmid DNA.(3) The structure of ths complexes formed between plasmid DNA and the liposomes may be different from that formed between the antisense and the liposomes. (4) A confocal microscope study showed that the whole complexes were taken into cells. To establish a new assay system for gene delivery, a human melanoma cell line (A-375-6) to which IL1 is known to stimulate the release of IL6 was selected and the effect of antisense (5'-TGTGGAGAAGGAGTT3') against IL6 was investigated. (1) Cationic liposome enhanced the release of IL6. (2) Antisense suppressed the enhancement by liposome, however, could not depress net release of IL6 stimulated with IL1 from A-375-6.