Targeted Delivery of PLK1-siRNA by ScFv Suppresses Her2 ⁺ Breast Cancer Growth and Metastasis

Abstract

A major obstacle to developing small interfering RNAs (siRNAs) as cancer drugs is their intracellular delivery to disseminated cancer cells. Fusion proteins of single-chain fragmented antibodies (ScFvs) and positively charged peptides deliver siRNAs into specific target cells. However, the therapeutic potential of ScFv-mediated siRNA delivery has not been evaluated in cancer. Here, we tested whether Polo-like kinase 1 (PLK1) siRNAs complexed with a Her2-ScFv-protamine peptide fusion protein (F5-P) could suppress Her2(+) breast cancer cell lines and primary human cancers in orthotopic breast cancer models. PLK1-siRNAs transferred by F5-P inhibited target gene expression, reduced proliferation, and induced apoptosis of Her2(+) breast cancer cell lines and primary human cancer cells in vitro without triggering an interferon response. Intravenously injected F5-P/PLK1-siRNA complexes concentrated in orthotopic Her2(+) breast cancer xenografts and persisted for at least 72 hours, leading to suppressed PLK1 gene expression and tumor cell apoptosis. The intravenously injected siRNA complexes retarded Her2(+) breast tumor growth, reduced metastasis, and prolonged survival without evident toxicity. F5-P-mediated delivery of a cocktail of PLK1, CCND1, and AKT siRNAs was more effective than an equivalent dose of PLK1-siRNAs alone. These data suggest that F5-P could be used to deliver siRNAs to treat Her2(+) breast cancer.

Low-weight polyethylenimine cross-linked 2-hydroxypopyl-ß-cyclodextrin and folic acid as an efficient and nontoxic siRNA carrier for gene silencing and tumor inhibition by VEGF siRNA

“…There are also other nonviral vector-mediated methods using polyethylene glycol-grafted polyethylenimine (PEI), peptides, low molecular weight chitosan, aptamer, serum albumin, and quantum dots. [6][7][8][9][10][11] The most widely used nonviral siRNA delivery systems are based on cationic lipids and cationic polymers. 12 Cationic lipids can bind nucleic acid to form liposomes and achieve highly efficient gene silencing, as reported in the literature.…”

Special delivery: targeted therapy with small RNAs

“…Intravenous injection of these fusion proteins complexed with siRNAs directed against oncogenes or PLK1, required for formation of the mitotic spindle, inhibits outgrowth of tumors bearing the antibody ligands. 50,51 Hematopoietic cells are a special challenge for nucleic acid delivery, as they are disseminated through the body and are resistant to all conventional in vitro transfection methods other than electroporation or infection with viral vectors. Having a way to induce gene silencing in leukocytes could be the basis for therapies for autoimmune and inflammatory diseases, transplant rejection, leukemia and lymphoma, and some viral infections.…”

Hypoxia-responsive ionizable liposome delivery siRNA for glioma therapy

“…PLK1 has been reported to play important roles in malignant glioma. 34,[42][43][44] RNAi-mediated PLK1 depletion or inhibition of PLK1 activity with siPLK1 induced G2/M arrest and apoptosis in glioma cells. Herein, the ability of downregulating therapeutic target mRNA level by siPLK1 delivered by MLP was assessed by RT-PCR.…”