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Biomedical subjects

Jean-Paul Behr

Publications and source records attributed to Jean-Paul Behr.

22 records · Page 2Linked to original sources
PubMed2004

Sustained gene transfer and enhanced cell death following glucosylated-PEI-mediated p53 gene transfer with photochemical internalisation in p53-mutated head and neck carcinoma cells.

p53 is frequently mutated in head-and-neck squamous cell carcinoma. Wild-type p53 gene transfer induces apoptosis in vitro and tumor regression in vivo and clinical investigations of p53 gene therapy have been reported, mostly using viral vectors. Non-viral vectors are increasingly being used as an alternative to viral vectors and photochemical internalisation (PCI) of non-viral vectors has been reported to yield high gene transfer efficiency. The p53-mutated status of FaDu human pharynx carcinoma cell line was first assessed by DNA sequencing and the cells were transfected using tetraglucosylated polyethylenimine (PEI-Glu4) in conjunction with photochemical internalisation (PCI). The green fluorescent protein (GFP) was used as a reporter for determination of the transgene expression kinetics with or without PCI. p53 gene transfer was performed in these optimised conditions, and subsequent induction of apoptosis was investigated by flow cytometric determination of the phosphatidylserine externalization. Long-term cell death was assessed using colony forming assays. DNA sequencing in FaDu cells showed a G/T point mutation at codon 248 in exon 7 of p53 gene, resulting in an arginine-to-leucine substitution. As a consequence, P53 was shown to be expressed in >90% of untreated cells using immunocytochemistry. Using PEI-Glu4 as vector, PCI was found to significantly enhance GFP gene transfer whatever the formulation solution. Transfection efficiency was significantly increased with PCI. GFP expression kinetics (24-144 h) demonstrates that PCI induces sustained transgene expression with >10% of cells remaining transfected after 144 h. In such conditions, p53 gene transfer using PEI-Glu4 and PCI, resulted in spontaneous induction of apoptosis. As a consequence, long-term cell death was significantly enhanced after wt-p53 gene transfer when PCI was used, reaching up to 50% cell death. Wild-type p53 gene transfer using PEI-Glu4/DNA complexes and PCI, yields sustained transgene expression and induces cell death in p53-mutated FaDu cells.

Apoptosis↗
PubMed2002

In vivo growth inhibitory effect of iterative wild-type p53 gene transfer in human head and neck carcinoma xenografts using glucosylated polyethylenimine nonviral vector.

Polyethylenimine (PEI) derivatives are polycationic nonviral vectors for gene transfer. Previous results achieved in vitro in head and neck cancer cells demonstrated that glucosylated PEI yields higher gene transfer efficiency and longer transgene expression than unsubstituted PEI. Using glucosylated PEI, p53 gene transfer was successfully achieved with subsequent recovery of P53 protein expression and induction of spontaneous apoptosis. The present study reports in vivo data achieved in human head and neck squamous cell carcinoma xenografted mice. Using biotinylated PEI and histochemistry analysis, the vector was found to diffuse in the proliferating cells of the tumor tissue, sparing necrotic areas. No diffusion was observed inside keratinized area composed of nonproliferating, mature differentiated cells. Using green fluorescent protein (GFP) transfection and fluorescence microscopy, the transgene expression was mainly observed at the periphery of the tumor containing proliferating cells. GFP expression appeared lower inside the tumor depth. Quantitative transgene expression kinetics was then determined using luciferase as reporter gene. The maximal transgene expression was achieved 48 hours after intratumoral injection of glucosylated PEI/DNA complexes. The highest gene transfer efficacy was achieved 48 hours after two intratumoral injection. After transfection of wild-type p53, tumor growth inhibition was observed in tumor-bearing mice receiving intratumoral injection of glucosylated PEI/DNA complexes repeated twice weekly. Tumor growth inhibition was maintained under continuous treatment using the same schedule. In all experiments, no noticeable toxicity was observed. The present results demonstrate the feasibility and the tumor growth inhibition potency of nonviral gene transfer using glucosylated polyethylenimine.

Genes, p53↗
PubMedDate not supplied

Intracellular delivery of nanometric DNA particles via the folate receptor.

The size of condensed DNA particles is a key determinant for both diffusion to target cells in vivo and intracellular trafficking. The smallest complexes are obtained when each DNA molecule collapses individually. This was achieved using a designed cationic thiol-detergent, tetradecyl-cysteinyl-ornithine (C(14)COrn). The resulting particles were subsequently stabilized by air-induced dimerization of the detergent into a disulfide lipid on the DNA template. Particles are anionic (zeta potential = -45 mV), and their size (30 nm) corresponds to the volume of a single plasmid DNA molecule. The electrophoretic mobility of the condensed DNA, though quasi-neutralized, was found higher than that of the extended DNA. Moreover, the dimerized (C(14)COrn)(2) lipid was found to be an efficient transfection reagent for various cell lines. In an attempt to achieve extended circulation times and to target tumors by systemic delivery, we have coated the particles with PEG-folate residues. Plasmid DNA was condensed into monomolecular particles as described above and coated by simple mixing with DPPE-PEG-folate. Physicochemical measurements showed particles coated with 2% of DPPE-PEG(3400)-folate remain monomolecular and are stable in the cell-culture medium. Caveolae-mediated cell entry was demonstrated by ligand-dependence, by competition with excess folic acid as well as by confocal microscopy.

3T3 Cells↗