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1.
Mol Carcinog ; 55(1): 15-26, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25408419

RESUMO

The PTTG1-binding factor (PBF) is a transforming gene capable of eliciting tumor formation in xenograft models. However, the precise role of PBF in tumorigenesis and its prognostic value as a cancer biomarker remain largely uncharacterised, particularly in malignancies outside the thyroid. Here, we provide the first evidence that PBF represents a promising prognostic marker in colorectal cancer. Examination of a total of 39 patients demonstrated higher PBF expression at both the mRNA (P = 0.009) and protein (P < 0.0001) level in colorectal tumors compared to matched normal tissue. Critically, PBF was most abundant in colorectal tumors associated with Extramural Vascular Invasion (EMVI), increased genetic instability (GI) and somatic TP53 mutations, all features linked with recurrence and poorer patient survival. We further demonstrate by glutathione-S-transferase (GST) pull-down and coimmunoprecipitation that PBF binds to the tumor suppressor protein p53, as well as to p53 mutants (Δ126-132, M133K, V197E, G245D, I255F and R273C) identified in the colorectal tumors. Importantly, overexpression of PBF in colorectal HCT116 cells interfered with the transcriptional activity of p53-responsive genes such as mdm2, p21 and sfn. Diminished p53 stability (> 90%; P < 0.01) was also evident with a concurrent increase in ubiquitinated p53. Human colorectal tumors with wild-type TP53 and high PBF expression also had low p53 protein levels (P < 0.05), further emphasizing a putative interaction between these genes in vivo. Overall, these results demonstrate an emerging role for PBF in colorectal tumorigenesis through regulating p53 activity, with implications for PBF as a prognostic indicator for invasive tumors.


Assuntos
Neoplasias Colorretais/metabolismo , Proteínas de Membrana/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Animais , Linhagem Celular Tumoral , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Instabilidade Genômica , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas de Membrana/química , Proteínas de Membrana/genética , Camundongos , Invasividade Neoplásica , Prognóstico , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Proto-Oncogene Mas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ensaio Tumoral de Célula-Tronco , Ubiquitinação
2.
Oncotarget ; 6(24): 20570-7, 2015 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-26011941

RESUMO

The triple-negative breast cancer (TNBC) subtype is enriched in cancer stem cells (CSCs) and clinically correlated with the highest rate of recurrence. Several studies implicate the RSK pathway as being pivotal for the growth and proliferation of CSCs, which are postulated to drive tumor relapse. We now address the potential for the newly developed RSK inhibitor LJI308 to target the CSC population and repress TNBC growth and dissemination. Overexpression of the Y-box binding protein-1 (YB-1) oncogene in human mammary epithelial cells (HMECs) drove TNBC tumor formation characterized by a multi-drug resistance phenotype, yet these cells were sensitive to LJI308 in addition to the classic RSK inhibitors BI-D1870 and luteolin. Notably, LJI308 specifically targeted transformed cells as it had little effect on the non-tumorigenic parental HMECs. Loss of cell growth, both in 2D and 3D culture, was attributed to LJI308-induced apoptosis. We discovered CD44+/CD49f+ TNBC cells to be less sensitive to chemotherapy compared to the isogenic CD44-/CD49f- cells. However, inhibition of RSK using LJI308, BI-D1870, or luteolin was sufficient to eradicate the CSC population. We conclude that targeting RSK using specific and potent inhibitors, such as LJI308, delivers the promise of inhibiting the growth of TNBC.


Assuntos
Resistencia a Medicamentos Antineoplásicos/genética , Pteridinas/metabolismo , Neoplasias de Mama Triplo Negativas/genética , Apoptose , Linhagem Celular Tumoral , Proliferação de Células , Feminino , Humanos , Células-Tronco Neoplásicas/patologia , Neoplasias de Mama Triplo Negativas/patologia
3.
Stem Cells ; 32(6): 1437-50, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24648416

RESUMO

There is growing evidence that cancer-initiation could result from epigenetic changes. Y-box binding protein-1 (YB-1) is a transcription/translation factor that promotes the formation of tumors in transgenic mice; however, the underlying molecular events are not understood. To explore this in a human model system, YB-1 was expressed in mammary epithelial cells under the control of a tetracycline-inducible promoter. The induction of YB-1 promoted phenotypes associated with malignancy in three-dimensional breast acini cultures. This was attributed to YB-1 enhancing the expression and activity of the histone acetyltransferase p300 leading to chromatin remodeling. Specifically, this relaxation of chromatin allowed YB-1 to bind to the BMI1 promoter. The induction of BMI1 engaged the Polycomb complex resulting in histone H2A ubiquitylation and repression of the CDKN2A locus. These events manifested functionally as enhanced self-renewal capacity that occurred in a BMI1-dependent manner. Conversely, p300 inhibition with anacardic acid prevented YB-1 from binding to the BMI1 promoter and thereby subverted self-renewal. Despite these early changes, full malignant transformation was not achieved until RSK2 became overexpressed concomitant with elevated human telomerase reverse transcriptase (hTERT) activity. The YB-1/RSK2/hTERT expressing cells formed tumors in mice that were molecularly subtyped as basal-like breast cancer. We conclude that YB-1 cooperates with p300 to allow BMI1 to over-ride p16(INK4a) -mediated cell cycle arrest enabling self-renewal and the development of aggressive breast tumors.


Assuntos
Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Mama/patologia , Transformação Celular Neoplásica/metabolismo , Montagem e Desmontagem da Cromatina , Células Epiteliais/metabolismo , Proteína 1 de Ligação a Y-Box/metabolismo , Células Acinares/metabolismo , Células Acinares/patologia , Animais , Neoplasias da Mama/genética , Linhagem Celular Tumoral , Proliferação de Células , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/patologia , Reprogramação Celular/genética , Montagem e Desmontagem da Cromatina/genética , Proteína p300 Associada a E1A/metabolismo , Células Epiteliais/patologia , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos , Camundongos Transgênicos , Modelos Biológicos , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 1/metabolismo , Transcrição Gênica , Regulação para Cima/genética
4.
Endocrinology ; 155(4): 1222-34, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24506068

RESUMO

The PTTG1-binding factor (PBF/PTTG1IP) has an emerging repertoire of roles, especially in thyroid biology, and functions as a protooncogene. High PBF expression is independently associated with poor prognosis and lower disease-specific survival in human thyroid cancer. However, the precise role of PBF in thyroid tumorigenesis is unclear. Here, we present extensive evidence demonstrating that PBF is a novel regulator of p53, a tumor suppressor protein with a key role in maintaining genetic stability, which is infrequently mutated in differentiated thyroid cancer. By coimmunoprecipitation and proximity-ligation assays, we show that PBF binds specifically to p53 in thyroid cells and significantly represses transactivation of responsive promoters. Further, we identify that PBF decreases p53 stability by enhancing ubiquitination, which appears dependent on the E3 ligase activity of Mdm2. Impaired p53 function was evident in a transgenic mouse model with thyroid-specific PBF overexpression (transgenic PBF mice), which had significantly increased genetic instability as indicated by fluorescent inter simple sequence repeat-PCR analysis. Consistent with this, approximately 40% of all DNA repair genes examined were repressed in transgenic PBF primary cultures, including genes with critical roles in maintaining genomic integrity such as Mgmt, Rad51, and Xrcc3. Our data also revealed that PBF induction resulted in up-regulation of the E2 enzyme Rad6 in murine thyrocytes and was associated with Rad6 expression in human thyroid tumors. Overall, this work provides novel insights into the role of the protooncogene PBF as a negative regulator of p53 function in thyroid tumorigenesis, in which PBF is generally overexpressed and p53 mutations are rare compared with other tumor types.


Assuntos
Proteínas de Transporte/metabolismo , Regulação da Expressão Gênica , Proteínas de Membrana/metabolismo , Glândula Tireoide/metabolismo , Proteína Supressora de Tumor p53/genética , Animais , Apoptose , Linhagem Celular Tumoral , Sobrevivência Celular , Transformação Celular Neoplásica/genética , Células Cultivadas , Reparo do DNA , Feminino , Genes Reporter , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Camundongos , Camundongos Transgênicos , Ligação Proteica , Neoplasias da Glândula Tireoide/genética , Neoplasias da Glândula Tireoide/metabolismo , Ubiquitina/química
5.
Stem Cells ; 30(7): 1338-48, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22674792

RESUMO

Y-box binding protein-1 (YB-1) is the first reported oncogenic transcription factor to induce the tumor-initiating cell (TIC) surface marker CD44 in triple-negative breast cancer (TNBC) cells. In order for CD44 to be induced, YB-1 must be phosphorylated at S102 by p90 ribosomal S6 kinase (RSK). We therefore questioned whether RSK might be a tractable molecular target to eliminate TICs. In support of this idea, injection of MDA-MB-231 cells expressing Flag-YB-1 into mice increased tumor growth as well as enhanced CD44 expression. Despite enrichment for TICs, these cells were sensitive to RSK inhibition when treated ex vivo with BI-D1870. Targeting RSK2 with small interfering RNA (siRNA) or small molecule RSK kinase inhibitors (SL0101 and BI-D1870) blocked TNBC monolayer cell growth by ∼100%. In a diverse panel of breast tumor cell line models RSK2 siRNA predominantly targeted models of TNBC. RSK2 inhibition decreased CD44 promoter activity, CD44 mRNA, protein expression, and mammosphere formation. CD44(+) cells had higher P-RSK(S221/227) , P-YB-1(S102) , and mitotic activity relative to CD44(-) cells. Importantly, RSK2 inhibition specifically suppressed the growth of TICs and triggered cell death. Moreover, silencing RSK2 delayed tumor initiation in mice. In patients, RSK2 mRNA was associated with poor disease-free survival in a cohort of 244 women with breast cancer that had not received adjuvant treatment, and its expression was highest in the basal-like breast cancer subtype. Taking this further, we report that P-RSK(S221/227) is present in primary TNBCs and correlates with P-YB-1(S102) as well as CD44. In conclusion, RSK2 inhibition provides a novel therapeutic avenue for TNBC and holds the promise of eliminating TICs.


Assuntos
Neoplasias da Mama/metabolismo , Proteínas Quinases S6 Ribossômicas 90-kDa/metabolismo , Proteína 1 de Ligação a Y-Box/metabolismo , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Benzopiranos/farmacologia , Western Blotting , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/terapia , Linhagem Celular Tumoral , Feminino , Citometria de Fluxo , Imunofluorescência , Humanos , Receptores de Hialuronatos/genética , Receptores de Hialuronatos/metabolismo , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Monossacarídeos/farmacologia , Regiões Promotoras Genéticas/genética , Pteridinas/farmacologia , Reação em Cadeia da Polimerase em Tempo Real , Proteínas Quinases S6 Ribossômicas 90-kDa/antagonistas & inibidores , Proteínas Quinases S6 Ribossômicas 90-kDa/genética , Proteína 1 de Ligação a Y-Box/genética
7.
Expert Rev Mol Med ; 12: e22, 2010 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-20653987

RESUMO

Tumour recurrence is one of the biggest challenges in breast cancer management because it affects 25-30% of women with breast cancer and the tumours are often incurable. Women with triple-negative breast cancer (TNBC--lacking expression of the oestrogen receptor, progesterone receptor and the receptor HER2/ERBB2) have the highest rates of early recurrence relative to other breast cancer subtypes. Early recurrence might be due to tumour-initiating cells (TICs), which are resistant to conventional therapies, can remain dormant and can subsequently give rise to secondary tumours. In breast cancer, TICs are identified by the cell-surface markers CD44+/CD24-/EpCAM+ and/or possess ALDH1 enzyme activity. This subpopulation has the ability to self-renew, grow as mammospheres and initiate tumour formation. Fuelling the problem of relapse is the fact that chemotherapy and radiation can induce or select for TICs; this was reported in preclinical models and more recently in women being treated for breast cancer. Thus, new therapeutic agents for TNBC are presently being sought to overcome this problem. Here we review the roles of receptor tyrosine kinases, signalling intermediates and transcription factors in sustaining the TIC subpopulation. Particular emphasis is placed on targeting these molecules in order to eliminate and/or prevent the induction of TICs and ultimately reduce the frequency of TNBC recurrence.


Assuntos
Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Receptor ErbB-2/metabolismo , Receptores de Estrogênio/metabolismo , Receptores de Progesterona/metabolismo , Feminino , Humanos , Modelos Biológicos
8.
Cancer Res ; 70(7): 2840-51, 2010 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-20332234

RESUMO

Y-box binding protein-1 (YB-1) is an oncogenic transcription/translation factor expressed in >40% of breast cancers, where it is associated with poor prognosis, disease recurrence, and drug resistance. We questioned whether this may be linked to the ability of YB-1 to induce the expression of genes linked to cancer stem cells such as CD44 and CD49f. Herein, we report that YB-1 binds the CD44 and CD49f promoters to transcriptionally upregulate their expressions. The introduction of wild-type (WT) YB-1 or activated P-YB-1(S102) stimulated the production of CD44 and CD49f in MDA-MB-231 and SUM 149 breast cancer cell lines. YB-1-transfected cells also bound to the CD44 ligand hyaluronan more than the control cells. Similarly, YB-1 was induced in immortalized breast epithelial cells and upregulated CD44. Conversely, silencing YB-1 decreased CD44 expression as well as reporter activity in SUM 149 cells. In mice, expression of YB-1 in the mammary gland induces CD44 and CD49f with associated hyperplasia. Further, activated mutant YB-1(S102D) enhances self-renewal, primary and secondary mammosphere growth, and soft-agar colony growth, which were reversible via loss of CD44 or CD49f. We next addressed the consequence of this system on therapeutic responsiveness. Here, we show that paclitaxel induces P-YB-1(S102) expression, nuclear localization of activated YB-1, and CD44 expression. The overexpression of WT YB-1 promotes mammosphere growth in the presence of paclitaxel. Importantly, targeting YB-1 sensitized the CD44(High)/CD24(Low) cells to paclitaxel. In conclusion, YB-1 promotes cancer cell growth and drug resistance through its induction of CD44 and CD49f.


Assuntos
Neoplasias da Mama/metabolismo , Proteínas de Ligação a DNA/metabolismo , Receptores de Hialuronatos/biossíntese , Integrina alfa6/biossíntese , Proteínas Nucleares/metabolismo , Animais , Antineoplásicos Fitogênicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Processos de Crescimento Celular/genética , Linhagem Celular Tumoral , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Proteínas de Ligação a DNA/genética , Resistencia a Medicamentos Antineoplásicos , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Receptores de Hialuronatos/genética , Integrina alfa6/genética , Camundongos , Camundongos Transgênicos , Proteínas Nucleares/genética , Paclitaxel/farmacologia , Proteína 1 de Ligação a Y-Box
9.
Cancer Res ; 68(24): 10238-46, 2008 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-19074892

RESUMO

Drugs that target the insulin-like growth factor-I receptor (IGF-IR) and/or insulin receptor (IR) are currently under investigation for a variety of malignancies including breast cancer. Although we have previously reported that IGF-IR expression in primary breast tumors is common, the activation status of this receptor has not been examined in relation to survival. Phosphorylated IGF-IR/IR (P-IGF-IR/IR) and its downstream signaling partner phospho-S6 (P-S6) were evaluated immunohistochemically in tumor tissue microarrays representing 438 cases of invasive breast cancer. P-IGF-IR/IR (n = 114; P = 0.046) and total levels of IR (n = 122; P = 0.009) were indicative of poor survival, whereas total IGF-IR (n = 112; P = 0.304) was not. P-IGF-IR/IR and P-S6 were coordinately expressed in primary breast tumors (likelihood ratio, 11.57; P = 6.70 x 10(-4)). Importantly, P-IGF-IR/IR was detected in all breast cancer subtypes (luminal, 48.1%; triple negative, 41.9%; and HER2, 64.3%). In vitro, the IGF-IR/IR inhibitor BMS-536924 decreased phospho-RSK and P-S6, and significantly suppressed the growth of breast cancer cell lines MCF-7, SUM149, and AU565 representing the luminal, triple negative, and HER2 subtypes, respectively, in monolayer and soft agar. BMS-536924 also inhibited growth in tamoxifen resistant MCF-7 Tam-R cells while having little effect on immortalized normal breast epithelial cells. Thus, we can determine which patients have the activated receptor and provide evidence that P-IGF-IR/IR is a prognostic factor for breast cancer. Beyond this, P-IGF-IR/IR could be a predictive marker for response to IGF-IR and/or IR-targeted therapies, as these inhibitors may be of benefit in all breast cancer subtypes including those with acquired resistance to tamoxifen.


Assuntos
Neoplasias da Mama/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Receptor IGF Tipo 1/metabolismo , Receptor de Insulina/metabolismo , Benzimidazóis/farmacologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Processos de Crescimento Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Humanos , Fosforilação , Piridonas/farmacologia
10.
Breast Cancer Res ; 10(6): R99, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-19036157

RESUMO

INTRODUCTION: Basal-like breast cancers (BLBC) frequently overexpress the epidermal growth factor receptor (EGFR) and subsequently have high levels of signaling through the MAP kinase pathway, which is thought to contribute to their aggressive behavior. While we have previously reported the expression of Y-box binding protein-1 (YB-1) in 73% of BLBC, it is unclear whether it can be regulated by a component of the MAP kinase signaling pathway. Phosphorylation of YB-1 at the serine 102 residue is required for transcriptional activation of growth-enhancing genes, such as EGFR. Using Motifscan we identified p90 ribosomal S6 kinase (RSK) as a potential candidate for activating YB-1. METHODS: Inhibition of RSK1 and RSK2 was achieved using siRNA and the small molecule SL0101. RSK1, RSK2, activated RSK and kinase-dead RSK were expressed in HCC1937 cells. Kinase assays were performed to illustrate direct phosphorylation of YB-1 by RSK. The impact of inhibiting RSK on YB-1 function was measured by luciferase assays and chromatin immunoprecipitation. RESULTS: Using an in vitro kinase assay, RSK1 and RSK2 were shown to directly phosphorylate YB-1. Interestingly, they were more effective activators of YB-1 than AKT or another novel YB-1 kinase, PKC alpha. Phosphorylation of YB-1 (serine 102 residue) is blocked by inhibition of the MAP kinase pathway or by perturbing RSK1/RSK2 with siRNA or SL0101. In immortalized breast epithelial cells where RSK is active yet AKT is not, YB-1 is phosphorylated. Supporting this observation, RSK2-/- mouse embryo fibroblasts lose the ability to phosphorylate YB-1 in response to epidermal growth factor. This subsequently interfered with the ability of YB-1 to regulate the expression of EGFR. The RSK inhibitor SL0101 decreased the ability of YB-1 to bind the promoter, transactivate and ultimately reduce EGFR expression. In concordance with these results the expression of constitutively active RSK1 increased YB-1 phosphorylation, yet the kinase-dead RSK did not. CONCLUSIONS: We therefore conclude that RSK1/RSK2 are novel activators of YB-1, able to phosphorylate the serine 102 residue. This provides a newly described mechanism whereby YB-1 is activated in breast cancer. This implicates the EGFR/RSK/YB-1 pathway as an important component of BLBC, providing an important opportunity for therapeutic intervention.


Assuntos
Neoplasias da Mama/metabolismo , Neoplasia de Células Basais/metabolismo , Proteínas Quinases S6 Ribossômicas 90-kDa/metabolismo , Proteína 1 de Ligação a Y-Box/metabolismo , Animais , Benzopiranos/farmacologia , Western Blotting , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Imunoprecipitação da Cromatina , Ensaio de Desvio de Mobilidade Eletroforética , Embrião de Mamíferos/citologia , Embrião de Mamíferos/efeitos dos fármacos , Embrião de Mamíferos/metabolismo , Receptores ErbB/metabolismo , Feminino , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Imunoprecipitação , Luciferases/metabolismo , Sistema de Sinalização das MAP Quinases , Camundongos , Monossacarídeos/farmacologia , Neoplasia de Células Basais/genética , Neoplasia de Células Basais/patologia , Fosforilação/efeitos dos fármacos , Regiões Promotoras Genéticas , Proteína Quinase C-alfa/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Interferente Pequeno/farmacologia , Proteínas Quinases S6 Ribossômicas 90-kDa/antagonistas & inibidores , Proteínas Quinases S6 Ribossômicas 90-kDa/genética , Serina/química , Serina/metabolismo , Proteína 1 de Ligação a Y-Box/genética
11.
Breast Cancer Res ; 9(5): R61, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17875215

RESUMO

INTRODUCTION: Basal-like breast cancers (BLBCs) are very aggressive, and present serious clinical challenges as there are currently no targeted therapies available. We determined the regulatory role of Y-box binding protein-1 (YB-1) on epidermal growth factor receptor (EGFR) overexpression in BLBC, and the therapeutic potential of inhibiting EGFR. We pursued this in light of our recent work showing that YB-1 induces the expression of EGFR, a new BLBC marker. METHODS: Primary tumour tissues were evaluated for YB1 protein expression by immunostaining tissue microarrays, while copy number changes were assessed by comparative genomic hybridization (CGH). The ability of YB-1 to regulate EGFR was evaluated using luciferase reporter, chromatin immunoprecipitation (ChIP) and gel shift assays. The impact of Iressa on monolayer cell growth was measured using an ArrayScan VTI high-throughput analyser to count cell number, and colony formation in soft agar was used to measure anchorage-independent growth. RESULTS: YB-1 (27/37 or 73% of cases, P = 3.899 x 10(-4)) and EGFR (20/37 or 57.1% of cases, P = 9.206 x 10(-12)) are expressed in most cases of BLBC. However, they are not typically amplified in primary BLBC, suggesting overexpression owing to transcriptional activation. In support of this, we demonstrate that YB-1 promotes EGFR reporter activity. YB-1 specifically binds the EGFR promoter at two different YB-1-responsive elements (YREs) located at -940 and -968 using ChIP and gel shift assays in a manner that is dependent on the phosphorylation of S102 on YB-1. Inhibiting EGFR with Iressa suppressed the growth of SUM149 cells by approximately 40% in monolayer, independent of mutations in the receptor. More importantly anchorage-independent growth of BLBC cell lines was inhibited with combinations of Iressa and YB-1 suppression. CONCLUSION: We have identified for the first time a causal link for the expression of EGFR in BLBC through the induction by YB-1 where it binds specifically to two distinguished YREs. Finally, inhibition of EGFR in combination with suppression of YB-1 presents a potential opportunity for therapy in BLBC.


Assuntos
Antineoplásicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Receptores ErbB/genética , Regulação Neoplásica da Expressão Gênica , Quinazolinas/farmacologia , Proteína 1 de Ligação a Y-Box/farmacologia , Diferenciação Celular , Linhagem Celular Tumoral/efeitos dos fármacos , Linhagem Celular Tumoral/metabolismo , Proliferação de Células , Imunoprecipitação da Cromatina , Ensaio de Desvio de Mobilidade Eletroforética , Receptores ErbB/antagonistas & inibidores , Receptores ErbB/metabolismo , Feminino , Gefitinibe , Humanos , Luciferases/metabolismo , Hibridização de Ácido Nucleico , Fosforilação , Receptor ErbB-2/metabolismo , Análise Serial de Tecidos
12.
Transl Oncogenomics ; 2: 49-65, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-23641145

RESUMO

The Y-box Binding Protein-1 (YB-1) is a highly conserved oncogenic transcription/translation factor that is expressed in cancers affecting adults and children. It is now believed that YB-1 plays a causal role in the development of cancer given recent work showing that its expression drives the tumorigenesis in the mammary gland. In human breast cancers, YB-1 is associated with rapidly proliferating tumors that are highly aggressive. Moreover, expression of YB-1 promotes the growth of breast cancer cell lines both in monolayer and anchorage independent conditions. The involvement of YB-1 in breast cancer pathogenesis has made it a putative therapeutic target; however, the mechanism(s) that regulate YB-1 are poorly understood. This review first describes the oncogenic properties of YB-1 in cancer. It also highlights the importance of YB-1 in hardwiring signal transduction pathways to the regulation of genes involved in the development of cancer.

13.
J Clin Endocrinol Metab ; 90(7): 4341-9, 2005 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-15886233

RESUMO

CONTEXT: There are currently no clear markers for the detection of differentiated thyroid cancer and its recurrence. Pituitary tumor transforming gene (PTTG) is a protooncogene implicated in the pathogenesis of multiple tumor types, which stimulates fibroblast growth factor-2 secretion via PTTG binding factor (PBF). OBJECTIVE: The aim of this study was to ascertain whether PBF expression is associated with thyroid cancer outcome. DESIGN: PBF expression was measured at the mRNA and protein level. Tissue was collected during surgery, with normal samples being taken from the contralateral lobe. In vitro studies ascertained the ability of PBF to transform cells and form tumors in nude mice and its subcellular localization. SETTING: The study was conducted at a primary care/referral center. PATIENTS: Thyroid tumors were collected from a series of 27 patients undergoing surgical excision of papillary and follicular thyroid tumors. INTERVENTION: No intervention was conducted. MAIN OUTCOME MEASURE: The expression of PBF in thyroid cancers compared with normal thyroid, hypothesized before the investigation to be raised in tumors, was the main outcome measure. RESULTS: PBF mRNA expression was higher in differentiated thyroid carcinomas than in normal thyroid (P < 0.001; n = 27) and was independently associated with tumor recurrence (P = 0.002; R(2) = 0.49). PTTG was able to up-regulate PBF mRNA expression in vitro (P < 0.001; n = 12), and stable overexpression of PBF in NIH3T3 cells resulted in significant colony formation (P < 0.001; n = 12). In vivo, stable sc overexpression of PBF induced tumor formation in athymic nude mice. CONCLUSIONS: PBF is an additional prognostic indicator in differentiated thyroid cancer that is transforming in vitro and tumorigenic in vivo.


Assuntos
Transformação Celular Neoplásica , Proteínas de Membrana/genética , Neoplasias da Glândula Tireoide/genética , Adulto , Idoso , Animais , Feminino , Células HCT116 , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Proteínas de Membrana/análise , Camundongos , Camundongos Nus , Pessoa de Meia-Idade , Células NIH 3T3 , Proteínas de Neoplasias/análise , Proteínas de Neoplasias/fisiologia , Recidiva Local de Neoplasia , RNA Mensageiro/análise , Securina , Neoplasias da Glândula Tireoide/química , Neoplasias da Glândula Tireoide/patologia
14.
Oncogene ; 24(30): 4861-6, 2005 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-15897900

RESUMO

Cancer reflects the progressive accumulation of genetic alterations and subsequent genetic instability of cells. Cytogenetic studies have demonstrated the importance of aneuploidy in differentiated thyroid cancer development. The pituitary tumour transforming gene (PTTG), also known as securin, is a mitotic checkpoint protein which inhibits sister chromatid separation during mitosis. PTTG is highly expressed in many cancers and overexpression of PTTG induces aneuploidy in vitro. Using fluorescent intersimple sequence repeat PCR (FISSR-PCR), we investigated the relationship between PTTG expression and the degree of genetic instability in normal and tumorous thyroid samples. The genomic instability index (GI index) was 6.7-72.7% higher in cancers than normal thyroid tissues. Follicular thyroid tumours exhibited greater genetic instability than papillary tumours (27.6% (n=9) versus 14.5% (n=10), P=0.03). We also demonstrated a strong relationship between PTTG expression and the degree of genetic instability in thyroid cancers (R2=0.80, P=0.007). To further investigate PTTG's role in genetic instability, we transfected FTC133 thyroid follicular cells and observed increased genetic instability in cells overexpressing PTTG compared with vector-only-transfected controls (n=3, GI Index VO=29.7+/-5.2 versus PTTG=63.7+/-6.4, P=0.013). Further, we observed a dose response in genetic instability and PTTG expression (GI Index low dose (0.5 microg DNA/ six-well plate) PTTG=15.3%+/-1.7 versus high dose (3 microg DNA) PTTG=50.8%+/-3.3, P=0.006). Overall, we describe the first use of FISSR-PCR in human cancers, and demonstrate that PTTG expression correlates with genetic instability in vivo, and induces genetic instability in vitro. We conclude that PTTG may be an important gene in the mutator phenotype development in thyroid cancer.


Assuntos
Instabilidade Genômica , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Glândula Tireoide/metabolismo , Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/genética , Caspase 3 , Caspase 7 , Caspases/metabolismo , Linhagem Celular , Humanos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Securina , Neoplasias da Glândula Tireoide/patologia
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