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1.
Proc Natl Acad Sci U S A ; 114(23): E4631-E4640, 2017 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-28533408

RESUMO

Like many complex human diseases, esophageal squamous cell carcinoma (ESCC) is known to cluster in families. Familial ESCC cases often show early onset and worse prognosis than the sporadic cases. However, the molecular genetic basis underlying the development of familial ESCC is mostly unknown. We reported that SLC22A3 is significantly down-regulated in nontumor esophageal tissues from patients with familial ESCC compared with tissues from patients with sporadic ESCCs. A-to-I RNA editing of the SLC22A3 gene results in its reduced expression in the nontumor esophageal tissues of familial ESCCs and is significantly correlated with lymph node metastasis. The RNA-editing enzyme ADAR2, a familial ESCC susceptibility gene identified by our post hoc genome-wide association study, is positively correlated with the editing level of SLC22A3 Moreover, functional studies showed that SLC22A3 is a metastasis suppressor in ESCC, and deregulation of SLC22A3 facilitates cell invasion and filopodia formation by reducing its direct association with α-actinin-4 (ACTN4), leading to the increased actin-binding activity of ACTN4 in normal esophageal cells. Collectively, we now show that A-to-I RNA editing of SLC22A3 contributes to the early development and progression of familial esophageal cancer in high-risk individuals.


Assuntos
Carcinoma de Células Escamosas/genética , Neoplasias Esofágicas/genética , Proteínas de Transporte de Cátions Orgânicos/genética , Edição de RNA , Actinina/metabolismo , Adenosina Desaminase/genética , Adenosina Desaminase/metabolismo , Adulto , Idoso , Animais , Carcinoma de Células Escamosas/patologia , Carcinoma de Células Escamosas/secundário , Linhagem Celular , Linhagem Celular Tumoral , Movimento Celular , Progressão da Doença , Regulação para Baixo , Neoplasias Esofágicas/patologia , Neoplasias Esofágicas/secundário , Carcinoma de Células Escamosas do Esôfago , Esôfago/citologia , Esôfago/metabolismo , Técnicas de Silenciamento de Genes , Estudo de Associação Genômica Ampla , Humanos , Metástase Linfática/genética , Masculino , Camundongos , Camundongos SCID , Pessoa de Meia-Idade , Invasividade Neoplásica/genética , Proteínas de Transporte de Cátions Orgânicos/deficiência , Proteínas de Transporte de Cátions Orgânicos/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Fatores de Risco
2.
Carcinogenesis ; 37(3): 320-332, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26785734

RESUMO

Esophageal squamous cell carcinoma (ESCC) is an aggressive malignancy; its mechanisms of development and progression are poorly understood. By high-throughput transcriptome sequencing (RNA-Seq) profiling of three pairs of primary ESCCs and their corresponding non-tumorous tissues, we identified that prostate stem cell antigen (PSCA), a gene that encodes a glycosylphosphatidylinositol-anchored protein, is significantly downregulated in ESCC. Here, we reported decreased expression of PSCA in 188/218 (86.2%) of primary ESCC cases and was negatively regulated by its transcription factor sex-determining region Y-box5 that was significantly associated with the poor differentiation (P = 0.003), increased lymph node metastasis (P < 0.0001), advanced stage (P = 0.007), and disease-specific survival (P < 0.0001), but not associated with the recently reported transcrible rs2294008 (C > T) polymorphism in ESCC. Functional studies showed that PSCA could arrest cell cycle progression and promote cell differentiation independent of the start codon polymorphism. Further mechanistic studies revealed that retinoblastoma 1-inducible coiled-coil 1 (RB1CC1), a key signaling node to regulate cellular proliferation and differentiation, interacted specifically with PSCA in ESCC cells. Binding of PSCA and RB1CC1 in cytoplasm resulted in stabilization and translocation of RB1CC1 into nucleus, thereby activating key factors involved in cell cycle arrest and differentiation. Collectively, our data provide a novel molecular mechanism for the tumor suppressor role of PSCA and may help design effective therapy targeting PSCA-RB1CC1 pathway to control esophageal cancer growth and differentiation.


Assuntos
Antígenos de Neoplasias/metabolismo , Carcinoma de Células Escamosas/patologia , Neoplasias Esofágicas/patologia , Proteínas de Neoplasias/metabolismo , Transporte Proteico/fisiologia , Proteínas Tirosina Quinases/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Animais , Proteínas Relacionadas à Autofagia , Imunoprecipitação da Cromatina , Ensaio de Desvio de Mobilidade Eletroforética , Carcinoma de Células Escamosas do Esôfago , Proteínas Ligadas por GPI/metabolismo , Xenoenxertos , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Imuno-Histoquímica , Camundongos , Camundongos Nus , Análise Serial de Tecidos
3.
Cancer Res ; 73(7): 2298-309, 2013 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-23436800

RESUMO

Loss of chromosome 19p is one of the most frequent allelic imbalances in esophageal squamous cell carcinoma (ESCC), suggesting the existence of one or more tumor suppressor genes within this region. In this study, we investigated a role in ESCCs for a candidate tumor suppressor gene located at 19p13.3, the Ras-like small GTPase DIRAS1. Downregulation of DIRAS1 occurred in approximately 50% of primary ESCCs where it was associated significantly with advanced clinical stage, lymph node metastasis, and poor overall survival. LOH and promoter methylation analyses suggested that loss of DIRAS1 expression was mediated by epigenetic mechanisms. Functional studies established that ectopic re-expression of DIRAS1 in ESCC cells inhibited cell proliferation, clonogenicity, cell motility, and tumor formation. Mechanistic investigations suggested that DIRAS1 acted through extracellular signal-regulated kinase (ERK1/2; MAPK3/1) and p38 mitogen-activated protein kinase (MAPK; MAPK14) signaling to trigger BAD Ser112 dephosphorylation and matrix metalloproteinase (MMP)2/9 transcriptional inactivation to promote apoptosis and inhibit metastasis, respectively. Taken together, our results revealed that DIRAS1 has a pivotal function in ESCC pathogenesis, with possible use as a biomarker and intervention point for new therapeutic strategies.


Assuntos
Apoptose , Carcinoma de Células Escamosas/mortalidade , Metilação de DNA , Neoplasias Esofágicas/mortalidade , GTP Fosfo-Hidrolases/genética , Regulação Neoplásica da Expressão Gênica , Genes Supressores de Tumor , Proteínas Supressoras de Tumor/genética , Western Blotting , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/secundário , Adesão Celular , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Variações do Número de Cópias de DNA , Regulação para Baixo , Epigênese Genética , Neoplasias Esofágicas/genética , Neoplasias Esofágicas/patologia , Feminino , GTP Fosfo-Hidrolases/metabolismo , Humanos , Técnicas Imunoenzimáticas , Perda de Heterozigosidade , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Prognóstico , Regiões Promotoras Genéticas/genética , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Taxa de Sobrevida , Análise Serial de Tecidos , Proteínas Supressoras de Tumor/metabolismo
4.
Carcinogenesis ; 34(2): 454-63, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23125220

RESUMO

Nasopharyngeal carcinoma (NPC) is a type of head and neck cancer with significantly high prevalence in Southern China. Unlike other head and neck cancers, mutations or deletions of tumor suppressor genes in NPC are not common. Recently, downregulation of tumor suppressor genes expression by microRNA (miRNA) is increasingly recognized as an important mechanism of nasopharyngeal tumorigenesis. In this study, we reported that microRNA-144 (miR-144) was frequently upregulated in NPC specimens and cell lines. Repression of miR-144 significantly decreased cell proliferation, clonogenicity, migration, invasion and tumor formation in nude mice, while restoring miR-144 in miR-144-attenuated NPC cells exhibited a strong tumorigenic role. Further, we found that miR-144 was inversely correlated with the tumor suppressor gene phosphatase and tensin homolog (PTEN) in NPC specimens and cell lines, and then we identified PTEN as a direct target of miR-144 in NPC cell lines. PTEN downregulation in miR-144-attenuated cells could increase cell growth, migration and invasion. Mechanistic investigations revealed that miR-144 suppressed the expression of PTEN to increase the expression of pAkt and cyclin D1 to promote G(1)-phase transition and decrease E-cadherin to promote migration and invasion. Taken together, we provide compelling evidence that miR-144 functions as an onco-miRNA in NPC, and its oncoeffects are mediated chiefly by repressing PTEN expression to activate the PI3K/Akt pathway.


Assuntos
Movimento Celular , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , MicroRNAs/genética , Neoplasias Nasofaríngeas/patologia , Nasofaringe/metabolismo , PTEN Fosfo-Hidrolase/antagonistas & inibidores , Adulto , Idoso , Animais , Apoptose , Western Blotting , Carcinoma , Estudos de Casos e Controles , Adesão Celular , Ciclo Celular , Feminino , Humanos , Técnicas Imunoenzimáticas , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Pessoa de Meia-Idade , Carcinoma Nasofaríngeo , Neoplasias Nasofaríngeas/genética , Invasividade Neoplásica , PTEN Fosfo-Hidrolase/genética , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células Tumorais Cultivadas
5.
PLoS One ; 7(9): e44636, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22957092

RESUMO

Deletion of the short arm of chromosome 3 is one of the most frequent genetic alterations in many solid tumors including nasopharyngeal carcinoma (NPC), suggesting the existence of one or more tumor suppressor genes (TSGs) within the frequently deleted region. A putative TSG RBMS3 (RNA binding motif, single stranded interacting protein 3), located at 3p24-p23, has been identified in our previous study. Here, we reported that downregulation of RBMS3 was detected in 3/3 NPC cell lines and 13/15 (86.7%) primary NPC tissues. Functional studies using both overexpression and suppression systems demonstrated that RBMS3 has a strong tumor suppressive role in NPC. The tumor suppressive mechanism of RBMS3 was associated with its role in cell cycle arrest at the G1/S checkpoint by upregulating p53 and p21, downregulating cyclin E and CDK2, and the subsequent inhibition of Rb-ser780. Further analysis demonstrated that RBMS3 had a pro-apoptotic role in a mitochondrial-dependent manner via activation of caspase-9 and PARP. Finally, RBMS3 inhibited microvessel formation, which may be mediated by down-regulation of MMP2 and ß-catenin and inactivation of its downstream targets, including cyclin-D1, c-Myc, MMP7, and MMP9. Taken together, our findings define a function for RBMS3 as an important tumor suppressor gene in NPC.


Assuntos
Cromossomos Humanos Par 3 , Neoplasias Nasofaríngeas/metabolismo , Proteínas de Ligação a RNA/fisiologia , Transativadores/fisiologia , Adulto , Idoso , Apoptose , Carcinoma , Ciclo Celular , Linhagem Celular Tumoral , Proliferação de Células , Transformação Celular Neoplásica , Regulação para Baixo , Feminino , Deleção de Genes , Perfilação da Expressão Gênica , Inativação Gênica , Genes Supressores de Tumor , Humanos , Masculino , Microcirculação , Pessoa de Meia-Idade , Carcinoma Nasofaríngeo , Neoplasias Nasofaríngeas/patologia , Neovascularização Patológica , Proteínas de Ligação a RNA/metabolismo , Transativadores/metabolismo
6.
Gut ; 61(4): 562-75, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21813470

RESUMO

BACKGROUND AND AIMS: The authors have previously isolated a putative oncogene, eukaryotic initiation factor 5A2 (EIF5A2) from 3q26. In this study, EIF5A2 was characterised for its role in colorectal carcinoma (CRC) aggressiveness and underlying molecular mechanisms. METHODS: The expression dynamics of EIF5A2 were examined by immunohistochemistry in a cohort of carcinomatous and non-neoplastic colorectal tissues and cells. A series of in-vivo and in-vitro assays was performed to elucidate the function of EIF5A2 in CRC and its underlying mechanisms. RESULTS: The overexpression of EIF5A2 was examined by immunohistochemistry in 102/229 (44.5%) CRC patients, and it was significantly correlated with tumour metastasis and determined to be an independent predictor of shortened survival (p<0.05). Ectopic overexpression of EIF5A2 in CRC cells enhanced cell motility and invasion in vitro and tumour metastasis in vivo, and induced epithelial-mesenchymal transition (EMT). The depletion of EIF5A2 expression prevented CRC cell invasiveness and inhibited EMT. Importantly, the metastasis-associated protein 1 (MTA1) gene was identified as a potential downstream target of EIF5A2 in CRC cells, and knockdown of MTA1 eliminated the augmentation of carcinoma cell migration, invasion and EMT by ectopic EIF5A2. The overexpression of EIF5A2 in CRC cells substantially enhanced the enrichment of c-myc on the promoter of MTA1, and MTA1 upregulation by EIF5A2 was partly dependent on c-myc. CONCLUSION: The data suggest that EIF5A2 plays an important oncogenic role in CRC aggressiveness by the upregulation of MTA1 to induce EMT, and EIF5A2 could be employed as a novel prognostic marker and/or effective therapeutic target for CRC.


Assuntos
Neoplasias Colorretais/metabolismo , Transição Epitelial-Mesenquimal/fisiologia , Histona Desacetilases/biossíntese , Fatores de Iniciação de Peptídeos/fisiologia , Proteínas de Ligação a RNA/fisiologia , Proteínas Repressoras/biossíntese , Regulação para Cima/fisiologia , Animais , Biomarcadores Tumorais/metabolismo , Neoplasias Colorretais/patologia , Proteínas de Ligação a DNA/fisiologia , Feminino , Humanos , Masculino , Camundongos , Camundongos SCID , Gradação de Tumores , Invasividade Neoplásica , Proteínas de Neoplasias/metabolismo , Proteínas de Neoplasias/fisiologia , Estadiamento de Neoplasias , Fatores de Iniciação de Peptídeos/metabolismo , Prognóstico , Proteínas de Ligação a RNA/metabolismo , Reação em Cadeia da Polimerase em Tempo Real/métodos , Transativadores , Fatores de Transcrição/fisiologia , Células Tumorais Cultivadas , Fator de Iniciação de Tradução Eucariótico 5A
7.
Nucleic Acids Res ; 40(1): 196-205, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21911360

RESUMO

Pairing of a given E3 ubiquitin ligase with different E2s allows synthesis of ubiquitin conjugates of different topologies. While this phenomenon contributes to functional diversity, it remains largely unknown how a single E3 ubiquitin ligase recognizes multiple E2s, and whether identical structural requirements determine their respective interactions. The E3 ubiquitin ligase RNF8 that plays a critically important role in transducing DNA damage signals, interacts with E2s UBCH8 and UBC13, and catalyzes both K48- and K63-linked ubiquitin chains. Interestingly, we report here that a single-point mutation (I405A) on the RNF8 polypeptide uncouples its ability in catalyzing K48- and K63-linked ubiquitin chain formation. Accordingly, while RNF8 interacted with E2s UBCH8 and UBC13, its I405A mutation selectively disrupted its functional interaction with UBCH8, and impaired K48-based poly-ubiquitylation reactions. In contrast, RNF8 I405A preserved its interaction with UBC13, synthesized K63-linked ubiquitin chains, and assembled BRCA1 and 53BP1 at sites of DNA breaks. Together, our data suggest that RNF8 regulates K48- and K63-linked poly-ubiquitylation via differential RING-dependent interactions with its E2s UBCH8 and UBC13, respectively.


Assuntos
Lisina/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitinação , Sequência de Aminoácidos , Animais , Células Cultivadas , Dano ao DNA , Camundongos , Dados de Sequência Molecular , Mutação Puntual , Complexo de Endopeptidases do Proteassoma/metabolismo , Estabilidade Proteica , Transdução de Sinais , Enzimas de Conjugação de Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/química , Ubiquitina-Proteína Ligases/genética
8.
PLoS One ; 6(7): e21816, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21760911

RESUMO

BACKGROUND:  IL-17A is a pro-inflammatory cytokine that plays important role in inflammatory disease pathology and tumor microenvironment. The aim of this study is to investigate the effect of IL-17A on the progression of hepatocellular carcinoma (HCC). METHODOLOGY AND PRINCIPAL FINDING: Expression pattern of IL-17A in clinical HCC samples (n = 43) was determined by immunohistochemistry staining. Transcript levels of MMP2, MMP9 and IL-17A were measured in another 50 pairs (including tumor and related non-tumor tissues) HCC samples. Cell growth, focus formation, cell migration, invasion and western blot assays were used to characterize the functional and signaling mechanisms in IL-17A-treated HCC. Association study was used to identify clinical significance of IL-17A in HCC. Compared with paired non-tumor tissue, higher frequency of IL-17A-positive cells was detected in tumor tissues in HCCs with metastasis, and the frequency of IL-17A-positive cells was also significantly associated with poor prognosis of HCC (P = 0.01). Functional study found that IL-17A could promote HCC cell migration and invasion. Further molecular analysis also showed that IL-17A could upregulate MMP2 and MMP9 expression via NF-κB signaling activation. CONCLUSIONS:  IL-17A could promote HCC metastasis by the upregulation of MMP2 and MMP9 expression via activating NF-κB signaling pathway.


Assuntos
Carcinoma Hepatocelular/enzimologia , Carcinoma Hepatocelular/patologia , Interleucina-17/farmacologia , Neoplasias Hepáticas/patologia , Metaloproteinase 2 da Matriz/biossíntese , Metaloproteinase 9 da Matriz/biossíntese , NF-kappa B/metabolismo , Idoso , Carcinoma Hepatocelular/genética , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Indução Enzimática/efeitos dos fármacos , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Feminino , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Neoplasias Hepáticas/enzimologia , Neoplasias Hepáticas/genética , Masculino , Metaloproteinase 2 da Matriz/genética , Metaloproteinase 9 da Matriz/genética , Pessoa de Meia-Idade , Análise Multivariada , Invasividade Neoplásica , Metástase Neoplásica , Prognóstico , Proteínas Recombinantes/farmacologia , Análise de Sobrevida , Regulação para Cima/efeitos dos fármacos
9.
Gut ; 60(12): 1635-43, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21672941

RESUMO

OBJECTIVES: Interaction between neoplastic and stromal cells plays an important role in tumour progression. It was recently found that WNT2 was frequently overexpressed in fibroblasts isolated from tumour tissue tumour fibroblasts (TF) compared with fibroblasts from non-tumour tissue normal fibroblasts in oesophageal squamous cell carcinoma (OSCC). This study aimed to investigate the effect of TF-secreted Wnt2 in OSCC development via the tumour-stroma interaction. METHODS: Quantitative PCR, western blotting, immunohistochemistry and immunofluorescence were used to study the expression pattern of Wnt2 and its effect on the Wnt/ß-catenin pathway. A Wnt2-secreting system was established in Chinese hamster ovary cells and its conditioned medium was used to study the role of Wnt2 in cell proliferation and invasion. RESULTS: Expression of Wnt2 could only be detected in TF but not in OSCC cancer cell lines. In OSCC tissues, Wnt2(+) cells were mainly detected in the boundary between stroma and tumour tissue or scattered within tumour tissue. In this study, Wnt2-positive OSCC was defined when five or more Wnt2(+) cells were observed in 200× microscopy field. Interestingly, Wnt2-positive OSCC (22/51 cases) was significantly associated with lymph node metastases (p=0.001), advanced TNM stage (p=0.001) and disease-specific survival (p<0.0001). Functional study demonstrated that secreted Wnt2 could promote oesophageal cancer cell growth by activating the Wnt/ß-catenin signalling pathway and subsequently upregulated cyclin D1 and c-myc expression. Further study found that Wnt2 could enhance cell motility and invasiveness by inducing epithelial-mesenchymal transition. CONCLUSIONS: TF-secreted Wnt2 acts as a growth and invasion-promoting factor through activating the canonical Wnt/ß-catenin signalling pathway in oesophageal cancer cells.


Assuntos
Neoplasias Esofágicas/metabolismo , Via de Sinalização Wnt/fisiologia , Proteína Wnt2/metabolismo , Animais , Western Blotting , Células CHO , Linhagem Celular Tumoral , Movimento Celular/fisiologia , Proliferação de Células , Cricetinae , Neoplasias Esofágicas/fisiopatologia , Fibroblastos/metabolismo , Fibroblastos/fisiologia , Invasividade Neoplásica/fisiopatologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína Wnt2/fisiologia
10.
J Biol Chem ; 286(25): 22355-61, 2011 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-21558560

RESUMO

Histone ubiquitylation is emerging as an important protective component in cellular responses to DNA damage. The ubiquitin ligases RNF8 and RNF168 assemble ubiquitin chains onto histone molecules surrounding DNA breaks and facilitate retention of DNA repair proteins. Although RNF8 and RNF168 play important roles in repair of DNA double strand breaks, their requirement for cell protection from replication stress is largely unknown. In this study, we uncovered RNF168-independent roles of RNF8 in repair of replication inhibition-induced DNA damage. We showed that RNF8 depletion, but not RNF168 depletion, hyper-sensitized cells to hydroxyurea and aphidicolin treatment. Consistently, hydroxyurea induced persistent single strand DNA lesions and sustained CHK1 activation in RNF8-depleted cells. In line with strict requirement for RAD51-dependent repair of hydroxyurea-stalled replication forks, RNF8 depletion compromised RAD51 accumulation onto single strand DNA lesions, suggesting that impaired replication fork repair may underlie the enhanced cellular sensitivity to replication arrest observed in RNF8-depleted cells. In total, our study highlights the differential requirement for the ubiquitin ligase RNF8 in facilitating repair of replication stress-associated DNA damage.


Assuntos
Dano ao DNA , Replicação do DNA/genética , Proteínas de Ligação a DNA/metabolismo , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Quinase 1 do Ponto de Checagem , Replicação do DNA/efeitos dos fármacos , DNA de Cadeia Simples/genética , DNA de Cadeia Simples/metabolismo , Proteínas de Ligação a DNA/deficiência , Fase G2/efeitos dos fármacos , Fase G2/genética , Células HeLa , Histonas/metabolismo , Humanos , Hidroxiureia/farmacologia , Proteínas Quinases/metabolismo , Transporte Proteico/efeitos dos fármacos , Rad51 Recombinase/metabolismo , Ubiquitina-Proteína Ligases , Ubiquitinação/efeitos dos fármacos
11.
Hepatology ; 51(5): 1624-34, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20209601

RESUMO

UNLABELLED: Loss of 16q is one of the most frequent alterations in many malignancies including hepatocellular carcinomas (HCC), suggesting the existence of a tumor suppressor gene (TSG) within the frequently deleted region. In this report we describe the identification and characterization of one candidate TSG, tyrosine aminotransferase gene (TAT), at 16q22.1. Loss of one TAT allele was detected in 27/50 (54%) of primary HCCs by quantitative real-time polymerase chain reaction. In addition, homo-deletion of TAT alleles was detected in two cases. Down-regulation of TAT was detected in 28/50 (56%) of HCCs, which was significantly associated with the loss of TAT allele and hypermethylation of TAT 5' CpG island (CGI) region (P < 0.001). Functional studies found that TAT has a strong tumor suppressive ability. Introduction of the TAT gene into HCC cell lines could effectively inhibit colony formation in soft agar, foci formation, and tumor formation in nude mice. Further study found that the tumor suppressive mechanism of TAT was associated with its proapoptotic role in a mitochondrial-dependent manner by promoting cytochrome-c release and activating caspase-9 and PARP. CONCLUSION: Taken together, our findings suggest that TAT plays an important suppressive role in the development and progression of HCC.


Assuntos
Carcinoma Hepatocelular/genética , Neoplasias Hepáticas/genética , Tirosina Transaminase/genética , Animais , Apoptose/fisiologia , Caspase 9/metabolismo , Cromossomos Humanos Par 16/genética , Ilhas de CpG , Citocromos c/metabolismo , Metilação de DNA , Regulação para Baixo , Ativação Enzimática , Deleção de Genes , Humanos , Camundongos , Camundongos Nus , RNA Interferente Pequeno/farmacologia
12.
J Clin Invest ; 120(4): 1178-91, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20335658

RESUMO

Chromodomain helicase/ATPase DNA binding protein 1-like gene (CHD1L) is a recently identified oncogene localized at 1q21, a frequently amplified region in hepatocellular carcinoma (HCC). To explore its oncogenic mechanisms, we set out to identify CHD1L-regulated genes using a chromatin immunoprecipitation-based (ChIP-based) cloning strategy in a human HCC cell line. We then further characterized 1 identified gene, ARHGEF9, which encodes a specific guanine nucleotide exchange factor (GEF) for the Rho small GTPase Cdc42. Overexpression of ARHGEF9 was detected in approximately half the human HCC samples analyzed and positively correlated with CHD1L overexpression. In vitro and in vivo functional studies in mice showed that CHD1L contributed to tumor cell migration, invasion, and metastasis by increasing cell motility and inducing filopodia formation and epithelial-mesenchymal transition (EMT) via ARHGEF9-mediated Cdc42 activation. Silencing ARHGEF9 expression by RNAi effectively abolished the invasive and metastatic abilities of CHD1L in mice. Furthermore, investigation of clinical HCC specimens showed that CHD1L and ARHGEF9 were markedly overexpressed in metastatic HCC tissue compared with healthy tissue. Increased expression of CHD1L was often observed at the invasive front of HCC tumors and correlated with venous infiltration, microsatellite tumor nodule formation, and poor disease-free survival. These findings suggest that CHD1L-ARHGEF9-Cdc42-EMT might be a novel pathway involved in HCC progression and metastasis.


Assuntos
Carcinoma Hepatocelular/etiologia , DNA Helicases/fisiologia , Proteínas de Ligação a DNA/fisiologia , Neoplasias Hepáticas/etiologia , Animais , Carcinoma Hepatocelular/patologia , Diferenciação Celular , Linhagem Celular Tumoral , Movimento Celular , Progressão da Doença , Células Endoteliais/patologia , Feminino , Regulação Neoplásica da Expressão Gênica , Fatores de Troca do Nucleotídeo Guanina/genética , Humanos , Neoplasias Hepáticas/patologia , Masculino , Mesoderma/patologia , Camundongos , Camundongos SCID , Invasividade Neoplásica , Metástase Neoplásica , Fatores de Troca de Nucleotídeo Guanina Rho , Proteína cdc42 de Ligação ao GTP/metabolismo
13.
Hepatology ; 51(4): 1255-63, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20112425

RESUMO

UNLABELLED: A high incidence of tumor recurrence and metastasis has been reported in hepatocellular carcinoma (HCC) patients; however, the underlying molecular mechanisms are largely unknown. In the present study a novel metastasis-related gene, eukaryotic initiation factor 5A2 (EIF5A2), was characterized for its role in HCC metastasis and underlying molecular mechanisms. Overexpression of EIF5A2 messenger RNA (mRNA) was detected in 50/81 (61.7%) of HCCs, which was significantly higher than those in nontumorous liver tissues. Compared with matched primary HCC, higher expression of EIF5A2 protein was observed in 25/47 (53.2%) of metastatic tumors. Functional studies found that ectopic expression of EIF5A2 could enhance cancer cell migration and invasion in vitro and tumor metastasis in vivo in an experimental mouse model. Moreover, inhibition of EIF5A by small interfering RNA (siRNA) or deoxyhypusine synthase (DHPS) inhibitor GC7, which inhibits EIF5A2 maturation, could effectively decrease cell motility. Further study found that EIF5A2 was able to induce epithelial-mesenchymal transition (EMT), a key event in tumor invasion and metastasis, characterized by down-regulation of epithelial markers (E-cadherin and beta-catenin) and up-regulation of mesenchymal markers (fibronectin, N-cadherin, alpha-SMA, and vimentin). In addition, EIF5A2 could also activate RhoA/Rac1 to stimulate the formation of stress fiber and lamellipodia. CONCLUSION: EIF5A2 plays an important role in HCC invasion and metastasis by inducing EMT, as well as stimulating cytoskeleton rearrangement through activation of RhoA and Rac1.


Assuntos
Carcinoma Hepatocelular/secundário , Neoplasias Hepáticas/patologia , Fatores de Iniciação de Peptídeos/fisiologia , Adulto , Idoso , Animais , Carcinoma Hepatocelular/patologia , Movimento Celular , Células Epiteliais/patologia , Feminino , Guanina/análogos & derivados , Guanina/farmacologia , Humanos , Masculino , Mesoderma/patologia , Camundongos , Pessoa de Meia-Idade , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/antagonistas & inibidores , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/genética , Fatores de Iniciação de Peptídeos/antagonistas & inibidores , Fatores de Iniciação de Peptídeos/genética , RNA Interferente Pequeno/genética , Proteínas rho de Ligação ao GTP/metabolismo
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