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1.
Nanotechnology ; 33(27)2022 Apr 20.
Article in English | MEDLINE | ID: mdl-35272278

ABSTRACT

In this study, we have investigated the improvements in the performance of an all-solid-state complementary electrochromic device (ECD) by using the proposed high pressure treatment (HPT). The Li:Ta2O5electrolyte layer was recrystallized by the HPT utilizing pressurized CO2gas (∼200 atm) and at low temperature (<60 °C), which enhanced the coloration performance of the WO3/Li:Ta2O5/NiO complementary ECD by ∼20%. The reliability and durability of the ECD were confirmed by long term transmittance retention measurements, which indicated an improvement in the coloration performance by ∼14% upon the release of the bias voltages. The ability of the devices that were fabricated with and without the HPT process to withstand high temperature environments was also verified. In addition, photoluminescence (PL) and transmittance measurements were carried out to examine the effects of the bonding between WO3and NiO. To determine the differences in lithium-ion (Li+) injection, electrical measurements were performed by utilizing varying pulse rising speeds to confirm device characteristics. The materials were characterized in terms of their composition and structure using high-resolution transmission electron microscopy along with energy-dispersive x-ray spectroscopy. Finally, a mechanistic model has been proposed to explain the improved EC characteristics based on the amorphous to crystalline transition accompanying the HPT process.

2.
Cancer Res ; 81(20): 5230-5241, 2021 10 15.
Article in English | MEDLINE | ID: mdl-34462276

ABSTRACT

Metastatic melanoma is challenging to clinically address. Although standard-of-care targeted therapy has high response rates in patients with BRAF-mutant melanoma, therapy relapse occurs in most cases. Intrinsically resistant melanoma cells drive therapy resistance and display molecular and biologic properties akin to neural crest-like stem cells (NCLSC) including high invasiveness, plasticity, and self-renewal capacity. The shared transcriptional programs and vulnerabilities between NCLSCs and cancer cells remains poorly understood. Here, we identify a developmental LPAR1-axis critical for NCLSC viability and melanoma cell survival. LPAR1 activity increased during progression and following acquisition of therapeutic resistance. Notably, genetic inhibition of LPAR1 potentiated BRAFi ± MEKi efficacy and ablated melanoma migration and invasion. Our data define LPAR1 as a new therapeutic target in melanoma and highlights the promise of dissecting stem cell-like pathways hijacked by tumor cells. SIGNIFICANCE: This study identifies an LPAR1-axis critical for melanoma invasion and intrinsic/acquired therapy resistance.


Subject(s)
Biomarkers, Tumor/metabolism , Drug Resistance, Neoplasm , Gene Expression Regulation, Neoplastic , Melanoma/pathology , Neural Crest/pathology , Neural Stem Cells/pathology , Receptors, Lysophosphatidic Acid/metabolism , Animals , Antineoplastic Agents/pharmacology , Apoptosis , Biomarkers, Tumor/genetics , Cell Proliferation , Humans , Melanoma/drug therapy , Melanoma/genetics , Melanoma/metabolism , Mice , Mice, Inbred NOD , Mice, SCID , Neural Crest/drug effects , Neural Crest/metabolism , Neural Stem Cells/drug effects , Neural Stem Cells/metabolism , Prognosis , Receptors, Lysophosphatidic Acid/genetics , Transcriptome , Tumor Cells, Cultured , Xenograft Model Antitumor Assays
3.
Cell Rep ; 34(2): 108628, 2021 01 12.
Article in English | MEDLINE | ID: mdl-33440148

ABSTRACT

Recent studies have profiled the innate immune signatures in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and suggest that cellular responses to viral challenge may affect disease severity. Yet the molecular events that underlie cellular recognition and response to SARS-CoV-2 infection remain to be elucidated. Here, we find that SARS-CoV-2 replication induces a delayed interferon (IFN) response in lung epithelial cells. By screening 16 putative sensors involved in sensing of RNA virus infection, we found that MDA5 and LGP2 primarily regulate IFN induction in response to SARS-CoV-2 infection. Further analyses revealed that viral intermediates specifically activate the IFN response through MDA5-mediated sensing. Additionally, we find that IRF3, IRF5, and NF-κB/p65 are the key transcription factors regulating the IFN response during SARS-CoV-2 infection. In summary, these findings provide critical insights into the molecular basis of the innate immune recognition and signaling response to SARS-CoV-2.


Subject(s)
Immunity, Innate , Interferon-Induced Helicase, IFIH1/metabolism , SARS-CoV-2/physiology , COVID-19/pathology , COVID-19/virology , Cell Line , Epithelial Cells/cytology , Epithelial Cells/immunology , Epithelial Cells/virology , Humans , Induced Pluripotent Stem Cells/cytology , Interferon Regulatory Factor-3/genetics , Interferon Regulatory Factor-3/metabolism , Interferon Regulatory Factors/genetics , Interferon Regulatory Factors/metabolism , Interferons/genetics , Interferons/metabolism , RNA Helicases/metabolism , RNA Interference , RNA, Double-Stranded/metabolism , RNA, Small Interfering/metabolism , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Signal Transduction , Transcription Factor RelA/metabolism , Virus Replication
4.
bioRxiv ; 2020 Aug 19.
Article in English | MEDLINE | ID: mdl-32839770

ABSTRACT

Disrupted antiviral immune responses are associated with severe COVID-19, the disease caused by SAR-CoV-2. Here, we show that the 73-amino-acid protein encoded by ORF9c of the viral genome contains a putative transmembrane domain, interacts with membrane proteins in multiple cellular compartments, and impairs antiviral processes in a lung epithelial cell line. Proteomic, interactome, and transcriptomic analyses, combined with bioinformatic analysis, revealed that expression of only this highly unstable small viral protein impaired interferon signaling, antigen presentation, and complement signaling, while inducing IL-6 signaling. Furthermore, we showed that interfering with ORF9c degradation by either proteasome inhibition or inhibition of the ATPase VCP blunted the effects of ORF9c. Our study indicated that ORF9c enables immune evasion and coordinates cellular changes essential for the SARS-CoV-2 life cycle. ONE-SENTENCE SUMMARY: SARS-CoV-2 ORF9c is the first human coronavirus protein localized to membrane, suppressing antiviral response, resembling full viral infection.

5.
Nanoscale Res Lett ; 14(1): 375, 2019 Dec 12.
Article in English | MEDLINE | ID: mdl-31832795

ABSTRACT

In this work, a high-density hydrogen (HDH) treatment is proposed to reduce interface traps and enhance the efficiency of the passivated emitter rear contact (PERC) device. The hydrogen gas is compressed at pressure (~ 70 atm) and relatively low temperature (~ 200 °C) to reduce interface traps without changing any other part of the device's original fabrication process. Fourier-transform infrared spectroscopy (FTIR) confirmed the enhancement of Si-H bonding and secondary-ion mass spectrometry (SIMS) confirmed the SiN/Si interface traps after the HDH treatment. In addition, electrical measurements of conductance-voltage are measured and extracted to verify the interface trap density (Dit). Moreover, short circuit current density (Jsc), series resistance (Rs), and fill factor (F.F.) are analyzed with a simulated light source of 1 kW M-2 global AM1.5 spectrum to confirm the increase in cell efficiency. External quantum efficiency (EQE) is also measured to confirm the enhancement in conversion efficiency between different wavelengths. Finally, a model is proposed to explain the experimental result before and after the treatment.

6.
iScience ; 20: 466-480, 2019 Oct 25.
Article in English | MEDLINE | ID: mdl-31627132

ABSTRACT

The cellular stress response triggers a cascade of events leading to transcriptional reprogramming and a transient inhibition of global protein synthesis, which is thought to be mediated by phosphorylation of eukaryotic initiation factor-2α (eIF2α). Using mouse embryonic fibroblasts (MEFs) and the fission yeast S. pombe, we report that rapid translational arrest and cell survival in response to hydrogen peroxide-induced oxidative stress do not rely on eIF2α kinases and eIF2α phosphorylation. Rather, H2O2 induces a block in elongation through phosphorylation of eukaryotic elongation factor 2 (eEF2). Kinetic and dose-response analyses uncovered cross talk between the eIF2α and eEF2 phosphorylation pathways, indicating that, in MEFs, eEF2 phosphorylation initiates the acute shutdown in translation, which is maintained by eIF2α phosphorylation. Our results challenge the common conception that eIF2α phosphorylation is the primary trigger of translational arrest in response to oxidative stress and point to integrated control that may facilitate the survival of cancer cells.

7.
Mol Cell ; 63(3): 514-25, 2016 08 04.
Article in English | MEDLINE | ID: mdl-27453043

ABSTRACT

An emerging therapeutic strategy for cancer is to induce selective lethality in a tumor by exploiting interactions between its driving mutations and specific drug targets. Here we use a multi-species approach to develop a resource of synthetic lethal interactions relevant to cancer therapy. First, we screen in yeast ∼169,000 potential interactions among orthologs of human tumor suppressor genes (TSG) and genes encoding drug targets across multiple genotoxic environments. Guided by the strongest signal, we evaluate thousands of TSG-drug combinations in HeLa cells, resulting in networks of conserved synthetic lethal interactions. Analysis of these networks reveals that interaction stability across environments and shared gene function increase the likelihood of observing an interaction in human cancer cells. Using these rules, we prioritize ∼10(5) human TSG-drug combinations for future follow-up. We validate interactions based on cell and/or patient survival, including topoisomerases with RAD17 and checkpoint kinases with BLM.


Subject(s)
Antineoplastic Agents/therapeutic use , Biomarkers, Tumor/genetics , Gene Regulatory Networks/drug effects , Genes, Tumor Suppressor , Mutation , Precision Medicine/methods , Protein Interaction Maps/drug effects , Saccharomyces cerevisiae/drug effects , Uterine Cervical Neoplasms/drug therapy , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Cell Proliferation/drug effects , Cell Survival/drug effects , Dose-Response Relationship, Drug , Female , Gene Expression Regulation, Fungal/drug effects , Gene Expression Regulation, Neoplastic/drug effects , Genetic Predisposition to Disease , HeLa Cells , Humans , Kaplan-Meier Estimate , Molecular Targeted Therapy , Phenotype , RNA Interference , RecQ Helicases/genetics , RecQ Helicases/metabolism , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/genetics , Saccharomyces cerevisiae Proteins/metabolism , Signal Transduction/drug effects , Synthetic Lethal Mutations , Time Factors , Transfection , Uterine Cervical Neoplasms/genetics , Uterine Cervical Neoplasms/metabolism , Uterine Cervical Neoplasms/mortality
8.
Materials (Basel) ; 9(8)2016 Aug 12.
Article in English | MEDLINE | ID: mdl-28773815

ABSTRACT

Cold forging is often applied in the fastener industry. Wires in coil form are used as semi-finished products for the production of billets. This process usually requires preliminarily drawing wire coil in order to reduce the diameter of products. The wire usually has to be annealed to improve its cold formability. The quality of spheroidizing annealed wire affects the forming quality of screws. In the fastener industry, most companies use a subcritical process for spheroidized annealing. Various parameters affect the spheroidized annealing quality of steel wire, such as the spheroidized annealing temperature, prolonged heating time, furnace cooling time and flow rate of nitrogen (protective atmosphere). The effects of the spheroidized annealing parameters affect the quality characteristics of steel wire, such as the tensile strength and hardness. A series of experimental tests on AISI 1022 low carbon steel wire are carried out and the Taguchi method is used to obtain optimum spheroidized annealing conditions to improve the mechanical properties of steel wires for cold forming. The results show that the spheroidized annealing temperature and prolonged heating time have the greatest effect on the mechanical properties of steel wires. A comparison between the results obtained using the optimum spheroidizing conditions and the measures using the original settings shows the new spheroidizing parameter settings effectively improve the performance measures over their value at the original settings. The results presented in this paper could be used as a reference for wire manufacturers.

9.
Mol Cell ; 59(2): 285-97, 2015 Jul 16.
Article in English | MEDLINE | ID: mdl-26118643

ABSTRACT

Many tumors become addicted to autophagy for survival, suggesting inhibition of autophagy as a potential broadly applicable cancer therapy. ULK1/Atg1 is the only serine/threonine kinase in the core autophagy pathway and thus represents an excellent drug target. Despite recent advances in the understanding of ULK1 activation by nutrient deprivation, how ULK1 promotes autophagy remains poorly understood. Here, we screened degenerate peptide libraries to deduce the optimal ULK1 substrate motif and discovered 15 phosphorylation sites in core autophagy proteins that were verified as in vivo ULK1 targets. We utilized these ULK1 substrates to perform a cell-based screen to identify and characterize a potent ULK1 small molecule inhibitor. The compound SBI-0206965 is a highly selective ULK1 kinase inhibitor in vitro and suppressed ULK1-mediated phosphorylation events in cells, regulating autophagy and cell survival. SBI-0206965 greatly synergized with mechanistic target of rapamycin (mTOR) inhibitors to kill tumor cells, providing a strong rationale for their combined use in the clinic.


Subject(s)
Autophagy/physiology , Benzamides/pharmacology , Intracellular Signaling Peptides and Proteins/antagonists & inhibitors , Intracellular Signaling Peptides and Proteins/metabolism , Protein Kinase Inhibitors/pharmacology , Protein Serine-Threonine Kinases/antagonists & inhibitors , Protein Serine-Threonine Kinases/metabolism , Pyrimidines/pharmacology , Amino Acid Sequence , Animals , Autophagy/drug effects , Autophagy-Related Protein-1 Homolog , Benzamides/chemistry , Catalytic Domain/genetics , Cell Survival/drug effects , Cell Survival/physiology , Cells, Cultured , Consensus Sequence , Gene Knockout Techniques , HEK293 Cells , Humans , Intracellular Signaling Peptides and Proteins/genetics , Mice , Molecular Sequence Data , Phosphorylation , Protein Kinase Inhibitors/chemistry , Protein Serine-Threonine Kinases/deficiency , Protein Serine-Threonine Kinases/genetics , Pyrimidines/chemistry , RNA, Small Interfering/genetics , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Substrate Specificity
10.
Oncotarget ; 6(26): 22060-71, 2015 Sep 08.
Article in English | MEDLINE | ID: mdl-26091350

ABSTRACT

SRC kinase is activated in castration resistant prostate cancer (CRPC), phosphorylates the androgen receptor (AR), and causes its ligand-independent activation as a transcription factor. However, activating SRC mutations are exceedingly rare in human tumors, and mechanisms of ectopic SRC activation therefore remain largely unknown. Performing a functional genomics screen, we found that downregulation of SRC inhibitory kinase CSK is sufficient to overcome growth arrest induced by depriving human prostate cancer cells of androgen. CSK knockdown led to ectopic SRC activation, increased AR signaling, and resistance to anti-androgens. Consistent with the in vitro observations, stable knockdown of CSK conferred castration resistance in mouse xenograft models, while sensitivity to the tyrosine kinase inhibitor dasatinib was retained. Finally, CSK was found downregulated in a distinct subset of CRPCs marked by AR amplification and ETS2 deletion but lacking PTEN and RB1 mutations. These results identify CSK downregulation as a principal driver of SRC activation and castration resistance and validate SRC as a drug target in a molecularly defined subclass of CRPCs.


Subject(s)
Prostatic Neoplasms, Castration-Resistant/enzymology , src-Family Kinases/metabolism , Animals , CSK Tyrosine-Protein Kinase , Cell Line, Tumor , Cell Proliferation/physiology , Down-Regulation , HEK293 Cells , Heterografts , Humans , Male , Mice , Mice, Inbred NOD , Mice, SCID , Prostatic Neoplasms, Castration-Resistant/genetics , Prostatic Neoplasms, Castration-Resistant/pathology , Signal Transduction , Transfection , Xenograft Model Antitumor Assays , src-Family Kinases/genetics
11.
F1000Res ; 3: 115, 2014.
Article in English | MEDLINE | ID: mdl-25177484

ABSTRACT

NKX3.1 is a homeobox transcription factor whose function as a prostate tumor suppressor remains insufficiently understood because neither the transcriptional program governed by NKX3.1, nor its interacting proteins have been fully revealed. Using affinity purification and mass spectrometry, we have established an extensive NKX3.1 interactome which contains the DNA repair proteins Ku70, Ku80, and PARP, thus providing a molecular underpinning to previous reports implicating NKX3.1 in DNA repair. Transcriptomic profiling of NKX3.1-negative prostate epithelial cells acutely expressing NKX3.1 revealed a rapid and complex response that is a near mirror image of the gene expression signature of human prostatic intraepithelial neoplasia (PIN). Pathway and network analyses suggested that NKX3.1 actuates a cellular reprogramming toward luminal cell differentiation characterized by suppression of pro-oncogenic c-MYC and interferon-STAT signaling and activation of tumor suppressor pathways. Consistently, ectopic expression of NKX3.1 conferred a growth arrest depending on TNFα and JNK signaling. We propose that the tumor suppressor function of NKX3.1 entails a transcriptional program that maintains the differentiation state of secretory luminal cells and that disruption of NKX3.1 contributes to prostate tumorigenesis by permitting luminal cell de-differentiation potentially augmented by defects in DNA repair.

12.
ScientificWorldJournal ; 2013: 403978, 2013.
Article in English | MEDLINE | ID: mdl-24391461

ABSTRACT

This study investigates how to adjust the transmit power of femto base station (FBS) to mitigate interference problems between the FBSs and mobile users (MUs) in the 2-tier heterogeneous femtocell networks. A common baseline of deploying the FBS to increase the indoor access bandwidth requires that the FBS operation will not affect outdoor MUs operation with their quality-of-service (QoS) requirements. To tackle this technical problem, an FBS transmit power adjustment (FTPA) algorithm is proposed to adjust the FBS transmit power (FTP) to avoid unwanted cochannel interference (CCI) with the neighboring MUs in downlink transmission. FTPA reduces the FTP to serve its femto users (FUs) according to the QoS requirements of the nearest neighboring MUs to the FBS so that the MU QoS requirement is guaranteed. Simulation results demonstrate that FTPA can achieve a low MU outage probability as well as serve FUs without violating the MU QoS requirements. Simulation results also reveal that FTPA has better performance on voice and video services which are the major trend of future multimedia communication in the NGN.


Subject(s)
Algorithms , Cell Phone/instrumentation , Electric Power Supplies , Electronics/methods , Models, Theoretical , Signal Processing, Computer-Assisted , Wireless Technology/instrumentation
13.
Opt Express ; 19 Suppl 4: A740-6, 2011 Jul 04.
Article in English | MEDLINE | ID: mdl-21747542

ABSTRACT

A 25-pixel illumination system composed of a 5 × 5 dielectric liquid-lens (DLL) zoom module array, 25 light-emission diodes (LEDs), and a secondary optical lens demonstrates 3D light field manipulation. LEDs function as 2D illumination pixels while the DLL module array performs longitudinal illuminance adjustability by zooming each illumination pixel. A test on the similarity of two illuminance patterns between experiments and simulations shows a normalized cross correlation (NCC) higher than 0.8, indicating the feasibility of the system design. Also, the illumination system is further applied to correct a distorted light pattern on a 45° tilt screen as well as to perform light compensation on distance-differential objects.

14.
BMC Biol ; 8: 153, 2010 Dec 23.
Article in English | MEDLINE | ID: mdl-21182779

ABSTRACT

BACKGROUND: The cyclin-dependent kinase (CDK) inhibitor p27(Kip)¹ is downregulated in a majority of human cancers due to ectopic proteolysis by the ubiquitin-proteasome pathway. The expression of p27 is subject to multiple mechanisms of control involving several transcription factors, kinase pathways and at least three different ubiquitin ligases (SCF(SKP)², KPC, Pirh2), which regulate p27 transcription, translation, protein stability and subcellular localization. Using a chemical genetics approach, we have asked whether this control network can be modulated by small molecules such that p27 protein expression is restored in cancer cells. RESULTS: We developed a cell-based assay for measuring the levels of endogenous nuclear p27 in a high throughput screening format employing LNCaP prostate cancer cells engineered to overexpress SKP2. The assay platform was optimized to Z' factors of 0.48 - 0.6 and piloted by screening a total of 7368 chemical compounds. During the course of this work, we discovered two small molecules of previously unknown biological activity, SMIP001 and SMIP004, which increase the nuclear level of p27 at low micromolar concentrations. SMIPs (small molecule inhibitors of p27 depletion) also upregulate p21(Cip)¹, inhibit cellular CDK2 activity, induce G1 delay, inhibit colony formation in soft agar and exhibit preferential cytotoxicity in LNCaP cells relative to normal human fibroblasts. Unlike SMIP001, SMIP004 was found to downregulate SKP2 and to stabilize p27, although neither SMIP is a proteasome inhibitor. Whereas the screening endpoint - nuclear p27 - was robustly modulated by the compounds, SMIP-mediated cell cycle arrest and apoptosis were not strictly dependent on p27 and p21 - a finding that is explained by parallel inhibitory effects of SMIPs on positive cell cycle regulators, including cyclins E and A, and CDK4. CONCLUSIONS: Our data provide proof-of-principle that the screening platform we developed, using endogenous nuclear p27 as an endpoint, presents an effective means of identifying bioactive molecules with cancer selective antiproliferative activity. This approach, when applied to larger and more diverse sets of compounds with refined drug-like properties, bears the potential of revealing both unknown cellular pathways globally impinging on p27 and novel leads for chemotherapeutics targeting a prominent molecular defect of human cancers.


Subject(s)
Antineoplastic Agents/pharmacology , Carcinoma/drug therapy , Cell Proliferation/drug effects , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Prostatic Neoplasms/drug therapy , Antineoplastic Agents/isolation & purification , Antineoplastic Agents/therapeutic use , Carcinoma/genetics , Carcinoma/metabolism , Carcinoma/pathology , Cyclin-Dependent Kinase Inhibitor p27 , Drug Screening Assays, Antitumor/methods , Gene Expression Regulation, Neoplastic/drug effects , HeLa Cells , High-Throughput Screening Assays/methods , Humans , Intracellular Signaling Peptides and Proteins/physiology , Male , Molecular Targeted Therapy , Prostatic Neoplasms/genetics , Prostatic Neoplasms/metabolism , Prostatic Neoplasms/pathology , Protein Processing, Post-Translational/drug effects , S-Phase Kinase-Associated Proteins/genetics , S-Phase Kinase-Associated Proteins/metabolism , S-Phase Kinase-Associated Proteins/physiology , Tumor Cells, Cultured , Up-Regulation/drug effects
15.
Biomicrofluidics ; 4(4): 43006, 2010 Dec 30.
Article in English | MEDLINE | ID: mdl-21267438

ABSTRACT

This study presents packaged microscale liquid lenses actuated with liquid droplets of 300-700 µm in diameter using the dielectric force manipulation. The liquid microlens demonstrated function focal length tunability in a plastic package. The focal length of the liquid lens with a lens droplet of 500 µm in diameter is shortened from 4.4 to 2.2 mm when voltages applied change from 0 to 79 V(rms). Dynamic responses that are analyzed using 2000 frames∕s high speed motion cameras show that the advancing and receding times are measured to be 90 and 60 ms, respectively. The size effect of dielectric liquid microlens is characterized for a lens droplet of 300-700 µm in diameter in an aspect of focal length.

16.
Cancer Cell ; 15(5): 355-7, 2009 May 05.
Article in English | MEDLINE | ID: mdl-19411063

ABSTRACT

Macrophage infiltration and inflammatory cytokines are powerful drivers of tumorigenesis and metastasis. Wu et al., in this issue of Cancer Cell, show that TNFalpha-dependent NFkappaB activation induces COP9 signalosome-mediated inhibition of GSK3beta and the SCF(beta-TRCP) ubiquitin ligase, thus leading to stabilization of the transcription factor Snail and promoting cell migration and metastasis.


Subject(s)
Cell Transformation, Neoplastic/metabolism , Neoplasm Metastasis , Animals , COP9 Signalosome Complex , Cell Movement/physiology , Glycogen Synthase Kinase 3/antagonists & inhibitors , Glycogen Synthase Kinase 3 beta , Humans , Inflammation/metabolism , Macrophages/metabolism , Macrophages/pathology , Multiprotein Complexes/metabolism , NF-kappa B/metabolism , Peptide Hydrolases/metabolism , SKP Cullin F-Box Protein Ligases/antagonists & inhibitors , Signal Transduction , Snail Family Transcription Factors , Transcription Factors/metabolism , Tumor Necrosis Factor-alpha/metabolism
17.
J Phys Chem B ; 112(30): 9165-73, 2008 Jul 31.
Article in English | MEDLINE | ID: mdl-18598074

ABSTRACT

Exocytosis of a single bovine adrenal chromaffin cell, triggered by histamine stimulation, was investigated via the electric responses detected with single-walled carbon-nanotube field-effect transistors (SWCNT-FET) and the morphological changes acquired by atomic force microscopy (AFM). Secretion of chromogranin A (CgA), stored in the vesicles of a single chromaffin cell, can be monitored in situ by the antibody against CgA (CgA-antibody) functionalized on the SWCNT-FET devices. The SWCNT-FET can further discriminate the amount of released CgA with different levels of histamine stimulations. The AFM morphological studies on a chromaffin cell indicate that the depression structures on the cell surface, caused by the histamine-evoked exocytotic fusion pores, appeared much more frequently than those without histamine stimulation or with the pretreatment of mepyramine before histamine stimulation. The vesicle diameters are about 50 nm calculated from the obtained three-dimensional AFM images. In comparison, the fusion pores of chromaffin cells stimulated by high-K (+) buffer solution were also investigated to have a wider-ranging distribution of vesicle diameters of 60-260 nm. This work demonstrates that the combination of novel techniques, SWCNT-FET and AFM, can provide further insights into the fundamental properties of exocytosis in neuroendocrine cells.


Subject(s)
Adrenal Glands/cytology , Chromaffin Cells/cytology , Chromaffin Cells/metabolism , Exocytosis , Animals , Cattle , Cell Membrane/metabolism , Chromogranin A/metabolism , Electrophysiology , Microscopy, Atomic Force , Porosity , Secretory Vesicles/metabolism , Transistors, Electronic
18.
Cancer Res ; 68(8): 2820-30, 2008 Apr 15.
Article in English | MEDLINE | ID: mdl-18413750

ABSTRACT

Preexisting and acquired resistance to epidermal growth factor receptor (EGFR) inhibitors limits their clinical usefulness in patients with advanced non-small cell lung cancer (NSCLC). This study characterizes the efficacy and mechanisms of the combination of gefitinib or erlotinib with OSU-03012, a celecoxib-derived antitumor agent, to overcome EGFR inhibitor resistance in three NSCLC cell lines, H1155, H23, and A549. The OSU-03012/EGFR inhibitor combination induced pronounced apoptosis in H1155 and H23 cells, but not in A549 cells, suggesting a correlation between drug sensitivity and basal phospho-Akt levels independently of EGFR expression status. Evidence indicates that this combination facilitates apoptosis through both Akt signaling inhibition and up-regulation of endoplasmic reticulum (ER) stress-induced, GADD153-mediated pathways. For example, ectopic expression of constitutively active Akt significantly attenuated the inhibitory effect on cell survival, and small interfering RNA-mediated knockdown of GADD153 protected cells from undergoing apoptosis in response to drug cotreatments. Furthermore, the OSU-03012/EGFR inhibitor combination induced GADD153-mediated up-regulation of death receptor 5 expression and subsequent activation of the extrinsic apoptosis pathway. It is noteworthy that the ER stress response induced by this combination was atypical in that the cytoprotective pathway was not engaged. In addition, in vivo suppression of tumor growth and modulation of intratumoral biomarkers were observed in a H1155 tumor xenograft model in nude mice. These data suggest that the concomitant modulation of Akt and ER stress pathways with the OSU-03012/EGFR inhibitor combination represents a unique approach to overcoming EGFR inhibitor resistance in NSCLC and perhaps other types of cancer with elevated basal Akt activities.


Subject(s)
Endoplasmic Reticulum/physiology , ErbB Receptors/antagonists & inhibitors , Proto-Oncogene Proteins c-akt/metabolism , Pyrazoles/pharmacology , Quinazolines/pharmacology , Sulfonamides/pharmacology , Actins/genetics , Antineoplastic Agents/pharmacology , Carcinoma, Non-Small-Cell Lung , Cell Line, Tumor , Cell Survival/drug effects , Endoplasmic Reticulum/drug effects , Erlotinib Hydrochloride , Flow Cytometry , Gefitinib , Humans , Lung Neoplasms , Proto-Oncogene Proteins c-akt/drug effects , Receptors, TNF-Related Apoptosis-Inducing Ligand/genetics , Reverse Transcriptase Polymerase Chain Reaction
19.
J Biomed Sci ; 15(2): 169-81, 2008 Mar.
Article in English | MEDLINE | ID: mdl-17960496

ABSTRACT

Calcium binding protein-1 (CaBP1) is a calmodulin like protein shown to modulate Ca2+ channel activities. Here, we explored the functions of long and short spliced CaBP1 variants (L- and S-CaBP1) in modulating stimulus-secretion coupling in primary cultured bovine chromaffin cells. L- and S-CaBP1 were cloned from rat brain and fused with yellow fluorescent protein at the C-terminal. When expressed in chromaffin cells, wild-type L- and S-CaBP1s could be found in the cytosol, plasma membrane and a perinuclear region; in contrast, the myristoylation-deficient mutants were not found in the membrane. More than 20 and 70% of Na+ and Ca2+ currents, respectively, were inhibited by wild-type isoforms but not myristoylation-deficient mutants. The [Ca2+]( i ) response evoked by high K+ buffer and the exocytosis elicited by membrane depolarizations were inhibited only by wild-type isoforms. Neuronal Ca2+ sensor-1 and CaBP5, both are calmodulin-like proteins, did not affect N(+, Ca2+ currents, and exocytosis. When expressed in cultured cortical neurons, the [Ca2+]( i ) responses elicited by high-K+ depolarization were inhibited by CaBP1 isoforms. In HEK293T cells cotransfected with N-type Ca2+ channel and L-CaBP1, the current was reduced and activation curve was shifted positively. These results demonstrate the importance of CaBP1s in modulating the stimulus-secretion coupling in excitable cells.


Subject(s)
Calcium-Binding Proteins/metabolism , Cell Membrane/metabolism , Chromaffin Cells/metabolism , Exocytosis/physiology , Membrane Potentials/physiology , Animals , Calcium/metabolism , Calcium-Binding Proteins/genetics , Cattle , Cell Line , Cell Membrane/genetics , Cerebral Cortex/physiology , Chromaffin Cells/cytology , Embryo, Mammalian/cytology , Embryo, Mammalian/metabolism , Female , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Humans , Mutation , Myristates/metabolism , Neurons/cytology , Neurons/metabolism , Potassium/metabolism , Protein Isoforms/genetics , Protein Isoforms/metabolism , Protein Processing, Post-Translational/physiology , Rats , Rats, Sprague-Dawley , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Sodium/metabolism
20.
Cancer Res ; 67(11): 5318-27, 2007 Jun 01.
Article in English | MEDLINE | ID: mdl-17545612

ABSTRACT

This study reports a histone deacetylation-independent mechanism whereby histone deacetylase (HDAC) inhibitors sensitize prostate cancer cells to DNA-damaging agents by targeting Ku70 acetylation. Ku70 represents a crucial component of the nonhomologous end joining repair machinery for DNA double-strand breaks (DSB). Our data indicate that pretreatment of prostate cancer cells with HDAC inhibitors (trichostatin A, suberoylanilide hydroxamic acid, MS-275, and OSU-HDAC42) led to increased Ku70 acetylation accompanied by reduced DNA-binding affinity without disrupting the Ku70/Ku80 heterodimer formation. As evidenced by increased Ser(139)-phosphorylated histone H2AX (gammaH2AX), impaired Ku70 function diminished cellular capability to repair DNA DSBs induced by bleomycin, doxorubicin, and etoposide, thereby enhancing their cell-killing effect. This sensitizing effect was most prominent when cells were treated with HDAC inhibitors and DNA-damaging agents sequentially. Mimicking acetylation was done by replacing K282, K317, K331, K338, K539, or K542 with glutamine via site-directed mutagenesis, which combined with computer docking analysis was used to analyze the role of these lysine residues in the interactions of Ku70 with DNA broken ends. Mutagenesis of K282, K338, K539, or K542 suppressed the activity of Ku70 to bind DNA, whereas mutagenesis of K317 or K331 with glutamine had no significant effect. Moreover, overexpression of K282Q or K338Q rendered DU-145 cells more susceptible to the effect of DNA-damaging agents on gammaH2AX formation and cell killing. Overall, the ability of HDAC inhibitors to regulate cellular ability to repair DNA damage by targeting Ku70 acetylation underlies the viability of their combination with DNA-damaging agents as a therapeutic strategy for prostate cancer.


Subject(s)
Antigens, Nuclear/metabolism , Antineoplastic Agents/pharmacology , DNA Breaks, Double-Stranded , DNA-Binding Proteins/metabolism , Enzyme Inhibitors/pharmacology , Histone Deacetylase Inhibitors , Prostatic Neoplasms/drug therapy , Acetylation , DNA Repair/drug effects , DNA Repair/physiology , DNA, Neoplasm/drug effects , DNA, Neoplasm/metabolism , Drug Synergism , Humans , Ku Autoantigen , Male , Models, Molecular , Prostatic Neoplasms/enzymology , Prostatic Neoplasms/genetics
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