title: Co-liposomes having anisamide tagged lipid and cholesteryl tryptophan trigger enhanced gene transfection in sigma receptor positive cells.
abstract: Selective gene transfection could be strategy of interest for reducing off-target gene expression and toxicity. In this respect, sigma receptors are found to be over-expressed in many human tumors and liposomal formulations with ability to target these sigma receptors may improve the transfection efficiency to a significant level. To this direction, six novel lipids have been synthesized with different hydrophobic segments such as a long hydrophobic chain or a cholesteryl group and L-tryptophan as the head group. Three of them, Lipid 1, 3 and 5 possessed cationic Me3N(+) moiety at the distal end. In contrast each of the other three Lipid 2, 4 and 6 possessed sigma receptor targeting anisamide group with no cationic charge. Mixing of cationic and anisamide counterparts of the same lipid in a molar ratio of 1:1 produced co-liposomes L-M-1 (Lipid 1+2), L-M-2 (Lipid 3+4) and L-M-3 (Lipid 5+6). These co-liposomes, while keeping the sigma targeting anisamide tag intact, showed good DNA binding and release which were optimized from EB intercalation and gel electrophoresis assays. Inclusion of a zwitterionic, fusogenic natural lipid, DOPE, into the co-liposomes further improved the binding efficiencies of the lipid mixtures with DNA. These co-liposomes having cationic and anisamide lipids and DOPE were highly selective toward sigma positive HEK293 and HEK293T cells compared to the sigma negative HeLa cells. As evidenced from both FACS and luciferase assay, a lipid mixture comprising Lipid 3, 4 and DOPE in a molar ratio of 1:1:1 (L-M-2D1) was the best for transfection of reporter pEGFP-C3 and functional pCEP4-p53 gene plasmids. Anisamide mediated sigma receptor selectivity was further probed by pre-incubating the transfecting cells with lipids possessing anisamide and by quantification of the un-transfected plasmid DNA. Also each formulation was highly non-toxic in the cell lines examined.
authors.affiliation: Department of Organic Chemistry, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Santosh K
authors.initials: SK
authors.lastname: Misra
authors.affiliation: Department of Organic Chemistry, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Parikshit
authors.initials: P
authors.lastname: Moitra
authors.affiliation: Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Paturu
authors.initials: P
authors.lastname: Kondaiah
authors.affiliation: Department of Organic Chemistry, Indian Institute of Science, Bangalore 560 012, India; Chemical Biology Unit of Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India; Indian Association for the Cultivation of Science, Kolkata 700 032, India. Electronic address: sb@orgchem.iisc.ernet.in.
authors.forename: Santanu
authors.initials: S
authors.lastname: Bhattacharya
mesh_terms: D001549:Benzamides / Q000737:chemistry* / Q000378:metabolism; D002788:Cholesterol Esters / Q000737:chemistry* / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D015870:Gene Expression; D017930:Genes, Reporter; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008081:Liposomes / Q000737:chemistry* / Q000378:metabolism; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000737:chemistry / Q000378:metabolism; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017480:Receptors, sigma / Q000235:genetics / Q000378:metabolism*; D014162:Transfection / Q000379:methods*; D014364:Tryptophan / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001549:Benzamides; D002788:Cholesterol Esters; D008081:Liposomes; D010714:Phosphatidylethanolamines; D017480:Receptors, sigma; C094877:dioleoyl phosphatidylethanolamine; D014364:Tryptophan; D004247:DNA; D008156:Luciferases
keywords: Anisamide tagging; Cationic liposomes; Cytotoxicity; Reporter and functional gene expression; Sigma receptor targeting; Transfection