In Vivo Gold Complex Catalysis within Live Mice Tsubokura, Kazuki; Vong, Kenward K. H.; Pradipta, Ambara R. ...
Angewandte Chemie International Edition,
March 20, 2017, Letnik:
56, Številka:
13
Journal Article
Recenzirano
Metal complex catalysis within biological systems is largely limited to cell and bacterial systems. In this work, a glycoalbumin–AuIII complex was designed and developed that enables organ‐specific, ...localized propargyl ester amidation with nearby proteins within live mice. The targeted reactivity can be imaged through the use of Cy7.5‐ and TAMRA‐linked propargyl ester based fluorescent probes. This targeting system could enable the exploitation of other metal catalysis strategies for biomedical and clinical applications.
The first metal‐catalyzed reaction that proceeds within live mice is based on a targeting approach with glycans. Glycoalbumin–AuIII complexes can be accumulated in specific organs where they catalyze amide bond formation between a propargyl ester probe and amine groups on nearby proteins. The selective targeting was confirmed by whole body fluorescence imaging and analysis of dissected tissues.
Considering the intrinsic toxicities of transition metals, their incorporation into drug therapies must operate at minimal amounts while ensuring adequate catalytic activity within complex biological ...systems. As a way to address this issue, this study investigates the design of synthetic prodrugs that are not only tuned to be harmless, but can be robustly transformed in vivo to reach therapeutically relevant levels. To accomplish this, retrosynthetic prodrug design highlights the potential of naphthylcombretastatin-based prodrugs, which form highly active cytostatic agents via sequential ring-closing metathesis and aromatization. Structural adjustments will also be done to improve aspects related to catalytic reactivity, intrinsic bioactivity, and hydrolytic stability. The developed prodrug therapy is found to possess excellent anticancer activities in cell-based assays. Furthermore, in vivo activation by intravenously administered glycosylated artificial metalloenzymes can also induce significant reduction of implanted tumor growth in mice.
In order to harness the functionality of metals, nature has evolved over billions of years to utilize metalloproteins as key components in numerous cellular processes. Despite this, transition metals ...such as ruthenium, palladium, iridium, and gold are largely absent from naturally occurring metalloproteins, likely due to their scarcity as precious metals. To mimic the evolutionary process of nature, the field of artificial metalloenzymes (ArMs) was born as a way to benefit from the unique chemoselectivity and orthogonality of transition metals in a biological setting. In its current state, numerous examples have successfully incorporated transition metals into a variety of protein scaffolds. Using these ArMs, many examples of new-to-nature reactions have been carried out, some of which have shown substantial biocompatibility. Given the rapid rate at which this field is growing, this review aims to highlight some important studies that have begun to take the next step within this field; namely the development of ArM-centered drug therapies or biotechnological tools.
Akin to a cellular “fingerprint,” the glycocalyx is a glycan‐enriched cellular coating that plays a crucial role in mediating cell‐to‐cell interactions. To gain a better understanding of the factors ...that govern in vivo recognition, artificial glycoproteins were initially created to probe changes made to the accumulation and biodistribution of specific glycan assemblies through biomimicry. As a result, the organ‐specific accumulation for a variety of glycoproteins decorated with simple and/or complex glycans was identified. Additionally, binding trends with regard to cancer cell selectivity were also investigated. To exploit the knowledge gained from these studies, numerous groups thus became engaged in developing targeted drug methodologies based on the use of artificial glycoproteins. This has either been done through adopting the glycoprotein scaffold as a drug carrier, or to directly glycosylate therapeutic proteins/enzymes to localize their biological activity. The principle aim of this Review is to present the foundational research that has driven artificial glycoprotein‐based targeting and subsequent adaptations with potential therapeutic applications.
To gain a better understanding of the factors that govern in vivo cellular recognition, artificial glycoproteins are created as biomimetic probes to study the influence of specific glycan assemblies to biodistribution. The principle aim of this Review is to present pioneering research that has driven artificial glycoprotein‐based targeting and subsequent adaptations with potential therapeutic applications.
An emerging approach in the field of targeted drug delivery is the establishment of abiotic metal‐triggered prodrug mechanisms that can control the release of bioactive drugs. Currently, the design ...of prodrugs that use abiotic metals as a trigger relies heavily on uncaging strategies. Here, we introduce a strategy based on the gold‐catalyzed activation of a phenanthridinium‐based prodrug via hydroamination under physiological conditions. To make the prodrug strategy biocompatible, a gold artificial metalloenzyme (ArM) based on human serum albumin, rather than the free gold metal complex, was used as a trigger for prodrug activation. The albumin‐based gold ArM protected the catalytic activity of the bound gold metal even in the presence of up to 1 mM glutathione in vitro. The drug synthesized via the gold ArM exerted a therapeutic effect in cell‐based assays, highlighting the potential usefulness of the gold ArM in anticancer applications.
A gold artificial metalloenzyme catalyzes the conversion of a prodrug into a phenanthridinium‐based anticancer drug with a good turnover number (>100) via hydroamination under mild conditions. The gold artificial metalloenzyme successfully triggers drug synthesis to achieve cancer therapy in cell‐based assays.
Enzyme biosensors are useful tools that can monitor rapid changes in metabolite levels in real-time. However, current approaches are largely constrained to metabolites within a limited chemical ...space. With the rising development of artificial metalloenzymes (ArM), a unique opportunity exists to design biosensors from the ground-up for metabolites that are difficult to detect using current technologies. Here we present the design and development of the ArM ethylene probe (AEP), where an albumin scaffold is used to solubilize and protect a quenched ruthenium catalyst. In the presence of the phytohormone ethylene, cross metathesis can occur to produce fluorescence. The probe can be used to detect both exogenous- and endogenous-induced changes to ethylene biosynthesis in fruits and leaves. Overall, this work represents an example of an ArM biosensor, designed specifically for the spatial and temporal detection of a biological metabolite previously not accessible using enzyme biosensors.
Metal-based uncaging of biomolecules has become an emerging approach for in vivo applications, which is largely due to the advantageous bioorthogonality of abiotic transition metals. Adding to the ...library of metal-cleavable protecting groups, this work introduces the 2-alkynylbenzamide (Ayba) moiety for the gold-triggered release of secondary amines under mild and physiological conditions. Studies were further performed to highlight some intrinsic benefits of the Ayba protecting group, which are (1) its amenable nature to derivatization for manipulating prodrug properties, and (2) its orthogonality with other commonly used transition metals like palladium and ruthenium. With a focus on highlighting its application for anticancer drug therapies, this study successfully shows that gold-triggered conversion of Ayba-protected prodrugs into bioactive anticancer drugs ( i.e. doxorubicin, endoxifen) can proceed effectively in cell-based assays.
This study presents the early framework of selective cell tagging (SeCT) therapy, which is the concept of preferentially labeling specific cells in vivo with chemical moieties that can elicit a ...therapeutic response. Using glycosylated artificial metalloenzyme (GArM)-based protein labeling, this study reports two separate functional strategies. In one approach, early tumor onset can be suppressed by tagging cancer cells in living mice with an integrin-blocking cyclic-Arg-Gly-Asp (cRGD) moiety, thereby disrupting cell adhesion onto the extracellular matrix. In another approach, tumor growth in mice can be reduced by tagging with a cytotoxic doxorubicin moiety. Subsequent cell death occurs following internalization and drug release. Overall, experiments have shown that mouse populations receiving the mixture of SeCT labeling reagents exhibited a significant delay/reduction in tumor onset and growth compared with controls. Highlighting its adaptability, this work represents a foundational step for further development of SeCT therapy and its potential therapeutic applications.
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