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1.
Phys Rev Lett ; 132(4): 041801, 2024 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-38335355

RESUMO

We present the first search for heavy neutral leptons (HNLs) decaying into νe^{+}e^{-} or νπ^{0} final states in a liquid-argon time projection chamber using data collected with the MicroBooNE detector. The data were recorded synchronously with the NuMI neutrino beam from Fermilab's main injector corresponding to a total exposure of 7.01×10^{20} protons on target. We set upper limits at the 90% confidence level on the mixing parameter |U_{µ4}|^{2} in the mass ranges 10≤m_{HNL}≤150 MeV for the νe^{+}e^{-} channel and 150≤m_{HNL}≤245 MeV for the νπ^{0} channel, assuming |U_{e4}|^{2}=|U_{τ4}|^{2}=0. These limits represent the most stringent constraints in the mass range 35

2.
Eur Phys J C Part Fields ; 83(9): 782, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37680254

RESUMO

The T2K experiment presents new measurements of neutrino oscillation parameters using 19.7(16.3)×1020 protons on target (POT) in (anti-)neutrino mode at the far detector (FD). Compared to the previous analysis, an additional 4.7×1020 POT neutrino data was collected at the FD. Significant improvements were made to the analysis methodology, with the near-detector analysis introducing new selections and using more than double the data. Additionally, this is the first T2K oscillation analysis to use NA61/SHINE data on a replica of the T2K target to tune the neutrino flux model, and the neutrino interaction model was improved to include new nuclear effects and calculations. Frequentist and Bayesian analyses are presented, including results on sin2θ13 and the impact of priors on the δCP measurement. Both analyses prefer the normal mass ordering and upper octant of sin2θ23 with a nearly maximally CP-violating phase. Assuming the normal ordering and using the constraint on sin2θ13 from reactors, sin2θ23=0.561-0.032+0.021 using Feldman-Cousins corrected intervals, and Δm322=2.494-0.058+0.041×10-3eV2 using constant Δχ2 intervals. The CP-violating phase is constrained to δCP=-1.97-0.70+0.97 using Feldman-Cousins corrected intervals, and δCP=0,π is excluded at more than 90% confidence level. A Jarlskog invariant of zero is excluded at more than 2σ credible level using a flat prior in δCP, and just below 2σ using a flat prior in sinδCP. When the external constraint on sin2θ13 is removed, sin2θ13=28.0-6.5+2.8×10-3, in agreement with measurements from reactor experiments. These results are consistent with previous T2K analyses.

3.
Soft Matter ; 18(27): 5089-5096, 2022 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-35766018

RESUMO

Whilst it is highly desirable to produce artificial lipid bilayer arrays allowing for systematic high-content screening of membrane conditions, it remains a challenge due to the combined requirements of scaled membrane production, simple measurement access, and independent control over individual bilayer experimental conditions. Here, droplet bilayers encapsulated within a hydrogel shell are output individually into multi-well plates for simple, arrayed quantitative measurements. The afforded experimental throughput is used to conduct a 2D concentration screen characterising the synergistic pore-forming peptides Magainin2 and PGLa. Maximal enhanced activity is revealed at equimolar peptide concentrations via a membrane dye leakage assay, a finding consistent with models proposed from NMR data. The versatility of the platform is demonstrated by performing in situ electrophysiology, revealing low conductance pore activity (∼15 to 20 pA with 4.5 pA sub-states). In conclusion, this array platform addresses the aforementioned challenges and provides new and flexible opportunities for high-throughput membrane studies. Furthermore, the ability to engineer droplet networks within each construct paves the way for "lab-in-a-capsule" approaches accommodating multiple assays per construct and allowing for communicative reaction pathways.


Assuntos
Bicamadas Lipídicas , Transporte Biológico , Bicamadas Lipídicas/química , Espectroscopia de Ressonância Magnética , Membranas
4.
Phys Rev Lett ; 124(16): 161802, 2020 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-32383902

RESUMO

Electron antineutrino appearance is measured by the T2K experiment in an accelerator-produced antineutrino beam, using additional neutrino beam operation to constrain parameters of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix. T2K observes 15 candidate electron antineutrino events with a background expectation of 9.3 events. Including information from the kinematic distribution of observed events, the hypothesis of no electron antineutrino appearance is disfavored with a significance of 2.40σ and no discrepancy between data and PMNS predictions is found. A complementary analysis that introduces an additional free parameter which allows non-PMNS values of electron neutrino and antineutrino appearance also finds no discrepancy between data and PMNS predictions.

5.
Osteoarthritis Cartilage ; 26(9): 1257-1261, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29723633

RESUMO

OBJECTIVE: Our study analyzes the association between chemokine-ligand-2 (CCL2) serum concentrations at baseline and knee radiographic osteoarthritis (OA) (knee-rOA), knee-rOA progression, individual radiographic features and knee symptomatic OA at 5-year follow-up. DESIGN: OA outcomes were analyzed in a community-based cohort including a baseline enrollment and a 5-year follow-up. Baseline CCL2 serum concentrations were assessed by multiplex assay and associated with presence or progression of individual radiographic features at 5-year follow-up. Separate multiple logistic regression models were used to examine adjusted associations between baseline CCL2 and each of the knee OA variables at follow-up. CCL2 at baseline was modeled as an explanatory variable, whereas each of the knee OA variables at follow-up served as the response variables. Models were adjusted for age, BMI, race, and sex. Trend tests were conducted to assess any linear effect on outcomes across CCL2 tertiles. RESULTS: Participants (n = 168) had a median age of 57-years and median BMI of 29 kg/m2. About 63% of all participants were women, and 58% Caucasian (42% African American). In adjusted logistic models, continuous log-CCL2 was significantly associated with knee-rOA. For each unit increase in log CCL2, the odds of having knee-rOA at follow-up was increased by 72%. CCL2 tertiles showed significant linear associations with presence and progression of knee-rOA and medial joint space narrowing (JSN), but not with presence or progression of osteophytes, bone sclerosis, knee symptoms, or symptomatic knee-rOA. CONCLUSIONS: Serum CCL2 may help to elucidate some mechanisms of joint destruction and identify individuals with higher odds of structural knee changes.


Assuntos
Quimiocina CCL2/sangue , Progressão da Doença , Osteoartrite do Joelho/sangue , Osteoartrite do Joelho/diagnóstico por imagem , Idoso , Biomarcadores/sangue , Estudos de Coortes , Feminino , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Osteoartrite do Joelho/fisiopatologia , Prognóstico , Radiografia/métodos , Sensibilidade e Especificidade , Índice de Gravidade de Doença
6.
Neurogastroenterol Motil ; 30(10): e13378, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29797382

RESUMO

BACKGROUND: Serum levels of pro-inflammatory cytokines tend to be increased in irritable bowel syndrome (IBS) patients, or subgroups thereof. Still, the link between cytokine levels and IBS symptoms is unclear. We aim to determine systemic cytokine levels in IBS patients and healthy subjects (HS), confirm the presence of a subset of patients with an increased immune activity and to establish if cytokines are linked to IBS symptoms and pathophysiological factors. METHODS: Serum levels of interleukin (IL)-1ß, IL-6, IL-8, tumor necrosis factor (TNF), and IL-10 were measured. All subjects reported IBS symptoms using validated questionnaires and underwent colonic sensorimotor testing. Multivariate supervised orthogonal partial least squares-discriminant analysis (OPLS-DA) and unsupervised principal component analysis (PCA) and hierarchical cluster analysis (HCA) were implemented. KEY RESULTS: Irritable bowel syndrome patients (n = 246) had higher serum levels of IL-1ß, IL-6, IL-8, TNF, and IL-10 compared to HS (n = 21); however, serum cytokine profiles could not discriminate patients from HS. Moreover, cytokine levels were not correlated with symptoms among patients. Supervised OPLS-DA identified 104 patients (40% of patients) and unsupervised HCA analysis identified 49 patients (20%) with an increased immune activity indicated by elevated levels of serum cytokines compared to HS and the other patients. However, irrespective of how patients with increased immune activity were identified they were symptomatically similar to patients with no indication of increased immune activity. CONCLUSIONS & INFERENCES: Serum cytokines are elevated in IBS patients compared to HS. Immune activation characterizes a subset of patients, but modest associations between cytokine profile and symptoms suggest immune activity does not directly influence symptoms in IBS.


Assuntos
Citocinas/sangue , Síndrome do Intestino Irritável/sangue , Síndrome do Intestino Irritável/imunologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
7.
Opt Express ; 26(10): 13436-13442, 2018 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-29801369

RESUMO

Aspheric astigmatic polymer micro-lenses were fabricated directly onto photonic integrated circuits using two-photon lithography. We observed a 12.6 dB improvement in the free space coupling efficiency between integrated ridge laser pairs with micro-lenses to those without.

8.
Opt Express ; 25(20): 23634-23644, 2017 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-29041314

RESUMO

Chip based particle sensing using 3D capillary fill microfluidics integrated with monolithically integrated lasers and photodetectors is used to demonstrate the feasibility of true chip scale photonic measurements of fluids. The approach is scalable and manufactured using industry standard compound semiconductor fabrication tools. The need for fluid speed regulation via external pumps is removed by measuring local particle velocity at the point of interrogation and particle position within the fluid flow is derived from multiple time resolved forward scattered light signals. Particle size discrimination of 10 and 15 µm polystyrene microbeads is used as an example.

9.
Lab Chip ; 17(16): 2873-2881, 2017 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-28731104

RESUMO

A new oscillatory microfluidic junction is described, which enables the consistent formation of highly uniform and complex double emulsions, and is demonstrated for the encapsulation of four different reagents within the inner droplets (called cores) of the double emulsion droplets. Once the double emulsion droplets had attained a spherical form, the cores assumed specific 3D arrangements, the orchestration of which appeared to depend upon the specific emulsion morphology. Such double emulsion droplets were used as templates to produce highly compartmentalised microcapsules and multisomes. Based on these construct models, we numerically demonstrated a model chemical reaction sequence between and within the liquid cores. This work could provide a platform to perform space/time-dependent applications, such as programmed experiments, synthesis, and delivery systems.


Assuntos
Composição de Medicamentos/instrumentação , Técnicas Analíticas Microfluídicas/instrumentação , Desenho de Equipamento , Modelos Químicos
10.
J Chromatogr A ; 1218(15): 1983-7, 2011 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-21241990

RESUMO

We report the first development of a novel, planar, microfluidic, graphitic carbon separations column utilizing an array of graphitic micropillars of diamond cross-section as the chromatographic stationary phase. 795 nm femtosecond laser ablation was employed to subtractively machine fluidic architectures and a micropillared array in a planar, graphitic substrate as a monolithic structure. A sample injector was integrated on-chip, together with fluid-flow distribution architectures to minimize band-broadening and ensure sample equi-distribution across the micro-pillared column width. The separations chip was interfaced directly to the ESI probe of a Thermofisher Surveyor mass spectrometer, enabling the detection of test-mixture analytes following their differential retention on the micro-pillared graphitic column, thus demonstrating the exciting potential of this novel separations format. Importantly, unlike porous, graphitic microspheres, the temperature and pressure resilience of the microfluidic device potentially enables use in subcritical H(2)O chromatography.


Assuntos
Cromatografia Líquida de Alta Pressão/instrumentação , Grafite/química , Acrilamida/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Hidrocortisona/isolamento & purificação , Técnicas Analíticas Microfluídicas , Espectrometria de Massas por Ionização por Electrospray
11.
Postgrad Med J ; 83(985): 717-21, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17989272

RESUMO

OBJECTIVE: To study the effect of Tai Chi on exercise tolerance in patients with moderate heart failure. DESIGN: Randomised parallel group study balanced for baseline variables. SETTING: Cardiology Department, Royal Hallamshire Hospital. PATIENTS AND METHODS: 52 patients (42 men, mean age (68.9 years), range (46-90 years), and 10 women, mean age (70.0 years), range (58-82)) with chronic heart failure (New York Heart Association symptom class II-III) were studied. Patients were randomised to Tai Chi Chuan twice a week for 16 weeks or to standard medical care without exercise rehabilitation. MAIN OUTCOME MEASURES: The primary outcome measure was the change in the distance walked in the shuttle walk test. Secondary outcome measures were changes in symptom scores and quality of life indices. RESULTS: Objective measures of exercise tolerance did not improve significantly with Tai Chi, but patients having Tai Chi exercise had an improvement in symptom scores of heart failure measured by the Minnesota Living with Heart Failure Questionnaire (comparison of deltas, -2.4 control vs -14.9; p = 0.01), and depression scores measured by the SCL-90-R questionnaire (-2.9 vs -6.8; p = 0.12) compared with those patients in the control group. CONCLUSION: In patients with chronic heart failure, 16 weeks of Tai Chi training was safe, with no adverse exercise related problems. It was enjoyed by all taking part and led to significant improvements in symptoms and quality of life.


Assuntos
Insuficiência Cardíaca/terapia , Tai Chi Chuan , Idoso , Cardiotônicos/uso terapêutico , Feminino , Humanos , Masculino , Projetos Piloto , Tai Chi Chuan/efeitos adversos , Resultado do Tratamento
12.
Br J Cancer ; 95(2): 172-80, 2006 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-16819546

RESUMO

Resistance to antiepidermal growth factor (EGFR) strategies is an emerging clinical problem. Using human colorectal cancer (CRC) cells, we evaluated the involvement of the insulin receptor isoform-A (InsR-A) in de novo resistance to gefitinib, an EGFR tyrosine kinase inhibitor. Challenging the EGFR positive LoVo cells with gefitinib (1 microM) resulted in a small ( approximately 18%) inhibition of cell growth and although a modest reduction in phospho (p)EGFR Tyr845 was seen, pEGFR at residues -Tyr1068 and -Tyr1173 were unchanged. LoVo cells produced unprocessed pro-IGF-1R protein, substantial levels of IGF-II mRNA and mature InsR protein, consisting mainly of the InsR-A isoform. Insulin and IGF-II promoted cell growth and pEGFR Tyr845, Tyr1068 and Tyr1173 activity and conversely, the insulin-like growth factor-1 receptor (IGF-1R)/InsR inhibitor ABDP (1 muM) inhibited growth and reduced pEGFR activity at all three tyrosine residues. pInsR and pAkt levels were increased after gefitinib treatment. Blocking of pInsR with ABDP enabled gefitinib to markedly reduce pEGFR Tyr845, Tyr1068 and Tyr1173. Short-term gefitinib/ABDP dual treatment was more effective than either agent alone and chronic exposure to this combination resulted in total cell loss after 9 weeks, preventing acquisition of resistance to ABDP. LoVo cells with acquired resistance to ABDP were acutely sensitive to gefitinib. We concluded that InsR-A reduces sensitivity to gefitinib in LoVo CRC cells, thus its co-targeting alongside EGFR can improve the anti-tumour effect of gefitinib.


Assuntos
Neoplasias do Colo/tratamento farmacológico , Resistencia a Medicamentos Antineoplásicos , Quinazolinas/farmacologia , Receptor de Insulina/antagonistas & inibidores , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Difosfonatos/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Receptores ErbB/antagonistas & inibidores , Receptores ErbB/metabolismo , Gefitinibe , Humanos , Insulina/farmacologia , Fator de Crescimento Insulin-Like II/farmacologia , Fosforilação , Isoformas de Proteínas/antagonistas & inibidores , Isoformas de Proteínas/biossíntese , RNA Mensageiro/biossíntese , Receptor IGF Tipo 1/biossíntese , Receptor de Insulina/biossíntese , Transdução de Sinais/efeitos dos fármacos , Células Tumorais Cultivadas
13.
Breast Cancer Res Treat ; 96(2): 131-46, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16261397

RESUMO

We have previously demonstrated that oestrogen receptor alpha (ERalpha) modulates epidermal growth factor receptor (EGFR)/mitogen-activated protein kinase (MAPK) signalling efficiency in a tamoxifen-resistant MCF-7 breast cancer cell line (Tam-R). In the present study we have investigated whether this cross-talk between EGFR/MAPK and ERalpha signalling pathways is bidirectional by examining the effects of EGFR/MAPK activity on ER functionality in the same cell line. Elevated expression levels of phosphorylated serine 118 (S118) ERalpha were observed in the Tam-R compared to the parental wild type MCF-7 cell line (WT-MCF-7) under basal growth conditions. Phosphorylation of ERalpha at S118 was regulated by the EGFR/MAPK pathway in Tam-R cells being increased in response to amphiregulin (AR) and inhibited by the selective EGFR tyrosine kinase inhibitor, gefitinib and the MEK1/2 inhibitor, PD184352. Recruitment of the co-activators p68 RNA helicase and SRC1 to ERalpha, oestrogen response element (ERE) activity and Tam-R cell growth were similarly EGFR/MAPK-regulated. Chromatin immunoprecipitation (ChIP) studies revealed that in Tam-R cells the ERalpha assembled on the AR gene promoter and this was associated with elevated basal expression of AR mRNA. Furthermore, AR mRNA expression was under the regulation of the EGFR/MAPK and ERalpha signalling pathways. Neutralising antibodies to AR inhibited EGFR/ERK1/2 activity, reduced S118 ERalpha phosphorylation and reduced AR mRNA expression in TAM-R cells. These findings suggest that ERalpha function in Tam-R cells is maintained as a consequence of EGFR/MAPK-mediated phosphorylation at serine residue 118 resulting in the generation of a self-propogating autocrine growth-regulatory loop through the ERalpha-mediated production of AR.


Assuntos
Antineoplásicos Hormonais/farmacologia , Neoplasias da Mama/patologia , Resistencia a Medicamentos Antineoplásicos , Receptores ErbB/metabolismo , Moduladores de Receptor Estrogênico/farmacologia , Receptores de Estrogênio/metabolismo , Transdução de Sinais , Tamoxifeno/farmacologia , Western Blotting , Neoplasias da Mama/tratamento farmacológico , Linhagem Celular Tumoral , Feminino , Humanos , Imuno-Histoquímica , Reação em Cadeia da Polimerase Via Transcriptase Reversa
14.
Endocr Relat Cancer ; 12 Suppl 1: S173-82, 2005 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16113094

RESUMO

Aberrant signalling through the epidermal growth factor receptor (EGFR) is associated with increased cancer cell proliferation, reduced apoptosis, invasion and angiogenesis. Over-expression of the EGFR is seen in a variety of tumours and is a rational target for antitumour strategies. Among the classes of agent targeting the EGFR are small-molecule inhibitors, which include gefitinib (IRESSA), which acts by preventing EGFR phosphorylation and downstream signal transduction. De novo and acquired resistance, however, have been reported to gefitinib and here we describe evidence which indicates that the type II receptor tyrosine kinases (RTKs) insulin-like growth factor-I receptor (IGF-IR) and/or insulin receptor (InsR) play important roles in the mediation of responses to gefitinib in the de novo- and acquired-resistance phenotypes in several cancer types. Moreover, combination strategies that additionally target the IGF-IR/InsR can enhance the antitumour effects of gefitinib.


Assuntos
Antineoplásicos/uso terapêutico , Receptores ErbB/antagonistas & inibidores , Neoplasias/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêutico , Quinazolinas/uso terapêutico , Antineoplásicos/farmacologia , Proliferação de Células , Resistencia a Medicamentos Antineoplásicos , Gefitinibe , Humanos , Inibidores de Proteínas Quinases/farmacologia , Quinazolinas/farmacologia , Transdução de Sinais/efeitos dos fármacos
15.
Endocr Relat Cancer ; 12 Suppl 1: S29-36, 2005 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16113097

RESUMO

De novo insensitivity and acquired resistance to the selective oestrogen receptor modulator tamoxifen and the pure anti-oestrogen fulvestrant (faslodex) severely limit their effectiveness in breast cancer patients. This is a major clinical problem, since each year upward of 1 million women are dispensed anti-oestrogenic drugs. In order to investigate the phenomenon of anti-oestrogen resistance and to rapidly screen drugs that target the resistance mechanism(s), we have previously established several in vitro breast cancer models that have acquired resistance to anti-hormones. Such cells commonly develop an ability to proliferate after approximately 3 months of exposure to 4-hydroxytamoxifen or fulvestrant, despite an initial endocrine-responsive (i.e. growth-suppressive) phase. The current paper explores the role that growth factor signalling plays in the transition of oestrogen receptor-positive endocrine-responsive breast cancer cells to anti-oestrogen resistance or insensitivity and how we might, in the future, most effectively use anti-growth factor therapies to treat or delay endocrine-resistant states.


Assuntos
Neoplasias da Mama/tratamento farmacológico , Antagonistas de Estrogênios/uso terapêutico , Inibidores do Crescimento/uso terapêutico , Moduladores Seletivos de Receptor Estrogênico/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Quimioterapia Combinada , Feminino , Substâncias de Crescimento/metabolismo , Humanos , Fosforilação , Receptores de Superfície Celular/efeitos dos fármacos , Receptores de Superfície Celular/metabolismo , Transdução de Sinais/efeitos dos fármacos
16.
J Lipid Res ; 46(10): 2192-201, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16061953

RESUMO

Halogen-substituted iminosulfuranes are transdermal penetration enhancers (TPEs) in permeation studies using hairless mouse or human cadaver skin. The interaction of N--(4--R-benzoyl)-S,S-dimethyliminosulfuranes 1--4, where R=H, Cl, Br, and I, with l-alpha-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) has been studied using differential scanning calorimetry, isothermal titration calorimetry, nuclear Overhauser effect spectroscopy (NOESY), and NMR spectroscopy, and by calculation of the iminosulfurane polarizabilities in order to elucidate the molecular basis of the TPE activity. The active compounds reduce the melting temperature of the gel-to-liquid-crystal phase transition and induce multiple components in the transition excess heat capacity profile. The partitioning of the bromo derivative 3, the most active compound, into DMPC is unique in that 3 may be trapped in the bilayer, affording an enhanced residence time and a reason for its high TPE activity. The entropy decrease associated with the transfer of 3 to the bilayer is much lower than that for the other compounds, indicating that 3 occupies or induces sites that afford it considerable local motional freedom. Correlations between the iminosulfurane TPE activities, the partition coefficients, and NOESY crosspeak volume were observed. Molecular polarizabilities are not consistent with a TPE mode of action involving interaction of these agents with protein side chains.


Assuntos
Dimetil Sulfóxido/análogos & derivados , Dimetil Sulfóxido/farmacologia , Hidrocortisona/farmacocinética , Iminas/farmacologia , Absorção Cutânea/efeitos dos fármacos , Sulfetos/farmacologia , Animais , Calorimetria , Varredura Diferencial de Calorimetria , Dimetil Sulfóxido/química , Dimiristoilfosfatidilcolina/química , Espectroscopia de Ressonância de Spin Eletrônica , Iminas/química , Bicamadas Lipídicas/química , Camundongos , Camundongos Pelados , Ressonância Magnética Nuclear Biomolecular , Sulfetos/química , Termodinâmica
17.
Endocrinology ; 146(11): 4609-18, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16037379

RESUMO

There is considerable evidence that the epidermal growth factor receptor (EGFR) and IGF-I receptor (IGF-IR) cross-talk in breast cancer cells. In the present study, we have examined whether EGFR/IGF-IR cross-talk exists in EGFR-positive tamoxifen-resistant variants of MCF-7 (Tam-R) and T47D (T47D-R) breast cancer cell lines. Although Tam-R cells expressed reduced IGF-IR protein levels compared with their wild-type MCF-7 counterparts, phosphorylated IGF-IR protein levels were equivalent in the two cell lines under basal growth conditions, possibly as a consequence of increased IGF-II expression in Tam-R cells. IGF-II activated both IGF-IR and EGFR in Tam-R cells, whereas only activation of IGF-IR was observed in wild-type cells. In contrast, epidermal growth factor rapidly induced EGFR, but not IGF-IR, phosphorylation in Tam-R cells. IGF-II promoted direct association of c-SRC with IGF-IR, phosphorylated c-SRC, and increased EGFR phosphorylation at tyrosine 845, a c-SRC-dependent phosphorylation site. Pretreatment with either AG1024 (IGF-IR-specific inhibitor) or an IGF-II neutralizing antibody inhibited basal IGF-IR, c-SRC, and EGFR phosphorylation, and AG1024 significantly reduced Tam-R basal cell growth. The c-SRC inhibitor SU6656 also inhibited growth, reduced basal and IGF-II-induced c-SRC and EGFR phosphorylation, and blocked EGFR activation by TGFalpha. Similarly, in T47D-R cells, AG1024 and SU6656 inhibited basal and IGF-II-induced phosphorylation of c-SRC and EGFR, and SU6656 reduced TGFalpha-induced EGFR activity. These results suggest the existence of a unidirectional IGF-IR/EGFR cross-talk mechanism whereby IGF-II, acting through the IGF-IR, regulates basal and ligand-activated EGFR signaling and cell proliferation in a c-SRC-dependent manner in Tam-R cells. This cross-talk between IGF-IR and EGFR is not unique to Tam-R cells because this mechanism is also active in a tamoxifen-resistant T47D-R cell line.


Assuntos
Antineoplásicos Hormonais/farmacologia , Neoplasias da Mama/fisiopatologia , Resistencia a Medicamentos Antineoplásicos , Receptores ErbB/metabolismo , Receptor IGF Tipo 1/metabolismo , Transdução de Sinais , Tamoxifeno/farmacologia , Linhagem Celular Tumoral , Receptores ErbB/antagonistas & inibidores , Receptores ErbB/efeitos dos fármacos , Feminino , Humanos , Fator de Crescimento Insulin-Like II/farmacologia , Fosforilação/efeitos dos fármacos , Proteínas Proto-Oncogênicas pp60(c-src)/metabolismo , Receptor Cross-Talk , Receptor IGF Tipo 1/antagonistas & inibidores , Fator de Crescimento Transformador alfa/farmacologia
18.
J Steroid Biochem Mol Biol ; 93(2-5): 257-62, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15860268

RESUMO

Recent evidence demonstrates that growth factor networks are highly interactive with the estrogen receptor (ER) in the control of breast cancer growth and development. As such, tumor responses to anti-hormones are likely to be a composite of the ER and growth factor inhibitory activity of these agents, with alterations/aberrations in growth factor signalling providing a mechanism for the development of anti-hormone resistance. In this light, the current article focuses on illustrating the relationship between growth factor signalling and anti-hormone failure in our in-house tumor models of breast cancer and describes how we are now beginning to successfully target their actions to improve the effects of anti-hormonal drugs and to block aggressive disease progression.


Assuntos
Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Substâncias de Crescimento/metabolismo , Resistencia a Medicamentos Antineoplásicos , Quimioterapia Combinada , Receptores ErbB/metabolismo , Feminino , Antagonistas de Hormônios/uso terapêutico , Humanos , Invasividade Neoplásica , Neoplasias Hormônio-Dependentes/tratamento farmacológico , Neoplasias Hormônio-Dependentes/metabolismo , Receptores de Estrogênio/metabolismo , Transdução de Sinais , Tamoxifeno/uso terapêutico , Falha de Tratamento
19.
Endocr Relat Cancer ; 11(4): 793-814, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15613453

RESUMO

De novo and acquired resistance to the anti-tumour drug gefitinib (ZD1839; Iressa), a specific epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) has been reported. We have determined whether signalling through the IGF-I receptor (IGF-1R) pathway plays a role in the gefitinib-acquired resistance phenotype. Continuous exposure of EGFR-positive MCF-7-derived tamoxifen resistant breast cancer cells (TAM-R) to 1 microM gefitinib resulted in a sustained growth inhibition (90%) for 4 months before the surviving cells resumed proliferation. A stable gefitinib-resistant subline (TAM/TKI-R) was established after a further 2 months and this showed no detectable basal phosphorylated EGFR activity. Compared with the parental TAM-R cells, the TAM/ TKI-R cells demonstrated (a) elevated levels of activated IGF-1R, AKT and protein kinase C (PKC)delta, (b) an increased sensitivity to growth inhibition by the IGF-1R TKI AG1024 and (c) an increased migratory capacity that was reduced by AG1024 treatment. Similarly, the EGFR-positive androgen-independent human prostate cancer cell line DU145 was also continuously challenged with 1 microM gefitinib and, although substantial growth inhibition (60%) was seen initially, a gefitinib-resistant variant (DU145/TKI-R) developed after 3 months. Like their breast cancer counterparts, the DU145/TKI-R cells showed increases in the levels of components of the IGF-1R signalling pathway and an elevated sensitivity to growth inhibition by AG1024 compared with the parent DU145 cell line. Additionally, DU145/TKI-R cell migration was also decreased by this inhibitor. We have therefore concluded that in breast and prostate cancer cells acquired resistance to gefitinib is associated with increased signalling via the IGF-1R pathway, which also plays a role in the invasive capacity of the gefitinib-resistant phenotype.


Assuntos
Antineoplásicos/farmacologia , Resistencia a Medicamentos Antineoplásicos , Quinazolinas/farmacologia , Receptor IGF Tipo 1/metabolismo , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , DNA Complementar/metabolismo , Receptores ErbB/antagonistas & inibidores , Receptores ErbB/genética , Receptores ErbB/metabolismo , Gefitinibe , Regulação Neoplásica da Expressão Gênica , Substâncias de Crescimento/genética , Substâncias de Crescimento/metabolismo , Substâncias de Crescimento/farmacologia , Humanos , Receptor IGF Tipo 1/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais
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