Regulation of NCOA4-mediated iron recycling ameliorates paraquat-induced lung injury by inhibiting ferroptosis.

Paraquat (PQ) is an irreplaceable insecticide in many countries for the advantage of fast-acting and broad-spectrum. However, PQ was classified as the most prevailing poisoning substance for suicide with no specific antidote. Therefore, it is imperative to develop more effective therapeutic agents for the treatment of PQ poisoning. In the present study, both the RNA-Seq and the application of various cell death inhibitors reflected that ferroptosis exerts a crucial regulatory role in PQ poisoning. Moreover, we found PQ strengthens lipid peroxidation as evidenced by different experimental approaches. Of note, pretreatment of iron chelation agent DFO could ameliorate the ferroptotic cell death and alleviate the ferroptosis-related events. Mechanistically, PQ treatment intensively impaired mitochondrial homeostasis, enhanced phosphorylation of AMPK, accelerated the autophagy flux and triggered the activation of Nuclear receptor coactivator 4-ferritin heavy chain (NCOA4-FTH) axis. Importantly, the activation of autophagy was observed prior to the degradation of ferritin, and inhibition of autophagy could inhibit the accumulation of iron caused by the ferritinophagy process. Genetic and pharmacological inhibition of ferritinophagy could alleviate the lethal oxidative events, and rescue the ferroptotic cell death. Excitingly, in the mouse models of PQ poisoning, both the administration of DFO and adeno-associated virus-mediated FTH overexpression significantly reduced PQ-induced ferroptosis and improved the pathological characteristics of pulmonary fibrosis. In summary, the current work provides an in-depth study on the mechanism of PQ intoxication, describes a framework for the further understanding of ferroptosis in PQ-associated biological processes, and demonstrates modulation of iron metabolism may act as a promising therapeutic agent for the management of PQ toxicity.

Iron accumulation induced by hepcidin1 knockout accelerates the progression of aging osteoporosis.

OBJECTIVE: Iron accumulation is associated with osteoporosis. This study aims to explore the effect of chronic iron accumulation induced by hepcidin1 deficiency on aging osteoporosis. METHODS: Iron accumulation in hepcidin1 knockout aging mice was assessed by atomic absorption spectroscopy and Perl's staining. Bone microarchitecture was observed using Micro-CT. Hepcidin, ferritin, oxidative stress, and markers of bone turnover in serum were detected by enzyme-linked immunosorbent assay. Bone formation and resorption markers were measured by real-time quantitative PCR. Cell aging was induced by D-galactose treatment. CCK-8, flow cytometry, EdU assays, and Alizarin red staining were performed to reveal the role of hepcidin1 knockout in cell model. Iron Colorimetric Assay Kit and western blot were applied to detect iron and ferritin levels in cells, respectively. RESULTS: In hepcidin1-knockout mice, the ferritin and iron contents in liver and tibia were significantly increased. Iron accumulation induced by hepcidin1 knockout caused a phenotype of low bone mass and deteriorated bone microarchitecture. Osteogenic marker was decreased and osteoclast marker was increased in mice, accompanied by increased oxidative stress level. The mRNA expression levels of osteoclast differentiation markers (RANKL, Mmp9, OPG, Trap, and CTSK) were up-regulated, while bone formation markers (OCN, ALP, Runx2, SP7, and Col-1) were down-regulated in model group, compared to wild type mice. In vitro, hepcidin1 knockdown inhibited proliferation and osteogenic differentiation, while promoted apoptosis, with increased levels of iron and ferritin. CONCLUSION: Iron accumulation induced by hepcidin1 deficiency aggravates the progression of aging osteoporosis via inhibiting osteogenesis and promoting osteoclast genesis.

Facile and green fabrication of tumor- and mitochondria-targeted AIEgen-protein nanoparticles for imaging-guided photodynamic cancer therapy.

In recent years, aggregation-induced emission (AIE)-active materials have been emerging as a promising means for bioimaging and phototherapy. However, the majority of AIE luminogens (AIEgens) need to be encapsulated into versatile nanocomposites to improve their biocompatibility and tumor targeting. Herein, we prepared a tumor- and mitochondria-targeted protein nanocage by the fusion of human H-chain ferritin (HFtn) with a tumor homing and penetrating peptide LinTT1 using genetic engineering technology. The LinTT1-HFtn could serve as a nanocarrier to encapsulate AIEgens via a simple pH-driven disassembly/reassembly process, thereby fabricating the dual-targeting AIEgen-protein nanoparticles (NPs). The as designed NPs exhibited an improved hepatoblastoma-homing property and tumor penetrating ability, which is favorable for tumor-targeted fluorescence imaging. The NPs also presented a mitochondria-targeting ability, and efficiently generated reactive oxygen species (ROS) upon visible light irradiation, making them valuable for inducing efficient mitochondrial dysfunction and intrinsic apoptosis in cancer cells. In vivo experiments demonstrated that the NPs could provide the accurate tumor imaging and dramatic tumor growth inhibition with minimal side effects. Taken together, this study presents a facile and green approach for fabrication of tumor- and mitochondria-targeted AIEgen-protein NPs, which can serve as a promising strategy for imaging-guided photodynamic cancer therapy. STATEMENT OF SIGNIFICANCE: AIE luminogens (AIEgens) show strong fluorescence and enhanced ROS generation in the aggregate state, which would facilitate the image-guided photodynamic therapy [12-14]. However, the major obstacles that hinder biological applications are their lack of hydrophilicity and selective targeting [15]. To address this issue, this study presents a facile and green approach for the fabrication of tumor­ and mitochondria­targeted AIEgen-protein nanoparticles via a simple disassembly/reassembly of the LinTT1 peptide-functionalized ferritin nanocage without any harmful chemicals or chemical modification. The targeting peptide-functionalized nanocage not only restricts the intramolecular motion of AIEgens leading to enhanced fluorescence and ROS production, but also confers good targeting to AIEgens.

Screening of superior anti-osteoporotic flavonoids from Epimedii Folium with dual effects of reversing iron overload and promoting osteogenesis.

Iron overload is a risk factor for postmenopausal osteoporosis (PMOP) and lowering iron levels to regulate the labile plasma iron is the preferred therapy. Icariin (ICA), baohuoside I (BHS) and icaritin (ICT) are three flavonoids obtained from Epimedii Folium that are efficient in facilitating osteogenesis. In this study, an active flavonoid with dual effects of reversing iron overload and promoting osteogenesis was screened based on pharmacokinetics, iron complexation properties and the potential to downregulate iron overload, reversing PMOP. As a result, the in vivo absorption of three compounds was ICA > ICT > BHS, while the exposure in muscle and bone was BHS > ICT > ICA. In vitro complexation showed that only ICT complexed with Fe (III) at a 1:1 ratio on 3-OH and the ICT-Fe (III) complex (m/z 424.3750) was identified by UPLC-Q-TOF-MS. In vivo dynamic detection also showed that the concentration of ICT-Fe (III) complexes varied with the concentration of ICT in plasma. The behavioral blunting and bone loss in zebrafish induced by Fe (III) were significantly reversed by ICT in a dose-dependent manner. Pharmacokinetic-pharmacodynamic analysis showed that ICT was negatively correlated with serum ferritin and positively correlated with osteogenic markers including alkaline phosphatase, osteocalcin and osteoprotegerin. Bone loss in ovariectomized rats was significantly altered after ICT intervention, with reduced serum ferritin levels and improved osteogenic marker levels. These results demonstrated that ICT had favorable musculoskeletal penetration and iron complexation capability to shrink labile plasma iron, showing superior performance in anti-PMOP through the dual effects of reversing iron overload and promoting osteogenesis.

Quercetin Promotes TFEB Nuclear Translocation and Activates Lysosomal Degradation of Ferritin to Induce Ferroptosis in Breast Cancer Cells.

Objective. To investigate the antiproliferative efficacy of quercetin on breast cell lines and its mechanism of ferroptosis regulation. Cells (MCF-7 and MDA-231) were treated with quercetin at 0.1, 1, and 10 µM, respectively. The cell counting kit-8 (CCK-8) assay was applied to assess cell viability, and the intracellular iron level, malondialdehyde (MDA), and carbonylated protein were measured. After treating the cells with quercetin, western blot was applied to determine the level of transcription factor EB (TFEB) and lysosomal-associated membrane protein 1 (LAMP-1) in cells. Meanwhile, western blot was performed to assess the nuclear translocation of TFEB protein in cells. TFEB siRNA and autophagy lysosomal inhibitor, chloroquine, were used to block ferroptosis induced by quercetin. Quercetin induced breast cancer cell death and upregulated the level of iron, MDA, and carbonyl protein in a concentration-dependent manner. Meanwhile, TFEB was highly expressed in the nucleus and lowly expressed in the cytoplasm. The high expression of TFEB promoted the expression of lysosome-related gene LAMP-1, which in turn promoted the degradation of ferritin and the release of ferric ions. The above pharmacodynamic effects of quercetin can be blocked by TFEB siRNA or chloroquine. Quercetin promotes TFEB expression and nuclear transcription, induces the onset of iron death, and thus exerts a pharmacological effect on killing breast cancer cells.

An ancient function of PGR5 in iron delivery?

In all phototrophic organisms, the photosynthetic apparatus must be protected from light-induced damage. One important mechanism that mitigates photodamage in plants is antimycin A (AA)-sensitive cyclic electron flow (CEF), the evolution of which remains largely obscure. Here we show that proton gradient regulation 5 (PGR5), a key protein involved in AA-sensitive CEF, displays intriguing commonalities - including sequence and structural features - with a group of ferritin-like proteins. We therefore propose that PGR5 may originally have been involved in prokaryotic iron mobilization and delivery, which facilitated a primordial type of CEF as a side effect. The abandonment of the bacterioferritin system during the transformation of cyanobacterial endosymbionts into chloroplasts might have allowed PGR5 to functionally specialize in CEF.

Bacterioferritin: a key iron storage modulator that affects strain growth and butenyl-spinosyn biosynthesis in Saccharopolyspora pogona.

BACKGROUND: Butenyl-spinosyn, produced by Saccharopolyspora pogona, is a promising biopesticide due to excellent insecticidal activity and broad pesticidal spectrum. Bacterioferritin (Bfr, encoded by bfr) regulates the storage and utilization of iron, which is essential for the growth and metabolism of microorganisms. However, the effect of Bfr on the growth and butenyl-spinosyn biosynthesis in S. pogona has not been explored. RESULTS: Here, we found that the storage of intracellular iron influenced butenyl-spinosyn biosynthesis and the stress resistance of S. pogona, which was regulated by Bfr. The overexpression of bfr increased the production of butenyl-spinosyn by 3.14-fold and enhanced the tolerance of S. pogona to iron toxicity and oxidative damage, while the knockout of bfr had the opposite effects. Based on the quantitative proteomics analysis and experimental verification, the inner mechanism of these phenomena was explored. Overexpression of bfr enhanced the iron storage capacity of the strain, which activated polyketide synthase genes and enhanced the supply of acyl-CoA precursors to improve butenyl-spinosyn biosynthesis. In addition, it induced the oxidative stress response to improve the stress resistance of S. pogona. CONCLUSION: Our work reveals the role of Bfr in increasing the yield of butenyl-spinosyn and enhancing the stress resistance of S. pogona, and provides insights into its enhancement on secondary metabolism, which provides a reference for optimizing the production of secondary metabolites in actinomycetes.

Genetically Modified Ferritin Nanoparticles with Bone-Targeting Peptides for Bone Imaging.

Bone homeostasis plays a major role in supporting and protecting various organs as well as a body structure by maintaining the balance of activities of the osteoblasts and osteoclasts. Unbalanced differentiation and functions of these cells result in various skeletal diseases, such as osteoporosis, osteopetrosis, and Paget's disease. Although various synthetic nanomaterials have been developed for bone imaging and therapy through the chemical conjugation, they are associated with serious drawbacks, including heterogeneity and random orientation, in turn resulting in low efficiency. Here, we report the synthesis of bone-targeting ferritin nanoparticles for bone imaging. Ferritin, which is a globular protein composed of 24 subunits, was employed as a carrier molecule. Bone-targeting peptides that have been reported to specifically bind to osteoblast and hydroxyapatite were genetically fused to the N-terminus of the heavy subunit of human ferritin in such a way that the peptides faced outwards. Ferritin nanoparticles with fused bone-targeting peptides were also conjugated with fluorescent dyes to assess their binding ability using osteoblast imaging and a hydroxyapatite binding assay; the results showed their specific binding with osteoblasts and hydroxyapatite. Using in vivo analysis, a specific fluorescent signal from the lower limb was observed, demonstrating a highly selective affinity of the modified nanoparticles for the bone tissue. These promising results indicate a specific binding ability of the nanoscale targeting system to the bone tissue, which might potentially be used for bone disease therapy in future clinical applications.

Randomized Placebo-Controlled Trial of Ferric Carboxymaltose in Heart Failure With Iron Deficiency: Rationale and Design.

BACKGROUND: Iron deficiency (ID) has a prevalence of ≈40% to 50% among patients in heart failure (HF) with reduced ejection fraction and is associated with worse prognosis. Several trials demonstrated that intravenous ferric carboxymaltose leads to early and sustained improvement in patient-reported outcomes and functional capacity in patients with HF with reduced ejection fraction with ID, yet morbidity and mortality data are limited. METHODS: The objective of the HEART-FID trial (Ferric Carboxymaltose in Heart Failure With Iron Deficiency) is to assess efficacy and safety of ferric carboxymaltose compared with placebo as treatment for symptomatic HF with reduced ejection fraction with ID. HEART-FID is a multicenter, randomized, double-blind, placebo-controlled trial enrolling ≈3014 patients at ≈300 international centers. Eligible patients are aged ≥18 years in stable chronic HF with New York Heart Association functional class II to IV symptoms, ejection fraction ≤40%, ID (ferritin <100 ng/mL or ferritin 100-300 ng/mL with a transferrin saturation <20%), and documented HF hospitalization or elevated N-terminal pro-brain natriuretic peptide. Consented patients are assigned to ferric carboxymaltose or placebo at baseline, with repeated visits/assessments every 6 months for additional study drug based on hemoglobin and iron indices for the trial duration. The primary end point is a hierarchical composite of death and HF hospitalization at 12 months and change from baseline to 6 months in the 6-minute walk test distance. CONCLUSIONS: The HEART-FID trial will inform clinical practice by clarifying the role of long-term treatment with intravenous ferric carboxymaltose, added to usual care, in ambulatory patients with symptomatic HF with reduced ejection fraction with ID. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03037931.

Arsenoplatin-Ferritin Nanocage: Structure and Cytotoxicity.

Arsenoplatin-1 (AP-1), the prototype of a novel class of metallodrugs containing a PtAs(OH)2 core, was encapsulated within the apoferritin (AFt) nanocage. UV-Vis absorption spectroscopy and inductively coupled plasma-atomic emission spectroscopy measurements confirmed metallodrug encapsulation and allowed us to determine the average amount of AP-1 trapped inside the cage. The X-ray structure of AP-1-encapsulated AFt was solved at 1.50 Å. Diffraction data revealed that an AP-1 fragment coordinates the side chain of a His residue. The biological activity of AP-1-loaded AFt was comparatively tested on a few representative cancer and non-cancer cell lines. Even though the presence of the cage reduces the overall cytotoxicity of AP-1, it improves its selectivity towards cancer cells.

Integrative proteomics and metabolomics profiling of the protective effects of Phascolosoma esculent ferritin on BMSCs in Cd(II) injury.

Ferritin is the major intracellular iron storage protein and is essential for iron homeostasis and detoxification. Cadmium affects cellular homeostasis and induces cell toxicity via sophisticated mechanisms. Here, we aimed to explore the mechanisms of cytoprotective effect of Phascolosoma esculenta ferritin (PeFer) on Cd(II)-induced bone marrow mesenchymal stem cell (BMSC) injury. Herein, the effects of different treated groups on apoptosis and cell cycle were assessed using flow cytometric analysis. We further investigated the alterations of the three groups using integrative 2-DE-based proteomics and 1H NMR-based metabolomics profiles. The results indicate that PeFer reduces BMSC apoptosis induced by Cd(II) and delays G0/G1 cell cycle progression. A total of 19 proteins and 70 metabolites were significantly different among BMSC samples of the three groups. Notably, multiomics analysis revealed that Cd(II) might perturb the ER stress-mediated apoptosis pathway and disrupt biological processes related to the TCA cycle, amino acid metabolism, purine and pyrimidine metabolism, thereby suppressing the cell growth rate and initiating apoptosis; however, the addition of PeFer might protect BMSCs against cell apoptosis to improve cell survival by enhancing energy metabolism. This study provides a better understanding of the underlying molecular mechanisms of the protective effect of PeFer in BMSCs against Cd(II) injury.

Broad Neutralization Responses Against Oncogenic Human Papillomaviruses Induced by a Minor Capsid L2 Polytope Genetically Incorporated Into Bacterial Ferritin Nanoparticles.

Cervical cancer remains a global health burden despite the introduction of highly effective vaccines for the prophylaxis of causative human papillomavirus infection (HPV). Current efforts to eradicate cervical cancer focus on the development of broadly protective, cost-effective approaches. HPV minor capsid protein L2 is being recognized as a promising alternative to the major capsid protein L1 because of its ability to induce responses against a wider range of different HPV types. However, a major limitation of L2 as a source of cross-neutralizing epitopes is its lower immunogenicity compared to L1 when assembled into VLPs. Various approaches have been proposed to overcome this limitation, we developed and tested ferritin-based bio-nanoparticles displaying tandemly repeated L2 epitopes from eight different HPV types grafted onto the surface of Pyrococcus furiosus thioredoxin (Pf Trx). Genetic fusion of the Pf Trx-L2(8x) module to P. furiosus ferritin (Pf Fe) did not interfere with ferritin self-assembly into an octahedral structure composed by 24 protomers. In guinea pigs and mice, the ferritin super-scaffolded, L2 antigen induced a broadly neutralizing antibody response covering 14 oncogenic and two non-oncogenic HPV types. Immune-responsiveness lasted for at least one year and the resulting antibodies also conferred protection in a cervico-vaginal mouse model of HPV infection. Given the broad organism distribution of thioredoxin and ferritin, we also verified the lack of cross-reactivity of the antibodies elicited against the scaffolds with human thioredoxin or ferritin. Altogether, the results of this study point to P. furiosus ferritin nanoparticles as a robust platform for the construction of peptide-epitope-based HPV vaccines.

Recombinant ferritin nanoparticles can induce dendritic cell maturation through TLR4/NF-κB pathway.

OBJECTIVE: Immune response initiation and regulation require activation of dendritic cells (DCs). However, the mechanism by which ferritin, a carrier for immunogen, induces DCs maturation remains unclear. RESULTS: Recombinant ferritin nanoparticle (RFNp), were prepared through the baculovirus expression vector system, formed spherical and hollow cage-liked proteins with a diameter of approximately 12.17 ± 0.87 nm. They induced bone marrow-derived DC (BMDC) maturation via surface molecules up-regulation of (MHC II, CD80, CD86 and CD40), increased pro-inflammatory cytokines production (IL-6, IL-12, TNF-α, and IFN-γ), and decreased antigen capturing capacity. They positively regulated IκBα and NF-κB (p65) phosphorylation, and facilitate NF-κB (p65) translocation into mature BMDCs nuclei. Following pre-treatment of RFNp-treated BMDCs with TLR4 and NF-κB (p65) inhibitors, respectively, surface molecule expression, pro-inflammatory cytokines production, and IκBα and NF-κB (p65) activities were suppressed. RFNp-treated BMDCs can also facilitate T-cell proliferation and differentiation into Th1 and Th2. CONCLUSION: RFNps induced DCs maturation lends the potential application of RFNps as carrier platforms in DC-based vaccine.

Label-free quantitative proteomics of the MCF-7 cellular response to a ferritin-metallodrug complex.

Auoxo3 is a gold(iii) compound endowed with cytotoxic activity towards a variety of malignant cells. Encapsulation of Auoxo3 within horse spleen ferritin (Ft) improves the selectivity of the gold compound towards cancer cells over normal cells. In the current work, the changes in protein expression are presented in response to MCF-7 stimulation with Auoxo3-encapsulated Ft versus the free Au(iii) compound by a label-free proteomics approach. A 159-protein dataset showed significant changes between the stimulations with Auoxo3 and Auoxo3-encapsulated Ft, suggesting that this cellular perturbation caused the alteration of different cellular processes. In detail, roughly 30% of proteins were downregulated mainly in the spliceosome complex (U2AF1, SF3B2, PRPF4, SNSRP200, EFTUD2, PRPF6, and PRPF8) in agreement with the cytostatic effect observed during cellular growth. Another 30% of proteins were upregulated primarily in glutathione biosynthesis, suggesting an alteration of the redox potential, as validated by Western blot analyses. To the best of our knowledge, this work represents the first large scale proteomics study on the effects of a gold-based drug encapsulated within the Ft nanocage on cancer cells.

Fenozyme Protects the Integrity of the Blood-Brain Barrier against Experimental Cerebral Malaria.

Cerebral malaria is a lethal complication of malaria infection characterized by central nervous system dysfunction and is often not effectively treated by antimalarial combination therapies. It has been shown that the sequestration of the parasite-infected red blood cells that interact with cerebral vessel endothelial cells and the damage of the blood-brain barrier (BBB) play critical roles in the pathogenesis. In this study, we developed a ferritin nanozyme (Fenozyme) composed of recombinant human ferritin (HFn) protein shells that specifically target BBB endothelial cells (BBB ECs) and the inner Fe3O4 nanozyme core that exhibits reactive oxygen species-scavenging catalase-like activity. In the experimental cerebral malaria (ECM) mouse model, administration of the Fenozyme, but not HFn, markedly ameliorated the damage of BBB induced by the parasite and improved the survival rate of infected mice significantly. Further investigations found that Fenozyme, as well as HFn, was able to polarize the macrophages in the liver to the M1 phenotype and promote the elimination of malaria in the blood. Thus, the catalase-like activity of the Fenozyme is required for its therapeutic effect in the mouse model. Moreover, the Fenozyme significantly alleviated the brain inflammation and memory impairment in ECM mice that had been treated with artemether, indicating that combining Fenozyme with an antimalarial drug is a novel strategy for the treatment of cerebral malaria.

Nanoparticle ferritin-bound erastin and rapamycin: a nanodrug combining autophagy and ferroptosis for anticancer therapy.

Ferroptosis and autophagy are the two forms of the regulation of cell death that play important roles in cancer therapy. However, little is known about the combination of the therapeutic effects of ferroptosis and autophagy in cancer therapy. Here, in this study, we constructed a novel carrier-free nanodrug called nanoparticle ferritin-bound erastin and rapamycin (NFER). The NFER nanodrug was prepared by the emulsification technique; it exhibited an average size of 78.8 nm and zeta potential of -25.9 ± 3.3 mV. Controllable drug encapsulation efficiency and loading ratios in NFER could be obtained. This nanodrug showed high stability in both water and PBS for several days. The release studies demonstrated that rapamycin and erastin could reach equilibrium after 24 h and 36 h, respectively; the maximum values of the released percentages of both reached beyond 30%. An in vitro study revealed that NFER showed robust ferroptosis-inducing capability by the downregulation of glutathione peroxidase-4 (GPX4) and lipid peroxidation accumulation. The autophagy process induced by rapamycin in NFER also played an important role in strengthening ferroptosis. The selective cancer cell killing ability of NFER was verified in cancer cells and normal cells. The ferroptosis-induced cytotoxicity was confirmed through several ferroptosis and autophagy inhibitors. Furthermore, the NFER nanodrug showed an improved control of tumor recurrence in the 4T1 tumor resection model. In summary, these results demonstrated that NFER exhibited excellent properties as a nanodrug, and the cell death induced by NFER was through an autophagy-associated ferroptosis pathway. This study based on protein nanodrug-induced autophagy-associated ferroptosis would provide a new insight into cancer therapy.

Intracellular iron availability modulates the requirement for Leishmania Iron Regulator 1 (LIR1) during macrophage infections.

The Leishmania plasma membrane transporter Leishmania Iron Regulator 1 (LIR1) facilitates iron export and is required for parasite virulence. By modulating macrophage iron content, we investigated the host site where LIR1 regulates Leishmania amazonensis infectivity. In bone marrow-derived macrophages, LIR1 null mutants demonstrated a paradoxical increase in virulence during infections in heme-depleted media, while wild-type growth was inhibited under the same conditions. Loading the endocytic pathway of macrophages with cationized ferritin prior to infection reversed the effect of heme depletion on both strains. Thus, LIR1 contributes to Leishmania virulence by protecting the parasites from toxicity resulting from iron accumulation inside parasitophorous vacuoles.

Enhancing the Effect of Pharmacological Ascorbate in Cancer Therapy via Acid-Triggered Ferritin Nanoparticles.

The application of ascorbate (vitamin C) for cancer therapy was first proposed in the 1970s and has shown promising results in recent clinical trials. Pharmacological doses of ascorbate selectively induce cell death in different types of cancer cells through the generation of H2 O2. However, some cancer cells are resistant to ascorbate. So increasing the sensitivity of resistant cancer cells to ascorbate has attracted considerable attention. Till now, a few attempts in nanomaterials have been made to improve the effect of ascorbate. In this study, a simple ferritin caged copper nanoparticle (Fn-Cu) significantly improves the susceptibility of ascorbate-resistant cancer cells to pharmacological ascorbate via selective inhibition of catalase activity in cancer cells, while having negligible cytotoxicity to normal cells. Remarkably, combination of Fn-Cu with a lower dose of ascorbate significantly inhibits ascorbate-resistant tumor growth and metastasis in vivo. These data demonstrate Fn-Cu has the therapeutic potential by enhancing the effect of ascorbate in cancer therapy.

Photosensitizer-Encapsulated Ferritins Mediate Photodynamic Therapy against Cancer-Associated Fibroblasts and Improve Tumor Accumulation of Nanoparticles.

Nanoparticles have been widely tested as drug delivery carriers or imaging agents, largely because of their ability to selectively accumulate in tumors through the enhanced permeability and retention (EPR) effect. However, studies show that many tumors afford a less efficient EPR effect and that many nanoparticles are trapped in the perivascular region after extravasation and barely migrate into tumor centers. This is to a large degree attributed to the dense tumor extracellular matrix (ECM), which functions as a physical barrier to prevent efficient nanoparticle extravasation and diffusion. In this study, we report a photodynamic therapy (PDT) approach to enhance tumor uptake of nanoparticles. Briefly, we encapsulate ZnF16Pc, a photosensitizer, into ferritin nanocages, and then conjugate to the surface of the ferritin a single chain viable fragment (scFv) sequence specific to fibroblast activation protein (FAP). FAP is a plasma surface protein widely upregulated in cancer-associated fibroblasts (CAFs), which is a major source of the ECM fiber components. We found that the scFv-conjugated and ZnF16Pc-loaded ferritin nanoparticles (scFv-Z@FRT) can mediate efficient and selective PDT, leading to eradication of CAFs in tumors. When tested in bilateral 4T1 tumor models, we found that the tumor accumulation of serum albumin (BSA), 10 nm quantum dots (QDs), and 50 nm QDs was increased by 2-, 3.5-, and 18-fold after scFv-Z@FRT mediated PDT. Our studies suggest a novel and safe method to enhance the delivery of nanoparticles to tumors.

Natural Diterpenoid Isoferritin A (IsoA) Inhibits Glioma Cell Growth and Metastasis via Regulating of TGFß-Induced EMT Signal Pathway.

BACKGROUND Malignant glioma is intractable primary brain carcinoma that has a poor survival rate. Natural diterpenoid isoferritin A (IsoA) presents antitumor effects by regulating signal pathways in tumor cells. In the present study we investigated the inhibitory effects of IsoA on glioma cells. MATERIAL AND METHODS The potential molecular mechanism of IsoA-mediated glioma cell growth and metastasis were investigated using Western blot, gene knockdown, immunofluorescence, and immunohistochemistry. RESULTS Results showed that IsoA significantly inhibits growth and metastasis of glioma cells in multiple preclinical settings. In vitro assay showed that IsoA (4 mg/ml) treatment significantly induced apoptosis of glioma cells. Mechanism analysis demonstrated that IsoA (4 mg/ml) treatment decreased TGFß and regulated EMT markers expression in glioma cells. Reduced expression of TGFß in glioma cells was closely correlated with inhibitory effects of IsoA on growth and metastasis of glioma cells. TGFß overexpression promoted glioma cell growth and invasion. Results also showed that IsoA treatment significantly decreased Fibronectin and Vimentin and increased E-cadherin, while TGFß overexpression abolished the regulation mediated by IsoA in glioma cells. In vivo assay showed that IsoA treatment inhibited tumor growth in a glioma-bearing mouse model. CONCLUSIONS Results indicate that IsoA could be regarded as a potential anti-cancer agent by regulating TGFß-induced EMT signal pathway.