Abstract
Gold nanobeacons can be used as a powerful tool for cancer theranostics. Here, we proposed a nanomaterial platform based on gold nanobeacons to detect, target and inhibit the expression of a mutant Kras gene in an in vivo murine gastric cancer model. The conjugation of fluorescently-labeled antisense DNA hairpin oligonucleotides to the surface of gold nanoparticles enables using their localized surface plasmon resonance properties to directly track the delivery to the primary gastric tumor and to lung metastatic sites. The fluorescently labeled nanobeacons reports on the interaction with the target as the fluorescent Cy3 signal is quenched by the gold nanoparticle and only emit light following conjugation to the Kras target owing to reorganization and opening of the nanobeacons, thus increasing the distance between the dye and the quencher. The systemic administration of the anti-Kras nanobeacons resulted in approximately 60% tumor size reduction and a 90% reduction in tumor vascularization. More important, the inhibition of the Kras gene expression in gastric tumors prevents the occurrence of metastasis to lung (80% reduction), increasing mice survival in more than 85%. Our developed platform can be easily adjusted to hybridize with any specific target and provide facile diagnosis and treatment for neoplastic diseases.
Highlights
Amolecular beacon is a hairpin DNA single-stranded oligonucleotide, which transports a dye and a quencher at both ends
Due to their optical properties, nanomaterials and nanoparticles in particular have been used for nucleic acid screening methodologies, through thiolated DNA oligonucleotides capable of recognizing specific nucleotide sequences[10,11,12,13]
Antisense DNA21,22 pathways have emerged as powerful and useful tools to block gene function and for sequence-specific posttranscriptional gene silencing. The discovery of their prominent role in regulation of specific gene expression in numerous disease states, such as cancer resulted into an enormous effort towards the development of new efficient delivery systems that control those pathways[23,24]
Summary
Characterization of the gold nanobeacons was performed by Dynamic Light Scattering – DLS (Wyatt Dyna Pro Plate Reader), UV/Vis Spectroscopy and TEM (see Supplementary Table S2). All measurements were performed in a microplate reader (Varioskan Flash Multimode Reader, Thermo Scientific) programmed to incubate the reactions for 120 min at 37 °C while recording the fluorescence intensity every 2 minutes at an excitation wavelength of 550 nm for Cy3-labeled gold nanobeacon. Biodistribution of the functionalized gold nanobeacons in tissues associated with clearance (liver, spleen and kidney) as well as the gastric tumor, lung and heart was measured by inductively coupled plasma mass spectrometry (ICP-MS). 5 days after gold nanobeacons administration, the mice were sacrificed to harvest the major organs, which were rinsed with ethanol three times and air-dried into clean vials for acid digestion (aqua-regia 3HCl:1HNO3). All in vivo experiments used 5 mice per treatment group unless noted otherwise
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