benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone and pyrazolanthrone

Oxymatrine (OMT) often used in treatment for chronic hepatitis B virus infection in clinic. However, OMT-induced liver injury has been reported. In this study, we aim to investigate the possible mechanism of OMT-induced hepatotoxicity in human normal liver cells (L02). Exposed cells to OMT, the cell viability was decreased and apoptosis rate increased, the intracellular markers of oxidative stress were changed. Simultaneously, OMT altered apoptotic related proteins levels, including Bcl-2, Bax and pro-caspase-8/-9/-3. In addition, OMT enhanced the protein levels of endoplasmic reticulum (ER) stress makers (GRP78/Bip, CHOP, and cleaved-Caspase-4) and phosphorylation of c-Jun N-terminal kinase (p-JNK), as well as the mRNA levels of GRP78/Bip, CHOP, caspase-4, and ER stress sensors (IREI, ATF6, and PERK). Pre-treatment with Z-VAD-fmk, JNK inhibitor SP600125 and N-acetyl-l-cysteine (NAC), a ROS scavenger, partly improved the survival rates and restored OMT-induced cellular damage, and reduced caspase-3 cleavage. SP600125 or NAC reduced OMT-induced p-JNK and NAC significantly lowered caspase-4. Furthermore, 4-PBA, the ER stress inhibitor, weakened inhibitory effect of OMT on cells, on the contrary, TM worsen. 4-PBA also reduced the levels of p-JNK and cleaved-caspase-3 proteins. Therefore, OMT-induced injury in L02 cells was related to ROS mediated p-JNK and ER stress induction. Antioxidant, by inhibition of p-JNK or ER stress, may be a feasible method to alleviate OMT-induced liver injury.

Topics: Acetylcysteine; Alkaloids; Amino Acid Chloromethyl Ketones; Anthracenes; Antioxidants; Antiviral Agents; Apoptosis; Butylamines; Cell Line; Chemical and Drug Induced Liver Injury; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Free Radical Scavengers; Gene Expression Regulation; Hepatocytes; Humans; JNK Mitogen-Activated Protein Kinases; Phosphorylation; Protein Processing, Post-Translational; Quinolizines; Reactive Oxygen Species

Incidents associated with methanol intoxication resulting from the consumption of fake wine occur not infrequently worldwide. Certain individuals are made blind due to methanol poisoning. The present study aimed to investigate the effects of sodium formate exposure on photoreceptor cells (661W cells). The 661W cells were exposed to sodium formate for 6‑24 h and cell viability was determined using a 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyl‑2H‑tetrazolium bromide (MTT) assay. Subsequently, the 661W cells were exposed to 15 or 30 mM sodium formate for 24 h. The level of apoptosis was determined using Hoechst 33342/propidium iodide staining, visualizing the cells under a fluorescence microscope, and annexin V‑fluorescein isothiocyanate staining, using flow cytometric analysis. Intracellular reactive oxygen species (ROS) were measured using 2',7'‑dichlorofluorescein diacetate (DCFH‑DA) staining, followed by flow cytometric analysis. Autophagy of the 661W cells was measured by monodansylcadaverine staining. The activation of phosphorylated c‑Jun N‑terminal kinase (p‑JNK), B‑cell lymphoma (Bcl‑2), Bcl‑2‑associated X protein, cleaved caspase‑3, cleaved caspase‑9 and microtubule‑associated protein 1A/1B‑light chain 3 (LC3) was assessed by western blotting. The effects of Z‑VAD‑fmk (a pan‑caspase inhibitor) and SP600125 (a JNK inhibitor) on the viability of the sodium formate‑induced 661W cells were determined using an MTT assay. Sodium formate treatment induced a decrease in the viability of the 661W cells in a time‑ and a dose‑dependent manner. In addition, sodium formate at concentrations of 15 or 30 mM markedly increased the level of apoptosis and the ROS levels, as measured by DCFH‑DA staining of the 661W cells. Additionally, 661W cells exposed to sodium formate for 24 h exhibited increased levels of p‑JNK, Bax, cleaved caspase‑3, cleaved caspase‑9 and LC3II (the phosphatidylethanolamine‑modified form of LC3), although the level of Bcl‑2 was decreased. Furthermore, cell cytotoxicity and autophagy were induced upon treatment with sodium formate. Z‑VAD‑fmk and SP600125 were able to effectively circumvent the effects of sodium formate on cell viability. These results suggested that the cytotoxicity induced by sodium formate induces the activation of the JNK signaling pathway, leading to caspase‑dependent apoptosis. Increased levels of autophagy were also observed during the process of 661W cell damage induced by sodium formate.

Topics: Amino Acid Chloromethyl Ketones; Anthracenes; Apoptosis; Autophagy; bcl-2-Associated X Protein; Caspases; Cell Line, Tumor; Cell Survival; Enzyme Activation; Formates; Humans; Intracellular Space; JNK Mitogen-Activated Protein Kinases; MAP Kinase Signaling System; Microtubule-Associated Proteins; Photoreceptor Cells; Reactive Oxygen Species; Staining and Labeling

Tubeimoside-1 (TBMS1), a triterpenoid saponin extracted from the Chinese herbal medicine Bolbostemma paniculatum (Maxim) Franquet (Cucurbitaceae), has shown anticancer activities in various cancer cell lines. The aim of this study was to investigate the anticancer activity and molecular targets of TBMS1 in human prostate cancer cells in vitro.. DU145 and P3 human prostate cancer cells were treated with TBMS1. Cell viability and apoptosis were detected. ROS generation, mitochondrial membrane potential and cell cycle profile were examined. Western blotting was used to measure the expression of relevant proteins in the cells.. TBMS1 (5-100 μmol/L) significantly suppressed the viability of DU145 and P3 cells with IC50 values of approximately 10 and 20 μmol/L, respectively. Furthermore, TBMS1 dose-dependently induced apoptosis and cell cycle arrest at G0/G1 phase in DU145 and P3 cells. In DU145 cells, TBMS1 induced mitochondrial apoptosis, evidenced by ROS generation, mitochondrial dysfunction, endoplasmic reticulum stress, modulated Bcl-2 family protein and cleaved caspase-3, and activated ASK-1 and its downstream targets p38 and JNK. The G0/G1 phase arrest was linked to increased expression of p53 and p21 and decreased expression of cyclin E and cdk2. Co-treatment with Z-VAD-FMK (pan-caspase inhibitor) could attenuate TBMS1-induced apoptosis but did not prevent G0/G1 arrest. Moreover, co-treatment with NAC (ROS scavenger), SB203580 (p38 inhibitor), SP600125 (JNK inhibitor) or salubrinal (ER stress inhibitor) significantly attenuated TBMS1-induced apoptosis.. TBMS1 induces oxidative stress-mediated apoptosis in DU145 human prostate cancer cells in vitro via the mitochondrial pathway.

Topics: Acetylcysteine; Amino Acid Chloromethyl Ketones; Anthracenes; Apoptosis; Caspase 3; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Survival; Cinnamates; Cyclin E; Cyclin-Dependent Kinase 2; Dose-Response Relationship, Drug; Endoplasmic Reticulum Stress; G1 Phase; Humans; Imidazoles; JNK Mitogen-Activated Protein Kinases; Male; MAP Kinase Kinase Kinase 5; Membrane Potential, Mitochondrial; Oxidative Stress; p38 Mitogen-Activated Protein Kinases; Prostatic Neoplasms; Proto-Oncogene Proteins c-bcl-2; Pyridines; Reactive Oxygen Species; Resting Phase, Cell Cycle; Saponins; Thiourea; Triterpenes

Retinal pigment epithelial (RPE) cells form a blood-ocular barrier, and their polarized property is crucial for maintaining the barrier functions. Tumor necrosis factor alpha (TNF-α), a major pleotropic inflammatory cytokine that disrupts the barrier function and eventual angiogenesis, is expressed in the choroidal neovascularizations of age-related macular degeneration eyes. Thus, it most likely plays an important role in the progression of the disease. The purpose of this study was to compare the effects of TNF-α on the barrier function of polarized RPE cells. Non-polarized RPE cells were used as negative controls. Isolated porcine RPE cells were seeded on Transwell™ membranes. The polarization of the RPE cells was determined by their high transepithelial electrical resistance (TER >150 Ω cm(2)) and by their differential secretion of vascular endothelial growth factor (lower layer/upper layer >2.5X). Polarized RPE cells were incubated with 10 ng/ml of TNF-α and the TER was measured. TNF-α significantly decreased the TER of polarized RPE cells by 17.6 ± 2.7% (P < 0.001) of the control at 24 h and that of non-polarized RPE cells by 5.4 ± 6.5% (P = 0.401). The p38 mitogen-activated protein kinase (MAPK) inhibitor, SB203580, blocked the effects of TNF-α of decreasing the TER. Cell junction-related molecules, e.g., ZO-1, located between cells in control RPE cells, were disassembled by TNF-α, and this breakdown was suppressed by SB203580 in polarized RPEs. These results indicate that the breakdown of the RPE barrier function was caused exclusively by TNF-α in polarized RPEs, and TNF-α was acting through the p38 MAPK pathways. Investigations of polarized RPE cells should be more suitable for in vitro studies of the pathophysiology of retinochoroidal diseases.

Topics: Amino Acid Chloromethyl Ketones; Animals; Anthracenes; Blood-Retinal Barrier; Blotting, Western; Cell Polarity; Cells, Cultured; Electric Impedance; Enzyme Inhibitors; Enzyme-Linked Immunosorbent Assay; Imidazoles; In Situ Nick-End Labeling; Microscopy, Electron, Scanning; p38 Mitogen-Activated Protein Kinases; Pyridines; Recombinant Proteins; Retinal Pigment Epithelium; Swine; Tight Junction Proteins; Tight Junctions; Tumor Necrosis Factor-alpha; Vascular Endothelial Growth Factor A

Evidence suggests that mistletoe extract has the potential to be used as an anticancer agent. Abnobaviscum F® is a European mistletoe extract from the host tree Fraxinus. We investigated the effect of Abnobaviscum F on the growth and survival of different leukemia cell lines. Abnobaviscum F treatment strongly reduced survival and induced apoptosis of K562 (human myeloid leukemia), RPMI-8226 (human plasmacytoma) and L1210 (murine lymphocytic leukemia) cells in culture. Using K562 cells to further investigate the mechanism of action of Abnobaviscum F, we showed that Abnobaviscum F-induced cell death was associated with the activation of caspase-9, JNK-1/2 and p38 MAPK, as well as with the downregulation of Mcl-1, and inhibition of ERK-1/2 and PKB phosphorylation. Moreover, Abnobaviscum F treatment led to both a reduction of cellular glutathione (GSH) and the induction of ER stress (GRP78 and CHOP induction and eIF-2α phosphorylation). By contrast, Abnobaviscum F did not impact the expression of the DR4 and DR5 death receptors. The Abnobaviscum F-induced apoptosis of K562 cells was blocked by pretreatment with either GSH, z-VAD-fmk or SP600125. Our results, therefore, show that Abnobaviscum F induces apoptosis of K562 cells through the activation of the intrinsic caspase pathway, the phosphorylation of JNK-1, the reduction of cellular GSH, and the induction of ER stress.

Topics: Amino Acid Chloromethyl Ketones; Animals; Anthracenes; Apoptosis; Caspase 9; Cell Line, Tumor; DNA Fragmentation; Down-Regulation; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Eukaryotic Initiation Factor-2; Extracellular Signal-Regulated MAP Kinases; Glutathione; Heat-Shock Proteins; Humans; JNK Mitogen-Activated Protein Kinases; K562 Cells; Leukemia, Lymphoid; Leukemia, Myeloid; Mice; Myeloid Cell Leukemia Sequence 1 Protein; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Plant Extracts; Plasmacytoma; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; Receptors, TNF-Related Apoptosis-Inducing Ligand; Transcription Factor CHOP; Viscum album

Okadaic acid (OA) is a specific and potent protein phosphatase inhibitor and tumor promoter. The present study establishes the role of reactive oxygen species (ROS) and mitogen activated protein kinases in cell death induced by okadaic acid. The study showed that okadaic acid is cytotoxic at 10 nM with an IC50 of 100 nM in U-937 cells. The CVDE assay and mitochondrial dehydrogenase assay showed a time dependent cytotoxicity. The phase contrast visualization of the OA treated cells showed the apoptotic morphology and was confirmed with esterase staining for plasma membrane integrity. OA activated caspases-7, 9 and 3, PARP cleavage and induced nuclear damage in a time and dose dependent manner. Compromised mitochondrial membrane potential, release of cytochrome-c and apoptosis inducing factor confirms the involvement of mitochondria. A time dependent decrease in glutathione levels and a dose dependent increase in ROS with maximum at 30 min were observed. ROS scavenger-N-acetyl cysteine, mitochondrial stabilizer-cyclosporin-A, and broad spectrum caspase inhibitor Z-VAD-FMK inhibited the OA induced caspase-3 activation, DNA damage and cell death but caspase-8 inhibitor had no effect. OA activated p38 MAPK and JNK in a time dependent manner, but not ERK½. MAP kinase inhibitors SB203580, SP600125 and PD98059 confirm the role of p38 MAPK and JNK in OA induced caspase-3 activation and cell death. Over all, our results indicate that OA induces cell death by generation of ROS, and activation of p38 MAPK and JNK, and executed through mitochondrial mediated caspase pathway.

Topics: Acetylcysteine; Amino Acid Chloromethyl Ketones; Anthracenes; Apoptosis; Apoptosis Inducing Factor; Blotting, Western; Caspase 3; Caspase 7; Caspase 9; Cell Line, Tumor; Cyclosporins; Cytochromes c; DNA Damage; Extracellular Signal-Regulated MAP Kinases; Flavonoids; Glutathione; Humans; Imidazoles; Immunoblotting; JNK Mitogen-Activated Protein Kinases; MAP Kinase Signaling System; Membrane Potential, Mitochondrial; Mitochondria; Okadaic Acid; p38 Mitogen-Activated Protein Kinases; Poly(ADP-ribose) Polymerases; Pyridines; Reactive Oxygen Species; U937 Cells

TNF-alpha has recently been implicated in diabetic nephropathy, which is usually accompanied by higher sodium retention. The kidneys play a major role in sodium homeostasis by regulating tubular sodium reabsorption, a process geared by the sodium gradient established by the Na(+)/K(+) ATPase. The aim of this work was to investigate the effect of TNF on the ATPase, and consequently its implication in kidney malfunction, using LLC-PK1 cells. The cytokine reduced the Na(+)/K(+)ATPase activity significantly. In an attempt to elucidate the signalling pathway involved, PDTC (pyrrolidinedithiocarbamate), SP600125 and FK009 respectively inhibitors of NF-kappaB, c-JNK and caspases, were added to the cells in the presence and absence of TNF, and changes in the activities of JNK and PDTC were determined. The activity of the pump was assayed by measuring the ouabain-inhibitable release of inorganic phosphate. The effect of the cytokine was abrogated completely when JNK and caspases were inhibited but was unaffected by NF-kappaB inhibition. The role of each mediator in the signalling cascade was studied further by applying different combinations of the inhibitors. TNF-alpha was found to act at 1 h by activating caspases, which in turn activate JNK; the latter exerts an inhibitory effect on NF-kappaB, a transcription factor that stimulates the Na(+)/K(+) ATPase when active. It was concluded that TNF-alpha exerts opposite effects on the Na(+)/K(+)ATPase at different times, though the effects are always mediated via cJNK, NF-kappaB and caspases.

Topics: Amino Acid Chloromethyl Ketones; Animals; Anthracenes; Caspase Inhibitors; Caspases; Cysteine Proteinase Inhibitors; JNK Mitogen-Activated Protein Kinases; LLC-PK1 Cells; NF-kappa B; Pyrrolidines; Signal Transduction; Sodium-Potassium-Exchanging ATPase; Swine; Thiocarbamates; Tumor Necrosis Factor-alpha

Mitogen-activated protein kinases (MAPKs) are a family of Ser/Thr protein kinases that transmit various extracellular signals to the nucleus inducing gene expression, cell proliferation, and apoptosis. Recent studies have revealed that organotin compounds induce apoptosis and MAPK phosphorylation/activation in mammal cells. In this study, we elucidated the cytotoxic mechanism of tributyltin (TBT), a representative organotin compound, in rainbow trout (Oncorhynchus mykiss) RTG-2 cells. TBT treatment resulted in significant caspase activation, characteristic morphological changes, DNA fragmentation, and consequent apoptotic cell death in RTG-2 cells. TBT exposure induced the rapid and sustained accumulation of phosphorylated MAPKs, including extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 MAP kinase (p38 MAPK). Further analysis using pharmacological inhibitors against caspases and MAPKs showed that TBT also induced cell death in a caspase-independent manner and that p38 MAPK is involved in TBT-induced caspase-independent cell death, whereas JNK is involved in the caspase-dependent apoptotic pathway. Thus, TBT employs at least two independent signaling cascades to mediate cell death in RTG-2 cells. To our knowledge, this is the first study revealing the relationship between MAPK activation and TBT cytotoxicity in RTG-2 cells.

Topics: Amino Acid Chloromethyl Ketones; Animals; Anthracenes; Apoptosis; Caspase Inhibitors; Caspases; Cell Death; Cells, Cultured; Enzyme Activation; Imidazoles; JNK Mitogen-Activated Protein Kinases; MAP Kinase Signaling System; Oncorhynchus mykiss; p38 Mitogen-Activated Protein Kinases; Pyridines; Trialkyltin Compounds

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a cardiogenic and cardiohypertrophic growth factor. ProHB-EGF, a product of the Hb-egf gene and the precursor of HB-EGF, is anchored to the plasma membrane. Its ectodomain region is shed by a disintegrin and metalloproteases (ADAMs) when activated by various stimulations. It has been reported that an uncleavable mutant of Hb-egf, uc-Hb-egf, produces uc-proHB-EGF, which is not cleaved by ADAMs and causes dilation of the heart in knock-in mice. This suggests that the shedding of proHB-EGF is essential for the development and survival of cardiomyocytes: however, the molecular mechanism involved has remained unclear. In this study, we investigated the relationship between uc-proHB-EGF expression and cardiomyocyte survival. Human uc-proHB-EGF was adenovirally introduced into the rat cardiomyoblast cell line H9c2, and the cells were cultured under normoxic and hypoxic conditions. Uc-proHB-EGF-expressing H9c2 cells underwent apoptosis under normoxic conditions, which distinctly increased under hypoxic conditions. Furthermore, we observed an increased Caspase-3 activity, reactive oxygen species accumulation, and an increased c-Jun N-terminal kinase (JNK) activity in the uc-proHB-EGF-expressing H9c2 cells. Treatment of the uc-proHB-EGF transfectants with inhibitors of Caspase-3, reactive oxygen species, and JNK, namely, Z-VAD-fmk, N-acetylcysteine, and SP600125, respectively, significantly reduced hypoxic cell death. These data indicate that insufficiency of proHB-EGF shedding under hypoxic stress leads to cardiomyocyte apoptosis via Caspase-3- and JNK-dependent pathways.

Topics: Acetylcysteine; Amino Acid Chloromethyl Ketones; Animals; Anthracenes; Apoptosis; Caspase 3; Cell Hypoxia; Cell Line; Cell Membrane; Cysteine Proteinase Inhibitors; Disintegrins; Free Radical Scavengers; Heparin-binding EGF-like Growth Factor; Humans; Intercellular Signaling Peptides and Proteins; JNK Mitogen-Activated Protein Kinases; Mice; Mutation; Myoblasts, Cardiac; Rats; Reactive Oxygen Species

In species with hemochorial placentation, such as the mouse and human, trophoblast cells of the implanting blastocyst induce apoptosis and displace endometrial epithelial cells (EEC) to cross the luminal epithelium of the endometrium. Since Fas and Fas ligand (FasL) are expressed in EEC and trophoblast cells respectively and mitogen-activated protein kinases (MAPKs) mediate Fas-induced apoptosis, the roles of Fas/FasL and MAPK signaling in trophoblast-EEC interactions were studied. By co-culturing BeWo trophoblast spheroids with RL95-2 EEC monolayers to mimic blastocyst-endometrial interactions, we found that trophoblast spheroid outgrowth on EEC was significantly enhanced by anti-Fas activating antibody. Since anti-Fas activating antibody had no effect on spheroid expansion on EEC-free culture surfaces, its enhancing effect on spheroid outgrowth on EEC may be mediated by acting on EEC to facilitate trophoblast-induced EEC apoptosis and displacement. Valyl-alanyl-aspartyl-[O-methyl]-fluoromethylketone (VAD-FMK) staining showed that the percentage of apoptotic EEC at the spheroid-EEC interface was markedly increased by anti-Fas activating antibody. Moreover, the pancaspase inhibitor benzyloxycarbonyl-VAD-FMK was able to suppress the enhancing effect of anti-Fas activating antibody on spheroid expansion on EEC. Upon anti-Fas activating antibody stimulation, both p38 MAPK and c-Jun NH(2)-terminal kinase (JNK) were activated. Furthermore, the anti-Fas activating antibody-enhanced EEC apoptosis and spheroid expansion on EEC were significantly inhibited by the p38 MAPK inhibitor SB203580 and JNK inhibitor SP600125. Our results establish that anti-Fas activating antibody could activate p38 MAPK and JNK to induce EEC apoptosis, thereby promoting trophoblast outgrowth on EEC.

Topics: Amino Acid Chloromethyl Ketones; Anthracenes; Antibodies, Monoclonal; Apoptosis; Caspases; Cell Line, Tumor; Cell Proliferation; Coculture Techniques; Cysteine Proteinase Inhibitors; Embryo Implantation; Endometrium; Epithelial Cells; fas Receptor; Female; Humans; Imidazoles; JNK Mitogen-Activated Protein Kinases; Mitogen-Activated Protein Kinases; Models, Biological; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Protein Kinase Inhibitors; Pyridines; Trophoblasts

The mechanism of apoptosis induced by treatment with As(2)O(3) alone or in combination with buthionine sulfoximine (BSO) was studied in NB4, U937, Namalwa, and Jurkat cells. As(2)O(3) at concentrations <2 micromol/L induced apoptosis in NB4 cells and Namalwa cells but not in U937 and Jurkat cells. As(2)O(3)-induced apoptosis in NB4 cells and Namalwa cells correlated with increase of H(2)O(2) and caspase activation without activation of c-Jun NH(2)-terminal kinase (JNK). BSO (10 micromol/L) depleted the reduced form of intracellular glutathione without inducing apoptosis but synergized with 1 micromol/L As(2)O(3) to induce apoptosis in all four cell lines. This synergy correlated with JNK activation. Treatment with As(2)O(3) plus BSO, but not with As(2)O(3) alone, increased the levels of death receptor (DR) 5 protein and caspase-8 cleavage. The JNK inhibitor SP600125 inhibited the increase in DR5 protein and attenuated apoptosis induced by treatment with As(2)O(3) plus BSO. These observations suggest that a DR-mediated pathway activated by JNK is involved in apoptosis induced by treatment with As(2)O(3) plus BSO.

Topics: Amino Acid Chloromethyl Ketones; Anthracenes; Apoptosis; Arsenic Trioxide; Arsenicals; Blotting, Western; Buthionine Sulfoximine; Caspase 3; Caspase Inhibitors; Cell Proliferation; Dose-Response Relationship, Drug; Drug Synergism; Enzyme Activation; Glutathione; Humans; Hydrogen Peroxide; JNK Mitogen-Activated Protein Kinases; Jurkat Cells; Leukemia; Lymphoma; Oxides; Receptors, TNF-Related Apoptosis-Inducing Ligand; Time Factors; U937 Cells

Flavopiridol was developed as a drug for cancer therapy due to its ability to inhibit cell cycle progression by targeting cyclin-dependent kinases (CDKs). In this study, we show that flavopiridol may also have a neuroprotective action. We show that at therapeutic dosage (or at micromolar range), flavopiridol almost completely prevents colchicine-induced apoptosis in cerebellar granule neurones. In agreement with this, flavopiridol inhibits both the release of cyt c and the activation of caspase-3 induced in response to colchicine treatment. We demonstrate that in this cellular model for neurotoxicity, neither re-entry in the cell cycle nor activation of stress-activated protein kinases, such as c-Jun N-terminal kinase (JNK) or p38 MAP kinase, is involved. In contrast, we show that colchicine-induced apoptosis correlates with a substantial increase in the expression of cdk5 and Par-4, which is efficiently prevented by flavopiridol. Accordingly, a cdk5 inhibitor such as roscovitine, but not a cdk4 inhibitor such as 3-ATA, was also able to protect neurons from apoptosis as well as prevent accumulation of cdk5 and Par-4 in response to colchicine. Our data suggest a potential therapeutic use of flavopiridol in disorders of the central nervous system in which cytoskeleton alteration mediated by cdk5 activation and Par-4 expression has been demonstrated, such as Alzheimer's disease.

Topics: Amino Acid Chloromethyl Ketones; Animals; Animals, Newborn; Anthracenes; Anti-Bacterial Agents; Apoptosis; Apoptosis Regulatory Proteins; Blotting, Western; Bromodeoxyuridine; Carrier Proteins; Caspase 3; Caspases; CDC2-CDC28 Kinases; Cell Count; Cell Survival; Cells, Cultured; Cerebellum; Chromatin; Colchicine; Cyclin E; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase 5; Cyclin-Dependent Kinases; Cytochromes c; Dose-Response Relationship, Drug; Enzyme Inhibitors; Excitatory Amino Acid Agonists; Flavonoids; Flow Cytometry; Immunohistochemistry; Intracellular Signaling Peptides and Proteins; JNK Mitogen-Activated Protein Kinases; Kainic Acid; MAP Kinase Kinase 4; Microtubules; Minocycline; Mitogen-Activated Protein Kinase Kinases; Neurons; Neuroprotective Agents; Piperidines; Purines; Rats; Rats, Sprague-Dawley; Roscovitine; Time Factors; Tubulin