Targeting Regulatory Effects Of Nucleic Acid Aptamer Modified Iron Nanoparticles On Tumor Hyperthermia And Immunotherapy

Objective To develop aptamer-modified nanoparticles (AptNPs) for targeted enhancement of thermal damage to HER2-positive breast cancer cells.Methods HER2aptamer was connected to NPs via biotin-streptavidin reaction. AptNPs were characterized by Dynamic Light Scattering (DLS). The binding feature of the aptamer was evaluated by flow cytometry, and the affinity of AptNPs to target cells by phase-contrast microscopy. Thermal damage under alternative magnetic field was measured by MTS assay.Results The average size of AptNPs was333.7nm. AptNPs exhibited strong binding to the HER2-positive but not the HER2-negative cells. Importantly, AptNPs enhanced the thermal damage to the HER2-positive tumor cells, but not that to the HER2-negative cells.Conclusions Aptamer-guided iron particles may have potential utility in development of novel HER2-targeted thermal therapies. Objective Breast cancer is the most common malignancy among women worldwide. HER2is overexpressed in20-30%of breast cancers. HER2-positive breast cancer is associated with high metastatic potential and poor prognosis. At present, HER2-targeted therapy was mainly achieved by the monoclonal antibody Trastuzumab (Herceptin). However, most Trastuzumab-treated patients will develop resistance to the antibody and become refractory to further treatment. Therefore, it is still necessary to explore new HER2-targeted therapeutic strategies. In this study, we explored the feasibility of applying nanotechnology to develop a new form of HER2-targeted therapy. Prior research on using nanotechnology for cancer treatment has mainly focused on improving the drug delivery to tumor cells. To date, nanotechnology has not been applied to directly pull together lymphocytes and tumor cells for targeted promotion of anticancer immune reaction. Here we designed an aptamer-based bispecific nanoparticle (NP) for pulling together the CD16-expressing natural killer (NK) cells and the HER2-positive breast cancer cells, to enhance the NK-mediated anticancer cytotoxicity.Methods In this study, through biotin-streptavidin reaction, we constructed a bispecific nanoparticle (NP) by implanting CD16and HER2aptamers onto the surface of a nanobead at the ratio of5:1. The binding feature of the CD16and HER2aptamers and whether this aptamers were connected onto nanobeads were evaluated by flow cytometry. The dynamic light scattering (DLS) instrument and the confocal microscopy were used to characterize the bispecific nanoparticle. Besides, the phase-contrast microscopy was used to study whether the bispecific NP could bind with the HER2-positive SK-BR-3and CD16-expressing NK cells, And also the phase-contrast microscopy was used to evaluate whether SK-BR-3and NK could pulled together by the bispecific nanoparticles. The NK cytotoxicity to the HER2-positive SK-BR-3and HER2-negative MDA-MB-231breast cancer cells was meassured by MTS assay. Results In this work, we designed a bispecific NP that was functionalized with both the CD16and the HER2aptamers, to pull together the CD16-expressing immunocytes and the HER2-positive tumor cells. The binding properties of the aptamers were verified with flow cytometry. The HER2and CD16aptamers was found capable of recognizing the HER2-positive SK-BR-3cells and the CD16-positive immunocytes, respectively. These aptamers were planted onto the NP via biotin-streptavidin interaction, as confirmed by hybridizing DNA probes that could recognize the aptamers. The average diameter of the bispecific NPs was351.7nm, with a mono-peak size distribution. Compared with the blank NPs, the bispecific NPs had markedly increased affinity to both the NK and the HER2-positive cancer cells. The bespecific nanoparticles could pull together the CD16-expressing immunocytes and the HER2-positive tumor cells. Importantly, the bispecific NPs significantly enhanced the NK cytotoxicity to the HER2-positive SK-BR-3breast cancer cells, but not that to the HER2-negative MDA-MB-231cells, indicating that the enhanced anticancer immune reaction was HER2-targeted.Conclusion A novel bispecific nanostructure was constructed by implanting CD16and HER2aptamers onto the surface of a nanoparticle. The bispecific NP could bind with both the CD16-expressing NK cells and the HER2-expresssing SK-BR-3breast cancer cells. Moreover, the bispecific NP elicited a targeted enhancement of the NK-mediated cytotoxicity to HER2-expressing breast cancer cells in vitro. The results suggest that aptamer-based bispecific nanostructure may have application potential for induction of NK-mediated reaction against HER2-positive tumors.