BRAF mutations are associated with increased iron regulatory protein-2 expression in colorectal tumorigenesis

Transferrin receptor 1 promotes hepatocellular carcinoma progression and metastasis by activating the mTOR signaling pathway

BACKGROUND

Aberrant iron metabolism is commonly observed in multiple tumor types, including hepatocellular carcinoma (HCC). However, as the key regulator of iron metabolism involved in iron absorption, the role of transferrin receptor (TFRC) in HCC remains elusive.

METHODS

The mRNA and protein expression of TFRC were evaluated in paired HCC and adjacent non-tumor specimens. The correlation between TFRC level and clinicopathological features or prognostic significance was also analyzed. The role of TFRC on biological functions was finally studied in vitro and in vivo.

RESULTS

The TFRC level was remarkably upregulated in HCC tissues compared to paired peritumor tissues. Overexpressed TFRC positively correlated with serum alpha-fetoprotein, carcinoembryonic antigen, and poor tumor differentiation. Multivariate analysis demonstrated that upregulated TFRC was an independent predictive marker for poorer overall survival and disease-free survival in HCC patients. Loss of TFRC markedly impaired cell proliferation and migration in vitro and notably suppressed HCC growth and metastasis in vivo, while overexpression of TFRC performed an opposite effect. Mechanistically, the mTOR signaling pathway was downregulated with TFRC knockdown, and the mTOR agonist MHY1485 completely reversed the biological inhibition in HCC cells caused by TFRC knockdown. Furthermore, exogenous ferric citrate (FAC) or iron chelator reversed the changed biological functions and signaling pathway expression of HCC cells caused by TFRC knockdown or overexpression, respectively.

CONCLUSIONS

Our study indicates that TFRC exerts an oncogenic role in HCC and may become a promising therapeutic target to restrain HCC progression.

Integrated in vivo functional screens and multi-omics analyses identify α-2,3-sialylation as essential for melanoma maintenance

Glycosylation is a hallmark of cancer biology, and altered glycosylation influences multiple facets of melanoma growth and progression. To identify glycosyltransferases, glycans, and glycoproteins essential for melanoma maintenance, we conducted an in vivo growth screen with a pooled shRNA library of glycosyltransferases, lectin microarray profiling of benign nevi and melanoma patient samples, and mass spectrometry-based glycoproteomics. We found that α-2,3 sialyltransferases ST3GAL1 and ST3GAL2 and corresponding α-2,3-linked sialosides are upregulated in melanoma compared to nevi and are essential for melanoma growth in vivo and in vitro. Glycoproteomics revealed that glycoprotein targets of ST3GAL1 and ST3GAL2 are enriched in transmembrane proteins involved in growth signaling, including the amino acid transporter Solute Carrier Family 3 Member 2 (SLC3A2/CD98hc). CD98hc suppression mimicked the effect of ST3GAL1 and ST3GAL2 silencing, inhibiting melanoma cell proliferation. We found that both CD98hc protein stability and its pro-survival effect in melanoma are dependent upon α-2,3 sialylation mediated by ST3GAL1 and ST3GAL2. In summary, our studies reveal that α-2,3-sialosides functionally contribute to melanoma maintenance, supporting ST3GAL1 and ST3GAL2 as novel therapeutic targets in these tumors.

Article review: Brazilin as potential anticancer agent

Brazilin is the main compound in Caesalpinia sappan and Haematoxylum braziletto, which is identified as a homoisoflavonoid based on its molecular structure. These plants are traditionally used as an anti-inflammatory to treat fever, hemorrhage, rheumatism, skin problems, diabetes, and cardiovascular diseases. Recently, brazilin has increased its interest in cancer studies. Several findings have shown that brazilin has cytotoxic effects on colorectal cancer, breast cancer, lung cancer, multiple myeloma, osteosarcoma, cervical cancer, bladder carcinoma, also other cancers, along with numerous facts about its possible mechanisms that will be discussed. Besides its flavonoid content, brazilin is able to chelate metal ions. A study has proved that brazilin could be used as an antituberculosis agent based on its ability to chelate iron. This possible iron-chelating of brazilin and all the studies discussed in this review will lead us to the statement that, in the future, brazilin has the potency to be a chemo-preventive and anticancer agent. The article review aimed to determine the brazilin mechanism and pathogenesis of cancer.

Modulation of ferroptosis by non‑coding RNAs in cancers: Potential biomarkers for cancer diagnose and therapy

Ferroptosis is a recently discovered cell programmed death. Extensive researches have indicated that ferroptosis plays an essential role in tumorigenesis, development, migration and chemotherapy drugs resistance, which makes it become a new target for tumor therapy. Non-coding RNAs (ncRNAs) are considered to control a wide range of cellular processes by modulating gene expression. Recent studies have indicated that ncRNAs regulate the process of ferroptosis via various pathway to affect the development of cancer. However, the regulation network remains ambiguous. In this review, we outlined the major metabolic processes of ferroptosis and concluded the relationship between ferroptosis-related ncRNAs and cancer progression. In addition, the prospect of ncRNAs being new therapeutic targets and early diagnosis biomarkers for cancer by regulating ferroptosis were presented, and the possible obstacles were also predicted. This could help in discovering novel cancer early diagnostic methods and therapeutic approaches.

Iron metabolism in colorectal cancer: a balancing act

BACKGROUND

Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the second deadliest malignancy worldwide. Current dietary habits are associated with increased levels of iron and heme, both of which increase the risk of developing CRC. The harmful effects of iron overload are related to the induction of iron-mediated pro-tumorigenic pathways, including carcinogenesis and hyperproliferation. On the other hand, iron deficiency may also promote CRC development and progression by contributing to genome instability, therapy resistance, and diminished immune responses. In addition to the relevance of systemic iron levels, iron-regulatory mechanisms in the tumor microenvironment are also believed to play a significant role in CRC and to influence disease outcome. Furthermore, CRC cells are more prone to escape iron-dependent cell death (ferroptosis) than non-malignant cells due to the constitutive activation of antioxidant genes expression. There is wide evidence that inhibition of ferroptosis may contribute to the resistance of CRC to established chemotherapeutic regimens. As such, ferroptosis inducers represent promising therapeutic drugs for CRC.

CONCLUSIONS AND PERSPECTIVES

This review addresses the complex role of iron in CRC, particularly in what concerns the consequences of iron excess or deprivation in tumor development and progression. We also dissect the regulation of cellular iron metabolism in the CRC microenvironment and emphasize the role of hypoxia and of oxidative stress (e.g. ferroptosis) in CRC. Finally, we underline some iron-related players as potential therapeutic targets against CRC malignancy.

Knockdown of TFRC suppressed the progression of nasopharyngeal carcinoma by downregulating the PI3K/Akt/mTOR pathway

BACKGROUND

The transferrin receptor (TfR) encoded by TFRC gene is the main cellular iron importer. TfR is highly expressed in many cancers and is expected to be a promising new target for cancer therapy; however, its role in nasopharyngeal carcinoma (NPC) remains unknown.

METHODS

The TfR levels were investigated in NPC tissues and cell lines using immunohistochemistry and reverse transcription-quantitative polymerase chain reaction. Knockdown of TFRC using two siRNA to investigate the effects on intracellular iron level and biological functions, including proliferation by CKK-8 assay, colony formation, cell apoptosis and cell cycle by flow cytometry, migration and invasion, and tumor growth in vivo by nude mouse xenografts. RNA sequencing was performed to find possible mechanism after TFRC knockdown on NPC cells and further verified by western blotting.

RESULTS

TfR was overexpressed in NPC cell lines and tissues. Knockdown of TFRC inhibited cell proliferation concomitant with increased apoptosis and cell cycle arrest, and it decreased intracellular iron, colony formation, migration, invasion, and epithelial-mesenchymal transition in HK1-EBV cells. Western blotting showed that TFRC knockdown suppressed the levels of the iron storage protein FTH1, anti-apoptotic marker BCL-xL, and epithelial-mesenchymal transition markers. We confirmed in vivo that TFRC knockdown also inhibited NPC tumor growth and decreased Ki67 expression in tumor tissues of nude mouse xenografts. RNA sequencing and western blotting revealed that TFRC silencing inhibited the PI3K/Akt/mTOR signaling pathway.

CONCLUSIONS

These results indicated that TfR was overexpressed in NPC, and TFRC knockdown inhibited NPC progression by suppressing the PI3K/Akt/mTOR signaling pathway. Thus, TfR may serve as a novel biomarker and therapeutic target for NPC.

Iron metabolism in colorectal cancer

Iron, as one of the essential trace elements in the human body, is involved in a wide range of critical biochemical reactions and physiological processes, including the maintenance of the normal cell cycle, mitochondrial function, nucleotide metabolism, and immune response. In this context, iron is naturally associated with cancer occurrence. Cellular iron deficiency can induce apoptosis, however, iron can also engage in potentially harmful reactions that produce free radicals because of its capacity to gain and lose electrons. Studies suggest that dietary iron, particularly heme iron, may be one of the leading causes of colorectal cancer (CRC). Moreover, patients with CRC have abnormal iron absorption, storage, utilization, and exportation. Therefore, iron is crucial for the development and progression of CRC. Elaborating on the alterations in iron metabolism during the onset and advancement of CRC would help to further explain the role and mechanism of iron inside the body. Thus, we reviewed the alterations in numerous iron metabolism-related molecules and their roles in CRC, which may provide new clues between iron metabolism and CRC.

Iron metabolism, ferroptosis, and lncRNA in cancer: knowns and unknowns

Cancer cells undergo substantial metabolic alterations to sustain increased energy supply and uncontrolled proliferation. As an essential trace element, iron is vital for many biological processes. Evidence has revealed that cancer cells deploy various mechanisms to elevate the cellular iron concentration to accelerate proliferation. Ferroptosis, a form of cell death caused by iron-catalyzed excessive peroxidation of polyunsaturated fatty acids (PUFAs), is a promising therapeutic target for therapy-resistant cancers. Previous studies have reported that long noncoding RNA (lncRNA) is a group of critical regulators involved in modulating cell metabolism, proliferation, apoptosis, and ferroptosis. In this review, we summarize the associations among iron metabolism, ferroptosis, and ferroptosis-related lncRNA in tumorigenesis. This information will help deepen understanding of the role of lncRNA in iron metabolism and raise the possibility of targeting lncRNA and ferroptosis in cancer combination therapy.

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.

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.

IRON-MEDIATED EPIGENETIC ACTIVATION OF NRF2 TARGETS

The toxic effects of excess dietary iron within the colonic lumen are well documented, particularly in the context of Inflammatory Bowel Disease (IBD) and Colorectal Cancer (CRC). Proposed mechanisms that underpin iron-associated intestinal disease include: i) the pro-inflammatory and ROS-promoting nature of iron, ii) gene-expression alterations, and iii) intestinal microbial dysbiosis. However, to date no studies have examined the effect of iron on the colonic epigenome. Here we demonstrate that chronic iron exposure of colonocytes leads to significant hypomethylation of the epigenome. Bioinformatic analysis highlights a significant epigenetic effect on NRF2 (nuclear factor erythroid 2-related factor 2) pathway targets (including NAD(P)H Quinone Dehydrogenase 1 [NQO1] and Glutathione peroxidase 2 [GPX2]); this demethylating effect was validated and subsequent gene and protein expression quantified. These epigenetic modifications were not observed upon the diminishment of cellular lipid peroxidation with endogenous glutathione and the subsequent removal of iron. Additionally, the induction of TET1 expression was found post-iron treatment, highlighting the possibility of an oxidative-stress induction of TET1 and subsequent hypomethylation of NRF2 targets. In addition, a strong time dependence on the establishment of iron-orchestrated hypomethylation was found which was concurrent with the increase in the intracellular labile iron pool (LIP) and lipid peroxidation levels. These epigenetic changes were further validated in murine intestinal mucosa in models administered a chronic iron diet, providing evidence for the likelihood of dietary-iron mediated epigenetic alterations in vivo. Furthermore, significant correlations were found between NQO1 and GPX2 demethylation and human intestinal tissue iron-status, thus suggesting that these iron-mediated epigenetic modifications are likely in iron-replete enterocytes. Together, these data describe a novel mechanism by which excess dietary iron is able to alter the intestinal phenotype, which could have implications in iron-mediated intestinal disease and the regulation of ferroptosis.

Screening and Identification of Lujo Virus Entry Inhibitors From an Food and Drug Administration-Approved Drugs Library

Lujo virus (LUJV) belongs to the Old World (OW) genus Mammarenavirus (family Arenaviridae). It is categorized as a biosafety level (BSL) 4 agent. Currently, there are no U.S. Food and Drug Administration (FDA)-approved drugs or vaccines specifically for LUJV or other pathogenic OW mammarenaviruses. Here, a high-throughput screening of an FDA-approved drug library was conducted using pseudotype viruses bearing LUJV envelope glycoprotein (GPC) to identify inhibitors of LUJV entry. Three hit compounds, trametinib, manidipine, and lercanidipine, were identified as LUJV entry inhibitors in the micromolar range. Mechanistic studies revealed that trametinib inhibited LUJV GPC-mediated membrane fusion by targeting C410 [located in the transmembrane (TM) domain], while manidipine and lercanidipine inhibited LUJV entry by acting as calcium channel blockers. Meanwhile, all three hits extended their antiviral spectra to the entry of other pathogenic mammarenaviruses. Furthermore, all three could inhibit the authentic prototype mammarenavirus, lymphocytic choriomeningitis virus (LCMV), and could prevent infection at the micromolar level. This study shows that trametinib, manidipine, and lercanidipine are candidates for LUJV therapy and highlights the critical role of calcium in LUJV infection. The presented findings reinforce the notion that the key residue(s) located in the TM domain of GPC provide an entry-targeted platform for designing mammarenavirus inhibitors.

The Role of Iron in Cancer Progression

Iron is an essential trace element for the human body, and its deficiency or excess can induce a variety of biological processes. Plenty of evidences have shown that iron metabolism is closely related to the occurrence and development of tumors. In addition, iron plays an important role in cell death, which is very important for the development of potential strategies for tumor treatment. Here, we reviewed the latest research about iron metabolism disorders in various types of tumors, the functions and properties of iron in ferroptosis and ferritinophagy, and new opportunities for iron-based on treatment methods for tumors, providing more information regarding the prevention and treatment of tumors.

Systematic Review of Cancer Targeting by Nanoparticles Revealed a Global Association between Accumulation in Tumors and Spleen

Active targeting of nanoparticles toward tumors is one of the most rapidly developing topics in nanomedicine. Typically, this strategy involves the addition of cancer-targeting biomolecules to nanoparticles, and studies on this topic have mainly focused on the localization of such formulations in tumors. Here, the analysis of the factors determining efficient nanoparticle targeting and therapy, various parameters such as types of targeting molecules, nanoparticle type, size, zeta potential, dose, and the circulation time are given. In addition, the important aspects such as how active targeting of nanoparticles alters biodistribution and how non-specific organ uptake influences tumor accumulation of the targeted nanoformulations are discussed. The analysis reveals that an increase in tumor accumulation of targeted nanoparticles is accompanied by a decrease in their uptake by the spleen. There is no association between targeting-induced changes of nanoparticle concentrations in tumors and other organs. The correlation between uptake in tumors and depletion in the spleen is significant for mice with intact immune systems in contrast to nude mice. Noticeably, modulation of splenic and tumor accumulation depends on the targeting molecules and nanoparticle type. The median survival increases with the targeting-induced nanoparticle accumulation in tumors; moreover, combinatorial targeting of nanoparticle drugs demonstrates higher treatment efficiencies. Results of the comprehensive analysis show optimal strategies to enhance the efficiency of actively targeted nanoparticle-based medicines.

Effects of Vanadyl Complexes with Acetylacetonate Derivatives on Non-Tumor and Tumor Cell Lines

Vanadium has a good therapeutic potential, as several biological effects, but few side effects, have been demonstrated. Evidence suggests that vanadium compounds could represent a new class of non-platinum, metal antitumor agents. In the present study, we aimed to characterize the antiproliferative activities of fluorescent vanadyl complexes with acetylacetonate derivates bearing asymmetric substitutions on the β-dicarbonyl moiety on different cell lines. The effects of fluorescent vanadyl complexes on proliferation and cell cycle modulation in different cell lines were detected by ATP content using the CellTiter-Glo Luminescent Assay and flow cytometry, respectively. Western blotting was performed to assess the modulation of mitogen-activated protein kinases (MAPKs) and relevant proteins. Confocal microscopy revealed that complexes were mainly localized in the cytoplasm, with a diffuse distribution, as in podocyte or a more aggregate conformation, as in the other cell lines. The effects of complexes on cell cycle were studied by cytofluorimetry and Western blot analysis, suggesting that the inhibition of proliferation could be correlated with a block in the G2/M phase of cell cycle and an increase in cdc2 phosphorylation. Complexes modulated mitogen-activated protein kinases (MAPKs) activation in a cell-dependent manner, but MAPK modulation can only partly explain the antiproliferative activity of these complexes. All together our results demonstrate that antiproliferative effects mediated by these compounds are cell type-dependent and involve the cdc2 and MAPKs pathway.

The Associations of Dietary Iron Intake and the Transferrin Receptor (TFRC) rs9846149 Polymorphism with the Risk of Gastric Cancer: A Case-Control Study Conducted in Korea

Background: A positive association between a high iron intake and colorectal cancer has been identified; however, the effect of dietary iron on gastric cancer (GC) remains unclear. Here, we investigate whether dietary iron is related to GC risk and whether the transferrin receptor (TFRC) rs9846149 polymorphism modifies this association. Methods: A case–control study was designed to assess this association among 374 GC patients and 754 healthy controls. A self-administered questionnaire was used to collect information on demographics, medical history and lifestyle. Dietary iron intake was assessed using a semi-quantitative food frequency questionnaire. TFRC rs9846149 was genetically analyzed using the Affymetrix Axiom Exom 319 Array platform. Results: A higher total dietary iron was significantly associated with decreased GC risk [OR = 0.65 (0.45–0.94), p for trend = 0.018]. A similar association was observed with nonheme iron [OR = 0.64 (0.44–0.92), p for trend = 0.018]. Individuals with a major allele of TFRC rs9846149 (CC/GC) and higher intake of total iron had a significantly lower GC risk than those with a lower intake [OR = 0.60 (0.41–0.88), p interaction = 0.035]. Conclusion: Our findings show the protective effects of total dietary iron, especially nonheme iron, against GC risk, and this association can be modified by TFRC rs9846149.

Intravenous iron is non-inferior to oral iron regarding cell growth and iron metabolism in colorectal cancer associated with iron-deficiency anaemia

Oral iron promotes intestinal tumourigenesis in animal models. In humans, expression of iron transport proteins are altered in colorectal cancer. This study examined whether the route of iron therapy alters iron transport and tumour growth. Colorectal adenocarcinoma patients with pre-operative iron deficiency anaemia received oral ferrous sulphate (n = 15), or intravenous ferric carboxymaltose (n = 15). Paired (normal and tumour tissues) samples were compared for expression of iron loading, iron transporters, proliferation, apoptosis and Wnt signalling using immunohistochemistry and RT-PCR. Iron loading was increased in tumour and distributed to the stroma in intravenous treatment and to the epithelium in oral treatment. Protein and mRNA expression of proliferation and iron transporters were increased in tumours compared to normal tissues but there were no significant differences between the treatment groups. However, intravenous iron treatment reduced ferritin mRNA levels in tumours and replenished body iron stores. Iron distribution to non-epithelial cells in intravenous iron suggests that iron is less bioavailable to tumour cells. Therefore, intravenous iron may be a better option in the treatment of colorectal cancer patients with iron deficiency anaemia due to its efficiency in replenishing iron levels while its effect on proliferation and iron metabolism is similar to that of oral iron treatment.

Iron metabolism: pathophysiology and pharmacology

Iron is essential in many physiological processes, including DNA metabolism, oxygen transport, and cellular energy generation. Deregulated iron metabolism, which results in iron overload or iron deficiency, is observed in many different diseases. We here summarize recent progress in the pathophysiology and pharmacology of iron-overload diseases, such as hereditary hemochromatosis, as well as iron-deficiency disorders, which are typically associated with anemia. The role of iron in immunity and the connection between iron and cancer are also addressed. We finally summarize and discuss the current (pre-) clinical landscape of pharmacotherapies targeting key players involved in iron metabolism.

Iron homeostasis and disorders revisited in the sepsis

Sepsis is a life-threatening condition caused by a dysregulated host-response to inflammation, although it currently lacks a fully elucidated pathobiology. Iron is a crucial trace element that is essential for fundamental processes in both humans and bacteria. During sepsis, iron metabolism is altered, including increased iron transport and uptake into cells and decreased iron export. The intracellular sequestration of iron limits its availability to circulating pathogens, which serves as a conservative strategy against the pathogens. Although iron retention has been showed to have protective protect effects, an increase in labile iron may cause oxidative injury and cell death (e.g., pyroptosis, ferroptosis) as the condition progresses. Moreover, iron disorders are substantial and correlate with the severity of sepsis. This also suggests that iron may be useful as a diagnostic marker for evaluating the severity and predicting the outcome of the disease. Further knowledge about these disorders could help in evaluating how drugs targeting iron homeostasis can be optimally applied to improve the treatment of patients with sepsis. Here, we present a comprehensive review of recent advances in the understanding of iron metabolism, focusing on the regulatory mechanisms and iron-mediated injury in sepsis.

Harnessing molecular recognition for localized drug delivery

A grand challenge in drug delivery is providing the right dose, at the right anatomic location, for the right duration of time to maximize therapeutic efficacy while minimizing off-target toxicity and other deleterious side-effects. Two general modalities are receiving broad attention for localized drug delivery. In the first, referred to as "targeted accumulation", drugs or drug carriers are engineered to have targeting moieties that promote their accumulation at a specific tissue site from circulation. In the second, referred to as "local anchoring", drugs or drug carriers are inserted directly into the tissue site of interest where they persist for a specified duration of time. This review surveys recent advances in harnessing molecular recognition between proteins, peptides, nucleic acids, lipids, and carbohydrates to mediate targeted accumulation and local anchoring of drugs and drug carriers.

Iron: An Essential Element of Cancer Metabolism

Cancer cells undergo considerable metabolic changes to foster uncontrolled proliferation in a hostile environment characterized by nutrient deprivation, poor vascularization and immune infiltration. While metabolic reprogramming has been recognized as a hallmark of cancer, the role of micronutrients in shaping these adaptations remains scarcely investigated. In particular, the broad electron-transferring abilities of iron make it a versatile cofactor that is involved in a myriad of biochemical reactions vital to cellular homeostasis, including cell respiration and DNA replication. In cancer patients, systemic iron metabolism is commonly altered. Moreover, cancer cells deploy diverse mechanisms to increase iron bioavailability to fuel tumor growth. Although iron itself can readily participate in redox reactions enabling vital processes, its reactivity also gives rise to reactive oxygen species (ROS). Hence, cancer cells further rely on antioxidant mechanisms to withstand such stress. The present review provides an overview of the common alterations of iron metabolism occurring in cancer and the mechanisms through which iron promotes tumor growth.

Iron chelators in cancer therapy

Iron chelators have long been a target of interest as anticancer agents. Iron is an important cellular resource involved in cell replication, metabolism and growth. Iron metabolism is modulated in cancer cells reflecting their increased replicative demands. Originally, iron chelators were first developed for use in iron overload disorders, however, their potential as anticancer agents has been gaining increasing interest. This is due, in part, to the downstream effects of iron depletion such as the inhibition of proliferation through ribonucleotide reductase activity. Additionally, some chelators form redox active metal complexes with iron resulting in the production of reactive oxygen species and oxidative stress. Newer synthetic iron chelators such as Deferasirox, Triapine and di-2-pyridylketone-4,4,-dimethyl-3-thiosemicrbazone (Dp44mt) have improved pharmacokinetic properties over the older chelator Deferoxamine. This review examines and discusses the various iron chelators that have been trialled for cancer therapy including both preclinical and clinical studies. The successes and shortcomings of each of the chelators and their use in combination therapies are highlighted and future potential in the cancer therapy world is considered.

Altered Iron Metabolism and Impact in Cancer Biology, Metastasis, and Immunology

Iron is an essential nutrient that plays a complex role in cancer biology. Iron metabolism must be tightly controlled within cells. Whilst fundamental to many cellular processes and required for cell survival, excess labile iron is toxic to cells. Increased iron metabolism is associated with malignant transformation, cancer progression, drug resistance and immune evasion. Depleting intracellular iron stores, either with the use of iron chelating agents or mimicking endogenous regulation mechanisms, such as microRNAs, present attractive therapeutic opportunities, some of which are currently under clinical investigation. Alternatively, iron overload can result in a form of regulated cell death, ferroptosis, which can be activated in cancer cells presenting an alternative anti-cancer strategy. This review focuses on alterations in iron metabolism that enable cancer cells to meet metabolic demands required during different stages of tumorigenesis in relation to metastasis and immune response. The strength of current evidence is considered, gaps in knowledge are highlighted and controversies relating to the role of iron and therapeutic targeting potential are discussed. The key question we address within this review is whether iron modulation represents a useful approach for treating metastatic disease and whether it could be employed in combination with existing targeted drugs and immune-based therapies to enhance their efficacy.

Protein Expression of Cyclin B1, Transferrin Receptor, and Fibronectin Is Correlated with the Prognosis of Adrenal Cortical Carcinoma

BACKGROUND

Adrenal cortical carcinoma (ACC) is a rare cancer with a variable prognosis. Several prognostic factors of ACC have been previously reported, but a proteomic analysis has not yet been performed. This study aimed to investigate prognostic biomarkers for ACC using a proteomic approach.

METHODS

We used reverse-phase protein array data from The Cancer Proteome Atlas, and identified differentially expressed proteins in metastatic ACCs. Multivariate Cox regression analysis adjusted by age and staging was used for survival analysis, and the C-index and category-free net reclassification improvement (cfNRI) were utilized to evaluate additive prognostic value.

RESULTS

In 46 patients with ACC, cyclin B1, transferrin receptor (TfR1), and fibronectin were significantly overexpressed in patients with distant metastasis. In multivariate models, high expression of cyclin B1 and TfR1 was significantly associated with mortality (hazard ratio [HR], 6.13; 95% confidence interval [CI], 1.02 to 36.7; and HR, 6.59; 95% CI, 1.14 to 38.2; respectively), whereas high fibronectin expression was not (HR, 3.92; 95% CI, 0.75 to 20.4). Combinations of high cyclin B1/high TfR1, high cyclin B1/high fibronectin, and high TfR1/high fibronectin were strongly associated with mortality ([HR, 13.72; 95% CI, 1.89 to 99.66], [HR, 9.22; 95% CI, 1.34 to 63.55], and [HR, 18.59; 95% CI, 2.54 to 135.88], respectively). In reclassification analyses, cyclin B1, TfR1, fibronectin, and combinations thereof improved the prognostic performance (C-index, 0.78 to 0.82-0.86; cfNRI, all P values <0.05).

CONCLUSION

In ACC patients, the overexpression of cyclin B1, TfR1, and fibronectin and combinations thereof were associated with poor prognosis.

Iron in the Tumor Microenvironment

Cancer metabolism is a well-known target of cancer therapeutics. Classically, cancer metabolism has been studied in terms of the dependence of cancer cells on crucial metabolites, such as glucose and glutamine. But, the accumulating data show that iron metabolism in tumor microenvironment is also an important factor in preserving the survival of cancer cells. Cancer cells have a distinct phenotype of iron metabolism, which secures the much-needed iron for these metabolically active cells. In order to use this iron efficiently, cancer cells need to increase their iron supply and decrease iron loss. As recent research suggests, this is not only done by modifying the expression of iron-related proteins in cancer cells, but also by interaction of cancer cells with other cells from the tumor milieu. Tumor microenvironment is a dynamic environment characterized with intricate relationship between cancer cells, tumor-associated macrophages, fibroblasts, and other cells. Some of the mechanistic aspects of this relationship have been elucidated, while others are yet to be identified. In any case, identifying the details of the iron phenotype of the cells in tumor microenvironment presents with a new therapeutic opportunity to treat this deadly disease.

Reduced expression of ferroportin1 and ceruloplasmin predicts poor prognosis in adrenocortical carcinoma

INTRODUCTION

Iron metabolism is tightly controlled in human cells. Dysregulation of iron metabolism-related genes has been characterized as a promising prognostic biomarker in cancers. However, the expression patterns and prognostic roles of iron metabolism-related genes remain unknown in adrenocortical carcinoma (ACC).

OBJECTIVES

The primary objective of this study was to explore the expression patterns and prognostic roles of iron metabolism-related genes in ACC using publicly available datasets.

METHODS

In the present study, we compared the expression patterns of 36 iron metabolism-related genes between ACC tumors (n = 77) and normal adrenal tissues (n = 128) based on The Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) data. The associations between clinical variables (including survival rate and pathological stage) and expression levels of iron mentalism-related genes were further explored. All the bioinformatics analyses were performed using the GEPIA or the Metascape tool.

RESULTS

Twelve iron metabolism-related genes were differentially expressed between ACC tumors and normal controls. Among them, reduced expression levels of ferroportin1 (FPN1) and ceruloplasmin (CP) were significantly correlated with poor survival of ACC patients. Specially, the expression levels of FPN1 were negatively correlated with the pathological stages of ACC. A pan-cancer analysis characterized the reduced expression of FPN1 and CP as an ACC-specific signature among 33 types of cancers. Functional enrichment analysis suggested that both FPN1 and CP might be implicated in several immune processes.

CONCLUSION

Reduced expression of FPN1 and CP was identified as a potential signature for poor prognosis of ACC in this study. Mechanisms underlying the prognostic value of FPN1 or CP in ACC deserve further experimental investigation.

Iron and Cancer

This review explores the multifaceted role that iron has in cancer biology. Epidemiological studies have demonstrated an association between excess iron and increased cancer incidence and risk, while experimental studies have implicated iron in cancer initiation, tumor growth, and metastasis. The roles of iron in proliferation, metabolism, and metastasis underpin the association of iron with tumor growth and progression. Cancer cells exhibit an iron-seeking phenotype achieved through dysregulation of iron metabolic proteins. These changes are mediated, at least in part, by oncogenes and tumor suppressors. The dependence of cancer cells on iron has implications in a number of cell death pathways, including ferroptosis, an iron-dependent form of cell death. Uniquely, both iron excess and iron depletion can be utilized in anticancer therapies. Investigating the efficacy of these therapeutic approaches is an area of active research that promises substantial clinical impact.

HAMP Downregulation Contributes to Aggressive Hepatocellular Carcinoma via Mechanism Mediated by Cyclin4-Dependent Kinase-1/STAT3 Pathway

BACKGROUND

Hepcidin encoded by HAMP is vital to regulating proliferation, metastasis, and migration. Hepcidin is secreted specifically by the liver. This study sought to examine the functional role of hepcidin in hepatocellular carcinoma (HCC).

METHODS

Data in the Cancer Genome Atlas database was used to analyze HAMP expression as it relates to HCC prognosis. We then used the 5-ethynyl-20-deoxyuridine (EdU) incorporation assay, transwell assay, and flow cytometric analysis, respectively, to assess proliferation, migration, and the cell cycle. Gene set enrichment analysis (GSEA) was used to find pathways affected by HAMP.

RESULTS

HAMP expression was lower in hepatocellular carcinoma samples compared with adjacent normal tissue controls. Low HAMP expression was linked with a higher rate of metastasis and poor disease-free status. Downregulation of HAMP induced SMMC-7721 and HepG-2 cell proliferation and promoted their migration. HAMP could affect the cell cycle pathway and Western blotting, confirming that reduced HAMP levels activated cyclin-dependent kinase-1/stat 3 pathway.

CONCLUSION

Our findings indicate that HAMP functions as a tumor suppressor gene. The role of HAMP in cellular proliferation and metastasis is related to cell cycle checkpoints. HAMP could be considered as a diagnostic biomarker and targeted therapy in HCC.

Iron Metabolism in Cancer

Demanded as an essential trace element that supports cell growth and basic functions, iron can be harmful and cancerogenic though. By exchanging between its different oxidized forms, iron overload induces free radical formation, lipid peroxidation, DNA, and protein damages, leading to carcinogenesis or ferroptosis. Iron also plays profound roles in modulating tumor microenvironment and metastasis, maintaining genomic stability and controlling epigenetics. in order to meet the high requirement of iron, neoplastic cells have remodeled iron metabolism pathways, including acquisition, storage, and efflux, which makes manipulating iron homeostasis a considerable approach for cancer therapy. Several iron chelators and iron oxide nanoparticles (IONPs) has recently been developed for cancer intervention and presented considerable effects. This review summarizes some latest findings about iron metabolism function and regulation mechanism in cancer and the application of iron chelators and IONPs in cancer diagnosis and therapy.

Iron Metabolism in Prostate Cancer; From Basic Science to New Therapeutic Strategies

An increasing amount of research has recently strengthened the case for the existence of iron dysmetabolism in prostate cancer. It is characterized with a wide array of differential expression of iron-related proteins compared to normal cells. These proteins control iron entry, cellular iron distribution but also iron exit from prostate cells. Iron dysmetabolism is not an exclusive feature of prostate cancer cells, but it is observed in other cells of the tumor microenvironment. Disrupting the machinery that secures iron for prostate cancer cells can retard tumor growth and its invasive potential. This review unveils the current understanding of the ways that prostate cancer cells secure iron in the tumor milieu and how can we exploit this knowledge for therapeutic purposes.

Transferrin receptor 1 in cancer: a new sight for cancer therapy

Iron as an important element plays crucial roles in various physiological and pathological processes. Iron metabolism behaves in systemic and cellular two levels that usually are in balance conditions. The disorders of the iron metabolism balances relate with many kinds of diseases including Alzheimer's disease, osteoporosis and various cancers. In systemic iron metabolism that is regulated by hepcidin-ferroportin axis, plasma iron is bound with transferrin (TF) which has two high-affinity binding sites for ferric iron. The generic cellular iron metabolism consists of iron intake, utilization and efflux. During the iron intake process in generic cells, transferrin receptors (TFRs) act as the most important receptor mediated controls. TFR1 and TFR2 are two subtypes of TFRs those bind with iron-transferrin complex to facilitate iron into cells. TFR1 is ubiquitously expressed on the surfaces of generic cells, whereas TFR2 is specially expressed in liver cells. TFR1 has attracted more attention than TFR2 by having diverse functions in both invertebrates and vertebrates. Recently reports showed that TFR1 involved in many kinds of diseases including anemia, neurodegenerative diseases and cancers. Most importantly, TFR1 has been verified to be abnormally expressed in various cancers. Some experimental and clinical drugs and antibodies targeting TFR1 have showed strong anti-tumor effects, herein TFR1 probably become a potential molecular target for diagnosis and treatment for cancer therapy. This paper reviewed the research progresses of the roles of TFR1 in the tumorigenesis and cancer progression, the regulations of TFR1, and the therapeutic effects of targeting TFR1 on many kinds of cancers.

Alterations in Cellular Iron Metabolism Provide More Therapeutic Opportunities for Cancer

Iron is an essential element for the growth and proliferation of cells. Cellular iron uptake, storage, utilization and export are tightly regulated to maintain iron homeostasis. However, cellular iron metabolism pathways are disturbed in most cancer cells. To maintain rapid growth and proliferation, cancer cells acquire large amounts of iron by altering expression of iron metabolism- related proteins. In this paper, normal cellular iron metabolism and the alterations of iron metabolic pathways in cancer cells were summarized. Therapeutic strategies based on targeting the altered iron metabolism were also discussed and disrupting redox homeostasis by intracellular high levels of iron provides new insight for cancer therapy. Altered iron metabolism constitutes a promising therapeutic target for cancer therapy.

Thermodynamic and Kinetic Analyses of Iron Response Element (IRE)-mRNA Binding to Iron Regulatory Protein, IRP1

Comparison of kinetic and thermodynamic properties of IRP1 (iron regulatory protein1) binding to FRT (ferritin) and ACO2 (aconitase2) IRE-RNAs, with or without Mn²⁺, revealed differences specific to each IRE-RNA. Conserved among animal mRNAs, IRE-RNA structures are noncoding and bind Fe²⁺ to regulate biosynthesis rates of the encoded, iron homeostatic proteins. IRP1 protein binds IRE-RNA, inhibiting mRNA activity; Fe²⁺ decreases IRE-mRNA/IRP1 binding, increasing encoded protein synthesis. Here, we observed heat, 5 °C to 30 °C, increased IRP1 binding to IRE-RNA 4-fold (FRT IRE-RNA) or 3-fold (ACO2 IRE-RNA), which was enthalpy driven and entropy favorable. Mn²⁺ (50 µM, 25 °C) increased IRE-RNA/IRP1 binding (K_d) 12-fold (FRT IRE-RNA) or 6-fold (ACO2 IRE-RNA); enthalpic contributions decreased ~61% (FRT) or ~32% (ACO2), and entropic contributions increased ~39% (FRT) or ~68% (ACO2). IRE-RNA/IRP1 binding changed activation energies: FRT IRE-RNA 47.0 ± 2.5 kJ/mol, ACO2 IRE-RNA 35.0 ± 2.0 kJ/mol. Mn²⁺ (50 µM) decreased the activation energy of RNA-IRP1 binding for both IRE-RNAs. The observations suggest decreased RNA hydrogen bonding and changed RNA conformation upon IRP1 binding and illustrate how small, conserved, sequence differences among IRE-mRNAs selectively influence thermodynamic and kinetic selectivity of the protein/RNA interactions.

BRAF mutations are associated with increased iron regulatory protein-2 expression in colorectal tumorigenesis

A role for iron in carcinogenesis is supported by evidence that iron metabolism proteins are modulated in cancer progression. To date, however, the expression of iron regulatory protein‐2 (IRP2), which is known to regulate several iron metabolism proteins, has not been assessed in colorectal cancer. Expression of IRP2 was assessed by quantitative RT‐PCR and immunohistochemistry in human colorectal cancer tissue. By interrogating The Cancer Genome Atlas (TCGA) database, expression of IRP2 and transferrin receptor‐1 (TfR1) was assessed relative to common mutations that are known to occur in cancer. The impact of suppressing IRP2 on cellular iron metabolism was also determined by using siRNA and by using the MEK inhibitor trametinib. IRP2 was overexpressed in colorectal cancer compared to normal colonic mucosa and its expression was positively correlated with TfR1 expression. In addition, IRP2 expression was associated with mutations in BRAF. The MEK inhibitor trametinib suppressed IRP2 and this was associated with a suppression in TfR1 and the labile iron pool (LIP). Moreover, epidermal growth factor stimulation resulted in decreased ferritin expression and an increase in the LIP which were independent of IRP2. Results presented here suggest that ablating IRP2 provides a therapeutic platform for intervening in colorectal tumorigenesis.