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1.
J Environ Manage ; 327: 116949, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36509015

RESUMO

This study investigates the time-varying causal relationship between geopolitical risk and green finance during the period of 1 March 2012-February 16, 2022. By using the novel time-varying causality testing framework, our findings shed light on the nexus between geopolitical risk and green finance in informing environmental management decisions. First, we find that time heterogeneity does exist in the causal relations between geopolitical risk and green finance. Second, geopolitical risk has a more prolonged impact on the volatility of green bonds and renewable energy than the return. Yet, geopolitical risk tends to influence the return of clean energy more persistently than volatility. Third, we observe that geopolitical risk has a more sustained impact on the return and volatility of renewable energy than clean energy. This might be due to the distinct nature of the production of clean energy and renewable energy, thereby providing implications for effective environmental management. Lastly, this paper demonstrates that the impact of geopolitical risk on the return of European clean energy has diminished since the onset of 2015. The volatility of the European clean energy sector is not affected by global geopolitical risk, underscoring the necessity of promoting the development of this sector to reduce the dependence on fossil fuels and enhance energy independence.


Assuntos
Conservação dos Recursos Naturais , Combustíveis Fósseis , Energia Renovável , Desenvolvimento Econômico , Dióxido de Carbono
2.
Atl Econ J ; 50(1-2): 37-51, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35702272

RESUMO

This paper analyses, for the first time, potential convergence patterns of hotel revenues across provinces in China. Through the club clustering methodology, the analysis uses a unique dataset of all hotels across all Chinese provinces. The findings document that these hotel revenues follow a diverging pattern on a national level, while a converging pattern is identified across certain provinces, thus forming specific clubs. When the analysis is extended to identify potential drivers for such diverging or converging behavior, the new results illustrate the role of productivity trends, management strategies and tax policies as those factors that drive such patterns. The results could be of substantial value, primarily for tourism policymakers to further improve the current framework of the Chinese hotel industry to introduce practices and policies that will allow the industry to catch up with the global market. Supplementary Information: The online version contains supplementary material available at 10.1007/s11293-022-09745-6.

3.
J Environ Manage ; 298: 113403, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34365183

RESUMO

Our paper proposes a novel measure of global energy market uncertainty and studies its impact on oil prices. The current literature primarily relies on a single or small number of observable variables, or general macroeconomic uncertainty (JLN) and economic policy uncertainty (EPU) indices to reflect energy market uncertainty. Using a Factor Augmented Vector Autoregression model (FAVAR), we construct time-varying global energy market uncertainty in a data-rich environment. Our estimates show variations from JLN and EPU proxies. The results reveal that real oil prices respond strongly to our proposed aggregate energy market uncertainty shocks. We also find heterogeneous responses to different types and magnitudes of uncertainty shocks. The real price of oil is affected the most under unexpected strong demand for alternative energy sources scenario.


Assuntos
Petróleo , Incerteza
4.
Cancer Cell ; 13(2): 153-66, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18242515

RESUMO

This study characterized cancer stem cells (CSCs) in hepatocellular carcinoma (HCC) cell lines, tumor specimens, and blood samples. The CD90+ cells, but not the CD90(-) cells, from HCC cell lines displayed tumorigenic capacity. All the tumor specimens and 91.6% of blood samples from liver cancer patients bore the CD45(-)CD90+ population, which could generate tumor nodules in immunodeficient mice. The CD90+CD44+ cells demonstrated a more aggressive phenotype than the CD90+CD44(-) counterpart and formed metastatic lesions in the lung of immunodeficient mice. CD44 blockade prevented the formation of local and metastatic tumor nodules by the CD90+ cells. Differential gene expression profiles were identified in the CD45(-)CD90+ and CD45(-)CD90(-) cells isolated from tissue and blood samples from liver cancer patients and controls.


Assuntos
Neoplasias Hepáticas/patologia , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Antígenos Thy-1/metabolismo , Animais , Apoptose , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Separação Celular , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Receptores de Hialuronatos/metabolismo , Antígenos Comuns de Leucócito/metabolismo , Neoplasias Hepáticas/genética , Masculino , Camundongos , Camundongos Nus , Transplante de Neoplasias , Reprodutibilidade dos Testes , Reação em Cadeia da Polimerase Via Transcriptase Reversa
5.
Financ Innov ; 9(1): 30, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36687788

RESUMO

Overconfidence behavior, one form of positive illusion, has drawn considerable attention throughout history because it is viewed as the main reason for many crises. Investors' overconfidence, which can be observed as overtrading following positive returns, may lead to inefficiencies in stock markets. To the best of our knowledge, this is the first study to examine the presence of investor overconfidence by employing an artificial intelligence technique and a nonlinear approach to impulse responses to analyze the impact of different return regimes on the overconfidence attitude. We examine whether investors in an emerging stock market (Borsa Istanbul) exhibit overconfidence behavior using a feed-forward, neural network, nonlinear Granger causality test and nonlinear impulse-response functions based on local projections. These are the first applications in the relevant literature due to the novelty of these models in forecasting high-dimensional, multivariate time series. The results obtained from distinguishing between the different market regimes to analyze the responses of trading volume to return shocks contradict those in the literature, which is the key contribution of the study. The empirical findings imply that overconfidence behavior exhibits asymmetries in different return regimes and is persistent during the 20-day forecasting horizon. Overconfidence is more persistent in the low- than in the high-return regime. In the negative interest-rate period, a high-return regime induces overconfidence behavior, whereas in the positive interest-rate period, a low-return regime induces overconfidence behavior. Based on the empirical findings, investors should be aware that portfolio gains may result in losses depending on aggressive and excessive trading strategies, particularly in low-return regimes.

6.
Front Public Health ; 10: 854771, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36111195

RESUMO

The COVID-19 pandemic has affected various dimensions of the economies and societies. At this juncture, this paper examines the effects of pandemics-related uncertainty on fertility in the panel dataset of 126 countries from 1996 to 2019. For this purpose, the World Pandemics Uncertainty Indices are used to measure the pandemics-related uncertainty. The novel empirical evidence is that pandemics-related uncertainty decreases fertility rates. These results are robust to estimate different models and include various controls. We also try to explain why the rise in uncertainty during the COVID-19 pandemic has resulted in the fertility decline.


Assuntos
COVID-19 , Pandemias , Coeficiente de Natalidade , COVID-19/epidemiologia , Fertilidade , Humanos , Incerteza
7.
Front Public Health ; 10: 872561, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35602128

RESUMO

Vaccines are essential to create a more resilient economic growth model. Ending the COVID-19 pandemic requires a more coordinated, effective, and equitable distribution of vaccines across the countries. Therefore, governments are in a race to increase the vaccination rates of the population. Given this backdrop, this paper focuses on the daily vaccinations per million data from March 1, 2021, to October 15, 2021, in 37 Organization for Economic Co-operation and Development (OECD) countries and examines the stochastic properties of the vaccination rates. We adopt the club convergence econometric methodology to investigate the club convergence paths of COVID-19 vaccination rates in OECD regions. The results indicate a significant convergence of the vaccination rates in seven clubs across 30 OECD countries. Moreover, there are seven OECD countries demonstrate non-convergent characteristics, which raises questions about ineffective vaccine balance. In addition, the paper also discusses the potential implications for the post-COVID-19 era.


Assuntos
COVID-19 , Vacinas , COVID-19/epidemiologia , COVID-19/prevenção & controle , Vacinas contra COVID-19 , Humanos , Organização para a Cooperação e Desenvolvimento Econômico , Pandemias , Vacinação
8.
Front Public Health ; 9: 651051, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33777889

RESUMO

This paper analyses the effects of the Chinese Economic Policy Uncertainty (CEPU) index on the daily returns of Bitcoin for the period from December 31, 2019 to May 20, 2020. Utilizing the Ordinary Least Squares (OLS) and the Generalized Quantile Regression (GQR) estimation techniques, the paper illustrates that the current CEPU has a positive impact on the returns of Bitcoin. However, the positive impact is statistically significant only at the higher quantiles of the current CEPU. It is concluded that Bitcoin can be used in hedging against policy uncertainties in China since significant rises in uncertainty leads to a higher return in Bitcoin. JEL Codes: G32; G15; C22.


Assuntos
COVID-19/economia , Comércio/economia , Comércio/estatística & dados numéricos , Economia , COVID-19/epidemiologia , China/epidemiologia , Humanos , Modelos Econômicos , Análise de Regressão , SARS-CoV-2
9.
Clin Cancer Res ; 15(10): 3462-71, 2009 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-19447872

RESUMO

PURPOSE: The goals of the present study were to investigate the mechanism of hypoxia-mediated chemoresistance in liver cancer cells and tumorigenic hepatic progenitor (oval) cells and to determine whether disrupting an Akt/hypoxia-inducible factor-1alpha (HIF-1alpha)/platelet-derived growth factor (PDGF)-BB autocrine loop can enhance chemotherapeutic efficacy in hypoxia. EXPERIMENTAL DESIGN: Five hepatocellular carcinoma (HCC) cell lines and two hepatic progenitor cell lines were treated in vitro with cisplatin under both normoxic and hypoxic conditions. To generate ischemic hypoxia for tumor cells in vivo, hepatic artery ligation was applied to an orthotopic HCC model. Cisplatin and YC1, which is a HIF-1alpha inhibitor, were administered by portal vein and intratumoral injections, respectively. RESULTS: Cell viability was higher under hypoxic than normoxic conditions. HIF-1alpha and Akt were up-regulated under hypoxic conditions, forming an autocrine signaling loop with PDGF-BB. Akt/HIF-1alpha/PDGF-BB signaling regulated Akt to confer cisplatin resistance to HCC cell lines in vitro. This autocrine signaling loop also contributed to chemoresistance in the tumorigenic hepatic progenitor cell line PIL2 under hypoxic conditions but not in the nontumorigenic cell line PIL4. In an orthotopic HCC model, combining blockade of HIF-1alpha activity with ischemic hypoxia significantly enhanced the efficacy of chemotherapy, leading to suppression of tumor growth and prolongation of animal survival. CONCLUSION: Blockade of Akt/HIF-1alpha/PDGF-BB autocrine signaling could enhance the chemosensitivity of liver cancer cells and tumorigenic hepatic progenitor cells under hypoxic conditions and thus provide an effective therapeutic strategy for HCC.


Assuntos
Antineoplásicos/farmacologia , Resistencia a Medicamentos Antineoplásicos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Proteína Oncogênica v-akt/metabolismo , Fator de Crescimento Derivado de Plaquetas/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Becaplermina , Western Blotting , Hipóxia Celular , Linhagem Celular , Linhagem Celular Tumoral , Cisplatino/farmacologia , Citometria de Fluxo , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas Experimentais/tratamento farmacológico , Neoplasias Hepáticas Experimentais/metabolismo , Neoplasias Hepáticas Experimentais/patologia , Proteína Oncogênica v-akt/genética , Oxigênio/metabolismo , Oxigênio/farmacologia , Fator de Crescimento Derivado de Plaquetas/genética , Proteínas Proto-Oncogênicas c-sis , Interferência de RNA , Ratos , Ratos Endogâmicos BUF , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células-Tronco/citologia , Células-Tronco/efeitos dos fármacos , Células-Tronco/metabolismo , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto
10.
J Appl Stat ; 47(6): 1109-1127, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-35706914

RESUMO

We examine the impact of the Indian cricket team's performance in one-day international cricket matches on return, realized volatility and jumps of the Indian stock market, based on intraday data covering the period of 30th October, 2006 to 31st March, 2017. Using a nonparametric causality-in-quantiles test, we were able to detect evidence of predictability from wins or losses for primarily volatility and jumps, especially over the lower-quantiles of the conditional distributions, with losses having stronger predictability than wins. However, the impact on the stock return is weak and restricted towards the upper end of the conditional distribution.

11.
Environ Sci Pollut Res Int ; 27(8): 8548-8556, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31907817

RESUMO

This paper analyzes the role of international cooperation on CO2 emissions growth in 36 OECD economies over the period 1970-2016. The indices of political globalization are the benchmark measure of international cooperation since a higher value of the index of political globalization is an indicator of collaboration in the world. The paper finds that political globalization decreases CO2 emissions growth. The findings remain robust when we consider the sub-indices of political globalization and include various controls. Also, the findings of the panel quantile regressions with the fixed-effects via the method of moments indicate that the effects of per capita income and the initial level of CO2 emissions are higher in more pollutant countries. However, the impact of political globalization on CO2 emissions is stable at different quantiles. The paper also discusses the potential implications for the role of international cooperation on climate change.


Assuntos
Dióxido de Carbono , Desenvolvimento Econômico , Dióxido de Carbono/análise , Renda/estatística & dados numéricos , Cooperação Internacional , Organização para a Cooperação e Desenvolvimento Econômico
12.
Hepatology ; 47(3): 919-28, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18275073

RESUMO

UNLABELLED: Increasing evidence has revealed the importance of cancer stem cells (CSCs) in carcinogenesis. Although liver CSCs have been identified in hepatocellular carcinoma (HCC) cell lines, no data have shown the presence of these cells in human settings. The present study was designed to delineate CSCs serially from HCC cell lines, human liver cancer specimens to blood samples, using CD90 as a potential marker. The number of CD90(+) cells increased with the tumorigenicity of HCC cell lines. CD45(-)CD90(+) cells were detected in all the tumor specimens, but not in the normal, cirrhotic, and parallel nontumorous livers. In addition, CD45(-)CD90(+) cells were detectable in 90% of blood samples from liver cancer patients, but none in normal subjects or patients with cirrhosis. A significant positive correlation between the number of CD45(-)CD90(+) cells in the tumor tissues and the number of CD45(-)CD90(+) cells in the blood samples was identified. CD90(+) cells sorted from cell lines and CD45(-)CD90(+) cells from the tumor tissues and blood samples of liver cancer patients generated tumor nodules in immunodeficient mice. Serial transplantation of CD90(+) cells from tumor xenografts generated tumor nodules in a second and subsequently third batch of immunodeficient mice. Treatment of CD90(+) CSCs with anti-human CD44 antibody induced cell apoptosis in a dose-dependent manner. CONCLUSION: Identification of CD45(-)CD90(+) CSCs in both tumor tissues and circulation suggests that CD45(-)CD90(+) could be used as a marker for human liver cancer and as a target for the diagnosis and therapy of this malignancy.


Assuntos
Carcinoma Hepatocelular/diagnóstico , Neoplasias Hepáticas/diagnóstico , Células Neoplásicas Circulantes/química , Células-Tronco Neoplásicas/química , Antígenos Thy-1/análise , Animais , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Transformação Celular Neoplásica/patologia , Citometria de Fluxo , Humanos , Antígenos Comuns de Leucócito/análise , Neoplasias Hepáticas/patologia , Camundongos , Camundongos SCID , Células Neoplásicas Circulantes/patologia , Células-Tronco Neoplásicas/patologia
13.
Environ Sci Pollut Res Int ; 26(18): 18834-18845, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31065977

RESUMO

This paper investigates the impact of tourism investments on energy efficiency across the transportation and residential sectors of 32 Organization for Economic Co-operation and Development economies. Using annual data from 1995 to 2012, we employ various panel econometric techniques to achieve the study objectives. Given the nature of variables, the paper applies panel autoregressive distributed lag models to estimate the long-run elasticities of energy intensity. The long-run estimates confirm that tourism investments play an essential role in improving energy efficiency across the transportation and residential sectors. Furthermore, the results show that both the foreign direct investment inflows and trade openness also play a considerable role in reducing energy uses across these sectors. Finally, the findings suggest that the tourism investments Granger cause energy efficiency of transportation and residential sectors in the short-run. Given these findings, the paper adds considerable value to the empirical literature and also provides various policy- and practical implications.


Assuntos
Desenvolvimento Econômico , Fontes Geradoras de Energia/economia , Habitação/economia , Investimentos em Saúde , Atividades de Lazer/economia , Meios de Transporte/economia , Internacionalidade , Organização para a Cooperação e Desenvolvimento Econômico
14.
Environ Sci Pollut Res Int ; 26(2): 1455-1463, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30426378

RESUMO

This paper uses the 1990-2010 natural disaster and carbon emission data of G20 countries to examine the impact of natural disasters and climate change on the natural capital component of inclusive wealth. Our study shows that climate change and GDP have no positive impacts on the growth of natural capital. By contrast, trade openness and natural disaster frequency contribute to the accumulation of natural capital in G20 countries. There is an inverted U-shaped relationship between the growth of natural capital and the magnitude of natural disaster. Natural capital growth is not affected very much by small disasters. By contrast, large disasters tend to make the growth of natural capital fall sharply.


Assuntos
Mudança Climática , Conservação dos Recursos Naturais/economia , Países Desenvolvidos , Desenvolvimento Econômico , Desastres Naturais , Humanos , Desenvolvimento Sustentável
15.
J Gene Med ; 10(12): 1315-23, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18816483

RESUMO

BACKGROUND: Genetic manipulation of the allograft is an attractive approach to prevent the graft against chronic deterioration through stable expression of immunomodulatory or protective genes. However, the best strategy for prevention of chronic allograft deterioration remains unclear. METHODS: The efficacies of adeno-associated viral vector-mediated stable expression of indoleamine 2,3-dioxygenase (IDO), cytotoxic T-lymphocyte associated antigen 4 with human immunoglobulin G(1) (CTLA4Ig) or interleukin-10 (IL-10) in the prevention of chronic allograft deterioration were compared in a rat heart transplantation model. RESULTS: Transduction of grafts with IL-10 significantly prolonged allograft survival, whereas transduction of grafts with IDO did not improve graft survival compared to controls. Analysis of long-term survived heart allografts showed that both CTLA4Ig and IL-10 could significantly reduced the T cells and macrophage infiltration. However, stable expression of CTLA4Ig failed to prevent the development of transplant arteriosclerosis. By contrast, IL-10 suppressed the development of transplant arteriosclerosis effectively. The suppressive effects of IL-10 in preventing the development of chronic allograft deterioration were associated with lower transcript levels of transforming tumor growth factor beta 1 and macrophage migration inhibitory factor in the graft. In addition, higher transcript levels of heme oxygenase-1 were found in IL-10-transduced allograft. CONCLUSIONS: Targeting on IL-10 is superior to CTLA4Ig or IDO for the treatment of chronic allograft deterioration.


Assuntos
Sobrevivência de Enxerto , Transplante de Coração , Imunoconjugados/genética , Interleucina-10/genética , Abatacepte , Animais , Células Cultivadas , Vetores Genéticos/genética , Vetores Genéticos/uso terapêutico , Sobrevivência de Enxerto/imunologia , Transplante de Coração/imunologia , Humanos , Imunoconjugados/imunologia , Interleucina-10/imunologia , Masculino , Ratos , Ratos Endogâmicos F344 , Ratos Endogâmicos Lew , Transgenes , Transplante Homólogo
16.
Liver Int ; 28(5): 622-31, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18312290

RESUMO

BACKGROUND/AIM: Hepatic resection is not applicable to a certain proportion of hepatocellular carcinoma patients owing to an insufficient liver function reserve. The present study was designed to investigate the effects of cardiotrophin-1 (CT-1) on improving the function of CCl(4)-induced cirrhotic liver remnant after major hepatectomy. METHODS: CT-1 was administered to rats after hepatectomy according to different protocols. RESULTS: A double-dose CT-1 protocol improved liver function, enlarged the volume of liver remnant, upregulated the expression of von Willebrand factor and increased the number of BrdU(+) or Ki-67(+) hepatocytes. Administration of CT-1 enhanced the expression of nuclear factor-kappaB (P65), vascular endothelial growth factor (VEGF), CyclinD1 and p42/44 in the liver remnant. However, the effects of CT-1 were blocked by a VEGF receptor blocker, PTK787. Although the expression of gp130, a receptor of CT-1, was downregulated in the diseased hepatocytes isolated from the cirrhotic liver, CT-1 could still stimulate the cell proliferation. CT-1 administration enhanced the expression of P65 and VEGF in the diseased hepatocytes, but the augmented P65 and VEGF expression was blocked by PTK787 administration. CONCLUSION: Short-term administration of CT-1 could improve the function of cirrhotic liver remnant and stimulate liver regeneration through promotion of angiogenesis and cell proliferation.


Assuntos
Proliferação de Células/efeitos dos fármacos , Citocinas/uso terapêutico , Cirrose Hepática , Regeneração Hepática/efeitos dos fármacos , Neovascularização Fisiológica/efeitos dos fármacos , Animais , Tetracloreto de Carbono , Citocinas/farmacologia , Hepatectomia , Hepatócitos/efeitos dos fármacos , Cirrose Hepática/induzido quimicamente , Masculino , Ratos , Ratos Endogâmicos BUF , Fator de Transcrição RelA/metabolismo , Regulação para Cima , Fator A de Crescimento do Endotélio Vascular/metabolismo
17.
Environ Sci Pollut Res Int ; 25(14): 14106-14116, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29520551

RESUMO

This paper provides the evidence on the short- and the long-run effects of the export product concentration on the level of CO2 emissions in 19 developed (high-income) economies, spanning the period 1962-2010. To this end, the paper makes use of the nonlinear panel unit root and cointegration tests with multiple endogenous structural breaks. It also considers the mean group estimations, the autoregressive distributed lag model, and the panel quantile regression estimations. The findings illustrate that the environmental Kuznets curve (EKC) hypothesis is valid in the panel dataset of 19 developed economies. In addition, it documents that a higher level of the product concentration of exports leads to lower CO2 emissions. The results from the panel quantile regressions also indicate that the effect of the export product concentration upon the per capita CO2 emissions is relatively high at the higher quantiles.


Assuntos
Dióxido de Carbono/análise , Países Desenvolvidos/economia , Desenvolvimento Econômico/tendências , Modelos Teóricos , Países Desenvolvidos/estatística & dados numéricos , Desenvolvimento Econômico/estatística & dados numéricos , Pesquisa Empírica , Aquecimento Global , Renda
18.
Mol Cancer Ther ; 5(9): 2261-70, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16985060

RESUMO

The present study aimed to investigate the therapeutic efficacy of combining vascular endothelial growth factor (VEGF) receptor blockade using tyrosine kinase inhibitor PTK787 with hypoxia for the treatment of hepatocellular carcinoma (HCC). The in vivo effects of the treatments were determined in a rat orthotopic HCC model, in which hypoxia was generated by hepatic artery ligation (HAL). Compared with HAL alone, PTK787 combined with HAL significantly prolonged the animal survival, reduced the tumor size, induced more tumor tissue necrosis and apoptosis, and down-regulated the expression of von Willebrand factor. The mechanism was explored in vitro using murine HCC and endothelial cell lines, respectively. PTK787 combined with hypoxia decreased the expression of VEGF and VEGF receptors in both cell lines and suppressed the cell viability by induction of cell cycle arrest and promotion of apoptosis. Up-regulation of cleaved form caspase-9 and down-regulation of Bcl-2 and cyclin D1 were detected with the combined treatment. Hypoxia sensitized endothelial cells to the inhibitory effect of PTK787 on forming tubular-like structure. The motility of tumor cells was inhibited by hypoxia and the combined approach, with down-regulation of Rac1, Rho, and phosphorylated Akt expression. However, in the endothelial cells, the combined treatment inhibited the hypoxia-enhanced cell motility, with suppressed Rac1, Rho, and phosphorylated Akt expression. In conclusion, PTK787 combined with hypoxia achieved a better therapeutic efficacy than hypoxia alone through enhancing hypoxia-induced antitumor cell effect and preventing the activation of angiogenic process.


Assuntos
Inibidores da Angiogênese/farmacologia , Neoplasias Hepáticas Experimentais/tratamento farmacológico , Ftalazinas/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Proteínas Tirosina Quinases/antagonistas & inibidores , Piridinas/farmacologia , Animais , Apoptose/efeitos dos fármacos , Hipóxia Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Células Endoteliais/citologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/enzimologia , Células Endoteliais/metabolismo , Neoplasias Hepáticas Experimentais/irrigação sanguínea , Neoplasias Hepáticas Experimentais/enzimologia , Neoplasias Hepáticas Experimentais/patologia , Masculino , Camundongos , Neovascularização Patológica/tratamento farmacológico , Neovascularização Patológica/enzimologia , Neovascularização Patológica/patologia , Ratos , Ratos Endogâmicos BUF , Fator A de Crescimento do Endotélio Vascular/sangue
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