Tumor-targeted Delivery of siRNA by Self-assembled Nanoparticles

Abstract

We have developed a self-assembled nanoparticle (NP) that efficiently delivers small interfering RNA (siRNA) to the tumor by intravenous (IV) administration. The NP was obtained by mixing carrier DNA, siRNA, protamine, and lipids, followed by post-modification with polyethylene glycol and a ligand, anisamide. Four hours after IV injection of the formulation into a xenograft model, 70-80% of injected siRNA/g accumulated in the tumor, approximately 10% was detected in the liver and approximately 20% recovered in the lung. Confocal microscopy showed that fluorescent-labeled siRNA was efficiently delivered into the cytoplasm of the sigma receptor expressing NCI-H460 xenograft tumor by the targeted NPs, whereas free siRNA and non-targeted NPs showed little uptake. Three daily injections (1.2 mg/kg) of siRNA formulated in the targeted NPs silenced the epidermal growth factor receptor (EGFR) in the tumor and induced approximately 15% tumor cell apoptosis. Forty percent tumor growth inhibition was achieved by treatment with targeted NPs, while complete inhibition lasted for 1 week when combined with cisplatin. The serum level of liver enzymes and body weight monitoring during the treatment indicated a low level of toxicity of the formulation. The carrier itself also showed little immunotoxicity (IMT).

Efficient gene silencing in metastatic tumor by siRNA formulated in surface-modified nanoparticles

“…Signal of cy3-siRNA that were compactly formulated in NP and accumulated extracellularly was quenched and therefore, could not be shown in figure 4A (panel b). Our previous results suggest that PEGylated NP (with or without ligand) delivered comparable amount of siRNA to the tumor tissue but only targeted NP showed significant intracellular delivery [10]. As shown in figure 4C, normal lung expressed a basal level of sigma receptor and therefore, the targeted NP showed enhanced uptake in the lung compared to the non-targeted NP ( figure 4A).…”

“…A targeting ligand (anisamide) was conjugated to the distal end of PEG for targeting sigma receptor expressing tumor cells. The targeted NP formulation was shown to selectively deliver siRNA to receptor positive tumor cells in vitro [8,9] and in vivo [10]. Here, we investigated the efficiency of our targeted NP for delivering siRNA into an experimental metastatic tumor model, B16F10 lung metastasis in C57BL/6 mice.…”

Therapeutic targeting in the silent era: advances in non-viral siRNA delivery

“…As these ABCD formulations are nearly neutral or even negative in charge, the remarkable gene silencing data when administered systemically must be a result of active cell-specific targeting. Li and colleagues developed a nanoparticle formulation for successfully systemic delivery of siRNA into xenograft [122,80] and metastatic tumours [78,79] which produced anti-cancer effects. In this system, the nucleic acids (siRNAs and carrier DNA), a polycationic peptide (protamine) and a cationic liposome, were initially prepared in a condensed core.…”

“…The resulting core was then modified by PEG-lipid containing the tumour targeting ligand, anisamide (see above) [78][79][80] . The resulting targeted nanoparticles silenced the epidermal growth factor receptor (EGFR) in the tumour and induced ~15% tumour cell apoptosis without any indication of immunotoxicity [122] . In a mouse model of metastasis, a mixture of siRNA against the cancer associated proteins MDM2, c-myc, and VEGF, co-formulated in the targeted formulation, administered intravenously caused simultaneous silencing of each of the genes.…”

Systemic delivery of E6/7 siRNA using novel lipidic particles and its application with cisplatin in cervical cancer mouse models

“…Of these, the polyethylene glycol (PEG)ylated lipidic systems show promise, with early reports demonstrating their effectiveness in various cancer models. [4][5][6] The formulation procedures used in those studies, however, are labour intensive and require specialized equipments and skills. The resulting end products, being in aqueous states, are also not suitable for longterm storage.…”