Dual receptor-specific peptides modified liposomes as VEGF siRNA vector for tumor-targeting therapy.

Tumor angiogenesis involves multiple signaling pathways that provide potential therapeutic targets to inhibit tumor growth and metastasis. Regarding the significant role of vascular endothelial growth factor (VEGF) in angiogenesis and tumor progression, VEGF sequence-specific small interfering RNA (siRNA) for anti-angiogenic tumor therapy are under development. In the present study, dual-modified liposomes (At-Lp) was designed by attaching two receptorspecific peptides, Angiopep and tLyP-1, which specifically targeting low-density lipoprotein receptor (LRP) for brain tumor targeting and neuropilin-1 receptor (NRP-1) for tumor penetration, respectively. Gene transfection and silencing, and antitumor effect of the At-Lp loaded with VEGF siRNA were evaluated in vitro and in orthotopic xenograft models of U87 MG tumor. The At-Lp significantly enhanced cellular uptake (2-fold) and down-regulated expression of VEGF in U87 MG glioblastoma cells compared with non-modified and single-modified liposomes. The internalization of the At-Lp into tumor cells was taken via the enhanced permeability and retention effect and receptor-mediated endocytosis, followed by an effective endosomal escape of loaded siRNA into the cytoplasm. The At-Lp showed great superiority in inhibition of tumor growth, anti-angiogenesis, expression of VEGF and apoptosis effect after in vivo application against nude mice bearing U87 MG glioblastoma without activation of system-associated toxicity and the innate immune response. These results demonstrated that the combination of two receptor-specific peptides-mediated liposomes presented a promising platform for effective targeting delivery of siRNA for cancer anti-angiogenic therapy.