The augmentation of TNFalpha-induced cell death in murine L929 fibrosarcoma by the pan-caspase inhibitor Z-VAD-fmk through pre-mitochondrial and MAPK-dependent pathways

We investigated the mechanism of the pan-caspase inhibitor z-VAD-fmk's augmentation of TNFalpha-induced L929 cell death and found this mechanism differs from that of TNFalpha-induced L929 cell death. In the presence of 20 ng/ml TNFalpha, z-VAD-fmk initiated apoptosis and necrosis in the majority of L929 cells as measured by an agarose gel electrophoresis and lactate dehydrogenase(LDH)activity based assay. Mitochondrial permeability transition (MPT) inhibitor (cyclosporine A) effectively inhibited z-VAD-fmk-augmented cell death. In addition, z-VAD-fmk plus TNFalpha increased Bax expression without affecting Bcl-2 and cytochrome expression. Western-blot analysis showed that z-VAD-fmk plus TNFalpha caused persistent JNK activation and ERK inactivation. Poly(ADP-ribose) polymerase (PARP) inhibitor (DPQ) effectively reversed the cell death which was augmented by z-VAD-fmk, and z-VAD-fmk plus TNFalpha also caused PARP cleavage to an 85 KDa fragment. These results indicate that in the presence of TNFalpha, z-VAD-fmk further augments cell death which requires the mitochondrial permeability transition and the JNK activation. However, we did not detect the changes in cytochrome c expression and the participation of caspase-9 in this process, suggesting that there might exist an unknown signal pathway(s) from the mitochondria to the downstream protein PARP, which is cleaved in a caspase-independent manner.     

The cell death of C6 astrocytoma cells induced by oridonin and its mechanism

Many studies have shown that oridonin, a compound purified from Rabdosia rubescens, was able to suppress proliferation and induce apoptosis in many cell types. In this study, In order to investigate the proliferation suppression and apoptosis-inducing effect of oridonin on Rat C6 astrocytoma cells, we treated C6 cells with different concentrations of oridonin for various time intervals. Oridonin concentration-time viability curve were used to test the effect of oridonin on the C6 cells. The distribution of cell cycle and percentage of apoptosis cells was analyzed by flow cytometry. The protein expression of Bax, Bcl-2, and caspase-3 in the C6 cells was detected by western blot analysis. The results of viability curve demonstrated that oridonin induced suppression of proliferation in a concentration- and time-dependent manner. Hochest 33258 staining and flow cytometry revealed that oridonin induced apoptosis and arrested the entry into G2/M phase of C6 cells. According to the results of Western blot, oridonin down-regulated Bcl-2, up-regulated Bax protein, and activated caspase-3 in the oridonin-treated C6 cells. All together, our results suggested that oridonin can cause the suppression of proliferation in C6 astrocytoma cells and the cell death induced by oridonin might be associated with mitochondria- mediated apoptosis by activating caspase-3.     

Oridonin induces apoptosis and senescence by increasing hydrogen peroxide and glutathione depletion in colorectal cancer cells

We recently demonstrated that oridonin could induce apoptosis and senescence of colon cancer cells in vitro and in vivo. However, the underlying mechanism remains unknown. In this study, the involvement of reactive oxygen species in oridonin-induced cell death and senescence was investigated in colon adenocarcinoma-derived SW1116 cells. Oridonin increased intracellular hydrogen peroxide levels and reduced the glutathione content in a dose-dependent manner. N-acetylcysteine, a reactive oxygen species scavenger, not only blocked the oridonin-induced increase in hydrogen peroxide and glutathione depletion, but also blocked apoptosis and senescence induced by oridonin, as evidenced by the decrease in Annexin V and senescence-associated β-galactosidase- positive cells and the inhibition of oridonin-induced upregulation of p53 and p16 and downregulation of c-Myc. Moreover, exogenous catalase could inhibit the increase in hydrogen peroxide and apoptosis induced by oridonin, but not the glutathione depletion and senescence. Furthermore, thioredoxin reductase (TrxR) activity was reduced by oridonin in vitro and in cells, which may cause the increase in hydrogen peroxide. In conclusion, the increase in hydrogen peroxide and glutathione depletion account for oridonin-induced apoptosis and senescence in colorectal cancer cells, and TrxR inhibition is involved in this process. Given the importance of TrxR as a novel cancer target in colon cancer, oridonin would be a promising clinical candidate. The mechanism of oridonin-induced inhibition of TrxR warrants further investigation.     

Cytochrome c-dependent activation of caspase-3 by tumor necrosis factor requires induction of the mitochondrial permeability transition

The killing of L929 mouse fibroblasts by tumor necrosis factor-alpha (TNF-alpha) in the presence of 0.5 microg/ml actinomycin D (Act D) is prevented by inhibition of the mitochondrial permeability transition (MPT) with cyclosporin A (CyA) in combination with the phospholipase A(2) inhibitor aristolochic acid (ArA). The MPT is accompanied by the release of cytochrome c from the mitochondria, caspase-8 and caspase-3 activation in the cytosol, cleavage of the nuclear enzyme poly(ADP-ribose)polymerase (PARP), and DNA fragmentation, all of which were inhibited by CyA plus ArA. The caspase-3 inhibitor z-Asp-Glu-Val-aspartic acid fluoromethyl-ketone (Z-DEVD-FMK) did not prevent the loss of viability or the redistribution of cytochrome c, but it did prevent caspase-3 activation, PARP cleavage, and DNA fragmentation. Inhibition of the MPT reduced the activation of caspase-8 to the level occurring with TNF-alpha alone (no ActD). The caspase-8 inhibitor z-Ile-Glu(OMe)-Thr-Asp(OMe) fluoromethylketone (Z-IETD-FMK) did not prevent the cell killing and decreased only slightly the translocation of Bid to the mitochondria. These data indicate that induction of the MTP by TNF-alpha causes a release of cytochrome c, caspase-3 activation with PARP cleavage and DNA fragmentation. The loss of viability is dependent on the MPT but independent of the activation of caspase-3. The activation of caspase-8 is not dependent on the MPT. There is no evidence linking this enzyme to the loss of viability. Thus, the killing of L929 fibroblasts by TNF-alpha can occur in the absence of either caspase-3 or caspase-8 activity. Alternatively, cell death can be prevented despite an activation of caspase-8.     

Oridonin-induced apoptosis of Jurkat cells and its mechanism

Jurkat cells in culture medium in vitro were exposed to different concentrations of oridonin. The proliferation rate of the cells was measured by MTT assay, cell apoptotic rate was detected by flow cytometry, morphology of cell apoptosis was observed by Hoechst 33258 fluorescence staining, DNA fragmentation was assayed by agarose gel electrophoresis, caspase-3 and poly(ADP-ribose) polymerase (PARP) expressions were detected by Western blotting using polyclonal anti-caspase-3 antibody and mouse anti-human PARP monoclonal antibodies, and caspase-3 activity was assayed with a colorimetric assay kit before and after apoptosis had occurred. Oridonin (over 32 mol/l) inhibited the growth of Jurkat cells and caused significant apoptosis. The suppression was both time-dependent and dose-dependent. Marked morphological changes of cell apoptosis, including condensation of chromatin and nuclear fragmentation, were clearly observed by Hoechst 33258 fluorescence staining, as well as by agarose gel electrophoresis. Western blotting showed cleavage of the caspase-3 zymogen protein (32 kDa), with the appearance of its 17 kDa subunit, and a cleaved 89-kDa fragment of 116 kDa PARP was also found, together with a concurrent increase in caspase-3 apoptotic activity. Oridonin can induce apoptosis in Jurkat cells via activation of caspase-3; the results indicate that oridonin might be an important potential anti-leukaemia reagent.     

冬凌草甲素增强巨噬细胞对凋亡的U937细胞的吞噬作用

目的：研究具有诱导肿瘤细胞凋亡活性的冬凌草甲素，促进巨噬细胞对因凋亡的肿瘤细胞的吞噬作用。 方法： DNA凝胶电泳检测UV照射（2.4 J/cm2, 4 min）的人组织淋巴瘤U937细胞凋亡；Giemsa染色，Hoechst 33258染色，镜下检测计数吞噬作用。 结果： UV照射（2.4 J/cm2, 4 min）诱导U937细胞发生凋亡，琼脂糖凝胶电泳可见凋亡典型的DNA梯带。2.7 μmol·L^-1的冬凌草甲素具有增强U937分化的巨噬细胞对UV照射诱导凋亡的U937细胞的吞噬作用，并呈时间剂量依赖性，但对非特异性荧光颗粒的吞噬效果较弱。加入抗TNFα和抗IL-1β的抗体，培养12 h, 吞噬增强作用明显受抑制。冬凌草甲素在人外周血来源的巨噬细胞吞噬凋亡的U937细胞过程中同样发挥增强吞噬的效果。 结论： 冬凌草甲素可特异地增强巨噬细胞对凋亡的U937细胞的吞噬作用，其吞噬机制是通过诱导巨噬细胞TNFα和IL-1β的释放。     

半胱氨酸蛋白酶-3抑制剂对大鼠缺血再灌流脑区神经元凋亡的影响

目的探讨半胱氨酸蛋白酶3(caspase3)抑制剂z DEVD fmk对大脑皮层缺血再灌流区神经元凋亡的影响。方法制备大脑中动脉栓塞再灌流大鼠模型,于再灌流前向治疗组缺血侧脑室注射z DEVD fmk(7μg/kg)。采用Western印迹分析、TUNEL和免疫组织化学染色(SPAB法)等方法,检测各组颞顶叶皮层缺血再灌流区caspase3表达和活化、多(ADP核糖)聚合酶(PARP)表达和切割灭活及神经元凋亡。结果未治疗组(A组)、二甲基亚砜对照组(B组)、z DEVD fmk治疗组(C组),再灌流1h及24h缺血脑区的caspase3前体含量分别为16.7±3.0、11.5±3.0、47.5±3.5及76.1±3.5、71.3±6.4、88.2±5.5;12000caspase3切割片段含量分别为8.2±2.3、9.4±1.2、4.3±1.6及59.0±6.3、60.5±7.2、17.3±2.8;PARP含量分别为12.6±3.0、13.9±2.0、53.7±4.1及67.5±8.6、61.1±6.6、93.6±4.1;24000PARP切割片段含量分别为6.0±0.7、6.6±1.2、3.6±1.1及27.4±2.6、25.8±3.2、12.1±2.8(相对灰度值);凋亡神经元密度分别为83.3±7.5、84.3±5.7、45.7±4.0及197.4±11.8、185.2±11.2、99.1±5.8(个/0.1mm2,x±s)。3组各自再灌流不同时间点缺血脑区以上5种指标的差异均有统计学意义(P<0.05～0.001);C组再灌流各时间点缺血脑区以上5种指标与A组及B组对应时间点比较,差异也均有统计学意义(P<0.05～0.001),但A、B两组间比较差异无统计学意义(P>0.05);各组再灌流不同时间点这5种指标的变化彼此间均呈正相关(r=0.630～0.942,P<0.01)。各组缺血再灌流脑区表达PARP的细胞主要是神经元,但3组间比较其密度差别不大。结论再灌流激发的caspase3表达和活化异常增加使PARP过度切割灭活,是再灌流导致缺血脑区受损神经元凋亡的重要分子机制;z DEVD fmk可通过抑制caspase3活性和自活化,减少PARP切割灭活,阻止受损神经元凋亡。     

SNS-032诱导弥漫性大B淋巴瘤OCI-LY-19细胞株凋亡及其作用机制的研究

 目的： 研究SNS-032对弥漫性大B淋巴瘤细胞株OCI-LY-19凋亡的影响并探讨其作用机制。方法：应用MTS法观察不同浓度的SNS-032对OCI-LY-19细胞活力的影响;用PI单染法观察SNS-032对OCI-LY-19细胞诱导死亡的影响;Annexin V/PI双染流式细胞术分析不同浓度SNS-032对OCI-LY-19细胞凋亡的影响;Western blotting检测细胞凋亡相关蛋白和细胞增殖相关蛋白的表达情况。结果：SNS-032明显抑制OCI-LY-19细胞活力,半数抑制浓度为0.358 μmol/L;随SNS-032作用时间延长与浓度升高,凋亡细胞数逐渐增多;SNS-032可以时间与剂量依赖性地引起凋亡相关蛋白聚腺苷二磷酸-核糖聚合酶(PARP)的切割,caspase-3前体(procaspase-3)、caspase-9前体(procaspase-9)、X连锁凋亡抑制蛋白(XIAP)与髓样细胞白血病1(Mcl-1)的表达下降,而cleaved caspase-3和cleaved caspase-9表达明显增加;与细胞增殖相关的蛋白丝/苏氨酸激酶(Akt)、磷酸化Akt(p-Akt)、信号转导子及转录激活子5 (STAT5)、磷酸化STAT5（p-STAT5）、细胞外信号调节激酶(ERK)和磷酸化ERK(p-ERK)表达下降,而ERK总蛋白无明显变化。结论：SNS-032能抑制弥漫性大B淋巴瘤细胞株OCI-LY-19的生长,诱导其凋亡,可能的机制是抑制了相关抗凋亡蛋白的表达,激活了caspase级联反应,同时抑制了与细胞增殖相关的JAKs/STATs、MEK/ERK和PI3K-Akt信号转导通路的表达与活化。     

冬凌草甲素对人肝癌MHCC-97H细胞系侵袭和迁移的作用

目的:探讨冬凌草甲素(oridonin)对肝癌细胞侵袭和迁移的影响及其机制。方法:采用细胞培养技术培养人肝细胞癌MHCC-97H细胞,用不同浓度的冬凌草甲素处理肝癌细胞,采用划痕实验检测细胞的迁移能力;Transwell实验测定细胞的侵袭能力;黏附实验评价细胞的黏附能力;Western blot法检测LIM激酶1(LIMK-1)、丝切蛋白(cofilin)和磷酸化cofilin(p-cofilin)蛋白水平的改变。结果:冬凌草甲素可明显降低肝癌细胞的体外侵袭、迁移及黏附能力(P0.05),且在一定浓度范围内具有明显的量效关系。冬凌草甲素干预处理细胞后,cofilin的蛋白水平无明显变化,LIMK-1和p-cofilin的蛋白水平明显下调。结论:冬凌草甲素体外具有抑制肝癌MHCC-97H细胞侵袭和迁移的作用,其机制可能与调控LIMK-1/cofilin信号通路有关。     

Synphilin-1 exhibits trophic and protective effects against Rotenone toxicity

Synphilin-1 is a cytoplasmic protein with unclear function. Synphilin-1 has been identified as an interaction partner of α-synuclein. The interaction between synphilin-1 and α-synuclein has implications in Parkinson's disease. In this study, we stably overexpressed human synphilin-1 in mouse N1E-115 neuroblastoma cells. We found that overexpression of synphilin-1 shortened cell growth doubling time and increased neurite outgrowth. Knockdown of endogenous synphilin-1 caused neuronal toxicity and shortened neurite outgrowth. We further found that synphilin-1 increased activation of the extracellular signal-regulated kinases (ERK1/2) and mediated neurite outgrowth. Rotenone, mitochondrial complex I inhibitor, has been shown previously to induce dopaminergic neurodegeneration and Parkinsonism in rats and Drosophila. We found that Rotenone induced apoptotic cell death in N1E-115 cells via caspase-3 activation and poly (ADP-ribose) polymerase (PARP) cleavage. Overexpression of synphilin-1 significantly reduced Rotenone-induced cell death, caspase-3 activation and PARP cleavage. The results indicate that synphilin-1 displays trophic and protective effects in vitro, suggesting that synphilin-1 may play a protective role in Parkinson's disease (PD) pathogenesis and may lead to a potential therapeutic target for PD intervention.     

Photodynamic therapy induced Fas-mediated apoptosis in human carcinoma cells

Photodynamic therapy (PDT) is a clinical approach that utilizes light-activated drugs for the treatment of a variety of pathologic conditions. Human poorly (CNE2) and moderately differentiated (TW0-1) human nasopharyngeal carcinoma (NPC) cells undergo rapid apoptosis when treated with PDT sensitized with Hypocrellin A (HA) and Hypocrellin B (HB). It has been shown that these compounds have a strong photodynamic effect on tumors and viruses. The initiating events of PDT sensitized HA and HB-induced apoptosis are poorly defined. In the current study, we sought to determine whether Fas/FasL upregulation and involvement of mitochondrial events are an early event in HA and HB-treated PDT induced apoptosis. Loss of mitochondrial transmembrane potential, release of cytochrome c, involvement of caspases-8 and -3 and the status caspase-3 specific substrate PARP, were evaluated in PDT treated tumor cells. Photoactivation of HA and HB enhanced both CD95/CD95L expression and induced CD95-signaling dependent cell death in all tumor cell lines studied. CD95/ CD95L expression appeared within 2 h following light activation and appeared to be a primary event in PDT induced apoptosis. Furthermore, these results indicate that release of mitochondrial cytochrome c into the cytoplasm is a secondary event following the activation of initiator caspase-8 preceding caspase-3 activation, cleavage of PARP and DNA fragmentation. Cytochrome c appeared in the cytosol within 2-3 h post PDT. Cleavage of PARP was observed at 3-4 h following PDT and caspase-3 specific inhibitor DEVD-CHO and broad-spectrum caspases inhibitor z-VAD-fmk blocked caspase-3 activation and PARP cleavage suggesting that caspase-3 plays an important role in HA and HB-induced apoptosis.     

Poly(ADP-ribose)polymerase activation mediates lung epithelial cell death in vitro but is not essential in hyperoxia-induced lung injury

Hyperoxia induces extensive DNA damage and lung cell death by apoptotic and nonapoptotic pathways. We analyzed the regulation of Poly(ADP-ribose)polymerase-1 (PARP-1), a nuclear enzyme activated by DNA damage, and its relation to cell death during hyperoxia in vitro and in vivo. In lung epithelial-derived A549 cells, which are known to die by necrosis when exposed to oxygen, a minimal amount of PARP-1 was cleaved, correlating with the absence of active caspase-3. Conversely, in primary lung fibroblasts, which die mainly by apoptosis, the complete cleavage of PARP-1 was concomitant to the induction of active caspase-3, as assessed by Western blot and caspase activity. Blockade of caspase activity by Z-VAD reduced the amount of cleaved PARP-1 in fibroblasts. Hyperoxia induced PARP activity in both cell types, as revealed by poly-ADP-ribose accumulation. In A549 cells, the final outcome of necrosis was dependent on PARP activity because it was prevented by the PARP inhibitor 3-aminobenzamide. In contrast, apoptosis of lung fibroblasts was not sensitive to 3-aminobenzamide and was not affected by PARP-1 deletion. In vivo, despite evidence of PARP activation in hyperoxia-exposed mouse lungs, absence of PARP-1 did not change the extent of lung damage, arguing for redundant oxidative stress-induced cell death pathways.     

Central administration of a caspase inhibitor impairs shuttle-box performance in rats

Recent studies suggest that caspase-3-mediated mechanisms are essential for neuronal plasticity. N-benzyloxycarbonyl-Asp(OMe)-Glu(OMe)-Val- Asp(OMe)-fluoromethyl ketone (z-DEVD-fmk), a caspase inhibitor with predominant specificity toward caspase-3, has been shown to block long-term potentiation in hippocampal slices. Intrahippocampal infusion of a caspase-3 inhibitor to rats has been shown to significantly impair spatial memory in the water maze. The present work was designed to study whether i.c.v. administration of a caspase-3 inhibitor z-DEVD-fmk impairs learning in other tasks related to specific forms of memory in rats. The rats received bilateral injections of z-DEVD-fmk or N-benzyloxycarbonyl-Phe-Ala-fluoromethyl ketone (z-FA-fmk) ("control" peptide) at a dose of 3 nmol. Administration of z-DEVD-fmk significantly decreased the number of avoidance reactions in some blocks of trials in the active avoidance (shuttle box) learning, while z-FA-fmk had no effect as compared with intact rats. However, only a slight effect of the caspase inhibitor across the session was found. z-DEVD-fmk impaired development of some essential components of the two-way active avoidance performance, such as escape reaction, conditioned fear reaction, and inter-trial crossings. Measurement of caspase-3 activity in rat brain regions involved in active avoidance learning revealed most expressed z-DEVD-fmk-related inhibition of the enzyme activity (about 30%) in the fronto-parietal cortex. A similar effect was close to significant in the hippocampus, but not in the other cerebral structures studied. In primary cultures of cerebellar neurons z-DEVD-fmk (2-50 microM) inhibited caspase-3 activity by 60-87%. We suggest that moderate inhibition of caspase-3 resulting from the central administration of z-DEVD-fmk to rats may impair active avoidance learning. Taking into account previous data on the involvement of neuronal caspase-3 in neuroplasticity phenomena we assume that the enzyme may be important for selected forms of learning.     

Inhibition of human rheumatoid arthritis synovial cell survival by hecogenin and tigogenin is associated with increased apoptosis, p38 mitogen-activated protein kinase activity and upregulation of cyclooxygenase-2

We conducted our study to assess the antiproliferative and proapoptotic potential of hecogenin and tigogenin, two saponins which are structurally similar to diosgenin. We particularly focused our attention on mitogen-activated protein kinase (MAPK) activation in relation to apoptosis but also with the COX-2 expression and activity. Rheumatoid arthritis (RA) synoviocytes were isolated from fresh synovial biopsies obtained from five RA patients undergoing hip arthroplasty. Measurement of cell proliferation was determined using the MTT assay. Apoptosis was evaluated by studying caspase-8, caspase-9 and caspase-3 activities but also by quantification of DNA fragmentation. Quantification of human phospho-MAPKs was realized by ELISA. COX-2 expression was demonstrated by Western blot analysis and COX-2 activity by assay of endogenous prostaglandin E2 (PGE2) production. Tigogenin was more effective than hecogenin in inducing apoptosis in human RA fibroblast-like synoviocytes (FLS) which was caspase dependent but poly(ADP-ribose) polymerase independent and characterized by DNA fragmentation. Our results demonstrated hecogenin- and tigogenin-induced apoptosis through activation of p38 without affecting the JNK and ERK pathways. Indeed, pretreatment with a p38 inhibitor decreased saponin-induced apoptosis with a significant decrease in DNA fragmentation. Furthermore, the rate of apoptosis induced by hecogenin or tigogenin was associated with overexpression of COX-2 correlated with overproduction of endogenous PGE2. These new results provide strong evidence that a family of structurally similar plant steroids is capable of inducing apoptosis in human RA FLS with different rates and different signalling pathways. This study also confirms the discussed appearance of the downregulation or upregulation of COX-2 in cell apoptosis as a function of cell type.     

Porcine reproductive and respiratory syndrome virus induces apoptosis through a mitochondria-mediated pathway

As with a number of other viruses, Porcine reproductive and respiratory syndrome virus (PRRSV) has been shown to induce apoptosis, although the mechanism(s) involved remain unknown. In this study we have characterized the apoptotic pathways activated by PRRSV infection. PRRSV-infected cells showed evidence of apoptosis including phosphatidylserine exposure, chromatin condensation, DNA fragmentation, caspase activation (including caspase-8, 9, 3), and PARP cleavage. DNA fragmentation was dependent on caspase activation but blocking apoptosis by a caspase inhibitor did not affect PRRSV replication. Upregulation of Bax expression by PRRSV infection was followed by disruption of the mitochondria transmembrane potential, resulting in cytochrome c redistridution to the cytoplasm and subsequent caspase-9 activation. A crosstalk between the extrinsic and intrinsic pathways was demonstrated by dependency of caspase-9 activation on active caspase-8 and by Bid cleavage. Furthermore, in this study we provide evidence of the possible involvement of reactive oxygen species (ROS)-mediated oxidative stress in apoptosis induced by PRRSV. Our data indicated that cell death caused by PRRSV infection involves necrosis as well as apoptosis. In summary, these findings demonstrate mechanisms by which PRRSV induces apoptosis and will contribute to an enhanced understanding of PRRSV pathogenesis.     

Cinobufagin exerts anti-proliferative and pro-apoptotic effects through the modulation ROS-mediated MAPKs signaling pathway

Abstract

Cinobufagin (CBG) is a cardiotoxic bufanolide steroid secreted by the skin and parotid venom glands of the Asiatic toad Bufo bufo gargarizans (called Chan-Su). Although CBG is known to exhibit anti-cancer activities, very little is known about its potential mechanism(s) of action. In this study, we investigated whether CBG mediates its effect through the modulation of the mitogen-activated protein kinases (MAPKs) signaling pathway in human multiple myeloma (MM) U266 cells. We found that CBG caused the significant activation of ERK, JNK and p38 MAPK in U266 cells. CBG showed much higher cytotoxicity against U266 cells as compared to peripheral blood mononuclear cells (PBMC). Induction of CBG increased reactive oxygen species (ROS) generation from mitochondria, which is associated with the induction of apoptosis as characterized by increased sub-G1 DNA contents of cell cycle, positive Annexin V binding, activation of caspase-3 and cleavage of PARP. Inhibition of ROS generation by N-acetyl-l-cysteine (NAC) significantly prevented CBG-induced ERK, JNK and p38 MAPK activation and apoptosis. CBG also down-regulated the expression of various downstream gene products that mediate cell proliferation, survival, angiogenesis and metastasis. Interestingly, ERK, JNK and p38MAPK pharmacological inhibitors blocked CBG-induced MAPKs activation and ERK inhibitor (PD98059) also prevented the CBG-induced caspase-3 activation and PARP cleavage in U266 cells. Taken together, these findings suggest that CBG can act as a potent anticancer agent against MM and possibly exerts its effects through the ROS-mediated activation of ERK, JNK and p38 MAPK leading to the activation of caspase-3 in U266 cells.     

Oridonin exhibits anti-angiogenic activity in human umbilical vein endothelial cells by inhibiting VEGF-induced VEGFR-2 signaling pathway

Oridonin has been found to be a potential anti-angiogenesis agent. However, its functional targets and the underlying mechanisms are still vague. In vitro studies we found that oridonin not only inhibited VEGF-induced cell proliferation, migration and tube formation but also caused G2/M phase arrest and triggered cellular apoptosis in HUVECs. In mechanistic studies revealed that oridonin exhibited the anti-angiogenic potency, at least in part, through the down-regulation of VEGFR2-mediated FAK/MMPs, mTOR/PI3K/Akt and ERK/p38 signaling pathways which led to reduced invasion, migration, and tube formation in HUVECs. Our results could provide evidence that oridonin exerts strong anti-angiogenesis activities via specifically targeting VEGFR2 and its signaling pathway.     

冬凌草甲素对急性白血病HL-60细胞的增殖抑制作用及其作用机制

目的探讨冬凌草甲素对急性白血病HL-60细胞的增殖抑制作用及其作用机制。方法以不同浓度的冬凌草甲素作用于体外培养的HL-60细胞，MTr法检测细胞生长抑制率，应用流式细胞仪检测细胞凋亡情况，瑞氏染色法观察细胞凋亡时的形态学变化。应用PCR．ELISA及RT—PCR法检测细胞凋亡前后端粒酶活性及端粒酶hTERT mRNA表达水平的变化。结果冬凌草甲素可显著的抑制HL-60细胞的生长，诱导细胞发生凋亡，并呈现出明显的量-与时-效关系。冬凌草甲素作用48—60h后在瑞氏染色图片上可见核浓缩及核碎裂等典型的细胞凋亡特征，同时端粒酶hTERT mRNA的表达水平及端粒酶活性均明显降低。结论冬凌草甲素能抑制HL-60细胞的生长及诱导细胞发生凋亡：降低端粒酶hTERT mRNA的表达水平及端粒酶活性可能是其重要作用机制之一。