Sodium arsenite induces aggresome formation by promoting PICK1 BAR domain homodimer formation.

The aggresome is a perinuclear structure that sequesters misfolded proteins. It is implicated in various neurodegenerative diseases. The perinuclear structure enriched with protein interacting with C kinase 1 (PICK1) was found to be inducible by cellular stressors, colocalizing with microtubule-organizing center markers and ubiquitin, hence classifying it as an aggresome. Sodium arsenite but not arsenate was found to potently induce aggresome formation through an integrated stress response-independent pathway. In HEK293T cells, under arsenite stress, PICK1 localization to the aggresome was prioritized, and formation of PICK1 homodimers was favored. Additionally, PICK1 could enhance protein entry into aggresomes. This study shows that arsenite can induce the formation of both RNA stress granules and aggresomes at the same time, and that PICK1 shows conditional localization to aggresomes, suggesting a possible involvement of PICK1 in neurodegenerative diseases.

The mRNA-capping enzyme localizes to stress granules in the cytoplasm and maintains cap homeostasis of target mRNAs.

The model of RNA stability has undergone a transformative shift with the revelation of a cytoplasmic capping activity that means a subset of transcripts are recapped autonomously of their nuclear counterparts. The present study demonstrates nucleo-cytoplasmic shuttling of the mRNA-capping enzyme (CE, also known as RNA guanylyltransferase and 5'-phosphatase; RNGTT), traditionally acknowledged for its nuclear localization and functions, elucidating its contribution to cytoplasmic capping activities. A unique nuclear export sequence in CE mediates XPO1-dependent nuclear export of CE. Notably, during sodium arsenite-induced oxidative stress, cytoplasmic CE (cCE) congregates within stress granules (SGs). Through an integrated approach involving molecular docking and subsequent co-immunoprecipitation, we identify eIF3b, a constituent of SGs, as an interactive associate of CE, implying that it has a potential role in guiding cCE to SGs. We measured the cap status of specific mRNA transcripts from U2OS cells that were non-stressed, stressed and recovered from stress, which indicated that cCE-target transcripts lost their caps during stress but remarkably regained cap stability during the recovery phase. This comprehensive study thus uncovers a novel facet of cytoplasmic CE, which facilitates cellular recovery from stress by maintaining cap homeostasis of target mRNAs.

Sodium arsenite and arsenic trioxide differently affect the oxidative stress of lymphoblastoid cells: An intricate crosstalk between mitochondria, autophagy and cell death.

Although the toxicity of arsenic depends on its chemical forms, few studies have taken into account the ambiguous phenomenon that sodium arsenite (NaAsO2) acts as a potent carcinogen while arsenic trioxide (ATO, As2O3) serves as an effective therapeutic agent in lymphoma, suggesting that NaAsO2 and As2O3 may act via paradoxical ways to either promote or inhibit cancer pathogenesis. Here, we compared the cellular response of the two arsenical compounds, NaAsO2 and As2O3, on the Burkitt lymphoma cell model, the Epstein Barr Virus (EBV)-positive P3HR1 cells. Using flow cytometry and biochemistry analyses, we showed that a NaAsO2 treatment induces P3HR1 cell death, combined with drastic drops in ΔΨm, NAD(P)H and ATP levels. In contrast, As2O3-treated cells resist to cell death, with a moderate reduction of ΔΨm, NAD(P)H and ATP. While both compounds block cells in G2/M and affect their protein carbonylation and lipid peroxidation, As2O3 induces a milder increase in superoxide anions and H2O2 than NaAsO2, associated to a milder inhibition of antioxidant defenses. By electron microscopy, RT-qPCR and image cytometry analyses, we showed that As2O3-treated cells display an overall autophagic response, combined with mitophagy and an unfolded protein response, characteristics that were not observed following a NaAsO2 treatment. As previous works showed that As2O3 reactivates EBV in P3HR1 cells, we treated the EBV- Ramos-1 cells and showed that autophagy was not induced in these EBV- cells upon As2O3 treatment suggesting that the boost of autophagy observed in As2O3-treated P3HR1 cells could be due to the presence of EBV in these cells. Overall, our results suggest that As2O3 is an autophagic inducer which action is enhanced when EBV is present in the cells, in contrast to NaAsO2, which induces cell death. That's why As2O3 is combined with other chemicals, as all-trans retinoic acid, to better target cancer cells in therapeutic treatments.

Molecular Evidence of the Inhibitory Potential of Melatonin against NaAsO2-Induced Aging in Male Rats.

Arsenic (As) poisoning is widespread due to exposure to pollution. The toxic level of (As) causes oxidative stress-induced aging and tissue damage. Since melatonin (MLT) has anti-oxidant and anti-aging properties, we aimed to evaluate the protective effect of MLT against the toxicity of sodium arsenite (NaAsO2). Healthy male NMRI mice were divided into eight different groups. The control group received a standard regular diet. Other groups were treated with varying diets, including MLT alone, NaAsO2, and NaAsO2 plus MLT. After one month of treatment, biochemical and pathological tests were performed on blood, heart, and lung tissue samples. NaAsO2 increased the levels of TNF-α, 8-hydroxy-2-deoxy guanosine (8OHdG), malondialdehyde (MDA), reactive oxygen species (ROS), and high mobility group box 1 (HMGB1), increased the expression of TNF receptor type 1-associated death domain (TRADD) mRNA and telomerase reverse transcriptase, and decreased the expression of Klotho (KL) mRNA in both plasma and tissues. In contrast, MLT reduced MDA, ROS, HMGB1, lactate, and TNF-α enhanced the mRNA expression of KL, and suppressed the mRNA expression of the TERT and TRADD genes. Thus, MLT confers potent protection against NaAsO2- induced tissue injury and oxidative stress.

Long non-coding RNA DICER1-AS1-low expression in arsenic-treated A549 cells inhibits cell proliferation by regulating the cell cycle pathway.

Arsenic, an environmental pollution with diverse toxicities, incurs public health problems. Arsenic trioxide could inhibit cell proliferation in vitro experiments, but the underlying mechanisms are not fully known. LncRNAs are also involved in the arsenic-induced toxicological responses. In our study, we found that the expression of lncRNA DICER1-AS1 was significantly inhibited by sodium arsenite in a dose-dependent manner. DICER1-AS1 silencing decreased the A549 cell proliferation and inhibited cell cycle progression. Importantly, DICER1-AS1 silencing induced upregulation of p21 and downregulation of Cyclin A2, Cyclin E2, CDK1 and PCNA. In conclusion, our study provided a new lncRNA-dictated regulatory mechanism participating in arsenic-induced inhibition of cell proliferation.

Design and in vitro antibiofilm activity of propolis diffusion-controlled biopolymers.

In this study, a novel pH-sensitive hydrogel beads that is based on gelatin/sodium alginate/chitosan (GEL/SA/CS) loaded with propolis ethanolic extracts (PE) were synthesized. The swelling behavior of GEL/SA/CS hydrogel beads was studied in different pH solutions and compared with unloaded CS (GEL/SA) hydrogel beads. The in vitro release studies have been revealed using four different pH (1.3, 5.0, 6.0, and 6.8), a saliva environment (pH 6.8), a simulated gastric fluid (SGF) (pH 1.3), and a simulated intestinal fluid (SIF) (pH 6.8) to simulate the physiological conditions in gastrointestinal (GI) tract. Propolis-loaded hydrogel beads were found to be stable at pH 1.3, 5.0, 6.0, simulated saliva, SGF, and SIF mediums, whereas the beads lose their stability at pH 6.8 buffer solution. Tested microorganisms displayed greater sensitivity to PE-loaded hydrogel beads compared with pure propolis. Contrary to antimicrobial activity results, antibiofilm activity results of PE-loaded GEL/SA and GEL/SA/CS hydrogel beads were found at low levels. According to the obtained results, the propolis-loaded GEL/SA/CS hydrogel beads synthesized within this study can be used in the treatment of GI tract diseases such as oral mucositis, gastric ulcer, ulcerative colitis, and GI cancer, as controlled releasing carriers of propolis.

Na2S2O8 Nanoparticles Trigger Antitumor Immunotherapy through Reactive Oxygen Species Storm and Surge of Tumor Osmolarity.

Although more attention has been attracted to the therapy based on reactive oxygen species (ROS) for tumor therapy in recent years, such as photodynamic therapy and chemodynamic therapy, the limited ROS production rate leads to their poor treatment effect owing to the relatively low content of O2 and H2O2 in tumor microenvironments, confined light penetration depth, strict Fenton reaction conditions (pH 3-4), and so on. Therefore, it is urgent to explore the new agents with highly efficient ROS generation capacity. Herein, we first prepared phospholipid coated Na2S2O8 nanoparticles (PNSO NPs) as new ROS generation agents for in situ generating Na+ and S2O82- through gradual degradation, which can then be changed to toxic •SO4- (a novel reported ROS) and •OH regardless of the amount of H2O2 and pH value in the tumor microenvironment (TME). As the generation of a large amount of Na+, PNSO NPs can bypass the ion transport rules of cells through endocytosis to deliver large amounts of Na+ into the cells, resulting in a surge of osmolarity and rapid cell rupture and lysis. Osmotic pressure induced by PNSO NPs will further lead to an unusual manner of cell death: caspase-1-related pyroptosis. Moreover, all of above effects will cause high immunogenic cell death, regulate the immunosuppressed TME, and then activate systemic antitumor immune responses to combat tumor metastasis and recurrence. We believe PNSO NPs will be new and potential ROS generation agents, and this work will broaden the thinking of the exploring of new antitumor nanodrugs.

Anti-Tumor Effects of Sodium Meta-Arsenite in Glioblastoma Cells with Higher Akt Activities.

Glioblastoma is a type of aggressive brain tumor that grows very fast and evades surrounding normal brain, lead to treatment failure. Glioblastomas are associated with Akt activation due to somatic alterations in PI3 kinase/Akt pathway and/or PTEN tumor suppressor. Sodium meta-arsenite, KML001 is an orally bioavailable, water-soluble, and trivalent arsenical and it shows antitumoral effects in several solid tumor cells via inhibiting oncogenic signaling, including Akt and MAPK. Here, we evaluated the effect of sodium meta-arsenite, KML001, on the growth of human glioblastoma cell lines with different PTEN expression status and Akt activation, including PTEN-deficient cells (U87-MG and U251) and PTEN-positive cells (LN229). The growth-inhibitory effect of KML001 was stronger in U87-MG and U251 cells, which exhibited higher Akt activity than LN229 cells. KML001 deactivated Akt and decreased its protein levels via proteasomal degradation in U87-MG cells. KML001 upregulated mutant PTEN levels via inhibition of its proteasomal degradation. KML001 inhibited cell growth more effectively in active Akt-overexpressing LN229 cells than in mock-expressing LN229 cells. Consistent with these results, KML001 sensitized PTEN-deficient cells more strongly to growth inhibition than it did PTEN-positive cells in prostate and breast cancer cell lines. Finally, we illustrated in vivo anti-tumor effects of KML001 using an intracranial xenograft mouse model. These results suggest that KML001 could be an effective chemotherapeutic drug for the treatment of glioblastoma cancer patients with higher Akt activity and PTEN loss.

Arsenic compounds activate the MAPK and caspase pathways to induce apoptosis in OEC­M1 gingival epidermal carcinoma.

Arsenic is a well­documented environmental toxicant that can induce neurotoxicity and peripheral vascular diseases. In fact, arsenic trioxide has been used to treat various cancer types. Oral cancer has been in the top ten common cancers for decades in Taiwan, and the incidence rate is continuously increasing. The majority of oral cancers are associated with excessive tobacco, alcohol consumption and betel chewing. To the best of our knowledge, no study has revealed the effect of arsenic compounds on oral cancers. Thus, the present study used OEC­M1 oral squamous carcinoma cells treated with sodium arsenite (NaAsO2) and dimethylarsenic acid (DMA) to determine whether both arsenic compounds could exert anticancer effects on oral cancer. The results demonstrated that NaAsO2 and DMA induced rounding up and membrane blebbing in OEC­M1 cells, which are morphological characteristics of apoptosis. Annexin V/PI double staining analysis further confirmed that both arsenic compounds induced apoptosis of OEC­M1 cells. In addition, NaAsO2 and DMA significantly decreased the survival rate and increased the percentage of OEC­M1 cells in the subG1 and G2/M phases (P<0.05). Furthermore, both arsenic compounds significantly activated the cleavage of caspase­8, ­9, ­3 and PARP, and the phosphorylation of JNK, ERK1/2 and p38 in OEC­M1 cells (P<0.05). Collectively, the findings of the present study indicated that NaAsO2 and DMA stimulate extrinsic and intrinsic apoptotic pathways through the activation of the MAPK pathways to induce apoptosis of OEC­M1 cells, suggesting that NaAsO2 and DMA may be used as novel anticancer drugs for oral cancers.

Arsenite suppresses the transcriptional activity of EVI1 through the binding to CCHC-type Zn finger domain.

Transcription factor EVI1 is essential for normal hematopoiesis in embryos but is aberrantly elevated in bone marrow cells of myelodysplastic syndrome (MDS) patients. EVI1 and its downstream GATA-2 appear to be a possible therapeutic target of MDS. Here we found that treatment of EVI1-expressing K562 cells with arsenite (As(III)) reduced the mRNA and protein levels of EVI1 and GATA-2. A gel shift assay using the nuclear extract of K562 cells showed that As(III) suppressed the DNA-binding activity of EVI1. The DNA-binding activity of the recombinant EVI1 protein was also suppressed by As(III) but was recovered by excess amounts of dithiothreitol, suggesting the involvement of cysteine residues of EVI1. Since the 7th Zn finger domain of EVI1, having a motif of CCHC, is known to be involved in DNA-binding, the synthetic peptide of 7th Zn finger domain was reacted with As(III) and subjected to MALDI-TOF-MS analysis. The results showed that As(III) binds to this peptide via three cysteine residues. As(III)-induced reduction of the DNA-binding activity of the recombinant EVI1 was abolished by the mutations of each of three cysteine residues to alanine in the 7th Zn finger domain. These results demonstrate that As(III) causes the down-regulation of EVI1 and GATA-2 by inhibiting the transcriptional activity of EVI1 through the binding to the cysteine residues of CCHC-type Zn finger domain.

Increased expression and retention of the secretory chaperone proSAAS following cell stress.

The secretory pathway of neurons and endocrine cells contains a variety of mechanisms designed to combat cellular stress. These include not only the unfolded protein response pathways but also diverse chaperone proteins that collectively work to ensure proteostatic control of secreted and membrane-bound molecules. One of the least studied of these chaperones is the neural- and endocrine-specific molecule known as proSAAS. This small chaperone protein acts as a potent anti-aggregant both in vitro and in cellulo and also represents a cerebrospinal fluid biomarker in Alzheimer's disease. In the present study, we have examined the idea that proSAAS, like other secretory chaperones, might represent a stress-responsive protein. We find that exposure of neural and endocrine cells to the cell stressors tunicamycin and thapsigargin increases cellular proSAAS mRNA and protein in Neuro2A cells. Paradoxically, proSAAS secretion is inhibited by these same drugs. Exposure of Neuro2A cells to low concentrations of the hypoxic stress inducer cobalt chloride, or to sodium arsenite, an oxidative stressor, also increases cellular proSAAS content and reduces its secretion. We conclude that the cellular levels of the small secretory chaperone proSAAS are positively modulated by cell stress.

SVCT2-Dependent plasma and mitochondrial membrane transport of ascorbic acid in differentiating myoblasts.

The Na+-dependent Vitamin C transporter 2 (SVCT2) is expressed in the plasma and mitochondrial membranes of various cell types. This notion was also established in proliferating C2C12 myoblasts (Mb), in which the transporter was characterised by a high and low affinity in the plasma and mitochondrial membranes, respectively. In addition, the mitochondrial expression of SVCT2 appeared particularly elevated and, consistently, a brief pre-exposure to low concentrations of Ascorbic Acid (AA) abolished mitochondrial superoxide formation selectively induced by the cocktail arsenite/ATP. Early myotubes (Mt) derived from these cells after 4 days of differentiation presented evidence of slightly increased SVCT2 expression, and were characterised by kinetic parameters for plasma membrane transport of AA in line with those detected in Mb. Confocal microscopy studies indicated that the mitochondrial expression of SVCT2 is well preserved in Mt with one or two nuclei, but progressively reduced in Mt with three or more nuclei. Cellular and mitochondrial expression of SVCT2 was found reduced in day 7 Mt. While the uptake studies were compromised by the poor purity of the mitochondrial preparations obtained from day 4 Mt, we nevertheless obtained evidence of poor transport of the vitamin using the same functional studies successfully employed with Mb. Indeed, even greater concentrations of/longer pre-exposure to AA failed to induce scavenging of mitochondrial superoxide in Mt. These results are therefore indicative of a severely reduced mitochondrial uptake of the vitamin in early Mt, attributable to decreased expression as well as impaired activity of mitochondrial SVCT2.

Coupling of translation quality control and mRNA targeting to stress granules.

Stress granules are dynamic assemblies of proteins and nontranslating RNAs that form when translation is inhibited in response to diverse stresses. Defects in ubiquitin-proteasome system factors including valosin-containing protein (VCP) and the proteasome impact the kinetics of stress granule induction and dissolution as well as being implicated in neuropathogenesis. However, the impacts of dysregulated proteostasis on mRNA regulation and stress granules are not well understood. Using single mRNA imaging, we discovered ribosomes stall on some mRNAs during arsenite stress, and the release of transcripts from stalled ribosomes for their partitioning into stress granules requires the activities of VCP, components of the ribosome-associated quality control (RQC) complex, and the proteasome. This is an unexpected contribution of the RQC system in releasing mRNAs from translation under stress, thus identifying a new type of stress-activated RQC (saRQC) distinct from canonical RQC pathways in mRNA substrates, cellular context, and mRNA fate.

Chronic arsenic exposure impairs adaptive thermogenesis in male C57BL/6J mice.

The global prevalence of type 2 diabetes (T2D) has doubled since 1980. Human epidemiological studies support arsenic exposure as a risk factor for T2D, although the precise mechanism is unclear. We hypothesized that chronic arsenic ingestion alters glucose homeostasis by impairing adaptive thermogenesis, i.e., body heat production in cold environments. Arsenic is a pervasive environmental contaminant, with more than 200 million people worldwide currently exposed to arsenic-contaminated drinking water. Male C57BL/6J mice exposed to sodium arsenite in drinking water at 300 µg/L for 9 wk experienced significantly decreased metabolic heat production when acclimated to chronic cold tolerance testing, as evidenced by indirect calorimetry, despite no change in physical activity. Arsenic exposure increased total fat mass and subcutaneous inguinal white adipose tissue (iWAT) mass. RNA sequencing analysis of iWAT indicated that arsenic dysregulated mitochondrial processes, including fatty acid metabolism. Western blotting in WAT confirmed that arsenic significantly decreased TOMM20, a correlate of mitochondrial abundance; PGC1A, a master regulator of mitochondrial biogenesis; and, CPT1B, the rate-limiting step of fatty acid oxidation (FAO). Our findings show that chronic arsenic exposure impacts the mitochondrial proteins of thermogenic tissues involved in energy expenditure and substrate regulation, providing novel mechanistic evidence for arsenic's role in T2D development.

Arsenic-induced immunomodulatory effects disorient the survival-death interface by stabilizing the Hsp90/Beclin1 interaction.

Ground water arsenic contamination is a global menace. Since arsenic may affect the immune system, leading to immunesuppression, we investigated the effects of acute arsenic exposure on the thymus and spleen using Swiss albino mice, exposed to 5 ppm, 15 ppm and 300 ppm of sodium arsenite for 7 d. Effects on cytokine balance and cell survivability were subsequently analyzed. Our data showed that arsenic treatment induced debilitating alterations in the tissue architecture of thymus and spleen. A dose-dependent decrease in the ratio of CD4+-CD8+ T-cells was observed along with a pro-inflammatory response and redox imbalance. In addition, pioneering evidences established the ability of arsenic to induce an up regulation of Hsp90, eventually resulting in stabilization of its client protein Beclin-1, an important autophagy-initiating factor. This association initiated the autophagic process, confirmed by co-immunoprecipitation assay, acridine orange staining and Western blot, indicating the effort of cells trying to survive at lower doses. However, increased arsenic assault led to apoptotic cell death in the lymphoid organs, possibly by increased ROS generation. There are several instances of autophagy and apoptosis taking place either simultaneously or sequentially due to oxidative stress. Since arsenic is a potent environmental stress factor, exposure to arsenic led to a dose-dependent increase in both autophagy and apoptosis in the thymus and spleen, and cell death could therefore possibly be induced by autophagy. Therefore, exposure to arsenic leads to serious effects on the immune physiology in mice, which may further have dire consequences on the health of exposed animals.

Naturally-derived diterpenoid sphaeropsidin C as an activator of Nrf2/ARE pathway and its potential capability of relieving intracellular oxidative stress in human lung epithelial cells.

Oxidative stress is closely associated to the onset and progression of many human diseases. Activation of the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway using naturally-derived molecules is an efficient strategy for alleviating the intracellular oxidative insults, and thus blocking the pathogenesis of oxidative stress-induced diseases. In the present study, a naturally-derived isopimarane-type diterpenoid sphaeropsidin C (SC) was identified to be an activator of Nrf2/ARE signaling pathway. Our data indicated that SC was able to stimulate Nrf2-mediated defensive system through promoting Nrf2 translocation, inhibiting Nrf2 ubiquitination, and enhancing Nrf2 stability in normal human lung epithelial Beas-2B cells. Furthermore, SC-induced Nrf2 activation required the involvement of protein kinases, exemplified by protein kinase C (PKC), protein kinase R-like endoplasmic reticulum kinase (PERK), and phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K). It alleviated sodium arsenite [As(III)]-induced intracellular oxidative stress in an Nrf2-dependent manner. These results suggested that SC displayed potential application for the prevention and therapy against oxidative stress-induced diseases. Moreover, isopimarane-type diterpenoid represents a promising skeleton for developing Nrf2 activators.

AggreCount: an unbiased image analysis tool for identifying and quantifying cellular aggregates in a spatially defined manner.

Protein quality control is maintained by a number of integrated cellular pathways that monitor the folding and functionality of the cellular proteome. Defects in these pathways lead to the accumulation of misfolded or faulty proteins that may become insoluble and aggregate over time. Protein aggregates significantly contribute to the development of a number of human diseases such as amyotrophic lateral sclerosis, Huntington's disease, and Alzheimer's disease. In vitro, imaging-based, cellular studies have defined key biomolecular components that recognize and clear aggregates; however, no unifying method is available to quantify cellular aggregates, limiting our ability to reproducibly and accurately quantify these structures. Here we describe an ImageJ macro called AggreCount to identify and measure protein aggregates in cells. AggreCount is designed to be intuitive, easy to use, and customizable for different types of aggregates observed in cells. Minimal experience in coding is required to utilize the script. Based on a user-defined image, AggreCount will report a number of metrics: (i) total number of cellular aggregates, (ii) percentage of cells with aggregates, (iii) aggregates per cell, (iv) area of aggregates, and (v) localization of aggregates (cytosol, perinuclear, or nuclear). A data table of aggregate information on a per cell basis, as well as a summary table, is provided for further data analysis. We demonstrate the versatility of AggreCount by analyzing a number of different cellular aggregates including aggresomes, stress granules, and inclusion bodies caused by huntingtin polyglutamine expansion.

Serum Proteomic Profiling Analysis of Rats Chronically Exposed to Arsenic.

BACKGROUND Arsenic (As) is an environmental contaminant, and As pollution in water and soil is a public health issue worldwide. As exposure is associated with the incidence of many disorders, such as arteriosclerosis, diabetes, neurodegenerative diseases, and renal dysfunction. However, the mechanism of As toxicity remains unclear. MATERIAL AND METHODS We investigated the changes in serum protein profiles of rats chronically exposed to As. Twenty healthy rats were randomly divided into 4 groups, and sodium arsenite of varying final concentrations (0, 2, 10, and 50 mg/L, respectively) was add into the drinking water for each group. The administration lasted for 3 months. Two proteomic strategies, isobaric tags for relative and absolute quantitation (iTRAQ), and 2-dimensional gel electrophoresis (2-DE), were employed to screen the differential serum proteins between control and arsenite exposure groups. RESULTS We identified a total of 27 differentially-expressed proteins, among which 9 proteins were significantly upregulated and 18 were downregulated by As exposure. Many of the differentially-expressed proteins were related to fat digestion and absorption, including 5 apolipoproteins, which indicated lipid metabolism may be the most affected by As exposure. CONCLUSIONS This study revealed the influence of As on lipid metabolism, suggesting an increased potential risk of relevant diseases in subjects chronically exposed to As.

In vitro application of sodium arsenite to mice testicular and epididymal organ cultures induces oxidative, biochemical, hormonal, and genotoxic stress.

Arsenic poisoning is well-known for its innumerable toxic and carcinogenic effects. In vivo data on reproductive toxicity are also known but in vitro data are scant. Presently, we evaluated the in vitro toxic effects of sodium arsenite (NaAsO2) on adult mice testes and epididymal tissues using organ cultures. Testicular and epididymal fragments were incubated at 37°C and 33°C, respectively, with 1, 10, 50, and 100 µM concentrations of NaAsO2. Cultures were allowed to incubate for 2 and 24 h. Levels of oxidative stress markers, the reactive oxygen species (ROS) and thiobarbituric acid reactive substance assay (TBARS), antioxidant enzymes, testosterone concentrations, and the extent of sperm DNA damage, were estimated. Results were analyzed statistically at p < 0.05. Results demonstrated both time- and dose-dependent alterations whereby, following 24-h incubation with NaAsO2, substantial increases were noticeable in ROS and TBARS levels and sperm DNA damage (p < 0.001), while decreases (p < 0.001) occurred in catalase, peroxidase, and superoxide dismutase levels at 10, 50, and 100 µM concentrations. Incubations for 2 h revealed similar but relatively less toxic effects. Testosterone concentrations decreased significantly only after 24 h of incubation with 50 (1.95 vs. 2.93 ng g-1; p < 0.01) and 100 µM (1.32 vs. 2.93 ng g-1; p < 0.001) NaAsO2 concentrations. The study concluded that exposure of testicular and epididymal tissue fragments to arsenic under in vitro conditions induces rapid and immediate metabolic and genotoxic damage at higher concentrations.

Sodium Arsenite Inhibits Lung Fibroblast Differentiation and Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial lung disease with a high mortality and poor prognosis. Transforming growth factor (TGF)-ß plays crucial roles in the pathogenesis of IPF. To investigate the role of sodium arsenite (SA) on fibroblast differentiation and pulmonary fibrosis, we checked the effects of SA on TGF-ß-induced normal human lung fibroblasts (NHLFs) differentiation, and the anti-fibrotic effect of SA on bleomycin (BLM)-induced pulmonary fibrosis in mouse. SA treatment significantly inhibits α-smooth muscle actin and fibronectin (FN) expression in TGF-ß treated NHLFs; and SA also inhibits TGF-ß stimulated expression of NADPH oxidase 4 and accumulation of intracellular reactive oxygen species. TGF-ß-induced the phosphorylation of ERK and Smad3 were also blocked by SA. The administration of SA (IP) suppressed BLM-induced lung fibrosis characterized as the inhibition of collagen deposition, TGF-ß accumulation in bronchoalveolar lavage fluid, and the expression of FN and collagen 1a2 in lung tissue. This study revealed that SA inhibits TGF-ß-induced lung fibroblast differentiation and BLM-induced pulmonary fibrosis in mice, suggesting that SA could be a potential therapeutic approach to IPF.