RESUMEN
Myocardin is known as an important transcriptional regulator in smooth and cardiac muscle development. Here we found that myocardin is frequently repressed during human malignant transformation, contributing to a differentiation defect. We demonstrate that myocardin is a transcriptional target of TGFbeta required for TGFbeta-mediated differentiation of human fibroblasts. Serum deprivation, intact contact inhibition response, and the p16ink4a/Rb pathway contribute to myocardin induction and differentiation. Restoration of myocardin expression in sarcoma cells results in differentiation and inhibition of malignant growth, whereas inactivation of myocardin in normal fibroblasts increases their proliferative potential. Myocardin expression is reduced in multiple types of human tumors. Collectively, our results demonstrate that myocardin is an important suppressive modifier of the malignant transformation process.
Asunto(s)
Diferenciación Celular , Transformación Celular Neoplásica , Inhibidor p16 de la Quinasa Dependiente de Ciclina/antagonistas & inhibidores , Fibroblastos/citología , Proteínas Nucleares/antagonistas & inhibidores , Transactivadores/antagonistas & inhibidores , Western Blotting , Adhesión Celular , Proliferación Celular , Células Cultivadas , Ensayo de Unidades Formadoras de Colonias , Inhibidor p16 de la Quinasa Dependiente de Ciclina/genética , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Metilación de ADN , Fibroblastos/metabolismo , Técnica del Anticuerpo Fluorescente , Regulación de la Expresión Génica , Humanos , Pulmón/embriología , Mesodermo/citología , Mesodermo/metabolismo , Neoplasias/metabolismo , Neoplasias/patología , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Plásmidos , Regiones Promotoras Genéticas , ARN Interferente Pequeño/farmacología , Transactivadores/genética , Transactivadores/metabolismo , Factor de Crecimiento Transformador beta/farmacologíaRESUMEN
Concomitant expression of mutant p53 and oncogenic Ras, leading to cellular transformation, is well documented. However, the mechanisms by which the various mutant p53 categories cooperate with Ras remain largely obscure. From this study we suggest that different mutant p53 categories cooperate with H-Ras in different ways to induce a unique expression pattern of a cancer-related gene signature (CGS). The DNA-contact p53 mutants (p53(R248Q) and p53(R273H)) exhibited the highest level of CGS expression by cooperating with NFκB. Furthermore, the Zn(+2) region conformational p53 mutants (p53(R175H) and p53(H179R)) induced the CGS by elevating H-Ras activity. This elevation in H-Ras activity stemmed from a perturbed function of the p53 transcription target gene, BTG2. By contrast, the L3 loop region conformational mutant (p53(G245S)) did not affect CGS expression. Our findings were further corroborated in human tumor-derived cell lines expressing Ras and the aforementioned mutated p53 proteins. These data might assist in future tailor-made therapy targeting the mutant p53-Ras axis in cancer.
Asunto(s)
Regulación Enzimológica de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Genes ras , Transcriptoma , Proteína p53 Supresora de Tumor/metabolismo , Línea Celular Tumoral , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/metabolismo , Quimiocina CXCL1/genética , Quimiocina CXCL1/metabolismo , Activación Enzimática , Humanos , Proteínas Inmediatas-Precoces/genética , Proteínas Inmediatas-Precoces/metabolismo , Mutación , FN-kappa B/genética , FN-kappa B/metabolismo , Mapeo de Interacción de Proteínas , Transcripción Genética , Transfección , Proteína p53 Supresora de Tumor/genética , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismo , Zinc/metabolismoRESUMEN
Uncontrolled accumulation of reactive oxygen species (ROS) causes oxidative stress and induces harmful effects. Both high ROS levels and p53 mutations are frequent in human cancer. Mutant p53 forms are known to actively promote malignant growth. However, no mechanistic details are known about the contribution of mutant p53 to excessive ROS accumulation in cancer cells. Herein, we examine the effect of p53(R273H), a commonly occurring mutated p53 form, on the expression of phase 2 ROS-detoxifying enzymes and on the ability of cells to readopt a reducing environment after exposure to oxidative stress. Our data suggest that p53(R273H) mutant interferes with the normal response of human cells to oxidative stress. We show here that, upon oxidative stress, mutant p53(R273H) attenuates the activation and function of NF-E2-related factor 2 (NRF2), a transcription factor that induces the antioxidant response. This effect of mutant p53 is manifested by decreased expression of phase 2 detoxifying enzymes NQO1 and HO-1 and high ROS levels. These findings were observed in several human cancer cell lines, highlighting the general nature of this phenomenon. The failure of p53(R273H) mutant-expressing cells to restore a reducing oxidative environment was accompanied by increased survival, a known consequence of mutant p53 expression. These activities are attributable to mutant p53(R273H) gain of function and might underlie its well-documented oncogenic nature in human cancer.
Asunto(s)
Sustitución de Aminoácidos/genética , Neoplasias del Colon/enzimología , Neoplasias del Colon/patología , Fase II de la Desintoxicación Metabólica/genética , Proteínas Mutantes/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Proteína p53 Supresora de Tumor/genética , Apoptosis/efectos de los fármacos , Apoptosis/genética , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/genética , Técnicas de Silenciamiento del Gen , Células HCT116 , Hemo-Oxigenasa 1/metabolismo , Humanos , Maleatos/farmacología , Mutación/genética , NAD(P)H Deshidrogenasa (Quinona)/metabolismo , Factor 2 Relacionado con NF-E2/metabolismo , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/genética , ARN Interferente Pequeño/metabolismo , Superóxidos/metabolismo , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
Cytochrome P450 (P450) enzymes are abundantly expressed in the human liver where they hydroxylate organic substrates. In a microarray screen performed in human liver cells, we found a group of eleven P450 genes whose expression was induced by p53 (CYP3A4, CYP3A43, CYP3A5, CYP3A7, CYP4F2, CYP4F3, CYP4F11, CYP4F12, CYP19A1, CYP21A2 and CYP24A1). The mode of regulation of four representative genes (CYP3A4, CYP3A7, CYP4F2 and CYP4F3) was further characterized. The genes were induced in a p53-dependent manner in HepG2 and Huh6 cells (both are cancer-derived human liver cells) and in primary liver cells isolated from human donors. Furthermore, p53 was found to bind to p53-responsive elements in the genes' DNA-regulatory regions and to enhance their transcription in a reporter gene assay. Importantly, when p53 was activated following the administration of either of three different anticancer chemotherapeutic agents (cisplatin, etoposide or doxorubicin), it was able to induce CYP3A genes, which are the main factors in systemic clearance of these agents. Finally, the p53-dependent induction of P450 genes following either Nutlin or chemotherapy treatment led to enhanced P450 enzymatic activity. Thus, in addition to the well-established role of p53 at the tumor site, our data unravels a novel function of hepatic p53 in inducing P450 enzymes and position p53 as a major factor in the hepatic response to xenobiotic and metabolic signals. Importantly, this study reveals a novel pathway for the induction of CYP3As by their substrates through p53, warranting the need for careful consideration when designing systemically administered chemotherapeutic regimens.
Asunto(s)
Antineoplásicos/farmacología , Citocromo P-450 CYP3A/metabolismo , Proteína p53 Supresora de Tumor/metabolismo , Secuencia de Bases , Línea Celular , Inmunoprecipitación de Cromatina , ADN , Humanos , Metabolismo de los Lípidos/genética , Reacción en Cadena en Tiempo Real de la PolimerasaRESUMEN
BACKGROUND & AIMS: In this study we aimed at characterizing the regulation of hepatic metabolic pathways by the p53 transcription factor. METHODS: Analysis of gene expression following alteration of p53 status in several human- and mouse-derived cells using microarray analysis, quantitative real-time PCR, chromatin immunoprecipitation, and reporter gene assays. A functional assay was performed to determine lipid transfer activity. RESULTS: We identified a novel role for the p53 protein in regulating lipid and lipoprotein metabolism, a process not yet conceived as related to p53, which is known mainly for its tumor suppressive functions. We revealed a group of 341 genes whose expression was induced by p53 in the liver-derived cell line HepG2. Twenty of these genes encode proteins involved in many aspects of lipid homeostasis. The mode of regulation of three representative genes (Pltp, Abca12, and Cel) was further characterized. In addition to HepG2, the genes were induced following activation of p53 in human primary hepatic cells isolated from liver donors. p53-dependent regulation of these genes was evident in other cell types namely Hep3B cells, mouse hepatocytes, and fibroblasts. Furthermore, p53 was found to bind to the genes' promoters in designated p53 responsive elements and thereby increase transcription. Importantly, p53 augmented the activity of secreted PLTP, which plays a major role in lipoprotein biology and atherosclerosis pathology. CONCLUSIONS: These findings expose another facet of p53 functions unrelated to tumor suppression and render it a novel regulator of hepatic lipid metabolism and consequently of systemic lipid homeostasis and atherosclerosis development.
Asunto(s)
Metabolismo de los Lípidos/fisiología , Hígado/metabolismo , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismo , Transportadoras de Casetes de Unión a ATP/genética , Transportadoras de Casetes de Unión a ATP/metabolismo , Animales , Aterosclerosis/metabolismo , Fibroblastos/citología , Fibroblastos/fisiología , Perfilación de la Expresión Génica , Células Hep G2 , Hepatocitos/citología , Hepatocitos/fisiología , Homeostasis/fisiología , Humanos , Lipasa/genética , Lipasa/metabolismo , Hígado/citología , Ratones , Análisis por Micromatrices , Proteínas de Transferencia de Fosfolípidos/genética , Proteínas de Transferencia de Fosfolípidos/metabolismoRESUMEN
Cancer is viewed as being governed by several aberrant biological events defined by Weinberg and Hanahan as 'hallmarks'. In most human cancers the tumour suppressor p53 is mutated, leading to its malfunction and to the acquirement of oncogenic activities, termed 'gain of function'. This commentary links mutant p53 activities to the hallmarks of cancer, describing its involvement in resistance to apoptosis, genomic instability, aberrant cell cycle, invasion and metastasis, tumour microenvironment, and inflammation. Recent work published in The Journal of Pathology by Acin and colleagues, summarized here, reveals an interesting mechanism by which mutant p53 accelerates mitosis entry. Collectively, the growing body of evidence relating mutant p53 and the hallmarks of cancer reinforces the notion that targeting mutant p53 pathways might be beneficial for anti-cancer therapy.
Asunto(s)
Carcinoma de Células Escamosas/genética , Eliminación de Gen , Regulación Neoplásica de la Expresión Génica , Genes p53/genética , Genes ras/genética , Neoplasias de Cabeza y Cuello/genética , Mutación , AnimalesRESUMEN
Compelling evidences have rendered the tumor microenvironment a crucial determinant in cancer outcome. Activating transcription factor 3 (ATF3), a stress response transcription factor, is known to have a dichotomous role in tumor cells, acting either as a tumor suppressor or an oncogene in a context-dependent manner. However, its expression and possible role in the tumor microenvironment are hitherto unknown. Here we show that ATF3 is upregulated in the stromal compartment of several types of cancer. Accordingly, Cancer-associated fibroblasts (CAFs) ectopically expressing ATF3 proliferated faster as indicated by increased colony-forming capacity and promoted the growth of adjacent tumor cells when co-injected into nude mice. Utilizing a genome-wide profiling approach, we unraveled a robust gene expression program induced by ATF3 in CAFs. Focusing on a specific subset of genes, we found that the ability of stromal ATF3 to promote cancer progression is mediated by transcriptional repression of CLDN1 and induction of CXCL12 and RGS4. In addition, regulation of LIF, CLDN1, SERPINE2, HSD17B2, ITGA7 and PODXL by ATF3 mediated the increased proliferation capacity of CAFs. In sum, our findings implicate ATF3 as a novel stromal tumor promoter and suggest that targeting ATF3 pathway might be beneficial for anticancer therapy.
Asunto(s)
Factor de Transcripción Activador 3/fisiología , Neoplasias/genética , Transcripción Genética/fisiología , Western Blotting , Compartimento Celular , Línea Celular Tumoral , Proliferación Celular , Progresión de la Enfermedad , Regulación Neoplásica de la Expresión Génica , Humanos , Neoplasias/metabolismo , Neoplasias/patología , Reacción en Cadena en Tiempo Real de la Polimerasa , Células del Estroma/metabolismoRESUMEN
Fibroblasts located adjacent to the tumor [cancer-associated fibroblasts (CAFs)] that constitute a large proportion of the cancer-associated stroma facilitate the transformation process. In this study, we compared the biological behavior of CAFs that were isolated from a prostate tumor to their normal-associated fibroblast (NAF) counterparts. CAFs formed more colonies when seeded at low cell density, exhibited a higher proliferation rate and were less prone to contact inhibition. In contrast to the general notion that high levels of alpha-smooth muscle actin serve as a marker for CAFs, we found that prostate CAFs express it at a lower level compared with prostate NAFs. Microarray analysis revealed a set of 161 genes that were altered in CAFs compared with NAFs. We focused on whey acidic protein four-disulfide core domain 1 (WFDC1), a known secreted protease inhibitor, and found it to be downregulated in the CAFs. WFDC1 expression was also dramatically downregulated in highly prolific mesenchymal cells and in various cancers including fibrosarcomas and in tumors of the lung, bladder and brain. Overexpression of WFDC1 inhibited the growth rate of the fibrosarcoma HT1080 cell line. Furthermore, WFDC1 level was upregulated in senescent fibroblasts. Taken together, our data suggest an important role for WFDC1 in inhibiting proliferation of both tumors and senescent cells. Finally, we suggest that the downregulation of WFDC1 might serve as a biomarker for cellular transformation.
Asunto(s)
Transformación Celular Neoplásica/genética , Senescencia Celular/genética , Proteínas/genética , Secuencia de Bases , Células Cultivadas , Cartilla de ADN , Perfilación de la Expresión Génica , Humanos , Cariotipificación , Análisis de Secuencia por Matrices de Oligonucleótidos , Reacción en Cadena de la Polimerasa , Regulación hacia ArribaRESUMEN
It is well accepted that tumor microenvironment is essential for tumor cells survival, cancer progression and metastasis. However, the mechanisms by which tumor cells interact with their surrounding at early stages of cancer development are largely unidentified. The aim of this study was to identify specific molecules involved in stromal-epithelial interactions that might contribute to early stages of prostate tumor formation. Here, we show that conditioned medium (CM) from immortalized non-transformed prostate epithelial cells stimulated immortalized prostate stromal cells to express cancer-related molecules. CM obtained from epithelial cells triggered stromal cells to express and secrete CXCL-1, CXCL-2, CXCL-3 and interleukin (IL)-8 chemokines. This effect was predominantly mediated by the cytokines of the IL-1 family secreted by the epithelial cells. Thus, prostate epithelial cells induced the secretion of proinflammatory and cancer-promoting chemokines by prostate stromal cells. Such interactions might contribute to prostatic inflammation and progression at early stages of prostate cancer formation.
Asunto(s)
Quimiocina CXCL1/metabolismo , Quimiocina CXCL2/metabolismo , Quimiocinas CXC/metabolismo , Interleucina-1/farmacología , Interleucina-8/metabolismo , Próstata/metabolismo , Western Blotting , Comunicación Celular , Proliferación Celular , Células Cultivadas , Quimiocina CXCL1/genética , Quimiocina CXCL2/genética , Quimiocinas CXC/genética , Medios de Cultivo Condicionados/farmacología , Ensayo de Inmunoadsorción Enzimática , Células Epiteliales/metabolismo , Humanos , Interleucina-8/genética , Masculino , Próstata/patología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Células del Estroma/metabolismoRESUMEN
Normal cell growth is governed by a complicated biological system, featuring multiple levels of control, often deregulated in cancers. The role of microRNAs (miRNAs) in the control of gene expression is now increasingly appreciated, yet their involvement in controlling cell proliferation is still not well understood. Here we investigated the mammalian cell proliferation control network consisting of transcriptional regulators, E2F and p53, their targets and a family of 15 miRNAs. Indicative of their significance, expression of these miRNAs is downregulated in senescent cells and in breast cancers harboring wild-type p53. These miRNAs are repressed by p53 in an E2F1-mediated manner. Furthermore, we show that these miRNAs silence antiproliferative genes, which themselves are E2F1 targets. Thus, miRNAs and transcriptional regulators appear to cooperate in the framework of a multi-gene transcriptional and post-transcriptional feed-forward loop. Finally, we show that, similarly to p53 inactivation, overexpression of representative miRNAs promotes proliferation and delays senescence, manifesting the detrimental phenotypic consequence of perturbations in this circuit. Taken together, these findings position miRNAs as novel key players in the mammalian cellular proliferation network.
Asunto(s)
Proliferación Celular , Factores de Transcripción E2F/fisiología , Redes Reguladoras de Genes/fisiología , MicroARNs/fisiología , Proteína p53 Supresora de Tumor/fisiología , Animales , Neoplasias de la Mama , Senescencia Celular , Factor de Transcripción E2F1 , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Masculino , Biología de SistemasRESUMEN
Cancer associated fibroblasts (CAFs) are a subpopulation of cells that reside within the tumor microenvironment and promotes the transformation process by encouraging tumor growth, angiogenesis, inflammation, and metastasis. CAF-specific proteins serve as both prognostic markers and targets for anticancer drugs. With the growing interest in CAFs, several controversial issues have been raised, including the genomic landscape of these cells, the identity of specific markers, and their cell of origin. Here, we tackle these debated issues and put forward a new definition for 'CAF' as a cell 'state' rather than a cell type. We hope this conceptualization can resolve the ongoing discrepancies revolving around CAF research and aid in designing better anti-cancer treatment strategies.
Asunto(s)
Fibroblastos/metabolismo , Neoplasias/metabolismo , Microambiente Tumoral , Animales , Biomarcadores de Tumor , Humanos , Neoplasias/genética , Neoplasias/fisiopatología , Células del Estroma/metabolismoRESUMEN
BACKGROUND: The p53 tumor suppressor protein is a transcription factor that initiates transcriptional programs aimed at inhibiting carcinogenesis. p53 represses metabolic pathways that support tumor development (such as glycolysis and the pentose phosphate pathway (PPP)) and enhances metabolic pathways that are considered counter-tumorigenic such as fatty acid oxidation. FINDINGS: In an attempt to comprehensively define metabolic pathways regulated by p53, we performed two consecutive high-throughput analyses in human liver-derived cells with varying p53 statuses. A gene expression microarray screen followed by constraint-based modeling (CBM) predicting metabolic changes imposed by the transcriptomic changes suggested a role for p53 in enhancing gluconeogenesis (de novo synthesis of glucose). Examining glucogenic gene expression revealed a p53-dependent induction of genes involved in both gluconeogenesis (G6PC, PCK2) and in supplying glucogenic precursors (glycerol kinase (GK), aquaporin 3 (AQP3), aquaporin 9 (AQP9) and glutamic-oxaloacetic transaminase 1 (GOT1)). Accordingly, p53 augmented hepatic glucose production (HGP) in both human liver cells and primary mouse hepatocytes. CONCLUSIONS: These findings portray p53 as a novel regulator of glucose production. By facilitating glucose export, p53 may prevent it from being shunted to pro-cancerous pathways such as glycolysis and the PPP. Thus, our findings suggest a metabolic pathway through which p53 may inhibit tumorigenesis.
RESUMEN
Mutations in the p53 tumor suppressor protein are highly frequent in tumors and often endow cells with tumorigenic capacities. We sought to examine a possible role for mutant p53 in the cross-talk between cancer cells and their surrounding stroma, which is a crucial factor affecting tumor outcome. Here we present a novel model which enables individual monitoring of the response of cancer cells and stromal cells (fibroblasts) to co-culturing. We found that fibroblasts elicit the interferon beta (IFNß) pathway when in contact with cancer cells, thereby inhibiting their migration. Mutant p53 in the tumor was able to alleviate this response via SOCS1 mediated inhibition of STAT1 phosphorylation. IFNß on the other hand, reduced mutant p53 RNA levels by restricting its RNA stabilizer, WIG1. These data underscore mutant p53 oncogenic properties in the context of the tumor microenvironment and suggest that mutant p53 positive cancer patients might benefit from IFNß treatment.
Asunto(s)
Fibroblastos/metabolismo , Interferón beta/metabolismo , Microambiente Tumoral , Proteína p53 Supresora de Tumor/genética , Proteínas Portadoras/metabolismo , Línea Celular Tumoral , Movimiento Celular , Técnicas de Cocultivo , Humanos , Neoplasias Pulmonares , Mutación , Proteínas Nucleares/metabolismo , Fosforilación , Procesamiento Proteico-Postraduccional , Estabilidad del ARN , Proteínas de Unión al ARN , Factor de Transcripción STAT1/metabolismo , Proteína 1 Supresora de la Señalización de Citocinas , Proteínas Supresoras de la Señalización de Citocinas/metabolismo , Escape del Tumor , Proteína p53 Supresora de Tumor/metabolismo , Regulación hacia ArribaRESUMEN
The theoretical framework for the field of cancer research is based on two main principles. The first is that cancer advances in a stepwise manner, with each alteration driving cells further toward a malignant state. Second, to cure cancer we must target only cancer-specific properties. Here, we analyze the birth and propagation of the cancer research paradigm. We believe the current paradigm is immersed in crisis and that the field would benefit from integrating theories within and outside the normal modes of research to compile a new framework, with the hope of faster progress and significantly fewer cancer-related deaths.
Asunto(s)
Neoplasias , Investigación/tendencias , Humanos , Neoplasias/etiología , Neoplasias/prevención & control , Neoplasias/terapiaRESUMEN
Mesenchymal stromal cells (MSC) are used extensively in clinical trials; however, the possibility that MSCs have a potential for malignant transformation was raised. We examined the genomic stability versus the tumor-forming capacity of multiple mouse MSCs. Murine MSCs have been shown to be less stable and more prone to malignant transformation than their human counterparts. A large series of independently isolated MSC populations exhibited low tumorigenic potential under syngeneic conditions, which increased in immunocompromised animals. Unexpectedly, higher ploidy correlated with reduced tumor-forming capacity. Furthermore, in both cultured MSCs and primary hepatocytes, polyploidization was associated with a dramatic decrease in the expression of the long noncoding RNA H19. Direct knockdown of H19 expression in diploid cells resulted in acquisition of polyploid cell traits. Moreover, artificial tetraploidization of diploid cancer cells led to a reduction of H19 levels, as well as to an attenuation of the tumorigenic potential. Polyploidy might therefore serve as a protective mechanism aimed at reducing malignant transformation through the involvement of the H19 regulatory long noncoding RNA.
Asunto(s)
Transformación Celular Neoplásica/genética , Silenciador del Gen/fisiología , Células Madre Mesenquimatosas/metabolismo , Células Madre Mesenquimatosas/patología , Poliploidía , ARN Largo no Codificante/genética , Animales , Transformación Celular Neoplásica/patología , Células Cultivadas , Inestabilidad Genómica , Células Madre Mesenquimatosas/fisiología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Endogámicos NOD , Ratones Noqueados , Ratones SCID , Neoplasias/genética , ARN Largo no Codificante/antagonistas & inhibidoresRESUMEN
The transcription factor p53 functions not only to suppress tumorigenesis but also to maintain normal development and homeostasis. Although p53 was implicated in different aspects of fertility, including spermatogenesis and implantation, the mechanism underlying p53 involvement in spermatogenesis is poorly resolved. In this study we describe the identification of a spermatogenesis-associated gene, SPATA18, as a novel p53 transcriptional target and show that SPATA18 transcription is induced by p53 in a variety of cell types of both human and mouse origin. p53 binds a consensus DNA motif that resides within the first intron of SPATA18. We describe the spatiotemporal expression patterns of SPATA18 in mouse seminiferous tubules and suggest that SPATA18 transcription is regulated in vivo by p53. We also demonstrate the induction of SPATA18 by p63 and suggest that p63 can compensate for the loss of p53 activity in vivo. Our data not only enrich the known collection of p53 targets but may also provide insights on spermatogenesis defects that are associated with p53 deficiency.
Asunto(s)
Fosfoproteínas/metabolismo , Proteínas/metabolismo , Espermatogénesis , Transactivadores/metabolismo , Transcripción Genética , Proteína p53 Supresora de Tumor/metabolismo , Animales , Línea Celular , Humanos , Masculino , Ratones , Proteínas Mitocondriales , Fosfoproteínas/genética , Proteínas/genética , Interferencia de ARN , Transactivadores/genética , Proteína p53 Supresora de Tumor/deficiencia , Proteína p53 Supresora de Tumor/genéticaRESUMEN
Prostate cancer is the most common non-dermatologic malignancy in men in the Western world. Recently, a frequent chromosomal aberration fusing androgen regulated TMPRSS2 promoter and the ERG gene (TMPRSS2/ERG) was discovered in prostate cancer. Several studies demonstrated cooperation between TMPRSS2/ERG and other defective pathways in cancer progression. However, the unveiling of more specific pathways in which TMPRSS2/ERG takes part, requires further investigation. Using immortalized prostate epithelial cells we were able to show that TMPRSS2/ERG over-expressing cells undergo an Epithelial to Mesenchymal Transition (EMT), manifested by acquisition of mesenchymal morphology and markers as well as migration and invasion capabilities. These findings were corroborated in vivo, where the control cells gave rise to discrete nodules while the TMPRSS2/ERG-expressing cells formed malignant tumors, which expressed EMT markers. To further investigate the general transcription scheme induced by TMPRSS2/ERG, cells were subjected to a microarray analysis that revealed a distinct EMT expression program, including up-regulation of the EMT facilitators, ZEB1 and ZEB2, and down-regulation of the epithelial marker CDH1(E-Cadherin). A chromatin immunoprecipitation assay revealed direct binding of TMPRSS2/ERG to the promoter of ZEB1 but not ZEB2. However, TMPRSS2/ERG was able to bind the promoters of the ZEB2 modulators, IL1R2 and SPINT1. This set of experiments further illuminates the mechanism by which the TMPRSS2/ERG fusion affects prostate cancer progression and might assist in targeting TMPRSS2/ERG and its downstream targets in future drug design efforts.
Asunto(s)
Transición Epitelial-Mesenquimal , Proteínas de Homeodominio/metabolismo , Neoplasias de la Próstata/patología , Proteínas Represoras/metabolismo , Serina Endopeptidasas/metabolismo , Transactivadores/metabolismo , Factores de Transcripción/metabolismo , Animales , Línea Celular , Modelos Animales de Enfermedad , Transición Epitelial-Mesenquimal/genética , Fusión Génica , Vectores Genéticos/genética , Humanos , Masculino , Ratones , Fenotipo , Neoplasias de la Próstata/genética , Serina Endopeptidasas/genética , Transducción de Señal/genética , Transactivadores/genética , Caja Homeótica 2 de Unión a E-Box con Dedos de Zinc , Homeobox 1 de Unión a la E-Box con Dedos de ZincRESUMEN
The p53 tumor suppressor coordinates a multitude of cellular and organismal processes and exerts its activities mainly by activation of gene transcription. Here we describe the transcriptional activation of ectodysplasin A2 receptor (EDA2R) by p53 in a variety of cell types and tissues. We demonstrate that treatment of cancer cells with the ligand EDA-A2, known to specifically activate EDA2R, results in p53-dependent cell death. Moreover, we show that EDA2R is transactivated by p53 during chemotherapy-induced hair-loss, although its presence is not necessary for this process. These data shed new light on the role of EDA2R in exerting p53 function.
Asunto(s)
Alopecia/genética , Genes p53/genética , Activación Transcripcional , Proteína p53 Supresora de Tumor/fisiología , Receptor Xedar/metabolismo , Muerte Celular/genética , Regulación de la Expresión Génica , Proteína p53 Supresora de Tumor/genéticaRESUMEN
Partial gain of chromosome arm 17q is an abundant aberrancy in various cancer types such as lung and prostate cancer with a prominent occurrence and prognostic significance in neuroblastoma--one of the most common embryonic tumors. The specific genetic element/s in 17q responsible for the cancer-promoting effect of these aberrancies is yet to be defined although many genes located in 17q have been proposed to play a role in malignancy. We report here the characterization of a naturally-occurring, non-reciprocal translocation der(X)t(X;17) in human lung embryonal-derived cells following continuous culturing. This aberrancy was strongly correlated with an increased proliferative capacity and with an acquired ability to form colonies in vitro. The breakpoint region was mapped by fluorescence in situ hybridization (FISH) to the 17q24.3 locus. Further characterization by a custom-made comparative genome hybridization array (CGH) localized the breakpoint within the Bromodomain PHD finger Transcription Factor gene (BPTF), a gene involved in transcriptional regulation and chromatin remodeling. Interestingly, this translocation led to elevation in the mRNA levels of the endogenous BPTF. Knock-down of BPTF restricted proliferation suggesting a role for BPTF in promoting cellular growth. Furthermore, the BPTF chromosomal region was found to be amplified in various human tumors, especially in neuroblastomas and lung cancers in which 55% and 27% of the samples showed gain of 17q24.3, respectively. Additionally, 42% percent of the cancer cell lines comprising the NCI-60 had an abnormal BPTF locus copy number. We suggest that deregulation of BPTF resulting from the translocation may confer the cells with the observed cancer-promoting phenotype and that our cellular model can serve to establish causality between 17q aberrations and carcinogenesis.
Asunto(s)
Antígenos Nucleares/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Factores de Transcripción/metabolismo , Translocación Genética , Secuencia de Bases , Carcinógenos , Proliferación Celular , Cromosomas Humanos Par 17 , Hibridación Genómica Comparativa/métodos , Humanos , Hibridación Fluorescente in Situ , Pulmón/embriología , Neoplasias Pulmonares/genética , Modelos Genéticos , Datos de Secuencia Molecular , Neuroblastoma/metabolismo , Fenotipo , Estructura Terciaria de Proteína , TrisomíaRESUMEN
In this study, we focus on the analysis of a previously identified cancer-related gene signature (CGS) that underlies the cross talk between the p53 tumor suppressor and Ras oncogene. CGS consists of a large number of known Ras downstream target genes that were synergistically upregulated by wild-type p53 loss and oncogenic H-Ras(G12V) expression. Here we show that CGS expression strongly correlates with malignancy. In an attempt to elucidate the molecular mechanisms underling the cooperation between p53 loss and oncogenic H-Ras(G12V), we identified distinguished pathways that may account for the regulation of the expression of the CGS. By knocking-down p53 or by expressing mutant p53, we revealed that p53 exerts its negative effect by at least two mechanisms mediated by its targets B-cell translocation gene 2 (BTG2) and activating transcription factor 3 (ATF3). Whereas BTG2 binds H-Ras(G12V) and represses its activity by reducing its GTP loading state, which in turn causes a reduction in CGS expression, ATF3 binds directly to the CGS promoters following p53 stabilization and represses their expression. This study further elucidates the molecular loop between p53 and Ras in the transformation process.