OBJECTIVETo determine whether 5-lipoxygenase (5-LOX) is involved in rotenone-induced injury in PC12 cells, which is a cell model of Parkinson disease.

METHODSAfter rotenone treatment for various durations, cell viability was determined by colorimetric MTT reduction assay, and 5-LOX translocation was detected by immunocytochemistry. The effect of 5-LOX inhibitor zileuton was also investigated.

RESULTRotenone (0.3-30 μmol/L) induced PC12 cell injury, and zileuton (3-100 μmol/L) attenuated this injury. Rotenone also time-and concentration-dependently induced 5-LOX translocation into the nuclear envelope, and zileuton (1-30 μmo/L) significantly inhibited rotenone-induced 5-LOX translocation.

CONCLUSION5-LOX is involved in rotenone-induced injury in PC12 cells, and 5-LOX inhibitor zileuton can reduce rotenone-induced 5-LOX activation and cell injury.

Animals ; Arachidonate 5-Lipoxygenase ; metabolism ; physiology ; Cell Survival ; drug effects ; Hydroxyurea ; analogs & derivatives ; pharmacology ; Lipoxygenase Inhibitors ; pharmacology ; PC12 Cells ; Rats ; Rotenone ; pharmacology

OBJECTIVETo examine the effect of a selective inhibitor of 5-lipoxygenase (5-LOX) zileuton on microglia-mediated rotenone neurotoxicity.

METHODSThe supernatant from different concentrations of rotenone-stimulated mouse microglia BV2 cells was used as the conditioned media (CM) for PC12 cells. The viability of PC12 cells was determined by MTT assay and lactate dehydrogenase (LDH) release. Cell death was observed by LDH release and double fluorescence staining with Hoechst/propidiumiodide (PI). The effect of zileuton on microglia-mediated rotenone toxicity was evaluated by the above methods.

RESULTSRotenone at 1-10 nmol/L was nontoxic to PC12 cells directly. However, the CM from BV2 cells that were treated with rotenone (1-10 nmol/L) resulted in toxicity of PC12 cells. The BV2 CM which stimulated with rotenone (1-10 nmol/L) induced morphological changes, reduced cell viability, and increased LDH release and cell necrosis in PC12 cells. Pretreatment of BV2 cells with the 5-LOX inhibitor zileuton (0.01-1 μmol/L) protected PC12 cells from the microglia-mediated rotenone toxicity.

CONCLUSIONThe 5-LOX inhibitor zileuton effectively attenuates microglia-mediated rotenone toxicity in PC12 cells. These results suggest that 5-LOX pathway may be involved in neuronal death induced by microglial inflammation.

Animals ; Cell Death ; drug effects ; Cells, Cultured ; Hydroxyurea ; analogs & derivatives ; pharmacology ; Lipoxygenase Inhibitors ; pharmacology ; Mice ; Microglia ; cytology ; PC12 Cells ; Rats ; Rotenone ; toxicity

Mesenchymal stem cells (MSC) are important cellular component of the bone marrow microenvironment in supporting hemopoiesis. Li J et al reported previously that MSCs are resistant to chemotherapy commonly used in hematologic malignancies but are relatively sensitive to anti-microtubule agents. However, the response of MSCs to other chemotherapeutic agents commonly used in solid tumour settings remains unknown. This study was purposed to evaluate the acute direct effects of 4 individual chemotherapeutic agents on human MSCs (hMSC), including cisplatin, topotecan, daunorubicin and hydroxyurea. Using an in vitro culture system, the chemosensitivity of hMSC was determined by XTT assay and compared with NB-4 cells and normal peripheral blood mononuclear cells (PBMNC). The recovery of cell numbers following exposure to chemotherapeutic agents and apoptosis induced by chemotherapy in hMSC were evaluated. The results showed that although hMSCs were more resistant to the 4 agents above mentioned than NB-4 cells, they were sensitive to topotecan, cisplatin and daunorubicin than PBMNCs. The IC₅₀ values of hMSCs for topotecan, cisplatin, hydroxyurea and daunorubicin were 636, 24.8, > 20 and 2.4 times of those of NB-4 cells respectively. The IC₅₀ values of human PBMNCs for topotecan, cisplatin and daunorubicin were > 27, 1.9 and 1.4 times of those of hMSCs respectively. Reduction of cell number was observed in hMSCs treated with the 4 drugs in clinically relative concentrations. Sustained suppression in hMSCs was observed following 3 days exposure to the 4 agents. It is concluded that the cisplatin, topotecan, daunorubicin and hydroxyurea alone can induce apoptosis of hMSCs and exert persistent suppressive effect on the proliferation of hMSCs even with short term exposure.
Antineoplastic Agents ; pharmacology ; Bone Marrow Cells ; cytology ; drug effects ; Cells, Cultured ; Cisplatin ; pharmacology ; Daunorubicin ; pharmacology ; Humans ; Hydroxyurea ; pharmacology ; Inhibitory Concentration 50 ; Mesenchymal Stromal Cells ; cytology ; drug effects ; Topotecan ; pharmacology

OBJECTIVETo investigate NK cell cytotoxicity to leukemic cell by NKG2D receptors and NKG2D ligands interaction upregulated by hydroxyurea (HU).

METHODSLeukemic cell lines OUN-1 and primary leukemic cells were cultured for 24 hours in the presence of HU, then the NKG2D ligands expressions were analyzed by flow cytometry (FCM). Isolated NK cells from healthy individual cultured for 72 hours in presence of IL-2 were used as effect cell, and leukemic cell line OUN-1 treated with HU was used as target cell, NK cell cytotoxicity against leukemic cell line was assessed using chromium-51 release assay.

RESULTSLeukemic cell lines showed upregulation of MIC A/B (MFI: 8.9 ± 0.9 vs 23.5 ± 3.4, P = 0.01) and ULBP2 (MFI: 14.5 ± 0.6 vs 33.5 ± 4.8, P = 0.03) following incubation with HU. HU also upregulated the NKG2DLs on primary leukemia cells from patients with acute myeloid leukemia. Treatment of OUN-1 with HU significantly increased the cytotoxicity of NK cells isolated from healthy individual \[(62.0 ± 5.6)% vs (76.0 ± 5.3)%, P = 0.02\], and the enhancing effect of HU was partly blocked by anti-NKG2D Abs \[(76.0 ± 5.3)% vs (46.0 ± 4.5)%, P = 0.00\].

CONCLUSIONHU selectively upregulated NKG2D ligand expression on leukemic cell lines, and enhanced NK cell cytotoxicity against leukemic cells through NKG2D receptors and NKG2D ligands interaction.

Cell Line, Tumor ; Humans ; Hydroxyurea ; pharmacology ; Killer Cells, Natural ; drug effects ; immunology ; Leukemia ; immunology ; Ligands ; NK Cell Lectin-Like Receptor Subfamily K ; immunology

The Rad1 gene is evolutionarily conserved from yeast to human. The fission yeast Schizosaccharomyces pombe Rad1 ortholog promotes cell survival against DNA damage and is required for G(2)/M checkpoint activation. In this study, mouse embryonic stem (ES) cells with a targeted deletion of Mrad1, the mouse ortholog of this gene, were created to evaluate its function in mammalian cells. Mrad1 (-/-) ES cells were highly sensitive to ultraviolet-light (UV light), hydroxyurea (HU) and gamma rays, and were defective in G(2)/M as well as S/M checkpoints. These data indicate that Mrad1 is required for repairing DNA lesions induced by UV-light, HU and gamma rays, and for mediating G(2)/M and S/M checkpoint controls. We further demonstrated that Mrad1 plays an important role in homologous recombination repair (HRR) in ES cells, but a minor HRR role in differentiated mouse cells.
Animals ; Cell Division ; Cell Proliferation ; DNA Damage ; DNA Repair ; Embryonic Stem Cells ; metabolism ; Exonucleases ; genetics ; metabolism ; physiology ; G2 Phase ; Gamma Rays ; Gene Deletion ; Hydroxyurea ; pharmacology ; Mice ; Ultraviolet Rays

OBJECTIVETo determine 5-lipoxygenase (5-LOX) expression and the effect of zileuton, a selective 5-LOX inhibitor,on hippocampal neuron injury induced by global cerebral ischemia in rats.

METHODSGlobal cerebral ischemia was induced by bilateral common carotid artery occlusion combined with hypotension in rats. 5-LOX expression was detected by Western blot analyses and 5-LOX localization was visualized by immunohistochemistry and double immunofluorescence methods. The 5-LOX inhibitor zileuton (10, 30, 50 mg/kg) was orally administered for 3 d after ischemia.

RESULTSThe 5-LOX expression was increased in the ischemic hippocampus on d1-7 (peaked at d3), and 5-LOX protein was primarily localized in neurons and translocated to the nuclei in the hippocampal CA1 region after ischemia. The 5-LOX inhibitor zileuton (30, 50 mg/kg) reduced ischemia-induced hippocampal neurons death 3d after ischemia.

CONCLUSION5-LOX is involved in global cerebral ischemic damage in rats, and the 5-LOX inhibitor zileuton has a protective effect on neuronal damage in the rat hippocampus following global cerebral ischemia.

Animals ; Arachidonate 5-Lipoxygenase ; metabolism ; physiology ; Brain Ischemia ; metabolism ; pathology ; CA1 Region, Hippocampal ; metabolism ; pathology ; Disease Models, Animal ; Hydroxyurea ; analogs & derivatives ; pharmacology ; Lipoxygenase Inhibitors ; pharmacology ; Male ; Neurons ; drug effects ; pathology ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo explore the molecular mechanism via which the chemotherapeutic drug hydroxyurea (HU) enhances K562 cell apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL).

METHODSChronic myelogenous leukemia-derived K562 and SVT-35 cells were treated with recombinant soluble TRAIL (rsTRAIL) alone or combined with HU for a time course, and the cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-4-sulfophenyl-2H-tetrazolium-phenazine methosulphate assay. Western blot was performed to analyze the activation of apoptosis-related protein kinases and the expression of apoptosis inhibitor molecules.

RESULTSThe survival rates of SVT-35 and K562 cells treated with 1 μg/ml rsTRAIL for 24 hours were 32% and 93%, respectively. HU significantly increased the sensitivity of K562 cells to rsTRAIL cytotoxicity. Combination of rsTRAIL and HU resulted in the phosphorylation of rat sarcoma (RAS), mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK), extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase and in the significant reduction of apoptosis-inhibited molecule Fas associated death domain protein-like interleukin-1 beta-convening enzyme inhibitory protein and cellular inhibitor of apoptosis protein-1 in K562 cells.

CONCLUSIONSHU enhanced K562 cell sensitivity to rsTRAIL is mediated by Ras-MEK-ERK signaling pathway. Expression of antiapoptotic proteins cellular Fas associated death domain protein-like interleukin-1 beta-convening enzyme inhibitory protein and cellular inhibitor of apoptosis protein-1 is also down-regulated during this process. These results may through light on the therapeutic study of human chronic myelogenous leukemia.

Apoptosis ; drug effects ; physiology ; CASP8 and FADD-Like Apoptosis Regulating Protein ; metabolism ; Humans ; Hydroxyurea ; pharmacology ; Inhibitor of Apoptosis Proteins ; metabolism ; K562 Cells ; MAP Kinase Signaling System ; TNF-Related Apoptosis-Inducing Ligand ; pharmacology

OBJECTIVETo investigate the effects of combined use of low-dose hydroxyurea (HU) and sodium butyrate (NaB) on the expression of 7 globin genes (zeta, alpha, epsilon, Ggamma, Agamma, delta, and beta) in human erythroid progenitor cells.

METHODSHuman erythroid progenitor cells were cultured using a two-step liquid culture system and treated with HU and NaB either alone or in combination. The inhibitory effects of the agents on the cell growth were monitored with trypan blue exclusion assay, and the changes in the mRNA of the 7 globin genes were detected using RT-PCR.

RESULTSLow-dose HU combined with NaB resulted in significantly lower inhibition rate of the erythroid progenitor cells than routine dose HU and NaB used alone (28.56% and 38.80%, respectively, P<0.05). Compared with untreated cells (0.653-/+0.092 and 0.515-/+0.048), HU combined with NaB significantly increased the expression of Ggamma-and Agamma- mRNA (1.203-/+0.018 and 0.915-/+0.088, respectively, P<0.05), and HU and NaB used alone produced similar effects (1.305-/+0.016 and 0.956-/+0.029 for HU, and 1.193-/+0.070 and 0.883-/+0.012 for NaB, P>0.05). HU and NaB, either used alone or in combination or at different doses, caused no significant changes in the other globin genes (zeta, alpha, epsilon, delta and beta) (P>0.05).

CONCLUSIONLow-dose HU combined with NaB can up-regulate gamma globin gene expression, especially Ggamma-mRNA expression, to decrease the growth inhibition on human erythroid progenitor cells in vitro, but produces no significant effect on the expressions of zeta, alpha, epsilon, delta and beta genes.

Anemia, Sickle Cell ; genetics ; Butyrates ; administration & dosage ; pharmacology ; therapeutic use ; Cells, Cultured ; Drug Therapy, Combination ; Erythroid Precursor Cells ; cytology ; drug effects ; physiology ; Erythropoiesis ; drug effects ; Humans ; Hydroxyurea ; administration & dosage ; pharmacology ; therapeutic use ; RNA, Messenger ; genetics ; metabolism ; gamma-Globins ; genetics ; metabolism

OBJECTIVETo investigate the tumor-suppression effect of hydroxyurea on meningioma cells and its possible mechanism.

METHODSThe meningioma cells were cultured in medium containing varied doses of hydroxyurea (5x10(-3)mol/L, 5x10(-4)mol/L, 5x10(-5)mol/L), the cell growth was measured by MTT method, cell apoptosis was observed with flow cytometry (FCM).

RESULTSMTT measurement demonstrated that the administration of hydroxyurea led to a dose-dependent suppression in cell proliferation and FCM showed a dose-dependent increase in apoptosis rate.

CONCLUSIONHydroxyurea can inhibit meningioma cell growth in vitro, which is most likely associated with apoptosis of the tumor cells.

Adult ; Aged ; Apoptosis ; drug effects ; Cell Division ; drug effects ; Cell Line, Tumor ; Dose-Response Relationship, Drug ; Female ; Flow Cytometry ; Humans ; Hydroxyurea ; pharmacology ; Male ; Meningioma ; drug therapy ; pathology ; Middle Aged

Hydroxyurea is commonly used to treat hematologic disorders and some type of solid tumors, but the mechanism for its therapeutic effect is not clearly known. In this study, we examined the effect of hydroxyurea on rat hepatoma McA-RH7777 cells, specifically, on the role of mitogen-activated protein (MAP) kinase signal transduction pathways and p21Waf1, p27Kip1 and p53. Rat hepatoma McA-RH7777 cells treated with hydroxyurea for 7 days, caused the inhibition of cell growth in a dose-dependent manner. But, this growth inhibition was not caused by necrosis or apoptosis but instead was associated with cell senescence-like change as evidenced by senescence associated-beta-galactosidase staining, and cells arrest at G1 phase of cell cycle. Phosphorylation of MAP kinases, such as ERK, JNK, and p38, was found to be decreased after treatment of cells with hydroxyurea. But, the expression of p21Waf1 was increased, while p27Kip1 and p53 were not detected in hydroxyurea treated rat hepatoma cells. Hydroxyurea treatment induced G1 arrest and a senescence-like changes in rat hepatoma McA-RH7777 cells may be the likely results of signal disruption of MAP kinases (ERK, JNK, and p38 MAP kinase) and p21Waf1 over-expression.
Animals ; Antineoplastic Agents/*pharmacology ; Cell Aging/drug effects ; Cell Cycle Proteins/analysis/metabolism/*physiology ; Cell Line, Tumor ; Cell Proliferation/drug effects ; G1 Phase/drug effects/physiology ; Hydroxyurea/*pharmacology ; Liver Neoplasms, Experimental/enzymology/*metabolism ; Mitogen-Activated Protein Kinases/analysis/*physiology ; Phosphorylation/drug effects ; Protein p53/analysis/metabolism ; Rats ; Research Support, Non-U.S. Gov't ; Tumor Suppressor Proteins/analysis/metabolism ; Up-Regulation