二硫代氨基甲酸吡咯烷联合苦参碱对人肝癌裸鼠移植瘤生长的抑制作用

目的 探讨二硫代氨基甲酸吡咯烷(PDTC)抑制核因子-κ B(NF-κ B)活化后对苦参碱抑制人肝癌裸鼠移植瘤生长的影响.方法 建立人肝癌细胞HepG2裸鼠皮下移植瘤模型,随机分为对照组(灭菌等渗盐水)、苦参碱组(35 mg/kg)、PDTC组(120 mg/kg)和PDTC(120 mg/kg)+苦参碱(35 mg/kg)联合组,腹腔注射用药.绘制肿瘤生长曲线,测定肿瘤生长抑制率;TdT介导的dUTP缺口末端标记法检测肿瘤细胞凋亡情况;电泳迁移率变动分析法检测细胞核内NF-κB的活化水平;免疫组织化学法检测肿瘤组织bcl-2和bax蛋白表达水平;RT-PCR法检测肿瘤细胞NF-κB、bcl-2和bax的mRNA表达水平.多组间比较用SNK-q检验,单独效应比较采用LSD法,相关分析采用Pearson法进行分析.结果 PDTC增强了苦参碱对肿瘤增殖的抑制作用(P＜0.05);苦参碱在诱导肿瘤细胞凋亡的同时激活NF-κB;PDTC能显著抑制苦参碱诱导的NF-κB活化,NF-κB活性的灰度值由93.64±2.95降至65.78±5.65(F=124.754,P＜0.01),同时促进苦参碱诱导肿瘤细胞凋亡,细胞凋亡指数由55.9%±2.8%升高至74.3%±4.8%(P＜0.05).NF-κB的mRNA表达水平与bcl-2的mRNA表达水平呈正相关(r=0.983,P＜0.01).结论苦参碱诱导皮下移植瘤细胞凋亡的同时激活NF-κB;PDTC可通过抑制NF-κB的活化而下调bcl-2的表达,改变bcl-2与bax的比值,增强苦参碱诱导肿瘤细胞凋亡的作用.

Abstract：

Objective To investigate the relationship between activation of nuclear factor-κ-gene binding (NF-κ B) and apoptosis induced by matrine(MT) in transplanted tumor of human hepatocellular carcinoma in nude mouse. Methods Tumors were established by injection of hepatocellular carcinoma cell line HepG2 into the back of nude mice. The mice were divided randomly into four groups: Control group, MT group (35 mg/kg), PDTC group (120 mg/kg) and Combination group: PDTC+MT group (120 mg/kg+35 mg/kg), the reagents were injected peritoneally. The tumor growth curve of nude mice bearing transplanted tumor were observed and the inhibition ratios were evaluated. Apoptosis of carcinoma cells was analyzed by TUNEL. The DNA-bingding activity of NF-κ B was determined by electrophoretic mobility shift assay (EMSA). Expression of bcl-2 and bax in carcinoma tissue were detected by immunohistochemical method.NF-κ B mRNA, bcl-2 mRNA and bax mRNA in carcinoma tissue were detected by RT-PCR. Results Pyrrolidine dithiocarbamate (PDTC) could enhance the inhibition of matrine on carcinoma proliferation (P＜0.05). The apoptosis and activation of NF-κB in carcinoma cells could be induced by matrine. PDTC significantly suppressed NF-κ B activation induced by matrine in carcinoma cells from 93.64±2.95 to 65.78±5.65 (F=124.754, P＜0.01). Meanwhile, PDTC increased the apoptosis induced by matrine from 55.9%±2.8%to 74.3%±4.8% (P＜0.05).A positive correlation observed between the expressions of NF-κ B and of bcl2 (Pearson correlation coefficient=0.983,P＜0.01). Conclusions Matrine could induce apoptosis and activation of NF-κ B in transplanted tumor. PDTC could increase apoptosis in hepatocellular carcinoma cells might be due to the suppression of NF-κ B activation and the enhancement of bcl-2 expression.     

乙型肝炎病毒P22e蛋白经核因子-κB抑制HepG2细胞凋亡

目的 探讨核因子-κB(NF-κB)在乙型肝炎病毒P22e蛋白抑制HepG2细胞凋亡中的作用.方法 用含HBV P22e基因的重组pEGFP-C2HBVP22e质粒的肝癌细胞HepG2,以放线菌素-D(Act-D)、肿瘤坏死因子(TNF)α诱导该细胞凋亡,采用激光共聚焦显微镜、核蛋白电泳迁移率等技术,观察在HBV P22e抑制TNFα诱导HepG2EGFP-C2HBVP22e细胞的凋亡过程中NF-κB的核转移、活化等情况.用NF-κB抑制剂ALLN抑制其信号通路,检测以Act-D、TNFα诱导的HepG2、HepG2EGFP-C2HBVP22e细胞凋亡率的变化.对实验结果的数据分析用秩和检验和t检验. 结果激光共聚焦显微镜及电泳迁移率实验观察到HepG2EGFP-C2HBVP22e细胞在发生凋亡前后,有明显的NF-κB向核内迁移活化现象.NF-κB抑制剂ALLN可使以Act-D、TNF α诱导HepG2EGFP-C2HBVP22e细胞的凋亡率明显升高(6.19%±1.58%与39.99%±7.620/0,t=7.515,P<0.01).结论 在HBV P22e蛋白抑制肝癌细胞凋亡过程中,NF-κB信号途径起着重要作用.     

小干扰RNA抑制核因子-κB活化对HepG2细胞凋亡的影响

目的 探讨小干扰RNA(SiRNA)抑制核转录因子(NF)-κB活化对肝癌细胞凋亡的影响.方法 化学合成NF-κB siRNA和阴性对照siRNA,脂质体法转染HepG2细胞,用巢式RT-PCR和荧光定量PCR检测NF-κB mRNA表达情况;免疫组织化学法、酶联免疫吸附法、Western b10t检测NF-κB蛋白表达情况;用磷脂结合蛋白V-异硫氰酸荧光素法检测细胞凋亡,分析NF-κB表达抑制和细胞凋亡间关系.多个样本均数间的比较先行方差齐性检验,方差齐时行单因素方差分析;计数资料比较采用确切概率法分析.结果 NF-κBp65 mRNA在HepG2细胞相对表达量为1.13±0.03,在正常肝细胞L02为0.29±0.07,两者比较,t=27.02,P<0.05,差异有统计学意义.利用NF-κB siRNA干扰可下调NF-κB表达,且呈剂量、时间依赖;NF-κB siRNA转染HepG2细胞72h后,NF-κBmRNA和蛋白表达分别下降了93%和62%,抑制NF-κB表达使HepG2细胞凋亡增加85%. 结论 NF-κB在肝癌细胞中高表达,NF-κB SiRNA能特异性抑制其在肝癌细胞中活化并促进癌细胞凋亡发生.     

EGCG经NF-κB途径抑制肝癌HepG2细胞增殖的研究

目的 初步探讨EGCG抑制肝癌HepG2细胞增殖的作用机制.方法 通过绘制细胞生长曲线、平皿克隆和软琼脂集落形成实验观察EGCG对HepG2细胞增殖的抑制作用;Western blot检测NF-κB P65蛋白的表达.结果 细胞生长曲线、平皿克隆和软琼脂集落形成实验结果显示,EGCG可有效抑制HepG2细胞的增殖(n=3,P＜0.05).Western blot检测结果显示,EGCG处理后NF-κB P65蛋白表达降低.结论 EGCG通过抑制HepG2细胞中NF-κB P65蛋白表达发挥其对细胞增殖的抑制作用.     

重组腺病毒Ad-IкBαM在5-氟尿嘧啶诱导胃癌细胞凋亡中的作用

目的:研究重组腺病毒Ad-IκBαM对5-氟尿嘧啶(5-FU)诱导胃癌细胞凋亡的作用情况,进而研究胃癌细胞抵抗5-FU的机制.方法:培养胃癌SGC-7901细胞,感染重组腺病毒Ad-IκBαM的细胞为实验组,感染Ad-IκBα及非感染的空白对照为对照组,以5 mg/L5-FU加入上述各组细胞,采用EMSA法检测5-FU处理后各组细胞内NF-κB激活情况;应用MTT和TUNEL法分别检测5-FU对各组细胞诱导凋亡的情况.结果:5-FU作用于胃癌细胞可使细胞内NF-κB激活,感染Ad-IκBαM使NF-κB活性受到明显抑制.MTT法证明,5-FU作用后,感染Ad-IκBαM细胞的凋亡(56.36%±0.60%)较感染Ad-IκBα组(47.50%±1.42%)及未感染组(42.95%±1.27%)明显,各组间比较有统计学差异(P＜0.001);TUNEL法结果与MTT相符,感染Ad-IκBαM组的凋亡率为29.7%±2.5%,明显高于感染Ad-IκBα组(20.0%±2.6%)及未感染组(12.3%±1.1%)(P＜0.01).可见,感染Ad-IκBαM可明显提高5-FU诱导的细胞凋亡.结论:感染Ad-IκBαM可通过抑制胃癌细胞NF-κB的活性增强5-FU的诱导凋亡作用.     

蛋白激酶C/NF-κB在X线辐射诱导HepG2细胞凋亡中的作用

目的 探讨蛋白激酶C/核因子κB(NF-κB)在X线电离辐射诱导HepG2细胞凋亡中的作用.方法 分对照组、辐射组、PMA(蛋白激酶C激活剂)组、SP(蛋白激酶C抑制剂)组.流式细胞仪检测细胞凋亡率;EMSA 检测NF-κB的激活.免疫印迹法检测IκB的表达.结果 对照组、辐射组、PMA组、SP组细胞凋亡率分别为1.73%、20.90%、3.20%、40.57%.对照组的NF-κB微弱激活,辐射组NF-kB明显激活,并诱导了胞质内IκB的降解;PMA可增强NF-κB的激活,加强胞质内IκB的降解;SP减弱NF-κB的激活,抑制质内IκB降解.结论 蛋白激酶C可能参与了6 Gy X线辐射诱导的HepG2细胞凋亡的保护机制, 发挥抗凋亡作用,且可能是通过激活NF-κB来实现的.     

胰岛素抵抗肝癌细胞IGF-1R/NF-κB表达及多药耐药机制研究

目的 探讨胰岛素抵抗（IR）肝癌细胞胰岛素样生长因子1受体（IGF-1R）和核因子-κB（NF-κB）表达变化及多药耐药（MDR）发生机制。方法 采用高浓度胰岛素诱导人肝癌细胞（HepG2和HepG2.2.15）建立胰岛素抵抗（IR）细胞模型。采用Western blot 法检测胰岛素受体（InsR）、IGF-1R、NF-κB 和 P-糖蛋白（P-gp）表达变化。使用流式细胞仪（Annexin V-FITC法）检测阿霉素对细胞凋亡的影响。结果 分别用100 nmol/L 和 1 000 nmol/L 胰岛素培养 HepG2 和 HepG2.2.15 细胞 48 h,成功建立 IR 肝癌细胞模型;IR 肝癌细胞 IGF-1R、NF-κB、P-gp 表达上调,而InsR 表达下调;应用 25μg/mL 阿霉素作用细胞 24 h 后,IR-HepG2 细胞组凋亡率（31.1%±1.9%）显著低于HepG2 细胞组【（49.7%±2.2%）,P＜0.01】,IR-HepG2.2.15细胞凋亡率【（20.1±1.7） %】显著低于 HepG2.2.15 细胞【（33.8±1.8）%,P＜0.01】;HepG2.2.15 和 IR-HepG2.2.15 细胞凋亡率分别较 HepG2 和 IR-HepG2 细胞显著降低（P＜0.01）。结论 IGF-1R/NF-κB/P-gp 过表达可能介导 IR 肝癌细胞对阿霉素的多药耐药。     

还原型谷胱甘肽对多柔比星处理HepG2细胞株效果的影响

目的研究还原型谷胱甘肽(GSH)对多柔比星(DOX)处理HepG2细胞株增殖及凋亡的影响;探索核转录因子(NF)-κB p65、Bcl-2在DOX单药及联合GSH诱导HepG2细胞凋亡后的表达及其意义。方法实验分4组,空白组:培养液,对照组:培养液+HepG2细胞+RPMl l640培养基,DOX组:培养液+HepG2细胞+DOX,DOX+GSH组:培养液+HepG2细胞+DOX+GSH。MTT法检测HepG2细胞生长,流式细胞仪检测细胞早期凋亡率,实时荧光定量PCR法检测NF-κB p65 mRNA的表达,Western印迹检测NF-κB p65及Bcl-2的表达。结果 (1)DOX组和DOX+GSH组作用细胞24 h、48 h、72 h均能显著抑制HepG2细胞增殖,DOX组抑制率显著高于DOX+GSH组(P0.05),且抑制率具有时间和剂量依赖性。(2)对照组凋亡率为(0.733±0.153)%,DOX组凋亡率为(28.400±0.007)%,DOX+GSH组凋亡率为(15.500±0.006)%;DOX组、DOX+GSH组分别与对照组相比,差异有统计学意义(P0.01);DOX组与DOX+GSH组相比,差异有统计学意义(P0.01)。(3)两组在处理细胞24 h后,DOX+GSH组NF-κB p65mRNA表达显著高于DOX组(P0.05)。(4)DOX组NF-κB p65、Bcl-2表达较对照组增高,DOX+GSH组表达较DOX组表达增高。结论 GSH与DOX联合使用可导致DOX化疗效果下降,其机制可能是通过进一步上调NF-κB p65和Bcl-2的表达实现的。临床上使用DOX化疗的肿瘤患者应避免同时使用GSH。     

洛铂对肝癌HepG2细胞增殖和调亡的作用及机制

目的在体外细胞中研究洛铂对肝癌HepG2细胞在增殖、凋亡方面的作用及其机制。方法将HepG2细胞分为洛铂组(增殖实验:5、10、15μmol/L组;凋亡实验:10μmol/L;侵袭实验:4μg/ml)和对照组(不加药物)。利用CCK8法和流式细胞术分别检测2组HepG2细胞的增殖和凋亡情况。通过Western Blot初步检测2组细胞中增殖、凋亡相关蛋白NF-κB、Bcl-2、Bax、Bid、Puma、Caspase-3的表达变化。增殖实验采用双因素方差分析,凋亡实验采用χ2检验,侵袭实验采用t检验。结果在作用于细胞24、48、72 h后,对照组与实验组细胞生长增殖抑制率差异有统计学意义(F=273.5,P<0.01),同一时间不同浓度间、同一浓度不同时间差异均有统计学意义(F分别为1857、1365,P值均<0.01)。2组间细胞凋亡率比较差异有统计学意义(χ2=1821,P<0.001)。实验组HepG2细胞中穿透Transwell小室的细胞数少于对照组(21.30±2.74 vs 45.00±4.26,t=11.89,P<0.001)。洛铂组HepG2细胞Bcl-2表达水平下降,NF-κB、Bax、Puma、Caspase-3表达水平升高。结论洛铂可通过影响一系列增殖、凋亡蛋白发挥抑制肝癌细胞增殖及促进凋亡的作用,但细胞内信号通路复杂,需要进一步研究。     

厄贝沙坦通过核转录因子κB信号通路减轻高糖诱导的H9C2细胞炎症反应及凋亡的研究

目的探讨厄贝沙坦通过抑制核转录因子κB(NF-κB)的表达减轻高糖诱导的H9C2细胞炎症反应及凋亡。方法将H9C2细胞分为:对照(Con)组(5.5 mmol/L葡萄糖)、甘露醇(Man)组(5.5 mmol/L葡萄糖+27.5 mmol/L甘露醇)、二甲基亚砜(DMSO)组(5.5 mmol/L葡萄糖+1‰二甲基亚砜)、高糖(HG)组(33 mmol/L葡萄糖)、厄贝沙坦(Ir)组(33 mmol/L葡萄糖+1μmol/L厄贝沙坦),每组3个细胞。检测细胞增殖抑制率;IL-6、单核细胞趋化蛋白1(MCP-1)、TNF-α、Bax、Bcl-2 mRNA;核转录因子κB(NF-κB)、caspase-3蛋白表达及细胞凋亡率。结果 Ir组低于高糖诱导的Bax[(50.31±2.18)vs(61.96±4.08)]、IL-6[(7.67±1.53)vs(25.33±4.16)]、MCP-1[(26.67±6.11)vs(43.33±3.06)]、TNF-α[(35.33±3.06)vs(44.67±4.16)]、NF-κB[(2.19±0.52)vs(3.58±0.53)]及caspase-3[(2.28±0.10)vs(2.86±0.12)]表达及细胞凋亡[(10.73±1.78)vs(16.46±2.24)],差异均有统计学意义(P0.05);上调高糖抑制的Bcl-2[(0.62±0.04)vs(0.45±0.06)]的表达(P0.05)。结论厄贝沙坦通过NF-κB信号通路,可减轻高糖诱导的H9C2细胞炎症反应及凋亡。     

Nuclear factor-kappaB activation on the reactive oxygen species in acute necrotizing pancreatitic rats

AIM: To investigate the potential role of nuclear factor kappa-B (NF-KB) activation on the reactive oxygen species in rat acute necrotizing pancreatitis (ANP) and to assess the effect of pyrrolidine dithiocarbamate (PDTC, an inhibitor of NF-KB). METHODS: Rat ANP model was established by retrograde injection of 5% sodium taurocholate into biliopancreatic duct. Rats were randomly assigned to three groups (10 rats each): Control group, ANP group and PDTC group. At the 6th h of the model, the changes of the serum amylase, nitric oxide (NO), malondialdehyde (MDA), superoxide dismutase (SOD) and pancreatic morphological damage were observed. The expressions of inducible nitric oxide (iNOS) were observed by SP immunohistochemistry. And the expressions of NF-κB p65 subunit mRNA were observed by hybridization in situ. RESULTS: Serum amylase and NO level decreased significantly in ANP group as compared with PDTC administrated group [(7170.40±1308.63) U/L vs(4 074.10±1719.78) U/L, P<0.05], [(76.95±9.04) μmol/L vs(65.18±9.02)μmol/L, P<0.05] respectively. MDA in both ANP and PDTC group rose significantly over that in control group [(9.88±1.52) nmol/L, (8.60±1.41) nmol/L, vs(6.04±1.78) nmol/L, P<0.05], while there was no significant difference between them. SOD levels in both ANP and PDTC group underwent a significant decrease as compared with that in control t(3 214.59±297.74) NU/mL, (3 260.62±229.44) NU/mL, vs(3 977.80±309.09) NU/mL, P<0.05], but there was no significant difference between them. Though they were still higher than those in Control group, pancreas destruction was slighter in PDTC group, iNOS expression and NF-κB p65 subunit mRNA expression were lower in PDTC group as compared with ANP group. CONCLUSION: We conclude that correlation among NF-KB activation, serum amylase, reactive oxygen species level and tissue damage suggests a key role of NF-κB in the pathogenesis of ANP. Inhibition of NF-κB activation may reverse the pancreatic damage of rat ANP and the production of reactive oxygen species.     

Effect of nuclear factor kappa B on intercellular adhesion molecule-1 expression and neutrophil infiltration in lung injury induced by intestinal ischemia/reperfusion in rats

AIM:To investigate the role of nuclear factor kappa B(NF-κB) in the pathogenesis of lung injury induced byintestinal ischemia/reperfusion (I/R),and its effect onintercellular adhesion molecule-1 (ICAM-1) expressionand neutrophil infiltration.METHODS:Twenty-four Wistar rats weredivided randomly into control,I/R and pyrrolidinedithiocarbamate (PDTC) treatment groups,n=8 ineach.I/R group and PDTC treatment group receivedsuperior mysenteric artery (SMA) occluding for 1 h andreperfusion for 2 h.PDTC group was administrated withintraperitoneal injection of 2% 100 mg/kg PDTC 1 hbefore surgery.Lung histology and bronchia alveoluslung fluid (BALF) protein were assayed.Serum IL-6,lungmalondialdehyde (MDA) and myeloperoxidase (MPO) aswell as the expression level of NF-κB and ICAM-1 weremeasured.RESULTS:Lung injury induced by intestinal I/R,wascharacterized by edema,hemorrhage and neutrophilinfiltration as well as by the significant rising of BALFprotein.Compared to control group,the levels of serumIL-6 and lung MDA and MPO increased significantly in I/Rgroup (P=0.001).Strong positive expression of NF-κBp65 and ICAM-1 was observed.After the administrationof PDTC,the level of serum IL-6,lung MDA and MPOas well as NF-κB and ICAM-1 decreased significantly(P<0.05) when compared to I/R group. CONCLUSION:The activation of NF-kB plays animportant role in the pathogenesis of lung injury inducedby intestinal I/R through upregulating the neutrophilinfiltration and lung ICAM-1 expression.PDTC as aninhibitor of NF-kB can prevent lung injury induced byintestinal I/R through inhibiting the activity of NF-kB.     

一氧化氮-核因子κB信号通路在支气管哮喘患者T细胞功能表达中的作用

目的　探讨NO 核因子κB(NF κB)信号通路在哮喘患者T细胞细胞因子表达及细胞增殖、凋亡中的调控作用。方法　采用细胞原位杂交、电泳迁移率改变试验(EMSA)、免疫荧光、流式细胞术、双抗夹心ELISA、四甲基偶氮唑蓝微量比色法,观察不同浓度的硝普钠(SNP)及二硫代氨基甲酸吡咯烷(PDTC)对IL 4、IL 5、IFNγ表达及T细胞增殖、凋亡的影响。结果　(1)哮喘患者T细胞IL 4、IL 5mRNA和蛋白表达及细胞增殖均较对照组高,IFNγmRNA和蛋白表达及T细胞凋亡率均较对照组低(P<0 05); (2)低浓度的SNP能上调上述3种细胞因子表达,并使T细胞增殖反应增强、凋亡反应减弱;而中、高浓度的SNP却使上述3种细胞因子表达及细胞增殖率呈剂量依赖性地降低,并使T细胞凋亡率增加; ( 3 )PDTC可抑制10μmol/LSNP对IL 5和IFNγ表达的促进作用,增强1mmol/LSNP对IL 5和IFNγ表达的抑制作用,同时PDTC可减弱10μmol/LSNP对T细胞增殖反应的促进作用,增强1mmol/LSNP对T细胞增殖反应的抑制作用; (4)低浓度的SNP能明显增加NF κB活化细胞百分率及NF κB活性(P<0 05),而中、高浓度的SNP却显著减少NF κB活化细胞百分率及NF κB活性(P<0 05)。结论　哮喘患者T细胞细胞因子表达增多及细胞增殖反应的增强、凋亡反应的减弱与NF κB活化的异常增高有关。N     

Effect of Tetrandrine on LPS-induced NF-κB activation in isolated pancreatic acinar cells of rat

AIM: To investigate the effect of Tetrandrine (Tet) on LPS-induced NF-kappaB activation and cell injury in pancreatic acinar cells and to explore the mechanism of Tetrandrine preventing LPS-induced acinar cell injury. METHODS: Male rat pancreatic acinar cells were isolated by collagenase digestion, then exposed to LPS (10 mg/L), Tet (50 micromol/L, 100 micromol/L) or normal media. At different time point (30 min, 1 h, 4 h, 10 h) after treatment with the agents, cell viability was determined by MTT, the product and nuclear translocation of subunit p65 of NF-kappaB was visualized by immunofluorescence staining and nuclear protein was extracted to perform EMSA which was used to assay the NF-kappaB binding activity. RESULTS: LPS induced cell damage directly in a time dependent manner and Tet attenuated LPS-induced cell damage (50 micromol/L, P < 0.05; 100 micromol/L, P < 0.01). NF-kappaB p65 immunofluorescence staining in cytoplasm increased and began showing its nuclear translocation within 30 min and the peak was shown at 1 h of LPS 10 mg/L treatment. NF-kappaB DNA binding activity showed the same alteration pattern as p65 immunofluorescence staining. In Tet group, the immunofluorescence staining in cytoplasm and nuclear translocation of NF-kappaB were inhibited significantly. CONCLUSION: NF-kappaB activation is an important early event that may contribute to inflammatory responses and cell injury in pancreatic acinar cells. Tet possesses the protective effect on LPS-induced acinar cell injury by inhibiting NF-kappaB activation.     

去氢表雄酮通过Akt信号通路诱导肝癌细胞凋亡和细胞周期阻滞

目的 研究去氢表雄酮（DHEA）及其代谢物去氢表雄酮硫酸酯（DHEAs）对HepG2和HT-29细胞抑制增殖、促进凋亡及诱导细胞周期阻滞的作用。方法 应用MTT比色法检测不同浓度（1、10、50、100、200μmol／L）的DHEA或DHEAs与HepG2和HT-29细胞孵育8、24、48、72 h对两种细胞系的生长抑制作用;应用流式细胞术检测不同浓度的DHEA或DHEAs对细胞凋亡及细胞周期的变化;采用Western blot检测细胞内磷酸化Akt（Ser473,Thr308）蛋白的水平。结果 （1）不同浓度DHEA作用细胞24h时,HepG2的存活率24h时分别为92．7％±0．9%、84．7％±1．2％、62．4％±0．8％、49．5％±0．8％和50．7％±0．3％,HT-29细胞的存活率分别为92．5％±0.4％、89．5％±0．7％、80．5％±1．1％、67.5％±1.5％和70．6％±0．6％,与对照组相比,DHEA明显抑制HepG2和HT-29两种细胞的生长。在浓度为100μmol／L作用24 h时作用明显,而DHEAs对HepG2及HT-29细胞的增殖无明显影响。（2）100μmol／L的DHEA显著抑制两种细胞周期进程, HepG2细胞G0／G1期细胞比例显著升高,可以达到68．4％±2．0％,而对照组为48．6％±1．2％。HT-29细胞在100μmol／L时的G0／G1期的比率为90．3％±2．7％,而对照组仅为59．0％±1．2％,S及G2／M期细胞明显减少。（3）100μmol／L DHEA作用24 h时能显著诱导HepG2细胞凋亡（凋亡率为18．6％±2．2％）,而DHEAs却无此作用。（4）HepG2细胞在100μmol／L和200μmol／L DHEA作用24 h后,磷酸化Akt（Thr^308）、磷酸化Akt（Set^473）蛋白表达显著降低,这种作用在应用PI3K抑制剂和PI3K激活剂后分别被增强和消除。结论 DHEA对HepG2和HT-29两种肿瘤细胞系均具有较强的抗增殖作用。而对于不同的肿瘤细胞系,DHEA可能通过调节Akt的信号通路来诱导细胞凋亡,还可能通过阻滞细胞周期,使其阻滞在G0／G1期。DHEAs对细胞的生长没有明显的作用。     

Interferon-gamma inhibits hepatitis B virus-induced NF-kappaB activation through nuclear localization of NF-kappaB-inducing kinase

BACKGROUND & AIMS: Nuclear factor-kappaB (NF-kappaB) signaling pathway is an important regulating pathway in liver diseases, including hepatocellular carcinoma. In our study, immunohistochemical analysis showed that NF-kappaB-inducing kinase (NIK), an upstream kinase of IkappaB kinases, nuclear localization occurs only in liver tissues obtained from hepatitis B surface antigen (HBsAg)(+) patients but not in tissues from HBsAg(-) patients. The aim of the present study was to identify the inducer of NIK nuclear localization and determine whether the NIK nuclear localization affects the hepatitis B virus (HBV)-mediated NF-kappaB activation. METHODS: The experiments were performed on HepG2.2.15 cells and on HepG2 cells transfected with pHBV1.2x, a plasmid encoding all HBV messages, using NF-kappaB-dependent luciferase reporter gene assay, electrophoretic mobility shift assay, immunoblot analysis, and fluorescent microscopy analysis. RESULTS: HBV induced NIK-dependent NF-kappaB activation. However, interferon (IFN)-gamma induced NIK nuclear localization and inhibited NF-kappaB activation in HepG2.2.15 cells and in HepG2 cells transfected with pHBV1.2x. When NIK nuclear localization was inhibited by deletion of nuclear localization signal on NIK, IFN-gamma did not induce the NIK nuclear localization and did not inhibit NF-kappaB activation. CONCLUSIONS: IFN-gamma selectively inhibits HBV-mediated NF-kappaB activation. This inhibition is accomplished by NIK nuclear localization, which is a novel mechanism of NF-kappaB inhibition.     

Pro-apoptotic effects of tectorigenin on human hepatocellular carcinoma HepG2 cells

AIM: To investigate the effects of tectorigenin on human hepatocellular carcinoma (HCC) HepG2 cells.METHODS: Tectorigenin, one of the main components of rhizome of Iris tectorum, was prepared by simple methods, such as extraction, filtration, concentration, precipitation and recrystallization. HepG2 cells were incubated with tectorigenin at different concentrations, and their viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis was detected by morphological observation of nuclear change, agarose gel electrophoresis of DNA ladder, and flow cytometry with Hoechst 33342, Annexin V-EGFP and propidium iodide staining. Generation of reactive oxygen species was quantified using DCFH-DA. Intracellular Ca²⁺ was monitored by Fura 2-AM. Mitochondrial membrane potential was monitored using Rhodamine 123. Release of cytochrome c from mitochondria to cytosol was detected by Western blotting. Activities of caspase-3, -8 and -9 were investigated by Caspase Activity Assay Kit.RESULTS: The viability of HepG2 cells treated by tectorigenin decreased in a concentration- and time-dependent manner. The concentration that reduced the number of viable HepG2 cells by 50% (IC₅₀) after 12, 24 and 48 h of incubation was 35.72 mg/L, 21.19 mg/L and 11.06 mg/L, respectively. However, treatment with tectorigenin at 20 mg/L resulted in a very slight cytotoxicity to L02 cells after incubation for 12, 24 or 48 h. Tectorigenin at a concentration of 20 mg/L greatly inhibited the viability of HepG2 cells and induced the condensation of chromatin and fragmentation of nuclei. Tectorigenin induced apoptosis of HepG2 cells in a time- and dose-dependent manner. Compared with the viability rate, induction of apoptosis was the main mechanism of the anti-proliferation effect of tectorigenin in HepG2 cells. Furthermore, tectorigenin-induced apoptosis of HepG2 cells was associated with the generation of reactive oxygen species, increased intracellular [Ca²⁺]_i, loss of mitochondrial membrane potential, translocation of cytochrome c, and activation of caspase-9 and -3.CONCLUSION: Tectorigenin induces apoptosis of HepG2 cells mainly via mitochondrial-mediated pathway, and produces a slight cytotoxicity to L02 cells.     

In vivo suppressive effect of nudear factor-κB inhibitor on neutrophilic inflammation of grafts after orthotopic liver transplantation in rats

AIM. To investigate the effect of pyrrolidine dithiocarbamate (PDTC), a novel nuclear factor-κB (NF-κB) inhibitor, on expression of multiple inflammatory mediators and neutrophilic inflammation of cold preserved grafts after rat liver transplantation and its significance.METHODS: Orthotopic liver transplantation (OLT) was performed after 24 h of cold storage using University of Wisconsin solution with varied concentrations of PDTC. We determined the time course of NF-κB activation and expression of multiple inflammatory signals, such as tumor necrosis factor-α (TNF-α), cytokine-inducible neutrophil chemoattractant (CINC), and intercellular adhesion molecule-1(ICAM-1) by ELISA methods. Serum alanine aminotransferase (ALT), intrahepatic myeloperoxidase (MPO)/WBC (a measure of neutrophil accumulation) and Mac-1 expression (a measure of circulating neutrophil activity) were also evaluated.RESULTS: PDTC decreased NF-κB activation induced by prolonged cold preservation in a dose dependent manner (from 20 mmol/L to 60 mmol/L), diminished TNF-α, CINC,ICAM-1 proteins in the grafts, and reduced the expression f increases in plasma TNF-α levels induced by prolonged old preservation. Neutrophilic inflammation of the graft was significantly suppressed after preservation with PDTC (P&lt;0.05). The total neutrophil accumulation in PDTC (40 mmol/L) group (7.04&#177;0.97) was markedly reduced compared to control group (14.07&#177;1.31) (P&lt;0.05). Mac-1 expression was significantly reduced in PDTC (40 retool/L) group (181&#177;11.3%) compared with the control group (281&#177;13.2%) (P&lt;0.05) at 6 h after reperfusion. Furthermore,PDTC inhibited the increased serum ALT levels after liver transplantation.CONCLUSION: PDTC can inhibit B NF-κB activation and expression of the inflammatory mediators, which are associated with improved graft viability via inhibiting intrahepatic neutrophilic inflammation. Our study suggests that a therapeutic strategy directed at inhibition of NF-κB activation in the transplanted liver might be effective in reducing intrahepatic neutrophilic inflammation, and would be beneficial to cold preserved grafts,