For the past decade, there has been an increased concern about the health risks from arsenic (As) exposure, because of its neurotoxic effects on the developing brain. The exact mechanism underlying As-induced neurotoxicity during sensitive periods of brain development remains unclear, especially the role of blood-brain barrier's (BBB) tight junction (TJ) proteins during As-induced neurotoxicity. Here, we highlight the involvement of TJ proteins in As-induced autophagy in cerebral cortex and hippocampus during developmental periods [postnatal day (PND) 21, 28, 35 and 42]. Here, the administration of arsenic trioxide (As2O3) at doses of 0.15 mg or 1.5 mg or 15 mg As2O3/L in drinking water from gestational to lactational and continued to the pups till PND42 resulted in a significant decrease in the mRNA expression levels of TJ proteins (Occludin, Claudin, ZO-1 and ZO-2) and Occludin protein expression level. In addition, As exposure significantly decreased PI3K, Akt, mTOR, and p62 with a concomitant increase in Beclin1, LC3I, LC3II, Atg5 and Atg12. Moreover, As exposure also significantly downregulated the protein expression levels of mTOR with a concomitant upregulation of Beclin 1, LC3 and Atg12 in all the developmental age points. However, no significant alterations were observed in low and medium dose-exposed groups of PND42. Histopathological analysis in As-exposed mice revealed decreased number of pyramidal neurons in hippocampus; and neurons with degenerating axons, shrinkage of cells, remarkable vacuolar degeneration in cytoplasm, karyolysis and pyknosis in cerebral cortex. Ultrastructural analysis by transmission electron microscopy revealed the occurrence of autophagosomes and vacuolated axons in the cerebral cortex and hippocampus of the mice exposed to high dose As at PND21 and 42. The severities of changes were found to more persist in the cerebral cortex than in the hippocampus of As-exposed mice. Finally, we conclude that the leaky BBB in cerebral cortex and hippocampus may facilitate the transfer of As and induces autophagy by inhibiting PI3K/Akt/mTOR signaling pathway in an age-dependent manner, i.e., among the four different developmental age points, PND21 animals were found to be more vulnerable to the As-induced neurotoxicity than the other three age points.

The aim of this study was to evaluate the effects of gestational administrations of arsenic trioxide (ATO; As2O3) on fetal neuroendocrine development (the thyroid-cerebrum axis). 5 or 10 mg ATO/kg was administered to pregnant rats (Rattus norvegicus) by gavage from gestation day (GD) 1-20. Both doses of ATO showed diminished free thyroxine (FT4) and free triiodothyronine (FT3) levels, and augmented thyrotropin (TSH) level in both dams and fetuses at GD 20. Also, the maternofetal hypothyroidism in both groups resulted in a dose-dependent decrease in the fetal serum growth hormone (GH), insulin growth factor-I (IGF-I), and IGF-II at embryonic day (ED) 20. These disorders perturb the maternofetal body weight, fetal brain weight, and survival of pregnant and their fetuses. Alternatively, a destructive degeneration, vacuolation, hyperplasia, and oedema were observed in fetal thyroid and cerebrum of both ATO groups at ED 20. These disruptions appear to depend on intensification in the levels of lipid peroxidation (LPO), NO, and H2O2, suppression of mRNA expression of Nrf2 and PPARγ, and activation of mRNA expression of Caspase-3, NF-κB, and Cox2, BAX and iNOS in the fetal cerebrum. These data suggested that gestational ATO may disturb thyroid-cerebrum axis generating fetal neurodevelopmental toxicity.

Arsenic trioxide (ATO) has been reported to inhibit the activity of Ten-eleven translocation methylcytosine dioxygenase (TET). TET modulates FOXP3 expression, while dysregulation of FOXP3 expression promotes the malignant progression of leukemia cells. We examined the role of TET-FOXP3 axis in the cytotoxic effects of ATO on the human acute myeloid leukemia cell line, U937. ATO-induced apoptosis in U937 cells was characterized by activation of caspase-3/-9, mitochondrial depolarization, and MCL1 downregulation. In addition, ATO-treated U937 cells showed ROS-mediated inhibition of TET2 transcription, leading to downregulation of FOXP3 expression and in turn, suppression of FOXP3-mediated activation of Lyn and Akt. Overexpression of FOXP3 or Lyn minimized the suppressive effect of ATO on Akt activation and MCL1 expression. Promoter luciferase activity and chromatin immunoprecipitation assays revealed the crucial role of Akt-mediated CREB phosphorylation in MCL1 transcription. Further, ATO-induced Akt inactivation promoted GSK3β-mediated degradation of MCL1. Transfection of constitutively active Akt expression abrogated ATO-induced MCL1 downregulation. MCL1 overexpression lessened the ATO-induced depolarization of mitochondrial membrane and increased the viability of ATO-treated cells. Thus, our data suggest that ATO induces mitochondria-mediated apoptosis in U937 cells through its suppressive effect on TET2-FOXP3-Lyn-Akt axis-modulated MCL1 transcription and protein stabilization. Our findings also indicate that the same pathway underlies ATO-induced death in human leukemia HL-60 cells.

Crocetin, the major carotenoid in saffron, exhibits potent anticancer effects. However, the antileukemic effects of crocetin are still unclear, especially in primary acute promyelocytic leukemia (APL) cells. In the current study, the potential antipromyelocytic leukemia activity of crocetin and the underlying molecular mechanisms were investigated. Crocetin (100 µM), like standard anti-APL drugs, all-trans retinoic acid (ATRA, 10 µM) and As2 O 3 (arsenic trioxide, 50 µM), significantly inhibited proliferation and induced apoptosis in primary APL cells, as well as NB4 and HL60 cells. The effect was associated with the decreased expressions of prosurvival genes Akt and BCL2, the multidrug resistance (MDR) proteins, ABCB1 and ABCC1 and the inhibition of tyrosyl-DNA phosphodiesterase 1 (TDP1), while the expressions of proapoptotic genes CASP3, CASP9, and BAX/BCL2 ratio were significantly increased. In contrast, crocetin at relatively low concentration (10 µM), like ATRA (1 µM) and As 2 O 3 (0.5 µM), induced differentiation of leukemic cells toward granulocytic pattern, and increased the number of differentiated cells expressing CD11b and CD14, while the number of the immature cells expressing CD34 or CD33 was decreased. Furthermore, crocetin suppressed the expression of clinical marker promyelocytic leukemia/retinoic acid receptor-α ( PML/RARα) in NB4 and primary APL cells, and reduced the expression of histone deacetylase 1 ( HDAC1) in all leukemic cells. The results suggested that crocetin can be considered as a candidate for future preclinical and clinical trials of complementary APL treatment.

Arsenic trioxide (As2O3), which has been shown to be effective in treating leukemia and other solid tumors, was strictly restricted in clinical application due to its severe toxicity. The present study was performed to explore whether the combination of As2O3 and artemisinin could produce a more powerful anticancer effect and reduce the toxicity of As2O3. MTT assay was performed to detect the cell viability of A549, Hela and HepG2 cells treated with As2O3 and artemisinin. Combination index (CI) analysis was carried out to evaluate the synergistic effect of As2O3 and artemisinin. Wound healing assay was preformed to evaluate the migration rate. Fluorescent microscopy measurements and flow cytometry were carried out to evaluate the apoptosis. Besides, reactive oxygen species (ROS) was also detected with DCFH-DA. The cell proliferation assay indicated that artemisinin significantly enhanced the inhibit effect of As2O3 in a dose and time dependent manner. Combination index (CI) analysis further demonstrated that combining artemisinin with As2O3 generated synergistic effects in A549, Hela and HepG2 cells. The combination of these two drugs also evidently reduced the cell migration rate. Artemisinin also enhanced the apoptosis, necrosis in As2O3-treated A549 and Hela cells. In addition, ROS levels were increased obviously by combining artemisinin with As2O3. The present study showed that artemisinin could dramatically enhance the anticancer effects of As2O3. Combining artemisinin with As2O3 would be a novel therapeutic strategy for cancer therapy.

Intravenous arsenic trioxide (ATO) has been adopted as the first-line treatment for acute promyelocytic leukemia (APL). Another arsenic compound named the Realgar-Indigo naturalis formula (RIF), an oral traditional Chinese medicine containing As4 S4 , has been shown to be highly effective in treating adult APL. In the treatment of pediatric APL, the safety and efficacy of RIF remains to be confirmed. This randomized, multicenter and noninferiority trial was conducted to determine whether intravenous ATO can be substituted by oral RIF in the treatment of pediatric APL. From September 2011 to January 2017, among 92 patients who were 16 years old or younger with newly diagnosed PML-RARa positive APL, 82 met eligible criteria and were randomly assigned to ATO (n=42) or RIF (n=40) group. The remaining 10 patients did not fulfilled eligible criteria because 5 did not accept randomization, 4 died and 1 had hemiplegia prior to arsenic randomization due to intracranial hemorrhage or cerebral thrombosis. Induction and consolidation treatment contained ATO or RIF, all-trans-retinoic acid and low intensity chemotherapy. End points included event-free survival (EFS), adverse events and hospital days. After a median 3-year follow-up, the estimated 5-year EFS was 100% in both groups, and adverse events were mild. However, patients in the RIF group had significantly less hospital stay than those in the ATO group. This interim analysis shows that oral RIF is as effective and safe as intravenous ATO for the treatment of pediatric APL, with the advantage of reducing hospital stay. Final trial analysis will reveal mature outcome data. This article is protected by copyright. All rights reserved.

Arsenic and copper, two common environmental contaminants, presented potentially harmful to the immune system. In order to examine whether simultaneous exposure to arsenic and copper has the potential effects on immunity and inflammatory response in chicken thymus, 30 mg/kg arsenic trioxide and/or 300 mg/kg copper sulfate were added to chicken basal diet, respectively. After 12 weeks of administrations, we observed significantly decreased thymus weight and thymus index, inflammatory cell infiltration and hyperemia visible to the unaided eye. Concurrent administration arsenic and copper markedly increased levels of NF-κB, COX-2, iNOS and PTGEs and pro-inflammatory cytokines in concomitant with a tendency of Th1 bias immune response. Additionally, heat shock proteins levels were noticeably elevated in all treated groups. Above mentioned indicators were more pronounced among co-administrated groups. Collectively, arsenic and/or copper exposure engendered immunotoxicity of chicken thymus, resulting in inflammatory responses and imbalance of the immune response. Concurrent exposure of arsenic and copper was likely to potentiate the toxicity of chicken thymus and detailed mechanisms required further exploration. Heat shock proteins may play protective roles in thymus damage, and HSP60 combines with the IL-17/IL-10 ratio may be potential predictive marker of arsenic and/or copper-subchronic toxicity in chicken thymus.