Overcoming Non-Specific Interactions for Efficient Encapsulation of Doxorubicin in Ferritin Nanocages for Targeted Drug Delivery

5-FU@HFn combined with decitabine induces pyroptosis and enhances antitumor immunotherapy for chronic myeloid leukemia

BACKGROUND

Tyrosine kinase inhibitors (TKIs) constitute the primary treatment for chronic myeloid leukemia (CML). However, resistance to TKIs often leads to treatment failure. Pyroptosis, a form of programmed cell death, has emerged as a promising strategy in cancer therapy due to its ability to eliminate tumor cells while stimulating antitumor immunity. Low-dose decitabine (DAC) has been shown to reverse methylation-induced silencing of the pyroptosis-related gene gasdermin E (GSDME) in some tumor cells, offering a potential new therapeutic option for CML. Herein, we propose a combination therapy using 5-fluorouracil (5-FU), a broad-spectrum chemotherapeutic agent, and low-dose DAC to induce pyroptosis in CML cells via the caspase-3/GSDME pathway. However, the nonspecific targeting of 5-FU diminishes its pyroptosis efficacy and causes off-target toxicity, highlighting the need for a targeted drug delivery system.

RESULTS

In this study, we developed 5-FU@HFn nanoparticles (NPs) by loading 5-FU into the recombinant human heavy chain ferritin (HFn) nanocage through a high-temperature via the drug channels on the protein cage. The loading efficiency was approximately 50.62 ± 1.17 µg of 5-FU per mg of HFn. 5-FU@HFn NPs selectively targeted CML cells through CD71-mediated uptake, significantly enhancing the therapeutic effects of 5-FU. When combined with DAC, 5-FU@HFn NPs effectively activated pyroptosis via the caspase-3/GSDME pathway in both TKI-sensitive and TKI-resistant CML cells. In a CML mouse model, this combination therapy significantly suppressed tumorigenesis and triggered a robust antitumor immune response, facilitating the clearance of leukemic cells. Furthermore, the 5-FU@HFn NPs exhibited excellent in vivo safety.

CONCLUSIONS

The innovative therapeutic strategy, combining 5-FU@HFn nanoparticles with low-dose DAC, effectively induces caspase-3/GSDME-mediated pyroptosis and activates antitumor immunity for CML. This approach offers a potential alternative for patients resistant or intolerant to TKIs.

Systematic probing of protein adsorption on protein-based nanoparticles in dependence of the particle surface charge

Understanding protein adsorption on the surface of nanoparticles (NPs) is crucial for determining their behavior in biological environments. Early research in this field faced challenges in producing high-quality NPs. Advancements in NP fabrication now allow for precise modifications of specific parameters, such as zeta potential. However, creating a series of NPs where only one parameter, such as surface charge, is independently varied remains challenging due to concurrent alterations in other properties. In this study, we address these challenges using the ferritin nanocage (Ftn) as a model system for NPs. By modifying only a few amino acids on the outer surface of Ftn, we produce NPs with highly defined properties, focusing solely on variations in surface charge. This approach enables us to generate a controlled series of protein-based nanocages, labeled with fluorophores inside the nanocage. We utilize fluorescent correlation spectroscopy (FCS) to investigate the adsorption of bovine serum albumin (BSA) on these NPs, analyzing the dependence of BSA binding on surface charge. This fundamental study enhances our understanding of the driving forces behind protein adsorption, contributing valuable insights into the design of NPs for biomedical applications.

Construction of robust protein nanocage by designed disulfide bonds for active cargo molecules protection in the gastric environment

Notwithstanding the progress made, cargo molecules encapsulated within ferritin via oral administration in the gastric environment remains a persistent challenge. This study focuses on the strategic enhancement of ferritin stability in harsh gastric environment. By taking advantagie of computational-assisted design, we strategically introduced up to 96 disulfide bonds along three key inter-subunit interfaces to one single ferritin molecule with human H-chain ferritin and shrimp (Marsupenaeus japonicus) ferritin as starting materials, producing two kinds of robust ferritin nanocages with markedly enhanced acid and protease (pepsin and rennin) resistance. The crystal structure of ferritin nanocage confirmed our design at an atomic level. Encapsulation experiments demonstrated successful loading of bioactive cargo molecules (e.g., doxorubicin) into the engineered ferritin nanocages, with pronouncedly improved protection against leakage under acidic condition and the presence of pepsin and rennin as compared to their native counterparts. This study presents a potential approach for the design and engineering of protein nanocages for oral administration.

Unlocking Nature's Potential: Ferritin as a Universal Nanocarrier for Amplified Cancer Therapy Testing via 3D Microtissues

In the existing development of extensive drug screening models, 3D cell cultures outshine conventional 2D monolayer cells by closely imitating the in vivo tumor microenvironment. This makes 3D culture a more physiologically relevant and convenient system in the regime of preclinical drug testing. In the nanomedicinal world, nanoconjugates as nanocarriers are largely hunted due to their capability of precisely binding to target cells and distributing essential dosages of therapeutic drugs with enhanced safety profiles. Thus, for boosted drug availability, the evolution from conventional drug treatment to combination therapies and last switching to drug carriers has gained significant progression in cancer cure. In contrast to conventional engineered nanoparticles, herein, we successfully designed biomolecule (ferritin)-based drug nanoconjugates effective both as a single drug (valproic acid-VPA) and twin-drug (valproic acid/doxorubicin-Dox) carriers, which dramatically enhance the proficiency of the tumor therapeutic modality. To question the reported adjuvant drug property of VPA, we progressed utilizing at first VPA alone as an effective yet exclusive tumor therapy when delivered via some carrier molecule, in particular protein. Subsequently, we paralleled this comprehensive investigation output to compare and test the coloading strategy of drugs and observe the synergistic and/or additive behavior of VPA in conjugation with other anticancer agents (Dox) while given via a carrier molecule. To approach this, VPA and/or Dox molecules were encapsulated into the ferritin (F) cavity using a thermosensitive synthesis method by maintaining the temperature at 60 °C. The successful encapsulation of drugs in the protein nanocage was confirmed through various characterization techniques. The F-VPA/F-VPA-Dox nanoconjugates exhibited similar morphology and structural characteristics to the hollow ferritin cage and showed significant cytotoxicity than the naked drugs when tested on physiologically relevant 3D spheroid models. Precisely, our first designed carrier nanoconjugate, i.e., F-VPA, offered more than a 3-fold increased intratumoral drug concentration than free VPA and significantly suppressed tumor growth after a single-dose treatment. However, our second modeled carrier nanoconjugate, viz. F-VPA-Dox, revealed an extended median survival period and lesser toxicity when administered at a much more effective dose (∼3-5 μM), in 3D tumor spheroid models of various cancer cell lines. All in all, importantly, ferritin nanoconjugates exhibited an enhanced tumor inhibition rate with a single-dose treatment, which further confirms the benefits of the active targeting property of these nanocarriers. Moreover, these nanocarriers also offer to deliver a significant dose of the therapeutic drug into tumor cells, alongside tremendous biocompatibility and safety profiles in numerous tumor 3D spheroid models.

ATP-responsive copper(II)-doped ZIF-nanoparticles for synergistic cancer therapy: combining cuproptosis and chemo/chemodynamic therapy

Cancer, a pressing global health challenge, is characterized by its rapid onset and high mortality rates. Conventional treatment methods prove insufficient in achieving the desired therapeutic outcomes, underscoring the critical need to identify an effective and safe approach for cancer treatment. In this study, a copper-doped nanoparticle known as Cu2+-DOX@ZIF-90 is designed by incorporating copper(II) (Cu(II)) and encapsulating doxorubicin (DOX) within ZIF-90. Leveraging the elevated ATP levels in cancer cells relative to normal cells, Cu2+-DOX@ZIF-90 undergoes intracellular degradation, leading to the release of DOX and Cu(II). DOX, a traditional chemotherapy drug for clinical use, induces apoptosis in cancer cells. Cu(II) interacts with glutathione (GSH) to generate Cu(I), catalyzing H2O2 to produce ˙OH, thereby prompting apoptosis in cancer cells. Concurrently, the reduction of GSH enhances the therapeutic effect of chemodynamic therapy (CDT). Furthermore, Cu(II) triggers the aggregation of lipoylated mitochondrial proteins, leading to the formation of DLAT oligomers and ultimately promoting cuproptosis in cancer cells. In vivo experimental findings demonstrate that Cu2+-DOX@ZIF-90 does not cause damage to normal tissues and organs in tumor-bearing mice, with a notable tumor inhibition rate of 86.18%. This synergistic approach, combining chemotherapy, CDT, and cuproptosis, holds significant promise for the effective and safe treatment of cancer.

Mechanisms of myocardial toxicity of antitumor drugs and potential therapeutic strategies: A review of the literature

With the successive development of chemotherapy drugs, good results have been achieved in clinical application. However, myocardial toxicity is the biggest challenge. Anthracyclines, immune checkpoint inhibitors, and platinum drugs are widely used. Targeted drug delivery, nanomaterials and dynamic imaging evaluation are all emerging research directions. This article reviews the recent literature on the use of targeted nanodrug delivery and imaging techniques to evaluate the myocardial toxicity of antineoplastic drugs, and discusses the potential mechanisms.

A Versatile Virus-Mimetic Engineering Approach for Concurrent Protein Nanocage Surface-Functionalization and Cargo Encapsulation

Naturally occurring protein nanocages like ferritin are self-assembled from multiple subunits. Because of their unique cage-like structure and biocompatibility, there is a growing interest in their biomedical use. A multipurpose and straightforward engineering approach does not exist for using nanocages to make drug-delivery systems by encapsulating hydrophilic or hydrophobic drugs and developing vaccines by surface functionalization with a protein like an antigen. Here, a versatile engineering approach is described by mimicking the HIV-1 Gap polyprotein precursor. Various PREcursors of nanoCages (PREC) are designed and created by linking two ferritin subunits via a flexible linker peptide containing a protease cleavage site. These precursors can have additional proteins at their N-terminus, and their protease cleavage generates ferritin-like nanocages named protease-induced nanocages (PINCs). It is demonstrated that PINC formation allows concurrent surface decoration with a protein and hydrophilic or hydrophobic drug encapsulation up to fourfold more than the amount achieved using other methods. The PINCs/Drug complex is stable and efficiently kills cancer cells. This work provides insight into the precursors' design rules and the mechanism of PINCs formation. The engineering approach and mechanistic insight described here will facilitate nanocages' applications in drug delivery or as a platform for making multifunctional therapeutics like mosaic vaccines.

Protein nanoparticles as drug delivery systems for cancer theranostics

Protein-based nanoparticles have garnered significant attention in theranostic applications due to their superior biocompatibility, exceptional biodegradability and ease of functionality. Compared to other nanocarriers, protein-based nanoparticles offer additional advantages, including biofunctionality and precise molecular recognition abilities, which make them highly effective in navigating complex biological environments. Moreover, proteins can serve as powerful tools with self-assembling structures and reagents that enhance cell penetration. And their derivation from abundant renewable sources and ability to degrade into harmless amino acids further enhance their suitability for biomedical applications. However, protein-based nanoparticles have so far not realized their full potential. In this review, we summarize recent advances in the use of protein nanoparticles in tumor diagnosis and treatment and outline typical methods for preparing protein nanoparticles. The review of protein nanoparticles may provide useful new insights into the development of biomaterial fabrication.

Assembly Requirements for the Construction of Large-Scale Binary Protein Structures

The precise assembly of multiple biomacromolecules into well-defined structures and materials is of great importance for various biomedical and nanobiotechnological applications. In this study, we investigate the assembly requirements for two-component materials using charged protein nanocages as building blocks. To achieve this, we designed several variants of ferritin nanocages to determine the surface characteristics necessary for the formation of large-scale binary three-dimensional (3D) assemblies. These nanocage variants were employed in protein crystallization experiments and macromolecular crystallography analyses, complemented by computational methods. Through the screening of nanocage variant combinations at various ionic strengths, we identified three essential features for successful assembly: (1) the presence of a favored crystal contact region, (2) the presence of a charged patch not involved in crystal contacts, and (3) sufficient distinctiveness between the nanocages. Surprisingly, the absence of noncrystal contact mediating patches had a detrimental effect on the assemblies, highlighting their unexpected importance. Intriguingly, we observed the formation of not only binary structures but also both negatively and positively charged unitary structures under previously exclusively binary conditions. Overall, our findings will inform future design strategies by providing some design rules, showcasing the utility of supercharging symmetric building blocks in facilitating the assembly of biomacromolecules into large-scale binary 3D assemblies.

Heat sensitive E-helix cut ferritin nanocages for facile and high-efficiency loading of doxorubicin

Ferritin possesses a stable and uniform cage structure, along with tumor-targeting properties and excellent biocompatibility, making it a promising drug delivery vehicle. However, the current ferritin drug loading strategy involves complex steps and harsh reaction conditions, resulting in low yield and recovery of drug loading, which limits the clinical application prospects of ferritin nanomedicine. In this study, we utilized the high-efficiency heat-sensitivity of the multiple channel switch structures of the E-helix-cut ferritin mutant (Ecut-HFn) and Cu2+ assistance to achieve high-efficiency loading of chemotherapeutic drugs in a one-step process at low temperatures. This method features mild reaction conditions (45 °C), high loading efficiency (about 110 doxorubicin (Dox) per Ecut-HFn), and improved protein and Dox recovery rates (with protein recovery rate around 94 % and Dox recovery rate reaching up to 45 %). The prepared ferritin-Dox particles (Ecut-HFn-Cu-Dox) exhibit a uniform size distribution, good stability, and retain the natural tumor targeting ability of ferritin. Overall, this temperature-controlled drug loading strategy utilizing heat-sensitivity ferritin mutants is energy-saving, environmentally friendly, efficient, and easy to operate, offering a new perspective for scaling up the industrial production of ferritin drug carriers.

Electrospun Hyaluronan Nanofiber Membrane Immobilizing Aromatic Doxorubicin as Therapeutic and Regenerative Biomaterial

Lesioned tissue requires synchronous control of disease and regeneration progression after surgery. It is necessary to develop therapeutic and regenerative scaffolds. Here, hyaluronic acid (HA) was esterified with benzyl groups to prepare hyaluronic acid derivative (HA-Bn) nanofibers via electrospinning. Electrospun membranes with average fiber diameters of 407.64 ± 124.8 nm (H400), 642.3 ± 228.76 nm (H600), and 841.09 ± 236.86 nm (H800) were obtained by adjusting the spinning parameters. These fibrous membranes had good biocompatibility, among which the H400 group could promote the proliferation and spread of L929 cells. Using the postoperative treatment of malignant skin melanoma as an example, the anticancer drug doxorubicin (DOX) was encapsulated in nanofibers via hybrid electrospinning. The UV spectroscopy of DOX-loaded nanofibers (HA-DOX) revealed that DOX was successfully encapsulated, and there was a π-π interaction between aromatic DOX and HA-Bn. The drug release profile confirmed the sustained release of about 90%, achieved within 7 days. In vitro cell experiments proved that the HA-DOX nanofiber had a considerable inhibitory effect on B16F10 cells. Therefore, the HA-Bn electrospun membrane could facilitate the potential regeneration of injured skin tissues and be incorporated with drugs to achieve therapeutic effects, offering a powerful approach to developing therapeutic and regenerative biomaterial.