Delivery of chemo-sensitizing siRNAs to HER2+-breast cancer cells using RNA aptamers

Abstract

Human epidermal growth factor receptor 2 (HER2) expression in breast cancer is associated with an aggressive phenotype and poor prognosis, making it an appealing therapeutic target. Trastuzumab, an HER2 antibody-based inhibitor, is currently the leading targeted treatment for HER2+-breast cancers. Unfortunately, many patients inevitably develop resistance to the therapy, highlighting the need for alternative targeted therapeutic options. In this study, we used a novel, cell-based selection approach for isolating ‘cell-type specific’, ‘cell-internalizing RNA ligands (aptamers)’ capable of delivering therapeutic small interfering RNAs (siRNAs) to HER2-expressing breast cancer cells. RNA aptamers with the greatest specificity and internalization potential were covalently linked to siRNAs targeting the anti-apoptotic gene, Bcl-2. We demonstrate that, when applied to cells, the HER2 aptamer-Bcl-2 siRNA conjugates selectively internalize into HER2+-cells and silence Bcl-2 gene expression. Importantly, Bcl-2 silencing sensitizes these cells to chemotherapy (cisplatin) suggesting a potential new therapeutic approach for treating breast cancers with HER2+-status. In summary, we describe a novel cell-based selection methodology that enables the identification of cell-internalizing RNA aptamers for targeting therapeutic siRNAs to HER2-expressing breast cancer cells. The future refinement of this technology may promote the widespread use of RNA-based reagents for targeted therapeutic applications.

In vivo evaluation of cetuximab-conjugated poly(γ-glutamic acid)-docetaxel nanomedicines in EGFR-overexpressing gastric cancer xenografts

“…This is well correlated with previously reported studies. 58,59 In the HPLC quantification of DOCT from the MKN-28 cancer-bearing mice, a time-dependent reduction in plasma concentration of DOCT was observed, indicating eventual clearance of the Nps or the released DOCT from the circulation following the hepatic or renal route as indicated by liver and kidney accumulation, respectively. Studies have reported that even PEG modification could not enhance the circulation time, and that the Nps were cleared by the RES system following liver and spleen accumulation.…”

Gene Knockdown by EpCAM Aptamer–siRNA Chimeras Suppresses Epithelial Breast Cancers and Their Tumor-Initiating Cells

“…We deliver siRNAs into epithelial cancer cells by linking them to an RNA aptamer that binds to EpCAM, the first described tumor antigen, a cell surface receptor overexpressed on epithelial cancers, including basal-like TNBCs. Aptamer-linked siRNAs, known as aptamer-siRNA chimeras (AsiC), have been used in small animal models to treat prostate cancer and prevent HIV infection (10)(11)(12)(13)(14)(15)(16)(17)(18). We chose EpCAM for targeting basal-like TNBC because EpCAM is highly expressed on all epithelial cancers.…”

Use of Oligonucleotide Aptamer Ligands to Modulate the Function of Immune Receptors

“…1) is time consuming, costly, and often fails to identify high-affinity aptamer due to PCR bias (PCR is used after each round to amplify the target bound aptamers). In several recent studies, highthroughput sequencing enabled the identification of high-affinity aptamers after many fewer rounds of selection, reducing time, cost, and PCR bias (12)(13)(14)(15). In the standard protocol, aptamers are selected against recombinant protein products in solution.…”