Emodin induces apoptosis in human lung adenocarcinoma cells through a reactive oxygen species-dependent mitochondrial signaling pathway

Emodin, a natural anthraquinone derivative isolated from Rheum palmatum L., has been reported to exhibit anti-cancer effect on several human cancers such as liver cancers and lung cancers. However, the molecular mechanisms of emodin-mediated tumor regression have not been fully defined. In this study, we show that treatment with 50 μM emodin resulted in a pronounced release of cytochrome c, activation of caspase-2, -3, and -9, and apoptosis in human lung adenocarcinoma A549 cells. These events were accompanied by the inactivation of ERK and AKT, generation of reactive oxygen species (ROS), disruption of mitochondrial membrane potential (Δψ_m), decrease of mitochondrial Bcl-2, and increase of mitochondrial Bax content. Ectopic expression of Bcl-2, or treatment with aurintricarboxylic acid, furosemide or caspase inhibitors markedly blocked emodin-induced apoptosis. Conversely, pharmacologic ERK and AKT inhibition promoted emodin-induced apoptosis. Furthermore, the free radical scavenger ascorbic acid and N-acetylcysteine attenuated emodin-mediated ROS production, ERK and AKT inactivation, mitochondrial dysfunction, Bcl-2/Bax modulation, and apoptosis. Take together, these findings suggest that in A549 cells, emodin-mediated oxidative injury acts as an early and upstream change in the cell death cascade to antagonize cytoprotective ERK and AKT signaling, triggers mitochondrial dysfunction, Bcl-2 and Bax modulation, mitochondrial cytochrome c release, caspase activation, and consequent leading to apoptosis.     

Herbacetin induces apoptosis in HepG2 cells: Involvements of ROS and PI3K/Akt pathway

Herbacetin (HER) is a natural flavonoid compound that can be extracted from Ramose Scouring Rush Herb, and its biological and pharmacological activities lack of corresponding attention. In this study, the apoptotic effect of HER against the human hepatoma cell line (HepG2) was investigated. The results showed that HepG2 cells apoptosis occurred in a dose-dependent manner within 48 h incubated with HER, which was confirmed by DNA fragmentation, nuclear shrinkage, and poly (ADP-ribose) polymerase (PARP) cleavage. HER at 25–100 μM induced a mitochondria-dependent apoptotic pathway associated with Bcl-2/Bax ratio decrease, mitochondrial membrane potential (ΔΨ) collapse, cytochrome c release, and caspase-3 activation. Increasing expression of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) was also observed in HER-treated cells. Furthermore, the addition of a ROS inhibitor (N-Acetyl-l-cysteine, NAC) significantly attenuated the apoptosis induced by HER and also blocked the expression of PGC-1α protein. Additionally, HER effectively inhibited the phosphorylation of Akt and the phosphatidylinositol-3 kinase (PI3K) inhibitor LY294002 increased the inhibition effect of HER on Akt phosphorylation. These findings provide evidences that HER induces HepG2 apoptosis in a ROS-mediated mitochondria-dependent manner that correlate with the inactivation of the PI3K/Akt pathway.     

冬凌草甲素通过PI3K/Akt通路诱导MDA-MB-231细胞的凋亡

目的：研究冬凌草甲素对人乳腺癌MDA-MB-231细胞增殖产生的影响,初步探讨其作用机理。方法：体外培养人乳腺癌MDA-MB-231细胞,采用6、12、24μmol/L冬凌草甲素对其进行处理,采用倒置显微镜进行细胞形态学观察,MTT比色法检测细胞存活率,流式细胞术检测细胞凋亡率,Western blotting检测凋亡相关蛋白procaspase-3、PARP及Akt、p-Akt、p-GSK3β表达的变化。结果：冬凌草甲素作用MDA-MB-231细胞24h后,可观察到细胞凋亡的形态学改变,以24μmol/L组最为明显。实验组与对照组相比,细胞存活率显著降低、凋亡率显著升高（P〈0.01）,具有时间和剂量依赖性,凋亡相关蛋白procaspase-3下调,caspase-3底物PARP被逐步剪切,并伴随p-Akt、p-GSK3β蛋白水平下调（P〈0.05）。结论：冬凌草甲素可有效抑制人乳腺癌MDA-MB-231细胞的增殖,诱导其凋亡,机制与PI3K/Akt通路的抑制有关。     

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.     

蛇床子素通过PI3K/Akt通路诱导外阴鳞癌SW962细胞凋亡

目的探讨蛇床子素(osthole或osthol)能否通过PI3K/Akt通路诱导细胞凋亡,抑制细胞增殖。方法体外培养外阴鳞癌SW962细胞,加入不同浓度蛇床子素,MTT法检测细胞存活情况,DAPI染色观察细胞形态学变化;流式细胞术检测SW962细胞凋亡情况; Western blot检测Bcl-2、Bax、cleaved caspase-3、PI3K和p-Akt蛋白表达,及蛇床子素和IGF-1共作用下PI3K/Akt通路蛋白的变化。结果 MTT结果显示,蛇床子素呈浓度依赖性地抑制SW962细胞增殖;DAPI染色和流式细胞术结果显示,蛇床子素呈浓度依赖性诱导细胞凋亡。Western blot结果显示,蛇床子素能上调Bax和cleaved caspase-3蛋白表达,下调PI3K、p-Akt和Bcl-2蛋白表达。IGF-1诱导PI3K、p-Akt和Bcl-2蛋白表达增加,蛇床子素逆转IGF-1作用,3种蛋白表达下调。结论蛇床子素通过抑制PI3K/Akt通路,诱导外阴鳞癌SW962细胞凋亡,抑制细胞增殖。     

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.     

Fraxetin suppresses reactive oxygen species-dependent autophagy by the PI3K/Akt pathway to inhibit isoflurane-induced neurotoxicity in hippocampal neuronal cells

Isoflurane, a common volatile anesthetic, has been widely used to provide general anesthesia in operations. However, exposure to isoflurane may cause widespread neurotoxicity in the developing animal brain. Fraxetin, a natural coumarin derivative extracted from the bark of Fraxinus rhynchophylla, possesses versatile pharmacological properties including anti-oxidative, anti-inflammatory, and neuroprotective effects. However, the effect and action mechanism of fraxetin on neurotoxicity induced by isoflurane are unknown. Reactive oxygen species (ROS) generation, cell viability, lactate dehydrogenase (LDH) release, and apoptosis were estimated by 2′,7′-dichlorofluorescin-diacetate (DCFH-DA) staining, MTT, LDH release, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) staining assays, respectively. The protein levels of light chain 3 (LC3)-I, LC3-II, p62, protein kinase B (Akt), and phosphorylated Akt (p-Akt) were detected by western blot analysis. Isoflurane induced ROS, LDH release, apoptosis, and autophagy, but inhibited the viability in HT22 cells, which were overturned by fraxetin or ROS scavenger N-acetyl-L-cysteine. Fraxetin suppressed isoflurane-induced PI3K/Akt inactivation in HT22 cells. PI3K/Akt inactivation by LY294002 resisted the effects of fraxetin on isoflurane-induced autophagy and autophagy-modulated neurotoxicity in HT22 cells. In conclusion, fraxetin suppressed ROS-dependent autophagy by activating the PI3K/Akt pathway to inhibit isoflurane-induced neurotoxicity in hippocampal neuronal cells.     

Gypenosides induce apoptosis in human hepatoma Huh-7 cells through a calcium/reactive oxygen species-dependent mitochondrial pathway

We have previously reported that gypenosides induce apoptosis in human hepatocarcinoma Huh-7 cells through a mitochondria-dependent caspase-9 activation cascade. In order to further explore the critical events leading to apoptosis in gypenosides-treated cells, the following effects of gypenosides on components of the mitochondrial apoptotic pathway were examined: generation of reactive oxygen species (ROS), alteration of the mitochondrial membrane potential (MPT), and the subcellular distribution of Bcl-2 and Bax. We show that gypenosides-induced apoptosis was accompanied by the generation of intracellular ROS, disruption of MPT, and inactivation of ERK, as well as an increase in mitochondrial Bax and a decrease of mitochondrial Bcl-2 levels. Ectopic expression of Bcl-2 or treatment with furosemide attenuated gypenosides-triggered apoptosis. Treatment with ATA caused a drastic prevention of apoptosis and the gypenosides-mediated mitochondrial Bcl-2 decrease and Bax increase, but failed to inhibit ROS generation and MPT dysfunction. Incubation with antioxidants significantly inhibited gypenosides-mediated ROS generation, ERK inactivation, MPT and apoptosis. Moreover, an increase of the intracellular calcium ion (Ca(2+)) concentration rapidly occurred in gypenosides-treated Huh-7 cells. Buffering of the intracellular Ca(2+) increase with a Ca(2+) chelator BAMTA/AM blocked the gypenosides-elicited ERK inactivation, ROS generation, Bcl-2/Bax redistribution, mitochondrial dysfunction, and apoptosis. Based on these results, we propose that the rise in intracellular Ca(2+) concentration plays a pivotal role in the initiation of gypenosides-triggered apoptotic death.     

注射用核糖核酸Ⅱ通过活性氧介导的PI3K/Akt信号通路诱导人白血病细胞KG1a凋亡

目的研究注射用核糖核酸Ⅱ诱导人急性骨髓白血病细胞系KG1a细胞凋亡与PI3K/Akt信号通路和活性氧(ROS)的关系。方法流式细胞术(FCM)检测细胞周期和细胞内的ROS水平;免疫印迹法(Western blot)检测PI3K/Akt信号通路相关蛋白p-PI3K、p-Akt、p-MDM2、p21和周期相关蛋白cyclin D1、CDK4的表达;加入抗氧化剂N-乙酰半胱氨酸(NAC)后,检测p-PI3K、p-Akt和p53蛋白表达变化。结果 FCM结果显示,注射用核糖核酸Ⅱ可将KG1a细胞阻滞在G0/G1期,且ROS介导了细胞周期的阻滞; FCM检测ROS结果显示,KG1a细胞内ROS水平均随药物浓度增加而升高; Western blot结果显示,注射用核糖核酸Ⅱ下调pPI3K、p-Akt、p-MDM2和cyclin D1、CDK4的表达,上调p21的表达;与仅用注射用核糖核酸Ⅱ相比,经NAC预处理后再使用注射用核糖核酸Ⅱ,明显上调了磷酸化PI3K和Akt的表达,下调了p53的表达。结论注射用核糖核酸Ⅱ通过ROS介导的PI3K/Akt信号通路,诱导人急性骨髓白血病细胞系KG1a细胞凋亡。     

Chelerythrine hydrochloride inhibits proliferation and induces mitochondrial apoptosis in cervical cancer cells via PI3K/BAD signaling pathway

Cervical cancer is the fourth most common female cancer worldwide, and drug targeted therapy plays a crucial role in delaying the progression of cervical carcinoma. Chelerythrine hydrochloride (CHE) is a natural alkaloid, which is a focal point in anti-tumor research. In this study, we investigated the effect of CHE on HeLa cells by using MTT assay, RTCA, and colony formation assay. In addition, the flow cytometric analysis, immunofluorescence staining assay and western blot analysis were performed to study the mechanism of CHE. The results showed that CHE exhibited a significant inhibitory effect in HeLa cells, and it could suppress the expression of PI3K subunits in a dose-dependent manner. Moreover, we found that the treatment of CHE further restrained the downstream AKT/mTOR and PKCα signaling. In addition, CHE induced mitochondrial apoptosis of HeLa cells by regulating the BCL-2 family member's expression. Immunofluorescence staining assay indicated that AIF and Cytochrome C were translocated from mitochondria to cytoplasm or nucleus, and notable changes in mitochondrial morphology of HeLa cells were also observed. Finally, the aberrant expression of CHE led to the mitochondrial apoptosis by upregulating the expression of APAF1, Cleaved-Caspase9, Cleaved-Caspase3, and Cleaved-PARP. In summary, CHE suppresses the proliferation of HeLa cells by trigging the mitochondrial apoptosis through the PI3K/BAD signaling pathway.     

Homocysteine induces cell cycle G1 arrest in endothelial cells through the PI3K/Akt/FOXO signaling pathway

OBJECTIVE: High levels of homocysteine (Hcy) induce a sustained injury on arterial endothelial cells, which accelerates the development of thrombosis and atherosclerosis. Hcy specifically inhibits the growth of endothelial cells. The present study investigated the signaling pathways underlying this cell-cycle effect. METHODS: Human umbilical venous endothelial cells were treated with Hcy, and/or LY294002, okadaic acid, peroxovanadate (PV), antisense Akt, phosphorylation of Akt and FKHRL1 proteins. p27(kip1) protein levels were measured with Western blotting, and Akt kinase activity and cell cycle were measured with immunoprecipitation and flow cytometry, respectively. RESULTS: We demonstrate that Hcy induces dephosphorylation of Akt and FKHRL1 and upregulates the cyclin-dependent kinase inhibitors p27(kip1) in a time- and dose-dependent manner. Phosphatidylinositol-3 kinase (PI3K) activator PV and phosphatase 2A inhibitor okadaic acid could reverse it, which suggests it was dependent on PI3K activity. Moreover, Hcy induces cell cycle G1 phase arrest prevented by pretreatment with PV and okadaic acid. Transfection with specific antisense oligonucleotides to Akt further proves the observations. CONCLUSIONS: The studies implied that a novel signaling pathway, PI3K/Akt/FOXO, might play an important role in mediating cell cycle G1 arrest in endothelial cells.     

PI3K/Akt信号通路与肝纤维化

PI3K/Akt信号通路为细胞内重要信号传导通路之一,在促进细胞增殖、抑制凋亡的过程中发挥重要作用。PI3K/Akt信号通路与肝纤维化的发生、发展密切相关。通过干预PI3K/Akt信号通路,研究肝纤维化的发病机制和药物治疗是有意义的途径。该文就PI3K/Akt信号通路的构成、转导途径及其在肝纤维化中的作用作一综述。     

辛伐他汀通过线粒体途径诱导K562细胞凋亡

目的观察辛伐他汀诱导K562细胞凋亡不同时间的膜电位(Δψm),caspase-3、9和细胞色素C的改变,以推测其凋亡通路。方法采用浓度为20μmol.L-1的辛伐他汀处理K562细胞24、48、72 h,采用流式细胞技术检测细胞凋亡率和线粒体膜电位,分光光度法检测caspase-3、9蛋白活性,免疫组织化学法检测细胞色素C蛋白。结果浓度为20μmol.L-1辛伐他汀作用K562细胞24、48、72 h后,凋亡率分别为(6.1±0.35)%、(14.15±0.42)%(、30.70±0.65)%,随着凋亡率增加线粒体膜电位降低分别为(39.6±4.80)%,(24.4±2.45)%,(6.0±1.62)%;caspase-3、9蛋白活性与对照组相比上调,细胞浆内细胞色素C升高。结论辛伐他汀诱导K562细胞凋亡时线粒体膜电位下降,caspase-3、9活性增高和细胞色素C释放,推测辛伐他汀诱导K562细胞的凋亡可能经过线粒体凋亡途径。     

萘酰亚胺-多胺缀合物NNINspm通过PI_3 K/Akt信号通路诱导肝癌细胞凋亡

目的探讨新型萘酰亚胺-多胺缀合物NNINspm对多胺转运体的识别及诱导肝癌HepG2细胞凋亡的机制。方法以MTT法检测细胞毒性;流式细胞仪检测细胞周期、凋亡率及线粒体膜电位的变化;高内涵活细胞成像系统检测NNINspm对多胺转运体识别及Akt易位的影响;Western blot检测NNINspm对cytochrome C、14-3-3、Bad、Bcl-xL、mTOR、p70S6K、Cdk4、p27kip1、Akt、Caspase-3、Caspase-9等蛋白表达的影响。结果NNINspm具有良好的多胺转运体识别能力及肿瘤细胞靶向性,其通过抑制Akt磷酸化从而引起一系列的信号分子发生改变,如14-3-3蛋白与Bad解离并与Bcl-xL结合,随后引起cytochromeC释放及caspase-9及caspase-3活化并最终诱导细胞凋亡;此外,NNINspm诱导mTOR和p70S6K脱磷酸化,Cdk4下调及p27kip1上调并最终诱导细胞周期阻滞于G0/G1期。结论NNINspm通过PI3K/Akt信号途径诱导肝癌HepG2细胞凋亡。     

Ridaifen-SB8, a novel tamoxifen derivative,induces apoptosis via reactive oxygen species-dependent signaling pathway

Tamoxifen is an anticancer agent widely used for treatment of estrogen receptor (ERα)-positive breast cancer. We previously developed a novel synthesis of tamoxifen and its derivatives, named Ridaifens (RIDs). Some of them, including RID-SB8, exhibited a stronger anticancer activity than tamoxifen in ERα-positive MCF-7 cells while having lost the affinity for ERα, suggesting an ERα-independent anticancer mode of action. In this study, we investigated the underlying mechanism by which RID-SB8 exerts anticancer activity. As expected, anticancer activity of RID-SB8 was not influenced upon knockdown of ERα expression in MCF-7 cells. RID-SB8 exerted similar anticancer effects on thirteen ERα-negative cancer cell lines including human gliosarcoma SF539 cells. In SF539 cells, RID-SB8 triggered loss of mitochondrial membrane potential (ΔΨ_m) and progression of apoptosis accompanied by activation of caspases and translocation of apoptosis-inducing factor (AIF) to the nucleus. Furthermore, it induced reactive oxygen species (ROS), and a ROS scavenger, N-acetylcysteine (NAC), canceled loss of ΔΨ_m and progression of apoptosis triggered by RID-SB8. Using fifteen human cancer cell lines, we demonstrated a significant correlation between RID-SB8 concentration required for ROS production and that required for cytotoxic effect across these cell lines, but such correlation was not observed for tamoxifen. Finally, the selective induction of ROS and cytotoxic effect on cancer cells by RID-SB8 were confirmed. From these results, we concluded that RID-SB8 exerts an anticancer effect via a mode of action distinct from tamoxifen, and that RID-SB8 could become a promising anticancer lead compound which selectively induces ROS formation and apoptosis in cancer cells.     

A novel quinazolinone chalcone derivative induces mitochondrial dependent apoptosis and inhibits PI3K/Akt/mTOR signaling pathway in human colon cancer HCT-116 cells

We have synthesized a novel quinazolinone chalcone derivative (QC) and first time reported its in-vitro and in-vivo anticancer potential. It inhibited the cell proliferation of different cancer cell lines like PC-3, Panc-1, Mia-Paca-2, A549, MCF-7 and HCT-116. It induces apoptosis as measured by several biological endpoints such as apoptotic body formation, evident by Hoechst and scanning electron microscopy, enhanced annexinV-FITC binding of the cells, increased sub-G0 cell fraction, loss of mitochondrial membrane potential (Δψm), reduction of Bcl-2/Bax ratio, activation of caspase-9, caspase-3 and PARP-1 (poly-ADP Ribose polymerase) cleavage in HCT-116 cells. In spite of apoptosis, QC significantly hammers the downstream and upstream signaling cascade of PI3K/Akt/mTOR pathway and cell cycle regulator Skp-2, p21 and p27. Interestingly, QC induces the S and G2/M phase of HCT-116 cells at experimental doses. QC inhibits the tumor growth of Ehrlich ascites carcinoma (EAC), Ehrlich tumor (ET, solid) and sarcoma-180(solid) mice models. Furthermore, it was found to be non-toxic as no animal mortality (0/7) occurred during experimental doses. The present study provides an insight of anticancer potential of QC, which may be useful in managing and treating cancer.