RESUMO
WTX encodes a tumor suppressor, frequently inactivated in Wilms tumor, with both plasma membrane and nuclear localization. WTX has been implicated in ß-catenin turnover, but its effect on nuclear proteins is unknown. We report an interaction between WTX and p53, derived from the unexpected observation of WTX, p53, and E1B 55K colocalization within the characteristic cytoplasmic body of adenovirus-transformed kidney cells. In other cells without adenovirus expression, the C-terminal domain of WTX binds to the DNA-binding domain of p53, enhances its binding to CBP, and increases CBP/p300-mediated acetylation of p53 at Lys 373/382. WTX knockdown accelerates CBP/p300 protein turnover and attenuates this modification of p53. In p53-reconstitution experiments, cell-cycle arrest, apoptosis, and p53 target-gene expression are suppressed by depletion of WTX. Together, these results suggest that WTX modulates p53 function, in part through regulation of its activator CBP/p300.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/fisiologia , Proteína Supressora de Tumor p53/metabolismo , Proteínas Supressoras de Tumor/fisiologia , Fatores de Transcrição de p300-CBP/metabolismo , Acetilação , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Células HEK293 , Humanos , Estabilidade Proteica , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismoRESUMO
WTX encodes a tumor suppressor gene inactivated in Wilms tumor and recently implicated in WNT signaling through enhancement of cytoplasmic beta-catenin (CTNNB1) degradation. Here, we report that WTX translocates to the nucleus, a property that is modified by an endogenous splicing variant and is modulated by a nuclear export inhibitor. WTX is present in distinct subnuclear structures and co-localizes with the paraspeckle marker p54NRB/NONO, suggesting a role in transcriptional regulation. Notably, WTX binds WT1, another Wilms tumor suppressor and stem cell marker that encodes a zinc-finger transcription factor, and enhances WT1-mediated transcription of Amphiregulin, an endogenous target gene. Together, these observations suggest a role for WTX in nuclear pathways implicated in the transcriptional regulation of cellular differentiation programs.
Assuntos
Transporte Ativo do Núcleo Celular , Proteínas Supressoras de Tumor/metabolismo , Proteínas WT1/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Anfirregulina , Linhagem Celular , Família de Proteínas EGF , Regulação da Expressão Gênica , Glicoproteínas/genética , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/genética , Ligação Proteica , Isoformas de Proteínas , Fatores de Transcrição , Transcrição Gênica , Transfecção , Proteínas Supressoras de Tumor/genética , Proteínas WT1/análiseRESUMO
Satellite repeats in heterochromatin are transcribed into noncoding RNAs that have been linked to gene silencing and maintenance of chromosomal integrity. Using digital gene expression analysis, we showed that these transcripts are greatly overexpressed in mouse and human epithelial cancers. In 8 of 10 mouse pancreatic ductal adenocarcinomas (PDACs), pericentromeric satellites accounted for a mean 12% (range 1 to 50%) of all cellular transcripts, a mean 40-fold increase over that in normal tissue. In 15 of 15 human PDACs, alpha satellite transcripts were most abundant and HSATII transcripts were highly specific for cancer. Similar patterns were observed in cancers of the lung, kidney, ovary, colon, and prostate. Derepression of satellite transcripts correlated with overexpression of the long interspersed nuclear element 1 (LINE-1) retrotransposon and with aberrant expression of neuroendocrine-associated genes proximal to LINE-1 insertions. The overexpression of satellite transcripts in cancer may reflect global alterations in heterochromatin silencing and could potentially be useful as a biomarker for cancer detection.
Assuntos
DNA Satélite/genética , Neoplasias/genética , Neoplasias Pancreáticas/genética , RNA Neoplásico/genética , RNA não Traduzido/genética , Animais , Carcinoma in Situ/genética , Carcinoma in Situ/patologia , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/patologia , Neoplasias do Colo/genética , Neoplasias do Colo/patologia , Metilação de DNA , DNA de Neoplasias/genética , Feminino , Expressão Gênica , Perfilação da Expressão Gênica , Heterocromatina/química , Heterocromatina/genética , Humanos , Elementos Nucleotídeos Longos e Dispersos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Masculino , Camundongos , Camundongos Nus , Neoplasias/patologia , Sistemas Neurossecretores/metabolismo , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/patologia , Neoplasias Pancreáticas/patologia , Neoplasias da Próstata/genética , Neoplasias da Próstata/patologia , RNA Neoplásico/metabolismo , RNA não Traduzido/metabolismo , Transcrição GênicaRESUMO
WTX is an X-linked tumor suppressor targeted by somatic mutations in Wilms tumor, a pediatric kidney cancer, and by germline inactivation in osteopathia striata with cranial sclerosis, a bone overgrowth syndrome. Here, we show that Wtx deletion in mice causes neonatal lethality, somatic overgrowth, and malformation of multiple mesenchyme-derived tissues, including bone, fat, kidney, heart, and spleen. Inactivation of Wtx at different developmental stages and in primary mesenchymal progenitor cells (MPCs) reveals that bone mass increase and adipose tissue deficiency are due to altered lineage fate decisions coupled with delayed terminal differentiation. Specification defects in MPCs result from aberrant ß-catenin activation, whereas alternative pathways contribute to the subsequently delayed differentiation of lineage-restricted cells. Thus, Wtx is a regulator of MPC commitment and differentiation with stage-specific functions in inhibiting canonical Wnt signaling. Furthermore, the constellation of anomalies in Wtx null mice suggests that this tumor suppressor broadly regulates MPCs in multiple tissues.
Assuntos
Células-Tronco Mesenquimais/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Animais , Diferenciação Celular , Células Cultivadas , Modelos Animais de Doenças , Células-Tronco Mesenquimais/patologia , Camundongos , Camundongos Knockout , Transdução de Sinais , Proteínas Supressoras de Tumor/deficiênciaRESUMO
Cancers with specific genetic mutations are susceptible to selective kinase inhibitors. However, there is a wide spectrum of benefit among cancers harboring the same sensitizing genetic mutations. Herein, we measured apoptotic rates among cell lines sharing the same driver oncogene following treatment with the corresponding kinase inhibitor. There was a wide range of kinase inhibitor-induced apoptosis despite comparable inhibition of the target and associated downstream signaling pathways. Surprisingly, pretreatment RNA levels of the BH3-only pro-apoptotic BIM strongly predicted the capacity of EGFR, HER2, and PI3K inhibitors to induce apoptosis in EGFR-mutant, HER2-amplified, and PIK3CA-mutant cancers, respectively, but BIM levels did not predict responsiveness to standard chemotherapies. Furthermore, BIM RNA levels in EGFR-mutant lung cancer specimens predicted response and duration of clinical benefit from EGFR inhibitors. These findings suggest assessment of BIM levels in treatment-naïve tumor biopsies may indicate the degree of benefit from single-agent kinase inhibitors in multiple oncogene-addiction paradigms.
Assuntos
Proteínas Reguladoras de Apoptose/biossíntese , Proteínas Reguladoras de Apoptose/genética , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/genética , Proteínas de Membrana/biossíntese , Proteínas de Membrana/genética , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas/biossíntese , Proteínas Proto-Oncogênicas/genética , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Proteína Agonista de Morte Celular de Domínio Interatuante com BH3/genética , Proteína Agonista de Morte Celular de Domínio Interatuante com BH3/metabolismo , Proteína 11 Semelhante a Bcl-2 , Linhagem Celular Tumoral , Estudos de Coortes , Receptores ErbB/antagonistas & inibidores , Receptores ErbB/genética , Receptores ErbB/metabolismo , Feminino , Humanos , Neoplasias Pulmonares/metabolismo , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Nus , Oncogenes , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Inibidores de Fosfoinositídeo-3 Quinase , Proteínas Proto-Oncogênicas/metabolismo , Receptor ErbB-2/antagonistas & inibidores , Receptor ErbB-2/genética , Receptor ErbB-2/metabolismo , Estudos Retrospectivos , Transdução de Sinais/efeitos dos fármacosRESUMO
Wilms tumor is the most common pediatric kidney cancer. To identify transcriptional and epigenetic mechanisms that drive this disease, we compared genome-wide chromatin profiles of Wilms tumors, embryonic stem cells (ESCs), and normal kidney. Wilms tumors prominently exhibit large active chromatin domains previously observed in ESCs. In the cancer, these domains frequently correspond to genes that are critical for kidney development and expressed in the renal stem cell compartment. Wilms cells also express "embryonic" chromatin regulators and maintain stem cell-like p16 silencing. Finally, Wilms and ESCs both exhibit "bivalent" chromatin modifications at silent promoters that may be poised for activation. In Wilms tumor, bivalent promoters correlate to genes expressed in specific kidney compartments and point to a kidney-specific differentiation program arrested at an early-progenitor stage. We suggest that Wilms cells share a transcriptional and epigenetic landscape with a normal renal stem cell, which is inherently susceptible to transformation and may represent a cell of origin for this disease.