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The dynamic crosstalk between tumor and stromal cells is a major determinant of cancer aggressiveness. The tumor-suppressor DAB2IP (Disabled homolog 2 interacting protein) plays an important role in this context, since it modulates cell responses to multiple extracellular inputs, including inflammatory cytokines and growth factors. DAB2IP is a RasGAP and negatively controls Ras-dependent mitogenic signals. In addition, it modulates other major oncogenic pathways, including TNFα/NF-κB, WNT/ß-catenin, PI3K/AKT, and androgen receptor signaling. In line with its tumor-suppressive role, DAB2IP is frequently inactivated in cancer by transcriptional and post-transcriptional mechanisms, including promoter methylation, microRNA-mediated downregulation, and protein-protein interactions. Intriguingly, some observations suggest that downregulation of DAB2IP in cells of the tumor stroma could foster establishment of a pro-metastatic microenvironment. This review summarizes recent insights into the tumor-suppressive functions of DAB2IP and the consequences of its inactivation in cancer. In particular, we explore potential approaches aimed at reactivating DAB2IP, or augmenting its expression levels, as a novel strategy in cancer treatment. We suggest that reactivation or upregulation of DAB2IP would concurrently attenuate multiple oncogenic pathways in both cancer cells and the tumor microenvironment, with implications for improved treatment of a broad spectrum of tumors.
Assuntos
Neoplasias , Proteínas Ativadoras de ras GTPase , Humanos , Proteínas Ativadoras de ras GTPase/metabolismo , Proteínas Ativadoras de ras GTPase/genética , Neoplasias/metabolismo , Neoplasias/patologia , Neoplasias/tratamento farmacológico , Neoplasias/genética , Animais , Transdução de SinaisRESUMO
Human osteosarcoma (OS) is a relatively rare malignancy preferentially affecting long body bones which prognosis is often poor also due to the lack of effective therapies. Clinical management of this cancer basically relies on surgical removal of primary tumor coupled with radio/chemotherapy. Unfortunately, most osteosarcoma cells are resistant to conventional therapy, with the undergoing epithelial-mesenchymal transition (EMT) giving rise to gene expression reprogramming, thus increasing cancer cell invasiveness and metastatic potential. Alternative clinical approaches are thus urgently needed. In this context, the recently described ferroptotic cell death represents an attractive new strategy to efficiently kill cancer cells, since most chemoresistant and mesenchymal-shaped tumors display high susceptibility to pro-ferroptotic compounds. However, cancer cells have also evolved anti-ferroptotic strategies, which somehow sustain their survival upon ferroptosis induction. Indeed, here we show that osteosarcoma cell lines display heterogeneous sensitivity to ferroptosis execution, correlating with the mesenchymal phenotype, which is consistently affected by the expression of the well-known anti-ferroptotic factor ferroptosis suppressor protein 1 (FSP1). Interestingly, inhibiting the activity or expression of FSP1 restores cancer cell sensitivity to ferroptosis. Moreover, we also found that: i) AKRs might also contribute to resistance; ii) NRF2 enhances FSP1 expression upon ferroptosis induction; while iii) p53 contributes to the regulation of FSP1 basal expression in OS cells.In conclusion, FSP1 expression can potentially be used as a valuable predictive marker of OS sensitivity to ferroptosis and as a new potential therapeutic target.
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External and internal mechanical forces modulate cell morphology, movement, proliferation and metabolism, and represent crucial inputs for tissue homeostasis. The transcriptional regulators YAP and TAZ are important effectors of mechanical signaling and are frequently activated in solid tumors, correlating with metastasis, chemoresistance, and shorter patient survival. YAP/TAZ activity is controlled by various pathways that sense cell shape, polarity, contacts, and mechanical tension. In tumors, aberrant YAP/TAZ activation may result from cancer-related alterations of such regulatory networks. The tumor suppressor DAB2IP is a Ras-GAP and scaffold protein that negatively modulates multiple oncogenic pathways and is frequently downregulated or inactivated in solid tumors. Here, we provide evidence that DAB2IP expression is sustained by cell confluency. We also find that DAB2IP depletion in confluent cells alters their morphology, reducing cell packing while increasing cell stiffness. Finally, we find that DAB2IP depletion in confluent cells favors YAP/TAZ nuclear localization and transcriptional activity, while its ectopic expression in subconfluent cells increases YAP/TAZ retention in the cytoplasm. Together, these data suggest that DAB2IP may function as a sensor of cell interactions, contributing to dampening cellular responses to oncogenic inputs in confluent cells and that DAB2IP loss-of-function would facilitate YAP/TAZ activation in intact epithelia, accelerating oncogenic transformation.
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Cancer cells within tumor masses are chronically exposed to stress caused by nutrient deprivation, oxygen limitation, and high metabolic demand. They also accumulate hundreds of mutations, potentially generating aberrant proteins that can induce proteotoxic stress. Finally, cancer cells are exposed to various damages during chemotherapy. In a growing tumor, transformed cells eventually adapt to these conditions, eluding the death-inducing outcomes of signaling cascades triggered by chronic stress. One such extreme outcome is ferroptosis, a form of iron-dependent non-apoptotic cell death mediated by lipid peroxidation. Not surprisingly, the tumor suppressor p53 is involved in this process, with evidence suggesting that it acts as a pro-ferroptotic factor and that its ferroptosis-inducing activity may be relevant for tumor suppression. Missense alterations of the TP53 gene are extremely frequent in human cancers and give rise to mutant p53 proteins (mutp53) that lose tumor suppressive function and can acquire powerful oncogenic activities. This suggests that p53 mutation provides a selective advantage during tumor progression, raising interesting questions on the impact of p53 mutant proteins in modulating the ferroptotic process. Here, we explore the role of p53 and its cancer-related mutants in ferroptosis, using a perspective centered on the resistance/sensitivity of cancer cells to exogenous and endogenous stress conditions that can trigger ferroptotic cell death. We speculate that an accurate molecular understanding of this particular axis may improve cancer treatment options.
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Extracellular vesicle (EV) mediated communication has recently been proposed as one of the pivotal routes in the development of cancer metastasis. EVs are nano-sized vesicles swapped between cells, carrying a biologically active content that can promote tumor-induced immune suppression, metastasis and angiogenesis. Thus, EVs constitute a potential target in cancer therapy. However, their role in triggering the premetastatic niche and in tumor spreading is still unclear. Here, we focused on the EV ability to modulate the biomechanical properties of target cells, known to play a crucial role in metastatic spreading. To this purpose, we isolated and thoroughly characterized triple-negative breast cancer (TNBC)-derived small EVs. We then evaluated variations in the mechanical properties (cell stiffness, cytoskeleton/nuclear/morphology and Yap activity rearrangements) of non-metastatic breast cancer MCF7 cells upon EV treatment. Our results suggest that TNBC-derived small EVs are able to directly modify MCF7 cells by inducing a decrease in cell stiffness, rearrangements in cytoskeleton, focal adhesions and nuclear/cellular morphology, and an increase in Yap downstream gene expression. Testing the biomechanical response of cells after EV addition might represent a new functional assay in metastatic cancer framework that can be exploited for future application both in diagnosis and in therapy.
Assuntos
Vesículas Extracelulares , Neoplasias de Mama Triplo Negativas , Fenômenos Biomecânicos , Vesículas Extracelulares/metabolismo , Humanos , Células MCF-7 , Neoplasias de Mama Triplo Negativas/patologiaRESUMO
Acquisition of cell-associated tumor antigens by type 1 dendritic cells (cDC1) is essential to induce and sustain tumor specific CD8+ T cells via cross-presentation. Here we show that capture and engulfment of cell associated antigens by tissue resident lung cDC1 is inhibited during progression of mouse lung tumors. Mechanistically, loss of phagocytosis is linked to tumor-mediated downregulation of the phosphatidylserine receptor TIM4, that is highly expressed in normal lung resident cDC1. TIM4 receptor blockade and conditional cDC1 deletion impair activation of tumor specific CD8+ T cells and promote tumor progression. In human lung adenocarcinomas, TIM4 transcripts increase the prognostic value of a cDC1 signature and predict responses to PD-1 treatment. Thus, TIM4 on lung resident cDC1 contributes to immune surveillance and its expression is suppressed in advanced tumors.
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Antígenos de Neoplasias/imunologia , Células Dendríticas/imunologia , Neoplasias Pulmonares/imunologia , Proteínas de Membrana/imunologia , Adenocarcinoma/genética , Adenocarcinoma/imunologia , Animais , Antígenos de Neoplasias/genética , Linfócitos T CD8-Positivos/imunologia , Apresentação Cruzada , Humanos , Vigilância Imunológica , Pulmão/imunologia , Neoplasias Pulmonares/genética , Proteínas de Membrana/genética , CamundongosRESUMO
The Ras pathway is frequently deregulated in cancer, actively contributing to tumor development and progression. Oncogenic activation of the Ras pathway is commonly due to point mutation of one of the three Ras genes, which occurs in almost one third of human cancers. In the absence of Ras mutation, the pathway is frequently activated by alternative means, including the loss of function of Ras inhibitors. Among Ras inhibitors, the GTPase-Activating Proteins (RasGAPs) are major players, given their ability to modulate multiple cancer-related pathways. In fact, most RasGAPs also have a multi-domain structure that allows them to act as scaffold or adaptor proteins, affecting additional oncogenic cascades. In cancer cells, various mechanisms can cause the loss of function of Ras inhibitors; here, we review the available evidence of RasGAP inactivation in cancer, with a specific focus on the mechanisms. We also consider extracellular inputs that can affect RasGAP levels and functions, implicating that specific conditions in the tumor microenvironment can foster or counteract Ras signaling through negative or positive modulation of RasGAPs. A better understanding of these conditions might have relevant clinical repercussions, since treatments to restore or enhance the function of RasGAPs in cancer would help circumvent the intrinsic difficulty of directly targeting the Ras protein.
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Glucocorticoids (GCs) are commonly used as therapeutic agents for immune-mediated diseases and leukemia. However, considerable inter-individual differences in efficacy have been reported. Several reports indicate that the inhibitor of mTOR rapamycin can reverse GC resistance, but the molecular mechanism involved in this synergistic effect has not been fully defined. In this context, we explored the differential miRNA expression in a GC-resistant CCRF-CEM cell line after treatment with rapamycin alone or in co-treatment with methylprednisolone (MP). The expression analysis identified 70, 99 and 96 miRNAs that were differentially expressed after treatment with MP, rapamycin and their combination compared to non-treated controls, respectively. Two pathways were exclusively altered as a result of the co-treatment: the MAPK and ErbB pathways. We validated the only miRNA upregulated specifically by the co-treatment associated with the MAPK signaling, miR-331-3p. Looking for miR-331-3p targets, MAP2K7, an essential component of the JNK/MAPK pathway, was identified. Interestingly, MAP2K7 expression was downregulated during the co-treatment, causing a decrease in terms of JNK activity. miR-331-3p in mimic-transfected cells led to a significant decrease in MAP2K7 levels and promoted the reversion of GC resistance in vitro. Interestingly, miR-331-3p expression was also associated with GC-resistance in patient leukemia cells taken at diagnosis. The combination of rapamycin with MP restores GC effectiveness through the regulation of different miRNAs, suggesting the important role of these pharmacoepigenetic factors in GC response.
Assuntos
Biomarcadores Tumorais/metabolismo , Resistencia a Medicamentos Antineoplásicos , Regulação Neoplásica da Expressão Gênica , Glucocorticoides/farmacologia , MicroRNAs/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Sirolimo/farmacologia , Antibióticos Antineoplásicos/farmacologia , Apoptose , Biomarcadores Tumorais/genética , Proliferação de Células , Humanos , Proteínas Quinases Ativadas por Mitógeno/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Prognóstico , Células Tumorais CultivadasRESUMO
TP53 missense mutations leading to the expression of mutant p53 oncoproteins are frequent driver events during tumorigenesis. p53 mutants promote tumor growth, metastasis and chemoresistance by affecting fundamental cellular pathways and functions. Here, we demonstrate that p53 mutants modify structure and function of the Golgi apparatus, culminating in the increased release of a pro-malignant secretome by tumor cells and primary fibroblasts from patients with Li-Fraumeni cancer predisposition syndrome. Mechanistically, interacting with the hypoxia responsive factor HIF1α, mutant p53 induces the expression of miR-30d, which in turn causes tubulo-vesiculation of the Golgi apparatus, leading to enhanced vesicular trafficking and secretion. The mut-p53/HIF1α/miR-30d axis potentiates the release of soluble factors and the deposition and remodeling of the ECM, affecting mechano-signaling and stromal cells activation within the tumor microenvironment, thereby enhancing tumor growth and metastatic colonization.
Assuntos
Neoplasias da Mama/genética , Transformação Celular Neoplásica/genética , Complexo de Golgi/patologia , Síndrome de Li-Fraumeni/genética , MicroRNAs/metabolismo , Proteína Supressora de Tumor p53/genética , Animais , Biópsia , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Transformação Celular Neoplásica/metabolismo , Feminino , Fibroblastos , Regulação Neoplásica da Expressão Gênica , Complexo de Golgi/metabolismo , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Síndrome de Li-Fraumeni/patologia , Camundongos , Microtúbulos/metabolismo , Microtúbulos/patologia , Mutação , Cultura Primária de Células , Vesículas Secretórias/metabolismo , Vesículas Secretórias/patologia , Transdução de Sinais/genética , Pele/citologia , Pele/patologia , Microambiente Tumoral/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Missense mutations in the TP53 gene are frequent in human cancers, giving rise to mutant p53 proteins that can acquire oncogenic properties. Gain of function mutant p53 proteins can enhance tumour aggressiveness by promoting cell invasion, metastasis and chemoresistance. Accumulating evidences indicate that mutant p53 proteins can also modulate cell homeostatic processes, suggesting that missense p53 mutation may increase resistance of tumour cells to intrinsic and extrinsic cancer-related stress conditions, thus offering a selective advantage. Here we provide evidence that mutant p53 proteins can modulate the Unfolded Protein Response (UPR) to increase cell survival upon Endoplasmic Reticulum (ER) stress, a condition to which cancer cells are exposed during tumour formation and progression, as well as during therapy. Mechanistically, this action of mutant p53 is due to enhanced activation of the pro-survival UPR effector ATF6, coordinated with inhibition of the pro-apoptotic UPR effectors JNK and CHOP. In a triple-negative breast cancer cell model with missense TP53 mutation, we found that ATF6 activity is necessary for viability and invasion phenotypes. Together, these findings suggest that ATF6 inhibitors might be combined with mutant p53-targeting drugs to specifically sensitise cancer cells to endogenous or chemotherapy-induced ER stress.
Assuntos
Fator 6 Ativador da Transcrição/genética , Estresse do Retículo Endoplasmático/genética , Neoplasias/genética , Proteína Supressora de Tumor p53/genética , Resposta a Proteínas não Dobradas/genética , Fator 6 Ativador da Transcrição/metabolismo , Animais , Células Cultivadas , Progressão da Doença , Retículo Endoplasmático/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Células MCF-7 , Camundongos , Camundongos Transgênicos , Mutação/fisiologia , Invasividade Neoplásica , Neoplasias/metabolismo , Neoplasias/patologia , Regulação para CimaRESUMO
Forty years of research have established that the p53 tumor suppressor provides a major barrier to neoplastic transformation and tumor progression by its unique ability to act as an extremely sensitive collector of stress inputs, and to coordinate a complex framework of diverse effector pathways and processes that protect cellular homeostasis and genome stability. Missense mutations in the TP53 gene are extremely widespread in human cancers and give rise to mutant p53 proteins that lose tumor suppressive activities, and some of which exert trans-dominant repression over the wild-type counterpart. Cancer cells acquire selective advantages by retaining mutant forms of the protein, which radically subvert the nature of the p53 pathway by promoting invasion, metastasis and chemoresistance. In this review, we consider available evidence suggesting that mutant p53 proteins can favor cancer cell survival and tumor progression by acting as homeostatic factors that sense and protect cancer cells from transformation-related stress stimuli, including DNA lesions, oxidative and proteotoxic stress, metabolic inbalance, interaction with the tumor microenvironment, and the immune system. These activities of mutant p53 may explain cancer cell addiction to this particular oncogene, and their study may disclose tumor vulnerabilities and synthetic lethalities that could be exploited for hitting tumors bearing missense TP53 mutations.
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Transformação Celular Neoplásica/genética , Proteínas Mutantes/metabolismo , Neoplasias/metabolismo , Oncogenes , Proteína Supressora de Tumor p53/genética , Regulação Neoplásica da Expressão Gênica , Humanos , Terapia de Alvo Molecular , Mutação de Sentido Incorreto , Neoplasias/tratamento farmacológico , Neoplasias/genética , Microambiente Tumoral/genéticaRESUMO
Breast cancer is the most frequently diagnosed malignancy in women, and mutations in the tumor suppressor p53 are commonly detected in the most aggressive subtypes. The majority of TP53 gene alterations are missense substitutions, leading to expression of mutant forms of the p53 protein that are frequently detected at high levels in cancer cells. P53 mutants not only lose the physiological tumor-suppressive activity of the wild-type p53 protein but also acquire novel powerful oncogenic functions, referred to as gain of function, that may actively confer a selective advantage during tumor progression. Some of the best-characterized oncogenic activities of mutant p53 are mediated by its ability to form aberrant protein complexes with other transcription factors or proteins not directly related to gene transcription. The set of cellular proteins available to interact with mutant p53 is dependent on cell type and extensively affected by environmental signals, so the prognostic impact of p53 mutation is complex. Specific functional interactions of mutant p53 can profoundly impact homeostasis of breast cancer cells, reprogramming gene expression in response to specific extracellular inputs or cell-intrinsic conditions. The list of protein complexes involving mutant p53 in breast cancer is continuously growing, as is the number of oncogenic phenotypes in which they could be involved. In consideration of the functional impact of such complexes, key interactions of mutant p53 may be exploited as potential targets for development of therapies aimed at defusing the oncogenic potential of p53 mutation.
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The tumor suppressor DAB2IP contributes to modulate the network of information established between cancer cells and tumor microenvironment. Epigenetic and post-transcriptional inactivation of this protein is commonly observed in multiple human malignancies, and can potentially favor progression of tumors driven by a variety of genetic mutations. Performing a high-throughput screening of a large collection of human microRNA mimics, we identified miR-149-3p as a negative post-transcriptional modulator of DAB2IP. By efficiently downregulating DAB2IP, this miRNA enhances cancer cell motility and invasiveness, facilitating activation of NF-kB signaling and promoting expression of pro-inflammatory and pro-angiogenic factors. In addition, we found that miR-149-3p secreted by prostate cancer cells induces DAB2IP downregulation in recipient vascular endothelial cells, stimulating their proliferation and motility, thus potentially remodeling the tumor microenvironment. Finally, we found that inhibition of endogenous miR-149-3p restores DAB2IP activity and efficiently reduces tumor growth and dissemination of malignant cells. These observations suggest that miR-149-3p can promote cancer progression via coordinated inhibition of DAB2IP in tumor cells and in stromal cells.
Assuntos
MicroRNAs/metabolismo , Proteínas de Neoplasias/metabolismo , Neoplasias da Próstata/metabolismo , RNA Neoplásico/metabolismo , Transdução de Sinais , Microambiente Tumoral , Proteínas Ativadoras de ras GTPase/metabolismo , Animais , Células HCT116 , Células HeLa , Células Hep G2 , Células Endoteliais da Veia Umbilical Humana , Humanos , Masculino , MicroRNAs/genética , Proteínas de Neoplasias/genética , Células PC-3 , Neoplasias da Próstata/genética , Neoplasias da Próstata/patologia , RNA Neoplásico/genética , Peixe-Zebra , Proteínas Ativadoras de ras GTPase/genéticaRESUMO
Obesity and type 2 diabetes are significant risk factors for malignancies, being associated with chronic inflammation and hyperinsulinemia. In this context, insulin can synergize with inflammation to promote proliferation, survival, and dissemination of cancer cells. Point mutation of p53 is a frequent event and a significant factor in cancer development and progression. Mutant p53 protein(s) (mutp53) can acquire oncogenic properties that increase metastasis, proliferation, and cell survival. We report that breast and prostate cancer cells with mutant p53 respond to insulin stimulation by increasing cell proliferation and invasivity, and that such a response depends on the presence of mutp53. Mechanistically, we find that mutp53 augments insulin-induced AKT1 activation by binding and inhibiting the tumor suppressor DAB2IP (DAB2-interacting protein) in the cytoplasm. This molecular axis reveals a specific gain of function for mutant p53 in the response to insulin stimulation, offering an additional perspective to understand the relationship between hyperinsulinemia and cancer evolution.
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Insulina/metabolismo , Mutação , Proteínas Proto-Oncogênicas c-akt/genética , Proteína Supressora de Tumor p53/genética , Proteínas Ativadoras de ras GTPase/metabolismo , Animais , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular , Complicações do Diabetes/tratamento farmacológico , Diabetes Mellitus/tratamento farmacológico , Progressão da Doença , Feminino , Humanos , Hiperinsulinismo/metabolismo , Inflamação , Masculino , Camundongos , Proteínas Mutantes/genética , Obesidade/complicações , Obesidade/tratamento farmacológico , Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Fatores de Risco , Proteínas Ativadoras de ras GTPase/antagonistas & inibidoresRESUMO
One of the most defining features of cancer is aberrant cell communication; therefore, a molecular understanding of the intricate network established among tumor cells and their microenvironment could significantly improve comprehension and clinical management of cancer. The tumor suppressor DAB2IP (Disabled homolog 2 interacting protein), also known as AIP1 (ASK1 interacting protein), has an important role in this context, as it modulates signal transduction by multiple inflammatory cytokines and growth factors. DAB2IP is a Ras-GAP, and negatively controls Ras-dependent mitogenic signals. In addition, acting as a signaling adaptor, DAB2IP modulates other key oncogenic pathways, including TNFα/NF-κB, WNT/ß-catenin, PI3K/AKT, and androgen receptors. Therefore, DAB2IP inactivation can provide a selective advantage to tumors initiated by a variety of driver mutations. In line with this role, DAB2IP expression is frequently impaired by methylation in cancer. Interestingly, recent studies reveal that tumor cells can employ other sophisticated mechanisms to disable DAB2IP at the post-transcriptional level. We review the mechanisms and consequences of DAB2IP inactivation in cancer, with the purpose to support and improve research aimed to counteract such mechanisms. We suggest that DAB2IP reactivation in cancer cells could be a strategy to coordinately dampen multiple oncogenic pathways, potentially limiting progression of a wide spectrum of tumors.
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Neoplasias/patologia , Proteínas Ativadoras de ras GTPase/metabolismo , Animais , Resistencia a Medicamentos Antineoplásicos , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , MAP Quinase Quinase Quinase 5/metabolismo , Neoplasias/metabolismo , Células-Tronco Neoplásicas/metabolismo , Transdução de Sinais , Ubiquitina/metabolismo , Proteínas Ativadoras de ras GTPase/química , Proteínas Ativadoras de ras GTPase/genéticaRESUMO
Inflammation and mutation of the tumor suppressor p53 are two apparently unrelated conditions that are strongly associated with cancer initiation and progression. We recently reported that gain-of-function mutant p53 modifies the response of cancer cells to inflammatory signals by binding a cytoplasmic tumor suppressor protein involved in TNFα signaling.
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Inflammation is a significant factor in cancer development, and a molecular understanding of the parameters dictating the impact of inflammation on cancers could significantly improve treatment. The tumor suppressor p53 is frequently mutated in cancer, and p53 missense mutants (mutp53) can acquire oncogenic properties. We report that cancer cells with mutp53 respond to inflammatory cytokines increasing their invasive behavior. Notably, this action is coupled to expression of chemokines that can expose the tumor to host immunity, potentially affecting response to therapy. Mechanistically, mutp53 fuels NF-κB activation while it dampens activation of ASK1/JNK by TNFα, and this action depends on mutp53 binding and inhibiting the tumor suppressor DAB2IP in the cytoplasm. Interfering with such interaction reduced aggressiveness of cancer cells in xenografts. This interaction is an unexplored mechanism by which mutant p53 can influence tumor evolution, with implications for our understanding of the complex role of inflammation in cancer.
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Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Transdução de Sinais , Fator de Necrose Tumoral alfa/metabolismo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Proteínas Ativadoras de ras GTPase/metabolismo , Animais , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Citoplasma/metabolismo , Feminino , Células HCT116 , Humanos , Metástase Linfática , Neoplasias Mamárias Experimentais , Camundongos , Camundongos SCID , Mutação de Sentido IncorretoRESUMO
It is estimated that the human mitochondrial proteome consists of 1000-1500 distinct proteins. The majority of these support the various biochemical pathways that are active in these organelles. Individuals with an oxidative phosphorylation disorder of unknown cause provide a unique opportunity to identify novel genes implicated in mitochondrial biology. We identified a homozygous deletion of CEP89 in a patient with isolated complex IV deficiency, intellectual disability and multisystemic problems. CEP89 is a ubiquitously expressed and highly conserved gene of unknown function. Immunocytochemistry and cellular fractionation experiments showed that CEP89 is present both in the cytosol and in the mitochondrial intermembrane space. Furthermore, we ascertained in vitro that downregulation of CEP89 resulted in a severe decrease in complex IV in-gel activity and altered mobility, suggesting that the complex is aberrantly formed. Two-dimensional BN-SDS gel analysis revealed that CEP89 associates with a high-molecular weight complex. Together, these data confirm a role for CEP89 in mitochondrial metabolism. In addition, we modeled CEP89 loss of function in Drosophila. Ubiquitous knockdown of fly Cep89 decreased complex IV activity and resulted in complete lethality. Furthermore, Cep89 is required for mitochondrial integrity, membrane depolarization and synaptic transmission of photoreceptor neurons, and for (sub)synaptic organization of the larval neuromuscular junction. Finally, we tested neuronal Cep89 knockdown flies in the light-off jump reflex habituation assay, which revealed its role in learning. We conclude that CEP89 proteins play an important role in mitochondrial metabolism, especially complex IV activity, and are required for neuronal and cognitive function across evolution.
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Proteínas de Ciclo Celular/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila/metabolismo , Mitocôndrias/metabolismo , Neurônios/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Criança , Cromossomos Humanos Par 19 , Deficiência de Citocromo-c Oxidase/genética , Deficiência de Citocromo-c Oxidase/metabolismo , Citosol , Modelos Animais de Doenças , Drosophila/genética , Proteínas de Drosophila/genética , Feminino , Deleção de Genes , Expressão Gênica , Técnicas de Silenciamento de Genes , Homozigoto , Humanos , Aprendizagem , Proteínas Associadas aos Microtúbulos , Mitocôndrias/genética , Mutação , Especificidade de Órgãos/genética , Polimorfismo de Nucleotídeo Único , Transporte Proteico , Sinapses/genética , Sinapses/metabolismoRESUMO
Most of the mammalian genome is transcribed. This generates a vast repertoire of transcripts that includes protein-coding messenger RNAs, long non-coding RNAs (lncRNAs) and repetitive sequences, such as SINEs (short interspersed nuclear elements). A large percentage of ncRNAs are nuclear-enriched with unknown function. Antisense lncRNAs may form sense-antisense pairs by pairing with a protein-coding gene on the opposite strand to regulate epigenetic silencing, transcription and mRNA stability. Here we identify a nuclear-enriched lncRNA antisense to mouse ubiquitin carboxy-terminal hydrolase L1 (Uchl1), a gene involved in brain function and neurodegenerative diseases. Antisense Uchl1 increases UCHL1 protein synthesis at a post-transcriptional level, hereby identifying a new functional class of lncRNAs. Antisense Uchl1 activity depends on the presence of a 5' overlapping sequence and an embedded inverted SINEB2 element. These features are shared by other natural antisense transcripts and can confer regulatory activity to an artificial antisense to green fluorescent protein. Antisense Uchl1 function is under the control of stress signalling pathways, as mTORC1 inhibition by rapamycin causes an increase in UCHL1 protein that is associated to the shuttling of antisense Uchl1 RNA from the nucleus to the cytoplasm. Antisense Uchl1 RNA is then required for the association of the overlapping sense protein-coding mRNA to active polysomes for translation. These data reveal another layer of gene expression control at the post-transcriptional level.