Enhanced Human Epidermal Growth Factor Receptor 2 Degradation in Breast Cancer Cells by Lysosome-Targeting Gold Nanoconstructs

Abstract

This paper describes how gold nanoparticle nanoconstructs can enhance anti-cancer effects of lysosomal targeting aptamers in breast cancer cells. Nanoconstructs consisting of anti-HER2 aptamer (human epidermal growth factor receptor 2, HApt) densely grafted on gold nanostars (AuNS) first targeted HER2 and then were internalized via HER2-mediated endocytosis. As incubation time increased, the nanoconstruct complexes were found in vesicular structures, starting from early endosomes to lysosomes as visualized by confocal fluorescence and differential interference contrast microscopy. Within the target organelle, lysosomes, HER2 was degraded by enzymes at low pH, which resulted in apoptosis. At specific time points related to the doubling time of the cancer cells, we found that accumulation of HER2-HApt-AuNS complexes in lysosomes, lysosomal activity, and lysosomal degradation of HER2 were positively correlated. Increased HER2 degradation by HApt-AuNS triggered cell death and cell cycle arrest in the G0/G1 phase inhibition of cell proliferation. This work shows how a perceived disadvantage of nanoparticle-based therapeutics—the inability of nanoconstructs to escape from vesicles and thus induce a biological response—can be overcome by both targeting lysosomes and exploiting lysosomal degradation of the biomarkers.

Molecular Elucidation of Disease Biomarkers at the Interface of Chemistry and Biology

“…These results have inspired further research recently leading to combination with a nanocarrier to realize theranostic application. 57 These works showed the potential of aptamers as alternative therapeutics by their interactions with target biomarkers.…”

Copolymer micelles function as pH-responsive nanocarriers to enhance the cytotoxicity of a HER2 aptamer in HER2-positive breast cancer cells

“…52 The trimeric version of the HApt used in this study was initially developed by Mahlknecht et al, 41 who demonstrated that HApt promoted translocation of HER2 from the cell surface to the cytoplasm in HER2-overexpressing N87 gastric cancer cells, which was associated with lysosomedependent clearance of HER2 protein. Lee et al 40 reported that HApt exerted a cytotoxic effect in HER2-overexpressing SKBR3 breast cancer cells. HApt has been shown to induce cross-linking of HER2 on the cell surface, resulting in the translocation of HER2 to cytoplasmic vesicles for lysosomal degradation.…”

“…HER2-negative control aptamer (NCApt) is a trimeric concatenation of a negative control oligonucleotide (5′-AGATTGCACTTACTATCT-3′). 40,41 high performance liquid chromatography-purified HApt, NCApt, and other oligonucleotides (between 20 and 100 nt) (Table 1) were commercially synthesized (Sangon Biotech Co., Ltd., Shanghai, People's Republic of China). The dye Texas red was conjugated to the 5′-end of each oligonucleotide to enable fluorescent detection.…”

“…39,42,43 Recently, a 42 nucleotide (nt) trimeric anti-HER2 aptamer (HApt) derived from degradation of HER2 in lysosomes was reported to kill HER2-overexpressing N87 gastric cancer cells and SKBR3 breast cancer cells. 40,41 The anti-HApt exerts a cytotoxic effect by inducing crosslinking of HER2 on the cell surface, which results in the translocation of HER2 from the plasma membrane to cytoplasmic vesicles (mainly in lysosomes), where HER2 is thought to be degraded by proteases. 41 In this study, we extended the application of our PEG 8 -PDPA 100 -PEG 8 MNPs to the delivery of oligonucleotides.…”

Frizzled7 Antibody‐Functionalized Nanoshells Enable Multivalent Binding for Wnt Signaling Inhibition in Triple Negative Breast Cancer Cells

“…The ability to enhance tumor cell-specific binding or internalization of NPs with targeting agents like antibodies has been thoroughly investigated, [24,25] but only recently have researchers begun to examine the impact of these targeted NPs on downstream signaling events. [26,27] These studies are important because cell signaling manipulation by targeted nanoparticles is recognized as a promising therapeutic technique. [28] The rationale for using antibody-nanoparticle conjugates rather than freely delivered antibodies is supported by the fact that improvements in therapeutic efficacy have been observed for other molecules conjugated to or encapsulated within NPs, including peptides, [29] siRNAs or miRNAs, [30,31] chemotherapeutics, [32–34] or a combination of these.…”