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The quest for targeted therapies is critical in the battle against cancer. The RAS/MAP kinase pathway is frequently implicated in neoplasia, with ERK playing a crucial role as the most distal kinase in the RAS signaling cascade. Our previous research demonstrated that the interaction between ERK and MYD88, an adaptor protein in innate immunity, is crucial for RAS-dependent transformation and cancer cell survival. In this study, we examine the biological consequences of disrupting the ERK-MYD88 interaction through the ERK D-recruitment site (DRS), while preserving ERK's kinase activity. Our results indicate that EI-52, a small-molecule benzimidazole targeting ERK-MYD88 interaction induces an HRI-mediated integrated stress response (ISR), resulting in immunogenic apoptosis specific to cancer cells. Additionally, EI-52 exhibits anti-tumor efficacy in patient-derived tumors and induces an anti-tumor T cell response in mice in vivo. These findings suggest that inhibiting the ERK-MYD88 interaction may be a promising therapeutic approach in cancer treatment.
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Bencimidazoles , Quinasas MAP Reguladas por Señal Extracelular , Factor 88 de Diferenciación Mieloide , Factor 88 de Diferenciación Mieloide/metabolismo , Factor 88 de Diferenciación Mieloide/genética , Humanos , Animales , Ratones , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Línea Celular Tumoral , Bencimidazoles/farmacología , Apoptosis/efectos de los fármacos , Muerte Celular Inmunogénica/efectos de los fármacos , Neoplasias/inmunología , Neoplasias/tratamiento farmacológico , Neoplasias/patología , Neoplasias/metabolismo , Femenino , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Sistema de Señalización de MAP Quinasas/inmunología , Ensayos Antitumor por Modelo de Xenoinjerto , Antineoplásicos/farmacología , Antineoplásicos/uso terapéuticoRESUMEN
Nutrient availability is a key determinant of tumor cell behavior. While nutrient-rich conditions favor proliferation and tumor growth, scarcity, and particularly glutamine starvation, promotes cell dedifferentiation and chemoresistance. Here, linking ribosome biogenesis plasticity with tumor cell fate, we uncover that the amino acid sensor general control non-derepressible 2 (GCN2; also known as eIF-2-alpha kinase 4) represses the expression of the precursor of ribosomal RNA (rRNA), 47S, under metabolic stress. We show that blockade of GCN2 triggers cell death by an irremediable nucleolar stress and subsequent TP53-mediated apoptosis in patient-derived models of colon adenocarcinoma (COAD). In nutrient-rich conditions, a cell-autonomous GCN2 activity supports cell proliferation by stimulating 47S rRNA transcription, independently of the canonical integrated stress response (ISR) axis. Impairment of GCN2 activity prevents nuclear translocation of methionyl-tRNA synthetase (MetRS), resulting in nucleolar stress, mTORC1 inhibition and, ultimately, autophagy induction. Inhibition of the GCN2-MetRS axis drastically improves the cytotoxicity of RNA polymerase I (RNA pol I) inhibitors, including the first-line chemotherapy oxaliplatin, on patient-derived COAD tumoroids. Our data thus reveal that GCN2 differentially controls ribosome biogenesis according to the nutritional context. Furthermore, pharmacological co-inhibition of the two GCN2 branches and RNA pol I activity may represent a valuable strategy for elimination of proliferative and metabolically stressed COAD cells.
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Reactive oxygen species (ROS) are considered to be the main drivers of inflammatory bowel disease. We investigated whether this permanent insult compels intestinal stem cells to develop strategies to dampen the deleterious effects of ROS. As an adverse effect, this adaptation process may increase their tolerance to oncogenic insults and facilitate their neoplastic transformation. We submitted immortalized human colonic epithelial cells to either a mimic of chronic inflammation or to a chemical peroxide, analyzed how they adapted to stress, and addressed the biological relevance of these observations in databases. We demonstrated that cells adapt to chronic-inflammation-associated oxidative stress in vitro through a partial genetic reprogramming. Through a gene set enrichment analysis, we showed that this program is recurrently active in the intestinal mucosae of Crohn's and ulcerative colitis disease patients and evolves alongside disease progression. Based on a previously reported characterization of intestinal stem and precursor cells using tracing experiments, we lastly confirmed the activation of the program in intestinal precursor cells during murine colorectal cancer development. This adaptive process is thus likely to play a role in the progression of Crohn's and ulcerative disease, and potentially in the initiation of colorectal cancer.
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The kynurenine pathway has been highlighted as a gatekeeper of immune-privileged sites through its ability to generate from tryptophan a set of immunosuppressive metabolic intermediates. It additionally constitutes an important source of cellular NAD+ for the organism. Hijacking of its immunosuppressive functions, as recurrently observed in multiple cancers, facilitates immune evasion and promotes tumor development. Based on these observations, researchers have focused on characterizing indoleamine 2,3-dioxygenase (IDO1), the main enzyme catalyzing the first and limiting step of the pathway, and on developing therapies targeting it. Unfortunately, clinical trials studying IDO1 inhibitors have thus far not met expectations, highlighting the need to unravel this complex signaling pathway further. Recent advances demonstrate that these metabolites additionally promote tumor growth, metastatic dissemination and chemoresistance by a combination of paracrine and autocrine effects. Production of NAD+ also contributes to cancer progression by providing cancer cells with enhanced plasticity, invasive properties and chemoresistance. A comprehensive survey of this complexity is challenging but necessary to achieve medical success.
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Our previous work demonstrated a key function of the thyroid hormone nuclear receptor TRα1, a T3-modulated transcription factor, in controlling intestinal development and homeostasis via the Wnt and Notch pathways. Importantly, increased expression of TRα1 in the intestinal epithelium in a mutated Apc genetic background (vil-TRα1/Apc+/1638N mice) accelerated tumorigenesis and contributed to a more aggressive tumor phenotype compared to that of the Apc mutants alone. Therefore, the aim of this study was to determine the relevance of this synergistic effect in human colorectal cancers and to gain insights into the mechanisms involved. We analyzed cohorts of patients by in silico and experimental approaches and observed increased TRα1 expression and a significant correlation between TRα1 levels and Wnt activity. TRα1 loss-of-function and gain-of-function in Caco2 cell lines not only confirmed that TRα1 levels control Wnt activity but also demonstrated the role of TRα1 in regulating cell proliferation and migration. Finally, upon investigation of the molecular mechanisms responsible for the Wnt-TRα1 association, we described the repression by TRα1 of several Wnt inhibitors, including Frzb, Sox17 and Wif1. In conclusion, our results underline an important functional interplay between the thyroid hormone nuclear receptor TRα1 and the canonical Wnt pathway in intestinal cancer initiation and progression. More importantly, we show for the first time that the expression of TRα1 is induced in human colorectal cancers.
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BACKGROUND: The bHLH transcription factor TWIST1 plays a key role in the embryonic development and in tumorigenesis. Some loss-of-function mutations of the TWIST1 gene have been shown to cause an autosomal dominant craniosynostosis, known as the Saethre-Chotzen syndrome (SCS). Although the functional impacts of many TWIST1 mutations have been experimentally reported, little is known on the molecular mechanisms underlying their loss-of-function. In a previous study, we highlighted the predictive value of in silico molecular dynamics (MD) simulations in deciphering the molecular function of TWIST1 residues. RESULTS: Here, since the substitution of the arginine 154 amino acid by a glycine residue (R154G) is responsible for the SCS phenotype and the substitution of arginine 154 by a proline experimentally decreases the dimerizing ability of TWIST1, we investigated the molecular impact of this point mutation using MD approaches. Consistently, MD simulations highlighted a clear decrease in the stability of the α-helix during the dimerization of the mutated R154P TWIST1/E12 dimer compared to the wild-type TE complex, which was further confirmed in vitro using immunoassays. CONCLUSIONS: Our study demonstrates that MD simulations provide a structural explanation for the loss-of-function associated with the SCS TWIST1 mutation and provides a proof of concept of the predictive value of these MD simulations. This in silico methodology could be used to determine reliable pharmacophore sites, leading to the application of docking approaches in order to identify specific inhibitors of TWIST1 complexes.
Asunto(s)
Simulación de Dinámica Molecular , Proteínas Nucleares/química , Proteínas Nucleares/genética , Mutación Puntual , Factor de Transcripción 3/química , Proteína 1 Relacionada con Twist/química , Proteína 1 Relacionada con Twist/genética , Secuencia de Aminoácidos , Animales , Arginina/química , Arginina/genética , Simulación por Computador , Cristalografía por Rayos X , Glicina/química , Glicina/genética , Humanos , Ratones , Fosforilación , Conformación Proteica , Multimerización de Proteína , Homología de Secuencia , Factor de Transcripción 3/genéticaRESUMEN
Chromosomal instability (CIN), a feature of most adult neoplasms from their early stages onward, is a driver of tumorigenesis. However, several malignancy subtypes, including some triple-negative breast cancers, display a paucity of genomic aberrations, thus suggesting that tumor development may occur in the absence of CIN. Here we show that the differentiation status of normal human mammary epithelial cells dictates cell behavior after an oncogenic event and predetermines the genetic routes toward malignancy. Whereas oncogene induction in differentiated cells induces massive DNA damage, mammary stem cells are resistant, owing to a preemptive program driven by the transcription factor ZEB1 and the methionine sulfoxide reductase MSRB3. The prevention of oncogene-induced DNA damage precludes induction of the oncosuppressive p53-dependent DNA-damage response, thereby increasing stem cells' intrinsic susceptibility to malignant transformation. In accord with this model, a subclass of breast neoplasms exhibit unique pathological features, including high ZEB1 expression, a low frequency of TP53 mutations and low CIN.
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Neoplasias de la Mama/genética , Carcinoma/genética , Diferenciación Celular/genética , Células Epiteliales/metabolismo , Regulación Neoplásica de la Expresión Génica , Inestabilidad Genómica/genética , Metionina Sulfóxido Reductasas/genética , Células Madre/metabolismo , Homeobox 1 de Unión a la E-Box con Dedos de Zinc/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Animales , Neoplasias de la Mama/metabolismo , Carcinoma/metabolismo , Línea Celular Tumoral , Transformación Celular Neoplásica/genética , Inmunoprecipitación de Cromatina , Daño del ADN , Células Epiteliales/citología , Femenino , Citometría de Flujo , Técnica del Anticuerpo Fluorescente , Perfilación de la Expresión Génica , Humanos , Immunoblotting , Glándulas Mamarias Humanas/citología , Metionina Sulfóxido Reductasas/metabolismo , Ratones Endogámicos NOD , Persona de Mediana Edad , Especies Reactivas de Oxígeno , Reacción en Cadena en Tiempo Real de la Polimerasa , Análisis de Secuencia de ADN , Células Madre/citología , Análisis de Matrices Tisulares , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismo , Adulto Joven , Homeobox 1 de Unión a la E-Box con Dedos de Zinc/metabolismoRESUMEN
Targeted therapies with MAPK inhibitors (MAPKi) are faced with severe problems of resistance in BRAF-mutant melanoma. In parallel to the acquisition of genetic mutations, melanoma cells may also adapt to the drugs through phenotype switching. The ZEB1 transcription factor, a known inducer of EMT and invasiveness, is now considered as a genuine oncogenic factor required for tumor initiation, cancer cell plasticity, and drug resistance in carcinomas. Here, we show that high levels of ZEB1 expression are associated with inherent resistance to MAPKi in BRAFV600-mutated cell lines and tumors. ZEB1 levels are also elevated in melanoma cells with acquired resistance and in biopsies from patients relapsing while under treatment. ZEB1 overexpression is sufficient to drive the emergence of resistance to MAPKi by promoting a reversible transition toward a MITFlow/p75high stem-like and tumorigenic phenotype. ZEB1 inhibition promotes cell differentiation, prevents tumorigenic growth in vivo, sensitizes naive melanoma cells to MAPKi, and induces cell death in resistant cells. Overall, our results demonstrate that ZEB1 is a major driver of melanoma cell plasticity, driving drug adaptation and phenotypic resistance to MAPKi.
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Antineoplásicos/farmacología , Plasticidad de la Célula , Resistencia a Medicamentos , Melanocitos/efectos de los fármacos , Melanocitos/fisiología , Inhibidores de Proteínas Quinasas/farmacología , Homeobox 1 de Unión a la E-Box con Dedos de Zinc/metabolismo , Adaptación Fisiológica , Línea Celular Tumoral , Humanos , Melanoma/tratamiento farmacológico , Melanoma/fisiopatologíaRESUMEN
The TWIST1 embryonic transcription factor displays biphasic functions during the course of carcinogenesis. It facilitates the escape of cells from oncogene-induced fail-safe programs (senescence, apoptosis) and their consequent neoplastic transformation. Additionally, it promotes the epithelial-to-mesenchymal transition and the initiation of the metastatic spread of cancer cells. Interestingly, cancer cells recurrently remain dependent on TWIST1 for their survival and/or proliferation, making TWIST1 their Achilles' heel. TWIST1 has been reported to form either homodimeric or heterodimeric complexes mainly in association with the E bHLH class I proteins. These complexes display distinct, sometimes even antagonistic, functions during development and unequal prometastatic functions in prostate cancer cells. Using a tethered dimer strategy, we successively assessed the ability of TWIST1 dimers to cooperate with an activated version of RAS in human mammary epithelial cell transformation, to provide mice with the ability to spontaneously develop breast tumors, and lastly to maintain a senescence program at a latent state in several breast cancer cell lines. We demonstrate that the TWIST1-E12 complex, unlike the homodimer, is an oncogenic form of TWIST1 in mammary epithelial cells and that efficient binding of both partners is a prerequisite for its activity. The detection of the heterodimer in human premalignant lesions by a proximity ligation assay, at a stage preceding the initiation of the metastatic cascade, is coherent with such an oncogenic function. TWIST1-E protein heterodimeric complexes may thus constitute the main active forms of TWIST1 with regard to senescence inhibition over the time course of breast tumorigenesis.
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Transformación Celular Neoplásica/metabolismo , Células Epiteliales/metabolismo , Glándulas Mamarias Humanas/metabolismo , Factor de Transcripción 3/metabolismo , Proteína 1 Relacionada con Twist/metabolismo , Línea Celular Tumoral , Proliferación Celular , Senescencia Celular/genética , Células Epiteliales/patología , Expresión Génica , Humanos , Glándulas Mamarias Humanas/patología , Mutación , Lesiones Precancerosas/genética , Lesiones Precancerosas/metabolismo , Lesiones Precancerosas/patología , Unión Proteica , Multimerización de Proteína , Factor de Transcripción 3/genética , Proteína 1 Relacionada con Twist/genéticaRESUMEN
The TWIST1 bHLH transcription factor controls embryonic development and cancer processes. Although molecular and genetic analyses have provided a wealth of data on the role of bHLH transcription factors, very little is known on the molecular mechanisms underlying their binding affinity to the E-box sequence of the promoter. Here, we used an in silico model of the TWIST1/E12 (TE) heterocomplex and performed molecular dynamics (MD) simulations of its binding to specific (TE-box) and modified E-box sequences. We focused on (i) active E-box and inactive E-box sequences, on (ii) modified active E-box sequences, as well as on (iii) two box sequences with modified adjacent bases the AT- and TA-boxes. Our in silico models were supported by functional in vitro binding assays. This exploration highlighted the predominant role of protein side-chain residues, close to the heart of the complex, at anchoring the dimer to DNA sequences, and unveiled a shift towards adjacent ((-1) and (-1*)) bases and conserved bases of modified E-box sequences. In conclusion, our study provides proof of the predictive value of these MD simulations, which may contribute to the characterization of specific inhibitors by docking approaches, and their use in pharmacological therapies by blocking the tumoral TWIST1/E12 function in cancers.
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Elementos E-Box , Modelos Moleculares , Factor de Transcripción 3/química , Proteína 1 Relacionada con Twist/química , Secuencia de Bases , Sitios de Unión , Línea Celular , Humanos , Enlace de Hidrógeno , Conformación Molecular , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Unión Proteica , Factor de Transcripción 3/metabolismo , Proteína 1 Relacionada con Twist/metabolismoRESUMEN
The transcription accessory factor TIF1γ/TRIM33/RFG7/PTC7/Ectodermin functions as a tumor suppressor that promotes development and cellular differentiation. However, its precise function in cancer has been elusive. In the present study, we report that TIF1γ inactivation causes cells to accumulate chromosomal defects, a hallmark of cancer, due to attenuations in the spindle assembly checkpoint and the post-mitotic checkpoint. TIF1γ deficiency also caused a loss of contact growth inhibition and increased anchorage-independent growth in vitro and in vivo. Clinically, reduced TIF1γ expression in human tumors correlated with an increased rate of genomic rearrangements. Overall, our work indicates that TIF1γ exerts its tumor-suppressive functions in part by promoting chromosomal stability.
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Puntos de Control del Ciclo Celular/genética , Inestabilidad Cromosómica , Regulación Neoplásica de la Expresión Génica , Mitosis/genética , Neoplasias/genética , Neoplasias/metabolismo , Factores de Transcripción/metabolismo , Animales , Carcinoma in Situ , Línea Celular Tumoral , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/metabolismo , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Regulación hacia Abajo , Transición Epitelial-Mesenquimal/genética , Silenciador del Gen , Humanos , Ratones , Ratones Noqueados , Neoplasias/patología , Ploidias , Huso Acromático/metabolismoAsunto(s)
Antineoplásicos/farmacología , Camptotecina/análogos & derivados , Senescencia Celular/efectos de los fármacos , Neoplasias Colorrectales/patología , Resistencia a Antineoplásicos/fisiología , Proteína 1 de la Secuencia de Leucemia de Células Mieloides/metabolismo , Animales , Humanos , MasculinoRESUMEN
INTRODUCTION: Tumor-initiating cells (TICs), aka "cancer stem cells", are believed to fuel tumors and to sustain therapy resistance and systemic metastasis. Breast cancer is the first human carcinoma in which a subpopulation of cells displaying a specific CD44+/CD24-/low/ESA+ antigenic phenotype was found to have TIC properties. However, CD44+/CD24-/low/ESA+ is not a universal marker phenotype of TICs in all breast cancer subtypes. The aim of this study was to identify novel antigens with which to isolate the TIC population of the basal-A/basal-like breast cancer cell lines. METHODS: We used polychromatic flow-cytometry to characterize the cell surface of several breast cancer cell lines that may represent different tumor molecular subtypes. We next used fluorescence-activated cell sorting to isolate the cell subpopulations of interest from the cell lines. Finally, we explored the stem-like and tumorigenic properties of the sorted cell subpopulations using complementary in vitro and in vivo approaches: mammosphere formation assays, soft-agar colony assays, and tumorigenic assays in NOD/SCID mice. RESULTS: The CD44+/CD24+ subpopulation of the BRCA1-mutated basal-A/basal-like cell line HCC1937 is enriched in several stemness markers, including the ABCG2 transporter (i.e., the CD338 antigen). Consistently, CD338-expressing cells were also enriched in CD24 expression, suggesting that coexpression of these two antigenic markers may segregate TICs in this cell line. In support of ABCG2 expression in TICs, culturing of HCC1937 cells in ultra-low adherent conditions to enrich them in precursor/stem-cells resulted in an increase in CD338-expressing cells. Furthermore, CD338-expressing cells, unlike their CD338-negative counterparts, displayed stemness and transformation potential, as assessed in mammosphere and colony formation assays. Lastly, CD338-expressing cells cultured in ultra-low adherent conditions maintained the expression of CD326/EpCAM and CD49f/α6-integrin, which is a combination of antigens previously assigned to luminal progenitors. CONCLUSION: Collectively, our data suggest that CD338 expression is specific to the tumor-initiating luminal progenitor subpopulation of BRCA1-mutated cells and is a novel antigen with which to sort this subpopulation.
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Transportadoras de Casetes de Unión a ATP/metabolismo , Proteína BRCA1/metabolismo , Neoplasias de la Mama/patología , Citometría de Flujo , Proteínas de Neoplasias/metabolismo , Células Madre Neoplásicas/patología , Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 2 , Animales , Antígeno CD24/metabolismo , Adhesión Celular , Línea Celular Tumoral , Membrana Celular/metabolismo , Proliferación Celular , Transformación Celular Neoplásica/metabolismo , Transformación Celular Neoplásica/patología , Femenino , Técnicas de Silenciamiento del Gen , Humanos , Ratones Endogámicos NOD , Ratones SCID , Esferoides Celulares/patologíaRESUMEN
The transcription factor TWIST1 induces epithelial-mesenchymal transition and/or escape to the oncogenic-induced failsafe program, facilitating the intravasation of breast cancer cells in the systemic circulation and their dissemination to the lungs. Its involvement in breast cancer bone metastasis is unknown. To address this question, human osteotropic MDA-MB-231/B02 breast cancer cells were stably transfected with a Tet-inducible vector encoding for TWIST1, whose expression was specifically repressed in the presence of doxycycline (dox). The intra-arterial inoculation of transfectants expressing TWIST1 in immunodeficient mice substantially increased the extent of osteolytic lesions in these animals, being 50% larger than that of animals bearing mock-transfected tumors, as determined by radiography. This difference was accompanied by a sharp reduction of the bone volume (indicating a higher bone destruction) and a twofold increase in the tumor volume compared with mice bearing mock-transfected tumors, as determined by histomorphometry. Importantly, the suppression of TWIST1 expression in MDA-MB-231/B02 cells in the presence of dox abolished the stimulatory effect of TWIST1 on bone metastasis formation in vivo. Additionally, examination of the bone marrow from untreated and dox-treated animals on day 7 after tumor cell inoculation, at which time there was no evidence of radiographic osteolytic lesions, revealed that the number of tumor cell colonies that were recovered from the bone marrow of untreated mice was dramatically increased compared with that of dox-fed animals. In vitro, TWIST1 expression promoted tumor cell invasion and enhanced microRNA 10b (miR-10b) expression, a proinvasive factor, but was dispensable for growth of tumor cells. In vivo, the repression of miR-10b substantially decreased the presence of TWIST1-expressing breast cancer cells in the bone marrow. Overall, these results establish that TWIST1 facilitates breast cancer bone metastasis formation through a mechanism dependent of miR-10b, which leads to increase tumor burden and bone destruction.
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Neoplasias Óseas/secundario , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Regulación Neoplásica de la Expresión Génica , Proteínas Nucleares/genética , Proteína 1 Relacionada con Twist/genética , Animales , Western Blotting , Diferenciación Celular , Línea Celular Tumoral , Doxiciclina/farmacología , Femenino , Citometría de Flujo , Técnica del Anticuerpo Fluorescente , Humanos , Ratones , Ratones Endogámicos BALB C , MicroARNs/genética , Metástasis de la Neoplasia , Proteínas Nucleares/metabolismo , Osteoclastos/citología , Proteína 1 Relacionada con Twist/metabolismoRESUMEN
By fostering cell commitment to the epithelial-to-mesenchymal transition (EMT), SNAIL proteins endow cells with motility, thereby favoring the metastatic spread of tumor cells. Whether the phenotypic change additionally facilitates tumor initiation has never been addressed. Here we demonstrate that when a SNAIL protein is ectopically produced in non-transformed mammary epithelial cells, the cells are protected from anoikis and proliferate under low-adherence conditions: a hallmark of cancer cells. The three SNAIL proteins show unequal oncogenic potential, strictly correlating with their ability to promote EMT. SNAIL3 especially behaves as a poor EMT-inducer comforting the concept that the transcription factor functionally diverges from its two related proteins.
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Transformación Celular Neoplásica/patología , Células Epiteliales/metabolismo , Células Epiteliales/patología , Transición Epitelial-Mesenquimal , Glándulas Mamarias Humanas/patología , Factores de Transcripción/metabolismo , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Adhesión Celular/genética , Supervivencia Celular/genética , Transformación Celular Neoplásica/genética , Transición Epitelial-Mesenquimal/genética , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Factores de Transcripción de la Familia Snail , Telomerasa/metabolismo , Factores de Transcripción/genéticaRESUMEN
The basic helix-loop-helix (bHLH) transcription factor TWIST1 is essential to embryonic development, and hijacking of its function contributes to the development of numerous cancer types. It forms either a homodimer or a heterodimeric complex with an E2A or HAND partner. These functionally distinct complexes display sometimes antagonistic functions during development, so that alterations in the balance between them lead to pronounced morphological alterations, as observed in mice and in Saethre-Chotzen syndrome patients. We, here, describe the structures of TWIST1 bHLH-DNA complexes produced in silico through molecular dynamics simulations. We highlight the determinant role of the interhelical loops in maintaining the TWIST1-DNA complex structures and provide a structural explanation for the loss of function associated with several TWIST1 mutations/insertions observed in Saethre-Chotzen syndrome patients. An animated interactive 3D complement (I3DC) is available in Proteopedia at http://proteopedia.org/w/Journal:JBSD:27.
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Secuencias Hélice-Asa-Hélice , Proteínas Nucleares/química , Proteína 1 Relacionada con Twist/química , Acrocefalosindactilia/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/química , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/ultraestructura , Cristalografía por Rayos X , ADN/química , Humanos , Ratones , Simulación de Dinámica Molecular , Mutación , Proteína MioD/química , Proteína MioD/ultraestructura , Proteínas Nucleares/genética , Unión Proteica/genética , Multimerización de Proteína , Alineación de Secuencia , Factor de Transcripción 3/química , Factor de Transcripción 3/ultraestructura , Proteína 1 Relacionada con Twist/genéticaRESUMEN
Aberrant expression of embryonic epithelial-mesenchymal transition-inducing transcription factors (EMT-TFs) in epithelial cells triggers EMT, neoplastic transformation, stemness, and metastatic dissemination. We found that regulation and functions of EMT-TFs are different in malignant melanoma. SNAIL2 and ZEB2 transcription factors are expressed in normal melanocytes and behave as tumor-suppressor proteins by activating an MITF-dependent melanocyte differentiation program. In response to NRAS/BRAF activation, EMT-TF network undergoes a profound reorganization in favor of TWIST1 and ZEB1. This reversible switch cooperates with BRAF in promoting dedifferentiation and neoplastic transformation of melanocytes. We detected EMT-TF reprogramming in late-stage melanoma in association with enhanced phospho-ERK levels. This switch results in E-cadherin loss, enhanced invasion, and constitutes an independent factor of poor prognosis in melanoma patients.
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Transición Epitelial-Mesenquimal , Regulación Neoplásica de la Expresión Génica , Melanoma/metabolismo , Animales , Antígenos CD , Cadherinas/metabolismo , Diferenciación Celular , Progresión de la Enfermedad , Supervivencia sin Enfermedad , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Femenino , Proteínas de Homeodominio/metabolismo , Humanos , Sistema de Señalización de MAP Quinasas , Melanocitos/citología , Ratones , Ratones Desnudos , Proteínas Nucleares/metabolismo , Fosforilación , Pronóstico , Factores de Transcripción/metabolismo , Proteína 1 Relacionada con Twist/metabolismo , Homeobox 1 de Unión a la E-Box con Dedos de ZincRESUMEN
Expression of developmental genes Twist1 and Twist2 is reactivated in many human tumors. Among their oncogenic activities, induction of epithelial to mesenchymal transition is believed to increase cell motility and invasiveness and may be related to acquisition of cancer stem cell phenotype. In addition, Twist proteins promote malignant conversion by overriding two oncogene-induced failsafe programs: senescence and apoptosis. Reactive oxygen species (ROS) are also important mediators of apoptosis, senescence and motility and are tightly linked to disease, notably to cancer. We report here that Twist factors and ROS are functionally linked. In wild type cells both Twist1 and Twist2 exhibit antioxidant properties. We show that Twist-driven modulation of oncogene-induced apoptosis is linked to its effects on oxidative stress. Finally, we identify several targets that mediate Twist antioxidant activity. These findings unveil a new function of Twist factors that could be important in explaining their pleiotropic role during carcinogenesis.