Our group found that long-term low-dose exposure to hexavalent chromium [Cr(VI)] in L-02 hepatocytes resulted in premature senescence, which accompanied by the increased expression of Clusterin (CLU), but the functional role of CLU in premature senescence has never been explored. In the present study, the CLU overexpressed or silenced L-02 hepatocytes were established by lentiviral vector transfection. Cell viability assay, cell cycle analysis, western blotting, plate clone formation assay, and confocal microcopy were performed. The results indicated that Cr(VI)-induced premature senescence was associated with phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway inhibition, and high expression of CLU in the senescent cells exerted its functional role of promoting cell proliferation. CLU could complex with eukaryotic translation initiation factor 3 subunit I (EIF3I) and prevent its degradation, leading to the increase of AKT activity in Cr(VI)-exposed senescent hepatocytes. Blockage of the PI3K/AKT pathway with its inhibitor LY294002 eliminated the inhibitory effect of CLU on Cr(VI)-induced premature senescence. We concluded that high expression of CLU suppressed Cr(VI)-induced premature senescence through activation of PI3K/AKT pathway, which will provide the experimental basis for the study of Cr(VI)-induced liver cancer, especially for the elucidation of the mechanism of liver cancer cells escaping from senescence.

目的 探讨单次静脉注射和灌胃毒死蜱后,毒死蜱在家兔体内的毒代动力学过程.方法 分别以2和10 mg/kg·bw剂量给家兔静脉注射染毒,分别以100和500 mg/kg· bw剂量给家兔灌胃染毒,于给药后不同时间采集血液样本;应用气相色谱法测定各样本中毒死蜱及其特异性代谢产物的含量,用DAS 3.0软件计算毒代动力学参数.结果 毒死蜱经静脉染毒2 mg/kg·bw组非房室模型统计矩参数血浆中峰浓度为(1.83±0.43) mg/L;半衰期为(7.03+3.26)h;浓度曲线下面积为(0.53±0.19) mg/L×h.10 mg/kg组非房室模型统计矩参数血浆中峰浓度为(2.95±1.10) mg/L;半衰期为(10.91±2.21)h;浓度曲线下面积为(2.13±0.45) mg/L×h.毒死蜱经口染毒100 mg/kg组非房室模型统计矩参数血浆中峰浓度为(1.21±0.42)mg/L;半衰期为(13.58±11.18)h;浓度曲线下面积为(2.80±0.91) mg/L×h.500 mg/kg·bw组非房室模型统计矩参数血浆中峰浓度为(6.38±1.26) mg/L;半衰期为(22.07±7.73)h;浓度曲线下面积为(154.06±43.69)mg/L×h.结论 毒死蜱经静脉染毒在家兔体内的变化过程符合二室模型,经口染毒符合三室模型.获得了不同染毒方式毒死蜱在家兔体内的毒代动力学参数.

Retraction of ‘Cd induces G2/M cell cycle arrest by up-regulating miR-133b via directly targeting PPP2R2D in L02 hepatocytes’ by Yujing Zhang et al., Metallomics, 2018, 10, 1510–1523.

The mortality attributed to organophosphorus（OP） pesticide self-poisoning is an estimated 200,000 people ayear,largely in the Asia-Pacific region [1] According to the National Management Information System of Public Health Emergencies of China,the

Background/Aims: Hexavalent chromium [Cr(VI)] pollution has become a global concern for both ecosystems and human health. Our previous study revealed Cr(VI) could induce both apoptosis and autophagy in L-02 hepatocytes. Here, we sought to explore the underlying mechanism of Cr(VI)-induced autophagy and its exact role in cell death. Methods: Autophagy ultrastructure was observed under transmission electron microscope (TEM), autophagy flux was measured with double-tagged mCherry-green fluorescent protein (GFP)-microtubule-associated protein 1 light chain 3 (LC3) assay, long-lived protein degradation assay, and LC3II expression assay in the presence of lysosomal inhibitor, bafilomycin A1 (BafA1). Reactive oxygen species (ROS) level was determined using fluorescent probe dichloro-dihydrofluorescein diacetate (DCFH-DA). The expression levels of Beclin-1, LC3, p62/ SQSTM1, and AKT-mammalian target of rapamycin (mTOR) pathway-related molecules including phosphorylation (p)-AKT, AKT, p-mTOR, and mTOR were examined using real-time polymerase chain reaction (RT-PCR) and western blotting. Apoptosis was determined using Annexin V- fluorescein isothiocyanate (FITC)/propidium iodide (PI) staining. Results: Our results demonstrated Cr(VI) exposure activated autophagy in L-02 hepatocytes, as evidenced by the accumulation of autophagosomes, the increase of LC3-II and degradation of p62/ SQSTM1, and the enhanced overall degradation of proteins. We also confirmed Cr(VI)-induced LC3-II elevation mainly came from autophagy induction rather than lysosomal degradation impairment. ROS-AKT-mTOR pathway was associated with Cr(VI)-induced autophagy, and ROS scavenger N-acetylcysteine (NAC) pretreatment inhibited Cr(VI)-induced autophagy by alleviating the inhibition of the AKT-mTOR pathway. Autophagy inhibitors 3-methyladenine (3-MA) and chloroquine diphosphate (CDP) promoted Cr(VI)-induced apoptotic death. Conclusion: These findings indicated Cr(VI)-induced autophagy protected L-02 hepatocytes from apoptosis through the ROS-AKT-mTOR pathway.

Retraction of Cd induces G2/M cell cycle arrest by up-regulating miR-133b via directly targeting PPP2R2D in L02 hepatocytes' by Yujing Zhang et al., Metallomics, 2018, 10, 1510-1523.

环境内分泌干扰物(EDC)对人体和动物的多个组织器官具有潜在的危害,可诱导内分泌相关肿瘤、生长发育障碍和出生缺陷等疾病的发生.此外,肝也是EDC作用的主要靶器官.本文从常见EDC的肝毒性特点及分子机制等方面进行综述,如氧化应激、DNA损伤和细胞色素P450酶系功能异常等,为探讨EDC致肝疾病发生机制提供理论依据.

Previous research has shown that cadmium (Cd), which accumulates primarily in the liver and kidneys, could cause cell cycle arrest in various cell types. In the present study, the effect of Cd on the cell cycle progression of hepatocytes and the underlying mechanisms were investigated. Our results showed that Cd inhibited the growth and proliferation of L02 hepatocytes. Further study revealed that Cd significantly induced G2-phase cell cycle arrest accompanied by an overproduction of reactive oxygen species (ROS). Cd-induced G2-phase arrest could be prevented by inhibiting ROS with the use of antioxidant Trolox. Additionally, treatment with Cd induced an increase in the expression of miR-133b, which could be reversed with Trolox pretreatment. Moreover, miR-133b was shown to regulate PPP2R2D expression by binding to the 3'-untranslated region (UTR) of PPP2R2D mRNA. We also found that treatment with Cd decreased the expression of PPP2R2D, and inhibition of PPP2R2D expression by siRNA partially aggravated Cd-induced cell cycle arrest. By artificially increasing the expression of the protein phosphatase 2A-B55δ subunit (PP2A-B55δ, encoded by the PPP2R2D gene), we confirmed that PPP2R2D can be regulated by miR-133b in Cd-treated cells, and the G2-phase arrest effect could be suppressed by PP2A-B55δ. Collectively, these findings indicated that Cd increased ROS and induced the expression of miR-133b, which consequently inhibited the expression of PPP2R2D and led to G2-phase arrest in L02 hepatocytes. This study provides novel insights into the molecular mechanisms of Cd-induced cell cycle arrest.

BACKGROUD:Drinking water contamination with hexavalent chromium [Cr (VI)] has become one of the most serious public health problems, thus the investigation of Cr (VI)-induced hepatotoxicity has attracted much attention in recent years.METHODS:In the present study, by determining the indices of hepatotoxicity induced by Cr (VI), the source of accumulated reactive oxygen species (ROS), and the protective effect of the antioxidant Vitamin C (Vit C), we explored the mechanisms involved in Cr (VI)-induced hepatotoxicity in vitro and in vivo.RESULTS:We found Cr (VI) caused hepatotoxicity characterized by the alterations of several enzymatic and cytokine markers including aspartate aminotransferase (AST), alanine aminotransferase (ALT), interleukine-1β (IL-1β), and tumor necrosis factor-α (TNF-α), etc. ROS production after Cr (VI) exposure was origins from the inhibition of electron transfer chain (ETC) and antioxidant system. Vit C inhibited ROS accumulation thus protected against Cr (VI)-induced hepatotoxicity in L-02 hepatocytes and in the rat model.CONCLUSIONS:We concluded that ROS played a role in Cr (VI)-induced hepatotoxicity and Vit C exhibited protective effect. Our current data provides important clues for studying the mechanisms involved in Cr (VI)-induced liver injury, and may be of great help to develop therapeutic strategies for prevention and treatment of liver diseases involving ROS accumulation for occupational exposure population.

Hexavalent chromium (Cr(VI)) is a ubiquitous environmental pollutant, which poses a threat to human public health. Recent studies have shown that mitochondrial biogenesis can be activated by inflammatory and oxidative stress. However, whether mitochondrial biogenesis is involved in Cr(VI)-induced hepatotoxicity is unclear. Here, we demonstrated the induction of inflammatory response and oxidative stress, as indicated by upregulation of inflammatory factors and reactive oxygen species (ROS). Subsequently, we demonstrated that mitochondrial biogenesis, comprising the mitochondrial DNA copy number and mitochondrial mass, was significantly increased in HepG2 cells exposed to low concentrations of Cr(VI). Expression of genes related to mitochondrial function complex I and complex V was upregulated at low concentrations of Cr(VI). mRNA levels of antioxidant enzymes, including superoxide dismutase 1 and 2 (SOD1 and SOD2, respectively), kech like ECH associate protein 1 (KEAP1) and nuclear respiratory factor 2 (NRF-2), were also upregulated. Consistent with the above results, mRNA and protein levels of key transcriptional regulators of mitochondrial biogenesis such as the peroxisome-proliferator-activated receptor γ coactivator-1α (PGC-1α), NRF-1 and mitochondrial transcription factor A (TFAM) were increased by low concentrations of Cr(VI) in HepG2 cells. Moreover, we found that PGC-1α and NRF-1 tended to translocate into the nucleus. The expression of genes potentially involved in mitochondrial biogenesis pathways, including mRNA level of silent information regulator-1 (SIRT1), forkhead box class-O (FOXO1), threonine kinase 1 (AKT1), and cAMP response element-binding protein (CREB1), was also upregulated. In contrast, mitochondrial biogenesis was inhibited and the expression of its regulatory factors and antioxidants was downregulated at high and cytotoxic concentrations of Cr(VI) in HepG2 cells. It is believed that pretreatment with α-tocopherol could be acting against the mitochondrial biogenesis imbalance induced by Cr(VI). In conclusion, our study suggests that the homeostasis of mitochondrial biogenesis may be an important cellular compensatory mechanism against Cr(VI)-induced toxicity and a promising detoxification target.

TNKS1BP1 is a member of the poly(ADP-ribose) polymerase (PARP) superfamily. Our previous studies have demonstrated that TNKS1BP1 plays an important role in DNA damage response. But whether and how TNKS1BP1 associates with cancer is still not clear. Here, we found that TNKS1BP1 was upregulated in human lung adenocarcinoma (LAC) tissues, and was associated with poor overall survival (OS) in LAC patients. Dysregulation of TNKS1BP1 affected the sensitivity of A549 cells to several DNA damage agents including cisplatin, bleomycin, and ionizing radiation. Mechanically, overexpression of TNKS1BP1 increased the accumulation of S phase cells, which was accompanied by a decrease in M phase cells. More importantly, we found TNKS1BP1 regulated genome stability, mainly through affecting the homologous recombination pathway of DNA double-strand breaks by inhibiting the RAD51 foci formation. Overall, our study indicates that, in LAC, aberrant expressions of TNKS1BP1 are common events, and overexpression of TNKS1BP1 might affect outcomes of cancer patients to chemotherapy and radiotherapy.

化学物诱导细胞凋亡的途径除了外源性和内源性途径外,内质网在细胞凋亡过程中也扮演着与上述2种途径不同的角色[1].钙离子(Ca2+)作为细胞内重要的第二信使,在细胞的各种生理及病理活动中发挥着重要作用[2].内质网作为细胞内Ca2+储存的主要场所,当细胞受到外源性化合物作用时,内质网内Ca2+代谢失衡,功能紊乱,导致内质网应激(Endoplasmic reticulum stress,ERS)的发生进而诱导细胞凋亡[3].本文主要就ERS的机制和信号通路、ERS与外源性化合物诱导的细胞凋亡以及Ca2+与ERS诱导的细胞凋亡等进行简要概述,为探讨外源性化合物的毒作用机制提供新的方向.

Hexavalent chromium could result in cell malfunctions. Intracellular Ca2+ ([Ca2+]i) content and VDAC1 expression are both important features related to cell survial. This study aimed to explore the mechanism of cell injury induced by Cr(VI) and tentatively offer clues to repairing this cell damage using [Ca2+]i and VDAC1. L-02 hepatocytes were treated with Cr(VI)/BAPTA, and the levels of [Ca2+]i and cell injury associated with Cr(VI) were determined in addition to the effect of BAPTA. The expression of VDAC1 in Cr(VI)-induced cells was evaluated. The results showed a dose-dependent elevation of the level of VDAC1 and the mRNA level of the VDAC1 biogenesis-related gene Sam50. BAPTA could ameliorate less severe damage induced by 4μM Cr(VI) via reducing VDAC1 and Sam50. Additionally, cell injury caused by less than 4μM Cr(VI) could be ameliorated by VDAC1 knockdown. Taken together, the findings of this study suggest that inhibition of intracellular Ca2± overload could protect cells from damage and that VDAC1 plays a considerable role in Cr(VI)-induced liver injury.

The occupational and environmental toxicant hexavalent chromium [Cr(VI)] can cause severe damage to the liver; however, the exact mechanisms associated with its toxicity have not been thoroughly demonstrated. In the present study, the underlying mechanisms of Cr(VI)-induced hepatotoxicity were investigated. Our results showed that Cr(VI) inhibited the growth and proliferation of L-02 hepatocytes. Further study revealed that Cr(VI) significantly induced S-phase cell cycle arrest and apoptosis accompanying with the overproduction of reactive oxygen species (ROS). Cr(VI)-induced apoptosis could be prevented by inhibiting ROS with N-acetyl-l-cysteine (NAC). Additionally, our data showed that Cr(VI)-induced endoplasmic reticulum (ER) stress and mitochondrial dysfunction were concentration- and time-dependent. Moreover, inhibition of C/EBA homologous protein (CHOP) expression by siRNA partially prevented Cr(VI)-induced cell apoptosis, mitochondrial dysfunction and ROS generation. We also found that Cr(VI) treatment inhibited the PI3K/Akt pathway in a concentration- and time-dependent manner. After using IGF-1 (50ng/mL), the specific agonist of the PI3K/AKT signaling pathway, the facilitating effects of Cr(VI) were depressed. This finding demonstrated the relationship between the PI3K/Akt pathway, ER stress and mitochondrial dysfunction. Collectively, these findings indicated that Cr(VI) increased ROS production. Increased ROS production may account for inhibition of the PI3K/Akt pathway and lead to ER stress and mitochondrial dysfunction, which consequently induces apoptosis in L-02 hepatocytes. This study provides novel insights into the molecular mechanisms of Cr(VI)-induced cytotoxicity.

The goal of the present study was to elucidate the in vitro cytotoxicity of Roundup and to reveal the possible related mechanisms in L-02 hepatocytes. By detecting reactive oxygen species (ROS) production, glutathione (GSH)/superoxide dismutase (SOD) levels, mitochondrial permeability transition pore (PTP) open rate, apoptosis-inducing factor (AIF) release, intracellular Ca2+ concentration, and alanine aminotransferease (ALT)/aspartate aminotransferase (AST) leakage, we determined that Roundup induced anti-oxidant system inhibition, mitochondria damage, DNA damage, membrane integrity and permeability changes, and apoptosis in L-02 hepatocytes. By revealing the mechanistic insights of Roundup-induced cytotoxicity, our results are valuable for the design of preventive and therapeutic strategies for the occupational population exposed to Roundup and other pesticides.

Chromium is a widely used chemical,which demonstrated the acute and chronic toxicity,including neurotoxicity,genotoxicity,carcinogenicity and immunotoxicity.We aimed to provide experimental evidence for the prevention and cure of the hexavalent chromium (Cr(Ⅵ))-induced hazard.Voltage-dependent anion channel-1 (VDAC1) is an essential player in mammalian apoptosis by regulating mitochondrial membrane permeability.VDAC1 is a key functional target of the BCL-2 protein family,and BAX and BAK can interact with VDAC1 and form a large pore,through which apoptogenic proteins such as cytochrome C released.But the molecular mechanism of VDAC1 in cell apoptosis is still not clear.We established the VDAC1 stably knocked-down cell lines L02-VDAC1-1 and shVDAC1-2 through sustained expression of shRNA against VDAC1 and then detected the survival rate,the apoptosis rate,reactive oxygen species (ROS) production,mitochondrial function and the contents of apoptosis inducing factor.The result showed that the survival rate of the shVDAC is higher than that of L02 and the apoptosis rate is decreased.The result concerning ROS production showed that knocking down of VDAC1 can prevent Cr(Ⅵ)-induced ROS accumulation compared with L02.The inner MPTP and the contents of cytochrome C (cyt C) and apoptosis inducing factors were significantly increased in response to Cr(Ⅵ) stimuli in L02,but these phenomena did not occur in shVDAC1.The results in this study demonstrated that VDAC1 mediates Cr(Ⅵ)-induced L02 hepatocytes apoptosis,and the inhibition of VDAC 1 expression could reduce the adverse effects induced by Cr(Ⅵ) exposure.

To investigate the toxic mechanism of hexavalent chromium Cr(VI) and search for an antidote for Cr(VI)-induced cytotoxicity, a study of mitochondrial dysfunction induced by Cr(VI) and cell survival by recovering mitochondrial function was performed. In the present study, we found that the gene expression of electron transfer flavoprotein dehydrogenase (ETFDH) was strongly downregulated by Cr(VI) exposure. The levels of coenzyme 10 (CoQ10) and mitochondrial biogenesis presented by mitochondrial mass and mitochondrial DNA copy number were also significantly reduced after Cr(VI) exposure. The subsequent, Cr(VI)-induced mitochondrial damage and apoptosis were characterized by reactive oxygen species (ROS) accumulation, caspase-3 and caspase-9 activation, decreased superoxide dismutase (SOD) and ATP production, increased methane dicarboxylic aldehyde (MDA) content, mitochondrial membrane depolarization and mitochondrial permeability transition pore (MPTP) opening, increased Ca2+ levels, Cyt c release, decreased Bcl-2 expression, and significantly elevated Bax expression. The Cr(VI)-induced deleterious changes were attenuated by pretreatment with CoQ10 in L-02 hepatocytes. These data suggest that Cr(VI) induces CoQ10 deficiency in L-02 hepatocytes, indicating that this deficiency may be a biomarker of mitochondrial dysfunction in Cr(VI) poisoning and that exogenous administration of CoQ10 may restore mitochondrial function and protect the liver from Cr(VI) exposure.

Inducible nitric oxide synthase (NOS2) and endothelial nitric oxide synthase (NOS3) gene play important roles in the susceptibility to type 2 diabetes mellitus (T2DM). The present study aims to detect the potential association of NOS2 and NOS3 gene polymorphisms with the susceptibility toT2DM and diabetic nephropathy (DN) in the Chinese Han population. Four hundred and ninety T2DM patients and 485 healthy controls were enrolled in this case-control study. The genotypes of NOS2 and NOS3 gene polymorphisms were analyzed by the polymerase chain reaction (PCR)-ligase detection reaction (LDR) method. Our data demonstrated that the NOS2 rs2779248 and NOS2 rs1137933 genetic polymorphisms were significantly associated with the increased susceptibility to T2DM in the heterozygote comparison, dominant model, and allele contrast; and NOS3 rs3918188 genetic polymorphism was significantly associated with the increased susceptibility to T2DM in the homozygote comparison and recessive model. The allele-C and genotype-TC of NOS2 rs2779248, allele-A and genotype-GA of NOS2 rs1137933 and genotype-AA of NOS3 rs3918188 genetic polymorphisms might be the risk factors for increasing the susceptibility to T2DM. And a significant haplotype effect of NOS2 rs10459953/C- rs1137933/G- rs2779248/T was found between T2DM cases and controls. Moreover, NOS3 rs1800783 polymorphism was significantly associated with the increased susceptibility to DN in the heterozygote comparison, recessive model and allele contrast. At last, a positive correlation of family history of diabetes with NOS3 rs11771443 polymorphism was found in DN. These preliminary findings indicate that the NOS2 rs2779248, NOS2 rs1137933, and NOS3 rs3918188 genetic polymorphisms are potentially related to the susceptibility to T2DM, and the rs1800783 polymorphism might be considered as genetic risk factors for diabetic nephropathy, and family history of diabetes was closely associated with rs11771443 polymorphism in DN, and the genetic variants might be used as molecular markers for evaluating the risk of T2DM and diabetic nephropathy. © 2016 IUBMB Life, 68(7):516-525, 2016.

Hexavalent Chromium [Cr(VI)], which can be found of various uses in industries such as metallurgy and textile dying, can cause a number of human disease including inflammation and cancer. Unlike previous research that focused on Cr(VI)-induced oxidative damage and apoptosis, this study placed emphasis on premature senescence that can be induced by low-dose and long-term Cr(VI) exposure. We found Cr(VI) induced premature senescence in L-02 hepatocytes, as confirmed by increase in senescence associated-β-galactosidase (SA-β-Gal) activity. Cr(VI) stabilized p53 through phosphorylation at Ser15 and increased expression of p53-transcriptional target p21. Mechanism study revealed Cr(VI) targeted and inhibited mitochondrial respiratory chain complex (MRCC) I and II to enhance reactive oxygen species (ROS) production. By applying antioxidant Trolox, we also confirmed that ROS mediated p53 activation. A tetracycline-inducible lentiviral expression system containing shRNA to p53 was used to knockout p53. We found p53 could inhibit pro-survival genes B-cell lymphoma-2 (Bcl-2), myeloid leukemia-1 (Mcl-1) and S phase related cell cycle proteins cyclin-dependent kinase 2 (CDK2), Cyclin E to induce premature senescence, and the functional role of ROS in Cr(VI)-induced premature senescence is depend on p53. The results suggest that Cr(VI) has a role in premature senescence by promoting ROS-dependent p53 activation in L-02 hepatocytes.

Hexavalent chromium [Cr(vi)] is a potent cytotoxin and carcinogen. In recent years, drinking water contamination with Cr(vi) has become a worldwide problem of significant public health importance, thus much attention has been paid to the investigation of Cr(vi)-induced hepatotoxicity. The concentration of intracellular calcium ions ([Ca2+]i) was found to be increased after Cr(vi) exposure, but the exact underlying mechanisms involved in the Ca2+ homeostasis imbalance remain poorly characterized. In the present study, by utilizing the antagonist of store-operated calcium channels (SOCCs) 2-aminoethoxydiphenyl borate (2-APB), small interfering RNA against stromal interaction molecule 1 (si-STIM1) and antioxidant N-acetylcysteine (NAC), we found that Cr(vi) induces [Ca2+]i increase, cell viability loss and transaminase (AST/ALT) leakage, and that these could be suppressed by both 2-APB and si-STIM1. NAC significantly alleviated Cr(vi)-induced up-regulation of STIM1, phosphorylated-extracellular-signal-regulated kinases 1 and 2 (p-ERK1/2), ERK1/2 and nuclear factor κB (NF-κB). By utilizing the ERK inhibitor U0126 and the NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC), we confirmed that STIM1 can be regulated by ERK and NF-κB. Thus we concluded that STIM1 plays a role in the Cr(vi)-induced [Ca2+]i increase and cell injury. Our current data provide new insights into the mechanisms of STIM1 function in Cr(vi)-induced hepatotoxicity, and may provide experimental clues for the prevention and treatment of liver diseases in the occupational population exposed to Cr(vi).