Spacer-Arm Modulated Gene Delivery Efficacy of Novel Cationic Glycolipids:  Design, Synthesis, and in Vitro Transfection Biology

Design, syntheses and relative in vitro gene delivery efficacies of six novel cationic glycolipids 1−6 containing open-form galactosyl units in CHO, COS-1, MCF-7 and A549 cells are described. The results of the present structure−activity investigation convincingly demonstrate that the in vitro gene...

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Bibliographic Details
Published in:Journal of medicinal chemistry 2004-07, Vol.47 (16), p.3938-3948
Main Authors: Mahidhar, Yenugonda Venkata, Rajesh, Mukthavaram, Chaudhuri, Arabinda
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Biotechnology
Cell Line
Cercopithecus aethiops
Cricetinae
Deoxyribonuclease I - chemistry
DNA - administration & dosage
Fundamental and applied biological sciences. Psychology
Galactosidases - genetics
Gene therapy
Genes, Reporter
Glycolipids - chemical synthesis
Glycolipids - chemistry
Glycolipids - toxicity
Health. Pharmaceutical industry
Humans
Industrial applications and implications. Economical aspects
Liposomes - chemical synthesis
Liposomes - chemistry
Particle Size
Static Electricity
Structure-Activity Relationship
Transfection
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Summary:Design, syntheses and relative in vitro gene delivery efficacies of six novel cationic glycolipids 1−6 containing open-form galactosyl units in CHO, COS-1, MCF-7 and A549 cells are described. The results of the present structure−activity investigation convincingly demonstrate that the in vitro gene delivery efficacies of galactosylated cationic glycolipids are strikingly dependent on the absence of a spacer-arm between the open-form galactose and the positively charged nitrogen atom in their headgroup region. While the cationic glycolipids 1−3 with no headgroup spacer unit between the positively charged nitrogen and galactose showed high in vitro gene transfer efficacies in all four cells (lipids 1 and 2 with myristyl and palmityl tails, respectively, being the most efficacious), lipids 4−6 with five-carbon spacer units between the quaternized nitrogen and galactose heads were essentially transfection incompetent. The transfection inhibiting role of the five-carbon spacer unit in the headgroup region of the present novel class of cationic lipids was demonstrated by both β-galactosidase reporter gene expression and histochemical X-gal staining assays. Results of MTT assay-based cell viability measurements in representative MCF7 cells show that cell viabilities of lipoplexes (lipid:DNA complexes) prepared from all the lipids 1−6 are remarkably high. Thus, possibilities of differential cellular cytotoxicities playing any key role behind the strikingly contrasting transfection properties of lipids 1−3 with no spacer and lipids 4−6 with a spacer unit in the headgroup regions was ruled out. Electrophoresis gel patterns in DNase I sensitivity assays are consistent with more free DNA (accessible to DNase I) being present in lipoplexes of lipids 4−6 than in lipoplexes of lipids 1−3. Thus, the results of our DNase I protection experiments support the notion that enhanced degradation of DNA associated with lipoplexes of lipids 4−6 may play an important role in abolishing their in vitro gene transfer efficacies.
ISSN:0022-2623
1520-4804
DOI:10.1021/jm030464i