RESUMEN
Connections between epigenetic reprogramming and transcription or splicing create novel mechanistic networks that can be targeted with tailored therapies. Multiple subunits of the chromatin remodeling BAF complex, including ARID1A, play a role in oncogenesis, either as tumor suppressors or oncogenes. Recent work demonstrated that EWS-FLI1, the oncogenic driver of Ewing sarcoma (ES), plays a role in chromatin regulation through interactions with the BAF complex. However, the specific BAF subunits that interact with EWS-FLI1 and the precise role of the BAF complex in ES oncogenesis remain unknown. In addition to regulating transcription, EWS-FLI1 also alters the splicing of many mRNA isoforms, but the role of splicing modulation in ES oncogenesis is not well understood. We have identified a direct connection between the EWS-FLI1 protein and ARID1A isoform protein variant ARID1A-L. We demonstrate here that ARID1A-L is critical for ES maintenance and supports oncogenic transformation. We further report a novel feed-forward cycle in which EWS-FLI1 leads to preferential splicing of ARID1A-L, promoting ES growth, and ARID1A-L reciprocally promotes EWS-FLI1 protein stability. Dissecting this interaction may lead to improved cancer-specific drug targeting.
Asunto(s)
Carcinogénesis/genética , Proteínas Nucleares/genética , Proteínas de Fusión Oncogénica/genética , Proteína Proto-Oncogénica c-fli-1/genética , Proteína EWS de Unión a ARN/genética , Sarcoma de Ewing/genética , Factores de Transcripción/genética , Empalme Alternativo/genética , Línea Celular Tumoral , Ensamble y Desensamble de Cromatina/genética , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/genética , Epigénesis Genética/genética , Regulación Neoplásica de la Expresión Génica , Humanos , Proteínas Nucleares/química , Proteínas de Fusión Oncogénica/química , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Estabilidad Proteica , Proteína Proto-Oncogénica c-fli-1/química , Proteína EWS de Unión a ARN/química , Sarcoma de Ewing/patología , Factores de Transcripción/químicaRESUMEN
Cell cycle progression is orchestrated by E2F factors. We previously reported that in ETS-driven cancers of the bone and prostate, activating E2F3 cooperates with ETS on target promoters. The mechanism of target co-regulation remained unknown. Using RNAi and time-resolved chromatin-immunoprecipitation in Ewing sarcoma we report replacement of E2F3/pRB by constitutively expressed repressive E2F4/p130 complexes on target genes upon EWS-FLI1 modulation. Using mathematical modeling we interrogated four alternative explanatory models for the observed EWS-FLI1/E2F3 cooperation based on longitudinal E2F target and regulating transcription factor expression analysis. Bayesian model selection revealed the formation of a synergistic complex between EWS-FLI1 and E2F3 as the by far most likely mechanism explaining the observed kinetics of E2F target induction. Consequently we propose that aberrant cell cycle activation in Ewing sarcoma is due to the de-repression of E2F targets as a consequence of transcriptional induction and physical recruitment of E2F3 by EWS-FLI1 replacing E2F4 on their target promoters.
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Factor de Transcripción E2F3/metabolismo , Factor de Transcripción E2F4/metabolismo , Regulación Neoplásica de la Expresión Génica , Proteínas de Fusión Oncogénica/metabolismo , Proteína Proto-Oncogénica c-fli-1/metabolismo , Proteína EWS de Unión a ARN/metabolismo , Algoritmos , Teorema de Bayes , Ciclo Celular/genética , Línea Celular Tumoral , Inmunoprecipitación de Cromatina , Factor de Transcripción E2F3/genética , Factor de Transcripción E2F4/genética , Humanos , Immunoblotting , Modelos Genéticos , Proteínas de Fusión Oncogénica/genética , Regiones Promotoras Genéticas/genética , Unión Proteica , Proteína Proto-Oncogénica c-fli-1/genética , Interferencia de ARN , Proteína EWS de Unión a ARN/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Sarcoma de Ewing/genética , Sarcoma de Ewing/metabolismo , Sarcoma de Ewing/patologíaRESUMEN
Deregulated E2F transcription factor activity occurs in the vast majority of human tumors and has been solidly implicated in disturbances of cell cycle control, proliferation, and apoptosis. Aberrant E2F regulatory activity is often caused by impairment of control through pRB function, but little is known about the interplay of other oncoproteins with E2F. Here we show that ETS transcription factor fusions resulting from disease driving rearrangements in Ewing sarcoma (ES) and prostate cancer (PC) are one such class of oncoproteins. We performed an integrative study of genome-wide DNA-binding and transcription data in EWSR1/FLI1 expressing ES and TMPRSS2/ERG containing PC cells. Supported by promoter activity and mutation analyses, we demonstrate that a large fraction of E2F3 target genes are synergistically coregulated by these aberrant ETS proteins. We propose that the oncogenic effect of ETS fusion oncoproteins is in part mediated by the disruptive effect of the E2F-ETS interaction on cell cycle control. Additionally, a detailed analysis of the regulatory targets of the characteristic EWSR1/FLI1 fusion in ES identifies two functionally distinct gene sets. While synergistic regulation in concert with E2F in the promoter of target genes has a generally activating effect, EWSR1/FLI1 binding independent of E2F3 is predominantly associated with repressed differentiation genes. Thus, EWSR1/FLI1 appears to promote oncogenesis by simultaneously promoting cell proliferation and perturbing differentiation.
Asunto(s)
Factor de Transcripción E2F3/genética , Regulación Neoplásica de la Expresión Génica , Proteínas de Fusión Oncogénica/metabolismo , Neoplasias de la Próstata/genética , Proteína Proto-Oncogénica c-fli-1/metabolismo , Proteína EWS de Unión a ARN/metabolismo , Sarcoma de Ewing/genética , Apoptosis/genética , Ciclo Celular/genética , Diferenciación Celular/genética , Línea Celular Tumoral , Proliferación Celular , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Factor de Transcripción E2F3/metabolismo , Humanos , Masculino , Análisis de Secuencia por Matrices de Oligonucleótidos , Proteínas de Fusión Oncogénica/genética , Regiones Promotoras Genéticas , Neoplasias de la Próstata/patología , Unión Proteica , Proteína Proto-Oncogénica c-fli-1/genética , Proteína EWS de Unión a ARN/genética , Sarcoma de Ewing/patología , Serina Endopeptidasas/genética , Serina Endopeptidasas/metabolismo , Transactivadores/genética , Transactivadores/metabolismo , Regulador Transcripcional ERGRESUMEN
Langerhans cell histiocytosis (LCH) is an enigmatic disease defined by the accumulation of Langerhans cell-like dendritic cells (DCs). In the present study, we demonstrate that LCH cells exhibit a unique transcription profile that separates them not only from plasmacytoid and myeloid DCs, but also from epidermal Langerhans cells, indicating a distinct DC entity. Molecular analysis revealed that isolated and tissue-bound LCH cells selectively express the Notch ligand Jagged 2 (JAG2) and are the only DCs that express both Notch ligand and its receptor. We further show that JAG2 signaling induces key LCH-cell markers in monocyte-derived DCs, suggesting a functional role of Notch signaling in LCH ontogenesis. JAG2 also induced matrix-metalloproteinases 1 and 12, which are highly expressed in LCH and may account for tissue destruction in LCH lesions. This induction was selective for DCs and was not recapitulated in monocytes. The results of the present study suggest that JAG2-mediated Notch activation confers phenotypic and functional aspects of LCH to DCs; therefore, interference with Notch signaling may be an attractive strategy to combat this disease.
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Células Dendríticas/patología , Histiocitosis de Células de Langerhans/genética , Receptor Notch1/fisiología , Adolescente , Diferenciación Celular/fisiología , Células Cultivadas , Niño , Preescolar , Células Dendríticas/metabolismo , Femenino , Histiocitosis de Células de Langerhans/metabolismo , Histiocitosis de Células de Langerhans/patología , Humanos , Lactante , Péptidos y Proteínas de Señalización Intercelular/genética , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Proteína Jagged-2 , Células de Langerhans/citología , Células de Langerhans/metabolismo , Células de Langerhans/patología , Masculino , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Receptor Notch1/genética , Receptor Notch1/metabolismo , TranscriptomaRESUMEN
Ewing sarcoma is a pediatric bone and soft tissue cancer with an urgent need for new therapies to improve disease outcome. To identify effective drugs, phenotypic drug screening has proven to be a powerful method, but achievable throughput in mouse xenografts, the preclinical Ewing sarcoma standard model, is limited. Here, we explored the use of xenografts in zebrafish for high-throughput drug screening to discover new combination therapies for Ewing sarcoma. We subjected xenografts in zebrafish larvae to high-content imaging and subsequent automated tumor size analysis to screen single agents and compound combinations. We identified three drug combinations effective against Ewing sarcoma cells: Irinotecan combined with either an MCL-1 or an BCL-XL inhibitor and in particular dual inhibition of the anti-apoptotic proteins MCL-1 and BCL-XL, which efficiently eradicated tumor cells in zebrafish xenografts. We confirmed enhanced efficacy of dual MCL-1/BCL-XL inhibition compared to single agents in a mouse PDX model. In conclusion, high-content screening of small compounds on Ewing sarcoma zebrafish xenografts identified dual MCL-1/BCL-XL targeting as a specific vulnerability and promising therapeutic strategy for Ewing sarcoma, which warrants further investigation towards clinical application.
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Sarcoma de Ewing , Humanos , Animales , Ratones , Sarcoma de Ewing/tratamiento farmacológico , Sarcoma de Ewing/genética , Sarcoma de Ewing/metabolismo , Pez Cebra/metabolismo , Proteína 1 de la Secuencia de Leucemia de Células Mieloides/genética , Proteína 1 de la Secuencia de Leucemia de Células Mieloides/metabolismo , Evaluación Preclínica de Medicamentos , Xenoinjertos , Apoptosis , Proteína bcl-X/genética , Proteína bcl-X/metabolismo , Línea Celular TumoralRESUMEN
Notch can act as an oncogene or as a tumour suppressor and thus can either promote or inhibit tumour cell growth. To establish Notch status in Ewing's sarcoma family of tumours (ESFT), we investigated the Notch pathway by gene expression profiling meta-analysis or immunohistochemistry in samples obtained from 96 and 24 ESFT patients, respectively. We found that although Notch receptors were highly expressed, Notch did not appear to be active, as evidenced by the absence of Notch receptors in cell nuclei. In contrast, we show that Notch receptors known to be active in colon adenocarcinoma, hepatocarcinoma, and pancreatic carcinoma stain cell nuclei in these tumours. High expression of the Notch effector HES1 transcription factor, usually used as a surrogate marker for active Notch, was also restricted to outside of the nucleus in the majority of ESFT, and analysis of HES1 gene targets indicated HES1 to be transcriptionally inactive. Neither forced activation nor pharmacological or genetic blocking of Notch affected HES1 expression in ESFT cells, indicating HES1 expression to be uncoupled from the Notch pathway. Additional functional studies in ESFT cell lines confirmed Notch to be switched off. Finally, unlike experiments in which HES1 expression was modulated, experimental activation of Notch in ESFT cell lines via several means blocked cell proliferation and reduced their clonogenic potential in soft agar. These indicate that HES1 is uncoupled from Notch in ESFT, that EWS-FLI1-mediated inhibition of Notch contributes to ESFT aggressive cell growth, and support a role for Notch in ESFT tumour suppression, at least partly through the Notch effector HEY1.
Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Neoplasias Óseas/metabolismo , Proteínas de Homeodominio/metabolismo , Receptores Notch/metabolismo , Sarcoma de Ewing/metabolismo , Neoplasias Óseas/genética , Neoplasias Óseas/patología , Núcleo Celular/metabolismo , Proliferación Celular , Perfilación de la Expresión Génica/métodos , Regulación Neoplásica de la Expresión Génica , Humanos , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Células Madre Neoplásicas/patología , Receptores Notch/genética , Sarcoma de Ewing/genética , Sarcoma de Ewing/patología , Transducción de Señal/fisiología , Factor de Transcripción HES-1 , Células Tumorales CultivadasRESUMEN
Ewing tumors (ET) are highly malignant, localized in bone or soft tissue, and are molecularly defined by ews/ets translocations. DNA microarray analysis revealed a relationship of ET to both endothelium and fetal neural crest. We identified expression of histone methyltransferase enhancer of Zeste, Drosophila, Homolog 2 (EZH2) to be increased in ET. Suppressive activity of EZH2 maintains stemness in normal and malignant cells. Here, we found EWS/FLI1 bound to the EZH2 promoter in vivo, and induced EZH2 expression in ET and mesenchymal stem cells. Down-regulation of EZH2 by RNA interference in ET suppressed oncogenic transformation by inhibiting clonogenicity in vitro. Similarly, tumor development and metastasis was suppressed in immunodeficient Rag2(-/-)gamma(C)(-/-) mice. EZH2-mediated gene silencing was shown to be dependent on histone deacetylase (HDAC) activity. Subsequent microarray analysis of EZH2 knock down, HDAC-inhibitor treatment and confirmation in independent assays revealed an undifferentiated phenotype maintained by EZH2 in ET. EZH2 regulated stemness genes such as nerve growth factor receptor (NGFR), as well as genes involved in neuroectodermal and endothelial differentiation (EMP1, EPHB2, GFAP, and GAP43). These data suggest that EZH2 might have a central role in ET pathology by shaping the oncogenicity and stem cell phenotype of this tumor.
Asunto(s)
Proteínas de Unión al ADN/fisiología , Células Endoteliales/patología , Placa Neural/patología , Sarcoma de Ewing/etiología , Factores de Transcripción/fisiología , Animales , Diferenciación Celular , Línea Celular Tumoral , Proliferación Celular , Proteína Potenciadora del Homólogo Zeste 2 , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Silenciador del Gen , Histona Desacetilasas , Humanos , Células Madre Mesenquimatosas , Ratones , Metástasis de la Neoplasia , Proteínas de Fusión Oncogénica , Complejo Represivo Polycomb 2 , Proteína Proto-Oncogénica c-fli-1 , Proteína EWS de Unión a ARN , Sarcoma de Ewing/patologíaRESUMEN
Ewing sarcoma (ES) is a rare aggressive cancer of bone and soft tissue that is mainly characterized by a reciprocal chromosomal translocation. As a result, about 90% of cases express the EWS-FLI1 fusion protein that has been shown to function as an aberrant transcription factor driving sarcomagenesis. ES is the second most common malignant bone tumor in children and young adults. Current treatment modalities include dose-intensified chemo- and radiotherapy, as well as surgery. Despite these strategies, patients who present with metastasis or relapse still have dismal prognosis, warranting a better understanding of treatment resistant-disease biology in order to generate better prognostic and therapeutic tools. Since the genomes of ES tumors are relatively quiet and stable, exploring the contributions of epigenetic mechanisms in the initiation and progression of the disease becomes inevitable. The search for novel biomarkers and potential therapeutic targets of cancer metastasis and chemotherapeutic drug resistance is increasingly focusing on long non-coding RNAs (lncRNAs). Recent advances in genome analysis by high throughput sequencing have immensely expanded and advanced our knowledge of lncRNAs. They are non-protein coding RNA species with multiple biological functions that have been shown to be dysregulated in many diseases and are emerging as crucial players in cancer development. Understanding the various roles of lncRNAs in tumorigenesis and metastasis would determine eclectic avenues to establish therapeutic and diagnostic targets. In ES, some lncRNAs have been implicated in cell proliferation, migration and invasion, features that make them suitable as relevant biomarkers and therapeutic targets. In this review, we comprehensively discuss known lncRNAs implicated in ES that could serve as potential biomarkers and therapeutic targets of the disease. Though some current reviews have discussed non-coding RNAs in ES, to our knowledge, this is the first review focusing exclusively on ES-associated lncRNAs.
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Neoplasias Óseas , ARN Largo no Codificante , Sarcoma de Ewing , Neoplasias Óseas/genética , Neoplasias Óseas/patología , Niño , Epigénesis Genética , Humanos , Recurrencia Local de Neoplasia/genética , ARN Largo no Codificante/genética , Sarcoma de Ewing/genética , Sarcoma de Ewing/patología , Adulto JovenRESUMEN
The advent of dose intensified interval compressed therapy has improved event-free survival for patients with localized Ewing sarcoma (EwS) to 78% at 5 years. However, nearly a quarter of patients with localized tumors and 60-80% of patients with metastatic tumors suffer relapse and die of disease. In addition, those who survive are often left with debilitating late effects. Clinical features aside from stage have proven inadequate to meaningfully classify patients for risk-stratified therapy. Therefore, there is a critical need to develop approaches to risk stratify patients with EwS based on molecular features. Over the past decade, new technology has enabled the study of multiple molecular biomarkers in EwS. Preliminary evidence requiring validation supports copy number changes, and loss of function mutations in tumor suppressor genes as biomarkers of outcome in EwS. Initial studies of circulating tumor DNA demonstrated that diagnostic ctDNA burden and ctDNA clearance during induction are also associated with outcome. In addition, fusion partner should be a pre-requisite for enrollment on EwS clinical trials, and the fusion type and structure require further study to determine prognostic impact. These emerging biomarkers represent a new horizon in our understanding of disease risk and will enable future efforts to develop risk-adapted treatment.
RESUMEN
FUS, EWS, and TAF15 form the FET family of RNA-binding proteins whose genes are found rearranged with various transcription factor genes predominantly in sarcomas and in rare hematopoietic and epithelial cancers. The resulting fusion gene products have attracted considerable interest as diagnostic and promising therapeutic targets. So far, oncogenic FET fusion proteins have been regarded as strong transcription factors that aberrantly activate or repress target genes of their DNA-binding fusion partners. However, the role of the transactivating domain in the context of the normal FET proteins is poorly defined, and, therefore, our knowledge on how FET aberrations impact on tumor biology is incomplete. Since we believe that a full understanding of aberrant FET protein function can only arise from looking at both sides of the coin, the good and the evil, this paper summarizes evidence for the central function of FET proteins in bridging RNA transcription, processing, transport, and DNA repair.
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Bone and bone marrow are among the most frequent metastatic sites of cancer. The occurrence of bone metastasis is frequently associated with a dismal disease outcome. The prevention and therapy of bone metastases is a priority in the treatment of cancer patients. However, current therapeutic options for patients with bone metastatic disease are limited in efficacy and associated with increased morbidity. Therefore, most current therapies are mainly palliative in nature. A better understanding of the underlying molecular pathways of the bone metastatic process is warranted to develop novel, well-tolerated and more successful treatments for a significant improvement of patients' quality of life and disease outcome. In this review, we provide comparative mechanistic insights into the bone metastatic process of various solid tumors, including pediatric cancers. We also highlight current and innovative approaches to biologically targeted therapy and immunotherapy. In particular, we discuss the role of the bone marrow microenvironment in the attraction, homing, dormancy and outgrowth of metastatic tumor cells and the ensuing therapeutic implications. Multiple signaling pathways have been described to contribute to metastatic spread to the bone of specific cancer entities, with most knowledge derived from the study of breast and prostate cancer. However, it is likely that similar mechanisms are involved in different types of cancer, including multiple myeloma, primary bone sarcomas and neuroblastoma. The metastatic rate-limiting interaction of tumor cells with the various cellular and noncellular components of the bone-marrow niche provides attractive therapeutic targets, which are already partially exploited by novel promising immunotherapies.
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Neoplasias Óseas/diagnóstico , Neoplasias Óseas/secundario , Animales , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Neoplasias Óseas/terapia , Transición Epitelial-Mesenquimal , Humanos , Inmunoterapia , Modelos Biológicos , Microambiente TumoralRESUMEN
Results of immunotherapy in childhood solid cancer have been so far, with the exception of neuroblastoma, quite disappointing. Lack of knowledge of the immune contexture of these tumors may have contributed to the failure of immunotherapies so far. Here, we systematically reviewed the literature regarding the immunology of Wilms tumor (WT), one of the most frequent pediatric solid tumors of the abdomen. In Wilms tumor patients the high cure rate of >90%, achieved by the combination of surgery and radio-chemotherapy, is at the expense of a high early and late toxicity. Moreover, treatment-resistant entities, such as diffuse anaplastic tumors or recurrent disease, still pose unsolved clinical problems. Successful immunotherapy could represent a novel and possibly less-toxic treatment option. Employing the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) method of literature search, we analyzed the current knowledge of the immunological landscape of Wilms tumors in terms of tumor microenvironment, prognostic implications of single biomarkers, and immunotherapy response.
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Ewing sarcoma, a highly aggressive bone and soft-tissue cancer, is considered a prime example of the paradigms of a translocation-positive sarcoma: a genetically rather simple disease with a specific and neomorphic-potential therapeutic target, whose oncogenic role was irrefutably defined decades ago. This is a disease that by definition has micrometastatic disease at diagnosis and a dismal prognosis for patients with macrometastatic or recurrent disease. International collaborations have defined the current standard of care in prospective studies, delivering multiple cycles of systemic therapy combined with local treatment; both are associated with significant morbidity that may result in strong psychological and physical burden for survivors. Nevertheless, the combination of non-directed chemotherapeutics and ever-evolving local modalities nowadays achieve a realistic chance of cure for the majority of patients with Ewing sarcoma. In this review, we focus on the current standard of diagnosis and treatment while attempting to answer some of the most pressing questions in clinical practice. In addition, this review provides scientific answers to clinical phenomena and occasionally defines the resulting translational studies needed to overcome the hurdle of treatment-associated morbidities and, most importantly, non-survival.
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Ewing sarcoma (EwS) is a highly metastatic bone cancer characterized by the ETS fusion oncoprotein EWS-FLI1. EwS cells are phenotypically highly plastic and switch between functionally distinct cell states dependent on EWS-FLI1 fluctuations. Whereas EWS-FLI1high cells proliferate, EWS-FLI1low cells are migratory and invasive. Recently, we reported activation of MRTFB and TEAD, effectors of RhoA and Hippo signalling, upon low EWS-FLI1, orchestrating key steps of the EwS migratory gene expression program. TEAD and its co-activators YAP and TAZ are commonly overexpressed in cancer, providing attractive therapeutic targets. We find TAZ levels to increase in the migratory EWS-FLI1low state and to associate with adverse prognosis in EwS patients. We tested the effects of the potent YAP/TAZ/TEAD complex inhibitor verteporfin on EwS cell migration in vitro and on metastasis in vivo. Verteporfin suppressed expression of EWS-FLI1 regulated cytoskeletal genes involved in actin signalling to the extracellular matrix, effectively blocked F-actin and focal-adhesion assembly and inhibited EwS cell migration at submicromolar concentrations. In a mouse EwS xenograft model, verteporfin treatment reduced relapses at the surgical site and delayed lung metastasis. These data suggest that YAP/TAZ pathway inhibition may prevent EwS cell dissemination and metastasis, justifying further preclinical development of YAP/TAZ inhibitors for EwS treatment.
RESUMEN
BACKGROUND: Some human cancers demonstrate cellular hierarchies in which tumor-initiating cancer stem cells generate progeny cells with reduced tumorigenic potential. This cancer stem cell population is proposed to be a source of therapy-resistant and recurrent disease. Ewing sarcoma family tumors (ESFT) are highly aggressive cancers in which drug-resistant, relapsed disease remains a significant clinical problem. Recently, the cell surface protein CD133 was identified as a putative marker of tumor-initiating cells in ESFT. We evaluated ESFT tumors and cell lines to determine if high levels of CD133 are associated with drug resistance. METHODS: Expression of the CD133-encoding PROM1 gene was determined by RT-PCR in ESFT tumors and cell lines. CD133 protein expression was assessed by western blot, FACS and/or immunostaining. Cell lines were FACS-sorted into CD133+ and CD133- fractions and proliferation, colony formation in soft agar, and in vivo tumorigenicity compared. Chemosensitivity was measured using MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxy-methoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assays. RESULTS: PROM1 expression was either absent or extremely low in most tumors. However, PROM1 was highly over-expressed in 4 of 48 cases. Two of the 4 patients with PROM1 over-expressing tumors rapidly succumbed to primary drug-resistant disease and two are long-term, event-free survivors. The expression of PROM1 in ESFT cell lines was similarly heterogeneous. The frequency of CD133+ cells ranged from 2-99% and, with one exception, no differences in the chemoresistance or tumorigenicity of CD133+ and CD133- cell fractions were detected. Importantly, however, the STA-ET-8.2 cell line was found to retain a cellular hierarchy in which relatively chemo-resistant, tumorigenic CD133+ cells gave rise to relatively chemo-sensitive, less tumorigenic, CD133- progeny. CONCLUSIONS: Up to 10% of ESFT express high levels of PROM1. In some tumors and cell lines the CD133+ fraction is relatively more drug-resistant, while in others there is no apparent difference between CD133+ and CD133- cells. These studies reveal heterogeneity in PROM1/CD133 expression in ESFT tumors and cell lines and confirm that high levels of PROM1 expression are, in at least some cases, associated with chemo-resistant disease. Further studies are required to elucidate the contribution of PROM1/CD133 expressing cells to therapeutic resistance in a large, prospective cohort of primary ESFT.
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Antígenos CD/biosíntesis , Regulación Neoplásica de la Expresión Génica , Glicoproteínas/biosíntesis , Sarcoma de Ewing/metabolismo , Antígeno AC133 , Animales , Antígenos CD/metabolismo , Separación Celular , Estudios de Cohortes , Resistencia a Antineoplásicos , Citometría de Flujo/métodos , Glicoproteínas/metabolismo , Humanos , Ratones , Ratones Endogámicos NOD , Ratones SCID , Péptidos/metabolismo , Recurrencia , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
YAP and TAZ are intracellular messengers communicating multiple interacting extracellular biophysical and biochemical cues to the transcription apparatus in the nucleus and back to the cell/tissue microenvironment interface through the regulation of cytoskeletal and extracellular matrix components. Their activity is negatively and positively controlled by multiple phosphorylation events. Phenotypically, they serve an important role in cellular plasticity and lineage determination during development. As they regulate self-renewal, proliferation, migration, invasion and differentiation of stem cells, perturbed expression of YAP/TAZ signaling components play important roles in tumorigenesis and metastasis. Despite their high structural similarity, YAP and TAZ are functionally not identical and may play distinct cell type and differentiation stage-specific roles mediated by a diversity of downstream effectors and upstream regulatory molecules. However, YAP and TAZ are frequently looked at as functionally redundant and are not sufficiently discriminated in the scientific literature. As the extracellular matrix composition and mechanosignaling are of particular relevance in bone formation during embryogenesis, post-natal bone elongation and bone regeneration, YAP/TAZ are believed to have critical functions in these processes. Depending on the differentiation stage of mesenchymal stem cells during endochondral bone development, YAP and TAZ serve distinct roles, which are also reflected in bone tumors arising from the mesenchymal lineage at different developmental stages. Efforts to clinically translate the wealth of available knowledge of the pathway for cancer diagnostic and therapeutic purposes focus mainly on YAP and TAZ expression and their role as transcriptional co-activators of TEAD transcription factors but rarely consider the expression and activity of pathway modulatory components and other transcriptional partners of YAP and TAZ. As there is a growing body of evidence for YAP and TAZ as potential therapeutic targets in several cancers, we here interrogate the applicability of this concept to bone tumors. To this end, this review aims to summarize our current knowledge of YAP and TAZ in cell plasticity, normal bone development and bone cancer.
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Proteínas Adaptadoras Transductoras de Señales/metabolismo , Neoplasias Óseas/metabolismo , Neoplasias Óseas/patología , Carcinogénesis/metabolismo , Osteogénesis , Sarcoma/metabolismo , Transducción de Señal , Transactivadores/metabolismo , Animales , Neoplasias Óseas/genética , Carcinogénesis/genética , Carcinogénesis/patología , Humanos , Sarcoma/genética , Sarcoma/patologíaRESUMEN
BACKGROUND: Ewing sarcoma (EwS) is a rare, aggressive solid tumor of childhood, adolescence and young adulthood associated with pathognomonic EWSR1-ETS fusion oncoproteins altering transcriptional regulation. Genome-wide association studies (GWAS) have identified 6 common germline susceptibility loci but have not investigated low-frequency inherited variants with minor allele frequencies below 5% due to limited genotyped cases of this rare tumor. METHODS: We investigated the contribution of rare and low-frequency variation to EwS susceptibility in the largest EwS genome-wide association study to date (733 EwS cases and 1,346 unaffected controls of European ancestry). RESULTS: We identified two low-frequency variants, rs112837127 and rs2296730, on chromosome 20 that were associated with EwS risk (OR = 0.186 and 2.038, respectively; P-value < 5×10-8) and located near previously reported common susceptibility loci. After adjusting for the most associated common variant at the locus, only rs112837127 remained a statistically significant independent signal (OR = 0.200, P-value = 5.84×10-8). CONCLUSIONS: These findings suggest rare variation residing on common haplotypes are important contributors to EwS risk. IMPACT: Motivate future targeted sequencing studies for a comprehensive evaluation of low-frequency and rare variation around common EwS susceptibility loci.
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Sitios Genéticos , Predisposición Genética a la Enfermedad , Variación Genética , Células Germinativas/metabolismo , Sarcoma de Ewing/genética , Estudio de Asociación del Genoma Completo , Humanos , Desequilibrio de Ligamiento/genética , Oportunidad Relativa , Polimorfismo de Nucleótido Simple/genéticaRESUMEN
The glucocorticoid receptor (GR) acts as a ubiquitous cortisol-dependent transcription factor (TF). To identify co-factors, we used protein-fragment complementation assays and found that GR recognizes FLI1 and additional ETS family proteins, TFs relaying proliferation and/or migration signals. Following steroid-dependent translocation of FLI1 and GR to the nucleus, the FLI1-specific domain (FLS) binds with GR and strongly enhances GR's transcriptional activity. This interaction has functional consequences in Ewing sarcoma (ES), childhood and adolescence bone malignancies driven by fusions between EWSR1 and FLI1. In vitro, GR knockdown inhibited the migration and proliferation of ES cells, and in animal models, antagonizing GR (or lowering cortisol) retarded both tumor growth and metastasis from bone to lung. Taken together, our findings offer mechanistic rationale for repurposing GR-targeting drugs for the treatment of patients with ES.
Asunto(s)
Proteínas Proto-Oncogénicas c-ets/metabolismo , Receptores de Glucocorticoides/metabolismo , Sarcoma de Ewing/metabolismo , Animales , Neoplasias Óseas/metabolismo , Movimiento Celular/fisiología , Núcleo Celular/metabolismo , Proliferación Celular/fisiología , Femenino , Regulación Neoplásica de la Expresión Génica/fisiología , Células HEK293 , Humanos , Ratones , Ratones SCID , Proteína Proto-Oncogénica c-fli-1/metabolismo , Proteína EWS de Unión a ARN/metabolismoRESUMEN
An amendment to this paper has been published and can be accessed via a link at the top of the paper.