Apoferritin and Dps as drug delivery vehicles: Some selected examples in oncology

BACKGROUND

The ideal nanoparticle should be able to encapsulate either pharmaceutical agents or imaging probes so that it could treat or image clinical tumours by targeting the cancer site efficiently. Further, it would be an added advantage if it demonstrates: small size, built in targeting, biocompatibility and biodegradability. Ferritin, which is an endogenous self-assembling protein, stores iron and plays a role in iron homeostasis. When iron atoms are removed apoferritin (AFt) is formed which consists of a hollow shell where it can be used to load guest molecules. Due to its unique architecture, AFt has been investigated as a versatile carrier for tumour theranostic applications. DNA-binding protein from starved cells (Dps), which also belongs to the ferritin family, is a protein found only in prokaryotes. It is used to store iron and protect chromosomes from oxidative damage; because of its architecture, Dps could also be used as a delivery vehicle.

CONCLUSIONS

Both these nano particles are promising in the field of oncology, especially due to their stability, solubility and biocompatibility features. Further their exterior surface can be modified for better tumour-targeting ability. More studies, are warranted to determine the immunogenicity, biodistribution, and clearance from the body.

GENERAL PERSPECTIVE

This review discusses a few selected examples of the remarkable in vitro and in vivo studies that have been carried out in the recent past with the use of AFt and Dps in targeting and delivery of various pharmaceutical agents, natural products and imaging probes in the field of oncology.

High Iron and Iron Household Protein Contents in Perineuronal Net-Ensheathed Neurons Ensure Energy Metabolism with Safe Iron Handling

A subpopulation of neurons is less vulnerable against iron-induced oxidative stress and neurodegeneration. A key feature of these neurons is a special extracellular matrix composition that forms a perineuronal net (PN). The PN has a high affinity to iron, which suggests an adapted iron sequestration and metabolism of the ensheathed neurons. Highly active, fast-firing neurons-which are often ensheathed by a PN-have a particular high metabolic demand, and therefore may have a higher need in iron. We hypothesize that PN-ensheathed neurons have a higher intracellular iron concentration and increased levels of iron proteins. Thus, analyses of cellular and regional iron and the iron proteins transferrin (Tf), Tf receptor 1 (TfR), ferritin H/L (FtH/FtL), metal transport protein 1 (MTP1 aka ferroportin), and divalent metal transporter 1 (DMT1) were performed on Wistar rats in the parietal cortex (PC), subiculum (SUB), red nucleus (RN), and substantia nigra (SNpr/SNpc). Neurons with a PN (PN⁺) have higher iron concentrations than neurons without a PN: PC 0.69 mM vs. 0.51 mM, SUB 0.84 mM vs. 0.69 mM, SN 0.71 mM vs. 0.63 mM (SNpr)/0.45 mM (SNpc). Intracellular Tf, TfR and MTP1 contents of PN⁺ neurons were consistently increased. The iron concentration of the PN itself is not increased. We also determined the percentage of PN⁺ neurons: PC 4%, SUB 5%, SNpr 45%, RN 86%. We conclude that PN⁺ neurons constitute a subpopulation of resilient pacemaker neurons characterized by a bustling iron metabolism and outstanding iron handling capabilities. These properties could contribute to the low vulnerability of PN⁺ neurons against iron-induced oxidative stress and degeneration.

Ferritin H can counteract inflammatory response in hybrid fish and its parental species after Aeromonas hydrophila infection

Ferritin H can participate in the regulation of fish immunity. Tissue-specific analysis revealed that the highest expressions of Ferritin H in parental species were observed in spleen, while peaked level of Ferritin H mRNA in hybrid fish was observed in liver. In addition, A. hydrophila challenge could sharply enhance their Ferritin H mRNA expression in liver, kidney and spleen. To further investigate their roles in immune regulation, their Ferritin H fusion proteins were produced in vitro. Ferritin H fusion proteins could exhibit a direct binding activity to A. hydrophila and endotoxin in a dose-dependent manner, restrict dissemination of A. hydrophila to tissues and abrogate inflammatory cascades. Moreover, treatment with Ferritin H fusion proteins could reduce A. hydrophila-induced lipid peroxidation. These results indicated that Ferritin H in hybrid fish elicited a similar immune regulation of A. hydrophila-induced inflammatory signals in comparison with those of its parents.

H-ferritin expression in astrocytes is necessary for proper oligodendrocyte development and myelination

How iron is delivered to the CNS for myelination is poorly understood. Astrocytes are the most abundant glial cells in the brain and are the only cells in close contact with blood vessels. Therefore, they are strategically located to obtain nutrients, such as iron, from circulating blood. To determine the importance of astrocyte iron uptake and storage in myelination and remyelination, we conditionally knocked-out the expression of the divalent metal transporter 1 (DMT1), the transferrin receptor 1 (Tfr1), and the ferritin heavy subunit (Fth) in Glast-1-positive astrocytes. DMT1 or Tfr1 ablation in astrocytes throughout early brain development did not significantly affects oligodendrocyte maturation or iron homeostasis. However, blocking Fth production in astrocytes during the first postnatal week drastically delayed oligodendrocyte development and myelin synthesis. Fth knockout animals presented an important decrease in the number of myelinating oligodendrocytes and a substantial reduction in the percentage of myelinated axons. This postnatal hypomyelination was accompanied by a decline in oligodendrocyte iron uptake and with an increase in brain oxidative stress. We also tested the relevance of astrocytic Fth expression in the cuprizone model of myelin damage and repair. Fth deletion in Glast1-positive astrocytes significantly reduced myelin production and the density of mature myelinating oligodendrocytes throughout the complete remyelination process. These results indicate that Fth iron storage in astrocytes is vital for early oligodendrocyte development as well as for the remyelination of the CNS.

Heme Oxygenase-1 (HMOX-1) and inhibitor of differentiation proteins (ID1, ID3) are key response mechanisms against iron-overload in pancreatic β-cells

Iron overload promotes the generation of reactive oxygen species (ROS). Pancreatic β-cells can counter oxidative stress through multiple anti-oxidant responses. Herein, RNA-sequencing was used to describe the expression profile of iron regulatory genes in human islets with or without diabetes. Functional experiments including siRNA silencing, qPCR, western blotting, cell viability, ELISA and RNA-sequencing were performed as means of identifying the genetic signature of the protective response following iron overload-induced stress in human islets and INS-1. FTH1 and FTL genes were highly expressed in human islets and INS-1 cells, while hepcidin (HAMP) was low. FXN, DMT1 and FTHL1 genes were differentially expressed in diabetic islets compared to control. Silencing of Hamp in INS-1 cells impaired insulin secretion and influenced the expression of β-cell key genes. RNA-sequencing analysis in iron overloaded INS-1 cells identified Id1 and Id3 as the top down-regulated genes, while Hmox1 was the top upregulated. Expression of ID1, ID3 and HMOX1 was validated at the protein level in INS-1 cells and human islets. Differentially expressed genes (DEGs) were enriched for TGF-β, regulating stem cells, ferroptosis, and HIF-1 signaling. Hmox1-silenced cells treated with FAC elevated the expression of Id1 and Id3 expression than untreated cells. Our findings suggest that HMOX1, ID1 and ID3 define the response mechanism against iron-overload-induced stress in β-cells.

JNK/Itch Axis Mediates the Lipopolysaccharide-Induced Ubiquitin-Proteasome-Dependent Degradation of Ferritin Light Chain in Murine Macrophage Cells

Ferritin, which is composed of a heavy chain and a light chain, plays a critical role in maintaining iron homeostasis by sequestering iron. The ferritin light chain (FTL) is responsible for the stability of the ferritin complex. We have previously shown that overexpression of FTL decreases the levels of the labile iron pool (LIP) and reactive oxygen species (ROS) in lipopolysaccharide (LPS)-treated murine macrophage cells. The protein level of FTL was downregulated by LPS within a short treatment period. However, the mechanism underlying the LPS-induced changes in the FTL levels is not known. In the present study, we report that LPS induces the ubiquitin-proteasome-dependent degradation of FTL and that the mechanism of LPS-induced FTL degradation involves the JNK/Itch axis. We found that LPS downregulates the protein and mRNA levels of FTL in a time-dependent manner. The proteasome inhibitor MG-132 significantly reverses the LPS-induced decrease in FTL. Furthermore, we observed that LPS treatment cannot cause ubiquitination of the lysine site (K105 and K144) mutant of FTL. Interestingly, LPS-mediated ubiquitin-dependent degradation of FTL is significantly inhibited by the JNK-specific inhibitor SP600125. Moreover, LPS could upregulate the protein level of E3 ubiquitin ligase Itch, a substrate of JNK kinases. Immunoprecipitation analyses revealed an increase in the association of FTL with Itch, a substrate of JNK kinases, in response to LPS stimulation. SP600125 decreased LPS-induced Itch upregulation. Taken together, these results suggest that LPS stimulation leads to the degradation of FTL through the ubiquitin-proteasome proteolytic pathway, and this FTL degradation is mediated by the JNK/Itch axis in murine macrophage cells.

Fusaricide is a Novel Iron Chelator that Induces Apoptosis through Activating Caspase-3

Nonsmall cell lung cancer (NSCLC) has been a fatal and refractory disease worldwide. Novel therapeutic developments based on fundamental investigations of anticancer mechanisms underlie substantial foundations to win the fight against cancer diseases. In this study, we isolated a natural product fusaricide (FCD) from an endophytic fungus of Lycium barbarum, identified as Epicoccum sp. For the first time, we discovered that FCD potently inhibited proliferation in a variety of human NSCLC cell lines, with relatively less toxicity to normal cells. Our study exhibited that FCD induced apoptosis, caused DNA damage and cell cycle arrest in G0/G1 phase, and activated caspase-3 as well as other apoptosis-related factors in human NSCLC NCI-H460 cells. FCD was proven to be an iron chelator that actively decreased levels of cellular labile iron pool in NCI-H460 cells in our study. FeCl₃ supplement reversed FCD-induced apoptosis. The upregulation of transferrin receptor 1 (TfR1) and downregulation of ferritin heavy chain (FTH) expression were observed after FCD treatment. In summary, our study highlighted the potential anticancer effects of FCD against human NSCLCs and demonstrated that the FCD-mediated apoptosis depended on binding to intracellular iron.

Autophagy-Dependent Apoptosis Induced by Apoferritin-Cu(II) Nanoparticles in Multidrug-Resistant Colon Cancer Cells

Chemotherapy continues to be the most commonly applied strategy for cancer. Despite the impressive clinical success obtained with several drugs, increasing numbers of (multi)drug-resistant tumors are reported. To overcome this shortcoming, novel drug candidates and delivery systems are urgently needed. Herein, a therapeutic copper polypyridine complex encapsulated in natural nanocarrier apoferritin is reported. The generated nanoparticles showed higher cytotoxicity toward various (drug-resistant) cancer cell lines than noncancerous cells. The study of the mechanism revealed that the compound triggers cell autophagy-dependent apoptosis. Promisingly, upon injection of the nanodrug conjugate into the bloodstream of a mouse model bearing a multidrug-resistant colon tumor, a strong tumor growth inhibition effect was observed. To date, this is the first study describing the encapsulation of a copper complex in apoferritin that acts by autophagy-dependent apoptosis.

Pathogenic mechanism and modeling of neuroferritinopathy

Neuroferritinopathy is a rare autosomal dominant inherited movement disorder caused by alteration of the L-ferritin gene that results in the production of a ferritin molecule that is unable to properly manage iron, leading to the presence of free redox-active iron in the cytosol. This form of iron has detrimental effects on cells, particularly severe for neuronal cells, which are highly sensitive to oxidative stress. Although very rare, the disorder is notable for two reasons. First, neuroferritinopathy displays features also found in a larger group of disorders named Neurodegeneration with Brain Iron Accumulation (NBIA), such as iron deposition in the basal ganglia and extrapyramidal symptoms; thus, the elucidation of its pathogenic mechanism may contribute to clarifying the incompletely understood aspects of NBIA. Second, neuroferritinopathy shows the characteristic signs of an accelerated process of aging; thus, it can be considered an interesting model to study the progress of aging. Here, we will review the clinical and neurological features of neuroferritinopathy and summarize biochemical studies and data from cellular and animal models to propose a pathogenic mechanism of the disorder.

Deletion of ferritin H in neurons counteracts the protective effect of melatonin against traumatic brain injury-induced ferroptosis

Accumulating evidence demonstrates that ferroptosis may be important in the pathophysiological process of traumatic brain injury (TBI). As a major hormone of the pineal gland, melatonin exerts many beneficial effects on TBI, but there is no information regarding the effects of melatonin on ferroptosis after TBI. As expected, TBI resulted in the time-course changes of ferroptosis-related molecules expression and iron accumulation in the ipsilateral cortex. Importantly, we found that treating with melatonin potently rescued TBI induced the changes mentioned above and improved functional deficits versus vehicle. Similar results were obtained with a ferroptosis inhibitor, liproxstatin-1. Moreover, the protective effect of melatonin is likely dependent on melatonin receptor 1B (MT2). Although ferritin plays a vital role in iron metabolism by storing excess cellular iron, its precise function in the brain, and whether it involves melatonin's neuroprotection remain unexplored. Considering ferritin H (Fth) is expressed predominantly in the neurons and global loss of Fth in mice induces early embryonic lethality, we then generated neuron-specific Fth conditional knockout (Fth-KO) mice, which are viable and fertile but have altered iron metabolism. In addition, Fth-KO mice were more susceptible to ferroptosis after TBI, and the neuroprotection by melatonin was largely abolished in Fth-KO mice. In vitro siFth experiments further confirmed the results mentioned above. Taken together, these data indicate that melatonin produces cerebroprotection, at least partly by inhibiting neuronal Fth-mediated ferroptosis following TBI, supporting the notion that melatonin is an excellent ferroptosis inhibitor and its anti-ferroptosis provides a potential therapeutic target for treating TBI.

Chimeric ferritin H in hybrid crucian carp exhibits a similar down-regulation in lipopolysaccharide-induced NF-κB inflammatory signal in comparison with Carassius cuvieri and Carassius auratus red var

Ferritin H can participate in the regulation of teleostean immunity. ORF sequences of RCC/WCC/WR-ferritin H were 609 bp, while WR-ferritin H gene possessed chimeric fragments or offspring-specific mutations. In order to elucidate regulation of immune-related signal transduction, three fibroblast-like cell lines derived from caudal fin of red crucian carp (RCC), white crucian carp (WCC) and their hybrid offspring (WR) were characterized and designated as RCCFCs, WCCFCs and WRFCs. A sharp increase of ferritin H mRNA was observed in RCCFCs, WCCFCs and WRFCs following lipopolysaccharide (LPS) challenge. Overexpression of RCC/WCC/WR-ferritin H can decrease MyD88-IRAK4 signal and antagonize NF-κB, TNFα promoter activity in RCCFCs, WCCFCs and WRFCs, respectively. These results indicated that ferritin H in hybrid offspring harbors highly-conserved domains with a close sequence similarity to those of its parents, playing a regulatory role in inflammatory signals.

Nourin-Dependent miR-137 and miR-106b: Novel Early Inflammatory Diagnostic Biomarkers for Unstable Angina Patients

BACKGROUND

Currently, no blood biomarkers exist that can diagnose unstable angina (UA) patients. Nourin is an early inflammatory mediator rapidly released within 5 min by reversible ischemic myocardium, and if ischemia persists, it is also released by necrosis. Nourin is elevated in acute coronary syndrome (ACS) patients but not in symptomatic noncardiac and healthy subjects. Recently, circulating microRNAs (miRNAs) have been established as markers of disease, including cardiac injury and inflammation.

OBJECTIVES

To profile and validate the potential diagnostic value of Nourin-dependent miR-137 (marker of cell damage) and miR-106b-5p (marker of inflammation) as early biomarkers in suspected UA patients and to investigate the association of their target and regulating genes.

METHODS

Using Nourin amino acid sequence, an integrated bioinformatics analysis was conducted. Analysis indicated that Nourin is a direct target for miR-137 and miR-106b-5p in myocardial ischemic injury. Two linked molecular networks of lncRNA/miRNAs/mRNAs were also retrieved, including CTB89H12.4/miR-137/FTHL-17 and CTB89H12.4/miR-106b-5p/ANAPC11. Gene expression profiling was assessed in serum samples collected at presentation to an emergency department (ED) from: (1) UA patients (n = 30) (confirmed by invasive coronary angiography with stenosis greater than 50% and troponin level below the clinical decision limit); (2) patients with acute ST elevation myocardial infarction (STEMI) (n = 16) (confirmed by persistent ST-segment changes and elevated troponin level); and 3) healthy subjects (n = 16).

RESULTS

Gene expression profiles showed that miR-137 and miR-106b-5p were significantly upregulated by 1382-fold and 192-fold in UA compared to healthy, and by 2.5-fold and 4.6-fold in STEMI compared to UA, respectively. Healthy subjects showed minimal expression profile. Receiver operator characteristics (ROC) analysis revealed that the two miRNAs were sensitive and specific biomarkers for assessment of UA and STEMI patients. Additionally, Spearman's correlation analysis revealed a significant association of miRNAs with the associated mRNA targets and the regulating lncRNA.

CONCLUSIONS

Nourin-dependent gene expression of miR-137 and miR-106b-5p are novel blood-based biomarkers that can diagnose UA and STEMI patients at presentation and stratify severity of myocardial ischemia, with higher expression in STEMI compared to UA. Early diagnosis of suspected UA patients using the novel Nourin biomarkers is key for initiating guideline-based therapy that improves patients' health outcomes.

Iron loading is a prominent feature of activated microglia in Alzheimer's disease patients

Brain iron accumulation has been found to accelerate disease progression in amyloid-β(Aβ) positive Alzheimer patients, though the mechanism is still unknown. Microglia have been identified as key players in the disease pathogenesis, and are highly reactive cells responding to aberrations such as increased iron levels. Therefore, using histological methods, multispectral immunofluorescence and an automated in-house developed microglia segmentation and analysis pipeline, we studied the occurrence of iron-accumulating microglia and the effect on its activation state in human Alzheimer brains. We identified a subset of microglia with increased expression of the iron storage protein ferritin light chain (FTL), together with increased Iba1 expression, decreased TMEM119 and P2RY12 expression. This activated microglia subset represented iron-accumulating microglia and appeared morphologically dystrophic. Multispectral immunofluorescence allowed for spatial analysis of FTL+Iba1+-microglia, which were found to be the predominant Aβ-plaque infiltrating microglia. Finally, an increase of FTL+Iba1+-microglia was seen in patients with high Aβ load and Tau load. These findings suggest iron to be taken up by microglia and to influence the functional phenotype of these cells, especially in conjunction with Aβ.

Selective Targeting of Cancer-Associated Fibroblasts by Engineered H-Ferritin Nanocages Loaded with Navitoclax

Cancer-associated fibroblasts (CAFs) are key actors in regulating cancer progression. They promote tumor growth, metastasis formation, and induce drug resistance. For these reasons, they are emerging as potential therapeutic targets. Here, with the aim of developing CAF-targeted drug delivery agents, we functionalized H-ferritin (HFn) nanocages with fibroblast activation protein (FAP) antibody fragments. Functionalized nanocages (HFn-FAP) have significantly higher binding with FAP+ CAFs than with FAP- cancer cells. We loaded HFn-FAP with navitoclax (Nav), an experimental Bcl-2 inhibitor pro-apoptotic drug, whose clinical development is limited by its strong hydrophobicity and toxicity. We showed that Nav is efficiently loaded into HFn (HNav), maintaining its mechanism of action. Incubating Nav-loaded functionalized nanocages (HNav-FAP) with FAP+ cells, we found significantly higher cytotoxicity as compared to non-functionalized HNav. This was correlated with a significantly higher drug release only in FAP+ cells, confirming the specific targeting ability of functionalized HFn. Finally, we showed that HFn-FAP is able to reach the tumor and to target CAFs in a mouse syngeneic model of triple negative breast cancer after intravenous administration. Our data show that HNav-FAP could be a promising tool to enhance specific drug delivery into CAFs, thus opening new therapeutic possibilities focused on tumor microenvironment.

Kinetic factors may reshape the dependence of crystal nucleation rate on temperature in protein bulk solution

Here we provide an analysis of primary results obtained from a study of apoferritin crystal nucleation in compositionally invariant bulk solution at constant supersaturation ratio of the protein. The temperature dependence of the stationary crystal nucleation rate in the protein bulk solution is obtained with the help of experimentally determined probability for detection of at least one crystal per solution volume until a given time. The stationary crystal nucleation rate demonstrates unusual behavior with temperature. We emphasize that this is caused by kinetic factors that are often disregarded in the frame of the classical nucleation theory but can certainly affect the nucleation kinetics.

Quantification of Iron Release from Native Ferritin and Magnetoferritin Induced by Vitamins B2 and C

Various pathological processes in humans are associated with biogenic iron accumulation and the mineralization of iron oxide nanoparticles, especially magnetite. Ferritin has been proposed as a precursor to pathological magnetite mineralization. This study quantifies spectroscopically the release of ferrous ions from native ferritin and magnetoferritin as a model system for pathological ferritin in the presence of potent natural reducing agents (vitamins C and B2) over time. Ferrous cations are required for the transformation of ferrihydrite (physiological) into a magnetite (pathological) mineral core and are considered toxic at elevated levels. The study shows a significant difference in the reduction and iron release from native ferritin compared to magnetoferritin for both vitamins. The amount of reduced iron formed from a magnetoferritin mineral core is two to five times higher than from native ferritin. Surprisingly, increasing the concentration of the reducing agent affects only iron release from native ferritin. Magnetoferritin cores with different loading factors seem to be insensitive to different concentrations of vitamins. An alternative hypothesis of human tissue magnetite mineralization and the process of iron-induced pathology is proposed. The results could contribute to evidence of the molecular mechanisms of various iron-related pathologies, including neurodegeneration.

Deletion of H-ferritin in macrophages alleviates obesity and diabetes induced by high-fat diet in mice

AIMS/HYPOTHESIS

Iron accumulation affects obesity and diabetes, both of which are ameliorated by iron reduction. Ferritin, an iron-storage protein, plays a crucial role in iron metabolism. H-ferritin exerts its cytoprotective action by reducing toxicity via its ferroxidase activity. We investigated the role of macrophage H-ferritin in obesity and diabetes.

METHODS

Conditional macrophage-specific H-ferritin (Fth, also known as Fth1) knockout (LysM-Cre Fth KO) mice were used and divided into four groups: wild-type (WT) and LysM-Cre Fth KO mice with normal diet (ND), and WT and LysM-Cre Fth KO mice with high-fat diet (HFD). These mice were analysed for characteristics of obesity and diabetes, tissue iron content, inflammation, oxidative stress, insulin sensitivity and metabolic measurements. RAW264.7 macrophage cells were used for in vitro experiments.

RESULTS

Iron concentration reduced, and mRNA expression of ferroportin increased, in macrophages from LysM-Cre Fth KO mice. HFD-induced obesity was lower in LysM-Cre Fth KO mice than in WT mice at 12 weeks (body weight: KO 34.6 ± 5.6 g vs WT 40.1 ± 5.2 g). mRNA expression of inflammatory cytokines and infiltrated macrophages and oxidative stress increased in the adipose tissue of HFD-fed WT mice, but was not elevated in HFD-fed LysM-Cre Fth KO mice. However, WT mice fed an HFD had elevated iron concentration in adipose tissue and spleen, which was not observed in LysM-Cre Fth KO mice fed an HFD (adipose tissue [μmol Fe/g protein]: KO 1496 ± 479 vs WT 2316 ± 866; spleen [μmol Fe/g protein]: KO 218 ± 54 vs WT 334 ± 83). Moreover, HFD administration impaired both glucose tolerance and insulin sensitivity in WT mice, which was ameliorated in LysM-Cre Fth KO mice. In addition, energy expenditure, mRNA expression of thermogenic genes, and body temperature were higher in KO mice with HFD than WT mice with HFD. In vitro experiments showed that iron content was reduced, and lipopolysaccharide-induced Tnf-α (also known as Tnf) mRNA upregulation was inhibited in a macrophage cell line transfected with Fth siRNA.

CONCLUSIONS/INTERPRETATION

Deletion of macrophage H-ferritin suppresses the inflammatory response by reducing intracellular iron levels, resulting in the prevention of HFD-induced obesity and diabetes. The findings from this study highlight macrophage iron levels as a potential therapeutic target for obesity and diabetes.

Role of Fermented Goat Milk on Liver Gene and Protein Profiles Related to Iron Metabolism during Anemia Recovery

Despite the crucial role of the liver as the central regulator of iron homeostasis, no studies have directly tested the modulation of liver gene and protein expression patterns during iron deficiency instauration and recovery with fermented milks. Fermented goat milk consumption improves the key proteins of intestinal iron metabolism during iron deficiency recovery, enhancing the digestive and metabolic utilization of iron. The aim of this study was to assess the influence of fermented goat or cow milk consumption on liver iron homeostasis during iron-deficiency anemia recovery with normal or iron-overload diets. Analysis included iron status biomarkers, gene and protein expression in hepatocytes. In general, fermented goat milk consumption either with normal or high iron content up-regulated liver DMT1, FPN1 and FTL1 gene expression and DMT1 and FPN1 protein expression. However, HAMP mRNA expression was lower in all groups of animals fed fermented goat milk. Additionally, hepcidin protein expression decreased in control and anemic animals fed fermented goat milk with normal iron content. In conclusion, fermented goat milk potentiates the up-regulation of key genes coding for proteins involved in iron metabolism, such as DMT1, and FPN1, FTL1 and down-regulation of HAMP, playing a key role in enhanced iron repletion during anemia recovery, inducing a physiological adaptation of the liver key genes and proteins coordinated with the fluctuation of the cellular iron levels, favoring whole-body iron homeostasis.

TfR1 binding with H-ferritin nanocarrier achieves prognostic diagnosis and enhances the therapeutic efficacy in clinical gastric cancer

H-ferritin (HFn) nanocarrier is emerging as a promising theranostic platform for tumor diagnosis and therapy, which can specifically target tumor cells via binding transferrin receptor 1 (TfR1). This led us to investigate the therapeutic function of TfR1 in GC. The clinical significance of TfR1 was assessed in 178 GC tissues by using a magneto-HFn nanoparticle-based immunohistochemistry method. The therapeutic effects of doxorubicin-loaded HFn nanocarriers (HFn-Dox) were evaluated on TfR1-positive GC patient-derived xenograft (GC-PDX) models. The biological function of TfR1 was investigated through in vitro and in vivo assays. TfR1 was upregulated (73.03%) in GC tissues, and reversely correlated with patient outcome. TfR1-negative sorted cells exhibited tumor-initiating features, which enhanced tumor formation and migration/invasion, whereas TfR1-positive sorted cells showed significant proliferation ability. Knockout of TfR1 in GC cells also enhanced cell invasion. TfR1-deficient cells displayed immune escape by upregulating PD-L1, CXCL9, and CXCL10, when disposed with IFN-γ. Western blot results demonstrated that TfR1-knockout GC cells upregulated Akt and STAT3 signaling. Moreover, in TfR1-positive GC-PDX models, the HFn-Dox group significantly inhibited tumor growth, and increased mouse survival, compared with that of free-Dox group. TfR1 could be a potential prognostic and therapeutic biomarker for GC: (i) TfR1 reversely correlated with patient outcome, and its negative cells possessed tumor-aggressive features; (ii) TfR1-positive cells can be killed by HFn drug nanocarrier. Given the heterogeneity of GC, HFn drug nanocarrier combined with other therapies toward TfR1-negative cells (such as small molecules or immunotherapy) will be a new option for GC treatment.

Transferrin and H-ferritin involvement in brain iron acquisition during postnatal development: impact of sex and genotype

Iron delivery to the developing brain is essential for energy and metabolic support needed for processes such as myelination and neuronal development. Iron deficiency, especially in the developing brain, can result in a number of long-term neurological deficits that persist into adulthood. There is considerable debate that excess access to iron during development may result in iron overload in the brain and subsequently predispose individuals to age-related neurodegenerative diseases. There is a significant gap in knowledge regarding how the brain acquires iron during development and how biological variables such as development, genetics, and sex impact brain iron status. In this study, we used a mouse model expressing a mutant form of the iron homeostatic regulator protein HFE, (Hfe H63D), the most common gene variant in Caucasians, to determine impact of the mutation on brain iron uptake. Iron uptake was assessed using 59 Fe bound to either transferrin or H-ferritin as the iron carrier proteins. We demonstrate that at postnatal day 22, mutant mice brains take up greater amounts of iron compared with wildtype. Moreover, we introduce H-ferritin as a key protein in brain iron transport during development and identify a sex and genotype effect demonstrating female mutant mice take up more iron by transferrin, whereas male mutant mice take up more iron from H-ferritin at PND22. Furthermore, we begin to elucidate the mechanism for uptake using immunohistochemistry to profile the regional distribution and temporal expression of transferrin receptor and T-cell immunoglobulin and mucin domain 2, the latter is the receptor for H-ferritin. These data demonstrate that sex and genotype have significant effects on iron uptake and that regional receptor expression may play a large role in the uptake patterns during development. Open Science: This manuscript was awarded with the Open Materials Badge For more information see: https://cos.io/our-services/open-science-badges/ Cover Image for this issue: doi: 10.1111/jnc.14731.

Protein Encapsulation of Experimental Anticancer Agents 5F 203 and Phortress: Towards Precision Drug Delivery

INTRODUCTION

Advancement of novel anticancer drugs into clinical use is frequently halted by their lack of solubility, reduced stability under physiological conditions, and non-specific uptake by normal tissues, causing systemic toxicity. Their progress to use in the clinic could be accelerated by the development of new formulations employing suitable and complementary drug delivery vehicles.

METHODS

A robust method for apoferritin (AFt)-encapsulation of antitumour benzothiazoles has been developed for enhanced activity against and drug delivery to benzothiazole-sensitive cancers.

RESULTS

More than 70 molecules of benzothiazole 5F 203 were encapsulated per AFt cage. Post-encapsulation, the size and integrity of the protein cages were retained as evidenced by dynamic light scattering. ToF-SIMS depth profiling using an argon cluster beam confirmed 5F 203 exclusively within the AFt cavity. Improved encapsulation of benzothiazole lysyl-amide prodrugs was achieved (~130 molecules of Phortress per AFt cage). Transferrin receptor 1, TfR1, was detected in lysates prepared from most cancer cell lines studied, contributing to enhanced anticancer potency of the AFt-encapsulated benzothiazoles (5F 203, Phortress, GW 610, GW 608-Lys). Nanomolar activity was demonstrated by AFt-formulations in breast, ovarian, renal and gastric carcinoma cell lines, whereas GI50 >50 µM was observed in non-tumourigenic MRC-5 fibroblasts. Intracellular 5F 203, a potent aryl hydrocarbon receptor (AhR) ligand, and inducible expression of cytochrome P450 (CYP) 1A1 were detected following exposure of sensitive cells to AFt-5F 203, confirming that the activity of benzothiazoles was not compromised following encapsulation.

CONCLUSION

Our results show enhanced potency and selectivity of AFt-encapsulated 5F 203 against carcinomas derived from breast, ovarian, renal, colorectal as well as gastric cancer models, and offer realistic prospects for potential refinement of tumour-targeting and treatment, and merit further in vivo investigations.

A photosynthesis-inspired supramolecular system: caging photosensitizer and photocatalyst in apoferritin

Inspired by the bioinorganic structure of natural [FeFe]-hydrogenase ([FeFe]-H₂ase) that possesses iron sulfur clusters to catalyze proton reduction to hydrogen (H₂), we design a supramolecular photosystem by sequentially integrating hydrophobic ruthenium complex (as a photosensitizer) and diiron dithiolate complex (as a photocatalyst) into the inner surface or cavity of apoferritin via noncovalent interactions. This platform allows photosensitizer and catalyst to localize in a close proximity and short-distance electron transfer process to occur within a confined space. The resulted uniform core-shell nanocomposites were stable and well dispersed in water, and showed enhanced H₂ generation activity in acidic solution as compared to the homogenous system without apoferritin participation.

Ferritin heavy chain protects the developing wing from reactive oxygen species and ferroptosis

The interplay between signalling pathways and metabolism is crucial for tissue growth. Yet, it remains poorly understood. Here, we studied the consequences of modulating iron metabolism on the growth of Drosophila imaginal discs. We find that reducing the levels of the ferritin heavy chain in the larval wing discs leads to drastic growth defects, whereas light chain depletion causes only minor defects. Mutant cell clones for the heavy chain lack the ability to compete against Minute mutant cells. Reactive oxygen species (ROS) accumulate in wing discs with reduced heavy chain levels, causing severe mitochondrial defects and ferroptosis. Preventing ROS accumulation alleviates some of the growth defects. We propose that the increased expression of ferritin in hippo mutant cells may protect against ROS accumulation.

Despite being vital, the role of metals in biology is often overlooked. Specifically, how iron storage contributes to development remains unclear. Here, we dissected the function of the cellular iron storage complex, Ferritin, during development of a model organ, the fly wing. We took a genetic approach to uncover the role of both the heavy and light chains of Ferritin. Targeting the heavy chain consistently produced drastic growth defects in larval discs and adult wings. Moreover, lower levels of the heavy chain led to formation of reactive oxygen species (ROS) and preventing ROS accumulation alleviated the accompanying growth defects. We also observed hallmarks of ferroptosis, an iron dependent non-apoptotic cell death, upon knockdown of the heavy chain. By contrast, reducing the levels of the light chain was tolerable. This is surprising because the individual components of Ferritin were thought to function exclusively as part of the complex. Yet, the heavy chain alone encompasses the ferroxidase center, which is essential for iron loading. All together, we propose that the Ferritin heavy chain functions as an antioxidant and protects the developing organs from ferroptosis.

Identification and functional analysis of an iron-binding protein, ferritin heavy chain subunit, from the swallowtail butterfly, Papilio xuthus

Ferritin, which is ubiquitous among all living organisms, plays a crucial role in maintaining iron homeostasis, immune response, and detoxification. In the present research, we identified an iron-binding protein, ferritin heavy chain subunit, from Papilio xuthus and named PxFerHCH. The complete complementary DNA of PxFerHCH was 1,252 bp encoding a sequence of 211 amino acids, which includes an iron-responsive element. Phylogenetic analysis showed that PxFerHCH is clustered with Manduca sexta and Galleria mellonella ferritin heavy chain subunits. Expression levels of PxFerHCH in various tissues were analyzed by reverse transcription quantitative polymerase chain reaction, and the results exhibited that PxFerHCH was expressed in all tissues with the highest expression in the fat body. The relative expression level of PxFerHCH in response to bacterial (Escherichia coli and Staphylococcus aureus) challenges sharply increased by about 12 hr postinfection (hpi) and then decreased at 24 hpi. In addition, the iron-binding capacity and antioxidation activity of recombinant PxFerHCH protein were also investigated. These results reveal that PxFerHCH might play an important role in defense against bacterial infection.

Morphine-Induced Modulation of Endolysosomal Iron Mediates Upregulation of Ferritin Heavy Chain in Cortical Neurons

HIV-associated neurocognitive disorders (HAND) remain prevalent and are aggravated by µ-opioid use. We have previously shown that morphine and other µ-opioids may contribute to HAND by inhibiting the homeostatic and neuroprotective chemokine receptor CXCR4 in cortical neurons, and this novel mechanism depends on upregulation of the protein ferritin heavy chain (FHC). Here, we examined the cellular events and potential mechanisms involved in morphine-mediated FHC upregulation using rat cortical neurons of either sex in vitro and in vivo. Morphine dose dependently increased FHC protein levels in primary neurons through µ-opioid receptor (µOR) and Gαi-protein signaling. Cytoplasmic FHC levels were significantly elevated, but nuclear FHC levels and FHC gene expression were unchanged. Morphine-treated rats also displayed increased FHC levels in layer 2/3 neurons of the prefrontal cortex. Importantly, both in vitro and in vivo FHC upregulation was accompanied by loss of mature dendritic spines, which was also dependent on µOR and Gαi-protein signaling. Moreover, morphine upregulated ferritin light chain (FLC), a component of the ferritin iron storage complex, suggesting that morphine altered neuronal iron metabolism. Indeed, prior to FHC upregulation, morphine increased cytoplasmic labile iron levels as a function of decreased endolysosomal iron. In line with this, chelation of endolysosomal iron (but not extracellular iron) blocked morphine-induced FHC upregulation and dendritic spine reduction, whereas iron overloading mimicked the effect of morphine on FHC and dendritic spines. Overall, these data demonstrate that iron mediates morphine-induced FHC upregulation and consequent dendritic spine deficits and implicate endolysosomal iron efflux to the cytoplasm in these effects.