Iron-induced tissue damage and cancer: the role of reactive oxygen species-free radicals

STEAP3 can predict the prognosis and shape the tumor microenvironment of clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is a common malignant tumor of the urinary system characterized by poor prognosis and difficult treatment. It has been reported that iron metabolism dysregulation is a common phenomenon in ccRCC and is closely related to the process of ccRCC. But still now, the exact function and underlying mechanisms of iron metabolism dysregulation in ccRCC have not been fully elucidated. In this study, we comprehensively investigated the prognostic value and potential role of STEAP3 (an iron metabolism-related gene) in ccRCC. STEAP3 is significantly up-regulated in ccRCC. High STEAP3 expression is associated with gender, hemoglobin level, pathological grade, tumor stage and significantly predicts an unfavorable prognosis of ccRCC patients. Functional enrichment analysis and evaluation of the tumor microenvironment indicated that STEAP3 was involved in the remodeling of tumor extracellular matrix and the shaping of an immune-suppressive tumor microenvironment to promote tumor metastasis and evade immune killing. Besides, the expression of STEAP3 is also associated with the expression of various immune checkpoint molecules and the IC50 of targeted drugs. Finally, we verified STEAP3 by RT-qPCR and IHC staining. In conclusion, we found that STEAP3 can serve as a candidate prognostic biomarker for ccRCC, and targeting STEAP3 and its biological processes may provide new references for the individualized treatment of ccRCC.

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.

Ferroptosis-Driven Nanotherapeutics to Reverse Drug Resistance in Tumor Microenvironment

Ferroptosis, characterized by iron-dependent lipid reactive oxygen species (ROS) accumulation, is non-apoptotic programmed cell death highly relevant to tumor development. It was found to manipulate oncogenes and resistant mutations of cancer cells via lipid metabolism pathways converging on phospholipid glutathione peroxidase (GPX4) that squanders lipid peroxides (L-OOH) to block the iron-mediated reactions of peroxides, thus rendering resistant cancer cells vulnerable to ferroptotic cell death. By accumulating ROS and lipid peroxidation (LPO) products to lethal levels in tumor microenvironment (TME), ferroptosis-driven nanotherapeutics show a superior ability of eradicating aggressive malignancies than traditional therapeutic modalities, especially for the drug-resistant tumors with high metastasis tendency. Moreover, Fenton reaction, inhibition of GPX-4, and exogenous regulation of LPO are three major therapeutic strategies to induce ferroptosis in cancer cells, which were generally applied in ferroptosis-driven nanotherapeutics. In this review, we elaborate current trends of ferroptosis-driven nanotherapeutics to reverse drug resistance of tumors in anticancer fields at the intersection of cancer biology, materials science, and chemistry. Finally, their challenges and perspectives toward feasible translational studies are spotlighted, which would ignite the hope of anti-resistant cancer treatment.

Potential Key Markers for Predicting the Prognosis of Gastric Adenocarcinoma Based on the Expression of Ferroptosis-Related lncRNA

Background. Gastric cancer is one of the most common malignant tumors, and it ranks third in global cancer-related mortality. This research was aimed at identifying new targeted treatments for gastric adenocarcinoma by constructing a ferroptosis-related lncRNA prognostic feature model. Methods. The gene expression profile and clinical data of gastric adenocarcinoma patients were downloaded from TCGA database. FerrDb database was used to determine the expression of iron death-related genes. We used R software to clean the TCAG gastric adenocarcinoma gene expression cohort and screen iron death-related differential genes and lncRNAs. The potential prognostic markers and immune infiltration characteristics were determined by constructing prognostic model and multivariate validation of lncRNA related to ferroptosis prognosis. Finally, the characteristics of immune infiltration were determined by immune correlation analysis. Results. We identified 26 ferroptosis-related lncRNAs with independent prognostic value. The Kaplan-Meier analysis identified high-risk lncRNAs associated with poor prognosis of STAD. The risk scoring model constructed by AC115619.1, AC005165.1, LINC01614, and AC002451.1 was better than traditional clinicopathological features. The 1-, 3-, and 5-year survival rates of STAD patients were predicted by the nomogram. GSEA reveals the oxidative respiration and tumor-related pathways in different risk groups. Immune analysis found significant differences in the expression of immune checkpoint-related genes TNFSF9, TNFSF4, and PDCD1LG2 between the two groups of patients. Meanwhile, there were significant differences in APC co stimulation, CCR, and checkpoint between the two groups. Conclusion. Based on the prognostic characteristics of ferroptosis-related lncRNAs, we identified the potential ferroptosis-related lncRNAs and immune infiltration characteristics in gastric adenocarcinoma, which will help provide new targeted treatments for gastric adenocarcinoma.

The Role of Ferric Nitrilotriacetate in Renal Carcinogenesis and Cell Death: From Animal Models to Clinical Implications

Iron is essential for cellular growth, and various ferroproteins and heme-containing proteins are involved in a myriad of cellular functions, such as DNA synthesis, oxygen transport, and catalytic reactions. As a consequence, iron deficiency causes pleiotropic effects, such as hypochromic microcytic anemia and growth disturbance, while iron overload is also deleterious by oxidative injury. To prevent the generation of iron-mediated reactive oxygen species (ROS), ferritin is synthesized to store excess iron in cells that are consistent with the clinical utility of the serum ferritin concentration to monitor the therapeutic effect of iron-chelation. Among the animal models exploring iron-induced oxidative stress, ferric nitrilotriacetate (Fe-NTA) was shown to initiate hepatic and renal lipid peroxidation and the development of renal cell carcinoma (RCC) after repeated intraperitoneal injections of Fe-NTA. Here, current understanding of Fe-NTA-induced oxidative stress mediated by glutathione-cycle-dependent iron reduction and the molecular mechanisms of renal carcinogenesis are summarized in combination with a summary of the relationship between the pathogenesis of human RCC and iron metabolism. In addition to iron-mediated carcinogenesis, the ferroptosis that is triggered by the iron-dependent accumulation of lipid peroxidation and is implicated in the carcinogenesis is discussed.

Basal Ganglia Iron Content Increases with Glioma Severity Using Quantitative Susceptibility Mapping: A Potential Biomarker of Tumor Severity

BACKGROUND AND PURPOSE

Gliomas have been found to alter iron metabolism and transport in ways that result in an expansion of their intracellular iron compartments to support aggressive tumor growth. This study used deep neural network trained quantitative susceptibility mapping to assess basal ganglia iron concentrations in glioma patients.

MATERIALS AND METHODS

Ninety-two patients with brain lesions were initially enrolled in this study and fifty-nine met the inclusion criteria. Susceptibility-weighted images were collected at 3.0 T and used to construct quantitative susceptibility maps via a deep neural network-based method. The regions of interest were manually drawn within basal ganglia structures and the mean voxel intensities were extracted and averaged across multiple slices. One-way ANCOVA tests were conducted to compare the susceptibility values of groups of patients based on tumor grade while controlling for age, sex, and tumor type.

RESULTS

The mean basal ganglia susceptibility for patients with grade IV tumors was higher than that for patients with grade II tumors (p = 0.00153) and was also higher for patients with grade III tumors compared to patients with grade II tumors (p = 0.020), after controlling for age, sex, and tumor type. Patient age influenced susceptibility values (p = 0.00356), while sex (p = 0.69) and tumor type (p = 0.11) did not.

CONCLUSIONS

The basal ganglia iron content increased with glioma severity. Basal ganglia iron levels may thus be a useful biomarker in glioma prognosis and treatment, especially with regard to iron-based cancer therapies.

Iron as spirit of life to share under monopoly

Any independent life requires iron to survive. Whereas iron deficiency causes oxygen insufficiency, excess iron is a risk for cancer, generating a double-edged sword. Iron metabolism is strictly regulated via specific systems, including iron-responsive element (IRE)/iron regulatory proteins (IRPs) and the corresponding ubiquitin ligase FBXL5. Here we briefly reflect the history of bioiron research and describe major recent advancements. Ferroptosis, a newly coined Fe(II)-dependent regulated necrosis, is providing huge impact on science. Carcinogenesis is a process to acquire ferroptosis-resistance and ferroptosis is preferred in cancer therapy due to immunogenicity. Poly(rC)-binding proteins 1/2 (PCBP1/2) were identified as major cytosolic Fe(II) chaperone proteins. The mechanism how cells retrieve stored iron in ferritin cores was unraveled as ferritinophagy, a form of autophagy. Of note, ferroptosis may exploit ferritinophagy during the progression. Recently, we discovered that cellular ferritin secretion is through extracellular vesicles (EVs) escorted by CD63 under the regulation of IRE/IRP system. Furthermore, this process was abused in asbestos-induced mesothelial carcinogenesis. In summary, cellular iron metabolism is tightly regulated by multi-system organizations as surplus iron is shared through ferritin in EVs among neighbor and distant cells in need. However, various noxious stimuli dramatically promote cellular iron uptake/storage, which may result in ferroptosis.

Ferroptosis resistance determines high susceptibility of murine A/J strain to iron-induced renal carcinogenesis

Cancer susceptibility is a critical factor in the understanding of carcinogenesis. Intraperitoneal (i.p.) injection of an iron chelate, ferric nitrilotriacetate (Fe‐NTA), produces hydroxyl radicals via Fenton reaction to induce ferroptosis in renal proximal tubules. Rats or mice subjected to repeated i.p. injections of Fe‐NTA develop renal cell carcinoma (RCC). To elucidate the molecular mechanisms that cause susceptibility to renal carcinogenesis, we first established an inter‐strain difference in the susceptibility to Fe‐NTA‐induced renal carcinogenesis in mice. Based on a previous observation of a low incidence of RCC with this model in C57BL/6J strain mice, we investigated A/J strain mice here, which demonstrated significantly higher susceptibility to Fe‐NTA‐induced renal carcinogenesis. Homozygous deletion of the Cdkn2a/2b tumor suppressor locus was detected for the first time in A/J strain mice. Focusing on ferroptosis and iron metabolism, we explored the mechanisms involved that lead to the difference in RCC development. We compared the protective responses in the kidney of A/J and C57BL/6J strains after Fe‐NTA treatment. After 3‐week Fe‐NTA treatment, A/J mice maintained higher levels of expression of glutathione peroxidase 4 and xCT (SLC7A11), leading to a lower level of lipid peroxidation. Simultaneously, A/J mice had decreased expression of transferrin receptor and increased expression of ferritin to greater degrees than C57BL/6 mice. After a single Fe‐NTA injection, higher levels of oxidative cell damage and cytosolic catalytic Fe(II) were observed in C57BL/6J mice, accompanied by a greater increase in lipocalin‐2. Lipocalin‐2 deficiency significantly decreased oxidative renal damage. Our results suggest that a genetic trait favoring ferroptosis resistance contributes to high susceptibility to Fe‐NTA‐induced RCC in A/J strain.

An innovative NRF2 nano-modulator induces lung cancer ferroptosis and elicits an immunostimulatory tumor microenvironment

Simultaneous targeting of both the tumor microenvironment and cancer cells by a single nanomedicine has not been reported to date. Here, we report the dual properties of zero-valent-iron nanoparticle (ZVI-NP) to induce cancer-specific cytotoxicity and anti-cancer immunity.

Methods: Cancer-specific cytotoxicity induced by ZVI-NP was determined by MTT assay. Mitochondria functional assay, immunofluorescence staining, Western blot, RT-qPCR, and ChIP-qPCR assays were used to dissect the mechanism underlying ZVI-NP-induced ferroptotic cancer cell death. The therapeutic potential of ZVI-NP was evaluated in immunocompetent mice and humanized mice. Immune cell profiles of allografts and ex vivo cultured immune cells were examined by flow cytometry analysis, RT-qPCR assay, and immunofluorescence.

Results: ZVI-NP caused mitochondria dysfunction, intracellular oxidative stress, and lipid peroxidation, leading to ferroptotic death of lung cancer cells. Degradation of NRF2 by GSK3/β-TrCP through AMPK/mTOR activation was enhanced in such cancer-specific ferroptosis. In addition, ZVI-NP attenuated self-renewal ability of cancer and downregulated angiogenesis-related genes. Importantly, ZVI-NP augmented anti-tumor immunity by shifting pro-tumor M2 macrophages to anti-tumor M1, decreasing the population of regulatory T cells, downregulating PD-1 and CTLA4 in CD8⁺ T cells to potentiate their cytolytic activity against cancer cells, while attenuating PD-L1 expression in cancer cells in vitro and in tumor-bearing immunocompetent mice. In particular, ZVI-NPs preferentially accumulated in tumor and lung tissues, leading to prominent suppression of tumor growth and metastasis.

Conclusions: This dual-functional nanomedicine established an effective strategy to synergistically induce ferroptotic cancer cell death and reprogram the immunosuppressive microenvironment, which highlights the potential of ZVI-NP as an advanced integrated anti-cancer strategy.

A CaO2 @Tannic Acid-FeIII Nanoconjugate for Enhanced Chemodynamic Tumor Therapy

Chemodynamic therapy (CDT) is an effective tumor treatment strategy in which Fe^II reacts with hydrogen peroxide (H₂ O₂ ) in tumor cells to produce highly toxic hydroxyl radical (^. OH) through the Fenton reaction. However, the content of endogenous H₂ O₂ in cells is limited, and the reaction between Fe^III and H₂ O₂ is inefficient, greatly limiting the efficiency of the Fenton reaction and reducing the effectiveness of tumor treatment. Therefore, in this work, we designed and synthesized a new type of nano-system (CaO₂ @TA-Fe^III ) for the enhanced CDT of tumors, in which the polyphenolic compound- tannic acid (TA) and Fe^III formed a TA-Fe nano-coating on the surface of calcium peroxide (CaO₂ ) nanospherical aggregates. When the CaO₂ @TA-Fe^III nanoconjugates reach the tumor site, the CaO₂ contained in the nanoconjugates produces H₂ O₂ after disintegration in tumor cells, and the carried TA rapidly reduces Fe^III to Fe^II , solving the two major shortcomings in CDT of (1) insufficient content of H₂ O₂ in cancer cells, and (2) low catalytic efficiency of the Fenton reaction. Additionally, the ^. OH produced in the Fenton reaction induces oxidative stress for the tumor cells, promoting the occurrence of the "calcium overload" process, and thereby accelerating the death of tumor cells. Experimental results in vitro and in vivo showed that CaO₂ @TA-Fe^III nanoconjugates can effectively kill cancer cells and display an excellent tumor therapeutic effect. We believe that the CaO₂ @TA-Fe^III nanoconjugates are a promising new nano-platform for highly effective tumor treatment.

The therapeutic potential of curcumin in alleviating N-diethylnitrosamine and iron nitrilotriacetate induced renal cell tumours in mice via inhibition of oxidative stress: Implications for cancer chemoprevention

This study was designed to reveal the protective effects of dietary supplementation of curcumin against renal cell tumours and oxidative stress induced by renal carcinogen iron nitrilotriacetate (Fe-NTA) in ddY male mice. The results showed that mice treated with a renal carcinogen, Fe-NTA, a 35% renal cell tumour incidence was noticed, whereas renal cell tumour occurrence was elevated to 80% in Fe-NTA promoted and N-diethylnitrosamine (DEN)-initiated mice as compared with saline- treated mice. No incidence of tumours has been observed in DEN-initiated non-promoted mice. Diet complemented with 0.5% and 1.0% curcumin fed prior to, during and after treatment with Fe-NTA in DEN-initiated animals, tumour incidence was reduced dose-dependently to about 45% and 30% respectively. Immunohistochemical studies also revealed the increased formation of 4-hydroxy-2-nonenal (HNE)-modified protein adducts and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in kidney tissue of mice treated with an intraperitoneal injection of Fe-NTA (6.0 mg Fe/kg body weight.). Furthermore, Fe-NTA treatment of mice also resulted in significant elevation of malondialdehyde (MDA), serum urea, and creatinine and decreases renal glutathione. However, the changes in most of these parameters were attenuated dose-dependently by prophylactic treatment of animals with 0.5% and 1% curcumin diet, this may be due to its antioxidative impact of curcumin. These results suggest that intake of curcumin is beneficial for the prevention of renal cell tumours and oxidative stress damage mediated by renal carcinogen, Fe-NTA.

A systematic review and meta-analysis on the association of serum and tumor tissue iron and risk of breast cancer

BACKGROUND

Some studies have investigated the effects of iron on breast carcinogenesis and reported different findings about the association between Fe and breast cancer risk. This study was conducted to estimate this effect using meta-analysis method.

METHODS

A total of 20 articles published between 1984 and 2017 worldwide were selected through searching PubMed, Scopus, Embase, Web of Science, and Cochrane Library. Keywords such Breast Cancer, Neoplasm, Trace elements, Iron, Breast tissue concentration, Plasma concentration, Scalp hair concentration, toenail concentration and their combination were used in the search.

RESULTS

The total number of participants was 4,110 individuals comprising 1,624 patients with breast cancer and 2,486 healthy subjects. Fe concentration was measured in the various subgroups in both case and control groups. There were significant correlations between Fe concentration and breast cancer in breast tissue subgroup (SMD: 0.67 [95% CI: 0.17 to 1.17; P=0.009]). Whereas, there was no meaningful difference in Fe status between women with and without breast cancer related to scalp hair and plasma subgroups; (SMD: -3.74 [95% CI: -7.58 to 0.10; P=0.056] and (SMD:-1.14[95% CI: -2.30 to 0.03; P=0.055], respectively.

CONCLUSION

The present meta-analysis indicated a positive and straight association between iron concentrations and risk of breast cancer but because of high heterogeneity we recommend more accurate future studies.

Quantitation of Apurinic/Apyrimidinic Sites in Isolated DNA and in Mammalian Tissue with a Reduced Level of Artifacts

The apurinic/apyrimidinic (AP) site is a common lesion of DNA damage. The levels of AP sites reported in the literature cover a wide range, which is primarily due to the artifactual generation or loss of AP sites during processing of the DNA. Herein, we have developed a method for quantitating AP sites with a largely reduced level of artifacts by derivatizing AP sites before DNA isolation. A rapid digestion of nuclear protein was performed to minimize enzymatic DNA repair, followed by direct derivatization of AP sites in the nuclear lysate with O-(pyridin-3-yl-methyl)hydroxylamine, yielding an oxime derivative that is stable through the subsequent DNA processing steps. Quantitation was done using highly selective and sensitive liquid chromatography-tandem mass spectrometry, with a limit of quantitation at 2.2 lesions per 10⁸ nucleotides (nts, 0.9 fmol on column). The method was applied in vivo to measure AP sites in rats undergoing oxidative stress [liver, 3.31 ± 0.47/10⁷ nts (dosed) vs 0.91 ± 0.06/10⁷ nts (control); kidney, 1.60 ± 0.07/10⁷ nts (dosed) vs 1.13 ± 0.12/10⁷ nts (control)]. The basal AP level was significantly lower than literature values. The method was also used to measure AP sites induced by the chemotherapeutic nitrogen mustard in vitro.

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.

Intracellular Fenton reaction based on mitochondria-targeted copper(ii)–peptide complex for induced apoptosis

Intracellular Fenton reaction-based mitochondria-targeted copper(ii)–peptide complex and Asc is developed for cancer cell treatment.

Cancer Treatment through Nanoparticle-Facilitated Fenton Reaction

Currently, cancer is the second largest cause of death worldwide and has reached critical levels. In spite of all the efforts, common treatments including chemotherapy, photodynamic therapy, and photothermal therapy suffer from various problems which limit their efficiency and performance. For this reason, different strategies are being explored which improve the efficiency of these traditional therapeutic methods or treat the tumor cells directly. One such strategy utilizing the Fenton reaction has been investigated by many groups for the possible treatment of cancer cells. This approach is based on the knowledge that high levels of hydrogen peroxide exist within cancer cells and can be used to catalyze the Fenton reaction, leading to cancer-killing reactive oxygen species. Analysis of the current literature has shown that, due to the diverse morphologies, different sizes, various chemical properties, and the tunable structure of nanoparticles, nanotechnology offers the most promising method to facilitate the Fenton reaction with cancer therapy. This review aims to highlight the use of the Fenton reaction using different nanoparticles to improve traditional cancer therapies and the emerging Fenton-based therapy, highlighting the obstacles, challenges, and promising developments in each of these areas.

Toxicity of iron oxide nanoparticles: Size and coating effects

Toxicological research of novel nanomaterials is a major developmental step of their clinical approval. Since iron oxide magnetic nanoparticles have a great potential in cancer treatment and diagnostics, the investigation of their toxic properties is very topical. In this paper we synthesized bovine serum albumin-coated iron oxide nanoparticles with different sizes and their polyethylene glycol derivative. To prove high biocompatibility of obtained nanoparticles the number of in vitro toxicological tests on human fibroblasts and U251 glioblastoma cells was performed. It was shown that albumin nanoparticles' coating provides a stable and biocompatible shell and prevents cytotoxicity of magnetite core. On long exposure times (48 hours), cytotoxicity of iron oxide nanoparticles takes place due to free radical production, but this toxic effect may be neutralized by using polyethylene glycol modification.

Quantitative proteomics identifies STEAP4 as a critical regulator of mitochondrial dysfunction linking inflammation and colon cancer

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder and is a major risk factor for colorectal cancer (CRC). Hypoxia is a feature of IBD and modulates cellular and mitochondrial metabolism. However, the role of hypoxic metabolism in IBD is unclear. Because mitochondrial dysfunction is an early hallmark of hypoxia and inflammation, an unbiased proteomics approach was used to assess the mitochondria in a mouse model of colitis. Through this analysis, we identified a ferrireductase: six-transmembrane epithelial antigen of prostate 4 (STEAP4) was highly induced in mouse models of colitis and in IBD patients. STEAP4 was regulated in a hypoxia-dependent manner that led to a dysregulation in mitochondrial iron balance, enhanced reactive oxygen species production, and increased susceptibility to mouse models of colitis. Mitochondrial iron chelation therapy improved colitis and demonstrated an essential role of mitochondrial iron dysregulation in the pathogenesis of IBD. To address if mitochondrial iron dysregulation is a key mechanism by which inflammation impacts colon tumorigenesis, STEAP4 expression, function, and mitochondrial iron chelation were assessed in a colitis-associated colon cancer model (CAC). STEAP4 was increased in human CRC and predicted poor prognosis. STEAP4 and mitochondrial iron increased tumor number and burden in a CAC model. These studies demonstrate the importance of mitochondrial iron homeostasis in IBD and CRC.

Iron and thiol redox signaling in cancer: An exquisite balance to escape ferroptosis

Epidemiological data indicate a constant worldwide increase in cancer mortality, although the age of onset is increasing. Recent accumulation of genomic data on human cancer via next-generation sequencing confirmed that cancer is a disease of genome alteration. In many cancers, the Nrf2 transcription system is activated via mutations either in Nrf2 or Keap1 ubiquitin ligase, leading to persistent activation of the genes with antioxidative functions. Furthermore, deep sequencing of passenger mutations is clarifying responsible cancer causative agent(s) in each case, including aging, APOBEC activation, smoking and UV. Therefore, it is most likely that oxidative stress is the principal initiating factor in carcinogenesis, with the involvement of two essential molecules for life, iron and oxygen. There is evidence based on epidemiological and animal studies that excess iron is a major risk for carcinogenesis, suggesting the importance of ferroptosis-resistance. Microscopic visualization of catalytic Fe(II) has recently become available. Although catalytic Fe(II) is largely present in lysosomes, proliferating cells harbor catalytic Fe(II) also in the cytosol and mitochondria. Oxidative stress catalyzed by Fe(II) is counteracted by thiol systems at different functional levels. Nitric oxide, carbon monoxide and hydrogen (per)sulfide modulate these reactions. Mitochondria generate not only energy but also heme/iron sulfur cluster cofactors and remain mostly dysfunctional in cancer cells, leading to Warburg effects. Cancer cells are under persistent oxidative stress with a delicate balance between catalytic iron and thiols, thereby escaping ferroptosis. Thus, high-dose L-ascorbate and non-thermal plasma as well as glucose/glutamine deprivation may provide additional benefits as cancer therapies over preexisting therapeutics.

Astaxanthin ameliorates ferric nitrilotriacetate-induced renal oxidative injury in rats

Daily intake of vegetables can reduce the risk of cancer and lifestyle-related diseases. However, supplementary intake of β-carotene alone has been reported to increase the risk of lung cancer in male cigarette smokers and people who were exposed to asbestos. The mechanism of the antioxidative properties of carotenoids in vivo, especially under oxidative stress conditions, still remains unclear. To investigate the antioxidant properties of dietary compounds, we examined the effects of chemically modified astaxanthin (Ax-C-8) using a rat model of ferric nitrilotriacetate (Fe-NTA)-induced renal oxidative injury. Ax-C-8 demonstrated lethally toxic effects on the rats in a dose-dependent manner. Following supplementation with Ax-C-8 (0.02%, w/w) for 30 days, the rats were euthanized 1, 4 and 24 h after injection of Fe-NTA. After 4 h, Ax-C-8 pretreatment suppressed the elevation of creatinine and blood urea nitrogen and protected the rats from renal tubular necrosis and the formation of 4-hydroxy-2-nonenal-modified proteins. After 24 h, pretreatment with Ax-C-8 maintained the renal antioxidant enzyme levels and renal tubules. Here, we demonstrate the antioxidant effects of Ax-C-8 against Fe-NTA-induced oxidative injury in rats receiving a regular diet. These data suggest that dietary intake of astaxanthin may be useful for the prevention of renal tubular oxidative damage.

Decorporation of Iron Metal Using Dialdehyde Cellulose-Deferoxamine Microcarrier

Deferoxamine iron chelator has a limited therapeutic index due to rapid clearance from blood and possesses dose-limiting toxicity. Therefore, an intravenous deferoxamine delivery system based on dialdehyde cellulose (DAC) polymer was developed and its efficacy and toxicity were tested in iron-overloaded animals. The amino groups of deferoxamine were conjugated to free aldehyde moieties of dialdehyde cellulose via Schiff base reaction to form dialdehyde cellulose-deferoxamine (DAC-DFO) conjugate and characterized by Fourier transform infrared spectrophotometer, scanning electron microscope, and X-ray diffraction. The toxicity of prepared formulation was analyzed by XTT cell viability assay and LD50 study in mice. The change in serum iron levels, after intravenous administration of formulation, was observed in iron-overloaded rats. The DAC-DFO conjugate was tagged with Tc-99m to study the blood kinetics and observe change in blood circulation time. DAC-DFO conjugate was dispersible in water at concentration ∼75 mg/ml. In vitro cytotoxicity assay and LD₅₀ study in mice indicated significantly enhanced safety of covalently bound deferoxamine (at >1000 mg/kg body weight compared to free drug at ∼270 mg/kg dose). A preliminary scintigraphy imaging and blood clearance study, with technetium-99m, indicated prolonged circulation of conjugated DFO in rabbit blood. A single dose of formulation injected into iron overloaded animals was found to maintain the normal serum iron levels until 10 days. The polymeric conjugate was effective in maintaining normal serum iron levels until 10 days at a dose of 100 mg/kg body weight.

Aberrations in the Iron Regulatory Gene Signature Are Associated with Decreased Survival in Diffuse Infiltrating Gliomas

Iron is a tightly regulated micronutrient with no physiologic means of elimination and is necessary for cell division in normal tissue. Recent evidence suggests that dysregulation of iron regulatory proteins may play a role in cancer pathophysiology. We use public data from The Cancer Genome Atlas (TCGA) to study the association between survival and expression levels of 61 genes coding for iron regulatory proteins in patients with World Health Organization Grade II-III gliomas. Using a feature selection algorithm we identified a novel, optimized subset of eight iron regulatory genes (STEAP3, HFE, TMPRSS6, SFXN1, TFRC, UROS, SLC11A2, and STEAP4) whose differential expression defines two phenotypic groups with median survival differences of 52.3 months for patients with grade II gliomas (25.9 vs. 78.2 months, p< 10⁻³), 43.5 months for patients with grade III gliomas (43.9 vs. 87.4 months, p = 0.025), and 54.0 months when considering both grade II and III gliomas (79.9 vs. 25.9 months, p < 10⁻⁵).

Nephrotoxicity and its prevention by catechin in ferric nitrilotriacetate promoted oxidative stress in rats

Intraperitoneal injection of ferric nitrilotriacetate (Fe-NTA) to rats and mice results in iron-induced free radical injury and cancer in kidneys. This study was designed to investigate the effect of catechin, a bioflavonoid with antioxidant potential, on Fe-NTA-induced nephrotoxicity in rats. Four groups were employed in the present study. Group I served as control group, Group II animals received Fe-NTA (8 mg iron/kg body weight i.p.), Group III animals were given 40 mg/kg catechin p.o. twice a day for 4 days and on the 5th day Fe-NTA was challenged, and Group IV animals received catechin alone for 4 days. Renal function was assessed by measuring plasma creatinine and blood urea nitrogen. The oxidative stress was measured by renal malondialdehyde levels, reduced glutathione levels and by enzymatic activity of catalase, glutathione reductase and superoxide dismutase. One hour after a single intraperitoneal (i.p.) injection of Fe-NTA (8 mg iron/kg), a marked deterioration of renal architecture, renal function and severe oxidative stress was observed. Pretreatment of animals with catechin markedly attenuated renal dysfunction, reduced elevated thiobarbituric acid reacting substances (TBARS), restored the depleted renal antioxidant enzymes and normalized the renal morphological alterations. These results clearly demonstrate the role of oxidative stress and its relation to renal dysfunction, and suggest a protective effect of catechin on Fe-NTA-induced nephrotoxicity in rats.

Potential of Alginate Encapsulated Ferric Saccharate Microemulsions to Ameliorate Iron Deficiency in Mice

Iron deficiency is one of the most prominent mineral deficiencies around the world, which especially affects large population of women and children. Development of new technologies to combat iron deficiency is on high demand. Therefore, we developed alginate microcapsule with encapsulated iron that had better oral iron bioavailability. Microcapsules containing iron with varying ratios of sodium alginate ferric(III)-saccharide were prepared using emulsification method. In vitro studies with Caco-2 cells suggested that newly synthesized microemulsions had better iron bioavailability as compared to commercially available iron dextran formulations. Ferrozine in vitro assay showed that alginate-encapsulated ferric galactose microemulsion (AFGM) had highest iron bioavailability in comparison to other four ferric saccharate microemulsions, namely AFGlM, AFMM, AFSM, and AFFM synthesized in our laboratory. Mice studies also suggested that AFGM showed higher iron absorption as indicated by increased serum iron, hemoglobin, and other hematopoietic measures with almost no toxicity at tested doses. Development of iron-loaded microemulsions leads to higher bioavailability of iron and can provide alternative strategies to treat iron deficiency.

Meta-Analysis of the Association between H63D and C282Y Polymorphisms in HFE and Cancer Risk

BACKGROUND

Previous studies suggested that the H63D and C282Y polymorphisms in the HFE genes were susceptible to many cancer types, nevertheless, the present results were inconclusive. Thus, the present study was aimed to evaluate the association between the HFE polymorphisms (H63D and C282Y) and cancer risk via meta-analysis.

MATERIALS AND METHODS

We retrieved PubMed, Google Scholar, Embase and Web of Science databases for all eligible studies up to April 1, 2015. All the statistical analysis was conducted by STATA 12.0.

RESULTS

Finally, a total of 20 publications including 24 case-control studies, comprising 6,524 cases and 31,080 controls for HFE-C282Y polymorphism and 19 publications including 21 case control studies, comprising 5,648 cases and 14,257 controls for HFE-H63D polymorphism were enrolled in our analysis. An increased risk for overall cancer risk was identified in HFE-H63D polymorphism under allele contrast (D vs H: OR=1.153; 95%CI=1.031- 1.289, Pheterogeneity=0.002), homozygotes vs wide type (DD vs HH: OR=1.449; 95%CI=1.182-1.777, Pheterogeneity=0.391), dominant model (DD+HD vs HH: OR=1.145; 95%CI=1.007-1.301, Pheterogeneity=0.002) and recessive model (DD vs HD+HH: OR=1.416 ; 95%CI=1.156-1.735, Pheterogeneity=0.549), as well as HFE- C282Y under homozygotes vs wide type (YY vs CC: OR=1.428, 95%CI=1.017-2.006, Pheterogeneity=0.220). In addition, in the stratified analysis by cancer type, an increased risk was identified in hepatocellular carcinoma and breast cancer in C282Y polymorphism, as well as pancreatic cancer in H63D polymorphism, whereas a decreased risk of colorectal cancer was identified in C282Y polymorphism.

CONCLUSIONS

Present study suggested that H63D and C282Y polymorphisms associated with an increased risk of overall cancer. Nevertheless, well- designed study with large sample size will be continued on this issue of interest.

STAMP2 increases oxidative stress and is critical for prostate cancer

The six transmembrane protein of prostate 2 (STAMP2) is an androgen-regulated gene whose mRNA expression is increased in prostate cancer (PCa). Here, we show that STAMP2 protein expression is increased in human PCa compared with benign prostate that is also correlated with tumor grade and treatment response. We also show that STAMP2 significantly increased reactive oxygen species (ROS) in PCa cells through its iron reductase activity which also depleted NADPH levels. Knockdown of STAMP2 expression in PCa cells inhibited proliferation, colony formation, and anchorage-independent growth, and significantly increased apoptosis. Furthermore, STAMP2 effects were, at least in part, mediated by activating transcription factor 4 (ATF4), whose expression is regulated by ROS. Consistent with in vitro findings, silencing STAMP2 significantly inhibited PCa xenograft growth in mice. Finally, therapeutic silencing of STAMP2 by systemically administered nanoliposomal siRNA profoundly inhibited tumor growth in two established preclinical PCa models in mice. These data suggest that STAMP2 is required for PCa progression and thus may serve as a novel therapeutic target.

The Many Virtues of tRNA-derived Stress-induced RNAs (tiRNAs): Discovering Novel Mechanisms of Stress Response and Effect on Human Health

In mammalian cells, mature tRNAs are cleaved by stress-activated ribonuclease angiogenin to generate 5'- and 3'-tRNA halves: a novel class of small non-coding RNAs of 30-40 nucleotides in length. The biogenesis and biological functions of tRNA halves are emerging areas of research. This review will discuss the most recent findings on: (i) the mechanism and regulation of their biogenesis, (ii) their mechanism of action (we will specifically discuss their role in the protein synthesis inhibition and the intrinsic pathway of apoptosis), and (iii) their effects on the human physiology and disease conditions.

Cancer cells with irons in the fire

Iron is essential for the growth and proliferation of cells, as well as for many biological processes that are important for the maintenance and survival of the human body. However, excess iron is associated with the development of cancer and other pathological conditions, due in part to the pro-oxidative nature of iron and its damaging effects on DNA. Current studies suggest that iron depletion may be beneficial for patients that have diseases associated with iron overload or other iron metabolism disorders that may increase the risk for cancer. On the other hand, studies suggest that cancer cells are more vulnerable to the effects of iron depletion and oxidative stress in comparison to normal cells. Therefore, cancer patients might benefit from treatments that alter both iron metabolism and oxidative stress. This review highlights the pro-oxidant effects of iron, the relationship between iron and cancer development, the vulnerabilities of the iron-dependent cancer phenotype, and how these characteristics may be exploited to prevent or treat cancer.

Accumulation of metals in cancerous and healthy tissues of patients with lung cancer in Southern Poland

The aim of this study was to investigate whether the concentrations of metals differ among patients with and without lung cancer with different smoking status and living in industrialized environments. We also evaluated the relationships between metals and blood parameters including hematocrit level (Hct), hemoglobin concentration (Hb), red (RBC) and white (WBC) blood cells numbers. Concentrations of metals were measured with AAS (copper - Cu, iron - Fe, magnesium - Mg, zinc - Zn) and CV-AAS (mercury - Hg). Neither smoking status nor industrialization could be considered as a significant factor for metals accumulation in blood, lungs and tumor tissues, with the exception of mercury which differed in the aspect of industrialization. According to the type of the disease, Fe, Hg and Mg concentrations differed significantly in lungs. Correlations between metals and blood parameters were observed. Additionally, concentrations of Mg, Cu and Zn were correlated between lungs and tumor tissue of patients with cancer as well as they all were related to each other in lungs, tumor and blood tissues.

Iron and thiols as two major players in carcinogenesis: friends or foes?

Iron is the most abundant metal in the human body and mainly works as a cofactor for proteins such as hemoglobin and various enzymes. No independent life forms on earth can survive without iron. However, excess iron is intimately associated with carcinogenesis by increasing oxidative stress via its catalytic activity to generate hydroxyl radicals. Biomolecules with redox-active sulfhydryl function(s) (thiol compounds) are necessary for the maintenance of mildly reductive cellular environments to counteract oxidative stress, and for the execution of redox reactions for metabolism and detoxification. Involvement of glutathione S-transferase and thioredoxin has long attracted the attention of cancer researchers. Here, I update recent findings on the involvement of iron and thiol compounds during carcinogenesis and in cancer cells. It is now recognized that the cystine/glutamate transporter (antiporter) is intimately associated with ferroptosis, an iron-dependent, non-apoptotic form of cell death, observed in cancer cells, and also with cancer stem cells; the former with transporter blockage but the latter with its stabilization. Excess iron in the presence of oxygen appears the most common known mutagen. Ironically, the persistent activation of antioxidant systems via genetic alterations in Nrf2 and Keap1 also contributes to carcinogenesis. Therefore, it is difficult to conclude the role of iron and thiol compounds as friends or foes, which depends on the quantity/distribution and induction/flexibility, respectively. Avoiding further mutation would be the most helpful strategy for cancer prevention, and myriad of efforts are being made to sort out the weaknesses of cancer cells.

Mouse divalent metal transporter 1 is a copper transporter in HEK293 cells

Divalent Metal Transporter 1 (DMT1) is an apical Fe transporter in the duodenum and is involved in endosomal Fe export. Four protein isoforms have been described for DMT1, two from mRNA with an iron responsive element (IRE) and two from mRNA without it. The sets of two begin in exon 1A or 2. We have characterized copper transport using mouse 2/-IRE DMT1 during regulated ectopic expression. HEK293 cells carrying a TetR:Hyg element were stably transfected with pDEST31 containing a 2/-IRE construct. (64)Cu(1+) incorporation in doxycycline treated cells exhibited 18.6 and 30.0-fold increases in Cu content, respectively when were exposed to 10 and 100 μM of extracellular Cu. Cu content was ~4-fold above that of parent cells or cells carrying just the vector. (64)Cu uptake in transfected cells pre-incubated with 5 μM of Cu-His revealed a Vmax and Km of 11.98 ± 0.52 pmol mg protein(-1) min(-1) and 2.03 ± 0.03 μM, respectively. Doxycycline-stimulated Cu uptake was linear with time. The rates of apical Cu uptake decreased and transepithelial transport increased when intracellular Cu increased. The optimal pH for Cu transport was 6.5; uptake of Cu was temperature dependent. Silver does not inhibit Cu uptake in cells carrying the vector. In conclusion, Cu uptake in HEK293 cells that over-expressed the 2/-IRE isoform of DMT1 transporter supports our earlier contention that DMT1 transports Cu as Cu(1+).

Naringin accelerates the regression of pre-neoplastic lesions and the colorectal structural reorganization in a murine model of chemical carcinogenesis

The aim of this study was to investigate the effect of Naringin on pre-neoplastic colorectal lesions induced by chemical carcinogen in rats. Female Wistar rats weighing 130.8±27.1 g received weekly one subcutaneous injection of 1,2-dimethylhydrazine (DMH, 20 mg/kg) for 10 weeks. The animals were divided into 5 groups with 6 animals in each group. Group 1: 0.9% saline; Group 2: DMH+0.9% saline; Group 3: DMH+Naringin (10 mg/kg); Group 4: DMH+Naringin (100 mg/kg); Group 5: DMH+Naringin (200 mg/kg). G2 and G3 showed a significant increase in ACF number, AgNOR/nucleus and mitosis compared to G1. G4 and G5 presented a significant reduction in these parameters compared to G2. The number of cells producing acidic and neutral mucins, red blood cells and the level of antioxidant minerals, such as copper, magnesium, selenium and zinc, were significantly reduced in G2 and G3, but similar in G4 and G5 compared to G1. Naringin, especially at 200 mg/kg, was effective in reducing the number of pre-neoplastic lesions in rats exposed to DMH. Some of these effects may be due to reduction in cellular proliferation and tissue levels of iron together with the recovery of antioxidant mineral levels induced by this flavonoid.

Iron overload as a major targetable pathogenesis of asbestos-induced mesothelial carcinogenesis

Few people expected that asbestos, a fibrous mineral, would be carcinogenic to humans. In fact, asbestos is a definite carcinogen in humans, causing a rare but aggressive cancer called malignant mesothelioma (MM). Mesothelial cells line the three somatic cavities and thus do not face the outer surface, but reduce the friction among numerous moving organs. MM has several characteristics: extremely long incubation period of 30-40 years after asbestos exposure, difficulty in clinical diagnosis at an early stage, and poor prognosis even under the current multimodal therapies. In Japan, 'Kubota shock' attracted considerable social attention in 2005 for asbestos-induced mesothelioma and, thereafter, the government enacted a law to provide the people suffering from MM a financial allowance. Several lines of recent evidence suggest that the major pathology associated with asbestos-induced MM is local iron overload, associated with asbestos exposure. Preclinical studies to prevent MM after asbestos exposure with iron reduction are in progress. In addition, novel target genes in mesothelial carcinogenesis have been discovered with recently recognized mesothelioma-prone families. Development of an effective preventive strategy is eagerly anticipated because of the long incubation period for MM.

Effect of Nerium oleander (N.O.) leaves extract on serum hepcidin, total iron, and infiltration of ED1 positive cells in albino rat

To gain insight into the hepatohistological alterations in noninjured rat liver, Nerium oleander (N.O.) leaves extract was injected intramuscularly to induce an acute phase reaction (APR). Histopathological changes were studied after 3, 12, and 24 h time course of sterile muscle abscess. Tissue integrity and any infiltration of inflammatory cells in the liver were investigated by Hematoxylin and Eosin and ED1 peroxidase stainings. The administration of N.O. leaves extract (10 mL/kg) in H & E stained sections showed a general vacuolization of cytoplasm resulting loss of polarity with prominent nucleoli after 3 h of induction. At 12 h, eccentric nuclei were also observed in the sections. Marked infiltration of leucocytes with predominate macrophages was also found after 24 h as seen by ED1 positive staining. In the present study, a possible relationship between serum hepcidin and total iron level was also investigated in vivo. An early increase of hepcidin and total iron level (3 h) with a maximum at 12 h (P < 0.01; P < 0.001) was observed. These changes indicate that sterile muscle abscess may induce APR resulting in hepatic damage which is evident with the recruitment of inflammatory cells into the organ.

Iron regulator hepcidin exhibits antiviral activity against hepatitis C virus

Hepatitis C viral infection affects 170 million people worldwide. It causes serious chronic liver diseases. HCV infection has been implicated in iron accumulation in the liver and iron overload has been shown to be a potential cofactor for HCV associated hepatocellular carcinoma progression. The underlying mechanisms are not understood. Human hepcidin, a 25 amino acid peptide mainly produced by hepatocytes, is a key regulator of iron metabolism. Alteration of hepcidin expression levels has been reported in the setting of chronic HCV infection and hepatocellular carcinoma. In this study, we aim to examine the interactions between HCV infection and hepcidin expression in liver cells. We found that hepcidin expression was suppressed in HCV infected cells. The suppressive effect appears to be regulated by histone acetylation but not DNA methylation. Moreover, we found that hepcidin had a direct antiviral activity against HCV replication in cell culture. The antiviral effect is associated with STAT3 activation. In conclusion, hepcidin can induce intracellular antiviral state while HCV has a strategy to suppress hepcidin expression. This may be a novel mechanism by which HCV circumvents hepatic innate antiviral defense.

Deferiprone reduces amyloid-β and tau phosphorylation levels but not reactive oxygen species generation in hippocampus of rabbits fed a cholesterol-enriched diet

Accumulation of amyloid-β (Aβ) peptide and the hyperphosphorylation of tau protein are major hallmarks of Alzheimer's disease (AD). The causes of AD are not well known but a number of environmental and dietary factors are suggested to increase the risk of developing AD. Additionally, altered metabolism of iron may have a role in the pathogenesis of AD. We have previously demonstrated that cholesterol-enriched diet causes AD-like pathology with iron deposition in rabbit brain. However, the extent to which chelation of iron protects against this pathology has not been determined. In this study, we administered the iron chelator deferiprone in drinking water to rabbits fed with a 2% cholesterol diet for 12 weeks. We found that deferiprone (both at 10 and 50 mg/kg/day) significantly decreased levels of Aβ40 and Aβ42 as well as BACE1, the enzyme that initiates cleavage of amyloid-β protein precursor to yield Aβ. Deferiprone also reduced the cholesterol diet-induced increase in phosphorylation of tau but failed to reduce reactive oxygen species generation. While deferiprone treatment was not associated with any change in brain iron levels, it was associated with a significant reduction in plasma iron and cholesterol levels. These results demonstrate that deferiprone confers important protection against hypercholesterolemia-induced AD pathology but the mechanism(s) may involve reduction in plasma iron and cholesterol levels rather than chelation of brain iron. We propose that adding an antioxidant therapy to deferiprone may be necessary to fully protect against cholesterol-enriched diet-induced AD-like pathology.

The neglected significance of "antioxidative stress"

Oxidative stress arises when there is a marked imbalance between the production and removal of reactive oxygen species (ROS) in favor of the prooxidant balance, leading to potential oxidative damage. ROSs were considered traditionally to be only a toxic byproduct of aerobic metabolism. However, recently, it has become apparent that ROS might control many different physiological processes such as induction of stress response, pathogen defense, and systemic signaling. Thus, the imbalance of the increased antioxidant potential, the so-called antioxidative stress, should be as dangerous as well. Here, we synthesize increasing evidence on “antioxidative stress-induced” beneficial versus harmful roles on health, disease, and aging processes. Oxidative stress is not necessarily an un-wanted situation, since its consequences may be beneficial for many physiological reactions in cells. On the other hand, there are potentially harmful effects of “antioxidative stress,” especially in the cases of overconsumption of synthetic antioxidants. Antioxidants can neutralize ROS and decrease oxidative stress; however, this is not always beneficial in regard to disease formation or progression (of, e.g., cancer) or for delaying aging.

Literature review of the role of hydroxyl radicals in chemically-induced mutagenicity and carcinogenicity for the risk assessment of a disinfection system utilizing photolysis of hydrogen peroxide

We have developed a new disinfection system for oral hygiene, proving that hydroxyl radicals generated by the photolysis of 1 M hydrogen peroxide could effectively kill oral pathogenic microorganisms. Prior to any clinical testing, the safety of the system especially in terms of the risk of carcinogenicity is examined by reviewing the literature. Previous studies have investigated indirectly the kinds of reactive oxygen species involved in some sort of chemically-induced mutagenicity in vitro by using reactive oxygen species scavengers, suggesting the possible involvement of hydroxyl radicals. Similarly, possible involvement of hydroxyl radicals in some sort of chemically-induced carcinogenicity has been proposed. Notably, it is suggested that the hydroxyl radical can play a role in heavy metal-induced carcinogenicity that requires chronic exposure to the carcinogen. In these cases, hydroxyl radicals produced by Fenton-like reactions may be involved in the carcinogenicity. Meanwhile, potential advantages have been reported on the use of the hydroxyl radical, being included in host immune defense by polymorphonuclear leukocytes, and medical applications such as for cancer treatment and antibiotics. From these, we conclude that there would seem to be little to no risk in using the hydroxyl radical as a disinfectant for short-term treatment of the oral cavity.

Chemopreventive effect of cactus Opuntia ficus indica on oxidative stress and genotoxicity of aflatoxin B1

BACKGROUND

Aflatoxin B1 (AFB1) is potent hepatotoxic and hepatocarcinogenic agent. In aflatoxicosis, oxidative stress is a common mechanism contributing to initiation and progression of hepatic damage. The aim of this work was to evaluate the hepatoprotective effect of cactus cladode extract (CCE) on aflatoxin B1-induced liver damage in mice by measuring malondialdehyde (MDA) level, the protein carbonyls generation and the heat shock proteins Hsp 70 and Hsp 27 expressions in liver. We also looked for an eventual protective effect against AFB1-induced genotoxicity as determined by chromosome aberrations test, SOS Chromotest and DNA fragmentation assay. We further evaluated the modulation of p53, bax and bcl2 protein expressions in liver.

METHODS

Adult, healthy balbC (20-25 g) male mice were pre-treated by intraperitonial administration of CCE (50 mg/Kg.b.w) for 2 weeks. Control animals were treated 3 days a week for 4 weeks by intraperitonial administration of 250 μg/Kg.b.w AFB1. Animals treated by AFB1 and CCE were divided into two groups: the first group was administrated CCE 2 hours before each treatment with AFB1 3 days a week for 4 weeks. The second group was administrated without pre-treatment with CCE but this extract was administrated 24 hours after each treatment with AFB1 3 days a week for 4 weeks.

RESULTS

Our results clearly showed that AFB1 induced significant alterations in oxidative stress markers. In addition, it has a genotoxic potential and it increased the expression of pro apoptotic proteins p53 and bax and decreased the expression of bcl2. The treatment of CCE before or after treatment with AFB1, showed (i) a total reduction of AFB1 induced oxidative damage markers, (ii) an anti-genotoxic effect resulting in an efficient prevention of chromosomal aberrations and DNA fragmentation compared to the group treated with AFB1 alone (iii) restriction of the effect of AFB1 by differential modulation of the expression of p53 which decreased as well as its associated genes such as bax and bcl2.

CONCLUSION

We concluded that CCE might have a hepatoprotective effect against aflatoxicosis in mice, probably acting by promoting the antioxidant defence systems.

A beverage containing fermented black soybean ameliorates ferric nitrilotriacetate-induced renal oxidative damage in rats

It is beneficial to seek scientific basis for the effects of functional foods. Natural pigments derived from plants are widely known as possible antioxidants. Black soybean contains a larger amount of anthocyanins than regular soybean. Here we studied the antioxidative effect of a beverage obtained via citric acid fermentation of black soybean (BBS), using a rat model of renal oxidative injury induced by a renal carcinogen, ferric nitrilotriacetate. BBS (10 ml/kg) was orally administered 30 min before ferric nitrilotriacetate treatment. Renal lipid peroxidation was significantly suppressed in the BBS-pretreated animals concomitant with decrease in 4-hydroxy-2-nonenal-modified proteins and 8-hydroxy-2'-deoxyguanosine. Maintenance of renal activities of antioxidative enzymes including catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase, glucose-6-phosphate dehydrogenase and quinone reductase was significantly better in the BBS-pretreated rats. Elevation of serum creatinine and urea nitrogen was significantly suppressed in the BBS-pretreated rats. These data suggest that dietary intake of BBS is useful for the prevention of renal tubular oxidative damage mediate by iron, and warrant further investigation.

The role of iron in the pathophysiology and treatment of chronic hepatitis C

Increased hepatic iron content may be observed in patients with chronic hepatitis C infection, and may contribute to disease severity. The presence of hemochromatosis gene mutations is associated with increased hepatic iron accumulation and may lead to accelerated disease progression. Hepatic iron depletion has been postulated to decrease the risk of hepatocellular carcinoma in patients with cirrhosis due to chronic hepatitis C. It is possible that iron depletion stabilizes or improves liver histology and slows disease progression in these individuals. The present article reviews the prevalence and risk factors for hepatic iron overload in chronic hepatitis C, with emphasis on the available data regarding the efficacy of iron depletion in the treatment of this common liver disease.

Effect of tocotrienols on iron-induced renal dysfunction and oxidative stress in rats

Ferric nitrilotriacetate (Fe-NTA) is a well-established nephrotoxic agent. This study was designed to investigate the modulatory effect of the subacute administration of tocotrienol-rich fraction (T3), a product from palm oil, and alpha-tocopherol (T) on Fe-NTA-induced renal injury and oxidative stress. Fe-NTA administration markedly increased blood urea nitrogen (BUN) and serum creatinine level, which was coupled with a marked lipid peroxidation, reduced activity of glutathione levels, and morphological alterations in rat kidney. Pretreatment with T3 (50 mg/kg/day) and T (50 mg/kg/day) for 7 days before Fe-NTA administration significantly reduced the serum creatinine and BUN levels, reduced lipid peroxidation in a significant manner, and restored levels of reduced glutathione and superoxide dismutase. T3 pretreatment also attenuated the serum tumor necrosis factor-alpha levels, as compared to pretreatment with T, and restored normal renal morphology. These findings suggest a strong correlation between iron-induced oxidative stress and renal dysfunction and point toward the protective effects of T3 in Fe-NTA-induced renal injury.