Tetraspanins: Physiology, Colorectal Cancer Development, and Nanomediated Applications

Tetraspanins are transmembrane proteins expressed in a multitude of cells throughout the organism. They contribute to many processes that surround cell–cell interactions and are associated with the progress of some diseases, including cancer. Their crucial role in cell physiology is often understated. Furthermore, recent studies have shown their great potential in being used as targeting molecules. Data have suggested the potential of tetraspanins as a targeting vector for nanomediated distribution and delivery for colorectal cancer applications. Our aim is to provide a review on the important part that tetraspanins play in the human organism and highlight their potential use for drug delivery systems using nanotechnology.

Metal–ligand interactions in complexes of cyclen-based ligands with Bi and Ac

The structural and bonding properties of Bi and Ac complexes with cyclen-based chelating ligands have been studied using relativistic DFT calculations in conjunction with TZ2P all-electron basis sets. Besides the parent cyclen ligand, the study has covered its extensions with pyridine-type (Lpy), carboxylate (DOTA, DOTPA), picolinate (MeDO2PA) and phosphonate (DOTMP) pendant arms. The effect of the cyclen ring size has been probed by increasing it from [12]aneN4 to [16]aneN4. Additional extensions in the DOTA complexes included the H2O ligand at the 9th coordination site as well as the p-SCN-Bn substituent (a popular linker to the targeting vector). The study focuses on the complex stability, the nature of bonding and the differences between Ac and Bi in the complexes. The metal–ligand interactions have been analysed by the Extended Transition State method combined with Natural Orbitals of Chemical Valence theory and Quantum Theory of Atoms in Molecules models.

A Rapid and Highly Efficient Genotyping Pipeline for Screening Gene Targeted Mouse Embryonic Stem Cells

Gene targeting in mouse ES cells replaces or modifies genes of interest; conditional alleles, reporter knock-ins, and amino acid changes are common examples of how gene targeting is used. For example, enhanced green fluorescent protein or Cre recombinase is placed under the control of endogenous genes to define promoter expression patterns. The most important step in the process is to demonstrate that a gene targeting vector is correctly integrated in the genome at the desired chromosomal location. The rapid identification of correctly targeted ES cell clones is facilitated by proper targeting vector construction, rapid screening procedures, and advances in cell culture. The addition of magnetic activated cell sorting (MACS) technology and multiplex droplet digital PCR (ddPCR) to the ES cell screening process can achieve a greater than 60% assurance that ES clones are correctly targeted. In a further refinement of the process, drug selection cassettes are removed from ES cells with adenovirus technology. This improved workflow reduces the time needed to generate preclinical animal models. Faster access to animal models for therapeutic target identification and experimental validation can accelerate the development of therapies for human disease.

Pretargeted Theranostics

Personalized medicine is becoming an integral part of our healthcare system, in which theranostics play a fundamental role. Nanomedicines such as monoclonal antibodies are a commonly used targeting vector in such approaches due to their outstanding targeting abilities as well as their capabilities to function as drug delivery vehicles. However, the application of nanomedicines in a clinical setting is connected with several challenges. For example, nanomedicines typically possess slow pharmacokinetics in respect to target accumulation and excretion. For targeted radionuclide therapy, this results in high radiation burden to healthy tissue. For drug delivery systems, long circulation and excretion times of the nanomedicine complicate site-specific release approaches and limit as such the usability of these strategies. One way to circumvent these challenges is the use of pretargeting strategies, which allow to separate the accumulation and excretion of nanomedicines from the actual diagnostic or therapeutic application. As such, pretargeting allows to use theranostic concepts utilizing the same nanomedicine and determine the success chances with diagnostic measures before initiating therapy. This chapter will explain the concept of pretargeted theranostics, which pretargeting systems have thus far been developed and compare how these systems performed.

Selective delivery of remarkably high levels of gadolinium to tumour cells using an arsonium salt

A triphenylarsonium targeting vector is far superior to the well-established, isosteric phosphonium analogue for tumour cell delivery of Gd3+.

Drug Conjugates Based on a Monovalent Affibody Targeting Vector Can Efficiently Eradicate HER2 Positive Human Tumors in an Experimental Mouse Model

The human epidermal growth factor receptor 2 (HER2) is frequently overexpressed in a variety of cancers and therapies targeting HER2 are routinely used in the clinic. Recently, small engineered scaffold proteins, such as affibody molecules, have shown promise as carriers of cytotoxic drugs, and these drug conjugates may become complements or alternatives to the current HER2-targeting therapies. Here, we investigated if a monovalent HER2-binding affibody molecule, ZHER2:2891, fused with a plasma half-life extending albumin binding domain (ABD), may be used as carrier of the cytotoxic maytansine derivate mcDM1. We found that the resulting drug conjugate, ZHER2:2891-ABD-E3-mcDM1, had strong affinity for its cognate molecular targets: HER2 and serum albumin. ZHER2:2891-ABD-E3-mcDM1 displayed potent cytotoxic activity towards cells with high HER2 expression, with IC50 values ranging from 0.6 to 33 nM. In vivo, an unspecific increase in uptake in the liver, imparted by the hydrophobic mcDM1, was counteracted by incorporation of hydrophilic and negatively charged glutamate residues near the site of mcDM1 conjugation. A dose-escalation experiment showed that increasing doses up to 15.1 mg/kg gave a proportional increase in uptake in xenografted HER2-overexpressing SKOV3 tumors, after which the tumors became saturated. Experimental therapy with four once-weekly injection of 10.3 or 15.1 mg/kg led to efficient regression of tumors in all animals and complete regression in some. Weight loss was detected for some animals in the group receiving the highest dose, suggesting that it was close to the maximum tolerated dose. In conclusion, the monovalent HER2-targeting affibody drug conjugate presented herein have potent anti-tumor activity in vivo.

A simple method using CRISPR-Cas9 to knock-out genes in murine cancerous cell lines

CRISPR-Cas9 system can be used to generate knock-out cancer cell lines. An insertion or deletion induced by a single guide RNA (gRNA) is often used to generate knock-out cells, however, some cells express the target gene by skipping the disrupted exon, or by using a splicing variant, thus losing the target exon. To overcome this unexpected expression of the target gene, almost the entire gene can be swapped with a selection marker. However, it is time-consuming to create a targeting vector which contains 5′ and 3′ homology arms flanked by a selection marker. Here, we developed a simple and easy method called SUCCESS (Single-strand oligodeoxynucleotides, Universal Cassette, and CRISPR/Cas9 produce Easy Simple knock-out System), to knock-out a target gene without constructing a targeting vector. Our method removed the targeted large genomic region by using two pX330 plasmids encoding Cas9 and gRNA, two 80mer single strand oligodeoxynucleotides (ssODN), and a blunt-ended universal selection maker sequence in B16F10 murine cancer cell and ID8 murine ovarian cancer cell. SUCCESS generated knock-out clones in two murine cancer cell lines by homozygous deletion of the target genomic region, and without constructing targeting vectors. Thus, our method can be widely applied to generate homozygous knock-out cell lines, as well as knock-in cell lines.

P0859ACTIVATE ENDOGENOUS HYDROXYMETHYLATION TO RESTORE ERYTHROPOIETIN PRODUCTION IN FIBROTIC KIDNEYS

Background and Aims Our previous studies have shown that DNA methyltransferases (Dnmt) and Epo hypermethylation are upregulated in myofibroblasts in fibrotic murine kidneys. Demethylation leads to redifferentiation of myofibroblasts into pericytes. Furthermore, nontoxic doses of 5-azacytidine can restore EPO production and ameliorate anemia in mice with kidney fibrosis. Physiologic hydroxymethylation in zygotes is mediated by the 10 − 11 translocation enzymes (Tet1, Tet2, and Tet3). Method The mouse model of unilateral ureteral obstruction (UUO)-induced kidney fibrosis has been found to display enhanced Tet1 and Tet3 mRNA expression at day 7 and marked increase with the disease progression. Results According to the results, Tet expression significantly increased in fibrotic kidney. To study the effect of myofibroblast-specific Tet3 knockout in murine models of renal fibrosis. Tet3F/F mice were generated by a targeting vector with floxed region contains exons 8-9 of Tet3, which included the coding region for the conserved Fe2+-binding motif of dioxygenase. Gli1CreERT2/+;Tet3F/F mice were used to induce knockout of Tet3 in pericytes and myofibroblasts after tamoxifen administration. Tet3F/F mice were used as the control. Oral gavage of tamoxifen 8 mg/day for 3 days was used to activate Cre recombinase in Gli1+ pericytes and myofibroblasts in adult mice (6-8 week). After two-week washout period, mice were subjected to UUO for 7 or 14 days. The body weight, plasma creatinine and BUN levels showed no significant differences between groups in mice after induction and also UUO surgery. Plasma levels of BUN and creatinine were maintained within the normal range by normally functioning contralateral kidneys after UUO surgery. In UUO kidneys, knockout of Tet3 decreased renal α-SMA and Col1a1 expression. But plasma hematocrit and renal Epo mRNA level were not different between groups. In addition to Gli1CreERT2/+ mice we also used Pdgfrb-rtTATg;LC1Tg mice to breed with Tet3F/F mice for inducible knockout of Tet3. The plasma creatinine, BUN, and hematocrit were no different between groups after UUO surgery again. Conclusion Overall, these findings suggested increased Tet3 in myofibroblasts may play an important role in myofibroblast activation and fibrosis. Further studies need to explore the mechanisms.