Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 28
Filtrar
1.
QJM ; 113(9): 643-650, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32186731

RESUMO

OBJECTIVE: Air pollution had been reported to be associated with the reproductive health of women. However, the association of particulate matter (PM) and acid gases air pollution with premenstrual syndrome (PMS) warrants investigation. This study investigated the effects of air pollution on PMS risk. POPULATION: We combined data from the Taiwan Air Quality-Monitoring Database and the Longitudinal Health Insurance Database. In total, an observational cohort of 85 078 Taiwanese women not diagnosed as having PMS. METHODS: Air pollutant concentrations were grouped into four levels based on the concentration quartiles of several types of air pollutants. MAIN OUTCOME MEASURES: We then applied univariable and multivariable Cox proportional hazard regression models to assess PMS risk in association with each pollutant type. RESULTS: Women exposed to Q4-level SO2 exhibited a 7.77 times higher PMS risk compared with those to Q1-level SO2 (95% confidence interval [CI] = 6.22-9.71). Women exposed to Q4-level NOx exhibited a 2.86 times higher PMS risk compared with those exposed to Q1-level NOx (95% CI = 2.39-3.43). Women exposed to Q4-level NO exhibited a 3.17 times higher PMS risk compared with women exposed to Q1-level NO (95% CI = 2.68-3.75). Finally, women exposed to Q4-level PM with a ≤2.5-µm diameter (PM2.5) exhibited a 3.41 times higher PMS risk compared with those exposed to Q1-level PM2.5 (95% CI = 2.88-4.04). CONCLUSIONS: High incidences of PMS were noted in women who lived in areas with higher concentrations of SO2, NOx, NO, NO2 and PM2.5.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar/efeitos adversos , Material Particulado/análise , Síndrome Pré-Menstrual/epidemiologia , Adolescente , Adulto , Poluição do Ar/estatística & dados numéricos , Atmosfera/química , Estudos de Coortes , Feminino , Humanos , Concentração de Íons de Hidrogênio , Pessoa de Meia-Idade , Análise Multivariada , Nitratos/análise , Ozônio/análise , Modelos de Riscos Proporcionais , Sulfatos/análise , Taiwan/epidemiologia , Adulto Jovem
2.
Oncogenesis ; 6(5): e335, 2017 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-28504690

RESUMO

Despite advances in early diagnosis and the development of molecularly targeted therapy, curative treatment of colon cancer once it has metastasized is yet to be accomplished. This is closely associated with deregulated CRC cell proliferation and resistance to apoptosis. Here we reveal that upregulation of microRNA-645 (miR-645) through DNA copy number gain is responsible for enhanced proliferation and resistance to apoptosis in colon cancer. MiR-645 was upregulated in most colon cancer tissues related to adjacent normal mucosa. This appeared to be associated with amplification of a section of chromosome 20q13.13, where miR-645 is located. Inhibition of miR-645 reduced proliferation and enhanced sensitivity to apoptosis triggered by the chemotherapeutic drugs 5-fluorouracil and cisplatin in CRC cells, and retarded colon cancer xenograft growth. Conversely, overexpression of miR-645 in normal colon epithelial cells enhanced proliferation and triggered anchorage-independent cell growth. Although SRY-related HMG-box 30 (SOX30) was identified as a miR-645 target, its expression was only partially affected by miR-645, suggesting that miR-645 is a fine-tuning mechanism of SOX30 expression. Moreover, overexpression of SOX30 only moderately inhibited promotion of CRC cell proliferation by miR-645, indicating that miR-645 may have more targets that contribute to its pro-proliferation effect in colon cancer. Together, this study reveals that miR-645 can regulate oncogenesis in colon cancer with SOX30 being one of its targets.

4.
Ann Oncol ; 27(3): 409-16, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26681673

RESUMO

Evasion of immune system is a hallmark of cancer, which enables cancer cells to escape the attack from immune cells. Cancer cells can express many immune inhibitory signalling proteins to cause immune cell dysfunction and apoptosis. One of these inhibitory molecules is programmed death-ligand-1 (PD-L1), which binds to programmed death-1 (PD-1) expressed on T-cells, B-cells, dendritic cells and natural killer T-cells to suppress anti-cancer immunity. Therefore, anti-PD-L1 and anti-PD-1 antibodies have been used for the treatment of cancer, showing promising outcomes. However, only a proportion of patients respond to the treatments. Further understanding of the regulation of PD-L1 expression could be helpful for the improvement of anti-PD-L1 and anti-PD-1 treatments. Studies have shown that PD-L1 expression is regulated by signalling pathways, transcriptional factors and epigenetic factors. In this review, we summarise the recent progress of the regulation of PD-L1 expression in cancer cells and propose a regulatory model for unified explanation. Both PI3K and MAPK pathways are involved in PD-L1 regulation but the downstream molecules that control PD-L1 and cell proliferation may differ. Transcriptional factors hypoxia-inducible factor-1α and signal transducer and activation of transcription-3 act on the promoter of PD-L1 to regulate its expression. In addition, microRNAs including miR-570, miR-513, miR-197, miR-34a and miR-200 negatively regulate PD-L1. Clinically, it could increase treatment efficacy of targeted therapy by choosing those molecules that control both PD-L1 expression and cell proliferation.


Assuntos
Antígeno B7-H1/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Neoplasias/imunologia , Fosfatidilinositol 3-Quinases/metabolismo , Receptor de Morte Celular Programada 1/metabolismo , Transdução de Sinais/imunologia , Evasão Tumoral/imunologia , Linfócitos B/imunologia , Antígeno B7-H1/genética , Antígeno B7-H1/imunologia , Biomarcadores Tumorais , Proliferação de Células , Células Dendríticas/imunologia , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , MicroRNAs/genética , NF-kappa B/metabolismo , Células T Matadoras Naturais/imunologia , Neoplasias/metabolismo , Receptor de Morte Celular Programada 1/imunologia , Regiões Promotoras Genéticas/genética , Ligação Proteica/imunologia , Fator de Transcrição STAT3/metabolismo , Linfócitos T/imunologia
5.
Oncogene ; 35(23): 3049-61, 2016 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-26411369

RESUMO

Inositol polyphosphate 4-phosphatase type II (INPP4B) negatively regulates phosphatidylinositol 3-kinase signaling and is a tumor suppressor in some types of cancers. However, we have found that it is frequently upregulated in human colon cancer cells. Here we show that silencing of INPP4B blocks activation of Akt and serum- and glucocorticoid-regulated kinase 3 (SGK3), inhibits colon cancer cell proliferation and retards colon cancer xenograft growth. Conversely, overexpression of INPP4B increases proliferation and triggers anchorage-independent growth of normal colon epithelial cells. Moreover, we demonstrate that the effect of INPP4B on Akt and SGK3 is associated with inactivation of phosphate and tensin homolog through its protein phosphatase activity and that the increase in INPP4B is due to Ets-1-mediated transcriptional upregulation in colon cancer cells. Collectively, these results suggest that INPP4B may function as an oncogenic driver in colon cancer, with potential implications for targeting INPP4B as a novel approach to treat this disease.


Assuntos
Neoplasias do Colo/genética , Monoéster Fosfórico Hidrolases/genética , Linhagem Celular Tumoral , Proliferação de Células/genética , Neoplasias do Colo/metabolismo , Neoplasias do Colo/patologia , Humanos , Imuno-Histoquímica , Monoéster Fosfórico Hidrolases/metabolismo
6.
Oncogene ; 33(20): 2577-88, 2014 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-23770856

RESUMO

Increased global protein synthesis and selective translation of mRNAs encoding proteins contributing to malignancy is common in cancer cells. This is often associated with elevated expression of eukaryotic translation initiation factor 4 (eIF4E), the rate-limiting factor of cap-dependent translation initiation. We report here that in human melanoma downregulation of miR-768-3p as a result of activation of the mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway has an important role in the upregulation of eIF4E and enhancement in protein synthesis. Melanoma cells displayed increased nascent protein production and elevated eIF4E expression, which was associated with the downregulation of miR-768-3p that was predicted to target the 3'-untranslated region of the eIF4E mRNA. Overexpression of miR-768-3p led to the downregulation of the endogenous eIF4E protein, reduction in nascent protein synthesis and inhibition of cell survival and proliferation. These effects were efficiently reversed when eIF4E was co-overexpressed in melanoma cells. On the other hand, introduction of anti-miR-768-3p into melanocytes upregulated endogenous eIF4E protein expression and increased global protein synthesis. Downregulation of miR-768-3p appeared to be mediated by activation of the MEK/ERK pathway, in that treatment of BRAF(V600E) melanoma cells with the mutant BRAF inhibitor PLX4720 or exposure of either BRAF(V600E) or wild-type BRAF melanoma cells to the MEK inhibitor U0126 resulted in the upregulation of miR-768-3p and inhibition of nascent protein synthesis. This inhibition was partially blocked in cells cointroduced with anti-miR-768-3p. Significantly, miR-768-3p was similarly downregulated, which was inversely associated with the expression levels of eIF4E in fresh melanoma isolates. Taken together, these results identify downregulation of miR-768-3p and subsequent upregulation of eIF4E as an important mechanism in addition to phosphorylation of eIF4E responsible for MEK/ERK-mediated enhancement of protein synthesis in melanoma.


Assuntos
Sistema de Sinalização das MAP Quinases , Melanoma/genética , MicroRNAs/genética , Biossíntese de Proteínas , RNA Mensageiro/genética , Transdução de Sinais , Linhagem Celular Tumoral , Regulação para Baixo , Fator de Iniciação 4E em Eucariotos/metabolismo , Humanos , Melanoma/metabolismo , Melanoma/patologia , Regulação para Cima
7.
Curr Med Chem ; 21(10): 1255-67, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24304284

RESUMO

Epidemiological evidence has linked the development and progression of several cancers including melanoma with obesity. However, whether obesity impinges on responses of cancer cells to treatment remains less understood. Here we report that human adipocytes contribute to resistance of melanoma cells to various therapeutic agents. Exposure to media from adipocyte cultures (adipocyte media) increased cell proliferation and reduced sensitivity of melanoma cells to apoptosis induced by diverse chemotherapeutic drugs, including the DNA-damaging drug cisplatin, the microtubuletargeting agent docetaxel, and the histone deacetylase inhibitor SAHA. This was associated with increased activation of PI3K/Akt and MEK/ERK signaling, and was attenuated by a PI3K or MEK inhibitor. The effect of adipocyte media on melanoma cells was, at least in part, due to the interaction between the adipokine leptin and its long form receptor OB-Rb, in that immunodepletion of leptin in adipocyte media or siRNA knockdown of OB-Rb in melanoma cells reversed the increase in Akt and ERK activation, enhancement in cell proliferation, and importantly, protection of melanoma cells against the drugs. In support, recombinant leptin partially recapitulated the effect of adipocyte media on melanoma cells. Of note, OB-Rb was increased on the surface of melanoma cells compared to melanocytes, whereas leptin short form receptors appeared to be suppressed post-transcriptionally, suggesting that OB-Rb was selectively upregulated in melanoma cells. Collectively, these results indicate that adipocytes contribute to the resistance of melanoma cells to chemotherapeutic drugs and agents targeting the PI3K/Akt and MEK/ERK pathways, and suggest that inhibition of the leptin/ OB-Rb system may be useful to improve the efficacy of multiple therapeutic approaches in the treatment of melanoma.


Assuntos
Adipócitos/metabolismo , Antineoplásicos/farmacologia , Resistencia a Medicamentos Antineoplásicos/genética , Regulação Neoplásica da Expressão Gênica , Queratinócitos/efeitos dos fármacos , Adipócitos/citologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cisplatino/farmacologia , Meios de Cultivo Condicionados/farmacologia , Docetaxel , Inibidores de Histona Desacetilases/farmacologia , Humanos , Queratinócitos/metabolismo , Queratinócitos/patologia , Leptina/deficiência , Leptina/genética , MAP Quinase Quinase Quinases/antagonistas & inibidores , MAP Quinase Quinase Quinases/genética , MAP Quinase Quinase Quinases/metabolismo , Terapia de Alvo Molecular , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Inibidores de Fosfoinositídeo-3 Quinase , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Receptores para Leptina/antagonistas & inibidores , Receptores para Leptina/genética , Receptores para Leptina/metabolismo , Transdução de Sinais , Taxoides/farmacologia
8.
Oncogene ; 33(39): 4756-66, 2014 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-24121273

RESUMO

Akt is constitutively activated in up to 70% of human melanomas and has an important role in the pathogenesis of the disease. However, little is known about protein phosphatases that dephosphorylate and thereby inactivate it in melanoma cells. Here we report that suppression of pleckstrin homology domain and leucine-rich repeat Ser/Thr protein phosphatase 1 (PHLPP1) by DNA methylation promotes Akt activation and has an oncogenic role in melanoma. While it is commonly downregulated, overexpression of PHLPP1 reduces Akt activation and inhibits melanoma cell proliferation in vitro, and retards melanoma growth in a xenograft model. In contrast, knockdown of PHLPP1 increases Akt activation, enhances melanoma cell and melanocyte proliferation, and results in anchorage-independent growth of melanocytes. Suppression of PHLPP1 involves blockade of binding of the transcription factor Sp1 to the PHLPP1 promoter. Collectively, these results suggest that suppression of PHLPP1 by DNA methylation contributes to melanoma development and progression.


Assuntos
Regulação Neoplásica da Expressão Gênica , Inativação Gênica , Melanoma/genética , Proteínas Nucleares/genética , Fosfoproteínas Fosfatases/genética , Animais , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular , Metilação de DNA , Regulação para Baixo , Ativação Enzimática , Humanos , Masculino , Melanoma/metabolismo , Melanoma/patologia , Camundongos , Camundongos Nus , Proteínas Nucleares/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Fosfoproteínas Fosfatases/metabolismo , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas c-akt/metabolismo , Fator de Transcrição Sp1/metabolismo , Carga Tumoral
9.
Cell Death Dis ; 4: e914, 2013 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-24201813

RESUMO

An activating BRAF (V600E) kinase mutation occurs in approximately half of melanomas. Recent clinical studies have demonstrated that vemurafenib (PLX4032) and dabrafenib, potent and selective inhibitors of mutant v-raf murine sarcoma viral oncogene homolog B1 (BRAF), exhibit remarkable activities in patients with V600 BRAF mutant melanomas. However, acquired drug resistance invariably develops after the initial treatment. Identification of acquired resistance mechanisms may inform the development of new therapies that elicit long-term responses of melanomas to BRAF inhibitors. Here we report that increased expression of AEBP1 (adipocyte enhancer-binding protein 1) confers acquired resistance to BRAF inhibition in melanoma. AEBP1 is shown to be highly upregulated in PLX4032-resistant melanoma cells because of the hyperactivation of the PI3K/Akt-cAMP response element-binding protein (CREB) signaling pathway. This upregulates AEBP1 expression and thus leads to the activation of NF-κB via accelerating IκBa degradation. In addition, inhibition of the PI3K/Akt-CREB-AEBP1-NF-κB pathway greatly reverses the PLX4032-resistant phenotype of melanoma cells. Furthermore, increased expression of AEBP1 is validated in post-treatment tumors in patients with acquired resistance to BRAF inhibitor. Therefore, these results reveal a novel PI3K/Akt-CREB-AEBP1-NF-κB pathway whose activation contributes to acquired resistance to BRAF inhibition, and suggest that this pathway, particularly AEBP1, may represent a novel therapeutic target for treating BRAF inhibitor-resistant melanoma.


Assuntos
Carboxipeptidases/metabolismo , Melanoma/metabolismo , Proteínas Proto-Oncogênicas B-raf/metabolismo , Proteínas Repressoras/metabolismo , Animais , Proteína de Ligação a CREB/genética , Proteína de Ligação a CREB/metabolismo , Carboxipeptidases/genética , Linhagem Celular Tumoral , Imunoprecipitação da Cromatina , Resistencia a Medicamentos Antineoplásicos/genética , Humanos , Técnicas In Vitro , Indóis/farmacologia , Lentivirus/genética , Melanoma/tratamento farmacológico , Melanoma/genética , Camundongos , Camundongos Nus , NF-kappa B/metabolismo , Proteínas Proto-Oncogênicas B-raf/genética , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Interferente Pequeno/genética , Proteínas Repressoras/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Sulfonamidas/farmacologia , Vemurafenib
10.
Cell Death Dis ; 4: e655, 2013 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-23744355

RESUMO

Past studies have shown that histone deacetylase (HDAC) and mutant BRAF (v-Raf murine sarcoma viral oncogene homolog B1) inhibitors synergistically kill melanoma cells with activating mutations in BRAF. However, the mechanism(s) involved remains less understood. Here, we report that combinations of HDAC and BRAF inhibitors kill BRAF(V600E) melanoma cells by induction of necrosis. Cotreatment with the HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) or panobinostat (LBH589) and the BRAF inhibitor PLX4720 activated the caspase cascade, but caspases appeared dispensable for killing, in that inhibition of caspases did not invariably block induction of cell death. The majority of dying cells acquired propidium iodide positivity instantly when they became positive for Annexin V, suggesting induction of necrosis. This was supported by caspase-independent release of high-mobility group protein B1, and further consolidated by rupture of the plasma membrane and loss of nuclear and cytoplasmic contents, as manifested by transmission electron microscopic analysis. Of note, neither the necrosis inhibitor necrostatin-1 nor the small interference RNA (siRNA) knockdown of receptor-interacting protein kinase 3 (RIPK3) inhibited cell death, suggesting that RIPK1 and RIPK3 do not contribute to induction of necrosis by combinations of HDAC and BRAF inhibitors in BRAF(V600E) melanoma cells. Significantly, SAHA and the clinically available BRAF inhibitor vemurafenib cooperatively inhibited BRAF(V600E) melanoma xenograft growth in a mouse model even when caspase-3 was inhibited. Taken together, these results indicate that cotreatment with HDAC and BRAF inhibitors can bypass canonical cell death pathways to kill melanoma cells, which may be of therapeutic advantage in the treatment of melanoma.


Assuntos
Antineoplásicos/farmacologia , Inibidores de Histona Desacetilases/farmacologia , Melanoma/tratamento farmacológico , Proteínas Proto-Oncogênicas B-raf/antagonistas & inibidores , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sinergismo Farmacológico , Técnicas de Silenciamento de Genes , Humanos , Ácidos Hidroxâmicos/farmacologia , Indóis/farmacologia , Masculino , Camundongos , Camundongos Nus , Mutação de Sentido Incorreto , Necrose , Panobinostat , Proteínas Proto-Oncogênicas B-raf/genética , Proteínas Proto-Oncogênicas B-raf/metabolismo , RNA Interferente Pequeno/genética , Proteína Serina-Treonina Quinases de Interação com Receptores/genética , Sulfonamidas/farmacologia , Vemurafenib , Vorinostat , Ensaios Antitumorais Modelo de Xenoenxerto
11.
Osteoarthritis Cartilage ; 21(4): 589-98, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23333470

RESUMO

OBJECTIVE: Matrix-associated autologous chondrocyte implantation has been used to treat cartilage defects. We developed a biphasic cylindrical osteochondral composite construct for such use, and conducted this study to determine its feasibility for treating osteochondral lesions in human knees. METHOD: Ten patients with symptomatic osteochondral lesions at femoral condyles were treated by replacing pathological tissue with the construct of dl-poly-lactide-co-glycolide, whose lower body was impregnated with ß-tricalcium phosphate and served as osseous phase. The construct had a chamber to load double-minced autologous cartilage, serving as source of chondrocytes. Osteochondral lesion was drill-fashioned a pit of identical dimension as the construct. Chondrocyte-laden construct was press-fit to fill the pit. Postoperative outcome was evaluated using Knee Injury and Osteoarthritis Outcome Score (KOOS) scale up to 24 months. Magnetic resonance image was taken, and sample tissue was collected with second-look arthroscopic needle biopsy at 12 months. Outcome parameters were primarily safety of surgery, and secondarily postoperative change in KOOS and regeneration of hyaline cartilage and cancellous bone. RESULTS: No patient experienced serious adverse events. Postoperative mean KOOS in "symptoms" subscale had not changed significantly from pre-operation until 24 months; whereas those in the other four subscales were significantly higher than pre-operation at 12 and 24 months. Second-look arthroscopy showed completely filled grafted sites, with regenerate cartilaginous surfaces flushed with surrounding native joint surface. Microscopically, regenerated cartilage appeared hyaline. CONCLUSION: This novel construct for chondrocyte implantation is safe for surgical application in knee. It repairs osteochondral lesions of femoral condyles by successful regeneration of hyaline cartilage.


Assuntos
Condrócitos/transplante , Traumatismos do Joelho/cirurgia , Articulação do Joelho/cirurgia , Alicerces Teciduais , Adulto , Artroscopia , Regeneração Óssea/fisiologia , Cartilagem Articular/lesões , Cartilagem Articular/patologia , Cartilagem Articular/fisiologia , Estudos de Viabilidade , Feminino , Humanos , Articulação do Joelho/patologia , Articulação do Joelho/fisiologia , Ácido Láctico , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Osteocondrite Dissecante/cirurgia , Ácido Poliglicólico , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Complicações Pós-Operatórias , Regeneração , Índice de Gravidade de Doença , Engenharia Tecidual/métodos , Resultado do Tratamento , Adulto Jovem
12.
Oncogene ; 32(15): 1910-20, 2013 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-22710713

RESUMO

Past studies have shown that amplified insulin-like growth factor 1 (IGF1)/IGF1 receptor (IGF1-R) signalling has an important role in colorectal cancer (CRC) development, progression and resistance to treatment. In this report, we demonstrate that downregulation of microRNA-497 (miR-497) as a result of DNA copy number reduction is involved in upregulation of IGF1-R in CRC cells. MiR-497 and miR-195 of the miR-15/16/195/424/497 family that share the same 3' untranslated region (3'UTR) binding seed sequence and are predicted to target IGF1-R were concurrently downregulated in the majority of CRC tissues relative to paired adjacent normal mucosa. However, only overexpression of miR-497 led to suppression of the IGF1-R 3'UTR activity and downregulation of the endogenous IGF1-R protein in CRC cells. This was associated with inhibition of cell survival, proliferation and invasion, and increased sensitivity to apoptosis induced by various stimuli including the chemotherapeutic drugs cisplatin and 5-fluorouracil, and the death ligand tumour necrosis factor-related apoptosis-inducing ligand. The biological effect of miR-497 on CRC cells was largely mediated by inhibition of phosphatidylinositol 3-kinase/Akt signalling, as overexpression of an active form of Akt reversed its impact on cell survival and proliferation, recapitulating the effect of overexpression of IGF1-R. Downregulation of miR-497 and miR-195 appeared to associate with copy number loss of a segment of chromosome 17p13.1, where these miRs are located at proximity. Similarly to miR-195, the members of the same miR family, miR-424 that was upregulated, and miR-15a, miR-15b and miR-16 that were unaltered in expression in CRC tissues compared with paired adjacent normal mucosa, did not appear to have a role in regulating the expression of IGF1-R. Taken together, these results identify downregulation of miR-497 as an important mechanism of upregulation of IGF1-R in CRC cells that contributes to malignancy of CRC.


Assuntos
Neoplasias Colorretais/genética , Neoplasias Colorretais/metabolismo , Variações do Número de Cópias de DNA , MicroRNAs/metabolismo , Receptor IGF Tipo 1/metabolismo , Regiões 3' não Traduzidas , Apoptose/genética , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular/genética , Cisplatino/farmacologia , Progressão da Doença , Regulação para Baixo , Resistencia a Medicamentos Antineoplásicos/genética , Fluoruracila/farmacologia , Regulação Neoplásica da Expressão Gênica , Humanos , Fator de Crescimento Insulin-Like I/metabolismo , MicroRNAs/genética , Invasividade Neoplásica/genética , Fosfatidilinositol 3-Quinase/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/genética
13.
Cell Death Dis ; 3: e337, 2012 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-22739989

RESUMO

Endoplasmic reticulum (ER) stress triggers apoptosis by activating Bim in diverse types of cells, which involves dephosphorylation of Bim(EL) by protein phosphatase 2A (PP2A). However, melanoma cells are largely resistant to ER stress-induced apoptosis, suggesting that Bim activation is suppressed in melanoma cells undergoing ER stress. We show here that ER stress reduces PP2A activity leading to increased ERK activation and subsequent phosphorylation and proteasomal degradation of Bim(EL). Despite sustained upregulation of Bim at the transcriptional level, the Bim(EL) protein expression was downregulated after an initial increase in melanoma cells subjected to pharmacological ER stress. This was mediated by increased activity of ERK, whereas the phosphatase activity of PP2A was reduced by ER stress in melanoma cells. The increase in ERK activation was, at least in part, due to reduced dephosphorylation by PP2A, which was associated with downregulation of the PP2A catalytic C subunit. Notably, instead of direct dephosphorylation of Bim(EL), PP2A inhibited its phosphorylation indirectly through dephosphorylation of ERK in melanoma cells. Taken together, these results identify downregualtion of PP2A activity as an important protective mechanism of melanoma cells against ER stress-induced apoptosis.


Assuntos
Estresse do Retículo Endoplasmático , Melanoma/metabolismo , Proteína Fosfatase 2/genética , Apoptose , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Proteína 11 Semelhante a Bcl-2 , Linhagem Celular Tumoral , Regulação para Baixo , Humanos , Melanoma/genética , Melanoma/patologia , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Fosforilação , Proteína Fosfatase 2/metabolismo , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Transdução de Sinais , Transcrição Gênica , Regulação para Cima
14.
Oncogene ; 30(34): 3716-26, 2011 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-21423203

RESUMO

Past studies have shown that upregulation of the anti-apoptotic Bcl-2 family protein Mcl-1 is a major adaptive mechanism of melanoma cells to endoplasmic reticulum (ER) stress, and has an important role in resistance of the cells to apoptosis. In this study, we show that the increase in transcription of Mcl-1 in melanoma cells triggered by pharmacological ER stress inducers is mediated by the transcription factor Ets-1. By incremental deletion analysis of the Mcl-1 promoter, we identified a DNA fragment containing an Ets-1 binding site that is transcriptionally responsive to ER stress. Mutations in the Ets-1 binding site or knockdown of Ets-1 inhibited the increase in Mcl-1, indicating that Ets-1 has a critical role in transcriptional upregulation of Mcl-1. Similar to Mcl-1, Ets-1 was transcriptionally upregulated by ER stress. This was mediated by the IRE1α/XBP-1 branch of the unfolded protein response, as upregulation of Ets-1 was inhibited in melanoma cell lines deficient in IRE1α or XBP-1 established by short hairpin RNA knockdown. Activation of the PI3k/Akt pathway downstream of XBP-1 was also involved, in that inhibition of the pathway blocked upregulation of Ets-1. Inhibition of Ets-1 enhanced ER stress-induced apoptosis in melanoma cell lines and in fresh melanoma isolates, recapitulating the effect of inhibition of Mcl-1. These results reveal a key mechanism by which Mcl-1 is transcriptionally upregulated in melanoma cells by ER stress, and identify Ets-1 as a potential target for inhibition to sensitize melanoma cells to apoptosis.


Assuntos
Proteínas de Ligação a DNA/fisiologia , Retículo Endoplasmático/metabolismo , Melanoma/metabolismo , Proteína Proto-Oncogênica c-ets-1/fisiologia , Proteínas Proto-Oncogênicas c-bcl-2/fisiologia , Fatores de Transcrição/fisiologia , Regulação para Cima/fisiologia , Apoptose , Sequência de Bases , Western Blotting , Linhagem Celular Tumoral , Imunoprecipitação da Cromatina , Primers do DNA , Ensaio de Desvio de Mobilidade Eletroforética , Humanos , Melanoma/patologia , Proteína de Sequência 1 de Leucemia de Células Mieloides , Reação em Cadeia da Polimerase , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas c-bcl-2/genética , Fatores de Transcrição de Fator Regulador X , Transcrição Gênica , Proteína 1 de Ligação a X-Box
15.
Cell Death Differ ; 17(8): 1354-67, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20300110

RESUMO

Past studies have identified a number of distinct mechanisms that contribute to the resistance of melanoma cells against apoptosis induced by TNF-related apoptosis-inducing ligand (TRAIL). In this report we show that cystatin B is another endogenous inhibitor of TRAIL-induced apoptosis. Cystatin B-deficient melanoma cell lines established by shRNA knockdown displayed increased apoptosis that was associated with enhanced activation of caspase-8 induced by TRAIL. This was not related to the inhibitory effect of cystatin B on the lysosomal cysteine proteases, cathepsin B and L, as they did not have a role in TRAIL-induced apoptosis in most melanoma cell lines even when cystatin B was inhibited. Instead, sensitization of melanoma cells to TRAIL-induced apoptosis by inhibition of cystatin B appeared associated with decreased stability of FLIP(L) as the levels of FLIP(L) were reduced because of shortened half-life time in melanoma cells deficient in cystatin B. In contrast, over-expression of cystatin B increased the levels of FLIP(L), decreased the amount of the E3 ligase Itch associated with FLIP(L), and reduced FLIP(L) ubiquitination. Inhibition of Itch by siRNA restored the levels of FLIP(L) and blocked sensitization to TRAIL-induced apoptosis associated with deficiency in cystatin B. Taken together, these results indicate that cystatin B regulates Itch-mediated degradation of FLIP(L) and thereby TRAIL-induced apoptosis in melanoma cells.


Assuntos
Apoptose , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/metabolismo , Cistatina B/metabolismo , Melanoma/metabolismo , Proteínas Repressoras/metabolismo , Ligante Indutor de Apoptose Relacionado a TNF/farmacologia , Ubiquitina-Proteína Ligases/metabolismo , Caspase 8/metabolismo , Linhagem Celular Tumoral , Cistatina B/genética , Técnicas de Silenciamento de Genes , Humanos , Melanoma/enzimologia , Interferência de RNA , RNA Interferente Pequeno/metabolismo
16.
Cell Death Dis ; 1: e69, 2010 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-21364673

RESUMO

Bim is known to be critical in killing of melanoma cells by inhibition of the RAF/MEK/ERK pathway. However, the potential role of the most potent apoptosis-inducing isoform of Bim, Bim(S), remains largely unappreciated. Here, we show that inhibition of the mutant B-RAF(V600E) triggers preferential splicing to produce Bim(S), which is particularly important in induction of apoptosis in B-RAF(V600E) melanoma cells. Although the specific B-RAF(V600E) inhibitor PLX4720 upregulates all three major isoforms of Bim, Bim(EL), Bim(L), and Bim(S), at the protein and mRNA levels in B-RAF(V600E) melanoma cells, the increase in the ratios of Bim(S) mRNA to Bim(EL) and Bim(L) mRNA indicates that it favours Bim(S) splicing. Consistently, enforced expression of B-RAF(V600E) in wild-type B-RAF melanoma cells and melanocytes inhibits Bim(S) expression. The splicing factor SRp55 appears necessary for the increase in Bim(S) splicing, as SRp55 is upregulated, and its inhibition by small interfering RNA blocks induction of Bim(S) and apoptosis induced by PLX4720. The PLX4720-induced, SRp55-mediated increase in Bim(S) splicing is also mirrored in freshly isolated B-RAF(V600E) melanoma cells. These results identify a key mechanism for induction of apoptosis by PLX4720, and are instructive for sensitizing melanoma cells to B-RAF(V600E) inhibitors.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Apoptose , Melanoma/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Proto-Oncogênicas B-raf/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Substituição de Aminoácidos , Proteínas Reguladoras de Apoptose/genética , Proteína 11 Semelhante a Bcl-2 , Linhagem Celular Tumoral , Humanos , Indóis/farmacologia , Proteínas de Membrana/genética , Mutação , Proteínas Nucleares/metabolismo , Fosfoproteínas/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas B-raf/antagonistas & inibidores , Proteínas Proto-Oncogênicas B-raf/genética , Interferência de RNA , Splicing de RNA , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/metabolismo , Proteínas de Ligação a RNA , Fatores de Processamento de Serina-Arginina , Sulfonamidas/farmacologia
17.
Osteoarthritis Cartilage ; 16(3): 343-51, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17804262

RESUMO

OBJECTIVE: To assess how magnetic fields (MFs), with or without concurrent radio frequency (RF), influence chondrocytes and knee joint repair, we applied an MF strength via magnetic resonance imaging (MRI) slightly greater than the frequently used dosage in the clinics and examined the effects of these treatments in vitro on human chondrocytes and in vivo in pigs. METHODS: Human chondrocytes were directly exposed to a 3-tesla (T) magnetic field (MF group) or a 3-T static magnetic field plus 125.3 MHz radio frequency (MF+RF group), and cell proliferation, apoptosis, cytosolic Ca2+ ([Ca2+]i) fluxes and expression of the apoptosis-related proteins of the treated cells were examined to assess the effects of the treatments. In the pig study, we examined the effects of the treatments on the recovery of surgically damaged pig knees. RESULTS: A 3-T static MF and RF suppressed cell growth and induced apoptosis through p53, p21, p27 and Bax protein expression. In the pig model, we found that MRI surveillance had a deleterious effect on the recovery of the damaged knee cartilage. CONCLUSION: Magnetic strength, with or without concurrent RF, suppressed chondrocyte growth in vitro and affected recovery of damaged knee cartilage in vivo in the pig model. These results may be specific to the parameters used in this study and may not apply to other situations, field strengths, forms of cartilage injury, or animal species.


Assuntos
Cálcio/metabolismo , Fenômenos Fisiológicos Celulares/efeitos da radiação , Condrócitos/efeitos da radiação , Imageamento por Ressonância Magnética/efeitos adversos , Regeneração/efeitos da radiação , Joelho de Quadrúpedes/fisiologia , Adulto , Animais , Western Blotting , Células Cultivadas , Condrócitos/citologia , Condrócitos/metabolismo , Colágeno Tipo II/genética , Fragmentação do DNA/efeitos da radiação , Modelos Animais de Doenças , Citometria de Fluxo , Fura-2 , Expressão Gênica/efeitos da radiação , Genes p53/genética , Humanos , Técnicas In Vitro , Imageamento por Ressonância Magnética/métodos , Pessoa de Meia-Idade , Joelho de Quadrúpedes/lesões , Suínos , Fatores de Tempo
18.
Skeletal Radiol ; 31(11): 624-30, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12395273

RESUMO

OBJECTIVE: To evaluate the relationship between joint fluid, intramedullary pressure (IMP), bone marrow edema, and stages of osteonecrosis of the femoral head (ONFH). MATERIAL AND METHODS: We reviewed the magnetic resonance (MR) images of 28 patients with 40 documented ONFHs. IMP was measured in 16 symptomatic hips. The amount of joint fluid was graded as 0 (no fluid), 1 (fluid <5 mm in width), or 2 (fluid > or = 5 mm in width) adjacent to the entire length of the femoral neck. Associated focal and diffuse bone marrow abnormalities were evaluated. A control group of 29 recruited individuals without symptoms related to hip disease were examined. Follow-up MR images were obtained in four patients (five affected hips) 6-10 months after core decompression. RESULTS: Of the 40 affected hips, the severity of ONFH was divided into stages 0 (n=4), I (n=28), and II (n=8 hips) on MR findings. The correlation of joint fluid to IMP and to the presence of bone marrow edema was poor. The amount of joint fluid correlated significantly with the stage of ONFH. None of the five affected hips showed decreased joint fluid on follow-up MR images. CONCLUSION: The amount of joint fluid correlates well with the stage of ONFH. The amount of joint fluid does not correlate with IMP or bone marrow edema.


Assuntos
Necrose da Cabeça do Fêmur/patologia , Articulação do Quadril/patologia , Imageamento por Ressonância Magnética , Líquido Sinovial , Adulto , Idoso , Idoso de 80 Anos ou mais , Medula Óssea/patologia , Medula Óssea/fisiopatologia , Edema/patologia , Feminino , Necrose da Cabeça do Fêmur/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade
19.
Br J Cancer ; 87(2): 218-24, 2002 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-12107846

RESUMO

Diffusely infiltrative astrocytic tumours are the most common neoplasms in the human brain. To localise putative tumour suppressor loci that are involved in low-grade astrocytomas, we performed high-resolution genome-wide allelotype analysis on 17 fibrillary astrocytomas. Non-random allelic losses were identified on chromosomal arms 10p (29%), 10q (29%), 14q (35%), 17p (53%), and 19q (29%), with their respective common regions of deletions delineated at 10p14-15.1, 10q25.1-qter, 14q212.2-qer, 17p11.2-pter and 19q12-13.4. These results suggest that alterations of these chromosomal regions play important roles in the development of astrocytoma. We also allelotyped 21 de novo glioblastoma multiforme with an aim to unveil genetic changes that are common to both types of astrocytic tumours. Non-random allelic losses were identified on 9p (67%), 10p (62%), 10q (76%), 13q (60%), 14q (50%), and 17p (65%). Allelic losses of 10p, 10q, 14q and 17p were common genetic alterations detectable in both fibrillary astrocytomas and glioblastoma multiforme. In addition, two common regions of deletions on chromosome 14 were mapped to 14q22.3-32.1 and 14q32.1-qter, suggesting the presence of two putative tumour suppressor genes. In conclusion, our comprehensive allelotype analysis has unveiled several critical tumour suppressor loci that are involved in the development of fibrillary astrocytomas and glioblastoma multiforme. Although these two types of brain tumours are believed to evolve from different genetic pathways, they do share some common genetic changes. Our results indicate that deletions of chromosome 14q is a recurrent genetic event in the development of astrocytoma and highlight the subchromosomal regions on this chromosome that are likely to contain putative tumour suppressor genes involved in the oncogenesis of astrocytic tumours.


Assuntos
Astrocitoma/genética , Neoplasias Encefálicas/genética , Cromossomos Humanos Par 14/genética , Adulto , Alelos , Desequilíbrio Alélico , Astrocitoma/patologia , Neoplasias Encefálicas/patologia , Aberrações Cromossômicas , Cromossomos Humanos/genética , Cromossomos Humanos/ultraestrutura , Cromossomos Humanos Par 14/ultraestrutura , DNA de Neoplasias/genética , Feminino , Deleção de Genes , Genótipo , Glioblastoma/genética , Glioblastoma/patologia , Humanos , Perda de Heterozigosidade , Masculino
20.
J Formos Med Assoc ; 99(6): 472-6, 2000 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10925553

RESUMO

BACKGROUND AND PURPOSE: Recurrent anterior shoulder dislocation is a serious condition, for which the Bankart procedure is a standard treatment. Having made three modifications to the original procedure, we examined the efficacy of this modified Bankart procedure in the treatment of patients with recurrent anterior shoulder dislocation. PATIENTS AND METHODS: The medical records of 21 patients who received a modified Bankart procedure for recurrent anterior shoulder dislocation during the period from 1989 through 1998 were retrospectively analyzed. The average age at initial dislocation was 22 +/- 5 years. The average postoperative follow-up period was 41 +/- 16 months. Three of the patients complained of mild shoulder pain before their operation. RESULTS: The postoperative loss of external rotation and abduction compared with the nonoperated side was 9 +/- 4 degrees and 5 +/- 4 degrees, respectively. There were no limitations in daily activities during follow-up. No patient had shoulder pain after surgery. Redislocation occurred in one patient during the follow-up period. Patient satisfaction was rated as excellent by 20 (96%) patients and poor by one. CONCLUSION: This modified Bankart procedure is a technically easy operation with a low complication rate, a high rate of patient satisfaction, and a low redislocation rate. It is a procedure of choice for the management of traumatic recurrent anterior shoulder dislocation.


Assuntos
Luxação do Ombro/cirurgia , Adolescente , Adulto , Humanos , Complicações Pós-Operatórias , Recidiva , Estudos Retrospectivos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA