Caspase-3在roscovitine诱发PC12细胞凋亡中发挥重要作用

我们已证实周期蛋白激酶（cyclin-dependent kinases）cdk2、cdc2和cdk5抑制剂roscovitine诱导PC12细胞凋亡。本实验应用caspase-3免疫细胞化学与hoechst 33342荧光化学双标、MTT比色法细胞活性测定和Western blot方法,研究了caspase-3在roscovitine所致PC12细胞凋亡中的作用。结果显示,roscovitine（50μmol／L）处理PC12细胞12h,细胞核染色质凝缩及核碎片形成,同时胞浆中出现caspase-3阳性标志,caspase-3阳性细胞占细胞总数的42％。非特异性caspases抑制剂Z-VAD-FMK（50μmol／L）和caspase-3特异性抑制剂Z-DEVD-FMK（100μmol／L）可部分降低roscovitine所致的细胞死亡,使细胞存活率分别由29．03％（roscovitine）增至58．06％（Z-VAD-FMK＋roscovitine）和45．16％（Z-DEVD-FMK＋roscovitine）：用单克隆non-erythroid α-spectrin抗体检测roscovitine处理组细胞匀浆提取液,表明caspase-3裂解的特异性spectfin 120kDa蛋白产物较对照组显著增加。提示细胞凋亡成分caspases参与roscovitine所敛的细胞凋亡,其中caspase-3发挥重要作用。     

Thapsigargin increases apoptotic cell death in human hepatoma BEL—7404 cells

Effects of thapsigargin,an inhibitor of Ca^2 -ATPase in surface of endoplasmic reticulum,on apoptotic cell death were studied in human hepatoma cells of BEL-7404 cell line by using both flow cytometry and electron microscopy.Propidium iodide staining and flow cytometry revealed that in the serum-free condition,thapsigargin increased the rate of apoptosis of BEL-7404 cells in a dose-dependent manner.Prolongation of the period of serum-free condition enhanced the apoptosis induced by thapsigargin treatment.Morphological observation with electron microscope further demonstrated that chromatin condensation and fragmentation,apoptotic bodies existed in TG-treated cells,supporting that thapsigargin is a potent activator of apoptosis in the cells.     

Irisin induces trophoblast differentiation via AMPK activation in the human placenta

Irisin, an adipokine, regulates differentiation and phenotype in various cell types including myocytes, adipocytes, and osteoblasts. Circulating irisin concentration increases throughout human pregnancy. In pregnancy disorders such as preeclampsia and gestational diabetes mellitus, circulating irisin levels are reduced compared to healthy controls. To date, there are no data on the role and molecular function of irisin in the human placenta or its contribution to pathophysiology. Aberrant trophoblast differentiation is involved in the pathophysiology of preeclampsia. The current study aimed to assess the molecular effects of irisin on trophoblast differentiation and function. First-trimester placental explants were cultured and treated with low (10 nM) and high (50 nM) physiological doses of irisin. Treatment with irisin dose-dependently increased both in vitro placental outgrowth (on Matrigel™) and trophoblast cell-cell fusion. Adenosine monophosphate-activated protein kinase (AMPK) signaling, an important regulator of cellular energy homeostasis that is involved in trophoblast differentiation and pathology, was subsequently investigated. Here, irisin exposure induced placental AMPK activation. To determine the effects of irisin on trophoblast differentiation, two trophoblast-like cell lines, HTR-8/SVneo and BeWo, were treated with irisin and/or a specific AMPK inhibitor (Compound C). Irisin-induced AMPK phosphorylation in HTR-8/SVneo cells. Additionally, as part of the differentiation process, integrin switching from α6 to α1 occurred as well as increased invasiveness. Overall, irisin promoted differentiation in villous and extravillous cell-based models via AMPK pathway activation. These findings provide evidence that exposure to irisin promotes differentiation and improves trophoblast functions in the human placenta that are affected in abnormal placentation.     

Inhibition of JNK2 and JNK3 by JNK inhibitor IX induces prometaphase arrest-dependent apoptotic cell death in human Jurkat T cells

Exposure of human Jurkat T cells to JNK inhibitor IX (JNKi), targeting JNK2 and JNK3, caused apoptotic DNA fragmentation along with G₂/M arrest, phosphorylation of Bcl-2, Mcl-1, and Bim, Δψm loss, and activation of Bak and caspase cascade. These JNKi-induced apoptotic events were abrogated by Bcl-2 overexpression, whereas G₂/M arrest, cyclin B1 up-regulation, Cdk1 activation, and phosphorylation of Bcl-2 family proteins were sustained. In the concomitant presence of the G₁/S blocking agent aphidicolin and JNKi, the cells underwent G₁/S arrest and failed to induce all apoptotic events. The JNKi-induced phosphorylation of Bcl-2 family proteins and mitochondrial apoptotic events were suppressed by the Cdk1 inhibitor. Immunofluorescence microscopic analysis revealed that mitotic spindle defect and prometaphase arrest were the underlying factors for the G₂/M arrest. These results demonstrate that JNKi-induced mitochondrial apoptosis was caused by microtubule damage-mediated prometaphase arrest, prolonged Cdk1 activation, and phosphorylation of Bcl-2 family proteins in Jurkat T cells.     

2-methoxyestradiol-induced cell death in osteosarcoma cells is preceded by cell cycle arrest

2-Methoxyestradiol (2-ME), a naturally occurring mammalian metabolite of 17beta-Estradiol (E2), induces cell death in osteosarcoma cells. To further understand the molecular mechanisms of action, we have investigated cell cycle progression in 2-ME-treated human osteosarcoma (MG63, SaOS-2 and LM7 [corrected]) cells. At 5 microM, 2-ME induced growth arrest by inducing a block in cell cycle; 2-ME-treatment resulted in 2-fold increases in G1 phase cells and a decrease in S phase cells in MG63 and SaOS-2 osteosarcoma cell lines, compared to the appropriate vehicle controls. 2-ME-treatment induced a threefold increase in the G2 phase in LM7 [corrected] osteosarcoma cells. The results demonstrated steroid specificity, as the tumorigenic metabolite, 16alpha-hydroxyestradiol (16-OHE), did not have any effect on cell cycle progression in osteosarcoma cells. The cell cycle arrest coincided with an increase in expression of the cell cycle markers p21, p27 and p53 proteins in 2-ME-treated osteosarcoma cells. Also, MG63 cells, transiently transfected with cDNA for a 'loss of function mutant' RNA-dependent protein kinase (PKR) protein, were resistant to 2-ME-induced cell cycle arrest. These results suggest that 2-ME works in concert with factors regulating cell cycle progression, and cell cycle arrest precedes cell death in 2-ME-treated osteosarcoma cells.     

4-Deoxyraputindole C induces cell death and cell cycle arrest in tumor cell lines

Several molecules extracted from natural products exhibit different biological activities, such as ion channel modulation, activation of signaling pathways, and anti-inflammatory or antitumor activity. In this study, we tested the antitumor ability of natural compounds extracted from the Raputia praetermissa plant. Among the compounds tested, an alkaloid, here called compound S4 (4-Deoxyraputindole C), showed antitumor effects against human tumor lineages. Compound S4 was the most active against Raji, a lymphoma lineage, promoting cell death with characteristics that including membrane permeabilization, dissipation of the mitochondrial potential, increased superoxide production, and lysosomal membrane permeabilization. The use of cell death inhibitors such as Z-VAD-FMK (caspase inhibitor), necrostatin-1 (receptor-interacting serine/threonine-protein kinase 1 inhibitor), E-64 (cysteine peptidases inhibitor), and N-acetyl- L -cysteine (antioxidant) did not decrease compound S4-dependent cell death. Additionally, we tested the effect of cellular activity on adherent human tumor cells. The highest reduction of cellular activity was observed in A549 cells, a lung carcinoma lineage. In this lineage, the effect on the reduction of the cellular activity was due to cell cycle arrest, without plasma membrane permeabilization, loss of the mitochondrial potential or lysosomal membrane permeabilization. Compound S4 was able to inhibit cathepsin B and L by a nonlinear competitive (negative co-operativity) and simple-linear competitive inhibitions, respectively. The potency of inhibition was higher against cathepsin L. Compound S4 promoted cell cycle arrest at G ₀ and G ₂ phase, and increase the expression of p16 and p21 proteins. In conclusion, compound S4 is an interesting molecule against cancer, promoting cell death in the human lymphoma lineage Raji and cell cycle arrest in the human lung carcinoma lineage A549.     

Homocysteine-thiolactone induces caspase-independent vascular endothelial cell death with apoptotic features

Objective. Cell death is generally classified into two large categories: apoptosis, which represents active, physiological programmed cell death, and necrosis, which represents passive cell death without underlying regulatory mechanisms. Apoptosis plays an important role in tissue homeostasis and its role in endothelium integrity can be influenced by the functional status of endothelial cells. Homocysteine, a sulfated amino-acid product of methionine demethylation, is an independent risk factor for vascular disease (arterial and venous thombosis). Our goal was to investigate the thiol-derivatives effect on the endothelial cell apoptosis. Methods. Three parameters were measured: mitochondrial membrane potential using DiOC₆(3) as the probe, DEVDase activation, and phosphatidylserine exposure on the cell surface with fluorosceinated annexin V labeling which allows apoptosis to be distinguished from necrosis. Results. Homocysteine-thiolactone induced endothelial cell apoptosis in a concentration-dependent manner (range: 50–200 M), independently of the caspase pathway. Only homocysteine-thiolactone, among the thiol derivatives tested, induced apoptosis. Apoptosis was not influenced by the serum concentration in culture medium, suggesting that the observed apoptotic process could occur in vivo. None of the inhibitors used (e.g., leupeptin, fumosinin Bl, catalase, or z-VAD-fmk) was able to prevent homocysteine-induced apoptosis of vascular endothelial cells. Conclusion. The apoptosis of vascular endothelial cells induced by high concentration of homocysteine-thiolactone might be one step atherosclerotic cardiovascular disease, and contribute to its complication.     

Genipin induces cell death via intrinsic apoptosis pathways in human glioblastoma cells

Genipin, a compound derived from Gardenis jasminoides Ellis fruits, was demonstrated to be the specific uncoupling protein 2 (UCP2) inhibitor. UCP2 is a mitochondrial carrier protein that creates proton leaks across the inner mitochondrial membrane, thus uncoupling oxidative phosphorylation from adenosine triphosphate (ATP) synthesis. Several studies revealed that UCP2 is broadly over-expressed in leukemia, colorectal, lung, ovarian, prostate, testicular, and bladder cancers. However, the effect of genipin still needs to be elucidated in neurological malignancies. In this study, we investigated the anticancer effect of genipin in U87MG and A172 cell lines. The anticancer effect of genipin on these cell lines was measured by microculture tetrazoliumtest (MTT), Trypan blue exclusion, and colony formation assays, in the presence of various concentrations of genipin at different time intervals. We assessed apoptosis and measure intracellular reactive oxygen species (ROS) by flow cytometry. Expression of UCP2 and some of the genes involved in apoptosis was analyzed by real-time quantitative polymerase chain reaction (PCR). Results of the MTT assay showed that genipin moderately reduced metabolic activity of both cell lines in dose- and time-dependent manner. Result of Trypan blue exclusion test indicated that the viable cell count decreased in the treated group in a concentration-dependent manner. Genipin also significantly decreased colony formation ability of these cells in a concentration-dependent manner. Result of morphological changes showed that there were significant differences in cell number and morphology in treated groups as compared with the untreated groups. Flow cytometric analysis of U87MG and A172 cells with annexin V/propidium iodide staining, 48 hours after treatment with genipin, displays 22.4% and 26.1% apoptotic population, respectively, in treated cells, in comparison to 7.42% and 9.31% apoptotic cells of untreated cells. After treatment, UCP2 and B-cell lymphoma 2 (BCL ₂) genes are downregulated, and BCL ₂ associated X protein, BCL ₂ antagonist/killer, BCL ₂ interacting killer, and Cytochrome c genes are upregulated. Genipin treatment increased mitochondrial ROS levels and also induced apoptosis through caspase-3 upregulation. In conclusion, the antiproliferative effects of genipin on the growth of both glioblastoma cell lines have been shown in all of these assays, and genipin profoundly induced apoptosis in both cell lines via the UCP2-related mitochondrial pathway through the induction of intracellular ROS.     

Manganese(II) induces apoptotic cell death in NIH3T3 cells via a caspase-12-dependent pathway

Under physiological conditions, manganese(II) exhibits catalase-like activity. However, at elevated concentrations, it induces apoptosis via a non-mitochondria-mediated mechanism (Oubrahim, H., Stadtman, E. R., and Chock, P. B. (2001) Proc. Natl. Acad. Sci. U. S. A. 98, 9505-9510). In this study, we show that the Mn(II)-induced apoptosis, as monitored by caspase-3-like activity, in NIH3T3 cells was inhibited by calpain inhibitors I and II or the p38 MAP kinase inhibitor, SB202190. The control experiments showed that each of these inhibitors in the concentration ranges used exerted no effect on activated caspase-3-like activity. Furthermore, caspase-12 was cleaved in Mn(II)-treated cells, suggesting that the Mn(II)-induced apoptosis is mediated by caspase-12. This notion is confirmed by the observations that pretreatment of NIH3T3 cells with either caspase-12 antisense RNA or dsRNA corresponding to the full-length caspase-12 led to a dramatic decrease in caspase-3-like activity induced by Mn(II). The precise mechanism by which Mn(II) induced the apoptosis is not clear. Nevertheless, Mn(II), in part, exerts its effect via its ability to replace Ca(II) in the activation of m-calpain, which in turn activates caspase-12 and degrades Bcl-xL. In addition, the dsRNA(i) method serves as an effective technique for knocking out caspase-12 in NIH3T3 cells without causing apoptosis.     

EphrinA5-EphA7 complex induces apoptotic cell death via TNFR1

A previous study showed that the EphA7 receptor regulates apoptotic cell death during early brain development. In this study, we provide evidence that the EphA7 receptor interacts with death receptors such as tumor necrosis factor receptor 1 (TNFR1) to decrease cell viability. We showed that ephrinA5 stimulates EphA7 to activate the TNFR1-mediated apoptotic signaling pathway. In addition, a pull-down assay using biotinylated ephrinA5-Fc revealed that ephrinA5-EphA7 complexes recruit TNFR1 to form a multi-protein complex. Immunocytochemical staining analysis showed that EphA7 was co-localized with TNFR1 on the cell surface when cells were incubated with ephrinA5 at low temperatures. Finally, both the internalization motif and death domain of TNFR1 was important for interacting with an intracytoplasmic region of EphA7; this interaction was essential for inducing the apoptotic signaling cascade. This result suggests that a distinct multi-protein complex comprising ephrinA5, EphA7, and TNFR1 may constitute a platform for inducing caspase-dependent apoptotic cell death.     

Tomentosin induces apoptotic pathway by blocking inflammatory mediators via modulation of cell proteins in AGS gastric cancer cell line

In this study, we investigated the in vitro effect of tomentosin on cell proliferation by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay, reactive oxygen species by 2′,7′‐dichlorofluorescein diacetate staining assay, apoptosis (AO/EtBr, propidium iodide, and 4′,6‐diamidino‐2‐phenylindole staining, mitochondrial membrane potential), cell adherent, cell migration, inflammation, apoptosis, and oxidative stress from gastric cancer cells (GCCs) AGS. Upon their relative cell proliferative, inflammatory, and apoptotic molecular markers were analyzed by using the enzyme‐linked immunosorbent assay and Western blot analysis method. Treatment with tomentosin (IC₅₀ = 20 µM) significantly inhibited cell proliferation and oxidative stress‐induced anti‐cell proliferative (proliferating cell nuclear antigen and cyclin‐D1) also regulated expression, drastically diminished tumor necrosis factor‐α, nuclear factor‐κB, interleukin‐6, and interleukin‐1β expression levels, significantly upregulated Bcl‐2 and Bax expression. Thus, this tomentosin can significantly reduce GCC proliferation via cytotoxicity which is stimulated apoptosis markers via morphology staining changes and inhibitory inflammatory markers. The tomentosin‐induced oxidative stress may be involved to stimulate apoptotic mechanisms via mitochondria‐mediated signaling by the inhibition of inflammation. Taken together, our findings suggest a possible future use of chemotherapeutic agents for pharmacological benefits and as an anti‐cancer treatment option.     

Crosstalk between elicitor-induced cell death and cell cycle regulation in tobacco BY-2 cells

The molecular links between cell cycle control and the regulation of programmed cell death are largely unknown in plants. Here we studied the relationship between the cell cycle and elicitor-induced cell death using synchronized tobacco BY-2 cells. Flow cytometry and fluorescence microscopy of nuclear DNA, and RNA gel-blot analyses of cell cycle-related genes revealed that the proteinaceous elicitor cryptogein induced cell cycle arrest at the G1 or G2 phase before the induction of cell death. Furthermore, the patterns of cell death induction and defence-related genes were different in different phases of the cell cycle. Constitutive treatment with cryptogein induced cell cycle arrest and cell death at the G1 or G2 phase. With transient treatment for 2 h, cell cycle arrest and cell death were only induced by treatment with the elicitor during the S or G1 phase. By contrast, the elicitor-induced production of reactive oxygen species was observed during all phases of the cell cycle. These results indicate that although recognition of the elicitor signal is cell cycle-independent, the induction of cell cycle arrest and cell death depends on the phase of the cell cycle.     

Induction of programmed cell death in human retinoblastoma Y79 cells by C2-ceramide

C₂-ceramide, a cell-permeable analogue of ceramide, induced significant, dose- and time-dependent death in human retinoblastoma Y79 cells. Dying cells strongly displayed the morphology of apoptosis as characterized by microscopic evidence of cell shrinkage, membrane blebbing, nuclear and chromatin condensation and degeneration of the nucleus into membrane-bound apoptotic bodies. Upon induction of apoptosis Y79 cells evidence early phosphatidylserine externalization, as shown by annexin V-FITC. Apoptosis was also assessed by monitoring changes in cell granularity by staining with the combined fluorescent dyes acridine orange and ethidium bromide. C₂-ceramide induced these morphological changes without a concomitant production of oligonucleosomal fragments responsible for the DNA ladder and without changes in p53 protein level. Apoptosis was accompanied by accumulation of a modified Bcl-2 protein with a slower-mobility form, and by proteolytic cleavage of PARP. The effect seemed to be specific for C₂-ceramide, as C₂-dihydroceramide, or other amphiphilic lipid analogues, or products of ceramide hydrolysis were ineffective. The effect also depended on mRNA and protein synthesis as it was markedly inhibited by actinomycin D and cycloheximide. Sphingomyelinase and interleukin-l, which are known to activate the sphingomyelin turnover leading to ceramide generation, also induced apoptosis mimicking the effects of ceramide. These findings propose ceramide as an activator of the suicidal program in Y79 cells.     

Daunorubicin induces cell death via activation of apoptotic signalling pathway and inactivation of survival pathway in muscle-derived stem cells

Daunorubicin (as well as other anthracyclines) is known to be toxic to heart cells and other cells in organism thus limiting its applicability in human cancer therapy. To investigate possible mechanisms of daunorubicin cytotoxicity, we used stem cell lines derived from adult rabbit skeletal muscle. Recently, we have shown that daunorubicin induces apoptotic cell death in our cell model system and distinctly influences the activity of MAP kinases. Here, we demonstrate that two widely accepted antagonistic signalling pathways namely proapoptotic JNK and prosurvival PI3K/AKT participate in apoptosis. Using the Western blot method, we observed the activation of JNK and phosphorylation of its direct target c-Jun along with inactivation of AKT and its direct target GSK in the course of programmed cell death. By means of small-molecule kinase inhibitors and transfection of cells with the genes of the components of these pathways, c-Jun and AKT, we confirm that JNK signalling pathway is proapoptotic, whereas AKT is antiapoptotic in daunorubicin-induced muscle cells. These findings could contribute to new approaches which will result in less toxicity and fewer side effects that are currently associated with the use of daunorubicin in cancer therapies.     

Calcium fluxes in human trophoblast (BeWo) cells: calcium channels,calcium-ATPase,and sodium-calcium exchanger expression

Although placental transfer of maternal calcium (Ca(2+)) is a crucial process for fetal development, the biochemical mechanisms are poorly understood. In the current study, we have investigated the characteristics of Ca(2+) fluxes in relation with cell Ca(2+) homeostasis in the human placental trophoblast cell line BeWo. Time-courses of Ca(2+) uptake by BeWo cells displayed rapid initial entry (initial velocity (V(i)) of 3.42 +/- 0.35 nmol/mg protein/min) and subsequent establishment of a plateau. Ca(2+) efflux studies with (45)Ca(2+)-loaded cells also showed rapid declined of cell-associated (45)Ca(2+) with a V(i) of efflux (Ve(i)) of 3.30 +/- 0.08 nmol/mg protein/min. Further identification of membrane gates for Ca(2+) entry in BeWo cells was carried out. Expression of Ca(2+) transporter/channel CaT1 and L-type alpha(1S) subunit was showed by RT-PCR. However, mRNA for CaT2 channel and L-type alpha(1C) and alpha(1D) subunits were not revealed. Membrane systems responsible for intracellular Ca(2+) extrusion from BeWo cells were also investigated. Plasma membrane Ca(2+)-ATPases (PMCA) and Na/Ca exchangers (NCX) were detected by Western blot in BeWo cells. Expression of specific isoforms of PMCA and NCX was further investigated by RT-PCR. Messenger RNAs of four isoforms of PMCA (PMCA 1-4) were detected. The presence of messenger RNAs of two NCX isoforms (NCX1 and NCX3) was observed. Ca(2+) flux studies in Na-free incubation medium indicated that NCX played a minimal role in the cell Ca(2+) fluxes. Inorganic ions such as cadmium and manganese did not modify the Ca(2+) fluxes, however, barium increased cell-associated (45)Ca(2+) by, in part, by reducing radiolabel exit.