RESUMO
siRNA therapy research has primarily focused on the synthesis and development of effective siRNA delivery vectors with easy biodegradability and low toxicity. In the present study, we synthesized a ternary copolymer mPEG-b-PLL-g-(ss-lPEI), denoted as PLI, by introducing disulfide bond linkages to graft low molecular weight linear polyethylenimine (lPEI) to the block copolymer of poly(L-lysine) (PLL) and poly(ethylene glycol) (PEG) for siRNA delivery. The PLL block and disulfide linkage rendered the carrier biodegradability, while lPEI grafting brought about the proton buffering capacity for lysosomal siRNA release and low cationic toxicity. Conjugation of a single chain monoclonal antibody (Herceptin) to the carrier as a targeting ligand for the Her2/neu receptor significantly increased the transfection activity of the copolymer/siRNA nanocomplex (i.e. the polyplex) in Skov-3, a human ovarian cancer cell line. Determination of gene expression at both the mRNA and protein levels demonstrated that Her2-targeted delivery of siRNA (XIAP siRNA) effectively downregulated the targeted XIAP (X-linked inhibitor of apoptosis protein) gene, resulting in enhanced cancer cell apoptosis and improved therapeutic efficacy in vitro and in vivo. The distinct features of low cytotoxicity, easy degradability, and high siRNA transfection efficiency make the copolymer a promising candidate for siRNA therapy in tumors.
Assuntos
Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Polietilenoglicóis/química , Polietilenoimina/química , Polilisina/química , RNA Interferente Pequeno/química , Animais , Apoptose , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Dissulfetos , Feminino , Perfilação da Expressão Gênica , Inativação Gênica , Terapia Genética , Vetores Genéticos , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Transplante de Neoplasias , Neoplasias Ovarianas/terapia , Prótons , Proteínas Inibidoras de Apoptose Ligadas ao Cromossomo X/metabolismoRESUMO
Ultrasound (US)-sensitive nanobubble (NB) which may utilize the physical power of US exposure to improve delivery efficiency to target cells is emerging as one of the most promising nanocarriers for drug delivery. On the basis of successfully fabricating NBs with the ability of passively accumulating in tumor tissue, in this study we synthesized a US-sensitive NB bearing siRNA (siRNA-NB) for tumor therapy via a hetero-assembling strategy using the siRNA-complexed polymeric micelles and gas-cored liposomes. The US exposure-aided siRNA transfection effectively enhanced the gene silencing effect of siRNA-NBs both in vitro and in vivo, which resulted in much elevated level of cancer cell apoptosis. Consequently, significantly improved therapeutic effect was achieved in a nude mouse glioma model, using siRNA-NBs bearing siRNA to target the anti-apoptosis gene sirtuin 2 (SIRT2). These results show that, with the aid of US exposure, the US-sensitive siRNA-NB may be an ideal delivery vector to mediate highly effective RNA interference for tumor treatment.
