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1.
RSC Adv ; 14(15): 10653-10661, 2024 Mar 26.
Article in English | MEDLINE | ID: mdl-38567327

ABSTRACT

Self-reporting systems automatically indicate damaged or corroded surfaces via color changes or fluorescence. In this study, a novel reusable self-reporting system is developed by exploiting the reversibility of a donor-acceptor Stenhouse adduct (DASA). The synthesized DASA precursor exhibits a color change when damaged upon reaction with diethylamine, and returns to its colorless form upon irradiation with visible light. Microcapsules are synthesized with a core comprising styrene and the DASA precursor, along with a shell formed of urea and formaldehyde. The optimal particle size and shell thickness of the microcapsules are 225 µm and 0.17 µm, respectively. The DASA precursor-containing microcapsules are embedded in a PEG gel matrix with secondary amine groups. This coating system, initially colorless, exhibits a color change, becoming pink after being damaged by scratching due to the reaction between the DASA precursor released from ruptured microcapsules with the secondary amine groups of the PEG gel, thus demonstrating self-reporting characteristics. Furthermore, the colored surface is restored to its initial colorless state by irradiation with visible light for 1.5 hours, demonstrating the reusability of the self-reporting system.

2.
Sensors (Basel) ; 23(23)2023 Nov 24.
Article in English | MEDLINE | ID: mdl-38067755

ABSTRACT

This paper describes a signal quality classification method for arm ballistocardiogram (BCG), which has the potential for non-invasive and continuous blood pressure measurement. An advantage of the BCG signal for wearable devices is that it can easily be measured using accelerometers. However, the BCG signal is also susceptible to noise caused by motion artifacts. This distortion leads to errors in blood pressure estimation, thereby lowering the performance of blood pressure measurement based on BCG. In this study, to prevent such performance degradation, a binary classification model was created to distinguish between high-quality versus low-quality BCG signals. To estimate the most accurate model, four time-series imaging methods (recurrence plot, the Gramain angular summation field, the Gramain angular difference field, and the Markov transition field) were studied to convert the temporal BCG signal associated with each heartbeat into a 448 × 448 pixel image, and the image was classified using CNN models such as ResNet, SqueezeNet, DenseNet, and LeNet. A total of 9626 BCG beats were used for training, validation, and testing. The experimental results showed that the ResNet and SqueezeNet models with the Gramain angular difference field method achieved a binary classification accuracy of up to 87.5%.


Subject(s)
Algorithms , Ballistocardiography , Ballistocardiography/methods , Heart Rate/physiology , Artifacts , Motion
3.
RSC Adv ; 13(34): 24071-24076, 2023 Aug 04.
Article in English | MEDLINE | ID: mdl-37577101

ABSTRACT

We have successfully synthesized a novel form of polyglycerol with an unprecedentedly low degree of branching (DB = 0.08-0.18), eliminating the need for glycidol protection. Leveraging the remarkable efficiency and selectivity of our Cu(triNHC) catalyst, comprising copper(i) ions and NHC ligands, we achieved a highly selective polymerization process. The proposed Cu-coordination mechanisms presented the formation of linear L1,3 units while effectively suppressing dendritic units. Consequently, our pioneering approach yielded polyglycerol with an ultralow DB and exceptional yields. To comprehensively assess the physical properties and topology of the synthesized polyglycerol, we employed 1H diffusion-ordered spectroscopy, size-exclusion chromatography, and matrix-assisted laser desorption/ionization-time of flight spectrometry. Remarkably, the ultralow-branched cyclic polyglycerol (DB = 0.08) synthesized at 0 °C showcased extraordinary characteristics, exhibiting the lowest diffusion coefficient and the highest molecular weight. This achievement establishes the significant potential of our polyglycerol with a low degree of branching, revolutionizing the field of biocompatible polymers.

4.
Front Plant Sci ; 14: 1158288, 2023.
Article in English | MEDLINE | ID: mdl-37152153

ABSTRACT

The shade avoidance syndrome (SAS) is a collective adaptive response of plants under shade highlighted by characteristic phenotypes such as hypocotyl elongation, which is largely mediated by concerted actions of auxin and GA. We identified ATHB2, a homeodomain-leucine zipper (HD-Zip) domain transcription factor known to be rapidly induced under shade condition, as a positive regulator of GA biosynthesis necessary for the SAS by transactivating the expression of GA20ox2, a key gene in the GA biosynthesis pathway. Based on promoter deletion analysis, EMSA and ChIP assay, ATHB2 appears to regulate the GA20ox2 expression as a direct binding target. We also found that the GA20ox2 expression is under negative control by TCP13, the effect of which can be suppressed by presence of ATHB2. Considering a rapid induction kinetics of ATHB2, this relationship between ATHB2 and TCP13 may allow ATHB2 to play a shade-specific activator for GA20ox by derepressing a pre-existing activity of TCP13.

5.
Glob Health Action ; 11(1): 1523303, 2018.
Article in English | MEDLINE | ID: mdl-30270794

ABSTRACT

BACKGROUND: Despite remarkable progress in water coverage improvements, diseases associated with poor water remain a considerable public health problem in many developing countries. OBJECTIVE: We aimed to estimate the costs and benefits of drilling or rehabilitating boreholes with handpumps in resource-poor settings and hard-to-reach areas. METHODS: Diarrheal reduction in the population was predicted on the basis of the empirical findings from a cluster randomized controlled trial. The full investment and estimated annual running costs were used to calculate the intervention costs. Direct economic benefits of avoiding child diarrheal disease, indirect economic benefits related to health improvements, and non-health benefits related to water improvement were estimated. One-way and multi-way sensitivity analyses were performed to determine the robustness of the findings. RESULTS: Our analysis found that the return on a US$ 1 investment was US$ 9.4 for borehole drilling and US$ 14.1 for borehole rehabilitation. Time savings were the main contributor, accounting for 68% of the benefits, followed by the economic benefits of averted child deaths, which contributed to 15% of the benefits. The sensitivity analyses suggested that improving water sources yields high returns under all circumstances, and that borehole rehabilitation is more efficient than borehole drilling. CONCLUSION: This study explicitly justifies increased investment in water improvement in rural areas and demonstrates the high returns of rehabilitating boreholes. We hope that this study will be used as evidence for informing the policy decisions of governments or international agencies regarding further investments in improved water coverage in rural areas and the selection of appropriately designed interventions.


Subject(s)
Cost-Benefit Analysis/statistics & numerical data , Developing Countries/statistics & numerical data , Diarrhea/economics , Diarrhea/prevention & control , Public Health/economics , Water Supply/economics , Water Supply/statistics & numerical data , Female , Ghana , Humans , Male , Randomized Controlled Trials as Topic
6.
Dev Reprod ; 22(2): 133-142, 2018 Jun.
Article in English | MEDLINE | ID: mdl-30023463

ABSTRACT

Patients with type II diabetes mellitus are more susceptible to colorectal cancer (CRC) incidence than non-diabetics. The anti-diabetic drug metformin is most commonly prescribed for the treatment of this disease and has recently shown antitumor effect in preclinical studies. The aberrant mutational activation in the components of RAS/RAF/MEK/ERK and PI3K/AKT/mTOR signaling pathway is very frequently observed in CRC. We previously reported that metformin inhibits the phosphorylation of ERK and BEZ235, a dual inhibitor of PI3K and mTOR, has anti-tumor activity against HCT15 CRC cells harboring mutations of KRAS and PIK3CA. Therefore, we hypothesized that simultaneous inhibition of two pathways by combining metformin with BEZ235 could be more effective in the suppression of proliferation than single agent treatment in HCT15 CRC cells. Here, we investigated the combinatory effect of metformin and BEZ235 on the cell survival in HCT15 CRC cells. Our study shows that both of the two signaling pathways can be blocked by this combinational strategy: metformin suppressed both pathways by inhibiting the phosphorylation of ERK, 4E-BP1 and S6, and BEZ235 suppressed PI3K/AKT/ mTOR pathway by reducing the phosphorylation of 4E-BP1 and S6. This combination treatment synergistically reduced cell viability. The combination index (CI) values ranged from 0.44 to 0.88, indicating synergism for the combination. These results offer a preclinical rationale for the potential therapeutic option for the treatment of CRC.

7.
Mol Cells ; 33(5): 487-96, 2012 May.
Article in English | MEDLINE | ID: mdl-22526395

ABSTRACT

The role of Arabidopsis S6 Kinase 1 (AtS6K1), a downstream target of TOR kinase, in controlling plant growth and ribosome biogenesis was characterized after generating transgenic plants expressing AtS6K1 under auxin-inducible promoter. Down regulation of selected cell cycle regulatory genes upon auxin treatment was observed in the transgenic plants, confirming the negative regulatory role of AtS6K1 in the plant cell cycle progression reported earlier. Callus tissues established from these transgenic plants grew to larger cell masses with more number of enlarged cells than untransformed control, demonstrating functional implication of AtS6K1 in the control of plant cell size. The observed negative correlation between the expression of AtS6K1 and the cell cycle regulatory genes, however, was completely reversed in protoplasts generated from the transgenic plants expressing AtS6K1, suggesting a possible existence of dual regulatory mechanism of the plant cell cycle regulation mediated by AtS6K1. An alternative method of kinase assay, termed "substrate-mediated kinase pull down", was employed to examine the additional phosphorylation on other domains of AtS6K1 and verified the phosphorylation of both amino- and carboxy-terminal domains, which is a novel finding regarding the phosphorylation target sites on plant S6Ks by upstream regulatory kinases. In addition, this kinase assay under the stress conditions revealed the salt- and sugar-dependencies of AtS6K1 phosphorylations.


Subject(s)
Arabidopsis/metabolism , Cell Cycle/genetics , Plant Cells/metabolism , Plant Development/physiology , Plant Proteins/metabolism , Ribosomal Protein S6 Kinases/metabolism , Arabidopsis/drug effects , Arabidopsis/genetics , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Cell Cycle/drug effects , Cell Enlargement/drug effects , Cell Size/drug effects , DNA, Ribosomal/genetics , Gene Expression Regulation, Plant/drug effects , Indoleacetic Acids/pharmacology , Phosphorylation , Plant Cells/drug effects , Plant Cells/enzymology , Plant Growth Regulators/pharmacology , Plant Proteins/genetics , Plants, Genetically Modified , Promoter Regions, Genetic , Protoplasts/drug effects , Protoplasts/metabolism , Ribosomal Protein S6 Kinases/genetics , Ribosomes/drug effects , Ribosomes/genetics , Ribosomes/metabolism , Transcription, Genetic/drug effects
8.
Fertil Steril ; 96(1): 187-92, 2011 Jul.
Article in English | MEDLINE | ID: mdl-21550043

ABSTRACT

OBJECTIVE: To explore the association between embryo fragmentation and necrosis and apoptosis. DESIGN: A prospective study. SETTING: Mizmedi Hospital. PATIENT(S): None. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Staining with annexin V (a marker of apoptosis) and propidium iodide (PI, a marker of necrosis), DNA integrity and mitochondrial distribution, and a beneficial effect of fragment removal in human fragmented embryos. RESULT(S): Most of the mouse and human fragmented embryos were stained with PI but not with annexin V. The comet assay revealed severe DNA fragmentation of the fragmented human embryos but not of the unfragmented embryos. Fewer mitochondria were observed in the fragmented compared with the normal blastomeres, indicating a rapid depletion of ATP in the fragmented embryos. Microsurgical fragment removal from the embryos had a beneficial effect on their subsequent development. CONCLUSION(S): Fragments of human embryos exhibited various characteristics of necrosis, such as staining with PI, DNA fragmentation, rapid depletion of ATP, and harmful effects on neighboring blastomeres. We suggest that the fragmentation of embryos is closely associated with both necrosis and apoptosis. Whether this fragmentation is associated with primary or secondary necrosis remains to be elucidated.


Subject(s)
Apoptosis , DNA Fragmentation , Embryo, Mammalian/cytology , Embryo, Mammalian/pathology , Adult , Animals , Apoptosis/physiology , Embryo Transfer/methods , Embryo, Mammalian/physiology , Female , Humans , Mice , Necrosis , Prospective Studies , Young Adult
9.
Clin Exp Reprod Med ; 38(1): 10-7, 2011 Mar.
Article in English | MEDLINE | ID: mdl-22384412

ABSTRACT

OBJECTIVE: To explore potential relationships between sperm DNA integrity and both semen parameters and clinical outcomes. METHODS: Semen analysis of 498 samples was performed according to the 2010 criteria of the World Health Organization. The sperm DNA fragmentation Index (DFI) of the semen samples was assessed using a neutral comet assay. RESULTS: Sperm DFI showed a significant correlation with semen parameters, including the patient's age, sperm viability, motility, morphology, and number of leukocytes (p<0.05). The sperm DFI values for asthenozoospermic (15.2%), oligoteratozoospermic (18.3%), asthenoteratozoospermic (17.5%), and oligoasthenoteratozoospermic semen samples (21.3%) were significantly higher than that observed in normozoospermic semen samples (10.5%, p<0.05). A sperm DFI value of 14% was used as a threshold of sperm DFI in assessing whether DNA was highly damaged. In 114 IVF-ET cycles, the fertilization rate of the sperm DFI <14% group (70 cycles, 61.7%) was significantly higher than that observed for the ≥14% group (44 cycles, 55.3%), but there was no difference in the other clinical outcomes between the two groups. In the ≥14% group, the pregnancy rates of the ICSI cycles (40.0%) and half-ICSI (44.0%) were higher than conventional IVF cycles (30.7%), but the difference was not statistically significant. CONCLUSION: Along with the conventional semen analysis, the sperm DFI assessed using the comet assay was shown to improve the quality of the semen evaluation. To evaluate the precise effect of ICSI on pregnancy rates in the patients who demonstrate high sperm DFI values, further study is necessary.

10.
Mol Cancer Res ; 6(11): 1718-31, 2008 Nov.
Article in English | MEDLINE | ID: mdl-19010820

ABSTRACT

Exposure of cells to ionizing radiation induces activation of multiple signaling pathways that play critical roles in determining cell fate. However, the molecular basis for cell death or survival signaling in response to radiation is unclear at present. Here, we show opposing roles of the c-jun NH(2)-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) pathways in the mitochondrial cell death in response to ionizing radiation in human cervical cancer cells. Ionizing radiation triggered Bax and Bak activation, Bcl-2 down-regulation, and subsequent mitochondrial cell death. Inhibition of JNK completely suppressed radiation-induced Bax and Bak activation and Bcl-2 down-regulation. Dominant-negative forms of stress-activated protein kinase/extracellular signal-regulated kinase kinase 1 (SEK-1)/mitogen-activated protein kinase kinase-4 (MKK-4) inhibited JNK activation. Radiation also induced phosphoinositide 3-kinase (PI3K) activation. Interestingly, inhibition of PI3K effectively attenuated radiation-induced mitochondrial cell death and increased clonogenic survival. Inhibition of PI3K also suppressed SEK-1/MKK-4 and JNK activation, Bax and Bak activation, and Bcl-2 down-regulation. In contrast, inhibition of p38 MAPK led to enhanced Bax and Bak activation and mitochondrial cell death. RacN17, a dominant-negative form of Rac1, inhibited p38 MAPK activation and increased Bax and Bak activation. Exposure of cells to radiation also induced selective activation of c-Src among Src family kinases. Inhibition of c-Src by pretreatment with Src family kinase inhibitor PP2 or small interfering RNA targeting of c-Src attenuated radiation-induced p38 MAPK and Rac1 activation and enhanced Bax and Bak activation and cell death. Our results support the notion that the PI3K-SEK-1/MKK-4-JNK pathway is required for the mitochondrial cell death in response to radiation, whereas the c-Src-Rac1-p38 MAPK pathway plays a cytoprotective role against mitochondrial cell death.


Subject(s)
Apoptosis/radiation effects , Gamma Rays , JNK Mitogen-Activated Protein Kinases/metabolism , Uterine Cervical Neoplasms/metabolism , Uterine Cervical Neoplasms/pathology , p38 Mitogen-Activated Protein Kinases/metabolism , Cell Line, Tumor , Female , Genes, bcl-2 , Genes, src , Humans , MAP Kinase Kinase 4/metabolism , MAP Kinase Signaling System , Mitochondria/metabolism , Phosphatidylinositol 3-Kinases/metabolism , bcl-2 Homologous Antagonist-Killer Protein/metabolism , bcl-2-Associated X Protein/metabolism , rac1 GTP-Binding Protein/metabolism
11.
J Biochem Mol Biol ; 40(5): 656-61, 2007 Sep 30.
Article in English | MEDLINE | ID: mdl-17927897

ABSTRACT

In this report, we describe an optimized method for generation of ephA8 BAC transgenic mice expressing the lacZ reporter gene under ephA8 regulatory sequences. First, we constructed a targeting vector that carries a 1.2 kb ephA8 DNA upstream of its first exon, a lacZ expression cassette, a kanamycin cassette, and a 0.7 kb ephA8 DNA downstream of its first exon. Second, the targeting vector was electroporated into cells containing the ephA8 BAC and pKOBEGA, in which recombinases induce a homologous recombination between the ephA8 BAC DNA and the targeting vector. Third, the FLP plasmid expressing the Flipase was electroporated into these bacteria to eliminate a kanamycin cassette from the recombinant BAC DNA. The appropriate structures of the modified ephA8 BAC DNA were confirmed by Southern analysis. Finally, BAC transgenic mouse embryos were generated by pronuclear injection of the recombinant BAC DNA. Whole mount X-gal staining revealed that the lacZ reporter expression is restricted to the anterior region of the developing midbrain in each transgenic embryo. These results indicate that the ephA8 BAC DNA contains most, if not all, regulatory sequences to direct temporal and spatial expression of the lacZ gene in vivo.


Subject(s)
Chromosomes, Artificial, Bacterial/genetics , Lac Operon/genetics , Receptor, EphA8/genetics , Recombination, Genetic/genetics , Animals , Blotting, Southern , Embryo, Mammalian/metabolism , Female , Genetic Engineering/methods , Genetic Vectors/genetics , Mice , Mice, Inbred C57BL , Mice, Transgenic , Models, Genetic , Pregnancy
12.
Plant Cell Rep ; 26(8): 1179-85, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17387478

ABSTRACT

Homeobox genes are essential regulators of plant development. ATHB23, a class I homeodomain leucine zipper gene of Arabidopsis, was found to be induced by treatment with the phytohormone gibberellin (GA). In order to clarify its role in development, we performed a histochemical analysis of transgenic plants containing a construct with a GUS::GFP reporter under the control of the 1.5 kb upstream region of ATHB23. The construct was mainly expressed in young leaves and the styles of flowers but not in mature leaves. Microscopic examination of young leaves revealed that it was expressed in the adaxial domain of leaf primordia and the rib meristem. Expression of ATHB23, like that of GA5 encoding GA 20-oxidase, was reduced in mutants related to adaxial-abaxial leaf polarity (phb-1d, se-2, and kan1 kan2). Reduced expression of the GUS::GFP reporter gene was also observed in an se-2 background. These results indicate that ATHB23 is under the control of GA and other activators such as PHB, and is involved in establishing polarity during leaf development.


Subject(s)
Arabidopsis Proteins/biosynthesis , Arabidopsis/genetics , Homeodomain Proteins/genetics , Leucine Zippers/genetics , Plant Leaves/metabolism , Arabidopsis/metabolism , Arabidopsis Proteins/genetics , Gene Expression Regulation, Plant/drug effects , Gibberellins/pharmacology , Homeodomain Proteins/biosynthesis , Meristem/metabolism , Mutation
13.
Oncol Rep ; 17(1): 175-84, 2007 Jan.
Article in English | MEDLINE | ID: mdl-17143496

ABSTRACT

Sensitization of cancer cells to TRAIL could improve the effectiveness of TRAIL as an anticancer agent. We explored whether TRAIL in combination with phytosphingosine could sensitize cancer cells to TRAIL. The combined treatment enhanced synergistic apoptotic cell death of Jurkat T cells, compared to TRAIL or phytosphingosine alone. Enhanced apoptosis in response to the combination treatment was associated with caspase-8 activation-mediated Bax and Bak activation and mitochondrial dysfunction. The combination treatment also resulted in synergistic up-regulation of TRAIL receptor R1 (DR4) and R2 (DR5). siRNA targeting of DR5 significantly attenuated the combination treatment-induced caspase-8 activation, mitochondrial dysfunction, and apoptotic cell death. Upon stimulation of cells with the combination treatment, NF-kappaB was activated. Moreover, siRNA targeting of NF-kappaB significantly attenuated the combination treatment-induced DR4 and DR5 expression and receptor-mediated caspase-8 activation. These results indicate that phytosphingosine sensitizes cancer cells to TRAIL through the synergistic up-regulation of DR4 and DR5 in an NF-kappaB-dependent fashion resulting in caspase-8 activation and subsequent mitochondrial dysfunction. These findings support the potential application of combination treatment with TRAIL and phytosphingosine in the treatment of cancers that are less sensitive to TRAIL.


Subject(s)
Antineoplastic Combined Chemotherapy Protocols/pharmacology , Lymphoma, T-Cell/drug therapy , Receptors, TNF-Related Apoptosis-Inducing Ligand/biosynthesis , Receptors, Tumor Necrosis Factor/biosynthesis , Sphingosine/analogs & derivatives , TNF-Related Apoptosis-Inducing Ligand/pharmacology , Apoptosis/drug effects , Apoptosis/physiology , BH3 Interacting Domain Death Agonist Protein/metabolism , Carcinoma, Non-Small-Cell Lung/drug therapy , Carcinoma, Non-Small-Cell Lung/metabolism , Carcinoma, Non-Small-Cell Lung/pathology , Caspase 8/metabolism , Drug Synergism , Enzyme Activation/drug effects , Humans , Jurkat Cells , Lung Neoplasms/drug therapy , Lung Neoplasms/metabolism , Lung Neoplasms/pathology , Lymphoma, T-Cell/metabolism , Lymphoma, T-Cell/pathology , Mitochondria/drug effects , Mitochondria/physiology , NF-kappa B/metabolism , Receptors, TNF-Related Apoptosis-Inducing Ligand/metabolism , Receptors, Tumor Necrosis Factor/metabolism , Recombinant Proteins/administration & dosage , Recombinant Proteins/pharmacology , Sphingosine/administration & dosage , Sphingosine/pharmacology , T-Lymphocytes/drug effects , TNF-Related Apoptosis-Inducing Ligand/administration & dosage , Up-Regulation/drug effects , bcl-2 Homologous Antagonist-Killer Protein/metabolism , bcl-2-Associated X Protein/metabolism
14.
J Biol Chem ; 281(11): 7049-59, 2006 Mar 17.
Article in English | MEDLINE | ID: mdl-16410245

ABSTRACT

Intracellular signaling molecules and apoptotic factors seem to play an important role in determining the radiation response of tumor cells. However, the basis for the link between signaling pathway and apoptotic cell death machinery after ionizing irradiation remains still largely unclear. In this study, we showed that c-Abl-PKCdelta-Rac1-p38 MAPK signaling is required for the conformational changes of Bak and Bax during ionizing radiation-induced apoptotic cell death in human non-small cell lung cancer cells. Ionizing radiation induced conformational changes and subsequent oligomerizations of Bak and Bax, dissipation of mitochondrial membrane potential, and cytochrome c release from mitochondria. Small interference (siRNA) targeting of Bak and Bax effectively protected cells from radiation-induced mitochondrial membrane potential loss and apoptotic cell death. p38 MAPK was found to be selectively activated in response to radiation treatment. Inhibition of p38 MAPK completely suppressed radiation-induced Bak and Bax activations, dissipation of mitochondrial membrane potential, and cell death. Moreover, expression of a dominant negative form of protein kinase Cdelta (PKCdelta) or siRNA targeting of PKCdelta attenuated p38 MAPK activation and conformational changes of Bak and Bax. In addition, ectopic expression of RacN17, a dominant negative form of Rac1, markedly inhibited p38 MAPK activation but did not affect PKCdelta activation. Upon stimulation of cells with radiation, PKCdelta was phosphorylated dramatically on tyrosine. c-Abl-PKCdelta complex formation was also increased in response to radiation. Moreover, siRNA targeting of c-Abl attenuated radiation-induced PKCdelta and p38 MAPK activations, and Bak and Bax modulations. These data support a notion that activation of the c-Abl-PKCdelta-Rac1-p38 MAPK pathway in response to ionizing radiation signals conformational changes of Bak and Bax, resulting in mitochondrial activation-mediated apoptotic cell death in human non-small cell lung cancer cells.


Subject(s)
Carcinoma, Non-Small-Cell Lung/metabolism , Lung Neoplasms/metabolism , Protein Kinase C/metabolism , Proto-Oncogene Proteins c-abl/metabolism , bcl-2 Homologous Antagonist-Killer Protein/metabolism , bcl-2-Associated X Protein/metabolism , p38 Mitogen-Activated Protein Kinases/metabolism , Apoptosis , Blotting, Western , Cell Death , Cell Line , Cell Line, Tumor , Cell Separation , Cross-Linking Reagents/pharmacology , Cytosol/metabolism , Enzyme Activation , Flow Cytometry , Humans , Immunoprecipitation , MAP Kinase Signaling System , Membrane Potentials , Mitochondria/metabolism , Phosphorylation , Protein Conformation , RNA, Small Interfering/metabolism , Radiation, Ionizing , Signal Transduction , Time Factors , Transfection , Tyrosine/chemistry
15.
Blood ; 105(4): 1724-33, 2005 Feb 15.
Article in English | MEDLINE | ID: mdl-15486061

ABSTRACT

The use of chemical modifiers as radiosensitizers in combination with low-dose irradiation may increase the therapeutic effect on cancer by overcoming a high apoptotic threshold. Here, we showed that phytosphingosine treatment in combination with gamma-radiation enhanced apoptotic cell death of radiation-resistant human T-cell lymphoma in a caspase-independent manner. Combination treatment induced an increase in intracellular reactive oxygen species (ROS) level, mitochondrial relocalization of B-cell lymphoma-2(Bcl-2)-associated X protein (Bax), poly-adenosine diphosphate (ADP)-ribose polymerase 1 (PARP-1) activation, and nuclear translocation of apoptosis-inducing factor (AIF). siRNA targeting of AIF effectively protected cells from the combination treatment-induced cell death. An antioxidant, N-acetyl-L-cysteine (NAC), inhibited Bax relocalization and AIF translocation but not PARP-1 activation. Moreover, transfection of Bax-siRNA significantly inhibited AIF translocation. Pretreatment of PARP-1 inhibitor, DPQ (3,4-dihydro-5-[4-(1-piperidinyl)-butoxy]-1(2H)-isoquinolinone), or PARP-1-siRNA also partially attenuated AIF translocation, whereas the same treatment did not affect intracellular ROS level and Bax redistribution. Taken together, these results demonstrate that enhancement of cell death of radiation-resistant cancer cells by phytosphingosine treatment in combination with gamma-radiation is mediated by nuclear translocation of AIF, which is in turn mediated both by ROS-dependent Bax relocalization and ROS-independent PARP-1 activation. The molecular signaling pathways that we elucidated in this study may provide potential drug targets for radiation sensitization of cancers refractive to radiation therapy.


Subject(s)
Apoptosis/drug effects , Apoptosis/radiation effects , Flavoproteins/metabolism , Gamma Rays , Membrane Proteins/metabolism , Radiation Tolerance , Reactive Oxygen Species/pharmacology , Sphingosine/analogs & derivatives , Sphingosine/pharmacology , Active Transport, Cell Nucleus/drug effects , Active Transport, Cell Nucleus/radiation effects , Apoptosis Inducing Factor , Cell Nucleus/drug effects , Cell Nucleus/metabolism , Cell Nucleus/radiation effects , Clone Cells , Combined Modality Therapy , Enzyme Activation/drug effects , Enzyme Activation/radiation effects , Humans , Intracellular Membranes/drug effects , Intracellular Membranes/metabolism , Intracellular Membranes/radiation effects , Jurkat Cells , Membrane Potentials/drug effects , Membrane Potentials/radiation effects , Mitochondria/drug effects , Mitochondria/metabolism , Mitochondria/radiation effects , Poly(ADP-ribose) Polymerases/metabolism , Proto-Oncogene Proteins c-bcl-2/metabolism , bcl-2-Associated X Protein
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