Arsenic methylation metabolism and liver injury of acute promyelocytic leukemia patients undergoing arsenic trioxide treatment

Analysis of the occurrence and liver function characteristics of arsenic-associated liver injury during the treatment of pediatric patients with acute promyelocytic leukemia

Liver injury during arsenic treatment for acute promyelocytic leukemia was previously reported in adults, but not comprehensively in children until now. This study aims to investigate liver injury in pediatric patients with APL, changes in liver function during treatment, and compare the effects of Arsenic trioxide (ATO) and Realgar-Indigo naturalis formula (RIF) on liver function. One hundred and eighty-six patients with 3076 patient tests were analyzed, who were enrolled in the Chinese Children's Leukemia Group (CCLG)-APL2016 Protocol database between November 2016 and November 2018 in 38 hospitals across China(ChiCTR-OIN-17011227). Twenty of 164 patients (12.2%) suffered from liver injury after treatment with arsenic. In addition, sixteen (80%) cases of liver injury occurred during the induction period of treatment. What's not disheartening was that 18 (90%) cases of liver injury were transient, occurring at a median time of 17 days after exposure to arsenic. More importantly, the risk of liver injury associated with RIF was not higher than that associated with ATO (RR = 0.854, 95% CI: 0.292-2.495). Otherwise, the ALP of 18 cases of liver injury was not higher than the ULN of ALP. Thus, the incidence of liver injury associated with arsenic in pediatric patients with APL was similar to that in adult patients and the risk of liver injury associated with RIF was not higher than that associated with ATO. Since ALP was not higher in pediatric APL patients with liver injury, further research is needed to explore whether ALP is an index of liver injury in children.

Copper, Iron, Cadmium, and Arsenic, All Generated in the Universe: Elucidating Their Environmental Impact Risk on Human Health Including Clinical Liver Injury

Humans are continuously exposed to various heavy metals including copper, iron, cadmium, and arsenic, which were specifically selected for the current analysis because they are among the most frequently encountered environmental mankind and industrial pollutants potentially causing human health hazards and liver injury. So far, these issues were poorly assessed and remained a matter of debate, also due to inconsistent results. The aim of the actual report is to thoroughly analyze the positive as well as negative effects of these four heavy metals on human health. Copper and iron are correctly viewed as pollutant elements essential for maintaining human health because they are part of important enzymes and metabolic pathways. Healthy individuals are prepared through various genetically based mechanisms to maintain cellular copper and iron homeostasis, thereby circumventing or reducing hazardous liver and organ injury due to excessive amounts of these metals continuously entering the human body. In a few humans with gene aberration, however, liver and organ injury may develop because excessively accumulated copper can lead to Wilson disease and substantial iron deposition to hemochromatosis. At the molecular level, toxicities of some heavy metals are traced back to the Haber Weiss and Fenton reactions involving reactive oxygen species formed in the course of oxidative stress. On the other hand, cellular homeostasis for cadmium and arsenic cannot be provided, causing their life-long excessive deposition in the liver and other organs. Consequently, cadmium and arsenic represent health hazards leading to higher disability-adjusted life years and increased mortality rates due to cancer and non-cancer diseases. For unknown reasons, however, liver injury in humans exposed to cadmium and arsenic is rarely observed. In sum, copper and iron are good for the human health of most individuals except for those with Wilson disease or hemochromatosis at risk of liver injury through radical formation, while cadmium and arsenic lack any beneficial effects but rather are potentially hazardous to human health with a focus on increased disability potential and risk for cancer. Primary efforts should focus on reducing the industrial emission of hazardous heavy metals.

Urine Self-Sampling Kit Combined with an Automated Preparation-Sampler Device for Convenient and Reliable Analysis of Arsenic Metabolites by HPLC-ICPMS

Speciation analysis of arsenic in urine is essential for the studies of arsenic metabolism and biological effects, but the unstable arsenic species represented by MMAIII and DMAIII pose a huge challenge to analytical accuracy. Herein, a novel urine self-sampling (USS) kit combined with an automated preparation-sampler (APS) device is rationally designed and used for convenient analysis of arsenic metabolites by high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS). The subject can collect urine into a sampling vial at home and use a homemade syringe to pump argon to displace oxygen in the vial, thereby inhibiting the oxidation of MMAIII and DMAIII. After USS and transportation, the sampling vial is loaded directly onto the APS device, where the urine sample can be automatically mixed with diluent, filtered, and loaded into HPLC-ICPMS for arsenic speciation analysis under anaerobic conditions. For a single sample, the sampling time and the analysis time are <8 and <18 min, respectively. The recoveries of MMAIII and DMAIII in urine over 24 h at 4 °C are 86 and 67%, surpassing the conventional sampling method by 28 and 67%, respectively. When the APS is coupled to HPLC-ICPMS, the detection limits of AsC, iAsIII, MMAIII, DMAV, MMAV, DMAIII, and iAsV are 0.03-0.10 μg L-1 with precisions of <10%. The present method provides a convenient and reliable tool for the storage and analysis of unstable arsenic species in urine and lays the foundation for studying the metabolic and biological effects of methylated trivalent arsenicals.

Type 2 diabetes affects arsenic metabolism via transporters in arsenic trioxide treated acute promyelocytic leukemia patients

Our study aimed to explore whether type 2 diabetes (T2DM) can affect arsenic metabolism in acute promyelocytic leukemia (APL) patients treated with arsenic trioxide. We found that compared with non-diabetic APL patients, the concentrations of arsenic metabolites in APL patients with T2DM increased significantly and positively correlated with blood glucose (P < 0.05). Meanwhile, APL patients with T2DM were more prone to liver injury and QTc interval prolongation due to altered arsenic methylation capacity. Then we cultured HEK293T cells at different glucose concentrations, and the results showed that the cells with high glucose had higher concentrations of arsenic metabolites compared to other cells. Meanwhile, the high glucose significantly increased the mRNA and protein expression levels of the arsenic uptake transporter AQP7 in HEK293T cells. Overall, our study demonstrated that T2DM can lead to elevated concentrations of arsenic metabolites in APL patients by increasing AQP7 expression.

Diosmin exerts hepatoprotective and antihyperglycemic effects against sodium arsenite-induced toxicity through the modulation of oxidative stress and inflammation in mice

BACKGROUND

Chronic exposure to high concentrations of inorganic arsenic (NaAsO₂) in drinking water is related to an increase in the risk of liver toxicity and diabetes. Diosmin has various pharmacological properties, including antioxidant and anti-inflammatory properties. This study was designed to investigate the protective effects of diosmin on diabetes and hepatotoxicity caused by NaAsO₂.

METHODS

Sixty male 8-week-old NMRI mice, weighing 25 ± 2 g, were randomly selected and put into six groups. The control (Group 1) was treated orally with distilled water, group 2 was treated with diosmin (100 mg/kg, p.o), group 3 received NaAsO₂ (10 mg/kg, p.o), and groups 4, 5, 6 received diosmin (25, 50, 100 mg/kg, p.o), respectively and NaAsO₂ (10 mg/kg, p.o). After 29 days, fasting blood sugar (FBS) measurement and glucose tolerance test were done. The mice were sacrificed on day 31, and blood and tissue (liver and pancreas) samples were taken. Then, serum and tissue samples were studied for biochemical and histological evaluations.

RESULTS

The results demonstrated that diosmin ameliorated glucose intolerance and decreased FBS compared to the NaAsO₂ group. Diosmin (50 and 100 mg/kg) improved the serum factors of liver function (alanine aminotransferase, aspartate transaminase, and alkaline phosphatase) in the groups receiving NaAsO₂. Moreover, increased levels of nitric oxide, tumor necrosis factor-alpha, and thiobarbituric acid reactive substances in liver tissue induced by NaAsO₂ were diminished by diosmin treatment. Administration of diosmin increased total thiol and enzymatic activities of catalase, superoxide dismutase, and glutathione peroxidase in liver tissue. Furthermore, treatment with diosmin reduced the increase in protein amount of Sirtuin 3 and nuclear factor kappa B in the groups receiving NaAsO₂. Also, the liver and pancreas histological lesions induced by NaAsO₂ were attenuated by diosmin treatment.

CONCLUSION

Diosmin has a preventive effect against hepatotoxicity and diabetes induced by NaAsO₂ in mice through its antioxidant and anti-inflammatory properties.

Metabolic and residual characteristic of different arsenic species contained in laver during mouse digestion

Laver is one of the major arsenic contributors to human diets. The study on metabolic and residual characteristic of each arsenic species contained in laver is important to scientifically assess the intake risk of arsenic in the laver. The metabolic and residual characteristic of main arsenic species in laver, namely arsenate [As(V)], dimethylarsinic acid [DMA(V)] and two arsenosugars, was investigated by mouse experiments in this study. The results showed that the intake of higher-dose laver did not lead to a notable increase of As(V) concentration in mouse muscle/organs and feces. In contrast, DMA(V) excretion in feces and DMA(V) residue in muscle/organs showed a close correlation with laver-dose intake. Most DMAsSugarMethoxy was translated into other arsenic species and then was together excreted out via mouse feces; two dominant arsenic species, arsenosugar DMAsSugarMethoxy and DMAsSugarPhosphate, were not detected in mouse muscle/organs after 20-Day or 30-Day feeding whether in lower-dose laver groups containing 1/36 (mass ratio) of the laver in mouse feed or higher-dose laver groups containing 1/6 (mass ratio) of the laver in mouse feed. About 65-77% of total arsenic digested by mouse was excreted out via feces; only 0.12-0.78% of it was accumulated in mouse organs/muscle. The results of this study provided valuable knowledge for comprehending the stability and metabolic characteristics of different arsenic species from Fujian laver in vivo, also for more scientifically assessing the intake risk of arsenic in laver.

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.

Pharmacokinetic Characteristics, Tissue Bioaccumulation and Toxicity Profiles of Oral Arsenic Trioxide in Rats: Implications for the Treatment and Risk Assessment of Acute Promyelocytic Leukemia

Oral arsenic trioxide (ATO) has demonstrated a favorable clinical efficiency in the treatment of acute promyelocytic leukemia (APL). However, the pharmacokinetic characteristics, tissue bioaccumulation, and toxicity profiles of arsenic metabolites in vivo following oral administration of ATO have not yet been characterized. The present study uses high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) to assess the pharmacokinetics of arsenic metabolites in rat plasma after oral and intravenous administration of 1 mg kg^-1 ATO. In addition, the bioaccumulation of arsenic metabolites in blood and selected tissues were evaluated after 28 days oral administration of ATO in rats at a dose of 0, 2, 8, and 20 mg kg^-1 d^-1. The HPLC-HG-AFS analysis was complemented by a biochemical, hematological, and histopathological evaluation conducted upon completion of ATO treatment. Pharmacokinetic results showed that arsenite (As^III) reached a maximum plasma concentration rapidly after initial dosing, and the absolute bioavailability of As^III was 81.03%. Toxicological results showed that the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and white blood cells (WBC) in the 20 mg kg^-1 d^-1 ATO group were significantly increased compared to the control group (p < 0.05). The distribution trend of total arsenic in the rat was as follows: whole blood > kidney > liver > heart. Dimethylated arsenic (DMA) was the predominant bioaccumulative metabolite in the whole blood, liver, and heart, while monomethylated arsenic (MMA) was the predominant one in the kidney. Collectively, these results revealed that oral ATO was rapidly absorbed, well-tolerated, and showed organ-specific and dose-specific bioaccumulation of arsenic metabolites. The present study provides preliminary evidence for clinical applications and the long-term safety evaluation of oral ATO in the treatment of APL.

Importance of monitoring arsenic methylation metabolism in acute promyelocytic leukemia patients receiving the treatment of arsenic trioxide

BACKGROUND

Arsenic trioxide [ATO, inorganic arsenite (iAs^III) in solution] plays an important role in the treatment of acute promyelocytic leukemia (APL). However, the long-term adverse effects (AEs) and the retention of arsenic among APL patients are rarely reported. In this study, we focused on arsenic methylation metabolism and its relationship with chronic hepatic toxicity, as we previously reported, among APL patients who had finished the treatment of ATO.

METHODS

A total of 112 de novo APL patients who had completed the ATO-containing treatment were enrolled in the study. Arsenic species [iAs^III, inorganic arsenate (iAs^V), and their organic metabolites, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)] in patients' plasma, urine, hair and nails were detected by high-performance liquid chromatography combined with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Eighteen single nucleotide polymorphisms (SNPs) of the arsenic (+ 3 oxidative state) methylation transferase (AS3MT) gene, which was known as the main catalyzer for arsenic methylation, were tested with the polymerase chain reaction method.

RESULTS

The study showed the metabolic pattern of arsenic in APL patients undergoing and after the treatment of ATO, in terms of total arsenic (TAs) and four species of arsenic. TAs decreased to normal after 6 months since cessation of ATO. But the arsenic speciation demonstrated significantly higher portion of iAs^III in patient's urine (40.08% vs. 1.94%, P < 0.001), hair (29.25% vs. 13.29%, P = 0.002) and nails (30.21% vs. 13.64%, P = 0.003) than the healthy controls', indicating a decreased capacity of arsenic methylation metabolism after the treatment of ATO. Urine primary methylation index (PMI) was significantly lower in patients with both chronic liver dysfunction (0.14 vs. 0.28, P = 0.047) and hepatic steatosis (0.19 vs. 0.3, P = 0.027), suggesting that insufficient methylation of arsenic might be related to chronic liver disorders. Two SNPs (A9749G and A27215G) of the AS3MT gene were associated with impaired urine secondary methylation index (SMI).

CONCLUSIONS

The long-term follow-up of arsenic speciation indicated a decreased arsenic methylation metabolism and a probable relationship with chronic hepatic disorders among APL patients after the cessation of ATO. Urine PMI could be a monitoring index for chronic AEs of ATO, and the SNPs of AS3MT gene should be considered when determining the dosage of ATO.

Polymorphisms in arsenic (+ 3 oxidation state) methyltransferase (AS3MT) predict the occurrence of hyperleukocytosis and arsenic metabolism in APL patients treated with As2O3

Polymorphisms in arsenic (+ 3 oxidation state) methyltransferase (AS3MT) have been shown to be related to interindividual variations in arsenic metabolism and to influence adverse health effects in acute promyelocytic leukemia (APL) patients treated with arsenic trioxide (As₂O₃). The occurrence of hyperleukocytosis with As₂O₃ treatment seriously affects the early survival rate of APL patients, but no definite explanation for such a complication has been clearly established. To clarify the causes of this situation, AS3MT polymorphisms 14215 (rs3740390), 14458 (rs11191439), 27215 (rs11191446), and 35991 (rs10748835) and profiles of plasma arsenic metabolites were evaluated in a group of 54 newly diagnosed APL patients treated with single-agent As₂O₃. High-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) was used to determine the concentrations of plasma arsenic metabolites. Plasma arsenic methylation metabolism capacity was evaluated by the percentage of inorganic arsenic (iAs), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), primary methylation index (PMI, MMA/iAs), and secondary methylation index (SMI, DMA/MMA). The results showed that APL patients who developed hyperleukocytosis had a higher plasma iAs%, but a lower MMA% and PMI than those who did not develop hyperleukocytosis during As₂O₃ treatment. In addition, patients with the AS3MT 14215 (rs3740390) CC genotype had significantly higher plasma iAs% and incidence of hyperleukocytosis, but lower PMI than patients with the CT + TT genotype. Conversely, we did not observe statistically significant associations between the occurrence of hyperleukocytosis and AS3MT 14458 (rs11191439), 27215 (rs11191446), and 35991 (rs10748835) polymorphisms in our study subjects. These results indicated that AS3MT 14215 (rs3740390) might be used as an indicator for predicting the occurrence of hyperleukocytosis in APL patients treated with As₂O₃.

Influence of AS3MT polymorphisms on arsenic metabolism and liver injury in APL patients treated with arsenic trioxide

Arsenic-induced side effects limit its application in the treatment of acute promyelocytic leukemia (APL). We recently demonstrated that AS3MT 14215 (rs3740390) genotypes were associated with urinary arsenic metabolites and hematological and biochemical values. To further decipher the role of AS3MT genotypes on arsenic metabolism and toxicity, AS3MT 27215 (rs11191446), 35587 (rs11191453), 35991 (rs10748835), and their interactive effects were examined in fifty APL patients treated with arsenic trioxide (As₂O₃) for the first time. Urinary arsenic metabolites and methylation capacity indexes were evaluated by the percentage of inorganic arsenic (iAs), monomethylarsonate (MMA), dimethylarsinate (DMA), primary methylation index (PMI, MMA/iAs), secondary methylation index (SMI, DMA/MMA), and total methylation index (TMI, [MMA+DMA]/iAs). Results showed 27215 (rs11191446) genotypes had no statistical significance in arsenic metabolism, as only 5 (10%) patients were the non-wild-type genotypes. 35587 (rs11191453) genotypes were significantly associated with MMA%, DMA%, and SMI. 35991 (rs10748835) genotypes were significantly associated with iAs%, DMA%, PMI, TMI, and the level of ALT and AST. Patients with both 35587 (rs11191453) TT and 35991 (rs10748835) AG+GG genotypes were significantly associated with DMA% and SMI. In addition, patients with both 35991 (rs10748835) AA and 35587 (rs11191453) TC+CC genotypes had the highest DMA%, SMI, and TMI, but the lowest iAs%, ALT and AST level, indicating that additive effects exist on arsenic metabolism and liver function. Our data promotes the realization that AS3MT 35587 (rs11191453), 35991 (rs10748835), especially their joint genotypes 35991 (rs10748835) AA / 35587 (rs11191453) TC+CC, is a novel predictive biomarker for the therapeutic efficacy of As₂O₃ in the treatment of APL.

Role of arsenic (+3 oxidation state) methyltransferase in arsenic mediated APL treatment: an in vitro investigation

Arsenic (+3 oxidation state) methyltransferase (AS3MT) is a key enzyme responsible for arsenic metabolism in humans, which facilitates conversion of arsenic trioxide (As2O3) to more reactive metabolites such as monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII). However, it is unclear whether the biotransformation of arsenic by AS3MT contributes to the promotion of acute promyelocytic leukemia (APL) therapy. In order to understand the probable role of AS3MT in APL patients, we evaluated the effects of arsenite (iAsIII) and three mixed arsenicals (i.e., iAsIII, MMAIII and DMAIII, to mimic active arsenic species in the blood) on NB4 cell differentiation and apoptosis. Although the mixed arsenicals exhibited about 2 fold less effect on the induction of NB4 cell differentiation and PML-RARα fusion protein degradation, they showed 5 times stronger ability to induce apoptosis when compared with iAsIII. More importantly, the proliferation of NB4 cells was significantly (p < 0.05) inhibited in a transwell system co-cultured with AS3MT-transfected HepG2 cells after exposure to iAsIII, suggesting that the generation of methylated metabolites restrained cell proliferation. These findings indicate that the therapeutic efficacy of As2O3 (i.e., iAsIII) in APL patients is probably associated with the production of methylated arsenic metabolites (i.e., MMAIII and DMAIII) by AS3MT.

Analysis of Four Types of Leukemia Using Gene Ontology Term and Kyoto Encyclopedia of Genes and Genomes Pathway Enrichment Scores

AIM AND OBJECTIVE

Leukemia is the second common blood cancer after lymphoma, and its incidence rate has an increasing trend in recent years. Leukemia can be classified into four types: acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), and chronic myelogenous leukemia (CML). More than forty drugs are applicable to different types of leukemia based on the discrepant pathogenesis. Therefore, the identification of specific drug-targeted biological processes and pathways is helpful to determinate the underlying pathogenesis among such four types of leukemia.

METHODS

In this study, the gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways that were highly related to drugs for leukemia were investigated for the first time. The enrichment scores for associated GO terms and KEGG pathways were calculated to evaluate the drugs and leukemia. The feature selection method, minimum redundancy maximum relevance (mRMR), was used to analyze and identify important GO terms and KEGG pathways.

RESULTS

Twenty Go terms and two KEGG pathways with high scores have all been confirmed to effectively distinguish four types of leukemia.

CONCLUSION

This analysis may provide a useful tool for the discrepant pathogenesis and drug design of different types of leukemia.

Lipidomic profiling of subchronic As4S4exposure identifies inflammatory mediators as sensitive biomarkers in rats

Arsenic sulfide compounds provide nearly all of the world's supply of arsenic.

Insights into the All-trans-Retinoic Acid and Arsenic Trioxide Combination Treatment for Acute Promyelocytic Leukemia: A Meta-Analysis

BACKGROUND

This study aimed to compare the curative effects of the combination therapy of all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO, As₂O₃) with ATRA monotherapy on newly diagnosed acute promyelocytic leukemia (APL).

METHODS

The studies were retrieved from PubMed, EMBASE, Cochrane Library, ChinaInfo and China National Knowledge Infrastructure (CNKI) databases from the inception to June 20, 2014. Thereafter, the eligible studies were selected based on the predefined criteria, and the literature quality was assessed. The meta-analysis was conducted using Review Manager 5.2 software. The pooled effect size was relative risk (RR) and its 95% confidence interval (CI).

RESULTS

A total of 8 studies containing 480 cases were included, among which 264 were assigned to the ATRA + ATO group and the other 216 to the ATRA group. The meta-analysis showed that ATRA + ATO combination therapy significantly improved the complete remission (CR) rate (RR = 1.09, 95% CI = 1.03-1.16, p = 0.004), decreased the early mortality rate (RR = 0.42, 95% CI = 0.20-0.9, p = 0.03) and relapse rate (RR = 0.17, 95% CI = 0.07-0.42, p < 0.0001), but increased the high risk of liver dysfunction (RR = 2.43, 95% CI = 1.72-3.41, p < 0.00001), comparing with ATRA monotherapy.

CONCLUSIONS

The ATRA + ATO combination therapy may be more effective for newly diagnosed APL with a higher CR rate but lower early mortality rate and relapse rate. However, the risks of liver damage should be of concern.

Rapid reduction in breast cancer mortality with inorganic arsenic in drinking water

BACKGROUND

Arsenic trioxide is effective in treating promyelocytic leukemia, and laboratory studies demonstrate that arsenic trioxide causes apoptosis of human breast cancer cells. Region II in northern Chile experienced very high concentrations of inorganic arsenic in drinking water, especially in the main city Antofagasta from 1958 until an arsenic removal plant was installed in 1970.

METHODS

We investigated breast cancer mortality from 1950 to 2010 among women in Region II compared to Region V, which had low arsenic water concentrations. We conducted studies on human breast cancer cell lines and compared arsenic exposure in Antofagasta with concentrations inducing apoptosis in laboratory studies.

FINDINGS

Before 1958, breast cancer mortality rates were similar, but in 1958-1970 the rates in Region II were half those in Region V (rate ratio RR = 0·51, 95% CI 0·40-0·66; p<0·0001). Women under the age of 60 experienced a 70% reduction in breast cancer mortality during 1965-1970 (RR=0·30, 0·17-0·54; p<0·0001). Breast cancer cell culture studies showed apoptosis at arsenic concentrations close to those estimated to have occurred in people in Region II.

INTERPRETATION

We found biologically plausible major reductions in breast cancer mortality during high exposure to inorganic arsenic in drinking water which could not be attributed to bias or confounding. We recommend clinical trial assessment of inorganic arsenic in the treatment of advanced breast cancer.

Protective effect of curcumin against heavy metals-induced liver damage

Occupational or environmental exposures to heavy metals produce several adverse health effects. The common mechanism determining their toxicity and carcinogenicity is the generation of oxidative stress that leads to hepatic damage. In addition, oxidative stress induced by metal exposure leads to the activation of the nuclear factor (erythroid-derived 2)-like 2/Kelch-like ECH-associated protein 1/antioxidant response elements (Nrf2/Keap1/ARE) pathway. Since antioxidant and chelating agents are generally used for the treatment of heavy metals poisoning, this review is focused on the protective role of curcumin against liver injury induced by heavy metals. Curcumin has shown, in clinical and preclinical studies, numerous biological activities including therapeutic efficacy against various human diseases and anti-hepatotoxic effects against environmental or occupational toxins. Curcumin reduces the hepatotoxicity induced by arsenic, cadmium, chromium, copper, lead and mercury, prevents histological injury, lipid peroxidation and glutathione (GSH) depletion, maintains the liver antioxidant enzyme status and protects against mitochondrial dysfunction. The preventive effect of curcumin on the noxious effects induced by heavy metals has been attributed to its scavenging and chelating properties, and/or to the ability to induce the Nrf2/Keap1/ARE pathway. However, additional research is needed in order to propose curcumin as a potential protective agent against liver damage induced by heavy metals.

Meta-analysis of all-trans retinoic acid-linked arsenic trioxide treatment for acute promyelocytic leukemia

OBJECTIVES

To explore the combination therapy of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO, As2O3) on acute promyelocytic leukemia (APL).

METHODS

A meta-analysis of six studies was performed. Among 415 included cases, 165 cases were in the ATRA + ATO group, 129 cases in the ATRA-alone group, and 121 cases in the ATO-alone group. The complete remission (CR) rate and incidences of three groups were compared, respectively, between the therapies of ATRA + ATO with ATRA-alone, ATRA + ATO with ATO-alone, and ATRA with ATO.

RESULTS

The assessment results showed that ATRA + ATO therapy significantly improved the CR rate and decreased the incidences of cutaneous reaction compared with ATRA-alone (P < 0.05). However, incidence of liver injury was higher in the ATRA + ATO and ATO-alone groups than that in ATRA-alone group (P < 0.05). Difference in the complications between ATRA + ATO therapy and ATO-alone was not significant (P > 0.05).

CONCLUSIONS

In conclusion, we suggest low-dose ATRA and ATO combination therapy may be more effective for the treatment of APL.