Dataset Information

Visualization of microRNA-21 Dynamics in Neuroblastoma Using Magnetic Resonance Imaging Based on a microRNA-21-Responsive Reporter Gene.

ABSTRACT:

Background

MicroRNAs (miRs) have been shown to be closely associated with the occurrence and development of tumors and to have potential as diagnostic and therapeutic targets. The detection of miRs by noninvasive imaging technology is crucial for deeply understanding their biological functions. Our aim was to develop a novel miR-21-responsive gene reporter system for magnetic resonance imaging (MRI) visualization of the miR-21 dynamics in neuroblastoma.

Methods

The reporter gene ferritin heavy chain (FTH1) was modified by the addition of 3 copies of the sequence completely complementary to miR-21 (3xC_miR-21) to its 3'-untranslated region (3' UTR) and transduced into SK-N-SH cells to obtain SK-N-SH/FTH1-3xC_miR-21 cells. Then, the antagomiR-21 was delivered into cells by graphene oxide functionalized with polyethylene glycol and dendrimer. Before and after antagomiR-21 delivery, FTH1 expression, MRI contrast and intracellular iron uptake were assayed in vitro and in vivo.

Results

In the SK-N-SH/FTH1-3xC_miR-21 cells, FTH1 expression was in an "off" state due to the combination of intratumoral miR-21 with the 3' UTR of the reporter gene. AntagomiR-21 delivered into the cells bound to miR-21 and thereby released it from the 3' UTR of the reporter gene, thus "switching on" FTH1 expression in a dose-dependent manner. This phenomenon resulted in intracellular iron accumulation and allowed MRI detection in vitro and in vivo.

Conclusion

MRI based on the miR-21-responsive gene reporter may be a potential method for visualization of the endogenous miR-21 activity in neuroblastoma and its response to gene therapy.

SUBMITTER: Bao G

PROVIDER: S-EPMC8602822 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:A library of 10 Mn-containing complexes capable of switching reversibly between the Mn(II) and Mn(III) oxidation states was prepared and evaluated for potential usage as MRI reporters of tissue redox activity. We synthesized N-(2-hydroxybenzyl)-N,N',N'-ethylenediaminetriacetic acid (HBET) and N-(2-hydroxybenzyl-N,N',N'-trans-1,2-cyclohexylenediaminetriacetic acid (CyHBET) ligands functionalized (-H, -OMe, -NO2) at the 5-position of the aromatic ring. The Mn(II) complexes of all ligands and the Mn(III) complexes of the 5-H and 5-NO2 functionalized ligands were synthesized and isolated, but the Mn(III) complexes with the 5-OMe functionalized ligands were unstable. (1)H relaxivity of the 10 isolable complexes was measured at pH 7.4 and 37 °C, 1.4 T. Thermodynamic stability, pH-dependent complex speciation, hydration state, water exchange kinetics of the Mn(II) complexes, and pseudo-first order reduction kinetics of the Mn(III) complexes were studied using a combination of pH-potentiometry, UV-vis spectroscopy, and (1)H and (17)O NMR measurements. The effects of ligand structural and electronic modifications on the Mn(II/III) redox couple were studied by cyclic voltammetry. The Mn(II) complexes are potent relaxation agents as compared to the corresponding Mn(III) species with [Mn(II)(CyHBET)(H2O)](2-) exhibiting a 7.5-fold higher relaxivity (3.3 mM(-1) s(-1)) than the oxidized form (0.4 mM(-1) s(-1)). At pH 7.4, Mn(II) exists as a mixture of fully deprotonated (ML) and monoprotonated (HML) complexes and Mn(II) complex stability decreases as the ligands become more electron-releasing (pMn for 10 ?M [Mn(II)(CyHBET-R')(H2O)](2-) decreases from 7.6 to 6.2 as R' goes from -NO2 to -OMe, respectively). HML speciation increases as the electron-releasing nature of the phenolato-O donor increases. The presence of a water coligand is maintained upon conversion from HML to ML, but the water exchange rate of ML is faster by up to 2 orders of magnitude (k(ex)(310) for H[Mn(II)(CyHBET)(H2O)](-) and [Mn(II)(CyHBET)(H2O)](2-) are 1.2 × 10(8) and 1.0 × 10(10) s(-1), respectively). The Mn(II/III) redox potential can be tuned over a range of 0.30 V (E(1/2) = 0.27-0.57 V) through electronic modifications to the 5-substituent of the aromatic ligand component. However, care must be taken in tuning the ligand electronics to avoid Mn(III)-ligand autoredox. Taken together, these results serve to establish criteria for optimizing Mn(III) versus Mn(II) relaxivity differentials, complex stability, and Mn(II/III) redox potential.