Iron deprivation in cancer--potential therapeutic implications

Inhibition of IRP2-dependent reprogramming of iron metabolism suppresses tumor growth in colorectal cancer

BACKGROUND

Dysregulation of iron metabolism is implicated in malignant transformation, cancer progression, and therapeutic resistance. Here, we demonstrate that iron regulatory protein 2 (IRP2) preferentially regulates iron metabolism and promotes tumor growth in colorectal cancer (CRC).

METHODS

IRP2 knockdown and knockout cells were generated using RNA interference and clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 methodologies, respectively. Cell viability was evaluated using both CCK-8 assay and cell counting techniques. Furthermore, IRP2 inhibition was determined by surface plasmon resonance (SPR) and RNA immunoprecipitation (IP). The suppressive effects of IRP2 were also corroborated in both organoid and mouse xenograft models, providing a comprehensive validation of IRP2's role.

RESULTS

We have elucidated the role of IRP2 as a preferential regulator of iron metabolism, actively promoting tumorigenesis within CRC. Elevated levels of IRP2 expression in patient samples are correlated with diminished overall survival, thereby reinforcing its potential role as a prognostic biomarker. The functional suppression of IRP2 resulted in a pronounced delay in tumor growth. Building on this proof of concept, we have developed IRP2 inhibitors that significantly reduce IRP2 expression and hinder its interaction with iron-responsive elements in key iron-regulating proteins, such as ferritin heavy chain 1 (FTH1) and transferrin receptor (TFRC), culminating in iron depletion and a marked reduction in CRC cell proliferation. Furthermore, these inhibitors are shown to activate the AMPK-ULK1-Beclin1 signaling cascade, leading to cell death in CRC models.

CONCLUSIONS

Collectively, these findings highlight the therapeutic potential of targeting IRP2 to exploit the disruption of iron metabolism in CRC, presenting a strategic advancement in addressing a critical area of unmet clinical need.

Identification of TFRC as a biomarker for pulmonary arterial hypertension based on bioinformatics and experimental verification

BACKGROUND

Pulmonary arterial hypertension (PAH) is a life-threatening chronic cardiopulmonary disease. However, there is a paucity of studies that reflect the available biomarkers from separate gene expression profiles in PAH.

METHODS

The GSE131793 and GSE113439 datasets were combined for subsequent analyses, and batch effects were removed. Bioinformatic analysis was then performed to identify differentially expressed genes (DEGs). Weighted gene co-expression network analysis (WGCNA) and a protein-protein interaction (PPI) network analysis were then used to further filter the hub genes. Functional enrichment analysis of the intersection genes was performed using Gene Ontology (GO), Disease Ontology (DO), Kyoto encyclopedia of genes and genomes (KEGG) and gene set enrichment analysis (GSEA). The expression level and diagnostic value of hub gene expression in pulmonary arterial hypertension (PAH) patients were also analyzed in the validation datasets GSE53408 and GSE22356. In addition, target gene expression was validated in the lungs of a monocrotaline (MCT)-induced pulmonary hypertension (PH) rat model and in the serum of PAH patients.

RESULTS

A total of 914 differentially expressed genes (DEGs) were identified, with 722 upregulated and 192 downregulated genes. The key module relevant to PAH was selected using WGCNA. By combining the DEGs and the key module of WGCNA, 807 genes were selected. Furthermore, protein-protein interaction (PPI) network analysis identified HSP90AA1, CD8A, HIF1A, CXCL8, EPRS1, POLR2B, TFRC, and PTGS2 as hub genes. The GSE53408 and GSE22356 datasets were used to evaluate the expression of TFRC, which also showed robust diagnostic value. According to GSEA enrichment analysis, PAH-relevant biological functions and pathways were enriched in patients with high TFRC levels. Furthermore, TFRC expression was found to be upregulated in the lung tissues of our experimental PH rat model compared to those of the controls, and the same conclusion was reached in the serum of the PAH patients.

CONCLUSIONS

According to our bioinformatics analysis, the observed increase of TFRC in the lung tissue of human PAH patients, as indicated by transcriptomic data, is consistent with the alterations observed in PAH patients and rodent models. These data suggest that TFRC may serve as a potential biomarker for PAH.

Ferroptosis is an effective strategy for cancer therapy

Ferroptosis is a form of intracellular iron-dependent cell death that differs from necrosis, autophagy and apoptosis. Intracellular iron mediates Fenton reaction resulting in lipid peroxidation production, which in turn promotes cell death. Although cancer cell exhibit's ability to escape ferroptosis by multiple pathways such as SLC7A11, GPX4, induction of ferroptosis could inhibit cancer cell proliferation, migration and invasion. In tumor microenvironment, ferroptosis could affect immune cell (T cells, macrophages etc.) activity, which in turn regulates tumor immune escape. In addition, ferroptosis in cancer cells could activate immune cell activity by antigen processing and presentation. Therefore, ferroptosis could be an effective strategy for cancer therapy such as chemotherapy, radiotherapy, and immunotherapy. In this paper, we reviewed the role of ferroptosis on tumor progression and therapy, which may provide a strategy for cancer treatment.

Vitamin E stabilizes iron and mitochondrial metabolism in pulmonary fibrosis

Introduction: Pulmonary fibrosis (PF) is a fatal chronic lung disease that causes structural damage and decreased lung function and has a poor prognosis. Currently, there is no medicine that can truly cure PF. Vitamin E (VE) is a group of natural antioxidants with anticancer and antimutagenic properties. There have been a few reports about the attenuation of PF by VE in experimental animals, but the molecular mechanisms are not fully understood. Methods: Bleomycin-induced PF (BLM-PF) mouse model, and cultured mouse primary lung fibroblasts and MLE 12 cells were utilized. Pathological examination of lung sections, immunoblotting, immunofluorescent staining, and real-time PCR were conducted in this study. Results: We confirmed that VE significantly delayed the progression of BLM-PF and increased the survival rates of experimental mice with PF. VE suppressed the pathological activation and fibrotic differentiation of lung fibroblasts and epithelial-mesenchymal transition and alleviated the inflammatory response in BLM-induced fibrotic lungs and pulmonary epithelial cells in vitro. Importantly, VE reduced BLM-induced ferritin expression in fibrotic lungs, whereas VE did not exhibit iron chelation properties in fibroblasts or epithelial cells in vitro. Furthermore, VE protected against mitochondrial dysmorphology and normalized mitochondrial protein expression in BLM-PF lungs. Consistently, VE suppressed apoptosis in BLM-PF lungs and pulmonary epithelial cells in vitro. Discussion: Collectively, VE markedly inhibited BLM-induced PF through a complex mechanism, including improving iron metabolism and mitochondrial structure and function, mitigating inflammation, and decreasing the fibrotic functions of fibroblasts and epithelial cells. Therefore, VE presents a highly potential therapeutic against PF due to its multiple protective effects with few side effects.

Core-shell inorganic NP@MOF nanostructures for targeted drug delivery and multimodal imaging-guided combination tumor treatment

It is well known that metal-organic framework (MOF) nanostructures have unique characteristics such as high porosity, large surface areas and adjustable functionalities, so they are ideal candidates for developing drug delivery systems (DDSs) as well as theranostic platforms in cancer treatment. Despite the large number of MOF nanostructures that have been discovered, conventional MOF-derived nanosystems only have a single biofunctional MOF source with poor colloidal stability. Accordingly, developing core-shell MOF nanostructures with good colloidal stability is a useful method for generating efficient drug delivery, multimodal imaging and synergistic therapeutic systems. The preparation of core-shell MOF nanostructures has been done with a variety of materials, but inorganic nanoparticles (NPs) are highly effective for drug delivery and imaging-guided tumor treatment. Herein, we aimed to overview the synthesis of core-shell inorganic NP@MOF nanostructures followed by the application of core-shell MOFs derived from magnetic, quantum dots (QDs), gold (Au), and gadolinium (Gd) NPs in drug delivery and imaging-guided tumor treatment. Afterward, we surveyed different factors affecting prolonged drug delivery and cancer therapy, cellular uptake, biocompatibility, biodegradability, and enhanced permeation and retention (EPR) effect of core-shell MOFs. Last but not least, we discussed the challenges and the prospects of the field. We envision this article may hold great promise in providing valuable insights regarding the application of hybrid nanostructures as promising and potential candidates for multimodal imaging-guided combination cancer therapy.

A protein complex of LCN2, LOXL2 and MMP9 facilitates tumour metastasis in oesophageal cancer

During malignant tumour development, the extracellular matrix (ECM) is usually abnormally regulated. Dysregulated expression of lysyl oxidase-like 2 (LOXL2), matrix metalloproteinase 9 (MMP9) and lipocalin 2 (LCN2) are associated with ECM remodelling. In this study, protein-protein interaction assays indicated that LCN2 and LOXL2 interactions and LCN2 and MMP9 interactions occurred both intracellularly and extracellularly, but interactions between LOXL2 and MMP9 only occurred intracellularly. The LCN2/LOXL2/MMP9 ternary complex promoted migration and invasion of oesophageal squamous cell carcinoma (ESCC) cells, as well as tumour growth and malignant progression in vivo, while the iron chelator deferoxamine mesylate (DFOM) inhibited ESCC tumour growth. Co-overexpression of LCN2, LOXL2 and MMP9 enhanced the ability of tumour cells to degrade fibronectin and Matrigel, increased the formation and extension of filopodia, and promoted the rearrangement of microfilaments through upregulation of profilin 1. In addition, the LCN2/LOXL2/MMP9 ternary complex promoted the expression of testican-1 (SPOCK1), and abnormally activated the FAK/AKT/GSK3β signalling pathway. In summary, the LCN2/LOXL2/MMP9 ternary complex promoted the migration and invasion of cancer cells and malignant tumour progression through multiple mechanisms and could be a potential therapeutic target.

Reduced sulfatide content in deferoxamine-induced senescent HepG2 cells

Iron chelators, such as deferoxamine, exert an anticancer effect by altering the activity of biomolecules critical for regulation of the cell cycle, cell metabolism, and apoptotic processes. Thus, iron chelators are sometimes used in combination with radio- and/or chemotherapy in the treatment of cancer. The possibility that deferoxamine could induce a program of senescence similar to radio- and/or chemotherapy, fostering adaptation in the treatment of cancer cells, is not fully understood. Using established biochemical techniques, biomarkers linked to lipid composition, and coherent anti-Stokes Raman scattering microscopy, we demonstrated that hepatocellular carcinoma-derived HepG2 cells survive after deferoxamine treatment, acquiring phenotypic traits and representative hallmarks of senescent cells. The results support the view that deferoxamine acts in HepG2 cells to produce oxidative stress-induced senescence by triggering sequential mitochondrial and lysosomal dysfunction accompanied by autophagy blockade. We also focused on the lipidome of senescent cells after deferoxamine treatment. Using mass spectrometry, we found that the deferoxamine-induced senescent cells presented marked remodeling of the phosphoinositol, sulfatide, and cardiolipin profiles, which all play a central role in cell signaling cascades, intracellular membrane trafficking, and mitochondria functions. Detection of alterations in glycosphingolipid sulfate species suggested modifications in ceramide generation, and turnover is frequently described in cancer cell survival and resistance to chemotherapy. Blockade of ceramide generation may explain autophagic default, resistance to apoptosis, and the onset of senescence. DATA AVAILABILITY STATEMENT: All analyses relevant to the study were included in the article or uploaded as Supplementary Information.

Iron supplementation enhances RSL3-induced ferroptosis to treat naïve and prevent castration-resistant prostate cancer

Prostate cancer (PCa) is a leading cause of death in the male population commonly treated with androgen deprivation therapy that often relapses as androgen-independent and aggressive castration-resistant prostate cancer (CRPC). Ferroptosis is a recently described form of cell death that requires abundant cytosolic labile iron to promote membrane lipid peroxidation and which can be induced by agents that inhibit the glutathione peroxidase-4 activity such as RSL3. Exploiting in vitro and in vivo human and murine PCa models and the multistage transgenic TRAMP model of PCa we show that RSL3 induces ferroptosis in PCa cells and demonstrate for the first time that iron supplementation significantly increases the effect of RSL3 triggering lipid peroxidation, enhanced intracellular stress and leading to cancer cell death. Moreover, the combination with the second generation anti-androgen drug enzalutamide potentiates the effect of the RSL3 + iron combination leading to superior inhibition of PCa and preventing the onset of CRPC in the TRAMP mouse model. These data open new perspectives in the use of pro-ferroptotic approaches alone or in combination with enzalutamide for the treatment of PCa.

Therapy-resistant nature of cancer stem cells in view of iron metabolism

Due to increased resistance to standard chemo/radiotherapies and relapse, highly tumorigenic cancer stem cells (CSCs) have been proposed as a promising target for the development of effective cancer treatments. In order to develop innovative cancer therapies that target CSCs, much attention has focused on the iron metabolism of CSCs, which has been considered to contribute to self-renewal of CSCs. Here, we review recent advances in iron metabolism and conventional iron metabolism-targeted cancer therapies, as well as therapy resistance of CSCs and potential treatment options to overcome them, which provide important insights into therapeutic strategies against intractable cancers. Potential treatment options targeting iron homeostasis, including small-molecule inhibitors, nanotechnology platforms, ferroptosis, and 5-ALA-PDT, might be a focus of future research for the development of innovative cancer therapies that tackle CSCs.

Evaluation of trace elements in essential thrombocytosis and reactive thrombocytosis

BACKGROUND

Trace elements (TE) are vital for cellular mechanisms at biological, chemical and molecular levels. The effects of TE in diagnosis, progression and treatment of essential thrombocytosis (ET), which is one of the chronic myeloproliferative neoplasms is a rare clonal stem cell disease characterized by increased thrombocyte numbers with impaired function, have not been elucidated in detail yet. The aim of the present study was to investigate the effects of TE alterations in an ET model and the efficacy of TE in ET treatment protocol by means of a vast number of TE.

METHODS

Study groups were categorized as patients with ET diagnosis (ET group, n:30), patients with reactive thrombocytosis secondary to iron deficiency anemia (IDA-RT) (IDA-RT group, n:30) and healthy controls (HC group, n:30). Serum levels of copper (Cu), iron (Fe), cobalt (Co), chromium (Cr), aluminum (Al), silicon (Si), nickel (Ni), zinc (Zn), selenium (Se), manganese (Mn), boron (B) and magnesium (Mg) were analyzed utilizing inductively coupled plasma-optical emission spectrophotometer instrument (ICP-OES). Statistical analysis was evaluated using SPSS 23.0.

RESULTS

ET group had statistically higher serum levels of Co and Mg (p < 0.05), Ni and Mn (p < 0.001), and lower Si (p < 0.05) than IDA-RT group. ET group had statistically higher serum levels of Co and Mn (p < 0.05), and Ni (p < 0.001), and lower Al, Si and Se (p < 0.001) than HC group. Serum levels of Fe, Al and Se (p < 0.001), and Mg (p < 0.01), and Zn (p < 0.05) in IDA-RT group were significantly lower than HC group.

CONCLUSION

This novel study pointed out that alterations of many serum TE by means of both increment or decrement might have close relationship with mechanisms and complications of ET onset and follow-up. We consider that further research of TE would elucidate ethiopathogenesis and prognosis of ET. Thus, analysis of serum trace elements in essential thrombocytosis patients may be an important protocol by means of diagnosis, treatment and follow-up intervals.

Iron accumulation typifies renal cell carcinoma tumorigenesis but abates with pathological progression, sarcomatoid dedifferentiation, and metastasis

Iron is a potent catalyst of oxidative stress and cellular proliferation implicated in renal cell carcinoma (RCC) tumorigenesis, yet it also drives ferroptosis that suppresses cancer progression and represents a novel therapeutic target for advanced RCC. The von Hippel Lindau (VHL)/hypoxia-inducible factor-α (HIF-α) axis is a major regulator of cellular iron, and its inactivation underlying most clear cell (cc) RCC tumors introduces both iron dependency and ferroptosis susceptibility. Despite the central role for iron in VHL/HIF-α signaling and ferroptosis, RCC iron levels and their dynamics during RCC initiation/progression are poorly defined. Here, we conducted a large-scale investigation into the incidence and prognostic significance of total tissue iron in ccRCC and non-ccRCC patient primary tumor cancer cells, tumor microenvironment (TME), metastases and non-neoplastic kidneys. Prussian Blue staining was performed to detect non-heme iron accumulation in over 1600 needle-core sections across multiple tissue microarrays. We found that RCC had significantly higher iron staining scores compared with other solid cancers and, on average, >40 times higher than adjacent renal epithelium. RCC cell iron levels correlated positively with TME iron levels and inversely with RCC levels of the main iron uptake protein, transferrin receptor 1 (TfR1/TFRC/CD71). Intriguingly, RCC iron levels, including in the TME, decreased significantly with pathologic (size/stage/grade) progression, sarcomatoid dedifferentiation, and metastasis, particularly among patients with ccRCC, despite increasing TfR1 levels, consistent with an increasingly iron-deficient tumor state. Opposite to tumor iron changes, adjacent renal epithelial iron increased significantly with RCC/ccRCC progression, sarcomatoid dedifferentiation, and metastasis. Lower tumor iron and higher renal epithelial iron each predicted significantly shorter ccRCC patient metastasis-free survival. In conclusion, iron accumulation typifies RCC tumors but declines toward a relative iron-deficient tumor state during progression to metastasis, despite precisely opposite dynamics in adjacent renal epithelium. These findings raise questions regarding the historically presumed selective advantage for high iron during all phases of cancer evolution, suggesting instead distinct tissue-specific roles during RCC carcinogenesis and early tumorigenesis versus later progression. Future study is warranted to determine how the relative iron deficiency of advanced RCC contributes to ferroptosis resistance and/or introduces a heightened susceptibility to iron deprivation that might be therapeutically exploitable.

Puzzling Out Iron Complications in Cancer Drug Resistance

Iron metabolism are frequently disrupted in cancer. Patients with cancer are prone to anemia and receive transfusions frequently; the condition which results in iron overload, contributing to serious therapeutic complications. Iron is introduced as a carcinogen that may increase tumor growth. However, investigations regarding its impact on response to chemotherapy, particularly the induction of drug resistance are still limited. Here, iron contribution to cell signaling and various molecular mechanisms underlying iron-mediated drug resistance are described. A dual role of this vital element in cancer treatment is also addressed. On one hand, the need to administer iron chelators to surmount iron overload and improve the sensitivity of tumor cells to chemotherapy is discussed. On the other hand, the necessary application of iron as a therapeutic option by iron-oxide nanoparticles or ferroptosis inducers is explained. Authors hope that this paper can help unravel the clinical complications related to iron in cancer therapy.

A Review on the Recent Advancements on Therapeutic Effects of Ions in the Physiological Environments

This review focuses on the therapeutic effects of ions when released in physiological environments. Recent studies have shown that metallic ions like Ag+, Sr2+, Mg2+, Mn2+, Cu2+, Ca2+, P+5, etc., have shown promising results in drug delivery systems and regenerative medicine. These metallic ions can be loaded in nanoparticles, mesoporous bioactive glass nanoparticles (MBGNs), hydroxyapatite (HA), calcium phosphates, polymeric coatings, and salt solutions. The metallic ions can exhibit different functions in the physiological environment such as antibacterial, antiviral, anticancer, bioactive, biocompatible, and angiogenic effects. Furthermore, the metals/metalloid ions can be loaded into scaffolds to improve osteoblast proliferation, differentiation, bone development, fibroblast growth, and improved wound healing efficacy. Moreover, different ions possess different therapeutic limits. Therefore, further mechanisms need to be developed for the highly controlled and sustained release of these ions. This review paper summarizes the recent progress in the use of metallic/metalloid ions in regenerative medicine and encourages further study of ions as a solution to cure diseases.

Supplementation with High or Low Iron Reduces Colitis Severity in an AOM/DSS Mouse Model

The relationship between colitis-associated colorectal cancer (CAC) and the dysregulation of iron metabolism has been implicated. However, studies on the influence of dietary iron deficiency on the incidence of CAC are limited. This study investigated the effects of dietary iron deficiency and dietary non-heme iron on CAC development in an azoxymethane/dextran sodium sulfate (AOM/DSS) mouse model. The four-week-old mice were divided into the following groups: iron control (IC; 35 ppm iron/kg) + normal (NOR), IC + AOM/DSS, iron deficient (ID; <5 ppm iron/kg diet) + AOM/DSS, and iron overload (IOL; approximately 2000 ppm iron/kg) + AOM/DSS. The mice were fed the respective diets for 13 weeks, and the AOM/DSS model was established at week five. FTH1 expression increased in the mice’s colons in the IC + AOM/DSS group compared with that observed in the ID and IOL + AOM/DSS groups. The reduced number of colonic tumors in the ID + AOM/DSS and IOL + AOM/DSS groups was accompanied by the downregulated expression of cell proliferation regulators (PCNA, cyclin D1, and c-Myc). Iron overload inhibited the increase in the expression of NF-κB and its downstream inflammatory cytokines (IL-6, TNFα, iNOS, COX2, and IL-1β), likely due to the elevated expression of antioxidant genes (SOD1, TXN, GPX1, GPX4, CAT, HMOX1, and NQO1). ID + AOM/DSS may hinder tumor development in the AOM/DSS model by inhibiting the PI3K/AKT pathway by increasing the expression of Ndrg1. Our study suggests that ID and IOL diets suppress AOM/DSS-induced tumors and that long-term iron deficiency or overload may negate CAC progression.

Tumor Microenvironment-Responsive Nanodrug for Clear-Cell Renal Cell Carcinoma Therapy via Triggering Waterfall-Like Cascade Ferroptosis

The most common type of kidney tumor, clear-cell renal cell carcinoma (ccRCC) with relatively insidious development and easily metastatic characteristics is generally insensitive to cytotoxic chemotherapy. The abundant polyunsaturated fatty acids (PUFAs) content in advanced ccRCC allows it to be intrinsically vulnerable to ferroptosis-based therapeutic strategies. Nevertheless, the strategy to cause the "iron overload" by administration with iron-based nanomaterials has limited therapeutic efficacy. And the classic ferroptosis agonist (RSL3) with low specificity for tumors, short half-life in the blood, poor water solubility and deficient accumulation at the tumor site prevents its reliable application in vivo. In this study, iron-based metal-organic framework nanoparticles (MIL-101(Fe) NPs) delivered RSL3 to ccRCC tumors, and then released the iron ions and RSL3 accompanied by the degradation of MIL-101(Fe) NPs in the acidic tumor microenvironment. The MIL-101(Fe)@RSL3 as a pH-responsive nanodrug causes cellular iron overload and promotes the hydroxyl radical (^•OH) generation by Fenton reaction to attack PUFAs, leading to the aberrant accumulation of lipid peroxides (L-OOH). Additionally, RSL3 directly inhibits glutathione peroxidase 4 (GPX4) to detoxify L-OOH, and ferrous ions further catalyze the irreversible conversion of highly reactive lipid alkoxyl radicals (L-O^•) from L-OOH to triggering waterfall-like cascade ferroptosis. In contrast to the limited antitumor efficiency of free RSL3, MIL-101(Fe)@RSL3 with high encapsulation efficiency (88.7%) shows a significant ccRCC-specific antitumor effect and negligible side effects. Taken together, MIL-101(Fe)@RSL3 could aggravate ferroptosis and be expected to be a promising nanodrug for ccRCC systemic therapy due to the targeted delivery and responsive release of RSL3 and iron ions.

Stimulating TRPM7 suppresses cancer cell proliferation and metastasis by inhibiting autophagy

The transient receptor potential melastatin-subfamily member 7 (TRPM7) is a ubiquitous cation channel possessing kinase activity. TRPM7 mediates a variety of physiological responses by conducting flow of cations such as Ca²⁺, Mg²⁺, and Zn²⁺. Here, we show that the activation of TRPM7 channel stimulated by chemical agonists of TRPM7, Clozapine or Naltriben, inhibited autophagy via mediating Zn²⁺ release to the cytosol, presumably from the intracellular Zn²⁺-accumulating vesicles where TRPM7 localizes. Zn²⁺ release following the activation of TRPM7 disrupted the fusion between autophagosomes and lysosomes by disturbing the interaction between Sxt17 and VAMP8 which determines fusion status of autophagosomes and lysosomes. Ultimately, the disrupted fusion resulting from stimulation of TRPM7 channels arrested autophagy. Functionally, we demonstrate that the autophagy inhibition mediated by TRPM7 triggered cell death and suppressed metastasis of cancer cells in vitro, more importantly, restricted tumor growth and metastasis in vivo, by evoking apoptosis, cell cycle arrest, and reactive oxygen species (ROS) elevation. These findings represent a strategy for stimulating TRPM7 to combat cancer.

Liposomes: An Emerging Approach for the Treatment of Cancer

BACKGROUND

Conventional drug delivery agents for a life-threatening disease, i.e., cancer, lack specificity towards cancer cells, producing a greater degree of side effects in the normal cells with a poor therapeutic index. These toxic side effects often limit dose escalation of anti-cancer drugs, leading to incomplete tumor suppression/ cancer eradication, early disease relapse, and ultimately, the development of drug resistance. Accordingly, targeting the tumor vasculatures is essential for the treatment of cancer.

OBJECTIVE

To search and describe a safer drug delivery carrier for the treatment of cancer with reduced systemic toxicities.

METHOD

Data were collected from Medline, PubMed, Google Scholar, Science Direct using the following keywords: 'liposomes', 'nanocarriers', 'targeted drug delivery', 'ligands', 'liposome for anti-cancerous drugs', 'treatment for cancer' and 'receptor targeting.'

RESULTS

Liposomes have provided a safe platform for the targeted delivery of encapsulated anti-cancer drugs for the treatment of cancer, which results in the reduction of the cytotoxic side effects of anti-cancer drugs on normal cells.

CONCLUSION

Liposomal targeting is a better emerging approach as an advanced drug delivery carrier with targeting ligands for anti-cancer agents.

Osteoblast iron genes: real time PCR and microarray hybridization approach under hyperoxia

OBJECTIVES

Iron is essential for cell growth, differentiation, electron transfer, and oxygen transport. Hyperoxia may increase the turnover of bone matrix components with a net effect of accelerated bone growth. Although hyperoxia was claimed could increase osteoblast activity, but expression level in possible genes which play role in proliferation is still unclear. This research aims to prove the differences of expression level of transferrin receptor gene and iron regulated transporter and other genes of 7F2 under 24 h normoxia, 24 h hyperoxia, and 48 h hyperoxia and the effect of hyperoxia by using osteoblast cell culture 7F₂.

METHODS

Reverse transcriptase, real time Polymerase Chain Reaction (PCR), and microarray is used to qualitatively detect gene expression. The computer softwares such as National Center for Biotechnology Information (NCBI) data base, Software Affymetrix, DNA Strider program, Genomatix - DiAlign program, Oligo 5.0 program (Software primer design) from Wojciech & Piotr Rychlik, and Genetyx-Mac version 8.0 have been used to analyze the PCR result.

RESULTS

Under 24 h hyperoxia, there were 3,884 copies of transferrin receptor mRNA per 1,000,000 copies of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) mRNA. After 24 h hyperoxia, 8,325 copies of transferrin receptor mRNA per 1,000,000 GAPDH mRNA copies were found showing 2.1-fold up regulation. After 48 h hyperoxia, there was no significant increase at the level of expression of transferrin receptor mRNA, 8,079 mRNA copies per 1,000,000 copies of mRNA were found (2.0-fold up regulation compared with 24 h normoxia).

CONCLUSIONS

It can be concluded that hyperoxia might have an effect on upregulating the expression of some osteoblast genes which might have an impact on osteoblast activity.

In vitro studies of deferasirox derivatives as potential organelle-targeting traceable anti-cancer therapeutics

We report here strategic functionalization of the FDA approved chelator deferasirox (1) in an effort to produce organelle-targeting iron chelators with enhanced activity against A549 lung cancer cells. Derivative 8 was found to have improved antiproliferative activity relative to 1. Fluorescent cell imaging revealed that compound 8 preferentially localises within the lysosome.

MCOLN1/TRPML1 finely controls oncogenic autophagy in cancer by mediating zinc influx

Macroautophagy/autophagy is elevated to ensure the high demand for nutrients for the growth of cancer cells. Here we demonstrated that MCOLN1/TRPML1 is a pharmaceutical target of oncogenic autophagy in cancers such as pancreatic cancer, breast cancer, gastric cancer, malignant melanoma, and glioma. First, we showed that activating MCOLN1, by increasing expression of the channel or using the MCOLN1 agonists, ML-SA5 or MK6-83, arrests autophagic flux by perturbing fusion between autophagosomes and lysosomes. Second, we demonstrated that MCOLN1 regulates autophagy by mediating the release of zinc from the lysosome to the cytosol. Third, we uncovered that zinc influx through MCOLN1 blocks the interaction between STX17 (syntaxin 17) in the autophagosome and VAMP8 in the lysosome and thereby disrupting the fusion process that is determined by the two SNARE proteins. Furthermore, we demonstrated that zinc influx originating from the extracellular fluid arrests autophagy by the same mechanism as lysosomal zinc, confirming the fundamental function of zinc as a participant in membrane trafficking. Last, we revealed that activating MCOLN1 with the agonists, ML-SA5 or MK6-83, triggers cell death of a number of cancer cells by evoking autophagic arrest and subsequent apoptotic response and cell cycle arrest, with little or no effect observed on normal cells. Consistent with the in vitro results, administration of ML-SA5 in Patu 8988 t xenograft mice profoundly suppresses tumor growth and improves survival. These results establish that a lysosomal cation channel, MCOLN1, finely controls oncogenic autophagy in cancer by mediating zinc influx into the cytosol.

A fully human anti-BMP6 antibody reduces the need for erythropoietin in rodent models of the anemia of chronic disease

Recombinant erythropoietin (EPO) and iron substitution are a standard of care for treatment of anemias associated with chronic inflammation, including anemia of chronic kidney disease. A black box warning for EPO therapy and concerns about negative side effects related to high-dose iron supplementation as well as the significant proportion of patients becoming EPO resistant over time explains the medical need to define novel strategies to ameliorate anemia of chronic disease (ACD). As hepcidin is central to the iron-restrictive phenotype in ACD, therapeutic approaches targeting hepcidin were recently developed. We herein report the therapeutic effects of a fully human anti-BMP6 antibody (KY1070) either as monotherapy or in combination with Darbepoetin alfa on iron metabolism and anemia resolution in 2 different, well-established, and clinically relevant rodent models of ACD. In addition to counteracting hepcidin-driven iron limitation for erythropoiesis, we found that the combination of KY1070 and recombinant human EPO improved the erythroid response compared with either monotherapy in a qualitative and quantitative manner. Consequently, the combination of KY1070 and Darbepoetin alfa resulted in an EPO-sparing effect. Moreover, we found that suppression of hepcidin via KY1070 modulates ferroportin expression on erythroid precursor cells, thereby lowering potentially toxic-free intracellular iron levels and by accelerating erythroid output as reflected by increased maturation of erythrocyte progenitors. In summary, we conclude that treatment of ACD, as a highly complex disease, becomes more effective by a multifactorial therapeutic approach upon mobilization of endogenous iron deposits and stimulation of erythropoiesis.

Transferrin receptor regulates malignancies and the stemness of hepatocellular carcinoma-derived cancer stem-like cells by affecting iron accumulation

BACKGROUND

Iron metabolism is essential because it plays regulatory roles in various physiological and pathological processes. Disorders of iron metabolism balance are related to various cancers, including hepatocellular carcinoma. Cancer stem-like cells (CSCs) exert critical effects on chemotherapy failure, cancer metastasis, and subsequent disease recurrence and relapse. However, little is known about how iron metabolism affects liver CSCs. Here, we investigated the expression of transferrin receptor 1 (TFR1) and ferroportin (FPN), two iron importers, and an upstream regulator, iron regulatory protein 2 (IRP2), in liver hepatocellular carcinoma (LIHC) and related CSCs.

METHODS

The expression levels of TFR1, FPN and IRP2 were analysed using the GEPIA database. CSCs were derived from parental LIHC cells cultured in serum-free medium. After TFR1 knockdown, ROS accumulation and malignant behaviours were measured. The CCK-8 assay was performed to detect cell viability after TFR1 knockdown and erastin treatment.

RESULTS

TFR1 expression was upregulated in LIHC tissue and CSCs derived from LIHC cell lines, prompting us to investigate the roles of TFR1 in regulating CSCs. Knockdown of TFR1 expression decreased iron accumulation and inhibited malignant behaviour. Knockdown of TFR1 expression decreased reactive oxygen species (ROS) accumulation induced by erastin treatment and maintained mitochondrial function, indicating that TFR1 is critical in regulating erastin-induced cell death in CSCs. Additionally, knockdown of TFR1 expression decreased sphere formation by decreasing iron accumulation in CSCs, indicating a potential role for TFR1 in maintaining stemness.

CONCLUSION

These findings, which revealed TFR1 as a critical regulator of LIHC CSCs in malignant behaviour and stemness that functions by regulating iron accumulation, may have implications to improve therapeutic approaches.

Iron loss triggers mitophagy through induction of mitochondrial ferritin

Mitochondrial quality is controlled by the selective removal of damaged mitochondria through mitophagy. Mitophagy impairment is associated with aging and many pathological conditions. An iron loss induced by iron chelator triggers mitophagy by a yet unknown mechanism. This type of mitophagy may have therapeutic potential, since iron chelators are clinically used. Here, we aimed to clarify the mechanisms by which iron loss induces mitophagy. Deferiprone, an iron chelator, treatment resulted in the increased expression of mitochondrial ferritin (FTMT) and the localization of FTMT precursor on the mitochondrial outer membrane. Specific protein 1 and its regulator hypoxia-inducible factor 1α were necessary for deferiprone-induced increase in FTMT. FTMT specifically interacted with nuclear receptor coactivator 4, an autophagic cargo receptor. Deferiprone-induced mitophagy occurred selectively for depolarized mitochondria. Additionally, deferiprone suppressed the development of hepatocellular carcinoma (HCC) in mice by inducing mitophagy. Silencing FTMT abrogated deferiprone-induced mitophagy and suppression of HCC. These results demonstrate the mechanisms by which iron loss induces mitophagy and provide a rationale for targeting mitophagic activation as a therapeutic strategy.

Mitochondrion-mediated iron accumulation promotes carcinogenesis and Warburg effect through reactive oxygen species in osteosarcoma

Background

Iron metabolism disorder is closely associated with several malignant tumors, however the mechanisms underlying iron and the carcinogenesis in osteosarcoma are not yet well understood.

Methods

Cell proliferation ability of osteosarcoma cell lines was measured by CCK-8, EdU incorporation and colony formation assays. Cell cycle analysis was detected by flow cytometry. The carcinogenesis of osteosarcoma was measured by soft-agar formation, trans-well and Wound healing-scratch assay. Warburg effect was detected by Seahorse respirometry assays. Reactive oxygen species (ROS) level was measured by Dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescent probes. Western blotting was used to measure the expression of mitoferrin 1 (SLC25A37) and mitoferrin 2 (SLC25A28). Iron level in vitro and vivo was detected by iron assay kit. RNAi stable cell lines was generated using shRNA.

Results

Iron promoted proliferation, carcinogenesis and Warburg effect of osteosarcoma cells. Iron-induced reactive oxygen species (ROS) played an important role in these processes. Iron accumulated more in mitochondrion than in cytoplasm, suggesting mitochondrion-mediated iron accumulation was involved in the development of osteosarcoma. Moreover, iron upregulated the expression of mitoferrin 1 (SLC25A37) and mitoferrin 2 (SLC25A28). Knock-down of mitoferrin 1 (SLC25A37) and mitoferrin 2 (SLC25A28) decreased the production of ROS. In addition, iron increased the expression of Warburg key enzymes HK2 and Glut1, and affected AMPK/mTORC1 signaling axis.

Conclusions

Mitochondrion-mediated iron accumulation promotes carcinogenesis and Warburg effect of osteosarcoma cells. Meanwhile, iron deprivation might be a novel effective strategy in the treatment of osteosarcoma.

Friend or Foe? Recent Strategies to Target Myeloid Cells in Cancer

The tumor microenvironment (TME) is a complex network of epithelial and stromal cells, wherein stromal components provide support to tumor cells during all stages of tumorigenesis. Among these stromal cell populations are myeloid cells, which are comprised mainly of tumor-associated macrophages (TAM), dendritic cells (DC), myeloid-derived suppressor cells (MDSC), and tumor-associated neutrophils (TAN). Myeloid cells play a major role in tumor growth through nurturing cancer stem cells by providing growth factors and metabolites, increasing angiogenesis, as well as promoting immune evasion through the creation of an immune-suppressive microenvironment. Immunosuppression in the TME is achieved by preventing critical anti-tumor immune responses by natural killer and T cells within the primary tumor and in metastatic niches. Therapeutic success in targeting myeloid cells in malignancies may prove to be an effective strategy to overcome chemotherapy and immunotherapy limitations. Current therapeutic approaches to target myeloid cells in various cancers include inhibition of their recruitment, alteration of function, or functional re-education to an antitumor phenotype to overcome immunosuppression. In this review, we describe strategies to target TAMs and MDSCs, consisting of single agent therapies, nanoparticle-targeted approaches and combination therapies including chemotherapy and immunotherapy. We also summarize recent molecular targets that are specific to myeloid cell populations in the TME, while providing a critical review of the limitations of current strategies aimed at targeting a single subtype of the myeloid cell compartment. The goal of this review is to provide the reader with an understanding of the critical role of myeloid cells in the TME and current therapeutic approaches including ongoing or recently completed clinical trials.

The prognostic roles of red blood cell-associated indicators in patients with resectable gastric cancers

Background

Gastric cancer (GC) is one of the leading causes of cancer-related death worldwide. This study was designed to investigate the prognostic values of red blood cell (RBC)-associated indicators, including RBC, hemoglobin (HGB), hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and RBC distribution width (RDW) in resectable GC patients.

Methods

In this retrospective study, a total of 104 pathologically confirmed GC patients were recruited. These cases were divided into two groups according to the median values of pretreatment RBC, HGB, HCT, MCV, MCH, MCHC, or RDW. To evaluate the changes in RBC-associated indicators values after treatment, we introduced the concept of post-/pre-treatment ratios (≤1 suggested RBC, HGB, HCT, MCV, MCH, MCHC, or RDW values were not increased after therapy, while >1 represented those in increased levels).

Results

The lower pretreatment MCHC levels were correlated with worse overall survival (OS), while pretreatment levels of RBC, HGB, HCT, MCV, MCH, or RDW were not. The whole course of treatment (surgery plus adjuvant chemotherapy) significantly decreased the values of MCHC, and increased the values of MCV and RDW, whereas it had no obvious effects on the values of RBC, HGB, HCT, or MCH. Patients with post-/pre-treatment MCV ratio >1 had an increased survival ratio. Meanwhile, post-/pre-treatment RBC, HGB, HCT, MCH, MCHC, or RDW ratios were not correlated with outcomes. Multivariate Cox regression analysis revealed that the American Joint Committee on Cancer (AJCC) stage (III), and lower pretreatment MCHC levels were independent risk factors affecting OS. The receiver operating characteristic (ROC) curve analysis showed that an MCHC value of 341.98 g/L was the optimal cutoff value for prognosis, with a sensitivity of 58.3% and a specificity of 75.0%.

Conclusions

Pretreatment MCHC levels could become a potential prognostic factor for resectable GC.

Disparities in the Concentrations of Essential/Toxic Elements in the Blood and Scalp Hair of Lymphoma Patients and Healthy Subjects

Lymphoma is one of the fastest growing malignancies worldwide and imbalance in the concentrations of trace elements can play a significant role in the onset and progression of the disease. Selected essential and toxic elements (Fe, Zn, Cu, Mn, Ni, Cr, Cd and Pb) were analysed in the blood & scalp hair of lymphoma patients (n = 59 & 58, respectively) and controls (n = 61 & 60, respectively) by atomic absorption spectrometry. On the average, Ni, Cr, Cu and Cd revealed significantly higher contents in the blood and scalp hair of the patients than the controls (p < 0.05). The correlation study showed significantly diverse relationships among the elements in blood & scalp hair of the two donor groups. Variations in the elemental levels with different types of lymphoma (non-Hodgkin and Hodgkin) were also evaluated. Disparities in the elemental concentrations were also investigated for various types of non-Hodgkin (diffuse large B-cell lymphoma, follicular lymphoma and peripheral T-cell lymphoma) and Hodgkin lymphoma (mixed cellularity, nodular lymphocyte predominant and nodular sclerosing), as well as for different stages (I, II, III & IV) of the cancer. Multivariate statistical analysis showed considerably divergent associations of the elements in the patients and controls. The study indicated profound alteration of the elemental levels in the patients; it may be implicated in elemental-induced disorders including lymphoma.

Iron and Ferritin Deposition in the Ovarian Tissues of the Yellow Fever Mosquito (Diptera: Culicidae)

Dengue, yellow fever, and Zika are viruses transmitted by yellow fever mosquito, Aedes aegypti [Linnaeus (Diptera: Culicidae)], to thousands of people each year. Mosquitoes transmit these viruses while consuming a blood meal that is required for oogenesis. Iron, an essential nutrient from the blood meal, is required for egg development. Mosquitoes receive a high iron load in the meal; although iron can be toxic, these animals have developed mechanisms for dealing with this load. Our previous research has shown iron from the blood meal is absorbed in the gut and transported by ferritin, the main iron transport and storage protein, to the ovaries. We now report the distribution of iron and ferritin in ovarian tissues before blood feeding and 24 and 72 h post-blood meal. Ovarian iron is observed in specific locations. Timing post-blood feeding influences the location and distribution of the ferritin heavy-chain homolog, light-chain homolog 1, and light-chain homolog 2 in ovaries. Understanding iron deposition in ovarian tissues is important to the potential use of interference in iron metabolism as a vector control strategy for reducing mosquito fecundity, decreasing mosquito populations, and thereby reducing transmission rates of vector-borne diseases.

Ferroportin downregulation promotes cell proliferation by modulating the Nrf2-miR-17-5p axis in multiple myeloma

Recent findings demonstrate that aberrant downregulation of the iron-exporter protein, ferroportin (FPN1), is associated with poor prognosis and osteoclast differentiation in multiple myeloma (MM). Here, we show that FPN1 was downregulated in MM and that clustered regularly interspaced short palindromic repeat (CRISPR)-mediated FPN1 knockout promoted MM cell growth and survival. Using a microRNA target-scan algorithm, we identified miR-17-5p as an FPN1 regulator that promoted cell proliferation and cell cycle progression, and inhibited apoptosis—both in vitro and in vivo. miR-17-5p inhibited retarded tumor growth in a MM xenograft model. Moreover, restoring FPN1 expression at least partially abrogated the biological effects of miR-17-5p in MM cells. The cellular iron concentration regulated the expression of the iron-regulatory protein (IRP) via the 5′-untranslated region of IRP messenger RNA and modulated the post-transcriptional stability of FPN1. Bioinformatics analysis with subsequent chromatin immunoprecipitation-polymerase chain reaction and luciferase activity experiments revealed that the transcription factor Nrf2 drove FPN1 transcription through promoter binding and suppressed miR-17-5p (which also increased FPN1 expression). Nrf2-mediated FPN1 downregulation promoted intracellular iron accumulation and reactive oxygen species. Our study links FPN1 transcriptional and post-transcriptional regulation with MM cell growth and survival, and validates the prognostic value of FPN1 and its utility as a novel therapeutic target in MM.

Antioxidant Capacity and Cytotoxic Effects of Catechins and Resveratrol Oligomers Produced by Enzymatic Oxidation against T24 Human Urinary Bladder Cancer Cells

In this work the polymerization of catechin, epicatechin, and resveratrol was carried out through a peroxidase oxidation process in order to improve the biological activity of these phenolic compounds. The antioxidant activity of the oligomers was evaluated by their ability to scavenge reactive oxygen species (ROS) and their capacity to chelate metal ions Fe2+ and Cu2+. The antitumor effect of the oligomers was determined by their ability to induce toxicity in the T24 human bladder cancer cell line. By enzymatic peroxidase oxidation, it was possible to produce oligomers of catechin, epicatechin, and resveratrol with antioxidant capacity significantly higher than their preceding monomers. The ROS scavenging capacity of the oligomers was 20 times higher than that of the monomers, while the ability of the oligomers to chelate metal ions increased up to about 1000 times. Our data show the antitumor effect of the oligomers of catechin, epicatechin, and resveratrol in the T24 cell line, which was similar to that observed with cisplatin. Oligomers of catechin, epicatechin, and resveratrol have great potential to be used as therapeutic agents for the treatment of oxidative stress-related diseases and bladder cancer.

Desferrioxamine-caffeine shows improved efficacy in chelating iron and depleting cancer stem cells

Iron chelation has already been proposed to be a feasible strategy for cancer therapeutics in that reinforced iron demand is demonstrated in cancer cells, and quite a few iron chelators have been developed for this purpose. Desferrioxamine (DFO), an iron chelator approved by the U.S. Food and Drug Administration (FDA), has been extensively examined to remove extra iron. However, DFO has been found to harbor limited efficacies in combating cancer cells due to poor cellular permeability. In the current study, we synthesized the DFO derivative, named as desferrioxamine-caffeine dimer (DFCAF) by linking DFO to caffeine with high purity and excellent stability. Our data showed that DFCAF displayed greater cellular permeability to chelate intracellular iron in 4T1 breast cancer cells than DFO, posing more inhibition on cell growth and cellular motility/invasion. Importantly, DFCAF was uncovered to remarkably deplete cancer stem cells (CSCs), as characterized by the remarkable decrease of the CD44^+/high/CD24^-/low and ALDH^+/high subpopulation. In parallel, DFCAF was also found to greatly reverse epithelial-mesenchymal transition (EMT), suggesting the potential application to restrain tumor progression and metastasis. Collectively, these data unveiled the improved efficacy to target cancer cells and to deplete CSCs, thus opening a new path for better cancer therapeutics through iron chelation.

Iron and Ferritin Modulate MHC Class I Expression and NK Cell Recognition

The ability of pathogens to sequester iron from their host cells and proteins affects their virulence. Moreover, iron is required for various innate host defense mechanisms as well as for acquired immune responses. Therefore, intracellular iron concentration may influence the interplay between pathogens and immune system. Here, we investigated whether changes in iron concentrations and intracellular ferritin heavy chain (FTH) abundance may modulate the expression of Major Histocompatibility Complex molecules (MHC), and susceptibility to Natural Killer (NK) cell cytotoxicity. FTH downregulation, either by shRNA transfection or iron chelation, led to MHC surface reduction in primary cancer cells and macrophages. On the contrary, mouse embryonic fibroblasts (MEFs) from NCOA4 null mice accumulated FTH for ferritinophagy impairment and displayed MHC class I cell surface overexpression. Low iron concentration, but not FTH, interfered with IFN-γ receptor signaling, preventing the increase of MHC-class I molecules on the membrane by obstructing STAT1 phosphorylation and nuclear translocation. Finally, iron depletion and FTH downregulation increased the target susceptibility of both primary cancer cells and macrophages to NK cell recognition. In conclusion, the reduction of iron and FTH may influence the expression of MHC class I molecules leading to NK cells activation.

Cell Permeable Imidazole-Desferrioxamine Conjugates: Synthesis and In Vitro Evaluation

Desferrioxamine (DFO), a clinically approved iron chelator used for iron overload, is unable to chelate labile plasma iron (LPI) because of its limited cell permeability. Herein, alkyl chain modified imidazolium cations with varied hydrophobicities have been conjugated with DFO. The iron binding abilities and the antioxidant properties of the conjugates were found to be similar to DFO. The degree of cellular internalization was much higher in the octyl-imidazolium-DFO conjugate (IV) compared with DFO, and IV was able to chelate LPI in vitro. This opens up a new avenue in using N-alkyl imidazolium salts as a delivery vector for hydrophilic cell-impermeable drugs.

Iron metabolism and its contribution to cancer (Review)

Iron is an essential element for biological processes. Iron homeostasis is regulated through several mechanisms, from absorption by enterocytes to recycling by macrophages and storage in hepatocytes. Iron has dual properties, which may facilitate tumor growth or cell death. Cancer cells exhibit an increased dependence on iron compared with normal cells. Macrophages potentially deliver iron to cancer cells, resulting in tumor promotion. Mitochondria utilize cellular iron to synthesize cofactors, including heme and iron sulfur clusters. The latter is composed of essential enzymes involved in DNA synthesis and repair, oxidation‑reduction reactions, and other cellular processes. However, highly increased iron concentrations result in cell death through membrane lipid peroxidation, termed ferroptosis. Ferroptosis, an emerging pathway for cancer treatment, is similar to pyroptosis, apoptosis and necroptosis. In the present review, previous studies on the physiology of iron metabolism and its role in cancer are summarized. Additionally, the significance of iron regulation, and the association between iron homeostasis and carcinogenic mechanisms are discussed.

A recycling anti-transferrin receptor-1 monoclonal antibody as an efficient therapy for erythroleukemia through target up-regulation and antibody-dependent cytotoxic effector functions

Targeting transferrin receptor 1 (TfR1) with monoclonal antibodies is a promising therapeutic strategy in cancer as tumor cells often overexpress TfR1 and show increased iron needs. We have re-engineered six anti-human TfR1 single-chain variable fragment (scFv) antibodies into fully human scFv₂-Fcγ1 and IgG1 antibodies. We selected the more promising candidate (H7), based on its ability to inhibit TfR1-mediated iron-loaded transferrin internalization in Raji cells (B-cell lymphoma). The H7 antibody displayed nanomolar affinity for its target in both formats (scFv₂-Fcγ1 and IgG1), but cross-reacted with mouse TfR1 only in the scFv₂-Fc format. H7 reduced the intracellular labile iron pool and, contrary to what has been observed with previously described anti-TfR1 antibodies, upregulated TfR1 level in Raji cells. H7 scFv₂-Fc format elimination half-life was similar in FcRn knock-out and wild type mice, suggesting that TfR1 recycling contributes to prevent H7 elimination in vivo. In vitro, H7 inhibited the growth of erythroleukemia and B-cell lymphoma cell lines (IC₅₀ 0.1 µg/mL) and induced their apoptosis. Moreover, the Im9 B-cell lymphoma cell line, which is resistant to apoptosis induced by rituximab (anti-CD20 antibody), was sensitive to H7. In vivo, tumor regression was observed in nude mice bearing ERY-1 erythroleukemia cell xenografts treated with H7 through a mechanism that involved iron deprivation and antibody-dependent cytotoxic effector functions. Therefore, targeting TfR1 using the fully human anti-TfR1 H7 is a promising tool for the treatment of leukemia and lymphoma.

Transferrin receptors-targeting nanocarriers for efficient targeted delivery and transcytosis of drugs into the brain tumors: a review of recent advancements and emerging trends

Treatment of glioblastoma multiforme (GBM) is a predominant challenge in chemotherapy due to the existence of blood-brain barrier (BBB) which restricts delivery of chemotherapeutic agents to the brain together with the problem of drug penetration through hard parenchyma of the GBM. With the structural and mechanistic elucidation of the BBB under both physiological and pathological conditions, it is now viable to target central nervous system (CNS) disorders utilizing the presence of transferrin (Tf) receptors (TfRs). However, overexpression of these TfRs on the GBM cell surface can also help to avoid restrictions of GBM cells to deliver chemotherapeutic agents within the tumor. Therefore, targeting of TfR-mediated delivery could counteract drug delivery issues in GBM and create a delivery system that could cross the BBB effectively to utilize ligand-conjugated drug complexes through receptor-mediated transcytosis. Hence, approach towards successful delivery of antitumor agents to the gliomas has been making possible through targeting these overexpressed TfRs within the CNS and glioma cells. This review article presents a thorough analysis of current understanding on Tf-conjugated nanocarriers as efficient drug delivery system.

Established and Emerging Concepts to Treat Imbalances of Iron Homeostasis in Inflammatory Diseases

Inflammation, being a hallmark of many chronic diseases, including cancer, inflammatory bowel disease, rheumatoid arthritis, and chronic kidney disease, negatively affects iron homeostasis, leading to iron retention in macrophages of the mononuclear phagocyte system. Functional iron deficiency is the consequence, leading to anemia of inflammation (AI). Iron deficiency, regardless of anemia, has a detrimental impact on quality of life so that treatment is warranted. Therapeutic strategies include (1) resolution of the underlying disease, (2) iron supplementation, and (3) iron redistribution strategies. Deeper insights into the pathophysiology of AI has led to the development of new therapeutics targeting inflammatory cytokines and the introduction of new iron formulations. Moreover, the discovery that the hormone, hepcidin, plays a key regulatory role in AI has stimulated the development of several therapeutic approaches targeting the function of this peptide. Hence, inflammation-driven hepcidin elevation causes iron retention in cells and tissues. Besides pathophysiological concepts and diagnostic approaches for AI, this review discusses current guidelines for iron replacement therapies with special emphasis on benefits, limitations, and unresolved questions concerning oral versus parenteral iron supplementation in chronic inflammatory diseases. Furthermore, the review explores how therapies aiming at curing the disease underlying AI can also affect anemia and discusses emerging hepcidin antagonizing drugs, which are currently under preclinical or clinical investigation.

A Promising Biocompatible Platform: Lipid-Based and Bio-Inspired Smart Drug Delivery Systems for Cancer Therapy

Designing new drug delivery systems (DDSs) for safer cancer therapy during pre-clinical and clinical applications still constitutes a considerable challenge, despite advances made in related fields. Lipid-based drug delivery systems (LBDDSs) have emerged as biocompatible candidates that overcome many biological obstacles. In particular, a combination of the merits of lipid carriers and functional polymers has maximized drug delivery efficiency. Functionalization of LBDDSs enables the accumulation of anti-cancer drugs at target destinations, which means they are more effective at controlled drug release in tumor microenvironments (TMEs). This review highlights the various types of ligands used to achieve tumor-specific delivery and discusses the strategies used to achieve the effective release of drugs in TMEs and not into healthy tissues. Moreover, innovative recent designs of LBDDSs are also described. These smart systems offer great potential for more advanced cancer therapies that address the challenges posed in this research area.

The role of iron metabolism in cancer therapy focusing on tumor-associated macrophages

Iron is an essential micronutrient in mammalian cells for basic processes such as DNA synthesis, cell cycle progression, and mitochondrial activity. Macrophages play a vital role in iron metabolism, which is tightly linked to their phagocytosis of senescent and death erythrocytes. It is now recognized that the polarization process of macrophages determines the expression profile of genes associated with iron metabolism. Although iron metabolism is strictly controlled by physiology, cancer has recently been connected with disordered iron metabolism. Moreover, in the environment of cancer, tumor-associated macrophages (TAMs) exhibit an iron release phenotype, which stimulates tumor cell survival and growth. Usually, the abundance of TAMs in the tumor is implicated in poor disease prognosis. Therefore, important attention has been drawn toward the development of tumor immunotherapies targeting these TAMs focussing on iron metabolism and reprogramming polarized phenotypes. Although further systematic research is still required, these efforts are almost certainly valuable in the search for new and effective cancer treatments.

Lipid accumulation in human breast cancer cells injured by iron depletors

Background

Current insights into the effects of iron deficiency in tumour cells are not commensurate with the importance of iron in cell metabolism. Studies have predominantly focused on the effects of oxygen or glucose scarcity in tumour cells, while attributing insufficient emphasis to the inadequate supply of iron in hypoxic regions. Cellular responses to iron deficiency and hypoxia are interlinked and may strongly affect tumour metabolism.

Methods

We examined the morphological, proteomic, and metabolic effects induced by two iron chelators—deferoxamine (DFO) and di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT)—on MDA-MB-231 and MDA-MB-157 breast cancer cells.

Results

These chelators induced a cytoplasmic massive vacuolation and accumulation of lipid droplets (LDs), eventually followed by implosive, non-autophagic, and non-apoptotic death similar to methuosis. Vacuoles and LDs are generated by expansion of the endoplasmic reticulum (ER) based on extracellular fluid import, which includes unsaturated fatty acids that accumulate in LDs. Typical physiological phenomena associated with hypoxia are observed, such as inhibition of translation, mitochondrial dysfunction, and metabolic remodelling. These survival-oriented changes are associated with a greater expression of epithelial/mesenchymal transcription markers.

Conclusions

Iron starvation induces a hypoxia-like program able to scavenge nutrients from the extracellular environment, and cells assume a hypertrophic phenotype. Such survival strategy is accompanied by the ER-dependent massive cytoplasmic vacuolization, mitochondrial dysfunctions, and LD accumulation and then evolves into cell death. LDs containing a greater proportion of unsaturated lipids are released as a consequence of cell death. The consequence of the disruption of iron metabolism in tumour tissue and the effects of LDs on intercellular communication, cancer–inflammation axis, and immunity remain to be explored. Considering the potential benefits, these are crucial subjects for future mechanistic and clinical studies.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0737-z) contains supplementary material, which is available to authorized users.

Di-2-pyridylhydrazone Dithiocarbamate Butyric Acid Ester Exerted Its Proliferative Inhibition against Gastric Cell via ROS-Mediated Apoptosis and Autophagy

Diversified biological activities of dithiocarbamates have attracted widespread attention; improving their feature or exploring their potent action of mechanism is a hot topic in medicinal research. Herein, we presented a study on synthesis and investigation of a novel dithiocarbamate, DpdtbA (di-2-pyridylhydrazone dithiocarbamate butyric acid ester), on antitumor activity. The growth inhibition assay revealed that DpdtbA had important antitumor activity for gastric cancer (GC) cell lines (IC₅₀ = 4.2 ± 0.52 μM for SGC-7901, 3.80 ± 0.40 μM for MGC-803). The next study indicated that growth inhibition is involved in ROS generation in mechanism; accordingly, the changes in mitochondrial membrane permeability, apoptotic genes, cytochrome c, bax, and bcl-2 were observed, implying that the growth inhibition of DpdtbA is involved in ROS-mediated apoptosis. On the other hand, the upregulated p53 upon DpdtbA treatment implied that p53 could also mediate the apoptosis. Yet the excess generation of ROS induced by DpdtbA led to cathepsin D translocation and increase of autophagic vacuoles and LC3-II, demonstrating that autophagy was also a contributor to growth inhibition. Further investigation showed that DpdtbA could induce cell cycle arrest at the G1 phase. This clearly indicated the growth inhibition of DpdtbA was via triggering ROS formation and evoking p53 response, consequently leading to alteration in gene expressions that are related to cell survival.

Transcriptional regulation of chickpea ferritin CaFer1 influences its role in iron homeostasis and stress response

Ferritin, ubiquitous among all living organisms except yeast, exhibits iron-regulated expression. In plants, this regulation is applied through transcriptional control. Previous studies established the presence of two types of cis-acting elements in the promoter region: the iron regulatory element (FRE) in soybean and the iron-dependent regulatory sequence (IDRS) in maize and Arabidopsis. Adverse environmental conditions (e.g. water-deficit and oxidative stress) are known to modulate the expression of phytoferritin genes. In this study, we cloned and investigated the promoter sequence of a chickpea ferritin, designated CaFer1. Phylogenetic analysis of the CaFer1 promoter revealed its evolutionary relationship with other phytoferritins. The CaFer1 promoter exhibited several putative regulatory elements including two known transcription factor (TF) binding sites, Athb-1 and Myb.Ph. Electrophoretic mobility shift assay confirmed the sequence-specific binding of Athb-1 and Myb.Ph on the CaFer1 promoter. The TF-binding dynamics of CaFer1 showed high induction under conditions of iron-deficiency and water-deficit. We also demonstrated the possible interaction of CaFer1 with IRT1, a key component of the iron uptake system in plants, indicating its involvement in maintaining cellular iron levels. These results provide new insights into the underlying mechanisms of function of these interacting factors in CaFer1-mediated iron homeostasis and the stress response in plants.

Nuclear transcription factor Nrf2 suppresses prostate cancer cells growth and migration through upregulating ferroportin

VTo investigate the effect of nuclear transcription factor Nrf2 on the transcription of Ferroportin (FPN) in prostate cancer cells, and the regulation mechanisms of FPN on cell viability, migration and apoptosis of prostate cancer cells.Empty vectors, pEGFPC1-Nrf2, pEGFPC1-FPN, Si-FPN and Si-Nrf2 were transfected into prostate cancer cell line PC3. The expression of mRNA and protein were measured by real time-PCR (RT-PCR) and western blot. Cell viability, migration, cycle and apoptosis were tested by CCK-8 assay, wound healing and flow cytometry, respectively. The interaction between FPN and Nrf2 was confirmed by chromatin immunoprecipitation (CHIP) assay.The viability, migration and mitosis of PC3 cells could be repressed by over-expressed FPN, with decreased intracellular ferritin. The CHIP assay demonstrated that Nrf2 is one transcription factor of FPN and promotes its transcription. With the increase of Nrf2 in PC3 cells, the viability, migration ability and concentration of ferritin were suppressed, while the apoptosis rate was increased. The above effects were counteracted by down-regulating FPN.FPN could inhibit the prostate cancer cell viability, migration and mitosis, which is also related to a decrease of intracellular ferritin content. In conclusion, Nrf2 suppresses prostate cancer cells viability, migration, and mitosis through upregulating FPN.

Stable nanoconjugates of transferrin with alloyed quaternary nanocrystals Ag-In-Zn-S as a biological entity for tumor recognition

One way to limit the negative effects of anti-tumor drugs on healthy cells is targeted therapy employing functionalized drug carriers. Here we present a biocompatible and stable nanoconjugate of transferrin anchored to Ag-In-Zn-S quantum dots modified with 11-mercaptoundecanoic acid (Tf-QD) as a drug carrier versus typical anticancer drug, doxorubicin. Detailed investigations of Tf-QD nanoconjugates without and with doxorubicin by fluorescence studies and cytotoxic measurements showed that the biological activity of both the transferrin and doxorubicin was fully retained in the nanoconjugate. In particular, the intercalation capabilities of free doxorubicin versus ctDNA remained essentially intact upon its binding to the nanoconjugate. In order to evaluate these capabilities, we studied the binding constant of doxorubicin attached to Tf-QDs with ctDNA as well as the binding site size on the ctDNA molecule. The binding constant slightly decreased compared to that of free doxorubicin while the binding site size, describing the number of consecutive DNA lattice residues involved in the binding, increased. It was also demonstrated that the QDs alone and in the form of a nanoconjugate with Tf were not cytotoxic towards human non-small cell lung carcinoma (H460 cell line) and the tumor cell sensitivity of the DOX-Tf-QD nanoconjugate was comparable to that of doxorubicin alone.

Surface Functionalization and Targeting Strategies of Liposomes in Solid Tumor Therapy: A Review

Surface functionalization of liposomes can play a key role in overcoming the current limitations of nanocarriers to treat solid tumors, i.e., biological barriers and physiological factors. The phospholipid vesicles (liposomes) containing anticancer agents produce fewer side effects than non-liposomal anticancer formulations, and can effectively target the solid tumors. This article reviews information about the strategies for targeting of liposomes to solid tumors along with the possible targets in cancer cells, i.e., extracellular and intracellular targets and targets in tumor microenvironment or vasculature. Targeting ligands for functionalization of liposomes with relevant surface engineering techniques have been described. Stimuli strategies for enhanced delivery of anticancer agents at requisite location using stimuli-responsive functionalized liposomes have been discussed. Recent approaches for enhanced delivery of anticancer agents at tumor site with relevant surface functionalization techniques have been reviewed. Finally, current challenges of functionalized liposomes and future perspective of smart functionalized liposomes have been discussed.

Anticarcinogenic and metal chelation properties of novel hydroxybenzylidene-1-indanone derivatives in the U-251 glioblastoma cell line

A novel series of (Z)-2-(hydroxy(aryl)methylene)-2,3-dihydro-1H-indanone derivatives were designed, synthesized and evaluated as cytotoxic agents against six cancer cell lines.