Compared to non specific LEPI siRNA NEG groups, treatment with a single dose of LPEI complexed siRNA EGFR resulted Vandetanib hypothyroidism in target gene expression down regulation under each N P ratio, with all differences being Inhibitors,Modulators,Libraries significant. Under an N P ratio of 5, 76. 42% of down regulation in EGFR mRNA was obtained at 24h after LPEI siRNA EGFR transfection. An EGFR protein reduction of 63. 53% was also confirmed by flow cytometry assays at 48h following treatment. These results were similar to those of the Lipofectamine siRNA EGFR transfected group. The lower efficiency at N P ratio of 3 may have been due to an insuf ficient complexation of siRNA by LPEI. Additionally, because the dose increase of LPEI under N P ratio of 10 did not lead to a higher silencing efficacy, the optimal N P ratio was considered as 5 for LPEI vectored siRNA EGFR delivery during the in vitro and further in vivo studies.

To explain the optimal silencing efficiency produced by LPEI complexed siRNA, the mean particle size and zeta potential distribution were determined. Further more, considering that jetPEI was introduced previously as a DNA plasmid transfection Inhibitors,Modulators,Libraries reagent, these parameters were compared with LPEI plasmid DNA complexes using the Inhibitors,Modulators,Libraries same N P ratio. As displayed in Table 1, the electrostatic interactions between LPEI and siRNA resulted in formation of complexes with average particle size distribution of 100 nm, while LPEI DNA com plexes showed 2 fold increase in size, revealing that LPEI siRNA complexes were more compact as com pared with LPEI DNA complexes. Similar lower positive surface potential were detected in both complexes.

LPEI siRNA EGFR complexes downregulate EGFR expression in SPC A1 xenografted tumor upon single i. p. injection The ultimate goal of our study was to explore the thera peutic use of EGFR specific siRNA through systemic Inhibitors,Modulators,Libraries application. Indeed, it has been known Inhibitors,Modulators,Libraries that many vectors have failed with in vivo gene delivery in spite of good transfection abilities in vitro. Therefore, we examined whether LPEI complexed siRNA EGFR under N P ratio of 5 could also induce efficient target gene silencing upon a single i. p. injection in vivo. SPC A1 xenografted mice were randomly divided into three groups. As tumors reached 6 mm��6 mm, each mouse was intraperitoneally injected with 0. 6 nmol of siRNA EGFR complexed with LPEI. Corresponding doses of LPEI siRNA NEG or 5% GS were administrated as towards control groups. Twenty four hours later, the mice were killed and their tumors pro cessed for RNA extraction. Quantitative real time PCR analysis revealed a 49% reduction of EGFR mRNA content of tumors treated with LPEI siRNA EGFR complexes in comparison with the non specific LPEI siRNA NEG control, the results showing no significant difference with GS control group.