Molecular mechanisms of methylmercury-induced cell death in human HepG2 cells

Methylmercury (MeHg) has been suggested to exert cytotoxicity through multiple mechanisms, but the precise biochemical machinery has not been fully defined. This study was aimed at investigating the time-course (0–24 h) effect of 2 mg/L MeHg on cell death in human HepG2 cells.     

吡格列酮对HepG2细胞增殖和凋亡的影响及机制研究

目的观察吡格列酮对体外培养的HepG2细胞增殖和凋亡的影响,并探讨其是否通过PPARγ依赖途径发挥上述药理作用。方法将不同浓度的吡格列酮作用于体外培养HepG2细胞,以MTT比色法检测HepG2细胞增殖情况,以3H-TdR参入实验检测细胞DNA合成速率,采用RT-PCR和Western blot检测PPARγmRNA和蛋白的表达,以流式细胞术检测细胞凋亡和细胞周期;同时观察PPARγ特异性拮抗剂GW9662和(或)瞬时转染pSG5-PPARγ真核表达质粒对吡格列酮细胞增殖作用的影响;并将PPARγ小干扰RNA(pGCsi-PPARγ)表达质粒稳定转染HepG2细胞,观察PPARγ沉默后吡格列酮对HepG2细胞增殖作用的影响。结果吡格列酮作用于HepG2细胞后,导致HepG2细胞的增殖受到抑制、DNA合成速率减慢,并诱导细胞凋亡,呈一定的剂量依赖关系;在此过程中,G0/G1期细胞比例明显增加,S期细胞比例明显减少,但PPARγmRNA和蛋白的表达没有变化;GW9662部分拮抗吡格列酮的增殖抑制作用,但转染pSG5-PPARγ真核表达质粒可以逆转GW9662的作用;吡格列酮在高浓度(20μmol.L-1)时对pGCsi-PPARγ表达质粒稳定转染的HepG2细胞仍表现出增殖抑制作用。结论吡格列酮能够抑制HepG2细胞的增殖并诱导凋亡,具有潜在的抗瘤作用,这种作用与其诱导细胞G0/G1期的停滞有关,PPARγ依赖和非依赖途径参与上述过程。     

腺苷体外对人肝癌HepG2细胞凋亡的诱导作用及其作用机制

目的研究腺苷及其代谢途径对人肝癌HepG2细胞凋亡的诱导作用及其机制。方法将腺苷2.0mmol.L-1作用于HepG2细胞24和48h,采用流式细胞术(FCM)测定细胞周期及凋亡率;观察腺苷膜转运体抑制剂双嘧达莫、腺苷脱氨酶抑制剂红-9-(2-羟基-3-壬烷基)腺嘌呤(EHNA)和腺苷激酶抑制剂5′-氨基5′-脱氧腺苷(AMDA)对腺苷抑制细胞存活的影响,应用MTT法测定细胞存活率;应用Western蛋白印迹法检测P53和Bcl-2蛋白的表达。结果腺苷与HepG2细胞作用24和48h,HepG2细胞出现特征性的亚二倍体凋亡峰,细胞凋亡百分率分别由对照组的(1.2±0.4)%和(4.1±1.6)%增加到(24.3±4.8)%和(38.6±7.4)%,细胞周期阻滞于G0/G1期。腺苷与HepG2细胞作用24h明显抑制细胞存活,P53表达明显增强,Bcl-2表达降低。预先分别给予双嘧达莫,AMDA和AMDA+双嘧达莫处理后,各处理组HepG2细胞存活率较腺苷组升高,细胞凋亡百分率和P53表达降低,Bcl-2表达无明显变化;EHNA预处理组细胞存活率、细胞凋亡百分率、P53和Bcl-2表达与腺苷组比较均无明显变化。结论腺苷可诱导HepG2细胞凋亡,腺苷在胞内可能通过腺苷激酶而不是通过转氨酶的代谢途径参与诱导细胞凋亡的过程。腺苷对HepG2细胞凋亡的诱导作用还可能与其增加P53蛋白表达有关。     

大黄素诱导人肝癌HepG2细胞线粒体凋亡作用研究

目的 研究大黄素对人肝癌HepG2细胞线粒体凋亡的影响。方法 培养人肝癌HepG2细胞,与5、10、20、40、60、80、100 μmol/L的大黄素作用24、48 h,MTS法检测细胞增殖;40、80、160 μmol/L大黄素作用HepG2细胞24 h,AO/EB双荧光染色法观察细胞凋亡的形态学改变;Annexin V/PI染色经流式细胞仪检测细胞凋亡;分光光度法检测caspase 3活性;ATP试剂盒检测细胞ATP含量,不同荧光探针加载后流式细胞仪测定大黄素对HepG2细胞内活性氧（ROS）含量、Ca²⁺浓度、线粒体膜电位（MMP）变化的影响。结果 大黄素抑制HepG2细胞生长,且呈时间、浓度相关性,半数抑制浓度（IC₅₀）为（77.42±1.25）μmol/L;随着大黄素浓度升高,AO/EB双染观察到细胞核浓缩、碎裂、凋亡小体等凋亡形态;与对照组比较,大黄素40、80、160 μmol/L作用于HepG2细胞24 h后细胞凋亡率显著增加,caspase 3活性显著增强,ROS水平、Ca²⁺浓度明显增加（P<0.05、0.01、0.001）,80、160 μmol/L组线粒体膜电位明显降低,ATP含量显著下降（P<0.05、0.01、0.001）。结论 大黄素造成HepG2细胞内ROS堆积,ATP合成功能障碍,线粒体膜电位明显下降,进而诱导线粒体通透转运孔开放,导致钙离子和细胞色素C外流,活化caspase蛋白家族,导致细胞凋亡。     

Molecular mechanisms of deguelin-induced apoptosis in transformed human bronchial epithelial cells

Increasing evidence has demonstrated that the phosphatidylinositol-3 kinase (PI3K)/Akt signaling pathway plays an important role in cell proliferation, apoptosis, angiogenesis, adhesion, invasion, and migration, functions that are critical to cancer cell survival and metastasis. Increased expression of activated Akt has been observed in the early stages of tobacco-induced lung carcinogenesis. Moreover, blocking the PI3K/Akt pathway specifically inhibits the proliferation of non-small cell lung cancer (NSCLC) cells, indicating that the PI3K/Akt pathway is a potential target for chemoprevention and therapy in lung cancer. The aim of this work is to study the lung cancer chemopreventive potential of PI3K/Akt inhibitors using an in vitro lung carcinogenesis model. We found that genetic or pharmacologic approaches targeting the PI3K/Akt pathway inhibited the proliferation of premalignant and malignant human bronchial epithelial (HBE) cells. After screening several natural products to identify a potential lung cancer chemopreventive agent, we have found that deguelin, a rotenoid isolated from Mundulea sericea (Leguminosae), specifically inhibits the growth of transformed HBE and NSCLC cells by inducing cell-cycle arrest in the G2/M phase and apoptosis, with no detectable toxic effects on normal HBE cells, most likely due to the agent's ability to inhibit PI3K/Akt-mediated signaling pathways. The specific sensitivity of premalignant and malignant HBE and NSCLC cells to deguelin suggests that this drug could be clinically useful for chemoprevention in early-stage lung carcinogenesis and for therapy in confirmed lung cancer.     

Molecular mechanisms involved in adenosine-induced endothelial cell barrier enhancement

Extracellular adenosine is a physiologically relevant agonist released by various sources, including endothelial cells (EC) and activated platelets, with complex effects mediated via activation of P1 purinergic receptors. Adenosine-induced EC production of glutathione peroxidase1 and nitric oxide is recognized, and an anti-inflammatory mechanism has been described. Effects of extracellular adenosine on the pulmonary EC barrier function and vascular permeability, however, remain poorly characterized. In this study, we demonstrated the adenosine-induced rapid dose-dependent barrier enhancement in human pulmonary artery EC (HPAEC) as measured by an increase in transendothelial electrical resistance (TER). We have shown that HPAEC express only A2A and A2B adenosine receptors. Pharmacological and siRNA depletion studies indicate that A2A, but not A2B receptor activation is required for the adenosine-induced TER increase. Depletion of Gαs with a specific siRNA significantly attenuated the adenosine-induced TER response in HPAEC. In contrast, depletion of either Gαq or Gαi2 did not affect the adenosine-induced TER increase. This suggests that the adenosine-induced TER increase is cAMP-dependent. The adenosine-induced barrier enhancement effects were associated with a rearrangement of the EC F-actin component of the cytoskeleton, enhanced cell-surface presentation of cell–cell junctional protein VE-cadherin and an involvement of Myosin-light-chain phosphatase (MLCP). Our results suggest, for the first time, that adenosine regulates the EC barrier function via A2A receptors followed by Gαs engagement and is associated with cytoskeletal activation.     

Enhancement of esculetin on Taxol-induced apoptosis in human hepatoma HepG2 cells

The potential use of low dose chemotherapy has been appealing since lower dosages are more attainable during cancer therapy and cause less toxicity in patients. Combination therapy of Taxol, a promising frontline chemotherapy agent, with natural anti-tumor agents that are considerably less toxic with a capability of activating additional apoptotic signals or inhibiting survival signals may provide a rational molecular basis for novel chemotherapeutic strategies. Esculetin, a well-known lipoxygenase inhibitor, showed an inhibitory effect on the cell cycle progression of HL-60 cells in our previous study. In this report, the effects of a concomitant administration of esculetin and Taxol were investigated in human hepatoma HepG2 cells. Firstly, esculetin alone could exert an antiproliferation effect together with an inhibitory effect on the activation of ERKs and p38 MAPK. As compared to the treatment with Taxol only, a co-administration with esculetin and Taxol could result in a further enhancement of apoptosis as revealed by DNA fragmentation assay and Annexin-V-based assay. Meanwhile, immunoblotting analysis also showed that the co-administration of esculetin and Taxol could increase the expression of Bax and the cytosolic release of cytochrome C and enhance the expression of Fas and Fas ligand while the activation of caspase-8 and caspase-3 was also increased. Finally, the ERK cascade was proven to be involved in the enhancement of esculetin on the Taxol-induced apoptosis.     

蜂毒素对人肝癌HepG2细胞增殖和凋亡的影响及其部分机制研究

目的研究蜂毒素对人肝癌HepG2细胞增殖和凋亡的影响,并探讨其作用和HDAC2及Hedgehog信号通路的关系。方法给予不同浓度蜂毒素,四甲基偶氮唑盐(MTT)法检测HepG2细胞的增殖变化,Hoechst33258染色和流式细胞术检测HepG2细胞凋亡变化;qRT-PCR检测SHH、PTCH1、SMO、Gli1、HDAC2 mRNA的表达;Western blot检测SHH、PTCH1、SMO、Gli1、HDAC2蛋白的表达。结果不同浓度的蜂毒素在作用48 h后,能明显抑制Hep G2细胞的增殖,促进其凋亡;Hedgehog信号通路中SHH、PTCH1、SMO、Gli1 mRNA及蛋白水平均明显降低,并与蜂毒素浓度呈负相关。同时检测到细胞内HDAC2 mRNA及蛋白水平均降低,与蜂毒素剂量呈负相关。结论蜂毒素可明显抑制人肝癌Hep G2细胞增殖,促进其凋亡,其作用与抑制HDAC2,下调Hedgehog信号通路密切相关。     

马钱子碱经JNK-Fas途径诱导人肝癌HepG2细胞的凋亡

目的探讨马钱子碱诱导人肝癌HepG2细胞凋亡的机制。方法通过CCK-8法检测马钱子碱对HepG2细胞的生长抑制作用,应用流式细胞术检测马钱子碱对HepG2细胞凋亡的影响以及Ca^(2+)的含量、激光共聚焦法观察Ca^(2+)的形态学分布情况、实时荧光定量聚合酶链反应(PCR)法检测基因的表达情况。结果马钱子碱可以有效抑制人肝癌HepG2细胞的生长,在一定范围内,随着时间的推移和浓度的增加,抑制率和凋亡率明显增加。马钱子碱作用于HepG2细胞后引起MKK7、JNK、Fas、FADD基因的变化,并最终引起Ca^(2+)的释放导致细胞溶解。结论马钱子碱对HepG2细胞有抑制生长的作用,并能诱导HepG2细胞发生凋亡。此过程通过JNKFas通路作用,最终引起细胞内Ca^(2+)的变化,诱导细胞发生凋亡。     

Induction of mitochondria-dependent apoptosis in HepG2 human hepatocellular carcinoma cells by timosaponin A-III

Timosaponin A-III (TSA-III), a saponin isolated from the rhizome of Anemarrhena asphodeloides, exhibits potent cytotoxicity and has the potential to be developed as an anticancer agent. However, the molecular mechanism underlying the anticancer activity of TSA-III has not been fully elucidated. In this study, the apoptotic effects of TSA-III were investigated in HepG2 cells. Treatment with TSA-III significantly inhibited cell growth in a concentration- and time-dependent manner by inducing apoptosis in HepG2 cells. This induction was associated with increased fluorescence intensity of Annexin V-FITC, activation of caspases, and altered expression of inhibitor of apoptosis protein (IAP) family members. In addition, TSA-III mediated mitochondrial dysfunction with the release of HtrA2/Omi, Smac/Diablo, and cytochrome c. These findings suggest that TSA-III induces mitochondria-mediated and caspase-dependent apoptosis in HepG2 cells by altering expression of the IAP family. Thus, TSA-III could possibly be used to treat other types of cancer with similar pathologic mechanisms.     

Drug toxicity mechanisms in human hepatoma HepG2 cells: cyclosporin A and tamoxifen

1. Mechanisms of drug toxicity operating in human HepG2 hepatoma cells have been assessed using cyclosporin A (CsA) and tamoxifen as examples.

2. Either 150 μM CsA or 50 μM tamoxifen caused approximately 50% loss of HepG2 cell viability. α-Tocopherol (32 μM) almost completely prevented cell death due to either CsA or tamoxifen. Tamoxifen stimulated malondialdehyde formation. The toxicity of CsA but not tamoxifen was increased by the glutathione synthesis inhibitor, buthionine-S.R-sulphoximine, and decreased by the glutathione precursor, L-cysteine. Thus, while both CsA and tamoxifen toxicities involved lipid peroxidation, reduced glutathione (or sulphydryl groups) protected against CsA but not tamoxifen.

3. CsA was metabolized to M1 and/or M17 in HepG2 cells. The effects of the cytochrome P450 inhibitors, ketoconazole and metyrapone, indicated that P450 played a role in the toxicity of CsA but not tamoxifen. The effects of superoxide dismutase and cytochrome c indicated that tamoxifen toxicity involved superoxide formation.

4. These results show that several oxidative mechanisms of drug toxicity operate in HepG2 cells.     

吡非尼酮对肝癌HepG2细胞增殖和凋亡的影响(“豪森杯”优秀论文三等奖)

目的：研究吡非尼酮（pirfenidone,PF）对人肝癌细胞系HepG2增殖和凋亡的影响。方法：CCK-8法测定不同浓度PF对HepG2细胞增殖活性的影响;Hoechst 33258荧光染色法观察PF处理后HepG2细胞形态的变化;流式细胞仪检测细胞凋亡率。结果：PF对HepG2细胞具有显著增殖抑制作用,并呈浓度和时间依赖性;Hoechst 33258染色可见PF处理后细胞出现典型的凋亡形态学变化;流式细胞仪检测结果显示,与空白组比较,PF处理后的HepG2细胞凋亡率显著增加（P﹤0.01）。结论：PF对人肝癌细胞系HepG2细胞增殖具有抑制作用,且与诱导HepG2细胞凋亡有关。     

Enhancement of diallyl disulfide-induced apoptosis by inhibitors of MAPKs in human HepG2 hepatoma cells

We examined the effects of diallyl disulfide (DADS), an oil-soluble organosulfur compound found in garlic, on human HepG2 hepatoma cells to better understand its effect on apoptosis and apoptosis-related genes. Our study has demonstrated that DADS affects cell proliferation activity and viability and elicits typical apoptotic morphologic changes (chromatic condensation and nuclear fragmentation) in human HepG2 hepatoma cells. Also, treatment with DADS induces a temporary increase in phosphorylated p38 MAPK (phospho-p38) and phosphorylated p42/44 MAPK (phospho-p42/p44) in a time- and concentration-dependent manner. Inhibition of activated/phosphorylated mitogen-activated protein kinase (MAPK) with phospho-p38 or phospho-p42/44 specific inhibitors, SB203580 or U0126, induces apoptosis without DADS treatment, indicating that at least the endogenous activated forms of p38 MAPK and p42/p44 MAPK markedly exert cytoprotective roles from cell apoptosis in the HepG2 hepatoma cells. Combined treatment with these inhibitors followed by DADS further enhances the DADS-induced apoptosis. Taken together, these results show that both DADS and the specific inhibitors of MAPKs could induce apoptosis in HepG2 hepatoma cells and that the MAPKs inhibitors further enhance the apoptotic effect in DADS-treated HepG2 hepatoma cells.     

Glycoborinine induces apoptosis through mitochondrial pathway in HepG2 cells

Glycoborinine (GB), a natural carbazole alkaloid isolated from Glycosmis pentaphylla, has been shown to be a potential molecule against cancer cells. In this study, the cell-signaling pathway of its anti-tumor activity was investigated. MTT assay result showed that GB inhibited HepG2 cell proliferation in a dose- and time-dependent manner and 50% inhibiting concentration (IC₅₀) of GB-induced cell death was 39.7 μM for a period of 48 h. GB-induced HepG2 apoptosis was confirmed by Hochest 33258 staining and PI staining. The level of reactive oxygen species (ROS) was measured with H₂DCF-DA staining and the change of mitochondrial membrane potential (△Ψ^m) was analyzed with tetrechloro-tetraethylbenzimidazolcarbocyanine iodide (JC-1) probe. Results showed that GB at 12.5, 25, and 50 μM promoted ROS production. GB induced HepG2 apoptosis through a mitochondrial apoptotic pathway, which was demonstrated by GB-induced increase in the ratio of Bax/Bcl-2, cytochrome C release, the ratio of cleaved caspase-3/procaspase-3, and the ratio of cleaved poly ADP-ribose polymerase (cleaved PARP)/poly ADP-ribose polymerase (PARP). To summarize, this study demonstrated that GB could induce HepG2 apoptosis through the mitochondrial-dependent pathway, which might provide a promising approach to cure liver cancer with GB.     

Molecular mechanisms of ZD1839 （Iressa）-induced apoptosis in human leukemic U937 cells

Aim： To investigate the molecular mechanisms of ZD 1839-induced apoptosis in human leukemic U937 cells. Methods： The inhibition of human leukemic U937 cell growth was assessed by 3-（4,5-dimethyl-2-thiazolyl）-2,5-diphnyl-2H-tetrazolim bromide （MTT） assays, lactate dehydrogenase （LDH） release, and cell cycle distribution. The expression of anti- and pro-apoptotic proteins was detected by Western blot analysis. Results： This study demonstrated that ZD1839 induced apoptosis in leukemic U937 cells by the downregulation of Bcl-2, caspase activation and subsequent apoptotic features. Cotreatment with ZD 1839 and the caspase- 3 inhibitor z-DEVD-fmk blocked apoptosis, indicating that caspase-3 activation is at least partially responsible for ZD 1839-induced apoptosis. The ectopic expression of Bcl-2 attenuated caspase-3 activation, PARP cleavage, and subsequent indicators of apoptosis, including sub-G1 DNA content and LDH release. These results indicate that the downregulation of Bcl-2 plays a major role in the initiation of ZD1839-induced apoptosis, and that the activation of a caspase cascade is involved in the execution of apoptosis. Furthermore, ZD1839 treatment triggered the activation of p38 mitogen-activated protein kinase （MAPK） and the downregulation of c-Jun-N-terminal kinase （JNK）, extracellular signal-regulated kinase （ERK） and phosphatidyl inositol 3-kinase （PI3K）/Akt. The inhibition of the ERK and PI3K/Akt pathways also significantly increased cellular death. Conclusion： ZD 1839 activated caspase-3 and the inhibited Bcl-2 in human leukemic U937 cells through the downregulation of the ERK and PI3K/Akt pathways.     

丹酚酸C诱导肝癌HepG2细胞有丝分裂阻滞及凋亡的研究

目的研究丹酚酸C(salvianolic acid C,SalC)的体外抗肿瘤细胞增殖作用及其分子机制。方法 MTT法检测Sal C对人肿瘤细胞的增殖抑制作用,流式细胞术检测细胞周期分布及细胞凋亡,Giemsa染色进行细胞有丝分裂的形态学观察,微管蛋白聚合实验检测Sal C对微管蛋白聚合活性的影响,比色法检测细胞中Caspase-3和Caspase-6的活性。结果丹酚酸C能抑制多种人肿瘤细胞增殖,其中对HepG2细胞的抑制作用较明显。流式细胞术分析发现Sal C使HepG2细胞阻滞于G2/M期并随作用时间延长出现明显的凋亡峰,细胞中Caspase-3和Caspase-6的活性升高。Gi-emsa染色提示HepG2细胞发生有丝分裂阻滞。Sal C能明显抑制微管蛋白的聚合。结论 Sal C具有抗肿瘤细胞增殖活性,通过抑制微管蛋白聚合诱导细胞有丝分裂阻滞从而诱导凋亡。     

Role of reactive oxygen species in apoptosis induced by N-ethylmaleimide in HepG2 human hepatoblastoma cells.

We have previously reported that N-ethylmaleimide induces apoptosis through activation of K(+), Cl(-)-cotransport in HepG2 human hepatoblastoma cells. In this study, we investigated the role for reactive oxygen species as a mediator of the apoptosis induced by N-ethylmaleimide. N-ethylmaleimide induced a significant elevation of intracellular level of reactive oxygen species. Treatment with antioxidants (N-acetyl cysteine, N,N'-diphenyl-p-phenylenediamine) which markedly suppressed generation of reactive oxygen species, significantly inhibited the N-ethylmaleimide-induced activation of K(+), Cl(-)-cotransport and apoptosis. Inhibitors of NADPH oxidase (diphenylene iodonium, apocynin, D-(+)-neopterine) also significantly blunted the generation of reactive oxygen species, activation of K(+), Cl(-)-cotransport and apoptosis induced by N-ethylmaleimide. These results suggest that reactive oxygen species generated through activation of NADPH oxidase may play a role in the N-ethylmaleimide-induced stimulation of K(+), Cl(-)-cotransport and apoptosis in HepG2 cells.     

血根碱通过诱导活性氧促进HepG2细胞凋亡的机制研究

目的研究血根碱对Hep G2细胞中活性氧(ROS)调控细胞凋亡途径的影响。方法采用血根碱干预Hep G2细胞,MTT法检测血根碱对细胞活性的影响;DCFH-DA和DHE染色观察血根碱作用Hep G2细胞12 h后细胞内ROS的变化;Hoechst 33342和Annexin V/PI染色检测细胞凋亡;Rho123染色检测细胞线粒体膜电位;Western blot检测凋亡相关蛋白的表达。结果随着血根碱药物浓度的增加,Hep G2细胞活力明显被抑制;血根碱可以明显提高Hep G2细胞内的ROS含量,并且降低线粒体膜电位,促进细胞凋亡;Western blot检测发现血根碱促进Bax、cleaved-caspase-3和细胞质Cyt-C的表达,抑制Bcl-2蛋白的表达。结论血根碱通过升高细胞内ROS的含量,激活线粒体凋亡途径,进而促进Hep G2细胞发生凋亡。     

不同浓度依托咪酯诱导人肝癌HepG2细胞体外凋亡的研究

目的探讨不同浓度的依托咪酯是否具有直接诱导人肝癌HepG2细胞凋亡的作用,寻找依托咪酯临床治疗的新途径。方法人肝癌细胞株HepG2体外扩增培养备用,选取不同浓度的依托咪酯E1、E2、E3和对照组（空白）,分别培养12h、24h、48h后观察。结果与空白对照组相比,培养12h、24h、48h后E1组、E2组人肝癌细胞株HepG2细胞凋亡率无明显差异（P〉0．05）,E3组凋亡率不断增加,具有显著性差异（P〈0．05）;随着培养时间的延长及浓度的不断增加,E1与E2组对比人肝癌细胞株HepG2细胞凋亡率无明显差异（t=1．732,P〉0．05）,E1与E3组对比人肝癌细胞株HepG2细胞凋亡率具有显著性差异（t=1．864,P〈0．05）,E2与E3组对比人肝癌细胞株HepG2细胞凋亡率具有明显差异（f=1．691,P〈0．05）。结论依托咪酯在临床安全有效的浓度下不直接诱导人肝癌HepG2细胞的体外凋亡,浓度及时间达到一定峰值时可具有直接诱导人肝癌HepG2细胞体外凋亡的作用。     

Olaquindox induces apoptosis through the mitochondrial pathway in HepG2 cells

Olaquindox is used in China as feed additive for growth promotion in pigs. Recently, we have demonstrated that olaquindox induced genome DNA damage and oxidative stress in HepG2 cells. The aim of this study was to explore the molecular mechanism of cell cycle arrest and apoptosis induced by olaquindox in HepG2 cells. In the present study olaquindox induced cell cycle arrest to the S phase and dose-dependent apoptotic cell death in HepG2 cells, indicated by accumulation of sub-G1 cell population, nuclear condenstion, DNA fragmentation, caspases activation and PARP cleavage. Meanwhile, the data showed that olaquindox triggered ROS-mediated apoptosis in HepG2 cells correlated with both the mitochondrial DNA damage and nuclear DNA damage, collapse of Δψ_m, opening of mPTP, down-regulation of Bcl-2 and up-regulation of Bax. Furthermore, we also found that olaquindox increased the expression of p53 protein and induced the release of cytochrome C from mitochondria to cytosol. In conclusion, olaquindox induced apoptosis of HepG2 cells through a caspase-9 and -3 dependent mitochondrial pathway, involving p53, Bcl-2 family protein expression, Δψ_m disruption and mPTP opening.