RESUMO
Studies have suggested involvement of interleukin 17 (IL-17) in autoimmune diseases, although its effect on B cell biology has not been clearly established. Here we demonstrate that IL-17 alone or in combination with B cell-activating factor controlled the survival and proliferation of human B cells and their differentiation into immunoglobulin-secreting cells. This effect was mediated mainly through the nuclear factor-kappaB-regulated transcription factor Twist-1. In support of the relevance of our observations and the potential involvement of IL-17 in B cell biology, we found that the serum of patients with systemic lupus erythematosus had higher concentrations of IL-17 than did the serum of healthy people and that IL-17 abundance correlated with the disease severity of systemic lupus erythematosus.
Assuntos
Fator Ativador de Células B/farmacologia , Linfócitos B/efeitos dos fármacos , Interleucina-17/sangue , Interleucina-17/farmacologia , Lúpus Eritematoso Sistêmico/sangue , Antígenos CD19/metabolismo , Apoptose/efeitos dos fármacos , Linfócitos B/citologia , Linfócitos B/metabolismo , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Feminino , Humanos , Immunoblotting , Imunoglobulinas/metabolismo , Interleucina-17/genética , Lúpus Eritematoso Sistêmico/patologia , Masculino , Antígenos de Histocompatibilidade Menor , NF-kappa B/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de Tempo , Proteína 1 Relacionada a Twist/genética , Proteína 1 Relacionada a Twist/metabolismoRESUMO
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.
Assuntos
Elementos E-Box , Modelos Moleculares , Fator 3 de Transcrição/química , Proteína 1 Relacionada a Twist/química , Sequência de Bases , Sítios de Ligação , Linhagem Celular , Humanos , Ligação de Hidrogênio , Conformação Molecular , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Ligação Proteica , Fator 3 de Transcrição/metabolismo , Proteína 1 Relacionada a Twist/metabolismoRESUMO
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.
Assuntos
Simulação de Dinâmica Molecular , Proteínas Nucleares/química , Proteínas Nucleares/genética , Mutação Puntual , Fator 3 de Transcrição/química , Proteína 1 Relacionada a Twist/química , Proteína 1 Relacionada a Twist/genética , Sequência de Aminoácidos , Animais , Arginina/química , Arginina/genética , Simulação por Computador , Cristalografia por Raios X , Glicina/química , Glicina/genética , Humanos , Camundongos , Fosforilação , Conformação Proteica , Multimerização Proteica , Homologia de Sequência , Fator 3 de Transcrição/genéticaRESUMO
The epithelial-mesenchymal transition (EMT) is an embryonic transdifferentiation process consisting of conversion of polarized epithelial cells to motile mesenchymal ones. EMT-inducing transcription factors are aberrantly expressed in multiple tumor types and are known to favor the metastatic dissemination process. Supporting oncogenic activity within primary lesions, the TWIST and ZEB proteins can prevent cells from undergoing oncogene-induced senescence and apoptosis by abolishing both p53- and RB-dependent pathways. Here we show that they also downregulate PP2A phosphatase activity and efficiently cooperate with an oncogenic version of H-RAS in malignant transformation of human mammary epithelial cells. Thus, by down-regulating crucial tumor suppressor functions, EMT inducers make cells particularly prone to malignant conversion. Importantly, by analyzing transformed cells generated in vitro and by characterizing novel transgenic mouse models, we further demonstrate that cooperation between an EMT inducer and an active form of RAS is sufficient to trigger transformation of mammary epithelial cells into malignant cells exhibiting all the characteristic features of claudin-low tumors, including low expression of tight and adherens junction genes, EMT traits, and stem cell-like characteristics. Claudin-low tumors are believed to be the most primitive breast malignancies, having arisen through transformation of an early epithelial precursor with inherent stemness properties and metaplastic features. Challenging this prevailing view, we propose that these aggressive tumors arise from cells committed to luminal differentiation, through a process driven by EMT inducers and combining malignant transformation and transdifferentiation.
Assuntos
Neoplasias da Mama , Transformação Celular Neoplásica , Claudinas , Transição Epitelial-Mesenquimal , Glândulas Mamárias Humanas/metabolismo , Proteína Fosfatase 2 , Proteína 1 Relacionada a Twist/genética , Animais , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Diferenciação Celular , Linhagem Celular , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Claudinas/genética , Claudinas/metabolismo , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Transição Epitelial-Mesenquimal/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Genes ras , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Humanos , Glândulas Mamárias Animais/citologia , Glândulas Mamárias Animais/metabolismo , Glândulas Mamárias Humanas/citologia , Camundongos , Camundongos Transgênicos , Proteína Fosfatase 2/antagonistas & inibidores , Proteína Fosfatase 2/metabolismo , Proteína do Retinoblastoma/metabolismo , Telomerase/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Proteína 1 Relacionada a Twist/metabolismo , Homeobox 1 de Ligação a E-box em Dedo de ZincoRESUMO
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.
Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Proteína BRCA1/metabolismo , Neoplasias da Mama/patologia , Citometria de Fluxo , Proteínas de Neoplasias/metabolismo , Células-Tronco Neoplásicas/patologia , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Animais , Antígeno CD24/metabolismo , Adesão Celular , Linhagem Celular Tumoral , Membrana Celular/metabolismo , Proliferação de Células , Transformação Celular Neoplásica/metabolismo , Transformação Celular Neoplásica/patologia , Feminino , Técnicas de Silenciamento de Genes , Humanos , Camundongos Endogâmicos NOD , Camundongos SCID , Esferoides Celulares/patologiaRESUMO
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.
Assuntos
Benzimidazóis , MAP Quinases Reguladas por Sinal Extracelular , Fator 88 de Diferenciação Mieloide , Fator 88 de Diferenciação Mieloide/metabolismo , Fator 88 de Diferenciação Mieloide/genética , Humanos , Animais , Camundongos , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Linhagem Celular Tumoral , Benzimidazóis/farmacologia , Apoptose/efeitos dos fármacos , Morte Celular Imunogênica/efeitos dos fármacos , Neoplasias/imunologia , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Neoplasias/metabolismo , Feminino , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/imunologia , Ensaios Antitumorais Modelo de Xenoenxerto , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêuticoRESUMO
The epithelial to mesenchymal transition (EMT) is a latent embryonic process which can be aberrantly reactivated during tumor progression. It is generally viewed as one of the main forces driving metastatic dissemination, by providing cells with invasive and motility capabilities. The aberrant reactivation of embryonic EMT inducers has now been additionally linked to escape from senescence and apoptosis, which suggests a role in tumor initiation. This oncogenic potential relies on the ability of EMT inducers to neutralize both the RB and p53 oncosuppressive pathways. RB and p53 have recently been described as key factors in the maintenance of epithelial morphology, which suggests an unexpected and intimate crosstalk between EMT and the corresponding safety programs. In this review, we attempt to understand how these two cell processes are interlinked and might facilitate cell transformation and tumor initiation.
Assuntos
Transição Epitelial-Mesenquimal , Evasão Tumoral , Progressão da Doença , Humanos , Neoplasias/patologiaRESUMO
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.
RESUMO
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.
RESUMO
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.
RESUMO
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.
RESUMO
The MYND domain (named after myeloid translocation protein 8, Nervy, and DEAF-1) is a conserved zinc binding domain. It is defined by seven conserved cysteine residues and a single histidine residue that are arranged in a C4-C2HC consensus. MYND domains exist in a large number of proteins that play important roles in development or are associated with cancers and have been shown to mediate protein-protein interactions, mainly in the context of transcriptional regulation. We have determined the three-dimensional structure of the MYND domain from human deformed epidermal autoregulatory factor-1 (DEAF-1). The structure reveals a novel zinc binding fold, in which the C4-C2HC motif forms two sequential zinc binding sites. The first and second zinc binding modules comprise a small beta hairpin and two short alpha helices, respectively. The sequential topology of the two zinc binding sites is distinct from the cross-brace PHD and RING finger folds but has some resemblance to LIM domains. The structure reveals that the MYND domain is a novel member of the treble-clef family of zinc binding domains. The MYND domains of BS69 and BOP bind ligands comprising a PXLXP peptide motif. On the basis of the solution structure of the DEAF-1 MYND domain we calculated a homology model of the MYND domain of the BS69 tumor suppressor. A mutational analysis of the BS69 MYND domain indicates that positively charged residues located on one face of its MYND domain are crucial for the molecular interactions of BS69. Different binding specificities of MYND domains may depend on distinct surface charge distributions.
Assuntos
Proteínas Nucleares/química , Proteínas Nucleares/metabolismo , Sequência de Aminoácidos , Proteínas de Ligação a DNA , Humanos , Ligantes , Dados de Sequência Molecular , Mutação , Proteínas Nucleares/genética , Fragmentos de Peptídeos/metabolismo , Ligação Proteica , Dobramento de Proteína , Estrutura Terciária de Proteína , Homologia de Sequência de Aminoácidos , Fatores de Transcrição , Zinco/metabolismoRESUMO
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.
Assuntos
Neoplasias da Mama/genética , Carcinoma/genética , Diferenciação Celular/genética , Células Epiteliais/metabolismo , Regulação Neoplásica da Expressão Gênica , Instabilidade Genômica/genética , Metionina Sulfóxido Redutases/genética , Células-Tronco/metabolismo , Homeobox 1 de Ligação a E-box em Dedo de Zinco/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Neoplasias da Mama/metabolismo , Carcinoma/metabolismo , Linhagem Celular Tumoral , Transformação Celular Neoplásica/genética , Imunoprecipitação da Cromatina , Dano ao DNA , Células Epiteliais/citologia , Feminino , Citometria de Fluxo , Imunofluorescência , Perfilação da Expressão Gênica , Humanos , Immunoblotting , Glândulas Mamárias Humanas/citologia , Metionina Sulfóxido Redutases/metabolismo , Camundongos Endogâmicos NOD , Pessoa de Meia-Idade , Espécies Reativas de Oxigênio , Reação em Cadeia da Polimerase em Tempo Real , Análise de Sequência de DNA , Células-Tronco/citologia , Análise Serial de Tecidos , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Adulto Jovem , Homeobox 1 de Ligação a E-box em Dedo de Zinco/metabolismoRESUMO
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.
Assuntos
Transformação Celular Neoplásica/metabolismo , Células Epiteliais/metabolismo , Glândulas Mamárias Humanas/metabolismo , Fator 3 de Transcrição/metabolismo , Proteína 1 Relacionada a Twist/metabolismo , Linhagem Celular Tumoral , Proliferação de Células , Senescência Celular/genética , Células Epiteliais/patologia , Expressão Gênica , Humanos , Glândulas Mamárias Humanas/patologia , Mutação , Lesões Pré-Cancerosas/genética , Lesões Pré-Cancerosas/metabolismo , Lesões Pré-Cancerosas/patologia , Ligação Proteica , Multimerização Proteica , Fator 3 de Transcrição/genética , Proteína 1 Relacionada a Twist/genéticaRESUMO
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.
Assuntos
Antineoplásicos/farmacologia , Plasticidade Celular , Resistência a Medicamentos , Melanócitos/efeitos dos fármacos , Melanócitos/fisiologia , Inibidores de Proteínas Quinases/farmacologia , Homeobox 1 de Ligação a E-box em Dedo de Zinco/metabolismo , Adaptação Fisiológica , Linhagem Celular Tumoral , Humanos , Melanoma/tratamento farmacológico , Melanoma/fisiopatologiaRESUMO
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.
Assuntos
Pontos de Checagem do Ciclo Celular/genética , Instabilidade Cromossômica , Regulação Neoplásica da Expressão Gênica , Mitose/genética , Neoplasias/genética , Neoplasias/metabolismo , Fatores de Transcrição/metabolismo , Animais , Carcinoma in Situ , Linhagem Celular Tumoral , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Regulação para Baixo , Transição Epitelial-Mesenquimal/genética , Inativação Gênica , Humanos , Camundongos , Camundongos Knockout , Neoplasias/patologia , Ploidias , Fuso Acromático/metabolismoRESUMO
The LIM only protein Lmo2 plays an important role in hematopoiesis and leukemogenesis. Lmo2 acts as a bridging molecule between components of hematopoietic gene regulatory protein complexes. We used the yeast two-hybrid system to identify novel Lmo2 interacting proteins and found that the AF6 protein binds to Lmo2. AF6 is a recurrent fusion partner of MLL, the human homolog of Drosophila trithorax chromatin remodeling protein that is involved in childhood leukemia and mixed lineage leukemia. Our data support the notion that recurrent fusion partners of chimeric MLL proteins recruit hematopoietic gene regulatory complexes.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas de Drosophila , Cinesinas/metabolismo , Metaloproteínas/metabolismo , Miosinas/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Proto-Oncogenes , Fatores de Transcrição , Proteínas Adaptadoras de Transdução de Sinal , Animais , Linhagem Celular , Proteínas de Ligação a DNA/genética , Histona-Lisina N-Metiltransferase , Humanos , Células Jurkat , Cinesinas/genética , Proteínas com Domínio LIM , Metaloproteínas/genética , Proteína de Leucina Linfoide-Mieloide , Miosinas/genética , Proteínas Proto-Oncogênicas/genética , Codorniz , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismoAssuntos
Movimento Celular/fisiologia , Metástase Neoplásica/fisiopatologia , Humanos , Metástase Neoplásica/genética , Metástase Neoplásica/patologia , Proteínas Nucleares/genética , Proteínas Nucleares/fisiologia , Proteína 1 Relacionada a Twist/genética , Proteína 1 Relacionada a Twist/fisiologiaRESUMO
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.