Arsenic and chromium in drinking water promote tumorigenesis in a mouse colitis-associated colorectal cancer model and the potential mechanism is ROS-mediated Wnt/β-catenin signaling pathway

Pollution of four heavy metal elements in dried chili peppers in Guizhou Province and its health risk assessment

This study aimed to evaluate arsenic (As), cadmium (Cd), chromium (Cr), and lead (Pb) levels in dried chili peppers from nine districts in Guizhou Province. These heavy metals, widely dispersed and capable of transferring to crops, pose potential health risks to humans. The assessment included modeling daily intake (EDI), target hazard quotient (THQ), total target hazard index (TTHQ), and target carcinogenic risk (TCR) to assess health risks across different population groups. Results showed chromium (0.9540 ± 0.301 mg/kg) and lead (0.8949 ± 0.266 mg/kg) had the highest concentrations, followed by arsenic (0.3287 ± 0.093 mg/kg) and cadmium (0.0627 ± 0.017 mg/kg). Children exhibited higher EDI values than adults, indicating greater health risks from dried chili pepper consumption at equivalent levels. THQ and TTHQ values were below 1 across all regions, indicating no significant health risks associated with dried chili pepper consumption. Similarly, TCR values were below 10-4 for all nine regions, indicating an acceptable level of carcinogenic risk. Overall, consuming dried chili peppers in Guizhou Province poses an acceptable health risk, but caution is advised, especially for children, to limit heavy metal exposure.

Role of an interdependent Wnt, GSK3-β/β-catenin and HB-EGF/EGFR mechanism in arsenic-induced hippocampal neurotoxicity in adult mice

We previously reported the neurotoxic effects of arsenic in the hippocampus. Here, we explored the involvement of Wnt pathway, which contributes to neuronal functions. Administering environmentally relevant arsenic concentrations to postnatal day-60 (PND60) mice demonstrated a dose-dependent increase in hippocampal Wnt3a and its components, Frizzled, phospho-LRP6, Dishevelled and Axin1 at PND90 and PND120. However, p-GSK3-β(Ser9) and β-catenin levels although elevated at PND90, decreased at PND120. Additionally, treatment with Wnt-inhibitor, rDkk1, reduced p-GSK3-β(Ser9) and β-catenin at PND90, but failed to affect their levels at PND120, indicating a time-dependent link with Wnt. To explore other underlying factors, we assessed epidermal growth factor receptor (EGFR) pathway, which interacts with GSK3-β and appears relevant to neuronal functions. We primarily found that arsenic reduced hippocampal phosphorylated-EGFR and its ligand, Heparin-binding EGF-like growth factor (HB-EGF), at both PND90 and PND120. Moreover, treatment with HB-EGF rescued p-GSK3-β(Ser9) and β-catenin levels at PND120, suggesting their HB-EGF/EGFR-dependent regulation at this time point. Additionally, rDkk1, LiCl (GSK3-β-activity inhibitor), or β-catenin protein treatments induced a time-dependent recovery in HB-EGF, indicating potential inter-dependent mechanism between hippocampal Wnt/β-catenin and HB-EGF/EGFR following arsenic exposure. Fluorescence immunolabeling then validated these findings in hippocampal neurons. Further exploration of hippocampal neuronal survival and apoptosis demonstrated that treatment with rDkk1, LiCl, β-catenin and HB-EGF improved Nissl staining and NeuN levels, and reduced cleaved-caspase-3 levels in arsenic-treated mice. Supportively, we detected improved Y-Maze and Passive Avoidance performances for learning-memory functions in these mice. Overall, our study provides novel insights into Wnt/β-catenin and HB-EGF/EGFR pathway interaction in arsenic-induced hippocampal neurotoxicity.

Hexavalent chromium causes centrosome amplification by inhibiting the binding between TMOD2 and NPM2

BACKGROUND

Hexavalent chromium can promote centrosome amplification (CA) as well as tumorigenesis. Since CA can lead to tumorigenesis, it is plausible that the chromium promotes the development of cancer via CA. In the present study, we investigated the signaling pathways of the chromium-induced CA.

RESULTS

Our results showed that sub-toxic concentration of chromium was able to cause CA in HCT116 cells, and decrease the expression of TMOD2 and NPM2. Furthermore, TMOD2 and NPM2 interacted to each other via their C-terminal and the N-terminal, respectively, which was inhibited by the chromium. Overexpression of TMOD2 and NPM2 increased their binding and significantly attenuated the CA. Moreover, TMOD2 and NPM2 were co-localized with the centrosomes. The chromium inhibited the centrosomeal localization of NPM2, which was reversed by the overexpression of TMOD2, C-terminal of TMOD2, but not the N-terminal of NPM2.

CONCLUSION

Our results suggest that the chromium induces CA via inhibiting the binding between TMOD2 and NPM2 as well as the dissociation of NPM2 from centrosomes.

AVAILABILITY OF DATA AND MATERIALS

The data and materials are available from the corresponding authors.

Malignant growth of arsenic-transformed cells depends on activated Akt induced by reactive oxygen species

Arsenic is an identified carcinogen for humans.In this study, chronic exposure of human hepatocyte L-02 to low-doses of inorganic arsenic caused cell malignant proliferation. Meanwhile, compared with normal L-02 cells, arsenic-transformed malignant cells, L-02-As displayed more ROS and significantly higher Cyclin D1 expression as well as aerobic glycolysis. Moreover, Akt activation is followed by the upregulation of Cyclin D1 and HK2 expression in L-02-As cells, since inhibition of Akt activity by Ly294002 attenuated the colony formation in soft agar and decreased the levels of Cyclin D1 and HK2. In addition, scavenging of ROS by NAC resulted in a decreased expression of phospho-Akt, HK2 and Cyclin D1, and attenuates the ability of anchorage-independent growth ofL-02-As cells, suggested that ROS mediated the Akt activation in L-02-As cells. In summary, our results demonstrated that ROS contributes to the malignant phenotype of arsenic-transformed human hepatocyte L-02-As via the activation of Akt pathway.

High concentrations of HgS, MeHg and toxic gas emissions in thermally affected waste dumps from hard coal mining in Poland

This study aims to provide numerous environmental research approaches to understand the formation of mineral and organic mercury compounds in self-heating coal waste dumps of the Upper Silesian Coal Basin (USCB). The results are combined with environmental and health risk assessments. The mineralogy comprised accessory minerals in the fine fraction of thermally affected waste, i.e., Hg sulfides, most likely cinnabar or metacinnabar. Moreover, other metals, e.g., Pb, Zn and Cu, were found as sulfide forms. Apart from Hg, the ICP-ES/MS data confirmed the high content of Mn, Zn, Pb, Hg, Cr and Ba in these wastes. The high concentration of available Hg resulted in elevated MeHg concentrations in the dumps. There were no correlations or trends between MeHg concentrations and elemental Hg, TS, TOC, and pH. Furthermore, we did not detect microbial genes responsible for Hg methylation. The organic compounds identified in waste and emitted gases, such as organic acids, or free methyl radicals, common in such burn environments, could be responsible for the formation of MeHg. The concentration levels of gases, e.g., benzene, formaldehyde, NH₃, emitted by the vents, reached or surpassed acceptable levels numerous times. The potential ecological and human health risks of these dumps were moderate to very high due to the significant influence of the high Hg concentrations.

Hexavalent chromium induces hepatocyte apoptosis via regulation of apoptosis signal-regulating kinase 1/c-Jun amino-terminal kinase signaling

With the spread of hexavalent chromium (Cr(VI)) contamination, Cr(VI)-induced hepatotoxicity has attracted increasing attention in recent years. To date, however, the exact mechanism of Cr(VI) toxicity remains unclear. In this study, we investigated the role of apoptosis signal-regulating kinase 1 (ASK1)/c-Jun amino-terminal kinase (JNK) in Cr(VI)-induced hepatic toxicity and the possible related mechanisms. AML-12 hepatocyte cell-lines were treated with 0, 1, 4, and 16 μmol/Lof Cr(VI) with or without GS-444271 (an ASK1 inhibitor). Adult male mice were administered with 0, 2, 8, and 32 mg/kg body mass (BM)/day of Cr(VI) for 5 days. The level of hepatocyte apoptosis/proliferation, generation of reactive oxygen species (ROS), and expression levels of mRNAs and proteins related to ASK1/JNK and nuclear factor-E2-related factor 2 (Nrf2) signaling were assessed. Results showed that high Cr(VI) exposure induced hepatocyte apoptosis and liver injury by generation of ROS and down-regulation of Nrf2 signaling. In addition, ASK1/JNK signaling activity was upregulated in the Cr(VI)-treated group. Furthermore, GS-444217 treatment significantly rescued Cr(VI)-induced hepatocyte apoptosis and liver dysfunction in vitro and in vivo by down-regulation of ASK1/JNK signaling. Thus, ASK1/JNK signaling appears to play an important role in Cr(VI)-induced hepatocyte apoptosis and liver injury. This study should help improve our understanding of the mechanism of Cr(VI)-induced liver injury and provide support for future investigations on liver disease therapy.

The Influence of Heavy Metals on Gastric Tumorigenesis

Objectives

This study aimed to observe the relationship among heavy metals concentration, microsatellite instability (MSI), and human epidermal growth factor receptor type 2 (HER2) gene amplification in gastric cancer (GC) patients.

Methods

The concentrations of 18 heavy metals in the plasma of GC patients and healthy controls were measured by inductive coupled plasma emission spectrometry (ICP-MS). MSI detection was conducted by detecting 5 microsatellite repeat markers by PCR analysis. HER2 gene amplification was detected by fluorescence in situ hybridization (FISH). The relationship among heavy metal elements, tumor biomarkers, HER2 amplification, and MSI status was analyzed by Pearson correlation analysis.

Results

A total of 105 GC patients and 62 healthy controls were recruited in this study. The concentration of arsenic (As), chromium (Cr), cuprum (Cu), mercury (Hg), manganese (Mn), lead (Pb), stibium (Sb), selenium (Se), stannum (Sn), strontium (Sr), thallium (Tl), vanadium (V), and zinc (Zn) were significantly different between GC patients and controls. Among 105 GC patients, including 87 microsatellite-stable (MSS) samples and 18 MSI samples, the concentration of Ga is significantly higher in the MSI group than that in the MSS group. Meanwhile, in 97 GC patients having detected HER2 gene amplification, 69 of 97 had negative HER2 gene amplification and the rest 28 GC patients had positive HER2 gene amplification. The concentration of Hg, Sn, and Tl is noticeably higher in the HER2 positive group than in the HER2 negative group. Only Sb was positively correlated with MSI, but none of these heavy metals was correlated with HER2 gene amplification.

Conclusions

The results indicated that Sb has significant positive correlation with the MSI status, which suggests that Sb may cause MSI in GC. However, further research studies are required to elucidate the mechanisms in the near feature.

Potential Protective Effect of Spirulina Platensis on Sodium Arsenite Induced Cardiotoxicity in Male Rats

BACKGROUND

Sodium arsenite is a dangerous bio-accumulative poison affecting a large number of people as well as animals throughout the world. It is used clinically in the treatment of certain medical conditions, but due to its harmful damage to different tissues and mainly the cardiotoxicity, its medical application is limited.

AIM

This study was conducted to investigate the protective effects of spirulina on cardiotoxicity induced by sodium arsenite biochemically and histologically.

METHODS

30 young adult male albino rats were randomly equally divided into three groups 10 animals each. Group I (control), Group II Arsenic intoxicated (10 mg/kg/day/ 4 weeks), Group III spirulina protected animals (concomitant sodium arsenite 10 mg/kg/day/ 4 weeks and spirulina 200 mg/kg/day/ 4 weeks).

RESULTS

It was evident from the study that arsenic exposure exerted a significant increase in cardiac enzyme levels, serum creatine kinase MB (CKMB) and troponin. Concomitant treatment with spirulina is considerably recovered their serum levels. Histological alterations associated with arsenite treated animals are significantly decreased after using spirulina.

CONCLUSIONS

The results of the present study showed that use of spirulina could alleviate the toxic effects on the heart following exposure to arsenic toxicity.

Bimetallic Cd/Zr-UiO-66 material as a turn-on/off probe for As5+/Fe3+ in organic media

In this work, a series of bimetallic Cd/Zr-UiO-66 materials were successfully synthesized for fluorescence sensing toward traces of As⁵⁺ and Fe³⁺ via a one-pot method. Interestingly, the obtained bimetallic Cd/Zr-UiO-66 (1:9) can be served as turn-on probe for As⁵⁺ as well as turn-off probe for Fe³⁺. The LODs of Cd/Zr-UiO-66 (1:9) toward As⁵⁺ and Fe³⁺ were calculated to be 5.4 μM and 4.3 μM, respectively, indicating its effective sensing properties for As⁵⁺ and Fe³⁺ in methanol media. Moreover, even in the presence of other potentially interfering toxic metal ions such as As³⁺, Cd²⁺ and Pb²⁺, Cd/Zr-UiO-66 (1:9) still presented good anti-interference abilities. Additionally, the removal efficiency of Cd/Zr-UiO-66 (1:9) toward As⁵⁺ was higher than 70% when the initial As⁵⁺ was lower than 50 mg/L. The fluorescence quenching of Fe³⁺ were mainly due to the competitive absorption of excitation source and RET, while the ACE mechanism was mostly responsible for the enhancement of As⁵⁺. More importantly, this job might pave the way for future researches and applications on sensing As⁵⁺ and Fe³⁺.

CPT2 downregulation triggers stemness and oxaliplatin resistance in colorectal cancer via activating the ROS/Wnt/β-catenin-induced glycolytic metabolism

Carnitine palmitoyltransferase 2 (CPT2) has been demonstrated to act as a tumor promotor or suppressor in different types of cancers. However, little is known about the effect of CPT2 on colorectal cancer (CRC). In the present study, we analyzed CPT2 expression in CRC tissues and cells. CPT2 was overexpressed in CRC cell lines (SW480 and RKO), and its effects and molecular mechanism on the proliferation, glycolysis, stemness, and oxaliplatin sensitivity were investigated. The xenograft experiment was used to confirm the influence of CPT2 on CRC tumorigenesis in vivo. We found that CPT2 expression was significantly downregulated in CRC patients, and its lower expression was associated with the poor prognosis, large tumor size, advanced TNM stage, and poor histological grade differentiation of patients. Upregulation of CPT2 significantly inhibited the proliferation, glycolytic metabolism, cancer stem cell properties, and oxaliplatin resistance in CRC cells. Also, the increase of CPT2 inhibited tumorigenesis, stemness and glycolysis, while enhanced oxaliplatin sensitivity in mouse models. Mechanistically, CPT2 functioned via suppressing the activation of Wnt/β-catenin pathway through repressing ROS production. In conclusion, our results demonstrated that CPT2 was decreased in CRC, and CPT2 downregulation could trigger stemness and oxaliplatin resistance in CRC via activating the ROS/Wnt/β-catenin-induced glycolytic metabolism. This study indicates that CPT2 is a potential therapeutic target for CRC.

Environmental Exposure to Heavy Metals Contributes to Diseases Via Deregulated Wnt Signaling Pathways

Wnt signaling plays a critical role during embryogenesis and is responsible for regulating the homeostasis of the adult stem cells and cells fate via a multitude of signaling pathways and associated transcription factors, receptors, effectors, and inhibitors. For this review, published articles were searched from PubMed Central, Embase, Medline, and Google Scholar. The search terms were Wnt, canonical, noncanonical, signaling pathway, β-catenin, environment, and heavy metals. Published articles on Wnt signaling pathways and heavy metals as contributing factors for causing diseases via influencing Wnt signaling pathways were included. Wnt canonical or noncanonical signaling pathways are the key regulators of stem cell homeostasis that control many mechanisms. There is an adequate balance between β-catenin dependent and independent Wnt signaling pathways and remain highly conserved throughout different development stages. Environmental heavy metal exposure may cause either inhibition or overexpression of any component of Wnt signaling pathways such as Wnt protein, transcription factors, receptors, ligands, or transducers to impede normal cellular function via negatively affecting Wnt signaling pathways. Environmental exposure to heavy metals potentially contributes to diseases via deregulated Wnt signaling pathways. 

Chromium (VI) promotes EMT by regulating FLNA in BLCA

Hexavalent chromium (Cr (VI)), which is a recognized human carcinogen, is widely used in industrial production of raw materials. Evidence verifies that environmental contaminants in the urine can induce malignant transformation in the urinary bladder tract, and our data indicate that Cr (VI) could promote the proliferation and migration and inhibit the apoptosis of bladder cancer (BLCA) cells. However, the molecular mechanism remains ambiguous. We find that Filamin A (FLNA) is overexpressed in BLCA, and Cr (VI) promotes epithelial-to-mesenchymal transition by regulating FLNA in BLCA. Thus, inhibiting the expression of FLNA may be a prospective method for limiting the BLCA progression caused by Cr (VI) exposure.

Quinazolin-derived myeloperoxidase inhibitor suppresses influenza A virus-induced reactive oxygen species, pro-inflammatory mediators and improves cell survival

Superoxide radicals and other reactive oxygen species (ROS) are implicated in influenza A virus-induced inflammation. In this in vitro study, we evaluated the effects of TG6-44, a novel quinazolin-derived myeloperoxidase-specific ROS inhibitor, on influenza A virus (A/X31) infection using THP-1 lung monocytic cells and freshly isolated peripheral blood mononuclear cells (PBMC). TG6-44 significantly decreased A/X31-induced ROS and virus-induced inflammatory mediators in THP-1 cells (IL-6, IFN-γ, MCP-1, TNF-α, MIP-1β) and in human PBMC (IL-6, IL-8, TNF-α, MCP-1). Interestingly, TG6-44-treated THP-1 cells showed a decrease in percent cells expressing viral nucleoprotein, as well as a delay in translocation of viral nucleoprotein into the nucleus. Furthermore, in influenza A virus-infected cells, TG6-44 treatment led to suppression of virus-induced cell death as evidenced by decreased caspase-3 activation, decreased proportion of Annexin V⁺PI⁺ cells, and increased Bcl-2 phosphorylation. Taken together, our results demonstrate the anti-inflammatory and anti-infective effects of TG6-44.

Arsenic exposure in drinking water reduces Lgr5 and secretory cell marker gene expression in mouse intestines

Arsenic is a global health concern that causes toxicity through ingestion of contaminated water and food. In vitro studies suggest that arsenic reduces stem and progenitor cell differentiation. Thus, this study determined if arsenic disrupted intestinal stem cell (ISC) differentiation, thereby altering the number, location, and/or function of intestinal epithelial cells. Adult male C57BL/6 mice were exposed to 0 or 100 ppb sodium arsenite (AsIII) through drinking water for 5 weeks. Duodenal sections were collected to assess changes in morphology, proliferation, and cell types. qPCR analysis revealed a 40% reduction in Lgr5 transcripts, an ISC marker, in the arsenic-exposed mice, although there were no changes in the protein expression of Olfm4. Secretory cell-specific transcript markers of Paneth (Defa1), Goblet (Tff3), and secretory transit amplifying (Math1) cells were reduced by 51%, 44%, and 30% respectively, in the arsenic-exposed mice, indicating significant impacts on the Wnt-dependent differentiation pathway. Further, protein levels of phosphorylated β-catenin were reduced in the arsenic-exposed mice, which increased the expression of Wnt-dependent transcripts CD44 and c-myc. PCA analysis, followed by MANOVA and regression analyses, revealed significant changes and correlations between Lgr5 and the transit amplifying (TA) cell markers Math1 and Hes1, which are in the secretory cell pathway. Similar comparisons between Math1 and Defa1 show that terminal differentiation into Paneth cells is also reduced in the arsenic-exposed mice. The data suggests that ISCs are not lost following arsenic exposure, but rather, specific Wnt-dependent progenitor cell formation and terminal differentiation in the small intestine is reduced.

A novel peptide promotes human trophoblast proliferation and migration through PI3K/Akt/mTOR signaling pathway

Background

Preeclampsia (PE) is a complex pregnancy-related disease that endangers the safety of maternal and fetal. The purpose of this study is to reveal the pathogenesis of preeclampsia and discover new predictors from the perspective of peptidomics. The umbilical cord blood of PE and control group was analyzed by peptidomics. A peptide named Regulation of Proliferation Process in Preeclampsia (ROPPIP) was screened out to explore its role in the proliferation, migration and apoptosis of trophoblast cells in preeclampsia.

Methods

We compared and analyzed the umbilical cord blood of patients with PE and normal pregnant women using liquid chromatography-tandem mass spectrometry (LC-MS). hTR-8/Svneo cells cultured in vitro were divided into ROPPIP group and a disordered peptide group as control. Cell Counting Kit-8 (CCK-8) assay, flow cytometry, Transwell chamber assays and western blot analysis were performed to detect cell proliferation, invasion, migration and apoptosis, in addition to the expression of Matrix metalloproteinase-2 (MMP2), nuclear associated antigen Ki67, B-cell lymphoma-2 (Bcl2), Caspase 3, and β-actin protein.

Results

We identified 133 differential peptides. Of these, 51 were up-regulated while 82 were down-regulated. the polypeptide SFGVRMATASPTDGNV with low differential expression in the serum of PE patients was selected for the study, we named the polypeptide as Regulation of Proliferation Process in PE (ROPPIP). The experiment shows that ROPPIP can up-regulate the expression levels of MMP2, Ki67, and Bcl2 in HTR-8/Svneo cells, down-regulate the expression of caspase-3, promote the proliferation and migration of HTR-8/Svneo cells and inhibit the apoptosis induced by cisplatin, the activation of the phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway may be associated with the function of ROPPIP.

Conclusions

ROPPIP promotes HTR-8/Svneo cells migration and proliferation, and inhibits apoptosis, by regulating the activation of the PI3K/AKT/mTOR signaling pathway.

Toxic Mechanisms of Five Heavy Metals: Mercury, Lead, Chromium, Cadmium, and Arsenic

The industrial activities of the last century have caused massive increases in human exposure to heavy metals. Mercury, lead, chromium, cadmium, and arsenic have been the most common heavy metals that induced human poisonings. Here, we reviewed the mechanistic action of these heavy metals according to the available animal and human studies. Acute or chronic poisonings may occur following exposure through water, air, and food. Bioaccumulation of these heavy metals leads to a diversity of toxic effects on a variety of body tissues and organs. Heavy metals disrupt cellular events including growth, proliferation, differentiation, damage-repairing processes, and apoptosis. Comparison of the mechanisms of action reveals similar pathways for these metals to induce toxicity including ROS generation, weakening of the antioxidant defense, enzyme inactivation, and oxidative stress. On the other hand, some of them have selective binding to specific macromolecules. The interaction of lead with aminolevulinic acid dehydratase and ferrochelatase is within this context. Reactions of other heavy metals with certain proteins were discussed as well. Some toxic metals including chromium, cadmium, and arsenic cause genomic instability. Defects in DNA repair following the induction of oxidative stress and DNA damage by the three metals have been considered as the cause of their carcinogenicity. Even with the current knowledge of hazards of heavy metals, the incidence of poisoning remains considerable and requires preventive and effective treatment. The application of chelation therapy for the management of metal poisoning could be another aspect of heavy metals to be reviewed in the future.

Ethanol extract of Vitellaria paradoxa (Gaertn, F) leaves protects against sodium arsenite - induced toxicity in male wistar rats

The inadvertent exposure to arsenic has been associated with diverse diseases such as cancers. Vitellaria paradoxa is a medicinal plant with antidiabetic and antiproliferative properties. Here, we assessed the ameliorative role of Ethanol Leaf extract of Vitellaria paradoxa (ELVp) in Sodium Arsenite (SA) - induced toxicity in rats after oral treatment for two weeks as follows: Group 1 (Control, distilled water), Group 2 (Vitamin E, 100 mg/kg), Groups 3 and 4 (ELVp, 100 & 200 mg/kg respectively), Group 5 (SA, 2.5 mg/kg), Group 6 (SA + Vit E) and Group 7 (SA + ELVp (100 mg/kg) and Group 8 (SA + ELVp (200 mg/kg). The results indicated that SA significantly increased liver and kidney function markers and elevated platelet, white blood cell (WBC) count and malondialdehyde levels in rats. Additionally, SA decreased Red Blood Cell (RBC), Hemoglobin (HGB) and Hematocrit (HCT) levels in rats (p < 0.05). Sodium arsenite caused mild expression of BCL-2 protein> NF-Kb = p53 in the kidney of rats. However, ELVp ameliorated SA-induced toxicity in the liver and kidney of rats with respect to these markers. Overall, ELVp has hepatoprotective, nephroprotective and apoptotic properties against sodium arsenite-induced toxicity.

The restoration of Wnt/β-catenin signalling activity by a tuna backbone-derived peptide ameliorates hypoxia-induced cardiomyocyte injury

Myocardial infarction (MI) is a serious disease with high morbidity and mortality worldwide. Reducing myocardial reperfusion injury in MI patients remains a challenge. The generation of excessive reactive oxygen species (ROS) during reperfusion is known to be responsible for injury. A peptide from tuna backbone protein (APTBP) captured our attention due to its strong antioxidant activity. Here, we aimed to assess the function of APTBP in protecting against myocardial ischaemia-reperfusion (I/R) injury and to clarify the associated mechanism. Two in vitro models generated by hypoxia and cobalt chloride treatment were used to determine the effect of APTBP on cardiomyocytes under hypoxic stress. In vivo, a rat model of I/R was generated to evaluate APTBP functions. As a result, APTBP attenuated hypoxia- or cobalt chloride-induced injury to H9C2 cells and primary cardiomyocytes. Moreover, hypoxia-induced apoptosis, ROS generation and impaired mitochondrial function were also suppressed by APTBP administration. In vivo, tail vein injection of APTBP ameliorated pathological damage and mildly restored cardiac function. To clarify the mechanism, RNA-seq was performed and revealed that the Wnt signalling pathway may be associated with this mechanism. Rescue analysis showed that β-catenin knockdown diminished the protective effect of APTBP and that the expression of an ROS generator abolished the restoration of Wnt/β-catenin signalling induced by APTBP. Collectively, our findings suggest that APTBP reduces cardiomyocyte apoptosis and protects against myocardial ischaemia-reperfusion injury by scavenging ROS and subsequently restoring Wnt/β-catenin signalling.

Associated Effects and Efficiency Evaluation between Wastewater Pollution and Water Disease Based on the Dynamic Two-Stage DEA Model

The lack of basic water supply and treatment facilities during China's urbanization and industrialization process has resulted in a large amount of wastewater pollution, with the most serious water diseases being water-borne endemic fluorosis and arsenic poisoning, which have affected more than 20 million people. This research therefore uses the improved modified undesirable dynamic network model to analyze data of 31 provincial administrative regions to focus on the associated effects and efficiency evaluation between wastewater pollution and water disease in China. The results show that the efficiency of water pollution disease in all four regions of the country and the total efficiency in the east, west, and central regions all show a decreasing trend, while the efficiency scores and rankings of all provinces and cities within the region fluctuate greatly. The eastern region with the most developed economy has the best overall performance, with higher efficiency in water consumption and water disease control. However, the efficiency of wastewater treatment in northeast China is stable and better. Given the high level of the nation's economic development and the results of efficiency in water pollution and water diseases, improving the efficiency and quality of wastewater treatment in China is regarded as an important factor for achieving the strategic goal of green growth.

Effects of Arsenic on wnt/β-catenin Signaling Pathway: A Systematic Review and Meta-analysis

We aimed to systematically evaluate the regulatory effect of arsenic on wnt/β-catenin signaling pathway and to provide theoretical basis for revealing the mechanism of the relationship between arsenic and cell proliferation. The meta-analysis was carried out using Revman5.2 and Stata13.0 to describe the differences between groups with standard mean difference. We found in normal cells that the levels of wnt3a, β-catenin, glycogen synthase kinase-3β phosphorylated at serine 9 (p-GSK-3β(Ser9)), cyclinD1, proto-oncogene c-myc, and vascular endothelial growth factor (VEGF) in the arsenic intervention group were higher than those in the control group, and the level of glycogen synthase kinase-3β (GSK-3β) was lower than that in the control group (P < 0.05, respectively). Subgroup analysis showed that for a long time period (>24 h), the level of β-catenin in the arsenic intervention group was higher than that in the control group, and the level of GSK-3β of the same long-time period (>24 h) with low-dose (≤5 μM) intervention was lower than those in the control group (P < 0.05, respectively). In cancer cells, the levels of β-catenin, cyclinD1, c-myc, and VEGF in the arsenic intervention group were lower than those in the control group, while the level of GSK-3β in the arsenic intervention group was higher than that in the control group (P < 0.05, respectively). Subgroup analysis showed that the levels of β-catenin, cyclinD1, and c-myc in the high-dose (>5 μM) arsenic intervention group were lower than those in the control group, and the levels of β-catenin and cyclinD1 in the high-dose (>5 μM) arsenic intervention group were lower than those in the low-dose (≤5 μM) arsenic intervention group (P < 0.05, respectively). In addition, the regulation of arsenic on β-catenin was dose-dependent in the range of arsenic concentration from 0 to 7.5 μM. This study revealed that arsenic could upregulate wnt/β-catenin signaling pathway in normal cells and downregulate it in cancer cells, and its effect was affected by time and dose.

The acute toxic effects of hexavalent chromium on the liver of marine medaka (Oryzias melastigma)

Chromium is toxic to marine animals and can cause damage to many of their organs, including the liver. To test the toxicity of chromium on marine organisms, we exposed the liver of the marine medaka (Oryzias melastigma) with hexavalent chromium [Cr(VI)]. Our results show that Cr enrichment in the liver demonstrates a positive correlation to the exposure concentration. With the increase of Cr(VI) concentration, pathological changes including nuclear migration, cell vacuolization, blurred intercellular gap, nuclear condensation, become noticeable. To further study changes in gene expression in the liver after Cr(VI) exposure, we used RNA-seq to compare expression profiles before and after Cr(VI) exposure. After acute Cr(VI) exposure (2.61 mg/l) for 96 h, 5862 transcripts significantly changed. It is the first time that the PPAR pathway was found to respond sensitively to Cr(VI) exposure in fish. Finally, combined with other published study, we found that there may be some difference between Cr(VI) toxicity in seawater fish and freshwater fish, due to degree of oxidative stress, distribution patterns and detailed Cr(VI) toxicological mechanisms. Not only does our study explore the mechanisms of Cr(VI) toxicity on the livers of marine medaka, it also points out different Cr(VI) toxicity levels and potential mechanisms between seawater fish and freshwater fish.

DNA methylome and transcriptome alterations and cancer prevention by triterpenoid ursolic acid in UVB-induced skin tumor in mice

Nonmelanoma skin cancers (NMSCs) are the most common type of skin cancers. Major risk factors for NMSCs include exposure to ultraviolet (UV) irradiation. Ursolic acid (UA) is a natural triterpenoid enriched in blueberries and herbal medicinal products, and possess anticancer activities. This study focuses on the impact of UA on epigenomic, genomic mechanisms and prevention of UVB-mediated NMSC. CpG methylome and RNA transcriptome alterations of early, promotion and late stages of UA treated on UVB-induced NMSC in SKH-1 hairless mice were conducted using CpG methyl-seq and RNA-seq. Samples were collected at weeks 2, 15, and 25, and integrated bioinformatic analyses were performed to identify key pathways and genes modified by UA against UVB-induced NMSC. Morphologically, UA significantly reduced NMSC tumor volume and tumor number. DNA methylome showed inflammatory pathways IL-8, NF-κB, and Nrf2 pathways were highly involved. Antioxidative stress master regulator Nrf2, cyclin D1, DNA damage, and anti-inflammatory pathways were induced by UA. Nrf2, cyclin D1, TNFrsf1b, and Mybl1 at early (2 weeks) and late (25 weeks) stages were identified and validated by quantitative polymerase chain reaction. In summary, integration of CpG methylome and RNA transcriptome studies show UA alters antioxidative, anti-inflammatory, and anticancer pathways in UVB-induced NMSC carcinogenesis. Particularly, UA appears to drive Nrf2 and its upstream/downstream genes, anti-inflammatory (at early stages) and cell cycle regulatory (both early and late stages) genes, of which might contribute to the overall chemopreventive effects of UVB-induced MNSC. This study may provide potential biomarkers/targets for chemoprevention of early stage of UVB-induced NMSC in human.

Emerging Perspective: Role of Increased ROS and Redox Imbalance in Skin Carcinogenesis

Strategies to battle malignant tumors have always been a dynamic research endeavour. Although various vehicles (e.g., chemotherapeutic therapy, radiotherapy, surgical resection, etc.) are used for skin cancer management, they mostly remain unsatisfactory due to the complex mechanism of carcinogenesis. Increasing evidence indicates that redox imbalance and aberrant reactive oxygen species (ROS) are closely implicated in the oncogenesis of skin cancer. When ROS production goes beyond their clearance, excessive or accumulated ROS could disrupt redox balance, induce oxidative stress, and activate the altered ROS signals. These would damage cellular DNA, proteins, and lipids, further leading to gene mutation, cell hyperproliferation, and fatal lesions in cells that contribute to carcinogenesis in the skin. It has been known that ROS-mediated skin carcinogenesis involves multiple ways, including modulating related signaling pathways, changing cell metabolism, and causing the instability of the genome and epigenome. Nevertheless, the exact role of ROS in skin cancer has not been thoroughly elucidated. In spite of ROS inducing skin carcinogenesis, toxic-dose ROS could trigger cell death/apoptosis and, therefore, may be an efficient therapeutic tool to battle skin cancer. Considering the dual role of ROS in the carcinogenesis and treatment of skin cancer, it would be essential to clarify the relationship between ROS and skin cancer. Thus, in this review, we get the related data together to seek the connection between ROS and skin carcinogenesis. Besides, strategies basing on ROS to fight skin cancer are discussed.

Silencing GSK3β instead of DKK1 can inhibit osteogenic differentiation caused by co-exposure to fluoride and arsenic

Chronic exposure to combined fluoride (F) and arsenic (As) continues to be a major public health problem worldwide, attracting the attention of an increasing number of researchers. While bone is the main target organ of syndrome of endemic arsenic poisoning and fluorosis (SEAF), the specific mechanism and targeted intervention remains uncertain. The first question in this study sought to determine the interaction of F and As on the Wnt signaling pathway and its role in osteogenic differentiation in the SEAF population. As can be seen from the data, with the increase in exposure to F, the content of Wnt signaling inhibitor Dickkopf-related protein 1 (DKK1) gradually decreased, but the expression of glycogen synthase kinase-3β (GSK3β), β-catenin and the osteogenic differentiation indicators pro-collagen I alpha 1 (COL1A1) and bone alkaline phosphatase (BALP) were increased. Next, we grouped the SEAF population according to urinary As and found that As can upregulate the GSK3β, β-catenin level and the bone formation bio-marker BALP in serum. But the experiments did not detect any evidence that As can change the content of DKK1 in serum. To better understand the combined effects of F and As on the Wnt signaling pathway, we performed further interaction analysis. These results suggest that the interaction of F and As can inhibit the GSK3β, β-catenin, COL1A1 and BALP. And DKK1 is mainly manifested by the independent effect of F. To further study the role of DKK1 and GSK3β in fluoride-arsenic pollution combined with osteogenic differentiation, we attempted to silence the DKK1 and GSK3β gene in hFOB 1.19 cells. The results show that F, As alone and in combination exposure can up-regulate GSK catenin transcription and protein expression levels and down-regulate DKK1, and COL1A1 and ALP are significantly increased, after silenced the DKK1. The same results did not appear after silenced the GSK3β. F and As alone and in combination exposure did not reverse the inhibition of GSK3β and β-catenin by GSK3β silencing, and COL1A1 and ALP are significantly decreased. The results indicate that silencing GSK3β instead of DKK1 can inhibit osteogenic differentiation caused by co-exposure to fluoride and arsenic. This study can provide a scientific basis for further understanding the causes of bone formation caused by F and As and the improvement of targeted intervention strategies.

The crosstalk between trace elements with DNA damage response, repair, and oxidative stress in cancer

DNA damage response (DDR) is a regulatory system responsible for maintaining genome integrity and stability, which can sense and transduce DNA damage signals. The severity of damage appears to determine DDRs, which can include damage repair, cell-cycle arrest, and apoptosis. Furthermore, defective components in DNA damage and repair machinery are an underlying cause for the development and progression of various types of cancers. Increasing evidence indicates that there is an association between trace elements and DDR/repair mechanisms. In fact, trace elements seem to affect mediators of DDR. Besides, it has been revealed that oxidative stress (OS) and trace elements are associated with cancer development. In this review, we discuss the role of some critical trace elements in the risk of cancer. In addition, we provide a brief introduction on DDR and OS in cancer. Finally, we will further review the interactions between some important trace elements including selenium, zinc, chromium, cadmium, and arsenic, and DDR, and OS in cancer.

Metformin inhibited colitis and colitis-associated cancer (CAC) through protecting mitochondrial structures of colorectal epithelial cells in mice

Although a mountain of papers have showed that metformin plays a role in inhibiting cancers, but the mechanism underpinning this has not yet fully elucidated. Herein, we used AOM/DSS model, the clinicopathological features are similar to those found in humans, to investigate the effects of metformin as well as combination with 5-FU in the prevention of colitis and colitis associated cancer (CAC). Oral metformin significantly inhibited DSS-induced ulcerative colitis and AOM/DSS-induced CAC. Metformin also ameliorated 5-FU-induced colorectal gastrointestinal symptoms in mice. Metformin combination with 5-FU strongly inhibited colorectal cancer. Metformin reduced levels of the NFκB signaling components p-IKKα/β, p-NFκB, p-IκBα in colorectal mucosal cells. Transmission electron microscopy analysis suggested that the inhibition of metformin on colitis and CAC might associate with its biological activity of protecting mitochondrial structures of colorectal epithelial cells. Further analysis by Mito Tracker Red staining assay indicated that metformin prevented H₂O₂-induced mitochondrial fission correlated with a decrease of mitochondrial perimeter. In addition, metformin increased the level of NDUFA9, a Q-module subunit required for complex I assembly, in colorectal epithelial cells. These observations of metformin in the inhibition of colitis and CAC might associate with its activity of activating the LKB1/AMPK pathway in colorectal epithelial cells. In conclusion, metformin inhibited colitis and CAC through protecting the mitochondrial structures of colorectal epithelial cells.

Tumor Necrosis Factor Ligand-Related Molecule 1A Regulates the Occurrence of Colitis-Associated Colorectal Cancer

BACKGROUND

Tumor necrosis factor ligand-related molecule 1 A (TLlA) is closely related to the occurrence and development of inflammatory bowel disease.

AIMS

We aimed to explore whether TLlA was involved in the occurrence of colitis-associated colorectal cancer (CAC).

METHODS

Firstly, azoxymethane (AOM) and dextran sulfate sodium (DSS) were used to construct the CAC mice model in wild-type (WT) and TL1A transgenic (Tg) mice with TL1A high expression. The histopathological analysis was used for the evaluation of inflammation level, and the immunohistochemistry staining analysis was used to test the expression and location of proliferating cell nuclear antigen (PCNA) and β-catenin. Secondly, the HCT116 and HT29 cell lines were used for knockdown of TL1A gene for further assay including cell viability, cell clone, cell apoptosis and matrigel invasion. Western blot were used for quantitative protein expression of β-catenin and downstream oncogenes including c-myc and Cyclin D1 after knockdown of TL1A gene.

RESULTS

The evaluation of inflammation level showed that the disease activity index score and tumor formation rate were significantly higher in AOM + DSS/Tg group than that in AOM + DSS/WT group. The expression of PCNA, β-catenin, c-myc, and Cyclin D1 in AOM + DSS/Tg group was significantly higher than that in AOM + DSS/WT group. The cell experiment showed that TL1A knockdown inhibited the cell proliferation, invasion, and migration. Moreover, the expression of c-myc and Cyclin D1 was significantly decreased after TL1A knockdown.

CONCLUSIONS

TL1A can induce tumor cell proliferation and promote the occurrence of CAC by activating Wnt/β-catenin pathway.

Exposure to Arsenite in CD-1 Mice during Juvenile and Adult Stages: Effects on Intestinal Microbiota and Gut-Associated Immune Status

Intestinal microbiota composition and gut-associated immune response can contribute to the toxicity of arsenic. We investigated the potential toxicity of short-term arsenic exposure on gut microbiome composition, intestinal immune status, microbial arsenic resistance gene, and arsenic metabolic profiles in adult and developmental stages of CD-1 mice. The potential toxicity of arsenite [As(III)] was determined for two life stages: (i) adult animals at 24 or 48 h after single gavage (0.05 mg/kg body weight [b.w.] [low dose], 0.1 mg/kg b.w. [medium dose], and 0.2 mg/kg b.w. [high dose]) and repeated exposure at 1 mg/liter for 8 days and (ii) postnatal day 10 (PND10) and PND21 after single gavage (0.05 mg/kg b.w.). Dose- and time-dependent responses in bacterial recovery/microbial composition were observed in adults after a single gavage. Repeated exposure caused a transient decrease in the recovery of intestinal bacteria, a shift in the bacterial population with abundance of arsenic resistance genes, and evidence for host metabolism of arsenite into less-reactive trivalent methylated species. Arsenic exposure in adult animals induced high levels of CC chemokines and of proinflammatory and anti-inflammatory cytokine secretion in intestine. Arsenic exposure at PND21 resulted in the development of distinct bacterial populations. Results of this study highlight significant changes in the intestinal microbiome and gut-associated immune status during a single or repeated exposure to arsenic in juvenile and adult animals. The data warrant investigation of the long-term effects of oral arsenic exposure on the microbiome and of immune system development and responses.IMPORTANCE Transformation of organic arsenic to toxic inorganic arsenic (iAs) is likely carried out by intestinal bacteria, and iAs may alter the viability of certain microbial populations. This study addressed the impact of arsenic exposure on intestinal microbiota diversity and host gut-associated immune mediators during early development or adulthood using scenarios of acute or repeated doses. During acute arsenic exposure, animals developed defense functions characterized by higher abundances of bacteria that are involved in arsenic resistance or detoxification mechanisms. Arsenite had a negative effect on the abundance of bacterial species that are involved in the conversion of protein to butyrate, which is an alternative energy source in the intestine. The intestinal mucosal immune cytokine profile reflected a mechanism of protection from arsenic toxicity.

An in vivo analysis of Cr6+ induced biochemical, genotoxicological and transcriptional profiling of genes related to oxidative stress, DNA damage and apoptosis in liver of fish, Channa punctatus (Bloch, 1793)

Present study was designed to assess the hexavalent chromium (Cr⁶⁺) mediated oxidative stress that induces DNA damage and apoptosis in adult fish, Channa punctatus (35 ± 3.0 g; 14.5 ± 1.0 cm; Actinopterygii). Fishes were maintained in three groups for 15, 30 and 45 d of exposure periods. They were treated with 5% (Group T1) and 10% (Group T2) of 96 h-LC₅₀ of chromium trioxide (Cr⁶⁺). Controls were run for the similar duration. A significant (p < 0.05) increment in the activities of antioxidant enzymes, SOD and CAT in liver tissues of the exposed fish evinces the persistence of oxidative stress. A significant (p < 0.05) increase in induction of micronuclei (MN) coupled with transcriptional responses of target genes related to antioxidant enzymes, DNA damage and apoptosis (sod, cat, gsr, nox-1, p53, bax, bcl-2, apaf-1 and casp3a) establishes the impact of oxidative stress due to in vivo, Cr⁶⁺ accumulation in liver as compared to control (0 mg/L), in a dose and exposure-dependent manner. Initially, the increased level of reactive oxygen species (ROS) in liver coincided with that of enhanced mRNA expression of antioxidant enzymes, sod, cat, gsr and nox-1 but, later, the overproduction of ROS, after 45 d of exposure of Cr⁶⁺, resulted in a significant (p < 0.05) up-regulation of p53. Our findings also unveil that the up-regulation of bax, apaf-1 and casp3a and down-regulation of bcl-2 are associated with Cr⁶⁺-induced oxidative stress mediated-apoptosis in liver of test fish. Aforesaid molecular markers can, thus, be efficiently utilized for bio-monitoring of aquatic regimes and conservation of fish biodiversity.

A comparative study on subacute toxicity of arsenic trioxide and dimethylarsinic acid on antioxidant status in Crandell Rees feline kidney (CRFK), human hepatocellular carcinoma (PLC/PRF/5), and epithelioma papulosum cyprini (EPC) cell lines

Arsenic (As) is a global contaminant of terrestrial and aquatic environments posing concern for environmental and human health. The effects of subacute concentrations of arsenic trioxide (As^III) and dimethylarsinic acid (DMA^V) were examined using Crandell Rees feline kidney (CRFK), human hepatocellular carcinoma (PLC/PRF/5), and epithelioma papulosum cyprini (EPC). Whole monolayer with suffering cells (confluence 100%, pyknosis and refractive cells; value scale = 2) led to identification of subacute As concentrations for the three cell lines. The selected As^III concentrations were 1.33 µM for CRFK and 33.37 µM for PLC/PRF/5 and EPC, at 48 hr time point. The selected DMA^V concentrations were 0.67 mM for PLC/PRF/5, 1.33 mM for CRFK, and 2.67 mM for EPC for 48 hr. Unlike the As^III test, the three cell lines did not exhibit marked susceptibility to DMA^V-mediated toxicity. Several oxidative stress biomarker levels, directly or indirectly associated with reactive oxygen species (ROS) elimination including superoxide dismutase, catalase, glutathione peroxidases, glutathione reductase, glutathione S-transferase, glyoxalase I, glyoxalase II, and total glutathione, were determined in the three cell lines at 24 and 48 hr. Antioxidant responses in metal-treated cells were significantly altered compared to controls, suggesting a perturbation of redox state. The weakening of antioxidant pathway in either healthy or tumoral cells was greater using As^III than DMA^V. Differences in level of several oxidative stress biomarkers suggest that the oxidative stress mechanism induced by As^III is distinctly different from DMA^V. Multifaceted mechanisms of action underlying ROS generation in tumor and nontumor cells versus As^III and DMA^V exposure are thus involved. Since As-mediated toxicity is quite complex, more data regarding both oxidant-enhancement and oxidant-lowering strategies may be useful to improve knowledge regarding the influence of As on human and animal cells.

Arsenic trioxide exposure accelerates colon preneoplasic aberrant crypt foci induction regionally through mitochondrial dysfunction

Arsenic poisoning is a worldwide problem. Thus, we studied the effects of arsenic trioxide (ATO) administration on a 1,2-dimethylhydrazine (DMH)-induced preneoplasic colon carcinogenesis model. Mice were separated into four study groups; the control group received only vehicles. The ATO group received daily a 2.5 mg kg^-1 dose for 4 weeks. The DMH group received DMH (20 mg kg^-1) twice in two weeks. The third group (D-ATO) had the same as the DMH group with ATO administration starting at week 10. At the end of 14 weeks, colons from sacrificed mice were taken, segmented into distal and proximal and subjected to aberrant crypt foci (ACF), aberrant crypt (AC) counting, alcian blue, H&E and Hoechst histological study and lastly oxidative stress marker analysis as well as mitochondrial swelling assessment. Data showed a significant increase in ACF and AC after DMH treatment, which was further increased after ATO addition. A perturbed histological structure was observed and loss of mucin producing cells in the colon tissue was observed. An important impact on the distal colon compared to the proximal one was noticed. The oxidative stress balance showed a similar pattern with an increase in MPO, NO/l-ornithine balance and MDA, while a decrease was observed in the antioxidant enzymes (CAT, SOD and GSH). In all parameters analyzed, the distal colons showed higher values than proximal. Furthermore, histological cell death analysis in combination with mitochondrial permeability pore opening suggested ATO contribution in the pathological effect. Our study has shown that ATO administration accelerated colon cancer development suggesting the heaviness of such treatments and the need to explore combinations and cycle type formulas.

Antioxidants Protect against Arsenic Induced Mitochondrial Cardio-Toxicity

Arsenic is a potent cardiovascular toxicant associated with numerous biomarkers of cardiovascular diseases in exposed human populations. Arsenic is also a carcinogen, yet arsenic trioxide is used as a therapeutic agent in the treatment of acute promyelotic leukemia (APL). The therapeutic use of arsenic is limited due to its severe cardiovascular side effects. Many of the toxic effects of arsenic are mediated by mitochondrial dysfunction and related to arsenic's effect on oxidative stress. Therefore, we investigated the effectiveness of antioxidants against arsenic induced cardiovascular dysfunction. A growing body of evidence suggests that antioxidant phytonutrients may ameliorate the toxic effects of arsenic on mitochondria by scavenging free radicals. This review identifies 21 antioxidants that can effectively reverse mitochondrial dysfunction and oxidative stress in cardiovascular cells and tissues. In addition, we propose that antioxidants have the potential to improve the cardiovascular health of millions of people chronically exposed to elevated arsenic concentrations through contaminated water supplies or used to treat certain types of leukemias. Importantly, we identify conceptual gaps in research and development of new mito-protective antioxidants and suggest avenues for future research to improve bioavailability of antioxidants and distribution to target tissues in order reduce arsenic-induced cardiovascular toxicity in a real-world context.

Electrozymographic evaluation of the attenuation of arsenic induced degradation of hepatic SOD, catalase in an in vitro assay system by pectic polysaccharides of Momordica charantia in combination with curcumin

Momordica charantia (MC) fruit known as bitter gourd, is of potential nutritional and medicinal value. The objectives of the present in vitro study were to evaluate the efficacy of bioactive pectic polysaccharides (CCPS) of MC along with another well-known bioactive compound curcumin in the abrogation of hepatocellular oxidative stress persuaded by sodium arsenite. Electrozymographic method was developed for the assessment of superoxide dismutase (SOD) and catalase activities of liver tissues maintained under an in vitro system. A significant association of CCPS of MC in combination with curcumin was found in the alleviation of oxidative stress induced by sodium arsenite in liver slice. Generated data pointed out that CCPS of MC and curcumin separately or in combination can offer significant protection against alterations in malondialdehyde (MDA), conjugated diene (CD) and antioxidative defense (SOD, CAT) markers. Furthermore, results of hepatic cell DNA degradation strongly supported that both these co-administrations have efficacy in preventing cellular damage. This is the first information of extracted polysaccharides from MC preventing arsenic induced damage in a liver slice of rat.

Downregulation of NEDD9 by apigenin suppresses migration, invasion, and metastasis of colorectal cancer cells

Apigenin is a natural flavonoid which possesses multiple anti-cancer properties such as anti-proliferation, anti-inflammation, and anti-metastasis in many types of cancers including colorectal cancer. Neural precursor cell expressed developmentally downregulated 9 (NEDD9) is a multi-domain scaffolding protein of the Cas family which has been shown to correlate with cancer metastasis and progression. The present study investigates the role of NEDD9 in apigenin-inhibited cell migration, invasion, and metastasis of colorectal adenocarcinoma DLD1 and SW480 cells. The results show that knockdown of NEDD9 inhibited cell migration, invasion, and metastasis and that overexpression of NEDD9 promoted cell migration and invasion of DLD1 cells and SW4890 cells. Apigenin treatment attenuated NEDD9 expression at protein level, resulting in reduced phosphorylations of FAK, Src, and Akt, leading to inhibition on cell migration, invasion, and metastasis of both DLD1 and SW480 cells. The present study has demonstrated that apigenin inhibits cell migration, invasion, and metastasis through NEDD9/Src/Akt cascade in colorectal cancer cells. NEDD9 may function as a biomarker for evaluation of cancer aggressiveness and for selection of therapeutic drugs against cancer progression.

Different roles of ROS and Nrf2 in Cr(VI)-induced inflammatory responses in normal and Cr(VI)-transformed cells

Hexavalent chromium (Cr(VI)) is classified as a human carcinogen. Cr(VI) has been associated with adenocarcinomas and squamous cell carcinoma of the lung. The present study shows that acute Cr(VI) treatment in human bronchial epithelial cells (BEAS-2B) increased inflammatory responses (TNF-α, COX-2, and NF-кB/p65) and expression of Nrf2. Cr(VI)-induced generation of reactive oxygen species (ROS) are responsible for increased inflammation. Despite the fact that Nrf2 is a master regulator of response to oxidative stress, silencing of Nrf2 in the acute Cr(VI) treatment had no effect on Cr(VI)-induced inflammation. In contrast, in Cr(VI)-transformed (CrT) cells, Nrf2 is constitutively activated. Knock-down of this protein resulted in decreased inflammation, while silencing of SOD2 and CAT had no effect in the expression of these inflammatory proteins. Results obtained from the knock-down of Nrf2 in CrT cells are very different from the results obtained in the acute Cr(VI) treatment. In BEAS-2B cells, knock-down of Nrf2 had no effect in the inflammation levels, while in CrT cells a decrease in the expression of inflammation markers was observed. These results indicate that before transformation, ROS plays a critical role while Nrf2 not in Cr(VI)-induced inflammation, whereas after transformation (CrT cells), Nrf2 is constitutively activated and this protein maintains inflammation while ROS not. Constitutively high levels of Nrf2 in CrT binds to the promoter regions of COX-2 and TNF-α, leading to increased inflammation. Collectively, our results demonstrate that before cell transformation ROS are important in Cr(VI)-induced inflammation and after transformation a constitutively high level of Nrf2 is important.

Ellagic acid protects against arsenic toxicity in isolated rat mitochondria possibly through the maintaining of complex II

Chronic arsenic exposure has been linked to many health problems including diabetes and cancer. In the present study, we assessed the protective effect of ellagic acid (EA) against toxicity induced by arsenic in isolated rat liver mitochondria. Reactive oxygen species (ROS) and mitochondrial membrane potential decline were assayed using dichlorofluorescein diacetate and rhodamine 123, respectively, and dehydrogenase activity obtained by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide conversion assay. Arsenic increased ROS levels and mitochondrial dysfunction, which led to a reduction in mitochondrial total dehydrogenase activity. Mitochondria pretreated with EA exposed to arsenic at various concentrations led to a reversal of ROS production and mitochondrial damage. Our results showed that mitochondria were significantly affected when exposed to arsenic, which resulted in excessive ROS production and mitochondrial membrane disruption. Pretreatment with EA, reduced ROS amounts, mitochondrial damage, and restored total dehydrogenase activity specifically associated with mitochondrial complex II. EA protective characteristics may be accomplished particularly throughout the mitochondrial maintenance either directly by its antioxidant property or indirectly through its maintaining of complex II. These findings also suggest a potential role for EA in treating or preventing mitochondria associated disorders.

Effects of glutathione on the in vivo metabolism and oxidative stress of arsenic in mice

In this study, we investigated the in vivo effects of exogenous glutathione and buthionine sulfoximine on arsenic methylation and antioxidant capacity in mice exposed to arsenic via drinking water. Thirty-six female albino mice were randomly divided into six groups. All groups were given free access to drinking water that contained arsenic continuously except the control group. After ten days, mice were treated with different levels of glutathione or buthionine sulfoximine. The levels of the metabolites of arsenic were determined in the liver and urine. The levels of glutathione and total antioxidant capacity were determined in the whole blood and liver. Our results showed that the increase of arsenic species in the liver as well as the decrease of blood and hepatic glutathione and total antioxidant capacity, were all relieved by exogenous glutathione consistently. We also observed the involvement of glutathione in promoting arsenic methylation and urinary elimination in vivo. Increase of total arsenic in the urine was mainly due to the increase of dimethylated arsenic. Furthermore, administration of glutathione increased the first methylation ratio and secondary methylation ratio in the liver and urine, which resulted in the consequent increase of dimethylated arsenic percent and decrease of inorganic arsenic percent in the urine. Opposite effects appeared with the administration of buthionine sulfoximine, a scavenger of glutathione. Our study indicated that exogenous glutathione not only accelerated the methylation and the excretion of arsenic, but also relieve the arsenic-induced oxidative stress. This provides a potential useful chemopreventive dietary component for human populations being at risk of arsenic exposure.

Therapeutic effect of hydroxychloroquine on colorectal carcinogenesis in experimental murine colitis

Chronic inflammation in the intestine is a strong risk factor for colitis-associated colorectal cancer (CAC). Hydroxychloroquine (HCQ) is widely used as an anti-inflammatory drug in the treatment of immune-mediated inflammatory disorders and various tumors. However, little is known regarding the effects of HCQ on colitis-associated tumorigenesis. In this study, mice treated with HCQ showed a significant reduction in early-stage colitis following azoxymethane (AOM)/dextran sodium sulfate (DSS) administration, as well as a remarkable inhibition of colonic tumorigenesis and tumor growth at late stages of CAC. Mechanistically, the therapeutic effects of HCQ were attributed to inhibition of inflammatory responses and production of mutagenic reactive oxygen species (ROS) in immune cells and subsequent promotion of apoptosis and cell cycle arrest in tumor cells. Furthermore, we found that HCQ inhibited the production of inflammatory cytokines and ROS in response to toll-like receptor 4 (TLR4) activation in macrophages. Our data presented herein may help guide the clinical use of HCQ as a prevention and treatment strategy for CAC.

Progress and prospects of reactive oxygen species in metal carcinogenesis

Carcinogenesis induced by environmental metal exposure is a major public health concern. The exact mechanisms underlying metal carcinogenesis remain elusive. In the past few decades, the relationship between metal induced generation of reactive oxygen species (ROS) and the mechanism of metal carcinogenesis has been established. The carcinogenic process is a very complex one. In the early stage of metal carcinogenesis or cell transformation high levels of ROS are oncogenic by causing DNA damage, genetic instability, epigenetic alteration, and metabolic reprogramming, leading to malignant transformation. In the second stage of metal carcinogenesis or the cancer development of metal-transformed cells, low levels of ROS are carcinogenic by promoting apoptosis resistance. The metal-transformed cells have the property of autophagy deficiency, resulting in accumulation of p62 and constitutive activation of Nrf2, and leading to higher levels of antioxidants, decreased levels of ROS, apoptosis resistance, inflammation, and angiogenesis. This review summarizes the most recent development in the field of metal carcinogenesis with emphasis on the difference in cellular events between early (cell transformation) and late (after cell transformation) stages of metal carcinogenesis.

Influence of diet, vitamin, tea, trace elements and exogenous antioxidants on arsenic metabolism and toxicity

Health risk of arsenic (As) has received increasing attention. Acute and chronic exposure to As could cause several detrimental effects on human health. As toxicity is closely related to its bioaccessibility and metabolism. In real environment, many factors, such as diet and nutrition, can influence As bioaccessibility, metabolism and toxicity. This paper mainly reviews the influences of diets and elements on As bioaccessibility, metabolism and toxicity and their underlying mechanisms to provide suggestions for future investigations. Vitamins, jaggery, fruit, tea, glutathione, N-acetylcysteine and zinc could reduce the As-induced toxicity by increasing antioxidative enzymes to antagonize oxidative stress caused by As and/or increasing As methylation. However, bean and betel nut could increase risk of skin lesions caused by As. Interestingly, high-fat diet, selenium and iron have incompatible effects on As bioaccessibility, metabolism and toxicity in different experimental conditions. Based on current literatures, the As methylation and As-induced oxidative damage might be two main ways that the diets and elements influence As toxicity. Combined application of in vitro human cell lines and gastrointestinal models might be useful tools to simultaneously characterize the changes in As bioaccessibility and toxicity in the future research.

Oxidative stress, epigenetics, and cancer stem cells in arsenic carcinogenesis and prevention

The carcinogenic role of arsenic has been extensively studied for more than half century. How arsenic causes human cancer, however, remains to be fully elucidated. In this brief review, we focus our attentions on the most recent discoveries by us and others on the capabilities of arsenic in inducing generation of reactive oxygen species (ROS), expression of microRNAs (miRNAs) and the generation of the cancer stem cells. We believe that these new understandings on the mechanisms of arsenic-induced carcinogenesis will shed light on the prevention and treatment of human cancers resulted from environmental or occupational arsenic exposure. Furthermore, these latest findings on arsenic-induced cellular responses will also have an important impact on the investigation of the carcinogenic effects of other environmental or occupational carcinogens or hazards.

Reactive Oxygen Species and Targeted Therapy for Pancreatic Cancer

Pancreatic cancer is the fourth leading cause of cancer-related death in the United States. Reactive oxygen species (ROS) are generally increased in pancreatic cancer cells compared with normal cells. ROS plays a vital role in various cellular biological activities including proliferation, growth, apoptosis, and invasion. Besides, ROS participates in tumor microenvironment orchestration. The role of ROS is a doubled-edged sword in pancreatic cancer. The dual roles of ROS depend on the concentration. ROS facilitates carcinogenesis and cancer progression with mild-to-moderate elevated levels, while excessive ROS damages cancer cells dramatically and leads to cell death. Based on the recent knowledge, either promoting ROS generation to increase the concentration of ROS with extremely high levels or enhancing ROS scavenging ability to decrease ROS levels may benefit the treatment of pancreatic cancer. However, when faced with oxidative stress, the antioxidant programs of cancer cells have been activated to help cancer cells to survive in the adverse condition. Furthermore, ROS signaling and antioxidant programs play the vital roles in the progression of pancreatic cancer and in the response to cancer treatment. Eventually, it may be the novel target for various strategies and drugs to modulate ROS levels in pancreatic cancer therapy.