Development and evaluation of a new modular nanotransporter for drug delivery into nuclei of pathological cells expressing folate receptors

Abstract

PurposeModular nanotransporters (MNTs) are artificial multifunctional systems designed to facilitate receptor-specific transport from the cell surface into the cell nucleus through inclusion of polypeptide domains for accomplishing receptor binding and internalization, as well as sequential endosomal escape and nuclear translocation. The objective of this study was to develop a new MNT targeted at folate receptors (FRs) for precise delivery of therapeutic cargo to the nuclei of FR-positive cells and to evaluate its potential, particularly for delivery of therapeutic agents (eg, the Auger electron emitter 111In) into the nuclei of target cancer cells.MethodsA FR-targeted MNT was developed by site-specific derivatization of ligand-free MNT with maleimide-polyethylene glycol-folic acid. The ability of FR-targeted MNT to accumulate in target FR-expressing cells was evaluated using flow cytometry, and intracellular localization of this MNT was assessed using confocal laser scanning microscopy of cells. The cytotoxicity of the 111In-labeled FR-targeted MNT was evaluated on HeLa and U87MG cancer cell lines expressing FR. In vivo micro-single-photon emission computed tomography/CT imaging and antitumor efficacy studies were performed with intratumoral injection of 111In-labeled FR-targeted MNT in HeLa xenograft-bearing mice.ResultsThe resulting FR-targeted MNT accumulated in FR-positive HeLa cancer cell lines specifically and demonstrated the ability to reach its target destination – the cell nuclei. 111In-labeled FR-targeted MNT demonstrated efficient and specific FR-positive cancer cell eradication. A HeLa xenograft in vivo model revealed prolonged retention of 111In delivered by FR-targeted MNT and significant tumor growth delay (up to 80% growth inhibition).ConclusionThe FR-targeted MNT met expectations of its ability to deliver active cargo into the nuclei of target FR-positive cells efficiently and specifically. As a result of this finding the new FR-targeted MNT approach warrants broad evaluation.

Targeted Delivery of 111In Into the Nuclei of EGFR Overexpressing Cells via Modular Nanotransporters With Anti-EGFR Affibody

“…As 111 In Auger electrons have extremely short ranges, their cytotoxicity was highest when they were localized in the nucleus (Li et al, 2015;Slastnikova et al, 2017a). Thus, we measured the ability of 111 In-NOTA-MNT to accumulate in the nuclei.…”

“…Labeling MNT With 111 In Using p-SCN-Bn-NOTA MNT C-EGF , MNT N-affibody , and MNT N-EGF were labeled in accordance with a previously published protocol (Slastnikova et al, 2017a). MNT were incubated with 10-fold molar excess of the bifunctional p-SCN-Bn-NOTA chelator in conjugation carbonate buffer at pH 8.6 (Hens et al, 2009) for 20 h at room temperature with final concentrations of MNT ≥1.5 mg/ml.…”

Subcellular Targeting of Theranostic Radionuclides

“…They showed superior uptake and cytotoxicity over 67 Ga-hEGF, which was attributed to improved nuclear retention. This MNT has been used with various other ligand modules (melanocortin receptor and folate receptor ligands) and radionuclides ( 111 In, 125 I) ( Slastnikova et al, 2012 , 2017a , b ), and has recently been reviewed by Sobolev (2018) .…”

Modular Nanotransporters for Nuclear-Targeted Delivery of Auger Electron Emitters

“…Following intratumoral administration of folate-MNT- 111 In, normal tissues showed low radioactivity, which was mostly limited to liver and kidney (Slastnikova et al, 2017b). Intratumoral (B16F1 melanoma, C57BL/6J mice) retention of intratumorally injected 111 In-DTox-HMP-NLS-MSH was even better: 3.7 days as fitted to a single exponential.…”