Claude Malvy

Nanodiamond as a Vector for siRNA Delivery to Ewing Sarcoma Cells

The ability of diamond nanoparticles (nanodiamonds, NDs) to deliver small interfering RNA (siRNA) into Ewing sarcoma cells is investigated with a view to the possibility of in-vivo anticancer nucleic-acid drug delivery. siRNA is adsorbed onto NDs that are coated with cationic polymer. Cell uptake of NDs is demonstrated by taking advantage of the NDs intrinsic fluorescence from embedded color-center defects. Cell toxicity of these coated NDs is shown to be low. Consistent with the internalization efficacy, a specific inhibition of EWS/Fli-1 gene expression is shown at the mRNA and protein level by the ND-vectorized siRNA in a serum-containing medium.

Efficacy of dendrimer‐mediated angiostatin and TIMP‐2 gene delivery on inhibition of tumor growth and angiogenesis: In vitro and in vivo studies

Gene transfer is an attractive approach to fight cancer by targeting cancer cells or their vasculature. Our study reports the inhibition of tumor growth and angiogenesis by a nonviral method using dendrimers associated with 36‐mer anionic oligomers (ON36) for delivering angiostatin (Kringle 1–3) and tissue inhibitor of metalloproteinase (TIMP)‐2 genes. The optimal concentrations of dendrimers and ON36 for an efficient green fluorescent protein (GFP) plasmid delivery in endothelial cells (HMEC‐1) and cancer cells (MDA‐MB‐435) were first chosen. Then the efficacy of transfection was determined by testing angiostatin and TIMP‐2 secretion by Western blot and the biologic effects were evaluated. Angiostatin gene transfer markedly reduced in vitro (i) HMEC‐1 but not MDA‐MB‐435 proliferation; (ii) HMEC‐1 and MDA‐MB‐435 wound healing reparation; and (iii) capillary tube formation. TIMP‐2 gene transfer did not affect cell proliferation but strongly inhibited (i) wound healing of HMEC‐1 and MDA‐MB‐435 cells; and (ii) capillary tube formation. Supernatants of transfected‐MDA‐MB‐435 cells also inhibited the formation of angiogenic networks on Matrigel, indicating a paracrine effect. In vivo, intratumoral angiostatin or TIMP‐2 gene delivery using dendrimers associated with ON36 effectively inhibited tumor growth by 71% and 84%, respectively. Combined gene transfer resulted in 96% inhibition of tumor growth. Tumor‐associated vascularization was also greatly reduced. These findings provide a basis for the further development of nonviral delivery of genes to fight cancer.

Ellipticine and derivatives induce breakage of L1210 cells DNA in vitro

Abstract Part of the radioactive DNA extracted from prelabelled L1210 cells exposed in vitro to ellipticine, 9-hvdroxyellipticine, 2-methyl-9-hydroxyellipticinium and 9-aminoellipticine, migrate more slowly into an alkaline sucrose gradient. These effects occur in less than one hr of exposure, and can be detected at drug concentrations which lie respectively around 1000, 20, 100 and 500 ng per ml whereas the drug concentrations which inhibit by 50 per cent the rate of the in vitro cell growth are 242, 3.9, 13 and 53 ng per ml. The DNA breaks become rapidly undetectable when the cells exposure to the drugs is discontinued.