RESUMEN
Epithelial-mesenchymal transition (EMT) encompasses dynamic changes in cellular organization from epithelial to mesenchymal phenotypes, which leads to functional changes in cell migration and invasion. EMT occurs in a diverse range of physiological and pathological conditions and is driven by a conserved set of inducing signals, transcriptional regulators and downstream effectors. With over 5,700 publications indexed by Web of Science in 2019 alone, research on EMT is expanding rapidly. This growing interest warrants the need for a consensus among researchers when referring to and undertaking research on EMT. This Consensus Statement, mediated by 'the EMT International Association' (TEMTIA), is the outcome of a 2-year-long discussion among EMT researchers and aims to both clarify the nomenclature and provide definitions and guidelines for EMT research in future publications. We trust that these guidelines will help to reduce misunderstanding and misinterpretation of research data generated in various experimental models and to promote cross-disciplinary collaboration to identify and address key open questions in this research field. While recognizing the importance of maintaining diversity in experimental approaches and conceptual frameworks, we emphasize that lasting contributions of EMT research to increasing our understanding of developmental processes and combatting cancer and other diseases depend on the adoption of a unified terminology to describe EMT.
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Investigación Biomédica/normas , Transición Epitelial-Mesenquimal , Animales , Movimiento Celular , Plasticidad de la Célula , Consenso , Biología Evolutiva/normas , Humanos , Neoplasias/patología , Terminología como AsuntoRESUMEN
B-cell acute lymphoblastic leukemia (B-ALL) is the most common pediatric cancer, with long-term overall survival rates of ~85%. However, B-ALL harboring rearrangements of the MLL gene (also known as KMT2A), referred to as MLLr B-ALL, is common in infants and is associated with poor 5-year survival (<30%), frequent relapses, and refractoriness to glucocorticoids (GCs). GCs are an essential part of the treatment backbone for B-ALL and GC resistance is a major clinical predictor of poor outcome. Elucidating the mechanisms of GC resistance in MLLr B-ALL is, therefore, critical to guide therapeutic strategies that deepen the response after induction therapy. Neuron-glial antigen-2 (NG2) expression is a hallmark of MLLr B-ALL and is minimally expressed in healthy hematopoietic cells. We recently reported that NG2 expression is associated with poor prognosis and that anti-NG2 immunotherapy strongly reduces/delays relapse in MLLr B-ALL xenograft models. Despite its contribution to MLLr B-ALL pathogenesis and its diagnostic utility, the role of NG2 in MLLr-mediated leukemogenesis/chemoresistance remains elusive. Here we show that NG2 is an epigenetically regulated direct target gene of the leukemic MLL-AF4 fusion protein. NG2 negatively regulates the expression of the GC receptor NR3C1 and confers GC resistance to MLLr B-ALL cells in vitro and in vivo. Mechanistically, NG2 interacts with FLT3 to render ligand-independent activation of FLT3 signaling (a hallmark of MLLr B-ALL) and downregulation of NR3C1 via AP-1-mediated trans-repression. Collectively, our study elucidates the role of NG2 in GC resistance in MLLr B-ALL through FLT3/AP-1-mediated downregulation of NR3C1, providing novel therapeutic avenues for MLLr B-ALL.
RESUMEN
Colon tumors of the mesenchymal subtype have the lowest overall survival. Snail1 is essential for the acquisition of this phenotype, characterized by increased tumor stemness and invasion, and high resistance to chemotherapy. Here, we find that Snail1 expression in colon tumor cells is dependent on an autocrine noncanonical Wnt pathway. Accordingly, depletion of Ror2, the co-receptor for noncanonical Wnts such as Wnt5a, potently decreases Snail1 expression. Wnt5a, Ror2, and Snail1 participate in a self-stimulatory feedback loop since Wnt5a increases its own synthesis in a Ror2- and Snail1-dependent fashion. This Wnt5a/Ror2/Snail1 axis controls tumor invasion, chemoresistance, and formation of tumor spheres. It also stimulates TGFß synthesis; consequently, tumor cells expressing Snail1 are more efficient in activating cancer-associated fibroblasts than the corresponding controls. Ror2 downmodulation or inhibition of the Wnt5a pathway decreases Snail1 expression in primary colon tumor cells and their ability to form tumors and liver metastases. Finally, the expression of SNAI1, ROR2, and WNT5A correlates in human colon and other tumors. These results identify inhibition of the noncanonical Wnt pathway as a putative colon tumor therapy.
Asunto(s)
Neoplasias del Colon , Vía de Señalización Wnt , Humanos , Resistencia a Antineoplásicos/genética , Neoplasias del Colon/tratamiento farmacológico , Neoplasias del Colon/genética , FibroblastosRESUMEN
BACKGROUND: As in most solid cancers, the emergence of cells with oncogenic mutations in the mammary epithelium alters the tissue homeostasis. Some soluble factors, such as TGFß, potently modify the behavior of healthy stromal cells. A subpopulation of cancer-associated fibroblasts expressing a TGFß target, the SNAIL1 transcription factor, display myofibroblastic abilities that rearrange the stromal architecture. Breast tumors with the presence of SNAIL1 in the stromal compartment, and with aligned extracellular fiber, are associated with poor survival prognoses. METHODS: We used deep RNA sequencing and biochemical techniques to study alternative splicing and human tumor databases to test for associations (correlation t-test) between SNAIL1 and fibronectin isoforms. Three-dimensional extracellular matrices generated from fibroblasts were used to study the mechanical properties and actions of the extracellular matrices on tumor cell and fibroblast behaviors. A metastatic mouse model of breast cancer was used to test the action of fibronectin isoforms on lung metastasis. RESULTS: In silico studies showed that SNAIL1 correlates with the expression of the extra domain A (EDA)-containing (EDA+) fibronectin in advanced human breast cancer and other types of epithelial cancers. In TGFß-activated fibroblasts, alternative splicing of fibronectin as well as of 500 other genes was modified by eliminating SNAIL1. Biochemical analyses demonstrated that SNAIL1 favors the inclusion of the EDA exon by modulating the activity of the SRSF1 splicing factor. Similar to Snai1 knockout fibroblasts, EDA- fibronectin fibroblasts produce an extracellular matrix that does not sustain TGFß-induced fiber organization, rigidity, fibroblast activation, or tumor cell invasion. The presence of EDA+ fibronectin changes the action of metalloproteinases on fibronectin fibers. Critically, in an mouse orthotopic breast cancer model, the absence of the fibronectin EDA domain completely prevents lung metastasis. CONCLUSIONS: Our results support the requirement of EDA+ fibronectin in the generation of a metastasis permissive stromal architecture in breast cancers and its molecular control by SNAIL1. From a pharmacological point of view, specifically blocking EDA+ fibronectin deposition could be included in studies to reduce the formation of a pro-metastatic environment.
Asunto(s)
Neoplasias de la Mama , Neoplasias Pulmonares , Animales , Femenino , Humanos , Ratones , Empalme Alternativo , Neoplasias de la Mama/genética , Fibronectinas/genética , Fibronectinas/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Factores de Empalme Serina-Arginina/genética , Factores de Empalme Serina-Arginina/metabolismo , Factor de Crecimiento Transformador beta/metabolismoRESUMEN
Protein function is often regulated and controlled by posttranslational modifications, such as oxidation. Although oxidation has been mainly considered to be uncontrolled and nonenzymatic, many enzymatic oxidations occur on enzyme-selected lysine residues; for instance, LOXL2 oxidizes lysines by converting the ε-amino groups into aldehyde groups. Using an unbiased proteomic approach, we have identified methylated TAF10, a member of the TFIID complex, as a LOXL2 substrate. LOXL2 oxidation of TAF10 induces its release from its promoters, leading to a block in TFIID-dependent gene transcription. In embryonic stem cells, this results in the inactivation of the pluripotency genes and loss of the pluripotent capacity. During zebrafish development, the absence of LOXL2 resulted in the aberrant overexpression of the neural progenitor gene Sox2 and impaired neural differentiation. Thus, lysine oxidation of the transcription factor TAF10 is a controlled protein modification and demonstrates a role for protein oxidation in regulating pluripotency genes.
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Aminoácido Oxidorreductasas/fisiología , Diferenciación Celular , Células-Madre Neurales/fisiología , Procesamiento Proteico-Postraduccional , Factores Asociados con la Proteína de Unión a TATA/metabolismo , Factor de Transcripción TFIID/fisiología , Animales , Epigénesis Genética , Células HEK293 , Humanos , Metilación , Oxidación-Reducción , Factor de Transcripción TFIID/metabolismo , Pez CebraRESUMEN
The Wnt canonical ligands elicit the activation of ß-catenin transcriptional activity, a response dependent on, but not limited to, ß-catenin stabilization through the inhibition of GSK3 activity. Two mechanisms have been proposed for this inhibition, one dependent on the binding and subsequent block of GSK3 to LRP5/6 Wnt coreceptor and another one on its sequestration into multivesicular bodies (MVBs). Here we report that internalization of the GSK3-containing Wnt-signalosome complex into MVBs is dependent on the dissociation of p120-catenin/cadherin from this complex. Disruption of cadherin-LRP5/6 interaction is controlled by cadherin phosphorylation and requires the previous separation of p120-catenin; thus, p120-catenin and cadherin mutants unable to dissociate from the complex block GSK3 sequestration into MVBs. These mutants substantially inhibit, but do not completely prevent, the ß-catenin upregulation caused by Wnt3a. These results, besides elucidating how GSK3 is sequestered into MVBs, support this mechanism as cause of ß-catenin stabilization by Wnt.
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Cadherinas/fisiología , Cateninas/fisiología , Glucógeno Sintasa Quinasa 3/metabolismo , Proteína-5 Relacionada con Receptor de Lipoproteína de Baja Densidad/metabolismo , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Cuerpos Multivesiculares/metabolismo , Vía de Señalización Wnt , Animales , Cadherinas/metabolismo , Cateninas/metabolismo , Caveolinas/metabolismo , Células HEK293 , Humanos , Proteína-5 Relacionada con Receptor de Lipoproteína de Baja Densidad/análisis , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/análisis , Ratones , Fosforilación , Proteína Wnt3A/metabolismo , Proteína Wnt3A/fisiología , Catenina deltaRESUMEN
Although heterochromatin is enriched with repressive traits, it is also actively transcribed, giving rise to large amounts of noncoding RNAs. Although these RNAs are responsible for the formation and maintenance of heterochromatin, little is known about how their transcription is regulated. Here, we show that the Snail1 transcription factor represses mouse pericentromeric transcription, acting through the H3K4 deaminase LOXL2. Since Snail1 plays a key role in the epithelial-to-mesenchymal transition (EMT), we analyzed the regulation of heterochromatin transcription in this process. At the onset of EMT, one of the major structural heterochromatin proteins, HP1α, is transiently released from heterochromatin foci in a Snail1/LOXL2-dependent manner, concomitantly with a downregulation of major satellite transcription. Moreover, preventing the downregulation of major satellite transcripts compromised the migratory and invasive behavior of mesenchymal cells. We propose that Snail1 regulates heterochromatin transcription through LOXL2, thus creating the favorable transcriptional state necessary for completing EMT.
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Aminoácido Oxidorreductasas/genética , Transición Epitelial-Mesenquimal/genética , Heterocromatina/genética , Factores de Transcripción/genética , Transcripción Genética , Animales , Línea Celular , Homólogo de la Proteína Chromobox 5 , Proteínas Cromosómicas no Histona/genética , Regulación hacia Abajo , Células HEK293 , Histonas/genética , Humanos , Mesodermo/metabolismo , Ratones , Factores de Transcripción de la Familia SnailRESUMEN
Wnt ligands signal through canonical or non-canonical signaling pathways. Although both routes share common elements, such as the Fz2 receptor, they differ in the co-receptor and in many of the final responses; for instance, whereas canonical Wnts increase ß-catenin stability, non-canonical ligands downregulate it. However, both types of ligands stimulate tumor cell invasion. We show here that both the canonical Wnt3a and the non-canonical Wnt5a stimulate Fz2 tyrosine phosphorylation, Fyn binding to Fz2, Fyn activation and Fyn-dependent Stat3 phosphorylation. Wnt3a and Wnt5a require Src for Fz2 tyrosine phosphorylation; Src binds to canonical and non-canonical co-receptors (LRP5/6 and Ror2, respectively) and is activated by Wnt3a and Wnt5a. This Fz2/Fyn/Stat3 branch is incompatible with the classical Fz2/Dvl2 pathway as shown by experiments of over-expression or depletion. Fyn is necessary for transcription of genes associated with invasiveness, such as Snail1, and for activation of cell invasion by both Wnt ligands. Our results extend the knowledge about canonical Wnt pathways, demonstrating additional roles for Fyn in this pathway and describing how this protein kinase is activated by both canonical and non-canonical Wnts.
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Receptores Frizzled/metabolismo , Proteínas Proto-Oncogénicas c-fyn/metabolismo , Proteína Wnt-5a/metabolismo , Proteína Wnt3A/metabolismo , Familia-src Quinasas/metabolismo , Línea Celular , Activación Enzimática/genética , Células HEK293 , Humanos , Proteína-5 Relacionada con Receptor de Lipoproteína de Baja Densidad/metabolismo , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Invasividad Neoplásica/genética , Neoplasias/patología , Fosforilación/fisiología , Receptores Huérfanos Similares al Receptor Tirosina Quinasa/metabolismo , Factor de Transcripción STAT3/metabolismo , Transcripción Genética/genética , Vía de Señalización Wnt/fisiología , beta Catenina/metabolismoRESUMEN
Methylation of lysine 4 (K4) within histone H3 has been linked to active transcription and is removed by LSD1 and the JmjC domain-containing proteins by amino-oxidation or hydroxylation, respectively. Here, we describe the deamination catalyzed by Lysyl oxidase-like 2 protein (LOXL2) as an unconventional chemical mechanism for H3K4 modification. Infrared spectroscopy and mass spectrometry analyses demonstrated that recombinant LOXL2 specifically deaminates trimethylated H3K4. Moreover, LOXL2 activity is linked with the transcriptional control of CDH1 gene by regulating H3K4me3 deamination. These results reveal another H3 modification and provide a different mechanism for H3K4 modification.
Asunto(s)
Aminoácido Oxidorreductasas/fisiología , Histonas/metabolismo , Antígenos CD , Cadherinas/genética , Línea Celular Tumoral , Desaminación , Regulación de la Expresión Génica , Humanos , Lisina/metabolismo , MetilaciónRESUMEN
Besides controlling epithelial-to-mesenchymal transition (EMT) and cell invasion, the Snail1 transcriptional factor also provides cells with cancer stem cell features. Since telomere maintenance is essential for stemness, we have examined the control of telomere integrity by Snail1. Fluorescence in situ hybridization (FISH) analysis indicates that Snail1-depleted mouse mesenchymal stem cells (MSC) have both a dramatic increase of telomere alterations and shorter telomeres. Remarkably, Snail1-deficient MSC present higher levels of both telomerase activity and the long non-coding RNA called telomeric repeat-containing RNA (TERRA), an RNA that controls telomere integrity. Accordingly, Snail1 expression downregulates expression of the telomerase gene (TERT) as well as of TERRA 2q, 11q and 18q. TERRA and TERT are transiently downregulated during TGFß-induced EMT in NMuMG cells, correlating with Snail1 expression. Global transcriptome analysis indicates that ectopic expression of TERRA affects the transcription of some genes induced during EMT, such as fibronectin, whereas that of TERT does not modify those genes. We propose that Snail1 repression of TERRA is required not only for telomere maintenance but also for the expression of a subset of mesenchymal genes.
Asunto(s)
Regulación de la Expresión Génica , Factores de Transcripción de la Familia Snail/genética , Homeostasis del Telómero/genética , Telómero/genética , Animales , Línea Celular , Células Cultivadas , Transición Epitelial-Mesenquimal/genética , Perfilación de la Expresión Génica/métodos , Humanos , Células Madre Mesenquimatosas/metabolismo , Ratones Noqueados , Células Madre Neoplásicas/metabolismo , ARN Largo no Codificante/genética , Factores de Transcripción de la Familia Snail/metabolismo , Telomerasa/genética , Telomerasa/metabolismo , Telómero/enzimologíaRESUMEN
Canonical Wnt signaling controls ß-catenin protein stabilization, its translocation to the nucleus and the activation of ß-catenin/Tcf-4-dependent transcription. In this review, we revise and discuss the recent results describing actions of p120-catenin in different phases of this pathway. More specifically, we comment its involvement in four different steps: (i) the very early activation of CK1É, essential for Dvl-2 binding to the Wnt receptor complex; (ii) the internalization of GSK3 and Axin into multivesicular bodies, necessary for a complete stabilization of ß-catenin; (iii) the activation of Rac1 small GTPase, required for ß-catenin translocation to the nucleus; and (iv) the release of the inhibitory action caused by Kaiso transcriptional repressor. We integrate these new results with the previously known action of other elements in this pathway, giving a particular relevance to the responses of the Wnt pathway not required for ß-catenin stabilization but for ß-catenin transcriptional activity. Moreover, we discuss the possible future implications, suggesting that the two cellular compartments where ß-catenin is localized, thus, the adherens junction complex and the Wnt signalosome, are more physically connected that previously thought.
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Cateninas/metabolismo , Receptores Wnt/metabolismo , Transcripción Genética/fisiología , Vía de Señalización Wnt/fisiología , Animales , Proteínas Dishevelled/metabolismo , Proteínas de Drosophila/metabolismo , Humanos , Factores de Transcripción/metabolismo , beta Catenina/metabolismo , Proteínas de Unión al GTP rac/metabolismo , Catenina deltaRESUMEN
Myofibroblasts are a population of highly contractile fibroblasts that express and require the activity of the transcription factor Snail1. Cancer-associated fibroblasts (CAFs) correlate with low survival of cancer patients when present in the stroma of primary tumors. Remarkably, the presence of myofibroblastic CAFs (which express Snail1) creates mechanical properties in the tumor microenvironment that support metastasis. However, therapeutic blockage of fibroblast activity in patients with cancer is a double-edged sword, as normal fibroblast activities often restrict tumor cell invasion. We used fibroblasts depleted of Snail1 or protein arginine methyltransferases 1 and 4 (PRMT1/-4) to identify specific epigenetic modifications induced by TGFß/Snail1. Furthermore, we analyzed the in vivo efficiency of methyltransferase inhibitors using mouse models of wound healing and metastasis, as well as fibroblasts isolated from patients with idiopathic pulmonary fibrosis (IPF). Mechanistically, TGFß-induced Snail1 promotes the epigenetic mark of asymmetrically dimethylated arginine. Critically, we found that inhibitors of methyltransferases prevent myofibroblast activity (but not regular fibroblast activity) in the extracellular matrix, both in cell culture and in vivo. In a mouse breast cancer model, the inhibitor sinefungin reduces both the myofibroblast activity in the tumor stroma and the metastatic burden in the lung. Two distinct inhibitors effectively blocked the exacerbated myofibroblast activity of patient-derived IPF fibroblasts. Our data reveal epigenetic regulation of myofibroblast transdifferentiation in both wound healing and in disease (fibrosis and breast cancer). Thus, methyltransferase inhibitors are good candidates as therapeutic reagents for these diseases.
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Neoplasias de la Mama/tratamiento farmacológico , Inhibidores Enzimáticos/administración & dosificación , Fibrosis Pulmonar Idiopática/tratamiento farmacológico , Neoplasias Pulmonares/secundario , Metiltransferasas/antagonistas & inhibidores , Miofibroblastos/efectos de los fármacos , Factores de Transcripción de la Familia Snail/genética , Adenosina/administración & dosificación , Adenosina/análogos & derivados , Adenosina/farmacología , Animales , Neoplasias de la Mama/enzimología , Fibroblastos Asociados al Cáncer/citología , Fibroblastos Asociados al Cáncer/efectos de los fármacos , Fibroblastos Asociados al Cáncer/metabolismo , Línea Celular Tumoral , Transdiferenciación Celular , Células Cultivadas , Modelos Animales de Enfermedad , Inhibidores Enzimáticos/farmacología , Epigénesis Genética , Femenino , Eliminación de Gen , Humanos , Fibrosis Pulmonar Idiopática/enzimología , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/enzimología , Metiltransferasas/genética , Ratones , Miofibroblastos/citología , Miofibroblastos/enzimología , Factores de Transcripción de la Familia Snail/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Microambiente Tumoral , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Adipogenesis requires a differentiation program driven by multiple transcription factors, where PPARγ and C/EBPα play a central role. Recent findings indicate that Snail inhibits adipocyte differentiation in 3T3-L1 and murine mesenchymal stem cells (mMSC). An in-depth quantitative SILAC analysis of the nuclear fraction of Snail-induced alterations of 3T3-L1 cells was carried out. In total, 2251 overlapping proteins were simultaneously quantified in forward and reverse experiments. We observed 574 proteins deregulated by Snail1 using a fold-change ≥1.5, with 111 up- and 463 down-regulated proteins, respectively. Among other proteins, multiple transcription factors such as Trip4, OsmR, Nr2f6, Cbx6, and Prrx1 were down-regulated. Results were validated in 3T3-L1 cells and mMSC cells by Western blot and quantitative PCR. Knock-down experiments in 3T3-L1 cells demonstrated that only Nr2f6 (and Trip4 at minor extent) was required for adipocyte differentiation. Ectopic expression of Nr2f6 reversed the effects of Snail1 and promoted adipogenesis. Because Nr2f6 inhibits the expression of IL-17, we tested the effect of Snail on IL-17 expression. IL-17 and TNFα were among the most up-regulated pro-inflammatory cytokines in Snail-transfected 3T3-L1 and mMSC cells. Furthermore, the blocking of IL-17 activity in Snail-transfected cells promoted adipocyte differentiation, reverting Snail inhibition. In summary, Snail inhibits adipogenesis through a down-regulation of Nr2f6, which in turn facilitates the expression of IL-17, an anti-adipogenic cytokine. These results would support a novel and important role for Snail and Nr2f6 in obesity control.
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Adipocitos/citología , Adipocitos/metabolismo , Factores de Transcripción COUP/metabolismo , Diferenciación Celular , Interleucina-17/metabolismo , Proteómica/métodos , Factores de Transcripción/metabolismo , Células 3T3-L1 , Adipogénesis , Animales , Extractos Celulares , Núcleo Celular/metabolismo , Regulación hacia Abajo , Células Madre Mesenquimatosas/metabolismo , Ratones , Modelos Biológicos , Proteínas Represoras , Reproducibilidad de los Resultados , Transducción de Señal , Factores de Transcripción de la Familia Snail , TransfecciónRESUMEN
The transcription factor Snail1 induces epithelial-to-mesenchymal transition (EMT) in tumor epithelial cells, a process associated with the emergence of stemness, invasion and cancer malignancy. Here, we review recent reports indicating that Snail1 also regulates mesenchymal plasticity and paracrine signaling and propose that Snail1 orchestrates the generation of cancer stem cells (CSCs) and cancer-associated fibroblasts (CAFs). Our view supports the current models for tumorigenesis that consider stemness and tumor microenvironment as retroactive actors for metastasis formation, revealing Snail1 as a regulator of these metastatic forces. This view offers new perspectives for understanding and targeting metastasis.
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Neoplasias/patología , Células Epiteliales/patología , Transición Epitelial-Mesenquimal , Humanos , Células Madre Mesenquimatosas/patología , Neoplasias/fisiopatología , Células Madre Neoplásicas/patología , Factores de Transcripción de la Familia Snail , Factores de TranscripciónRESUMEN
The zinc finger transcription factor Snail1 regulates epithelial to mesenchymal transition, repressing epithelial markers and activating mesenchymal genes. Snail1 is an extremely labile protein degraded by the cytoplasmic ubiquitin-ligases ß-TrCP1/FBXW1 and Ppa/FBXL14. Using a short hairpin RNA screening, we have identified FBXL5 as a novel Snail1 ubiquitin ligase. FBXL5 is located in the nucleus where it interacts with Snail1 promoting its polyubiquitination and affecting Snail1 protein stability and function by impairing DNA binding. Snail1 downregulation by FBXL5 is prevented by Lats2, a protein kinase that phosphorylates Snail1 precluding its nuclear export but not its polyubiquitination. Actually, although polyubiquitination by FBXL5 takes place in the nucleus, Snail1 is degraded in the cytosol. Finally, FBXL5 is highly sensitive to stress conditions and is downregulated by iron depletion and γ-irradiation, explaining Snail1 stabilization in these conditions. These results characterize a novel nuclear ubiquitin ligase controlling Snail1 protein stability and provide the molecular basis for understanding how radiotherapy upregulates the epithelial to mesenchymal transition-inducer Snail1.
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Núcleo Celular/enzimología , Proteínas F-Box/metabolismo , Factores de Transcripción/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , Ubiquitinación , Línea Celular Tumoral , Núcleo Celular/metabolismo , ADN/metabolismo , Rayos gamma , Humanos , Unión Proteica , Proteínas Serina-Treonina Quinasas/metabolismo , Estabilidad Proteica , ARN Interferente Pequeño , Factores de Transcripción de la Familia Snail , Complejos de Ubiquitina-Proteína LigasaRESUMEN
PURPOSE: Epithelial-to-mesenchymal transition is a phenomenon in epithelial tumors that involves loss of intercellular adhesion, mesenchymal phenotype acquisition and enhanced migratory potential. While the epithelial-to-mesenchymal transition process has been extensively linked to metastatic progression of squamous cell carcinoma, studies of the role of epithelial-to-mesenchymal transition in squamous cell carcinoma containing high risk human papillomaviruses are scarce. Moreover, to our knowledge epithelial-to-mesenchymal transition involvement in human penile squamous cell carcinoma, which can arise through transforming HPV infections or independently of HPV, has not been investigated. We evaluated the presence of epithelial-to-mesenchymal transition markers and their relationship to HPV in penile squamous cell carcinoma. MATERIALS AND METHODS: We assessed the expression of E-cadherin, vimentin and the epithelial-to-mesenchymal transition related transcription factors Twist, Zeb1 and Snail by immunohistochemical staining in 64 penile squamous cell carcinoma cases. HPV was detected by polymerase chain reaction amplification. RESULTS: Simultaneous loss of membranous E-cadherin expression and vimentin over expression were noted in 43.5% of penile squamous cell carcinoma cases. HPV was significantly associated with loss of membranous E-cadherin but not with epithelial-to-mesenchymal transition. Recurrence and mortality rates were significantly higher in cases showing epithelial-to-mesenchymal transition. CONCLUSIONS: Our findings indicate that in penile squamous cell carcinoma epithelial-to-mesenchymal transition is associated with poor prognosis but not with the presence of HPV.
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Carcinoma de Células Escamosas/patología , Transición Epitelial-Mesenquimal , Neoplasias del Pene/patología , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma de Células Escamosas/virología , Humanos , Masculino , Persona de Mediana Edad , Infecciones por Papillomavirus/complicaciones , Neoplasias del Pene/virologíaRESUMEN
A role for Rac1 GTPase in canonical Wnt signaling has recently been demonstrated, showing that it is required for ß-catenin translocation to the nucleus. In this study, we investigated the mechanism of Rac1 stimulation by Wnt. Upregulation of Rac1 activity by Wnt3a temporally correlated with enhanced p120-catenin binding to Rac1 and Vav2. Vav2 and Rac1 association with p120-catenin was modulated by phosphorylation of this protein, which was stimulated upon serine/threonine phosphorylation by CK1 and inhibited by tyrosine phosphorylation by Src or Fyn. Acting on these two post-translational modifications, Wnt3a induced the release of p120-catenin from E-cadherin, enabled the interaction of p120-catenin with Vav2 and Rac1, and facilitated Rac1 activation by Vav2. Given that p120-catenin depletion disrupts gastrulation in Xenopus, we analyzed p120-catenin mutants for their ability to rescue this phenotype. In contrast to the wild-type protein or other controls, p120-catenin point mutants that were deficient in the release from E-cadherin or in Vav2 or Rac1 binding failed to rescue p120-catenin depletion. Collectively, these results indicate that binding of p120-catenin to Vav2 and Rac1 is required for the activation of this GTPase upon Wnt signaling.
Asunto(s)
Cateninas/metabolismo , Proteínas Proto-Oncogénicas c-vav/metabolismo , Proteína Wnt3A/farmacología , Proteína de Unión al GTP rac1/metabolismo , Animales , Cadherinas/metabolismo , Línea Celular , Núcleo Celular/efectos de los fármacos , Núcleo Celular/metabolismo , Citosol/efectos de los fármacos , Citosol/metabolismo , Embrión no Mamífero/efectos de los fármacos , Embrión no Mamífero/metabolismo , Activación Enzimática/efectos de los fármacos , Gastrulación/efectos de los fármacos , Humanos , Modelos Biológicos , Proteínas Mutantes/metabolismo , Fosforilación/efectos de los fármacos , Fosfoserina/metabolismo , Fosfotirosina/metabolismo , Unión Proteica/efectos de los fármacos , Transporte de Proteínas/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Xenopus/embriología , Xenopus/metabolismo , beta Catenina/metabolismo , Catenina deltaRESUMEN
Snail1 transcriptional factor plays a key role in the control of epithelial to mesenchymal transition, a process that remodels tumor cells increasing their invasion and chemo-resistance as well as reprograms their metabolism and provides stemness properties. During this transition, Snail1 acts as a transcriptional repressor and, as growing evidences have demonstrated, also as a direct activator of mesenchymal genes. In this review, I describe the different proteins that interact with Snail1 and are responsible for these two different functions on gene expression; I focus on the transcriptional factors that associate to Snail1 in their target promoters, both activated and repressed. I also present working models for Snail1 action both as repressor and activator and raise some issues that still need to be investigated.