Cell penetrating peptide of sodium-iodide symporter effect on the I-131 radiotherapy on thyroid cancer

Poly (lactic-co-glycolic acid)-encapsulated iodine-131 nanoparticles fabricated with rhTSH induce apoptosis and immobilization of thyroid cancer cells

Background

Aggressive thyroid carcinoma (ATC) usually loses radioiodine avidity to iodine-131 (¹³¹I) due to the downregulation of sodium/iodide symporter (NIS). The expression of thyroid stimulating hormone receptor (TSHR) is more persistent than NIS and the administration of recombinant human thyroid stimulating hormone (rhTSH) promotes de novo NIS synthesis. Hence, exploring methods integrating ¹³¹I with rhTSH might be a feasible therapeutic strategy for selective delivery of ¹³¹I into thyroid cancer to fortify the effect of radioiodine ablation.

Methods

The ¹³¹I, poly (lactic-co-glycolic acid) (PLGA) and rhTSH were used to synthesize of the ¹³¹I-PLGA-rhTSH nanoparticles. The characteristics of the ¹³¹I-PLGA-rhTSH nanoparticles was determined using a light microscopy, scanning electron microscopy (SEM), autoradiography and immunofluorescence (IF) staining. The diameter of the ¹³¹I-PLGA-rhTSH nanoparticles was measured with a Mastersizer 3000, and the encapsulation efficiency (EF) of ¹³¹I in ¹³¹I-PLGA-rhTSH nanoparticles and the radioactivity of a single nanoparticle were determined. Then, the mouse tumor xenograft model was established, and the biodistribution and effect of ¹³¹I-PLGA-rhTSH nanoparticles on apoptosis of thyroid cance cells were investigated in vivo. Thereafter, the role of ¹³¹I-PLGA-rhTSH nanoparticles in cell viability using cell counting kit-8 and lactate dehydrogenase (LDH) release assays. Subsequently, the underlying mechanism of ¹³¹I-PLGA-rhTSH nanoparticles in reducing cell viability was assessed using immunostaining, boyden invasion assays and phalloidin staining.

Results

Our results showed that the method of developing nanoparticles-encapsulated ¹³¹I using poly (lactic-co-glycolic acid) (PLGA) and modified with rhTSH (¹³¹I-PLGA-rhTSH), was a feasible avenue for the integration of ¹³¹I and rhTSH. Meanwhile, the encapsulation efficiency (EF) of ¹³¹I-PLGA-rhTSH nanoparticles was approximately 60%, and the radioactivity of a single nanoparticle was about 1.1×10-2 Bq. Meanwhile, the ¹³¹I-PLGA-rhTSH nanoparticles were selectively delivered into, gradually enriched and slowly downregulated in xenograft tumor after the administration of ¹³¹I-PLGA-rhTSH nanoparticles through tail vein in mouse tumor xenograft model. Thereafter, the tumor weight was significantly reduced after the administration of ¹³¹I-PLGA-rhTSH nanoparticles. Subsequently, the application of ¹³¹I-PLGA-rhTSH nanoparticles facilitated apoptosis and attenuated immobilization via inhibiting F-actin assembling of FTC-133 cells.

Conclusion

The present study develops a suitable approach integrating ¹³¹I and rhTSH, and this strategy is a feasible regimen enhancing the effect of radioiodine ablation for the treatment of thyroid cancer.

Delivery of Active AKT1 to Human Cells

Protein kinase B (AKT1) is a serine/threonine kinase and central transducer of cell survival pathways. Typical approaches to study AKT1 biology in cells rely on growth factor or insulin stimulation that activates AKT1 via phosphorylation at two key regulatory sites (Thr308, Ser473), yet cell stimulation also activates many other kinases. To produce cells with specific AKT1 activity, we developed a novel system to deliver active AKT1 to human cells. We recently established a method to produce AKT1 phospho-variants from Escherichia coli with programmed phosphorylation. Here, we fused AKT1 with an N-terminal cell penetrating peptide tag derived from the human immunodeficiency virus trans-activator of transcription (TAT) protein. The TAT-tag did not alter AKT1 kinase activity and was necessary and sufficient to rapidly deliver AKT1 protein variants that persisted in human cells for 24 h without the need to use transfection reagents. TAT-pAKT1^T308 induced selective phosphorylation of the known AKT1 substrate GSK-3α, but not GSK-3β, and downstream stimulation of the AKT1 pathway as evidenced by phosphorylation of ribosomal protein S6 at Ser240/244. The data demonstrate efficient delivery of AKT1 with programmed phosphorylation to human cells, thus establishing a cell-based model system to investigate signaling that is dependent on AKT1 activity.

Research Progress of nucleic acid delivery vectors for gene therapy

Gene therapy has broad prospects as an effective treatment for some cancers and hereditary diseases. However, DNA and siRNA are easily degraded in vivo because of their biological activities as macromolecules, and they need the effective transmembrane delivery carrier Selecting the appropriate carrier for delivery will allow nucleic acid molecules to reach their site of action and enhance delivery efficiency. Currently used nucleic acid delivery vectors can be divided into two major categories: viral and non-viral vectors. Viral carrier transport efficiency is high, but there are safety issues. Non-viral vectors have attracted attention because of their advantages such as low immunogenicity, easy production, and non-tumorigenicity. The construction of safe, effective, and controllable vectors is the focus of current gene therapy research. This review presents the current types of nucleic acid delivery vehicles, which focuses on comparing their respective advantages and limitations, and proposes a novel delivery system, RNTs, a novel nanomolecular material, introducing the characteristics and nucleic acid delivery process of RNTs and their latest applications.

1988-2018: Thirty years of drug smuggling at the nano scale. Challenges and opportunities of cell-penetrating peptides in biomedical research

In 1988, two unrelated papers reported the discovery of peptide vectors with innate cell translocation properties, setting the ground for a new area of research that over the years has grown into considerable therapeutic potential. The vectors, named cell-penetrating peptides (CPPs), constitute a now large and diversified family, sharing the extraordinary ability to diffuse unaltered across cell membranes while ferrying diverse associated cargos. Such properties have made CPPs ideal tools for delivery of nucleic acids, proteins and other therapeutic/diagnostic molecules to cells and tissues via covalent conjugation or complexation. This year 2018 marks the 30^th anniversary of a peptide research landmark opening new perspectives in drug delivery. Given its vastness, exhaustive coverage of the main features and accomplishments in the CPP field is virtually impossible. Hence this manuscript, after saluting the above 30^th jubilee, focuses by necessity on the most recent contributions, providing a comprehensive list of recognized CPPs and their latest-reported applications over the last two years. In addition, it thoroughly reviews three areas of peptide vector research of particular interest to us, namely (i) efficient transport of low-bioavailability drugs into the brain; (ii) CPP-delivered disruptors of G protein-coupled receptor (GPCRs) heteromers related to several disorders, and (iii) CPP-mediated delivery of useful but poorly internalized drugs into parasites.