Tumor-targeted in vivo gene silencing via systemic delivery of cRGD-conjugated siRNA

Abstract

RNAi technology is taking strong position among the key therapeutic modalities, with dozens of siRNA-based programs entering and successfully progressing through clinical stages of drug development. To further explore potentials of RNAi technology as therapeutics, we engineered and tested VEGFR2 siRNA molecules specifically targeted to tumors through covalently conjugated cyclo(Arg-Gly-Asp-d-Phe-Lys[PEG-MAL]) (cRGD) peptide, known to bind αvβ3 integrin receptors. cRGD-siRNAs were demonstrated to specifically enter and silence targeted genes in cultured αvβ3 positive human cells (HUVEC). Microinjection of zebrafish blastocysts with VEGFR2 cRGD-siRNA resulted in specific inhibition of blood vessel growth. In tumor-bearing mice, intravenously injected cRGD-siRNA molecules generated no innate immune response and bio-distributed to tumor tissues. Continuous systemic delivery of two different VEGFR2 cRGD-siRNAs resulted in down-regulation of corresponding mRNA (55 and 45%) and protein (65 and 45%) in tumors, as well as in overall reduction of tumor volume (90 and 70%). These findings demonstrate strong potential of cRGD-siRNA molecules as anti-tumor therapy.

Cyclic hexapeptide-conjugated nanoparticles enhance curcumin delivery to glioma tumor cells and tissue

“…18 We cultured HUVECs in DMEM and C6 cells in MEM (both media were supplemented with 10% fetal bovine serum) at 37°C with 5% CO 2 . The medium was replaced every 1-2 d, and the growth state of the cells was observed daily through an inverted microscope.…”

Reductive nanocomplex encapsulation of cRGD-siRNA conjugates for enhanced targeting to cancer cells

“…Integrin α v β 3 -negative HeLa cells 9 were selected to investigate the effect of the interaction between pepetide and CLD to form nanocomplexes on cell uptake. HeLa cells were incubated with 100 nM CLD/FAM-siRNA for 6 h, and the corresponding results are shown in Figure 5C.…”

“…8 A common cell-targeting peptide is Arg-Gly-Asp peptide sequence (cRGD), which implement endocytosis by binding to overexpressed integrin αvβ3 receptors on tumor cell surface. 9 Many reports have demonstrated that the transport capacity of siRNAs was significantly improved when siRNAs were covalently conjugated with cRGD peptides. [9][10][11] For example, Alam et al conjugated the divalent, trivalent and tetravalent cRGD to the 3′-terminus of the sense strand of siRNA via thioether bonds.…”

“…9 Many reports have demonstrated that the transport capacity of siRNAs was significantly improved when siRNAs were covalently conjugated with cRGD peptides. [9][10][11] For example, Alam et al conjugated the divalent, trivalent and tetravalent cRGD to the 3′-terminus of the sense strand of siRNA via thioether bonds. 10 Although the intracellular uptake efficiency of cRGD-siRNA conjugates with different multivalent values was not significantly different, the trivalent/ tetravalent cRGD-siRNA conjugate showed enhanced luciferase silencing effect.…”

Complete destruction of deep-tissue buried tumors via combination of gene silencing and gold nanoechinus-mediated photodynamic therapy

“…Gene therapy involves knocking down or silencing of specific oncogenes, and plays a vital role in treating surface tumors [13,14]. Superoxide dismutase 1 (SOD1) is one of the very effective anti-apoptotic and self-defending genes, and can destroy the free radicals or reactive oxygen species in the human body.…”