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1.
Mol Cell ; 58(5): 794-803, 2015 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-25982117

RESUMO

G protein-coupled receptors (GPCRs) comprise the largest family of cell surface receptors, regulate a wide range of physiological processes, and are the major targets of pharmaceutical drugs. Canonical signaling from GPCRs is relayed to intracellular effector proteins by trimeric G proteins, composed of α, ß, and γ subunits (Gαßγ). Here, we report that G protein ß subunits (Gß) bind to DDB1 and that Gß2 targets GRK2 for ubiquitylation by the DDB1-CUL4A-ROC1 ubiquitin ligase. Activation of GPCR results in PKA-mediated phosphorylation of DDB1 at Ser645 and its dissociation from Gß2, leading to increase of GRK2 protein. Deletion of Cul4a results in cardiac hypertrophy in male mice that can be partially rescued by the deletion of one Grk2 allele. These results reveal a non-canonical function of the Gß protein as a ubiquitin ligase component and a mechanism of feedback regulation of GPCR signaling.


Assuntos
Quinase 2 de Receptor Acoplado a Proteína G/metabolismo , Subunidades beta da Proteína de Ligação ao GTP/fisiologia , Proteínas Nucleares/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitinação , Animais , Proteínas de Ligação a DNA/metabolismo , Feminino , Células HEK293 , Humanos , Masculino , Camundongos Knockout , Estabilidade Proteica , Proteólise , Ratos , Ratos Wistar , Transdução de Sinais
2.
Carcinogenesis ; 39(3): 318-326, 2018 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-29228217

RESUMO

Arf, a well-established tumor suppressor, is either mutated or downregulated in a wide array of cancers. However, its role in hepatocellular carcinoma (HCC) progression is controversial. Conflicting observations have been published regarding its expression in HCC. In this study, we provide clear genetic evidence demonstrating a protective role of p19Arf in hepatocarcinogenesis. Using Ras-induced mouse model, we show that p19Arf deficiency accelerates progression of aggressive HCC in vivo. To investigate the role of p14ARF in human liver cancers, we analyzed its expression in human HCC using immunohistochemistry (IHC). We observe lack of nucleolar p14ARF in 43.02% of human HCC samples and that low expression of p14ARF strongly correlates with the early onset of HCC. Importantly, cirrhotic livers that did not progress to HCC harbor higher expression of the p14ARF protein in hepatocytes compared with that in cirrhotic livers with HCC. These results are significant because they suggest that nucleolar p14ARF can be used as early prognostic marker in chronic liver disease to reliably identify patients with high risk for developing liver cancer. Currently, there is no effective systemic therapy for advanced liver cancer; hence, more efficient patient screening and early detection of HCC would significantly contribute to the eradication of this devastating disease.


Assuntos
Carcinoma Hepatocelular/patologia , Inibidor p16 de Quinase Dependente de Ciclina/genética , Genes ras/genética , Neoplasias Hepáticas/patologia , Proteína Supressora de Tumor p14ARF/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Carcinoma Hepatocelular/genética , Progressão da Doença , Feminino , Humanos , Cirrose Hepática/genética , Cirrose Hepática/patologia , Neoplasias Hepáticas/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pessoa de Meia-Idade
3.
J Hepatol ; 63(2): 429-36, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25828473

RESUMO

BACKGROUND & AIMS: Overexpression of FoxM1 correlates with poor prognosis in hepatocellular carcinoma (HCC). Moreover, the Ras-signaling pathway is found to be ubiquitously activated in HCC through epigenetic silencing of the Ras-regulators. We investigated the roles of FoxM1 in Ras-driven HCC, and on HCC cells with stem-like features. METHODS: We employed a transgenic mouse model that expresses the oncogenic Ras in the liver. That strain was crossed with a strain that harbor floxed alleles of FoxM1 and the MxCre gene that allows conditional deletion of FoxM1. FoxM1 alleles were deleted after development of HCC, and the effects on the tumors were analyzed. Also, FoxM1 siRNA was used in human HCC cell lines to determine its role in the survival of the HCC cells with stem cell features. RESULTS: Ras-driven tumors overexpress FoxM1. Deletion of FoxM1 inhibits HCC progression. There was increased accumulation of reactive oxygen species (ROS) in the FoxM1 deleted HCC cells. Moreover, FoxM1 deletion caused a disproportionate loss of the CD44+ and EpCAM+ HCC cells in the tumors. We show that FoxM1 directly activates expression of CD44 in human HCC cells. Moreover, the human HCC cells with stem cell features are addicted to FoxM1 for ROS-regulation and survival. CONCLUSION: Our results provide genetic evidence for an essential role of FoxM1 in the progression of Ras-driven HCC. In addition, FoxM1 is required for the expression of CD44 in HCC cells. Moreover, FoxM1 plays a critical role in the survival of the HCC cells with stem cell features by regulating ROS.


Assuntos
Carcinogênese/genética , Carcinoma Hepatocelular/genética , Fatores de Transcrição Forkhead/genética , Regulação Neoplásica da Expressão Gênica , Neoplasias Hepáticas/genética , Células-Tronco/patologia , Proteínas ras/genética , Animais , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Proliferação de Células , Progressão da Doença , Proteína Forkhead Box M1 , Fatores de Transcrição Forkhead/biossíntese , Humanos , Imuno-Histoquímica , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Prognóstico , Transdução de Sinais , Células-Tronco/metabolismo , Proteínas ras/biossíntese
4.
J Biol Chem ; 287(5): 3019-28, 2012 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-22167187

RESUMO

Exposure to ultraviolet rays (UV) in sunlight is the main cause of skin cancer. Here, we show that the p53-induced genes DDB2 and p21 are down-regulated in skin cancer, and in the mouse model they functionally cooperate to prevent UV-induced skin cancer. Our previous studies demonstrated an antagonistic role of DDB2 and p21 in nucleotide excision repair and apoptosis. Surprisingly, we find that the loss of p21 restores nucleotide excision repair and apoptosis in Ddb2(-/-) mice, but it does not protect from UV-mediated skin carcinogenesis. In contrast, Ddb2(-/-)p21(-/-) mice are significantly more susceptible to UV-induced skin cancer than the Ddb2(-/-) or the p21(-/-) mice. We provide evidence that p21 deletion in the Ddb2(-/-) background causes a strong increase in cell proliferation. The increased proliferation in the Ddb2(-/-)p21(-/-) background is related to a severe deficiency in UV-induced premature senescence. Also, the oncogenic pro-proliferation transcription factor FOXM1 is overexpressed in the p21(-/-) background. Our results show that the anti-proliferative and the pro-senescence pathways of DDB2 and p21 are critical protection mechanisms against skin malignancies.


Assuntos
Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Neoplasias Induzidas por Radiação/metabolismo , Neoplasias Cutâneas/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Raios Ultravioleta/efeitos adversos , Animais , Proliferação de Células/efeitos da radiação , Senescência Celular/genética , Senescência Celular/efeitos da radiação , Inibidor de Quinase Dependente de Ciclina p21/genética , Reparo do DNA/genética , Reparo do DNA/efeitos da radiação , Proteínas de Ligação a DNA , Proteína Forkhead Box M1 , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Deleção de Genes , Camundongos , Camundongos Knockout , Neoplasias Induzidas por Radiação/genética , Neoplasias Induzidas por Radiação/patologia , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/patologia , Proteína Supressora de Tumor p53/genética
5.
EMBO J ; 28(19): 2908-18, 2009 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-19696738

RESUMO

The transcription factor FoxM1 is over-expressed in most human malignancies. Although it is evident that FoxM1 has critical functions in tumour development and progression, the mechanisms by which FoxM1 participates in those processes are not understood. Here, we describe an essential role of FoxM1 in the regulation of oxidative stress that contributes to malignant transformation and tumour cell survival. We identify a negative feedback loop involving FoxM1 that regulates reactive oxygen species (ROS) in proliferating cells. We show that induction of FoxM1 by oncogenic Ras requires ROS. Elevated FoxM1, in turn, downregulates ROS levels by stimulating expression of ROS scavenger genes, such as MnSOD, catalase and PRDX3. FoxM1 depletion sensitizes cells to oxidative stress and increases oncogene-induced premature senescence. Moreover, tumour cells expressing activated AKT1 are 'addicted' to FoxM1, as they require continuous presence of FoxM1 for survival. Together, our results identify FoxM1 as a key regulator of ROS in dividing cells, and provide insights into the mechanism how tumour cells use FoxM1 to control oxidative stress to escape premature senescence and apoptosis.


Assuntos
Transformação Celular Neoplásica/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Estresse Oxidativo , Animais , Linhagem Celular Tumoral , Transformação Celular Neoplásica/genética , Proteína Forkhead Box M1 , Fatores de Transcrição Forkhead/genética , Regulação Neoplásica da Expressão Gênica , Genes ras , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Células NIH 3T3 , Osteossarcoma/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Espécies Reativas de Oxigênio/metabolismo
6.
J Biomed Sci ; 20: 12, 2013 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-23441825

RESUMO

BACKGROUND: Several studies have demonstrated a fundamental role for the HLA in the susceptibility of, or protection to, type 1 diabetes mellitus (T1DM). However, this has not been adequately studied in Asian Indian populations. To assess the frequency of HLA class II (DPA1, DPB1, DQA1, DQB1 and DRB1) associated to susceptibility or protection toT1DM in a Bengali population of India with diabetes. RESULTS: Single nucleotide polymorphism study. The HLA genotyping was performed by a polymerase chain reaction followed by their HLA-DP, DQ, and DRB1 genotypes and haplotypes by sequencing method. The results are studied by Plink software. The χ2 tests were used for the inferential statistics. To our knowledge, this study is the first of a kind which has attempted to check the HLA association with T1DM by SNPs analysis. The study recruited 151 patients with T1DM and same number of ethno-linguistic, sex matched non-diabetic controls. The present study found a significant SNP rs7990 of HLA-DQA1 (p = 0.009) negative correlation, again indicating that risk from HLA is considerably more with T1DM. CONCLUSIONS: This study demonstrates that the HLA class-II alleles play a major role in genetic basis of T1DM.


Assuntos
Diabetes Mellitus Tipo 1/genética , Antígenos HLA-DP/genética , Cadeias alfa de HLA-DQ/genética , Cadeias HLA-DRB1/genética , Adulto , Alelos , Diabetes Mellitus Tipo 1/patologia , Feminino , Estudos de Associação Genética , Predisposição Genética para Doença , Genótipo , Haplótipos , Humanos , Índia , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único
7.
J Pediatr Endocrinol Metab ; 36(1): 4-18, 2023 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-36424806

RESUMO

OBJECTIVES: 46, XY difference/disorder of sex development (DSD) is a relatively uncommon group of heterogeneous disorders with varying degree of underandrogenization of male genitalia. Such patients should be approached systematically to reach an aetiological diagnosis. However, we lack, at present, a clinical practice guideline on diagnostic approach in 46, XY DSD from this part of the globe. Moreover, debate persists regarding the timing and cut-offs of different hormonal tests, performed in these cases. The consensus committee consisting of 34 highly experienced endocrinologists with interest and experience in managing DSD discussed and drafted a consensus statement on the diagnostic approach to 46, XY DSD focussing on relevant history, clinical examination, biochemical evaluation, imaging and genetic analysis. CONTENT: The consensus was guided by systematic reviews of existing literature followed by discussion. An initial draft was prepared and distributed among the members. The members provided their scientific inputs, and all the relevant suggestions were incorporated. The final draft was approved by the committee members. SUMMARY: The diagnostic approach in 46, XY DSD should be multidisciplinary although coordinated by an experienced endocrinologist. We recommend formal Karyotyping, even if Y chromosome material has been detected by other methods. Meticulous history taking and thorough head-to-toe examination should initially be performed with focus on external genitalia, including location of gonads. Decision regarding hormonal and other biochemical investigations should be made according to the age and interpreted according to age-appropriate norms Although LC-MS/MS is the preferred mode of steroid hormone measurements, immunoassays, which are widely available and less expensive, are acceptable alternatives. All patients with 46, XY DSD should undergo abdominopelvic ultrasonography by a trained radiologist. MRI of the abdomen and/or laparoscopy may be used to demonstrate the Mullerian structure and/or to localize the gonads. Genetic studies, which include copy number variation (CNV) or molecular testing of a candidate gene or next generation sequencing then should be ordered in a stepwise manner depending on the clinical, biochemical, hormonal, and radiological findings. OUTLOOK: The members of the committee believe that patients with 46, XY DSD need to be approached systematically. The proposed diagnostic algorithm, provided in the consensus statement, is cost effective and when supplemented with appropriate genetic studies, may help to reach an aetiological diagnosis in majority of such cases.


Assuntos
Transtorno 46,XY do Desenvolvimento Sexual , Transtornos do Desenvolvimento Sexual , Humanos , Masculino , Transtornos do Desenvolvimento Sexual/diagnóstico , Transtornos do Desenvolvimento Sexual/genética , Cromatografia Líquida , Variações do Número de Cópias de DNA , Espectrometria de Massas em Tandem , Transtorno 46,XY do Desenvolvimento Sexual/genética
8.
Am J Respir Cell Mol Biol ; 46(4): 431-6, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22033266

RESUMO

Pulmonary arterial hypertension (PAH) is a devastating disease, and no effective treatments are available. Hypoxia-induced pulmonary artery remodeling, including smooth muscle cell proliferation, contributes to PAH, but the exact mechanisms underlying this abnormal process are largely undefined. The forkhead box M1 (FoxM1) transcription factor regulates cancer cell growth by modulating gene expression critical for cell cycle progression. Here, we report for the first time, to the best of our knowledge, a novel function of FoxM1 in the hypoxia-stimulated proliferation of human pulmonary artery smooth muscle cells (HPASMCs). Exposure to hypoxia caused a marked up-regulation of FoxM1 gene expression, mainly at the transcription level, and this induction correlated with HPASMC cell proliferation. The knockdown of FoxM1 inhibited the hypoxia-stimulated proliferation of HPASMCs. We found that the knockdown of HIF-2α, but not HIF-1α, diminished FoxM1 induction in response to hypoxia. However, the knockdown of FoxM1 did not alter expression levels of HIF-2α or HIF-1α, suggesting that HIF-2α is an upstream regulator of FoxM1. Furthermore, the knockdown of FoxM1 prevented the hypoxia-induced expression of aurora A kinase and cyclin D1. Collectively, our results suggest that hypoxia induces FoxM1 gene expression in an HIF-2α-dependent pathway, thereby promoting HPASMC proliferation.


Assuntos
Fatores de Transcrição Forkhead/metabolismo , Hipóxia/metabolismo , Miócitos de Músculo Liso/fisiologia , Artéria Pulmonar/citologia , Aurora Quinases , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Hipóxia Celular , Proliferação de Células , Células Cultivadas , Ciclina B/genética , Ciclina B/metabolismo , Ciclina D1/genética , Ciclina D1/metabolismo , Hipertensão Pulmonar Primária Familiar , Proteína Forkhead Box M1 , Fatores de Transcrição Forkhead/genética , Expressão Gênica , Humanos , Hipertensão Pulmonar/metabolismo , Hipertensão Pulmonar/patologia , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Miócitos de Músculo Liso/citologia , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Artéria Pulmonar/metabolismo
9.
Dev Biol ; 352(2): 278-87, 2011 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-21291880

RESUMO

The mammalian Cul4 genes, Cul4A and Cul4B, encode the scaffold components of the cullin-based E3 ubiquitin ligases. The two Cul4 genes are functionally redundant. Recent study indicated that mice expressing a truncated CUL4A that fails to interact with its functional partner ROC1 exhibit no developmental phenotype. We generated a Cul4A-/- strain lacking exons 4-8 that does not express any detectable truncated protein. In this strain, the male mice are infertile and exhibit severe deficiencies in spermatogenesis. The primary spermatocytes are deficient in progression through late prophase I, a time point when expression of the X-linked Cul4B gene is silenced due to meiotic sex chromosome inactivation. Testes of the Cul4A-/- mice exhibit extensive apoptosis. Interestingly, the pachytene spermatocytes exhibit persistent double stranded breaks, suggesting a deficiency in homologous recombination. Also, we find that CUL4A localizes to the double stranded breaks generated in pre-pachytene spermatocytes. The observations identify a novel function of CUL4A in meiotic recombination and demonstrate an essential role of CUL4A in spermatogenesis.


Assuntos
Proteínas Culina/fisiologia , Fertilidade/fisiologia , Espermatogênese/fisiologia , Animais , Apoptose , Sequência de Bases , Proteínas Culina/genética , Quebras de DNA de Cadeia Dupla , Primers do DNA/genética , Reparo do DNA/genética , Reparo do DNA/fisiologia , Fertilidade/genética , Masculino , Meiose/genética , Meiose/fisiologia , Prófase Meiótica I/genética , Prófase Meiótica I/fisiologia , Camundongos , Camundongos Knockout , Recombinação Genética , Espermatócitos/citologia , Espermatócitos/fisiologia , Espermatogênese/genética , Testículo/anormalidades
10.
Proc Natl Acad Sci U S A ; 106(26): 10690-5, 2009 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-19541625

RESUMO

The xeroderma pigmentosum complementation group E (XP-E) gene product damaged-DNA binding protein 2 (DDB2) plays important roles in nucleotide excision repair (NER). Previously, we showed that DDB2 participates in NER by regulating the level of p21(Waf1/Cip1). Here we show that the p21(Waf1/Cip1) -regulatory function of DDB2 plays a central role in defining the response (apoptosis or arrest) to DNA damage. The DDB2-deficient cells are resistant to apoptosis in response to a variety of DNA-damaging agents, despite activation of p53 and the pro-apoptotic genes. Instead, these cells undergo cell cycle arrest. Also, the DDB2-deficient cells are resistant to E2F1-induced apoptosis. The resistance to apoptosis of the DDB2-deficient cells is caused by an increased accumulation of p21(Waf1/Cip1) after DNA damage. We provide evidence that DDB2 targets p21(Waf1/Cip1) for proteolysis. The resistance to apoptosis in DDB2-deficient cells also involves Mdm2 in a manner that is distinct from the p53-regulatory activity of Mdm2. Our results provide evidence for a new regulatory loop involving the NER protein DDB2, Mdm2, and p21(Waf1/Cip1) that is critical in deciding cell fate (apoptosis or arrest) upon DNA damage.


Assuntos
Apoptose/fisiologia , Ciclo Celular/fisiologia , Dano ao DNA/fisiologia , Proteínas de Ligação a DNA/metabolismo , Aclarubicina/farmacologia , Animais , Antineoplásicos/farmacologia , Western Blotting , Células Cultivadas , Cisplatino/farmacologia , Inibidor de Quinase Dependente de Ciclina p21/genética , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Reparo do DNA , Proteínas de Ligação a DNA/genética , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Fibroblastos/efeitos da radiação , Citometria de Fluxo , Células HeLa , Humanos , Marcação In Situ das Extremidades Cortadas , Camundongos , Camundongos Knockout , Proteínas Proto-Oncogênicas c-mdm2/genética , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Raios Ultravioleta
11.
Int J Mol Sci ; 13(9): 11012-11026, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23109835

RESUMO

Premature senescence induced by DNA damage or oncogene is a critical mechanism of tumor suppression. Reactive oxygen species (ROS) have been implicated in the induction of premature senescence response. Several pathological disorders such as cancer, aging and age related neurological abnormalities have been linked to ROS deregulation. Here, we discuss how Damaged DNA binding Protein-2 (DDB2), a nucleotide excision repair protein, plays an important role in ROS regulation by epigenetically repressing the antioxidant genes MnSOD and Catalase. We further revisit a model in which DDB2 plays an instrumental role in DNA damage induced ROS accumulation, ROS induced premature senescence and inhibition of skin tumorigenesis.


Assuntos
Senilidade Prematura/genética , Senescência Celular/genética , Dano ao DNA/genética , Proteínas de Ligação a DNA/genética , Espécies Reativas de Oxigênio/metabolismo , Animais , Apoptose/genética , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Catalase/biossíntese , Catalase/genética , Transformação Celular Neoplásica , Proteínas Culina/metabolismo , Reparo do DNA/genética , Proteínas de Ligação a DNA/metabolismo , Humanos , Camundongos , Transdução de Sinais/genética , Neoplasias Cutâneas/patologia , Superóxido Dismutase/biossíntese , Superóxido Dismutase/genética , Xeroderma Pigmentoso/genética
12.
Oncogene ; 41(30): 3778-3790, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35761036

RESUMO

Hepatocellular carcinoma (HCC) is one of the deadliest cancers. The retinoblastoma protein (RB1), a regulator of cell proliferation, is functionally inactivated in HCC by CYCLIN D/E-mediated phosphorylation. However, the mechanism of RB1-inactivation is unclear because only small percentages of HCCs exhibit amplification of CYCLIN D/E or mutations in the CDK-inhibitory genes. We show that FOXM1, which is overexpressed and critical for HCC, plays essential roles in inactivating RB1 and suppressing RB1-induced senescence of the HCC cells. Mechanistically, FOXM1 binds RB1 and DNMT3B to repress the expression of FOXO1, leading to a decrease in the levels of the CDK-inhibitors, creating an environment for phosphorylation and inactivation of RB1. Consistent with that, inhibition of FOXM1 causes increased expression of FOXO1 with consequent activation of RB1, leading to senescence of the HCC cells, in vitro and in vivo. Also, repression-deficient mutants of FOXM1 induce senescence that is blocked by depletion of RB1 or FOXO1. We provide evidence that human HCCs rely upon this FOXM1-FOXO1 axis for phosphorylation and inactivation of RB1. The observations demonstrate the existence of a new autoregulatory loop of RB1-inactivation in HCC involving a FOXM1-FOXO1 axis that is required for phosphorylation of RB1 and for aggressive progression of HCC.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Proliferação de Células/genética , Senescência Celular , Ciclina D/metabolismo , Proteína Forkhead Box M1/genética , Proteína Forkhead Box M1/metabolismo , Proteína Forkhead Box O1/genética , Proteína Forkhead Box O1/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias Hepáticas/patologia , Proteínas de Ligação a Retinoblastoma/genética , Proteínas de Ligação a Retinoblastoma/metabolismo , Ubiquitina-Proteína Ligases/metabolismo
13.
Cancer Res ; 82(13): 2458-2471, 2022 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-35583996

RESUMO

The transcription factor Forkhead box M1 (FoxM1) is overexpressed in breast cancers and correlates with poor prognosis. Mechanistically, FoxM1 associates with CBP to activate transcription and with Rb to repress transcription. Although the activating function of FoxM1 in breast cancer has been well documented, the significance of its repressive activity is poorly understood. Using CRISPR-Cas9 engineering, we generated a mouse model that expresses FoxM1-harboring point mutations that block binding to Rb while retaining its ability to bind CBP. Unlike FoxM1-null mice, mice harboring Rb-binding mutant FoxM1 did not exhibit significant developmental defects. The mutant mouse line developed PyMT-driven mammary tumors that were deficient in lung metastasis, which was tumor cell-intrinsic. Single-cell RNA-seq of the tumors revealed a deficiency in prometastatic tumor cells and an expansion of differentiated alveolar type tumor cells, and further investigation identified that loss of the FoxM1/Rb interaction caused enhancement of the mammary alveolar differentiation program. The FoxM1 mutant tumors also showed increased Pten expression, and FoxM1/Rb was found to activate Akt signaling by repressing Pten. In human breast cancers, expression of FoxM1 negatively correlated with Pten mRNA. Furthermore, the lack of tumor-infiltrating cells in FoxM1 mutant tumors appeared related to decreases in pro-metastatic tumor cells that express factors required for infiltration. These observations demonstrate that the FoxM1/Rb-regulated transcriptome is critical for the plasticity of breast cancer cells that drive metastasis, identifying a prometastatic role of Rb when bound to FoxM1. SIGNIFICANCE: This work provides new insights into how the interaction between FoxM1 and Rb facilitates the evolution of metastatic breast cancer cells by altering the transcriptome.


Assuntos
Neoplasias da Mama , Proteína Forkhead Box M1/metabolismo , Fatores de Transcrição Forkhead , Animais , Neoplasias da Mama/patologia , Diferenciação Celular/genética , Linhagem Celular Tumoral , Feminino , Proteína Forkhead Box M1/genética , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos , Transdução de Sinais , Transcrição Gênica
14.
Hepatology ; 51(3): 922-31, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20058312

RESUMO

UNLABELLED: In this study, we determined the role of the nuclear factor-kappaB (NF-kappaB) subunit c-Rel in liver injury and regeneration. In response to toxic injury of the liver, c-Rel null (c-rel(-/-)) mice displayed a defect in the neutrophilic inflammatory response, associated with impaired induction of RANTES (Regulated upon Activation, Normal T-cell Expressed, and Secreted; also known as CCL5). The subsequent fibrogenic/wound-healing response to both chronic carbon tetrachloride and bile duct ligation induced injury was also impaired and this was associated with deficiencies in the expression of fibrogenic genes, collagen I and alpha-smooth muscle actin, by hepatic stellate cells. We additionally report that c-Rel is required for the normal proliferative regeneration of hepatocytes in response to toxic injury and partial hepatectomy. Absence of c-Rel was associated with blunted and delayed induction of forkhead box M1 (FoxM1) and its downstream targets cyclin B1 and Cdc25C. Furthermore, isolated c-rel(-/-) hepatocytes expressed reduced levels of FoxM1 and a reduced rate of basal and epidermal growth factor-induced DNA synthesis. Chromatin immunoprecipitation revealed that c-Rel binding to the FoxM1 promoter is induced in the regenerating liver. CONCLUSION: c-Rel has multiple functions in the control of liver homeostasis and regeneration and is a transcriptional regulator of FoxM1 and compensatory hepatocyte proliferation.


Assuntos
Hepatite/etiologia , Hepatócitos/citologia , NF-kappa B/fisiologia , Cicatrização/fisiologia , Animais , Proliferação de Células , Regeneração Hepática , Masculino , Camundongos , Camundongos Endogâmicos C57BL
15.
EMBO Rep ; 10(9): 1036-42, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19644500

RESUMO

The tumour suppressor ARF (alternative reading frame), which is mutated or silenced in various tumours, has a crucial role in tumour surveillance to suppress unwarranted cell growth and proliferation. ARF has also been linked to the DNA-damage-induced response of p53 because of its ability to inhibit murine double minute 2 (MDM2). Here, however, we provide genetic evidence for a role of ARF in nucleotide excision repair (NER) that is independent of p53. Cells lacking ARF are deficient in NER. Expression of ARF restores the repair activity, which coincides with increased expression of the damaged-DNA recognition protein xeroderma pigmentosum, complementation group C (XPC). We provide evidence that, by disrupting the interaction between E2F transcription factor 4 (E2F4) and DRTF polypeptide 1 (DP1), ARF reduces the interaction of the E2F4-p130 repressor complex with the promoter of XPC to ensure high-level expression of XPC. Together, our results point to an important 'care-taker'-type tumour-suppression function for ARF in NER through the increased expression of XPC.


Assuntos
Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Reparo do DNA , Proteínas de Ligação a DNA/metabolismo , DNA/metabolismo , Fator de Transcrição E2F4/metabolismo , Animais , Sequência de Bases , Linhagem Celular , Inibidor p16 de Quinase Dependente de Ciclina/deficiência , Inibidor p16 de Quinase Dependente de Ciclina/genética , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica , Camundongos , Camundongos Knockout , Ligação Proteica , Proteínas Proto-Oncogênicas c-mdm2/deficiência , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Dímeros de Pirimidina/metabolismo , Proteína Supressora de Tumor p53/deficiência , Proteína Supressora de Tumor p53/metabolismo
16.
J Biol Chem ; 284(44): 30695-707, 2009 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-19737929

RESUMO

The Forkhead box M1 (FoxM1) transcription factor is critical for expression of the genes essential for G(1)/S transition and mitotic progression. To explore the cell cycle regulation of FoxM1, we examined the phosphorylation profile of FoxM1. Here, we show that the phosphorylated status and the activity of FoxM1 increase as cells progress from S to G(2)/M phases. Moreover, dephosphorylation of FoxM1 coincides with exit from mitosis. Using mass spectrometry, we have identified a new conserved phosphorylation site (Ser-251) within the forkhead domain of FoxM1. Disruption of Ser-251 inhibits phosphorylation of FoxM1 and dramatically decreases its transcriptional activity. We demonstrate that the Ser-251 residue is required for CDK1-dependent phosphorylation of FoxM1 as well as its interaction with the coactivator CREB-binding protein (CBP). Interestingly, the transcriptional activity of the S251A mutant protein remains responsive to activation by overexpressed Polo-like kinase 1 (PLK1). Cells expressing the S251A mutant exhibit reduced expression of the G(2)/M phase genes and impaired mitotic progression. Our results demonstrate that the transcriptional activity of FoxM1 is controlled in a cell cycle-dependent fashion by temporally regulated phosphorylation and dephosphorylation events, and that the phosphorylation at Ser-251 is critical for the activation of FoxM1.


Assuntos
Proteína Quinase CDC2/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Sítios de Ligação , Proteína de Ligação a CREB/metabolismo , Ciclo Celular , Linhagem Celular Tumoral , Sequência Conservada , Proteína Forkhead Box M1 , Humanos , Fosforilação , Serina/metabolismo , Transcrição Gênica
17.
Mol Cell Biol ; 27(3): 1007-16, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17101782

RESUMO

The forkhead box M1 (FoxM1) transcription factor regulates expression of cell cycle genes essential for DNA replication and mitosis during organ repair and cancer progression. Here, we demonstrate that FoxM1-deficient (-/-) mouse embryonic fibroblasts and osteosarcoma U2OS cells depleted in FoxM1 levels by small interfering RNA transfection display increased DNA breaks, as evidenced by immunofluorescence focus staining for phosphospecific histone H2AX. FoxM1-deficient cells also exhibit stimulation of p53 transcriptional activity, as evidenced by increased expression of the p21(cip1) gene. FoxM1-deficient cells display reduced expression of the base excision repair factor X-ray cross-complementing group 1 (XRCC1) and breast cancer-associated gene 2 (BRCA2), the latter of which is involved in homologous recombination repair of DNA double-strand breaks. Furthermore, FoxM1 protein is phosphorylated by checkpoint kinase 2 (Chk2) in response to DNA damage. This phosphorylation of FoxM1 on serine residue 361 caused increased stability of the FoxM1 protein with corresponding increased transcription of XRCC1 and BRCA2 genes, both of which are required for repair of DNA damage. These results identify a novel role for FoxM1 in the transcriptional response during DNA damage/checkpoint signaling and show a novel mechanism by which Chk2 protein regulates expression of DNA repair enzymes.


Assuntos
Proteína BRCA2/metabolismo , Reparo do DNA/genética , Proteínas de Ligação a DNA/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Regulação da Expressão Gênica/genética , Proteínas Serina-Treonina Quinases/metabolismo , Sequência de Aminoácidos , Animais , Proteína BRCA2/genética , Quinase do Ponto de Checagem 2 , Quebras de DNA , Reparo do DNA/efeitos dos fármacos , Reparo do DNA/efeitos da radiação , Proteínas de Ligação a DNA/genética , Etoposídeo/farmacologia , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/enzimologia , Fibroblastos/efeitos da radiação , Proteína Forkhead Box M1 , Fatores de Transcrição Forkhead/química , Fatores de Transcrição Forkhead/deficiência , Humanos , Raios Infravermelhos , Camundongos , Dados de Sequência Molecular , Fosforilação/efeitos dos fármacos , Fosforilação/efeitos da radiação , Serina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/efeitos da radiação , Termodinâmica , Transcrição Gênica/efeitos dos fármacos , Transcrição Gênica/efeitos da radiação , Proteína Supressora de Tumor p53/metabolismo , Raios Ultravioleta , Proteína 1 Complementadora Cruzada de Reparo de Raio-X
18.
Oncogene ; 39(8): 1784-1796, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31740787

RESUMO

Cancers in the oral/head & neck region (HNSCC) are aggressive due to high incidence of recurrence and distant metastasis. One prominent feature of aggressive HNSCC is the presence of severely hypoxic regions in tumors and activation of hypoxia-inducible factors (HIFs). In this study, we report that the XPE gene product DDB2 (damaged DNA binding protein 2), a nucleotide excision repair protein, is upregulated by hypoxia. Moreover, DDB2 inhibits HIF1α in HNSCC cells. It inhibits HIF1α in both normoxia and hypoxia by reducing mRNA expression. Knockdown of DDB2 enhances the expression of angiogenic markers and promotes tumor growth in a xenograft model. We show that DDB2 binds to an upstream promoter element in the HIF1Α gene and promotes histone H3K9 trimethylation around the binding site by recruiting Suv39h1. Also, we provide evidence that DDB2 has a significant suppressive effect on expression of the endogenous markers of hypoxia that are also prognostic indicators in HNSCC. Together, these results describe a new mechanism of hypoxia regulation that opposes expression of HIF1Α mRNA and the hypoxia-response genes.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Carcinoma de Células Escamosas de Cabeça e Pescoço/metabolismo , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologia , Hipóxia Tumoral , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/deficiência , Proteínas de Ligação a DNA/genética , Regulação Neoplásica da Expressão Gênica , Técnicas de Silenciamento de Genes , Humanos , Carcinoma de Células Escamosas de Cabeça e Pescoço/genética
19.
Diabetes Ther ; 11(12): 2791-2827, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33025397

RESUMO

Diabetic kidney disease (DKD) occurs in approximately 20-40% of patients with type 2 diabetes mellitus. Patients with DKD have a higher risk of cardiovascular and all-cause mortality. Angiotensin-converting enzyme inhibitors or angiotensin receptor blockers and antihyperglycemic drugs form the mainstay of DKD management and aim to restrict progression to more severe stages of DKD. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) control hyperglycemia by blocking renal glucose reabsorption in addition to preventing inflammation, thereby improving endothelial function and reducing oxidative stress; consequently, this class of prescription medicines is emerging as an important addition to the therapeutic armamentarium. The EMPA-REG OUTCOME, DECLARE TIMI 58, and CANVAS trials demonstrated the renoprotective effects of SGLT2i, such as restricting decline in glomerular filtration rate, in the progression of albuminuria, and in death due to renal causes. The renoprotection provided by SGLT2i was further confirmed in the CREDENCE study, which showed a 30% reduction in progression of chronic kidney disease, and in the DELIGHT study, which demonstrated a reduction in albuminuria with dapagliflozin compared with placebo (- 21.0%, confidence interval [CI] - 34.1 to - 5.2, p = 0.011). Furthermore, a meta-analysis demonstrated a reduced risk of dialysis, transplantation, or death due to kidney disease (relative risk 0.67; 95% CI 0.52-0.86; p = 0.0019) and a 45% risk reduction in worsening of renal function, end-stage renal disease, or renal death (hazard ratio 0.55, CI 0.48-0.64, p < 0.0001) with SGLT2i, irrespective of baseline estimated glomerular filtration rate. Thus, there is emerging evidence that SGLT2i may be used to curb the mortality and improve the quality of life in patients with DKD. However, clinicians need to effectively select candidates for SGLT2i therapy. In this consensus statement, we have qualitatively synthesized evidence demonstrating the renal effects of SGLT2i and proposed recommendations for optimal use of SGLT2i to effectively manage and delay progression of DKD.

20.
Curr Opin Genet Dev ; 15(1): 42-8, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15661532

RESUMO

Recent genetic studies demonstrate that mice deficient in the forkhead box m1b (Foxm1b) transcription factor are highly resistant to developing hepatocellular carcinoma, which is among the most lethal cancers worldwide. In addition, the Foxm1b transcription factor was identified as a novel inhibitory target of the p19ARF tumor suppressor during early stages of liver tumorigenesis, but p19ARF expression is extinguished in hepatic tumors that develop at later stages. Structure-function studies demonstrate that amino acids 26-46 of the p19ARF protein are sufficient to bind Foxm1b and reduce Foxm1b transcriptional activity by targeting it to the nucleolus. A peptide containing amino acids 24-46 of p19ARF, which was modified to enhance cellular uptake, is an effective inhibitor of Foxm1b transcriptional activity and prevents Foxm1b stimulation of anchorage-independent growth of cells on soft agar. Thus, the p19ARF peptide is an effective inhibitor of Foxm1b and represents a potential therapy for hepatocellular carcinoma.


Assuntos
Carcinoma Hepatocelular/etiologia , Proteínas Nucleares/metabolismo , Fatores de Transcrição/metabolismo , Proteína Supressora de Tumor p14ARF/metabolismo , Animais , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Inibidor p16 de Quinase Dependente de Ciclina , Inibidor de Quinase Dependente de Ciclina p27 , Proteína Forkhead Box M1 , Fatores de Transcrição Forkhead , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/genética , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Camundongos , Proteínas Nucleares/genética , Fatores de Transcrição/genética , Proteína Supressora de Tumor p14ARF/genética , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismo
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