Tracking the down-regulation of folate receptor-α in cancer cells through target specific delivery of quantum dots coupled with antisense oligonucleotide and targeted peptide.
Based on the multivalent binding capability of streptavidin (SA) to biotin, a multifunctional quantum dot probe (QD-(AS-ODN+p160)) coupled with antisense oligonucleotide (AS-ODN) and peptide p160 is designed for real-time tracking of targeted delivery of AS-ODN and regulation of folate receptor-α (hFR-α) in MCF-7 breast cancer cells. Fluorescence spectra, capillary electrophoresis (CE) and dynamic light scattering (DLS) are used to characterize the conjugation of AS-ODN and p160 with quantum dots (QDs), DLS results confirm the well stability of the probe in aqueous media. Confocal imaging and quantitative flow cytometry show that QD-(AS-ODN+p160) is able to specifically target human breast cancer MCF-7 cells. Low temperature and ATP depletion treatments reveal the cellular uptake of QD-(AS-ODN+p160) is energy-dependent, and the effects of inhibition agents and co-localization imaging further confirm the endocytic pathway is mainly receptor-mediated. Transmission electron microscopy (TEM) shows the intracellular delivery and endosomal escape of QD probe along with incubation time extended. Two transfection concentrations of QD probe (10 nM and 50 nM) below half inhibitory concentration (IC50 ) value are chosen according to MTT assay. Real-time PCR shows at these two concentration cases the relative mRNA expression levels of hFR-α reduce to 72.5 ± 3.9% and 17.6 ± 1.0%, respectively. However, western blot and quantitative ELISA analysis show the expression level of hFR-α protein has a significant decrease only at 50 nM, indicating that gene silence is concentration-dependent. These results demonstrate that the QD-(AS-ODN+p160) probe not only achieves gene silence in a cell-specific manner but also achieves real-time tracking during AS-ODN intracellular delivery.
['Zhang|Ming-Zhen|MZ|', 'Yu|Yong|Y|', 'Yu|Rong-Na|RN|', 'Wan|Min|M|', 'Zhang|Rong-Ying|RY|', 'Zhao|Yuan-Di|YD|']
D016503:Drug Delivery Systems D005434:Flow Cytometry D058975:Folate Receptor 1 D015972:Gene Expression Regulation, Neoplastic D006367:HeLa Cells D056945:Hep G2 Cells D006801:Humans D020128:Inhibitory Concentration 50 D061986:MCF-7 Cells D018613:Microscopy, Confocal D046529:Microscopy, Electron, Transmission D036103:Nanotechnology D009369:Neoplasms D016376:Oligonucleotides, Antisense D010455:Peptides D045663:Quantum Dots D034741:RNA, Small Interfering D019809:Streptavidin
quantum dots antisense oligonucleotide peptide transfection cell-type specific targeting