二氯乙腈诱导HepG2细胞凋亡及机制研究

目的 研究二氯乙腈(DCAN)对人肝肿瘤HepG2细胞凋亡的作用及其机制。 方法 用二甲基亚砜(DMSO)溶解DCAN,以DMSO处理的HepG2细胞作为对照组, 50和800 μmol/L 的DCAN处理的HepG2细胞作为处理组,采用Cell Counting Kit-8(CCK-8)试剂盒检测细胞活力,流式细胞术(FCM)检测细胞周期分布情况,Annexin V-FITC/PI双标记法测定细胞凋亡率;荧光测定法检测HepG2细胞内天冬氨酸特异性半胱氨酸蛋白酶-3(caspase-3)活性。 结果 DCAN处理浓度和处理时间存在交互效应(P<0.001),与对照组比较,DCAN可明显抑制HepG2增殖,呈现时间和剂量效应(P<0.05);与对照组比较,800 μmol/L DCAN处理组G₀/G₁期比例明显减少,G₂/M期细胞比例明显增加;DCAN诱导的HepG2细胞凋亡随着浓度的增加而增加,呈剂量-效应关系,回归方程为=0.031x+5[决定系数(R²)=0.915,F=64.782,P<0.001];DCAN诱导的HepG2细胞内caspase-3酶活性随着处理浓度的增加而增加,呈剂量-效应关系,回归方程为=0.001 6x+1(R²=1.000,F=21 266.064,P<0.001)。 结论 DCAN可抑制HepG2细胞增殖并诱导细胞凋亡,其机制可能与G₂/M期细胞阻滞、抑制RNA和蛋白质的合成并激活细胞内caspase-3凋亡途径有关。     

Toxicity of Sodium Sulfite to HepG2 Hepatocytes

目的 观察食品添加剂亚硫酸钠对人肝肿瘤细胞( HepG2)的细胞毒性作用和脂肪变作用.方法向HepG2细胞悬液中分别加入终浓度为0(阴性对照)～ 10 mmol/L亚硫酸钠溶液染毒24、48和72 h,并设空白对照(无细胞)组和阳性对照组(含1％Tritonx -100的DMEM),每组6个复孔.采用乳酸脱氢酶(LDH)活力测定法检测肝细胞膜的通透性变化,采用CCK-8法检测肝细胞的活性改变,采用油红O染色法观察肝细胞内脂肪沉积情况.结果 与阴性对照组相比,仅10 mmol/L亚硫酸钠染毒24h后HepG2细胞培养上清中LDH活力的释放率增加(P＜0.05);而各剂量亚硫酸钠染毒48和72 h后HepG2细胞培养上清中LDH活力的释放率无显著变化.与阴性对照组相比,各剂量亚硫酸钠染毒24、48、72 h后(除0.039 mmol/L染毒72 h外)HepG2细胞的存活率均显著下降(P＜0.05),且细胞存活率随着亚硫酸钠染毒剂量的升高而降低.染毒24、48 h后,部分亚硫酸钠染毒组HepG2细胞内出现了极少量的脂滴,而阴性对照组却未发现;染毒72 h后,10 mmol/L亚硫酸钠染毒组出现明显脂滴.结论 一定剂量的亚硫酸钠染毒可增加HepG2细胞膜的通透性,对肝细胞活性有明显的抑制作用,并且可引起肝细胞内甘油三酯的蓄积.     

亚硫酸钠对HepG2细胞毒性的实验研究

目的观察食品添加剂亚硫酸钠对人肝肿瘤细胞(HepG2)的细胞毒性作用和脂肪变作用。方法向HepG2细胞悬液中分别加入终浓度为0(阴性对照)～10 mmol/L亚硫酸钠溶液染毒24、48和72 h,并设空白对照(无细胞)组和阳性对照组(含1%Tritonx-100的DMEM),每组6个复孔。采用乳酸脱氢酶(LDH)活力测定法检测肝细胞膜的通透性变化,采用CCK-8法检测肝细胞的活性改变,采用油红O染色法观察肝细胞内脂肪沉积情况。结果与阴性对照组相比,仅10 mmol/L亚硫酸钠染毒24 h后HepG2细胞培养上清中LDH活力的释放率增加(P<0.05);而各剂量亚硫酸钠染毒48和72 h后HepG2细胞培养上清中LDH活力的释放率无显著变化。与阴性对照组相比,各剂量亚硫酸钠染毒24、48、72 h后(除0.039 mmol/L染毒72 h外)HepG2细胞的存活率均显著下降(P<0.05),且细胞存活率随着亚硫酸钠染毒剂量的升高而降低。染毒24、48 h后,部分亚硫酸钠染毒组HepG2细胞内出现了极少量的脂滴,而阴性对照组却未发现;染毒72 h后,10 mmol/L亚硫酸钠染毒组出现明显脂滴。结论一定剂量的亚硫酸钠染毒可增加HepG2细胞膜的通透性,对肝细胞活性有明显的抑制作用,并且可引起肝细胞内甘油三酯的蓄积。     

胸腺嘧啶核苷诱导肝癌HepG2细胞同步化

目的探讨胸腺嘧啶核苷（TdR）诱导肝癌HepG2细胞同步化的方法。方法于对数生长期的HepG2细胞中加入含终浓度为2．5mmoL／L的TdR培养28h后，PBS洗除TdR，加入新鲜血清培养基，此时记为0时刻，分别继续培养0、2、3、4、5、6、7、8、9、12、18、24、28h，收集细胞，同时实验设立对照组，采用流式细胞术检测细胞周期。结果分别于去除TdR后培养4、8、24h获得78．1％的S期细胞、67．2％的G2／M期细胞、86．3％的G1期细胞。结论终浓度为2．5mmoL／L的TdR处理肝癌HepG2细胞28h，再以新鲜培养基培养不同时间，可以获得同步化效果较好的S、G2／M和G1期细胞。     

Lipid synthesis and secretion in HepG2 cells is not affected by ACTH

Apolipoprotein B (apoB) containing lipoproteins, i.e. VLDL, LDL and Lp(a), are consequently lowered by ACTH treatment in humans. This is also seen as reduced plasma apoB by 20-30% and total cholesterol by 30-40%, mostly accounted for by a decrease in LDL-cholesterol. Studies in hepatic cell line (HepG2) cells showed that apoB mRNA expression is reduced in response to ACTH incubation and is followed by a reduced apoB secretion, which may hypothesize that ACTH lowering apoB containing lipoproteins in humans may be mediated by the inhibition of hepatic apoB synthesis. This was recently confirmed in vivo in a human postprandial study, where ACTH reduced transient apoB48 elevation from the small intestine, however, the exogenic lipid turnover seemed unimpaired. In the present study we investigated if lipid synthesis and/or secretion in HepG2 cells were also affected by pharmacological levels of ACTH to accompany the reduced apoB output. HepG2 cells were incubated with radiolabelled precursors ([¹⁴C]acetate and [³H]glycerol) either before or during ACTH stimuli. Cellular and secreted lipids were extracted with chloroform:methanol and separated by the thin layer chromatography (TLC), and [¹⁴C]labelled cholesterol and cholesteryl ester and [³H]labelled triglycerides and phospholipids were quantitated by the liquid scintillation counting. It demonstrated that ACTH administration did not result in any significant change in neither synthesis nor secretion of the studied lipids, this regardless of presence or absence of oleic acid, which is known to stabilize apoB and enhance apoB production. The present study suggests that ACTH lowers plasma lipids in humans mainly mediated by the inhibition of apoB synthesis and did not via the reduced lipid synthesis.     

Subcellular localization of soybean 7S globulin in HepG2 cells and LDL receptor up-regulation by its alpha' constituent subunit

The aims of this work were to monitor the subcellular localization of soybean 7S globulin in HepG2 cells and determine its interaction with cell protein components, by using laser-induced fluorescence capillary electrophoresis (LIF-CE). Furthermore, we evaluated in the same cell line the involvement of the alpha' constituent subunit from 7S globulin in the modulation of LDL catabolism. The results indicated a main fluorescein isothiocyanate-tagged 7S globulin (FITC-7S) component in the cytosolic fraction, that was not present in the nuclear compartment. The electrophoretic mobility of this tagged component suggested either a dissociation of the 7S oligomer or its partial intracellular degradation. Interactions of soybean 7S globulin with FITC-thioredoxin 1 and FITC-cyclophilin B, HepG2 cell membrane proteins, were demonstrated in in vitro assays. In a separate experiment with HepG2 cells, the ability of the alpha' subunit purified from soybean 7S globulin to modulate the activity of the LDL receptors was evaluated by tracking the uptake and degradation of labeled LDL. The up-regulation of LDL receptors by the alpha' subunit, as further confirmed by a LDL receptor promoter assay, was significantly greater than that found in the control cells. In conclusion, this study, while confirming our previous indirect evidence of the key role of alpha' subunit on the cell cholesterol homeostasis, reveals a potentially interesting association of soybean 7S globulin with proteins, such as thioredoxin 1 and cyclophilin B, that are involved in cell protection against oxidative stress.     

赛莱西布对肝癌HepG2细胞增殖与凋亡影响

目的探讨选择性环氧合酶-2（cox-2）抑制剂赛莱西布（celecoxib）对人肝癌细胞株HepG2细胞增殖、凋亡的影响及其可能的作用机制。方法用不同浓度的赛来西布处理HepG2细胞，分别应用四甲基偶氮噻唑蓝试验、DNA梯度电泳法、放射免疫法检测赛亚西布对HepG2细胞增殖和凋亡及其COX-2活性的影响；应用免疫印迹法和比色法检测赛莱西布对HepG2细胞胱氨酸蛋白酶3（clasepase-3）蛋白质的表达及活性的影响。结果12．5，25，50μmol／L的赛莱西布作用于HepG2细胞后，HepG2细胞增殖受抑制，与对照组比较，差异有统计学意义（P〈0．01）；赛莱西布干预组HepG2细胞DNA明显降解，可见细胞凋亡特征性梯状DNA条带；干预组HepG2细胞caspase3蛋白表达及活性均明显升高。与对照组比较，差异均有统计学意义（P〈0．01）；赛莱西布明显抑制HepG2细胞cox-2活性。与对照组比较，差异有统计学意义（P〈0．01）。结论赛莱西布可通过cox-2通路和easpase3通路抑制HepG2细胞增殖并诱导其凋亡。     

黄芪多糖抑制HepG2细胞增殖及可能机制研究

目的 研究黄芪多糖对HepG2细胞增殖的作用及可能机制。 方法 用不同浓度(100、200和400 μg/ml)的黄芪多糖(astragalus polysaccharide,APS)处理HepG2细胞,采用MTT法检测细胞增殖,采用Western blot检测细胞内糖原合成酶激酶3β(glycogen synthase kinase 3β,GSK3β)的表达。 结果 APS100组、APS200组及APS400组HepG2细胞第1~7 d吸光度和GSK3β蛋白质表达均显著低于对照组(P<0.05);APS100组和APS400组HepG2细胞D1~D7吸光度和GSK3β蛋白质表达差异无统计学意义(P>0.05),但均显著高于APS200组(P<0.05)。 结论 黄芪多糖可显著抑制HepG2细胞增殖,其机制可能与抑制糖原合成酶激酶3β表达有关,其中200 μg/ml抑制作用最强。     

干扰素-α诱导HepG2 2.2.15细胞APOBEC3G的表达及其机制

目的 探讨干扰素(IFN)-α刺激HepG2 2.2.15细胞后,对载脂蛋白B mRNA编辑酶催化多肽样3G(apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3G,APOBEC3G)表达的影响,以及初步探讨Ja-nus激酶-信号传导和转录激活子(JAK-STAT)信号通道是否参与APOBEC3G基因转录调控.方法 对HepG22.2.15细胞给予不同剂量(0、1、101、102、103、104 U/mL)IFN-α刺激8 h时,以及10U/mL IFN-α刺激2、4、6、8、10、12 h时,收集细胞或培养上清液.应用实时荧光定量逆转录聚合酶链反应(RT-PCR)及Western blot检测HepG2 2.2.15细胞APOBEC3G、STAT-1 mRNA及蛋白的表达水平.应用酶联免疫吸附试验(ELISA)检测细胞培养上清液中乙型肝炎表面抗原与e抗原(HBsAg与HBeAg)水平,应用实时荧光定量PCP及RT-PCR分别检测上清液中HBV DNA水平以及细胞中HBV mRNA水平.结果 无IFN-α(O U/mL)刺激时,HepG2 2.2.15细胞APOBEC3G表达水平很低.随着IFN-α浓度的升高,APOBEC3G mRNA及蛋白水平逐步升高,IFN-α浓度为104U/mL时,APOBEC3G表达量最高,并且STAT-1分子mRNA及蛋白的表达量亦逐步升高,与APOBEC3G表达量呈现平行相关.随着IFN-α刺激时间的延长,APOBEC3G表达量明显升高,8 h时达到最高,其后逐渐下降.104 U/mL-α刺激8 h时,HepG2 2.2.15细胞培养上清液中HBsAg、HBeAg、HBV DNA及细胞中HBV mR-NA水平均明显低于无IFN-α刺激的HepG2 2.2.15细胞.结论 IFN-α能诱导HepG2 2.2.15细胞表达APO-BEC3G,在一定范围内,APOBEC3G的表达与IFN-α的剂量、作用时间呈正相关;IFN-α诱导APOBEC3G的表达可能是其发挥抗病毒作用的机制之一;IFN-α是否经JAK-STAT信号通道刺激APOBEC3G的表达,二者之间的关系及其机制尚待进一步研究.     

Suppression of apolipoprotein B secretion from HepG2 cells by glucosyl hesperidin

Our previous study has shown that a soluble hesperidin derivative, glucosyl hesperidin (G-hesperidin), preferentially lowers serum triglyceride (TG) level in hypertriglyceridemic subjects through the improvement of very low-density lipoprotein (VLDL) metabolic abnormality. G-Hesperidin has also been found to decrease an elevated serum apolipoprotein B (apo B) level in the hypertriglyceridemic subjects, suggesting a possibility that this compound suppresses excess VLDL secretion in the liver. In the present study, to gain a better understanding of possible mechanisms by which G-hesperidin lowers serum TG, we examined whether this derivative affects apo B secretion from HepG2 human hepatoma cells, a model of hepatic VLDL secretion. As a result, G-hesperidin significantly reduced apo B secretion from the oleate-stimulated HepG2 cells. Furthermore, G-hesperidin significantly suppressed apo B secretion only in the oleate-stimulated cells and failed to act on the cells incubated without oleate. In the oleate-stimulated cells, G-hesperidin significantly decreased cellular cholesteryl ester (CE), although it had no effect on cellular TG or free cholesterol amounts. Moreover, the oleate-stimulated cells had a decrease in cellular apo B amounts by G-hesperidin exposure. These findings indicate that G-hesperidin down-regulates the assembly of apo B-containing lipoproteins via the reduction of CE synthesis augmented with oleate and results in suppressing excess apo B secretion from the cells. This effect is speculated to be associated with the improvement of VLDL metabolic abnormality in hypertriglyceridemic subjects and considered as a mechanism of lowering serum TG.     

Youngia denticulata protects against oxidative damage induced by tert-butylhydroperoxide in HepG2 cells

Improvement of liver function is one of the most popular commercial health claims of functional foods in Asian countries, including Korea. After examining the potential of several traditional Korean wild vegetables for enhancing liver function, we found that Youngia denticulata Kitam. has strong hepatoprotective effects against oxidative stress induced by tert-butylhydroperoxide (t-BHP). We are the first to report that the extract and ethyl acetate fractions of Y. denticulata have radical scavenging activities and inhibit oxidative stress-induced cell death and DNA damage in HepG2 cells. The extract and ethyl acetate fractions significantly decreased cellular reactive oxygen species production and apoptosis induced by t-BHP in HepG2 cells. In addition, they prevented the depletion of cellular glutathione, which is an important defense molecule against oxidizing xenobiotics. Chlorogenic acid and 3,5-dicaffeoylquinic acid were found to be major active components responsible for the activity of Y. denticulata and could serve as marker compounds for standardization. These data suggest that Y. denticulata could be promoted as a potential antioxidative functional food candidate, particularly for hepatoprotection against oxidative stress.     

干扰素 α诱导HepG2 2.2.15细胞APOBEC3G的表达及其机制

目的探讨干扰素（IFN）-α刺激HepG2 2．2．15细胞后,对载脂蛋白BmRNA编辑酶催化多肽样3G（apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3G,APOBEC3G）表达的影响,以及初步探讨Janus激酶-信号传导和转录激活子OAK—STAT）信号通道是否参与APOBEC3G基因转录调控。方法对HepG2 2．2．15细胞给予不同剂量（0、1、10^1、10^2、10^3、10^4 U／mL）IFN-α刺激8h时,以及10^3 U／mL IFN-α刺激2、4、6、8、10、12h时,收集细胞或培养上清液。应用实时荧光定量逆转录聚合酶链反应（RT-PCR）及Western blot检测HepG22．2．15细胞APOBEC3G、STAT-1 mRNA及蛋白的表达水平。应用酶联免疫吸附试验（ELISA）检测细胞培养上清液中乙型肝炎表面抗原与e抗原（HBsAg与HBeAg）水平,应用实时荧光定量PCR及RT-PCR分别检测上清液中HBVDNA水平以及细胞中HBVmRNA水平。结果无IFN-α（0 U／mL）刺激时,HepGa2．2．15细胞APOBEC3G表达水平很低。随着IFN-a浓度的升高,APOBEC3GmRNA及蛋白水平逐步升高,IFN-α浓度为10^4 U／mL时,APOBEC3G表达量最高,并且STAT-1分子mRNA及蛋白的表达量亦逐步升高,与APOBEC3G表达量呈现平行相关。随着IFN-a刺激时间的延长,APOBEC3G表达量明显升高,8h时达到最高,其后逐渐下降。10^4 U／mL IFN-α刺激8h时,HepG2 2．2．15细胞培养上清液中HBsAg、HBeAg、HBVDNA及细胞中HBVmR-NA水平均明显低于无IFN-α刺激的HepG22．2．15细胞。结论WN-a能诱导HepG22．2．15细胞表达APO—BEC3G,在一定范围内,APOBEC3G的表达与IFN—d的剂量、作用时间呈正相关;IFN-α诱导APOBEC3G的表达可能是其发挥抗病毒作用的机制之一;IFN-α是否经JAK-STAT信号通道刺激APOBEC3G的表达,二者之间的关系及其机制尚待进一步研究。     

硒诱导HepG2细胞凋亡与活性氧的关系

目的探讨亚硒酸钠(Na2SeO3)诱导细胞凋亡的可能作用机制。方法用0、2.5、5、10和20μmol/L的Na2SeO3以及加有N-乙酰基-L-半胱氨酸(NAC)的Na2SeO3(10μmol/L)处理HepG2。用四甲基偶氮唑盐(MTT)比色法测定细胞活性;流式细胞仪测细胞内活性氧(ROS)的水平以及细胞凋亡情况。结果5、10和20μmol/LNa2SeO3作用于HepG21h即引起ROS增加,12h后HepG2细胞活性降低,24h后细胞早期凋亡以及晚期凋亡/坏死率均增加,与对照组相比差异有显著性(P<0.05);抗氧化剂NAC有效抑制了ROS的增加,并增加了细胞活性,降低了细胞凋亡率,与未加NAC的Na2SeO3组(10μmol/L)相比差异有显著性(P<0.05)。结论一定浓度的亚硒酸钠使HepG2细胞活性下降,促进了细胞凋亡,ROS的增加在其中发挥了作用。     

四溴双酚A对HepG2细胞的毒性作用及其剂量-反应关系评估

目的研究不同剂量四溴双酚A对HepG2细胞的毒性并评估其剂量-反应关系。方法以不同质量浓度的TBBPA染毒HepG2细胞,采用光学显微镜观察细胞形态,MTS法检测细胞存活率,LDH检测试剂盒检测细胞LDH漏出率,NOAEL和BMD法评估其剂量-反应关系。结果TBBPA能引起HepG2细胞形态变化和存活率降低,24hTBBPA处理的HepG2细胞形态随TBBPA质量浓度升高,逐渐萎缩变圆;HepG2细胞存活率与TBBPA处理呈质量浓度-效应关系和时间-效应关系,其12、24和48h的IC50分别为33．82、27．36和17．73μmol／L;TBBPA能导致HepG2细胞的细胞膜损伤,12、24和48hTBBPA处理的HepG2细胞LDH漏出率与TBBPA有质量浓度-效应关系;选择TBBPA暴露24h对HepG2细胞的抑制率为健康效应终点,其NOAEL、LOAEL、BMDL10和BMD10分别为10、15、9．45和10．34μmol／L。结论TBBPA对HepG2细胞具有明显的细胞毒性,其基准剂量值为9．45μmol／L。     

S-propyl cysteine reduces the secretion of apolipoprotein B100 and triacylglycerol by HepG2 cells

A number of sulfur-containing amino acids and peptides are found in allium plants such as onion and garlic that have physiologic functions. In HepG2 cells, S-propyl cysteine decreased the secretion of apolipoprotein B100. The compound reduced the secretion of newly synthesized triacylglycerol and cholesterols from radiolabeled acetate. We associated the decrease of apolipoprotein B100 secretion to the length of the acyl-chain of the sulfur-containing amino acids. The present study suggests that foods containing S-propyl cysteine including onions have beneficial effects.     

Exploratory Data Analysis of Cell and Mitochondrial High-Fat,High-Sugar Toxicity on Human HepG2 Cells

Non-alcoholic steatohepatitis (NASH), one of the deleterious stages of non-alcoholic fatty liver disease, remains a significant cause of liver-related morbidity and mortality worldwide. In the current work, we used an exploratory data analysis to investigate time-dependent cellular and mitochondrial effects of different supra-physiological fatty acids (FA) overload strategies, in the presence or absence of fructose (F), on human hepatoma-derived HepG2 cells. We measured intracellular neutral lipid content and reactive oxygen species (ROS) levels, mitochondrial respiration and morphology, and caspases activity and cell death. FA-treatments induced a time-dependent increase in neutral lipid content, which was paralleled by an increase in ROS. Fructose, by itself, did not increase intracellular lipid content nor aggravated the effects of palmitic acid (PA) or free fatty acids mixture (FFA), although it led to an up-expression of hepatic fructokinase. Instead, F decreased mitochondrial phospholipid content, as well as OXPHOS subunits levels. Increased lipid accumulation and ROS in FA-treatments preceded mitochondrial dysfunction, comprising altered mitochondrial membrane potential (ΔΨm) and morphology, and decreased oxygen consumption rates, especially with PA. Consequently, supra-physiological PA alone or combined with F prompted the activation of caspase pathways leading to a time-dependent decrease in cell viability. Exploratory data analysis methods support this conclusion by clearly identifying the effects of FA treatments. In fact, unsupervised learning algorithms created homogeneous and cohesive clusters, with a clear separation between PA and FFA treated samples to identify a minimal subset of critical mitochondrial markers in order to attain a feasible model to predict cell death in NAFLD or for high throughput screening of possible therapeutic agents, with particular focus in measuring mitochondrial function.     

Ambient particulate matter on DNA damage in HepG2 cells

Ambient particulate matter (PM) has been reported to be associated with increased respiratory, cardiovascular, and malignant lung diseases. The aim of the present study was to investigate the variability of the DNA-damage induced by thoracic particles (PM( 10)) sampled in different locations and seasons (2006) in Dalian, China, in human hepatoma G2 (HepG2) cells. Significant differences in percentage of tail DNA induced by the extractable organic matter of PM(10) were revealed between summer and winter seasons and among monitoring sites in single cell gel electrophoresis (SCGE) assay. The percentage of tail DNA in HepG2 cells significantly increased in a dose-dependent manner after exposure to 7.5 and 30 μg/mL extractable organic matter of PM(10) for 1 hour. In order to clarify the underlying mechanisms, we evaluated the level of reactive oxygen species (ROS) production with the 2, 7-dichloro-fluorescein diacetate (DCFH-DA) assay. Significantly increased level of ROS was observed in HepG2 cells at higher concentrations (15 and 30 μg/mL). Significantly increased levels of 8-hydroxydeoxyguanosine (8-OHdG) were also shown in HepG2 cells. In this study, the accumulation of nuclear factor kappa B (NF-κB) p65 protein induced by the extractable organic matter of PM(10) was detected by western blotting in HepG2 cells, and the protein expression of NF-κB p65 significantly increased after the treatment with 30 μg/mL extractable organic matter of PM(10) for 24 hours. These results indicate that the extractable organic matter of PM(10) causes DNA strand breaks in HepG2 cells, and significant differences in percentage of tail DNA in dependence on locality and season are revealed. The extractable organic matter of PM(10) exerts DNA damage effects in HepG2 cells, probably through oxidative DNA damage induced by intracellular ROS, increase of 8-OHdG formation, and protein expression of NF-κB p65.     

镉暴露对HepG2细胞NRF2信号通路影响

目的 探讨镉暴露对HepG2细胞转录因子NF-E2相关因子2（NRF2）信号通路的影响。方法 采用甲臢比色法测定CdCl₂（0、1、2.5、5、10、25、50、100、200 μmol/L）处理24 h后,HepG2细胞活力变化;应用蛋白免疫印迹法检测CdCl₂（1、2、5、10、20 μmol/L）处理细胞6 h后,NRF2蛋白水平;采用RT-qPCR方法检测10 μmol/L CdCl₂处理细胞2、4、6、12、24 h后,GCLC、GCLM、HO1 和 AKR1C1 mRNA水平变化,检测CdCl₂（1、2、5、10、20 μmol/L）处理细胞6 h后,GCLC、GCLM、HO1和AKR1C1 mRNA水平变化。结果 HepG2细胞活力随镉处理剂量升高而降低（P<0.05）;与对照组（0.60±0.01）比较, 1、2、5、10、20 μmol/L镉处理组HepG2细胞NRF2蛋白表达水平[分别为（0.65±0.01）、（1.37±0.04）、（1.94±0.05）、（2.24±0.07）、（2.22±0.05）]均明显升高（P<0.05）;与对照组比较,镉处理6 h时,HepG2细胞内GCLC、GCLM、HO1和AKR1C1 mRNA水平[分别为（45.76±7.04）、（114.21±5.23）、（59.52±1.50）、（674.13±27.12）]明显升高（P<0.05）;与对照组比较,5 μmol/L镉处理组HepG2细胞内GCLC和GCLM mRNA水平[分别为（24.77±2.16）、（29.93±0.67）]升高,2 μmol/L镉处理组HepG2细胞内HO1和AKR1C1 mRNA水平[分别（28.55±2.02）、（186.32±12.63）]升高（P<0.05）。结论 镉暴露能激活HepG2细胞系中NRF2信号通路。     

Effect of chromium on apolipoprotein A-I expression in HepG2 cells

OBJECTIVE: Chromium is a key micronutrient required for lipid and carbohydrate metabolism. Some but not all clinical trials have associated use of chromium supplements with improved insulin sensitivity and lipid profile including increased high-density lipoprotein cholesterol levels. METHODS: Because apolipoprotein A-I (apoA-I) is the principal protein of high-density lipoprotein, the molecular pathways underlying chromium-related changes in apoA-I expression were studied in a human hepatoma cell line (HepG2) transfected with full-length apoA-I promoter attached to the reporter chloramphenicol acetyl transferase gene. RESULTS: Exposure of these cells to different concentrations of chromium chloride (0, 0.5, 1.0, and 3.0 mM) resulted in a dose-dependent decrease in apoA-I promoter activity (chloramphenicol acetyl transferase activity expressed as a percentage of an internal control was 99.4 +/- 7.2% in control cells versus 87.6 +/- 5.0%, 73.4 +/- 2.3%, and 36.6 +/- 3.9%, respectively, P < 0.01). Chromium chloride at 10 mM concentration was toxic and caused death in a large number of cells. Treating HepG2 cells with other minerals known to have insulin-sensitizing effects such as magnesium (1 mM), zinc (0.2 mM), and vanadyl sulfate (0.1 mM) significantly reduced apoA-I promoter activity in the presence and absence of 100 microU/mL of insulin. Northern blot analyses showed that the apoA-I mRNA content of cells treated with 0.2 mM of chromium chloride relative to G3PDH mRNA was not significantly increased compared with controls (0.652 +/- 0.122 versus 0.745 +/- 0.143, the ratio of apoA-I to glyceraldehyde 3-phosphate dehydrogenase (G3PDH) mRNA in control and chromium-treated cells, respectively). Western blot analyses of proteins secreted in culture media indicated that neither chromium treatment of the HepG2 cells (858.0 +/- 151.4 arbitrary units) nor treatment with magnesium (1323.3 +/- 175.7) or vanadium (1102 +/- 78.7) significantly altered apoA-I concentrations compared with controls (1061.7 +/- 114.7). However treatment of HepG2 cells with 0.2 mM of zinc significantly reduced apoA-I concentrations (291.0 +/- 29.2 versus 1061.7 +/- 114.7; P < 0.001). CONCLUSIONS: Supraphysiologic concentrations of chromium and other minerals with known insulin-sensitizing activity may reduce apoA-I promoter activity in cultured cells. Whether similar changes may occur in vivo remains to be shown. However, these observations do not support the use of pharmacologic amounts of chromium supplementation to enhance the cardioprotective lipid profile.