Balance between the toxicity and anticancer activity of arsenic trioxide in treatment of acute promyelocytic leukemia

Therapeutic potential of xtr-miR-22-3p from Plastrum testudinis in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is marked by a block at the promyelocyte stage. Treatments like ATRA and ATO face resistance and relapse issues. Plastrum testudinis, a traditional Chinese medicine, may offer therapeutic potential. This study investigated xtr-miR-22-3p from P. testudinis for treating APL. High expression of xtr-miR-22-3p was confirmed, with target prediction indicating interactions with key genes, including PML. xtr-miR-22-3p reduced HL-60 leukemia cell growth, altered the cell cycle, and selectively inhibited HL-60 proliferation while promoting BMSC growth, suggesting its potential as a targeted APL therapy.

Nicorandil mitigates arsenic trioxide-induced lung injury via modulating vital signalling pathways SIRT1/PGC-1α/TFAM, JAK1/STAT3, and miRNA-132 expression

BACKGROUND AND PURPOSE

Nicorandil, a selective opener of potassium channels, used to treat angina, has drawn attention for its potential in mitigating lung injury, positioning it as a promising therapeutic approach to treat drug-induced lung toxicity. This study aimed to explore the protective role of nicorandil in arsenic trioxide (ATO)-induced lung injury and to elucidate the underlying mechanistic pathways.

EXPERIMENTAL APPROACH

We assessed the effects of nicorandil (15 mg·kg-1, p.o.) in a rat model of pulmonary injury induced by ATO (5 mg·kg-1, i.p.). The assessment included oxidative stress biomarkers, inflammatory cytokine levels, and other biomarkers, including sirtuin-1, sirtuin-3, STAT3, TFAM, and JAK in lung tissue. Histological examination using H&E staining and molecular investigations using western blotting and PCR techniques were conducted.

KEY RESULTS

In our model of lung injury, treatment with nicorandil ameliorated pathological changes as seen with H&E staining, reduced tissue levels of toxicity markers, and exerted significant antioxidant and anti-inflammatory actions. On a molecular level, treatment with nicorandil down-regulated JAK, STAT3, PPARγ, Nrf2, VEGF, p53, and micro-RNA 132 while up-regulating Sirt1, 3, TFAM, AMPK, and ERR-α in lung tissue.

CONCLUSIONS AND IMPLICATIONS

The results presented here show nicorandil as a significant agent in attenuating lung injury induced by ATO in a rodent model. Nonetheless, further clinical studies are warranted to strengthen these findings.

Targeting mutant p53 with arsenic trioxide: A preclinical study focusing on triple negative breast cancer

New treatments are urgently required for triple-negative breast cancer (TNBC). As TP53 is mutated in approximately 80% of TNBC, it is theoretically an attractive target for new drugs for this disease. Arsenic trioxide (ATO), which is used to treat promyelocytic leukaemia, was recently shown to reactivate mutant p53 and restore wild-type functionality. The aim of this study was to evaluate ATO as a potential new treatment for TNBC. Using a panel of 20 cell lines, we found that TNBC cell lines were more sensitive to ATO than non-TNBC cell lines (P = 0.045). Consistent with its ability to reactivate mutant p53, ATO was a more potent inhibitor of proliferation in cell lines with mutant TP53 than the wildtype TP53 (P = 0.027). Direct evidence of mutant p53 reactivation was the induction of multiple wild-type p53 canonical target genes such as CDKN1A, SLC7A11, BBC3, PMAIP1, SESN2, SRXN1 and TXNRD1. Our findings support the activation of mutant p53 by ATO and, furthermore, the possible repurposing of ATO to treat TP53-mutated TNBC.

Visual Hallucinations With Arsenic Trioxide Therapy in Acute Promyelocytic Leukemia

A 68-year-old male with a history of diabetes and hypertension was diagnosed with acute promyelocytic leukemia (APML). He underwent induction therapy with all-trans retinoic acid (ATRA) and arsenic trioxide. He had a complete hematologic response and was initiated on consolidation therapy with arsenic trioxide (0.15 mg/kg/day intravenous (IV)) and ATRA (45 mg/per meter square of body surface area/day IV). He developed blurred vision and floaters after a few days. Soon after, he felt that his diabetic neuropathy had suddenly worsened. The floaters and flashing lights worsened and morphed into visual hallucinations. He reported seeing figures watching him from the corner of the room. He was admitted and head imaging was unremarkable. Routine labs did not show anything unusual. Arsenic trioxide therapy was held. The hallucinations gradually started decreasing and eventually subsided after around eight weeks. ATRA was continued but arsenic was permanently discontinued. Arsenic is known to cause poisoning if exposed in significant amounts. The arsenic dose used for APML is substantially low (0.15 mg/kg/day IV). We delineate this unanticipated case of arsenic toxicity leading to severe neurological symptoms like visual hallucinations which has not been previously reported in the literature. It is imperative to closely monitor patients who are on arsenic therapy and inform them about possible rare toxicities.

Alteration of Hepatic Cytochrome P450 Expression and Arachidonic Acid Metabolism by Arsenic Trioxide (ATO) in C57BL/6 Mice

The success of arsenic trioxide (ATO) in acute promyelocytic leukemia has driven a plethora studies to investigate its efficacy in other malignancies. However, the inherent toxicity of ATO limits the expansion of its clinical applications. Such toxicity may be linked to ATO-induced metabolic derangements of endogenous substrates. Therefore, the primary objective of this study was to investigate the effect of ATO on the hepatic formation of arachidonic acid (AA) metabolites, hydroxyeicosatetraenoic acids (HETEs), as well as their most notable producing machinery, cytochrome P450 (CYP) enzymes. For this purpose, C57BL/6 mice were intraperitoneally injected with 8 mg/kg ATO for 6 and 24 h. Total RNA was extracted from harvested liver tissues for qPCR analysis of target genes. Hepatic microsomal proteins underwent incubation with AA, followed by identification/quantification of the produced HETEs. ATO downregulated Cyp2e1, while induced Cyp2j9 and most of Cyp4a and Cyp4f, and this has resulted in a significant increase in 17(S)-HETE and 18(R)-HETE, while significantly decreased 18(S)-HETE. Additionally, ATO induced Cyp4a10, Cyp4a14, Cyp4f13, Cyp4f16, and Cyp4f18, resulting in a significant elevation in 20-HETE formation. In conclusion, ATO altered hepatic AA metabolites formation through modulating the underlying network of CYP enzymes. Modifying the homeostatic production of bioactive AA metabolites, such as HETEs, may entail toxic events that can, at least partly, explain ATO-induced hepatotoxicity. Such modification can also compromise the overall body tolerability to ATO treatment in cancer patients.

Arsenic trioxide: applications, mechanisms of action, toxicity and rescue strategies to date

Arsenical medicine has obtained its status in traditional Chinese medicine for more than 2,000 years. In the 1970s, arsenic trioxide was identified to have high efficacy and potency for the treatment of acute promyelocytic leukemia, which promoted many studies on the therapeutic effects of arsenic trioxide. Currently, arsenic trioxide is widely used to treat acute promyelocytic leukemia and various solid tumors through various mechanisms of action in clinical practice; however, it is accompanied by a series of adverse reactions, especially cardiac toxicity. This review presents a comprehensive overview of arsenic trioxide from preclinical and clinical efficacy, potential mechanisms of action, toxicities, and rescue strategies for toxicities to provide guidance or assistance for the clinical application of arsenic trioxide.

Clinical Indicators of Hepatotoxicity in Newly Diagnosed Acute Promyelocytic Leukemia Patients Undergoing Arsenic Trioxide Treatment

Arsenic trioxide (ATO)-induced hepatotoxicity is often observed in acute promyelocytic leukemia (APL) patients and decreases therapeutic effect of ATO. Thus, concerns over hepatotoxicity have been raised. The aim of this study was to explore some noninvasive clinical indicators that can be used to guide the individualized application of ATO in the future. APL patients treated with ATO were identified retrospectively via electronic health records at our hospital from August 2014 through August 2019. APL patients without hepatotoxicity were selected as controls. The association between putative risk factors and ATO-induced hepatotoxicity was estimated with ORs and 95% CIs, which were calculated using the chi-square test. The subsequent multivariate analysis was performed using logistic regression analysis. In total, 58.04% of patients experienced ATO-induced hepatotoxicity during the first week. Elevated hemoglobin (OR 8.653, 95% CI, 1.339-55.921), administration of nonprophylactic hepatoprotective agents (OR 36.455, 95% CI, 7.409-179.364), non-single-agent ATO to combat leukocytosis (OR 20.108, 95% CI, 1.357-297.893) and decreased fibrinogen (OR 3.496, 95% CI, 1.127-10.846) were found to be statistically significant risk factors for ATO-induced hepatotoxicity. The area under the ROC curve values were 0.846 for "overall ATO-induced hepatotoxicity" and 0.819 for "early ATO-induced hepatotoxicity." The results revealed that hemoglobin ≥ 80 g/L, nonprophylactic hepatoprotective agents, and non-single-agent ATO and fibrinogen < 1 g/L are risk factors for ATO-induced hepatotoxicity in newly diagnosed APL patients. These findings can enhance the clinical diagnosis of hepatotoxicity. Prospective studies should be performed in the future to validate these findings.

Differential modulation of cytochrome P450 enzymes by arsenicals in non-human experimental models

Arsenic is a hazardous heavy metalloid that imposes threats to human health globally. It is widely spread throughout the environment in various forms. Arsenic-based compounds are either inorganic compounds (iAs) or organoarsenicals (oAs), where the latter are biotically generated from the former. Exposure to arsenic-based compounds results in varying biochemical derangements in living systems, leading eventually to toxic consequences. One important target for arsenic in biosystems is the network of metabolic enzymes, especially the superfamily of cytochrome P450 enzymes (CYPs) because of their prominent role in both endobiotic and xenobiotic metabolism. Therefore, the alteration of the CYPs by different arsenicals has been actively studied in the last few decades. We have previously summarized the findings of former studies investigating arsenic associated modulation of different CYPs in human experimental models. In this review, we focus on non-human models to get a complete picture about possible CYPs alterations in response to arsenic exposure.

Effect of Long-Term Low-Dose Arsenic Exposure on DNA Methylation and Gene Expression in Human Liver Cells

Millions of people around the world are exposed to elevated levels of arsenic through food or drinking water. Epidemiological studies have linked chronic arsenic exposure to an increased risk of several cancers, cardiovascular disease, central nervous system neuropathies, and genotoxic as well as immunotoxic effects. In addition to the induction of oxidative stress and inhibition of DNA repair processes, epigenetic effects, including altered DNA methylation patterns resulting in aberrant gene expression, may contribute to carcinogenicity. However, the underlying mechanisms by which chronic micromolar concentrations of arsenite affect the methylation status of DNA are not fully understood. In this study, human HepG2 hepatocarcinoma cells were treated with 0.5-10 μM sodium arsenite for 24 h, 10, or 20 days. During these periods, the effects on global DNA methylation, cell cycle phase distribution, and gene expression were investigated. While no impact on DNA methylation was seen after short-term exposure, global hypomethylation was observed at both long-term exposure periods, with concomitant induction of the DNA methyltransferase genes DNMT1 and DNMT3B, while DNMT3A was slightly down-regulated. Pronounced time- and concentration-dependent effects were also seen in the case of genes involved in DNA damage response and repair, inflammation, oxidative stress response, and metal homeostasis. These results suggest that chronic low-dose arsenite exposure can lead to global hypomethylation. As an underlying mechanism, the consistent down-regulation of DNA methyltransferase genes could be excluded; alternatively, interactions at the protein level could play an important role.

The landscape of novel strategies for acute myeloid leukemia treatment: Therapeutic trends, challenges, and future directions

Acute myeloid leukemia (AML) is a highly heterogeneous subtype of hematological malignancies with a wide spectrum of cytogenetic and molecular abnormalities, which makes it difficult to manage and cure. Along with the deeper understanding of the molecular mechanisms underlying AML pathogenesis, a large cohort of novel targeted therapeutic approaches has emerged, which considerably expands the medical options and changes the therapeutic landscape of AML. Despite that, resistant and refractory cases caused by genomic mutations or bypass signalling activation remain a great challenge. Therefore, discovery of novel treatment targets, optimization of combination strategies, and development of efficient therapeutics are urgently required. This review provides a detailed and comprehensive discussion on the advantages and limitations of targeted therapies as a single agent or in combination with others. Furthermore, the innovative therapeutic approaches including hyperthermia, monoclonal antibody-based therapy, and CAR-T cell therapy are also introduced, which may provide safe and viable options for the treatment of patients with AML.

Torsemide increases arsenic concentrations by inhibition of multidrug resistance protein 4 in arsenic trioxide treated acute promyelocytic leukemia patients

Torsemide is commonly used to relieve edema during the treatment of acute promyelocytic leukemia (APL) with arsenic trioxide (ATO). We explored the effect of torsemide on the plasma concentrations of inorganic arsenic (iAs), monomethylarsonic acid (MMA^V) and dimethyarsinic acid (DMA^V) in APL patients treated with ATO and clarified its molecular mechanism in rats and cells. The study included 146 APL patients treated with ATO. 60（41.1 %) of these 146 patients were co-administered with torsemide. The treatment of torsemide increased plasma concentrations of iAs (P < 0.05) and DMA^V (P < 0.05) in APL patients. The single co-administration of ATO and torsemide in rats significantly increased the plasma concentrations and AUC_(0-t) of iAs (P < 0.05) and MMA^V (P < 0.05), decreased the urinary excretion rates and the urine concentrations of iAs (P < 0.05) and DMA^V (P < 0.05), and enhanced iAs (P < 0.05) and MMA^V (P < 0.05) concentrations in the kidneys of rats. In addition, torsemide decreased the expression of multidrug resistance protein 4 (MRP4) in rat kidneys after 7 days of continuous co-administration (P < 0.05). We also treated MRP4-overexpressing HEK293T cells with ATO and different concentrations of torsemide. Torsemide markedly increased the concentrations of iAs, MMA^V and DMA^V by inhibiting MRP4 compared with ATO alone (P < 0.05). In conclusion, torsemide increased the plasma concentrations of arsenic metabolites in APL patients treated with ATO by inhibiting the transporter MRP4 in a dose-dependent manner.

Monomethylarsonous acid binds to Cys-104α and Cys-112β of hemoglobin in acute promyelocytic leukemia patients treated with arsenic trioxide

Arsenic trioxide (As₂O₃) has prominent effect in treating acute promyelocytic leukemia (APL). Identification of arsenic-binding proteins has gained attention for their important biological functions. However, none has been published concerning the binding mechanism of arsenic with hemoglobin (Hb) in APL patients after treatment of As₂O₃. The present study discloses the binding sites of arsenic on Hb in APL patients. Concentrations of inorganic arsenic (iAs), monomethyl arsenic (MMA), and dimethyl arsenic (DMA) in erythrocytes of APL patients were quantified using HPLC-inductively coupled plasma-mass spectroscopy (HPLC-ICP-MS). Hb-bound arsenic was identified by size-exclusion chromatography ICP-MS. The binding sites of arsenic on Hb were determined by mass spectrometry (MS). The concentration trend of arsenic species in erythrocytes of 9 APL patients treated with As₂O₃ was iAs>MMA>DMA, and MMA was the predominant methylated arsenic metabolite. Size-exclusion chromatography separation of free and protein-bound arsenic by simultaneous monitoring of ⁵⁷Fe and ⁷⁵As demonstrated the presence of Hb-bound arsenic. MS information suggested monomethylarsonous (MMA^III) was the dominant arsenic bound to Hb, and further identified that Cys-104α and Cys-112β were two binding sites of MMA^III in Hb. MMA^III binding to Cys-104α and Cys-112β was responsible for arsenic accumulation in erythrocytes of APL patients. This interaction may contribute to understand the therapeutic effect of As₂O₃ as an anticancer drug and its toxicity on APL patients.

Investigating the effect of myricetin against arsenic-induced cardiac toxicity in rats

Arsenic intoxication is a serious health hazard worldwide. Its toxicity is associated with several disorders and health problems in humans. Recent studies revealed that myricetin has various biological effects, including anti-oxidation. The aim of this study is to investigate the protective effect of myricetin against arsenic-induced cardiotoxicity in rats. Rats were randomized to one of the following groups: control, myricetin (2 mg/kg), arsenic (5 mg/kg), myricetin (1 mg/kg) + arsenic, and myricetin (2 mg/kg) + arsenic. Myricetin was given intraperitoneally 30 min before arsenic administration (5 mg/kg for 10 days). After treatments, the activity of lactate dehydrogenase (LDH) and the levels of aspartate aminotransferase (AST), creatine kinase myocardial band (CK-MB), lipid peroxidation (LPO), total antioxidant capacity (TAC), and total thiol molecules (TTM) were determined in serum samples and cardiac tissues. Also, histological changes in cardiac tissue were evaluated. Myricetin pretreatment inhibited arsenic-induced increase in LDH, AST, CK-MB, and LPO levels. Pretreatment with myricetin also enhanced the decreased TAC and TTM levels. In addition, myricetin improved histopathological alterations in arsenic-treated rats. In conclusion, the results of the present study demonstrated that treatment with myricetin prevented arsenic-induced cardiac toxicity at least in part by decreasing oxidative stress and restoring the antioxidant system.

The Impact of Long-Term Clinoptilolite Administration on the Concentration Profile of Metals in Rodent Organisms

Heavy metals are dangerous systemic toxicants that can induce multiple organ damage, primarily by inducing oxidative stress and mitochondrial damage. Clinoptilolite is a highly porous natural mineral with a magnificent capacity to eliminate metals from living organisms, mainly by ion-exchange and adsorption, thus providing detoxifying, antioxidant and anti-inflammatory medicinal effects. The in vivo efficiency and safety of the oral administration of clinoptilolite in its activated forms, tribomechanically activated zeolite (TMAZ) and Panaceo-Micro-Activated (PMA) zeolite, as well as the impact on the metallic biodistribution, was examined in healthy female rats. Concentration profiles of Al, As, Cd, Co, Pb, Ni and Sr were measured in rat blood, serum, femur, liver, kidney, small and large intestine, and brain using inductively coupled plasma mass spectrometry (ICP-MS) after a 12-week administration period. Our results point to a beneficial effect of clinoptilolite materials on the concentration profile of metals in female rats supplemented with the corresponding natural clinoptilolite materials, TMAZ and PMA zeolite. The observed decrease of measured toxicants in the kidney, femur, and small and large intestine after three months of oral intake occurred concomitantly with their most likely transient release into the bloodstream (serum) indicative of a detoxification process.

Breast Cancer and Arsenic Anticancer Effects: Systematic Review of the Experimental Data from In Vitro Studies

Arsenic is a known environmental carcinogenic agent. However, under certain circumstances, it may exert anticancer effects. In this systematic review, we aim to provide information on recent developments in studies on arsenic antitumor effects in breast cancer. Research included in the review refers to experimental data from in vitro studies. The data was collected using search terms "breast cancer," "arsenic," and "anticancer" (25.05.2021). Only studies in English and published in the last 10 years were included. The search identified 123 studies from the EBSCOhost, PubMed, and Scopus databases. In the selection process, thirty full-texts were evaluated as eligible for the review. The literature of the last decade provides a lot of information on mechanisms behind anticancer effects of arsenic on breast cancer. Similar to arsenic-induced carcinogenesis, these mechanisms include the activation of the redox system and the increased production of free radicals. Targets of arsenic action are systems of cell membranes, mitochondria, pathways of intracellular transmission, and the genetic apparatus of the cell. Beneficial effects of arsenic use are possible due to significant metabolic differences between cancer and healthy cells. Further efforts are needed in order to establish modes and doses of treatment with arsenic that would provide anticancer activity with minimal toxicity.

Poison With a Purpose: A Case Report on Arsenic Cardiotoxicity and Obesity

Acute promyelocytic leukemia (APL) is a form of leukemia in which there is an arrest of the maturation of the myeloid lineage at the promyelocyte stage. Although there is high early mortality due to coagulopathy, APL is now a curable disease with the use of arsenic trioxide (ATO) and all-trans-retinoic acid (ATRA). Arsenic is weight-based for the treatment of APL, and many toxicities are dose-dependent, although there are no guidelines regarding dosing adjustments for obese patients. We present a case of a 34-year-old male with obesity and APL who developed arsenic-induced QTc prolongation and symptomatic sinus tachycardia while receiving treatment. Further research is needed to guide appropriate dosing for obese patients to determine if ideal body weight dosing is able to provide similar cure rates with fewer adverse events.

Exosomes: A novel insight into traditional Chinese medicine

Exosomes are small extracellular vesicles and play an essential role in the mediation of intercellular communication both in health and disease. Traditional Chinese medicine (TCM) has historically been used to maintain human health and treat various diseases up till today. The interplay between exosomes and TCM has attracted researchers’ growing attention. By integrating the available evidence, TCM formulas and compounds isolated from TCM as exosome modulators have beneficial effects on multiple disorders, such as tumors, kidney diseases, and hepatic disease, which may associate with inhibiting cells proliferation, anti-inflammation, anti-oxidation, and attenuating fibrosis. Exosomes, a natural delivery system, are essential in delivering compounds isolated from TCM to target cells or tissues. Moreover, exosomes may be the potential biomarkers for TCM syndromes, providing strategies for TCM treatment. These findings may provide a novel insight into TCM from exosomes and serve as evidence for better understanding and development of TCM.

Down-regulation of hepatic cytochromes P450 1A1 and 1A2 by arsenic trioxide (ATO) in vivo and in vitro: A role of heme oxygenase 1

Arsenic trioxide (ATO) has evolved from an environmental threat to a successful therapy for acute promyelocytic leukemia (APL) and probably for solid tumors in the future. However, its efficacy comes at a cost of multi-organ toxicity whose mechanism remains unresolved. Arsenicals have been reported to modulate cytochrome P450 1A (CYP1A) enzymes, thus modifying activation/detoxification of drugs/procarcinogens. Therefore, this study aimed to investigate the possible effects of ATO on CYP1A1 and CYP1A2, in absence and presence of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) using in vivo and in vitro models. For this purpose, C57BL/6 mice were intraperitoneally injected with 8 mg/kg ATO with or without 15 μg/kg TCDD for 6 and 24 h. Furthermore, HepG2 cells were treated with ATO (1, 5, and 10 μM) with or without 1 nM TCDD for 6 and 24 h. ATO significantly inhibited TCDD-mediated induction of CYP1A1/1A2 mRNA, protein, and activity in both models. ATO differentially modulated CYP1A1/1A2 basal levels in vivo. We also demonstrated that ATO downregulates CYP1A through inhibiting the transcriptional activation of its regulatory element at both basal and inducible levels. Additionally, ATO significantly induced mRNA and protein of heme oxygenase 1 (HMOX1) in vivo and in vitro. In HepG2 cells, inhibition of HMOX1 by tin (IV) mesoporphyrin (IX) (SnMP) resulted in a partial restoration of the TCDD-mediated induction of CYP1A1 activity that was inhibited by ATO co-exposure. Our findings show that ATO alters both constitutive and inducible CYP1A1/1A2 expressions through transcriptional and HMOX1-mediated post-translational mechanisms. This implies the possible involvement of ATO in clearance-related consequences for the substrates of these enzymes such as drug-drug interactions or suboptimal toxicant elimination.

Arsenic Trioxide Therapy During Pregnancy: ATO and Its Metabolites in Maternal Blood and Amniotic Fluid of Acute Promyelocytic Leukemia Patients

Acute promyelocytic leukemia (APL) is extremely fatal if treatment is delayed. Management of APL in pregnancy is a challenging situation. Arsenic trioxide (ATO) is successfully applied to treat APL. ATO can be transformed into different arsenic species [arsenite (As^III), monomethylated arsenic (MMA, consists of MMA^III and MMA^V), dimethylated arsenic (DMA, consists of DMA^III and DMA^V), and arsenate (As^V)], which produce different toxic effects. Investigating the maternal and fetal exposure to arsenic species is critical in terms of assessing maternal and fetal outcomes, choice of optimal treatment, and making decisions for attempting to preserve the obstetrical and fetal wellbeing. In this study, maternal blood and amniotic fluid (AF) from APL patients treated with ATO in pregnancy and blood samples of non-pregnant patients were collected. Concentrations of inorganic arsenic (iAs, iAs = As^III+As^V), MMA, and DMA were analyzed by high-performance liquid chromatography–hydride generation–atomic fluorescence spectrometry (HPLC–HG–AFS). The difference in arsenic species of plasma between pregnant patients and non-pregnant patients, distribution of arsenic compounds in AF and maternal plasma, and arsenic penetration into AF were explored. The outcomes of pregnant women treated with ATO and their fetus were analyzed. No significant differences in arsenic concentration, percentage, and methylation index [PMI: primary methylation index (MMA/iAs); SMI: secondary methylation index (DMA/MMA)] between pregnant women and non-pregnant women (p > 0.05) were observed. The mean ratios of AF to maternal plasma were as follows: iAs, 2.09; DMA, 1.04; MMA, 0.49; and tAs, 0.98. Abortion rate is higher with the diagnosis at an earlier gestational age, with 0%, 67%, and 100% of pregnancies ending in abortion during the third, second, and first trimester, respectively. The age of the pregnant women, the dose of ATO, and the duration of fetal exposure in utero had no influence on fetal outcomes. All APL women achieved complete remission (CR). Collectively, ATO and its metabolites can easily cross the placenta. Levels and distribution of arsenic species in maternal plasma and AF gave evidence that arsenic species had a different ability to penetrate the placenta into AF (iAs > DMA > MMA) and indicated a relatively high fetal exposure to ATO and its metabolites in utero. Gestational age at diagnosis was more likely to be closely related to fetal outcomes, but had no effects on mother outcomes.

Blockade of deubiquitinase YOD1 degrades oncogenic PML/RARα and eradicates acute promyelocytic leukemia cells

In most acute promyelocytic leukemia (APL) cells, promyelocytic leukemia (PML) fuses to retinoic acid receptor α (RARα) due to chromosomal translocation, thus generating PML/RARα oncoprotein, which is a relatively stable oncoprotein for degradation in APL. Elucidating the mechanism regulating the stability of PML/RARα may help to degrade PML/RARα and eradicate APL cells. Here, we describe a deubiquitinase (DUB)-involved regulatory mechanism for the maintenance of PML/RARα stability and develop a novel pharmacological approach to degrading PML/RARα by inhibiting DUB. We utilized a DUB siRNA library to identify the ovarian tumor protease (OTU) family member deubiquitinase YOD1 as a critical DUB of PML/RARα. Suppression of YOD1 promoted the degradation of PML/RARα, thus inhibiting APL cells and prolonging the survival time of APL cell-bearing mice. Subsequent phenotypic screening of small molecules allowed us to identify ubiquitin isopeptidase inhibitor I (G5) as the first YOD1 pharmacological inhibitor. As expected, G5 notably degraded PML/RARα protein and eradicated APL, particularly drug-resistant APL cells. Importantly, G5 also showed a strong killing effect on primary patient-derived APL blasts. Overall, our study not only reveals the DUB-involved regulatory mechanism on PML/RARα stability and validates YOD1 as a potential therapeutic target for APL, but also identifies G5 as a YOD1 inhibitor and a promising candidate for APL, particularly drug-resistant APL treatment.

A Metabolic Profiling Study of Realgar-Induced Acute Kidney Injury in Mice

Realgar has been used as a type of mineral drug that contains arsenic for thousands of years. Previous studies have shown that Realgar-induced acute kidney injury is associated with abnormal metabolism, but the underlying mechanism is poorly understood. The aim of this study is to investigate the metabolic changes in serum and kidney tissues of mice exposed to Realgar by using a metabolomic approach and explore the molecular mechanisms of acute kidney injury induced by Realgar. Forty mice were randomly divided into four groups: Control group, 0.5-, 1.0, and 2.0 g/kg Realgar group. After 1 week, the body weight and kidney weight of the mice were measured. The serum and kidney samples were used for LC-MS spectroscopic metabolic profiling. Principal component analysis (PCA), correlation analysis, and pathway analysis were used to detect the nephrotoxic effects of Realgar. Body weight decreased significantly in the 2.0 g/kg group, and the kidney weight index also showed a dose-dependent increase in Realgar. The PCA score plot showed the serum and kidney tissue metabolic profile of mice exposed to 2.0 g/kg Realgar separated from the control group, while the lower-doses of 0.5 g/kg and 1.0 g/kg Realgar shown a similar view to the Control group. Thirty-three metabolites and seventeen metabolites were screened and identified in the serum and kidney of mice in a dose-dependent manner. respectively. Correlation analysis showed a strong correlation among these metabolites. Amino acid metabolism, lipid metabolism, glutathione metabolism, and purine metabolism pathways were found to be mainly associated with Realgar nephrotoxicity. This work illustrated the metabolic alterations in Realgar-induced nephrotoxic mice through a metabolomic approach.

Investigation of the ameliorative effects of baicalin against arsenic trioxide-induced cardiac toxicity in mice

Baicalin (BA), a kind of flavonoids compound, comes from Scutellaria baicalensis Georgi (a kind of perennial herb) and has beneficial effects on the cardiovascular system through anti-oxidant, anti-inflammation, and anti-apoptosis actions. However, the therapeutic effects and latent mechanisms of BA on arsenic trioxide (ATO)-induced cardiac toxicity has not been reported. The present research was performed to explore the effects and mechanisms of BA on ATO-induced heart toxicity. Male Kunming mice were treated with ATO (7.5 mg/kg) to induce cardiac toxicity. After the mice received ATO, BA (50 and 100 mg/kg) was administered for estimating its cardioprotective effects. Statistical data demonstrated that BA treatment alleviated electrocardiogram abnormalities and pathological injury caused by ATO. BA could also lead to recovery of CK and LDH activities to normal range and cause a decrease in MDA levels and ROS generation, augmentation of SOD, CAT, and GSH activities. We also found that BA caused a reduction in the expression of proinflammatory cytokines, such as TNF-α and IL-6. Moreover, BA attenuated ATO-induced apoptosis by promoting the expression of Bcl-2 and suppressing the expression of Bax and caspase-3. TUNEL test result demonstrated BA caused impediment of ATO-induced apoptosis. Furthermore, BA treatment suppressed the high expression of TLR4, NF-κB and P-NF-κB caused by ATO. In conclusion, these results indicate that BA may alleviate ATO-induced cardiac toxicity by restraining oxidative stress, apoptosis, and inflammation, and its mechanism would be associated with the inhibition of the TLR4/NF-κB signaling pathway.

Effect of renal impairment on arsenic accumulation, methylation capacity, and safety in acute promyelocytic leukemia (APL) patients treated with arsenic trioxide

Background: Arsenic trioxide (ATO) was successfully applied to treat acute promyelocytic leukemia (APL).Methods: Inorganic arsenic (iAs), monomethylarsonic acid (MMA^V) and dimethyarsinic acid (DMA^V) in plasma of 143 APL patients with different renal function were determined. Arsenic methylation capacity was evaluated by iAs%, MMA^V%, DMA^V%, primary methylation index (PMI, MMA^V/iAs), and secondary methylated index (SMI, DMA^V/MMA^V). Arsenic accumulation with administration frequency were explored. Moreover, safety assessments were performed.Results: Compared with normal renal function, MMA^V and DMA^V concentrations increased 1.5-4 fold in moderate and severe renal impairment groups, iAs increased 1.3-1.7 fold. APL patients with renal impairment showed lower iAs%, but higher DMA^V% and PMI in plasma than those with normal renal function (P < 0.05). MMA^V, DMA^V, and tAs apparently accumulated with administration frequency in moderate and severe renal dysfunction groups. The incidence of QTc interval prolongation and liver injury increased with the increasing severity of renal impairment.Conclusion: Renal dysfunction may increase exposure to arsenic and arsenic accumulation and affect methylation capacity, then the clinical safety in APL patients treated with ATO. Arsenic-level monitoring and dosing regimen adjustment should be considered in APL patients with moderate and severe renal dysfunction.

Arsenic toxicity manifesting as profuse watery diarrhea during induction therapy for acute promyelocytic leukemia

Arsenic trioxide (ATO) is generally well tolerated for treatment of APL. We present a patient with severe watery diarrhea and pancreatitis thought to be due to ATO toxicity in the setting of obesity and acute kidney injury. Future studies evaluating ATO levels in patients experiencing toxicities may help guide dose modifications.

Overview of all-trans-retinoic acid (ATRA) and its analogues: Structures, activities, and mechanisms in acute promyelocytic leukaemia

All-trans-retinoic acid (ATRA) is effective for preventing cancer and treating skin diseases and acute promyelocytic leukaemia (APL). These pharmacological effects of ATRA are mainly mediated by retinoid X receptors (RXRs) and retinoic acid receptors (RARs). This article provides a comprehensive overview of the clinical progress on and the molecular mechanisms of ATRA in the treatment of APL. ATRA can promote the transcriptional activation of differentiation-related genes and regulate autophagy by inhibiting mTOR, which results in anti-APL effects. In detail, the structures, pharmacological effects, and clinical studies of 68 types of ATRA analogues are described. These compounds have excellent antitumour therapeutic potential and could be used as lead compounds for further development and research.