Targeting of EGF-displayed protein nanoparticles with anticancer drugs

Sensitive Detection of Tumor Cells Using Protein Nanoparticles with Multiple Displays of DNA Aptamers and Bioluminescent Reporters

Simple and effective detection methods for circulating tumor cells are essential for early detection and progression monitoring of tumors. The use of DNA aptamer and bioluminescence is expected to be a key tool for the simple, effective, and sensitive detection of tumor cells. Herein, we designed multifunctional protein nanoparticles for the detection of tumor cells using DNA aptamer and bioluminescence. Fusion proteins (ELP-poly(d)-POIs), composed of elastin-like polypeptide (ELP) fused with protein of interests (POIs) via poly(aspartic acid) (poly(d)), formed the protein nanoparticles based on the temperature responsivity of ELP sequences, leading to multiply displayed POIs on the protein nanoparticles. In the present study, we focused on porcine circovirus type 2 replication initiation protein (Rep), which covalently conjugated with DNA aptamers, and NanoLuc luciferase (Nluc), which emitted a strong bioluminescence, as POIs. ELP-poly(d)-Rep and ELP-poly(d)-Nluc were constructed and formed the protein nanoparticles with multiply displayed Nluc and Rep (DNA aptamer) that amplified the bioluminescence signal and tumor recognition ability. Mucin-1 (MUC1)-overexpressing human breast tumor MCF7 cells and MUC1-recognizing aptamer (MUC1 aptamer) were selected as models. The MUC1 aptamer-conjugated protein nanoparticles exhibited a 13.7-fold higher bioluminescence signal to MCF-7 cells than to human embryonic kidney 293 (HEK293) cells, which express low levels of MUC1. Furthermore, the protein nanoparticles could detect up to 70.7 cells/mL of MCF-7 cells from a cell suspension containing HEK-293. The protein nanoparticles with multiple Rep and Nluc show a great potential as a material for detecting CTCs.

Engineered elastin-like polypeptides: An efficient platform for enhanced cancer treatment

Drug delivery systems (DDSs) have recently gained widespread attention for improving drug loading and delivery efficiency in treating many cancers. Elastin-like polypeptides (ELPs) are synthetic peptides derived from a precursor of elastin (tropoelastin), reserving similar structural and physicochemical properties. ELPs have gained a variety of applications in tissue engineering and cancer therapy due to their excellent biocompatibility, complete degradability, temperature-responsive property, controllable sequence and length, and precisely tuned structure and function. ELPs-based drug delivery systems can improve the pharmacokinetics and biodistribution of therapeutic reagents, leading to enhanced antitumor efficacy. In this review, we summarize the recent application of ELPs in cancer treatment, focusing on the delivery of functional peptides, therapeutic proteins, small molecule drugs, and photosensitizers.

Emerging opportunities in bioconjugates of Elastin-like polypeptides with synthetic or natural polymers

Nature is an everlasting source of inspiration for chemical and polymer scientists seeking to develop ever more innovative materials with greater performances. Natural structural proteins are particularly scrutinized to design biomimetic materials. Often characterized by repeat peptide sequences, that together interact by inter- and intramolecular interactions and form a 3D skeleton, they contribute to the mechanical properties of individual cells, tissues, organs, and whole organisms. (Numata, K. Polymer Journal 2020, 52, 1043-1056) Among them elastin, and its main repeat sequences, have been a source of intense studies for more than 50 years resulting in the specific research field dedicated to elastin-like polypeptides (ELPs). These are currently widely investigated in different applications, namely protein purification, tissue engineering, and drug delivery, and some technologies based on ELPs are currently explored by several start-up companies. In the present review, we have summarized pioneering contributions on ELPs, progress made in their genetic engineering, and understanding of their thermal behavior and self-assembly properties. Considered as intrinsically disordered protein polymers, we have finally focused on the works where ELPs have been conjugated to other synthetic macromolecules as covalent hybrid, statistical, graft, or block copolymers, highlighting the huge opportunities that have still not been explored so far.

Application of Elastin-Like Polypeptide in Tumor Therapy

Simple Summary

Elastin-like Polypeptide (ELP) are widely applied in protein purification, drug delivery, tissue engineering, and even tumor therapy. Recent studies show that usage of ELP has made great progress in combination with peptide drugs or antibody drugs. The combination of ELP and photosensitizer in cancer therapy or imaging has made more progress and needs to be summarized. In this review, we summarize the specific application of ELP in cancer therapy, especially the latest developments in the combined use of ELP with photosensitizers. We seek to provide the most recent understanding of ELP and its new application in combination with Photosensitizer.

Abstract

Elastin-like polypeptides (ELPs) are stimulus-responsive artificially designed proteins synthesized from the core amino acid sequence of human tropoelastin. ELPs have good biocompatibility and biodegradability and do not systemically induce adverse immune responses, making them a suitable module for drug delivery. Design strategies can equip ELPs with the ability to respond to changes in temperature and pH or the capacity to self-assemble into nanoparticles. These unique tunable biophysicochemical properties make ELPs among the most widely studied biopolymers employed in protein purification, drug delivery, tissue engineering and even in tumor therapy. As a module for drug delivery and as a carrier to target tumor cells, the combination of ELPs with therapeutic drugs, antibodies and photo-oxidation molecules has been shown to result in improved pharmacokinetic properties (prolonged half-life, drug targeting, cell penetration and controlled release) while restricting the cytotoxicity of the drug to a confined infected site. In this review, we summarize the latest developments in the application methods of ELP employed in tumor therapy, with a focus on its conjugation with peptide drugs, antibodies and photosensitizers.

Elastin-like Polypeptides in Development of Nanomaterials for Application in the Medical Field

Elastin-like polypeptides (ELPs) are biopolymers formed by amino acid sequences derived from tropoelastin. These biomolecules can be soluble below critical temperatures, forming aggregates at higher temperatures, which makes them an interesting source for the design of different nanobiomaterials. These nanobiomaterials can be obtained from heterologous expression in several organisms such as bacteria, fungi, and plants. Thanks to the many advantages of ELPs, they have been used in the biomedical field to develop nanoparticles, nanofibers, and nanocomposites. These nanostructures can be used in multiple applications such as drug delivery systems, treatments of type 2 diabetes, cardiovascular diseases, tissue repair, and cancer therapy. Thus, this review aims to shed some light on the main advances in elastin-like-based nanomaterials, their possible expression forms, and importance to the medical field.

Engineered protein nanodrug as an emerging therapeutic tool

Functional proteins are the most versatile macromolecules. They can be obtained by extraction from natural sources or by genetic engineering technologies. The outstanding selectivity, specificity, binding activity, and biocompatibility endow engineered proteins with outstanding performance for disease therapy. Nevertheless, their stability is dramatically impaired in blood circulation, hindering clinical translations. Thus, many strategies have been developed to improve the stability, efficacy, bioavailability, and productivity of therapeutic proteins for clinical applications. In this review, we summarize the recent progress in the fabrication and application of therapeutic proteins. We first introduce various strategies for improving therapeutic efficacy via bioengineering and nanoassembly. Furthermore, we highlight their diverse applications as growth factors, nanovaccines, antibody-based drugs, bioimaging molecules, and cytokine receptor antagonists. Finally, a summary and perspective for the future development of therapeutic proteins are presented.

Construction of DNA-displaying nanoparticles by enzymatic conjugation of DNA and elastin-like polypeptides using a replication initiation protein

DNA-displaying nanoparticles comprised of conjugates of single-stranded DNA (ssDNA) and elastin-like polypeptide (ELP) were developed. ssDNA was enzymatically conjugated to ELPs via a catalytic domain of Porcine Circovirus type 2 replication initiation protein (pRep) fused to ELPs. Nanoparticles were formed upon heating to temperatures above the phase transition temperature due to the hydrophobicity of ELPs and the hydrophilicity of conjugated ssDNA. We demonstrated the applicability of the resultant nanoparticles as drug carriers with tumor-targeting properties by conjugating a DNA aptamer, which is known to bind to Mucin 1 (MUC1), to ELPs. DNA aptamer-displaying nanoparticles encapsulating the anti-cancer drug paclitaxel were able to bind to cells overexpressing MUC1 and induce cell death.

Temperature-Responsive Multifunctional Protein Hydrogels with Elastin-like Polypeptides for 3-D Angiogenesis

Supramolecular protein hydrogels with tunable properties represent promising candidates for advanced designer extracellular matrices (ECMs). To control cellular functions, ECMs should be able to spatiotemporally regulate synergistic signaling between transmembrane receptors and growth factor (GF) receptors. In this study, we developed genetically engineered temperature-responsive multifunctional protein hydrogels. The designed hydrogel was fabricated by combining the following four peptide blocks: thermosensitive elastin-like polypeptides (ELPs), a polyaspartic acid (polyD) chain to control aggregation and delivery of GFs, a de novo-designed helix peptide that forms antiparallel homotetrameric coiled-coils, and a biofunctional peptide. The resultant coiled-coil unit bound ELPs (CUBEs) exhibit a controllable sol-gel transition with tunable mechanical properties. CUBEs were functionalized with bone sialoprotein-derived RGD (bRGD), and human umbilical vein endothelial cells (HUVECs) were three-dimensionally cultured in bRGD-modified CUBE (bRGD-CUBE) hydrogels. Proangiogenic activity of HUVECs was promoted by bRGD. Moreover, heparin-binding angiogenic GFs were immobilized to bRGD-CUBEs via electrostatic interactions. HUVECs cultured in GF-tethered bRGD-CUBE hydrogels formed three-dimensional (3-D) tubulelike structures. The designed CUBE hydrogels may demonstrate utility as advanced smart biomaterials for biomedical applications. Further, the protein hydrogel design strategy may provide a novel platform for constructing designer 3-D microenvironments for specific cell types.

Development of drug-loaded protein nanoparticles displaying enzymatically-conjugated DNA aptamers for cancer cell targeting

Modification of protein-based drug carriers with tumor-targeting properties is an important area of research in the field of anticancer drug delivery. To this end, we developed nanoparticles comprised of elastin-like polypeptides (ELPs) with fused poly-aspartic acid chains (ELP-D) displaying DNA aptamers. DNA aptamers were enzymatically conjugated to the surface of the nanoparticles via genetic incorporation of Gene A* protein into the sequence of the ELP-D fusion protein. Gene A* protein, derived from bacteriophage ϕX174, can form covalent complexes with single-stranded DNA via the latter's recognition sequence. Gene A* protein-displaying nanoparticles exhibited the ability to deliver the anticancer drug paclitaxel (PTX), whilst retaining activity of the conjugated Gene A* protein. PTX-loaded protein nanoparticles displaying DNA aptamers known to bind to the MUC1 tumor marker resulted in increased cytotoxicity with MCF-7 breast cancer cells compared to PTX-loaded protein nanoparticles without the DNA aptamer modification.

Peptide and protein nanoparticle conjugates: versatile platforms for biomedical applications

Peptide- and protein-nanoparticle conjugates have emerged as powerful tools for biomedical applications, enabling the treatment, diagnosis, and prevention of disease. In this review, we focus on the key roles played by peptides and proteins in improving, controlling, and defining the performance of nanotechnologies. Within this framework, we provide a comprehensive overview of the key sequences and structures utilised to provide biological and physical stability to nano-constructs, direct particles to their target and influence their cellular and tissue distribution, induce and control biological responses, and form polypeptide self-assembled nanoparticles. In doing so, we highlight the great advances made by the field, as well as the challenges still faced in achieving the clinical translation of peptide- and protein-functionalised nano-drug delivery vehicles, imaging species, and active therapeutics.

Nanoparticles combined with growth factors: recent progress and applications

Increasing attention has been focused on the applications of nanoparticles combined with growth factors (NPs/GFs) due to the substantial functions of GFs in regenerative medicine and disease treatments.

Design of luciferase-displaying protein nanoparticles for use as highly sensitive immunoassay detection probes

In this study, we developed a protein nanoparticle-based immunoassay to detect cancer biomarkers using a bioluminescent fusion protein.

Growth Factor Tethering to Protein Nanoparticles via Coiled-Coil Formation for Targeted Drug Delivery

Protein-based nanoparticles are attractive carriers for drug delivery because they are biodegradable and can be genetically designed. Moreover, modification of protein-based nanoparticles with cell-specific ligands allows for active targeting abilities. Previously, we developed protein nanoparticles comprising genetically engineered elastin-like polypeptides (ELPs) with fused polyaspartic acid tails (ELP-D). Epidermal growth factor (EGF) was displayed on the surface of the ELP-D nanoparticles via genetic design to allow for active cell-targeting abilities. Herein, we focused on the coiled-coil structural motif as a means for noncovalent tethering of growth factor to ELP-D. Specifically, two peptides known to form a heterodimer via a coiled-coil structural motif were fused to ELP-D and single-chain vascular endothelial growth factor (scVEGF121), to facilitate noncovalent tethering upon formation of the heterodimer coiled-coil structure. Drug-loaded growth factor-tethered ELP-Ds were found to be effective against cancer cells by provoking cell apoptosis. These results demonstrate that tethering growth factor to protein nanoparticles through coiled-coil formation yields a promising biomaterial candidate for targeted drug delivery.