Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 15 de 15
Filtrar
1.
Cell ; 150(5): 948-60, 2012 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-22939622

RESUMO

Heterochromatin serves important functions, protecting genome integrity and stabilizing gene expression programs. Although the Suv39h methyltransferases (KMTs) are known to ensure pericentric H3K9me3 methylation, the mechanisms that initiate and maintain mammalian heterochromatin organization remain elusive. We developed a biochemical assay and used in vivo analyses in mouse embryonic fibroblasts to identify Prdm3 and Prdm16 as redundant H3K9me1-specific KMTs that direct cytoplasmic H3K9me1 methylation. The H3K9me1 is converted in the nucleus to H3K9me3 by the Suv39h enzymes to reinforce heterochromatin. Simultaneous depletion of Prdm3 and Prdm16 abrogates H3K9me1 methylation, prevents Suv39h-dependent H3K9me3 trimethylation, and derepresses major satellite transcription. Most strikingly, DNA-FISH and electron microscopy reveal that combined impairment of Prdm3 and Prdm16 results in disintegration of heterochromatic foci and disruption of the nuclear lamina. Our data identify Prdm3 and Prdm16 as H3K9me1 methyltransferases and expose a functional framework in which anchoring to the nuclear periphery helps maintain the integrity of mammalian heterochromatin.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Heterocromatina , Histona-Lisina N-Metiltransferase/metabolismo , Fatores de Transcrição/metabolismo , Animais , Proteínas de Ligação a DNA/genética , Fibroblastos/metabolismo , Técnicas de Inativação de Genes , Células HeLa , Histona-Lisina N-Metiltransferase/genética , Histonas/metabolismo , Humanos , Proteína do Locus do Complexo MDS1 e EVI1 , Camundongos , Lâmina Nuclear/metabolismo , Proto-Oncogenes , Fatores de Transcrição/genética
2.
Annu Rev Cell Dev Biol ; 26: 471-501, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-19575672

RESUMO

Genetic screens in Drosophila have been instrumental in distinguishing approximately 390 loci involved in position effect variegation and heterochromatin stabilization. Most of the identified genes [so-called Su(var) and E(var) genes] are also conserved in mammals, where more than 50 of their gene products are known to localize to constitutive heterochromatin. From these proteins, approximately 12 core heterochromatin components can be inferred. In addition, there are approximately 30 additional Su(var) and 10 E(var) factors that can, under distinct developmental options, interchange with constitutive heterochromatin and participate in the partitioning of the genome into repressed and active chromatin domains. A significant fraction of the Su(var) and E(var) factors are enzymes that respond to environmental and metabolic signals, thereby allowing both the variation and propagation of epigenetic states to a dynamic chromatin template. Moreover, the misregulation of human SU(VAR) and E(VAR) function can advance cancer and many other human diseases including more complex disorders. As such, mammalian Su(var) and E(var) genes and their products provide a rich source of novel targets for diagnosis of and pharmaceutical intervention in many human diseases.


Assuntos
Cromatina/metabolismo , Proteínas de Ligação a DNA/metabolismo , Metiltransferases/metabolismo , Proteínas Repressoras/metabolismo , Animais , Proteínas de Ligação a DNA/genética , Heterocromatina , Humanos , Metiltransferases/genética , Proteínas Repressoras/genética
3.
Nucleic Acids Res ; 49(10): 5568-5587, 2021 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-33999208

RESUMO

Heterochromatin has essential functions in maintaining chromosome structure, in protecting genome integrity and in stabilizing gene expression programs. Heterochromatin is often nucleated by underlying DNA repeat sequences, such as major satellite repeats (MSR) and long interspersed nuclear elements (LINE). In order to establish heterochromatin, MSR and LINE elements need to be transcriptionally competent and generate non-coding repeat RNA that remain chromatin associated. We explored whether these heterochromatic RNA, similar to DNA and histones, may be methylated, particularly for 5-methylcytosine (5mC) or methyl-6-adenosine (m6A). Our analysis in mouse ES cells identifies only background level of 5mC but significant enrichment for m6A on heterochromatic RNA. Moreover, MSR transcripts are a novel target for m6A RNA modification, and their m6A RNA enrichment is decreased in ES cells that are mutant for Mettl3 or Mettl14, which encode components of a central RNA methyltransferase complex. Importantly, MSR transcripts that are partially deficient in m6A RNA methylation display impaired chromatin association and have a reduced potential to form RNA:DNA hybrids. We propose that m6A modification of MSR RNA will enhance the functions of MSR repeat transcripts to stabilize mouse heterochromatin.


Assuntos
DNA/metabolismo , Heterocromatina , RNA/metabolismo , Adenosina/análogos & derivados , Adenosina/metabolismo , Animais , Metilação , Camundongos , Células-Tronco Embrionárias Murinas , Sequências de Repetição em Tandem
4.
Proc Natl Acad Sci U S A ; 117(25): 14251-14258, 2020 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-32513732

RESUMO

Nearly 50% of mouse and human genomes are composed of repetitive sequences. Transcription of these sequences is tightly controlled during development to prevent genomic instability, inappropriate gene activation and other maladaptive processes. Here, we demonstrate an integral role for H1 linker histones in silencing repetitive elements in mouse embryonic stem cells. Strong H1 depletion causes a profound de-repression of several classes of repetitive sequences, including major satellite, LINE-1, and ERV. Activation of repetitive sequence transcription is accompanied by decreased H3K9 trimethylation of repetitive sequence chromatin. H1 linker histones interact directly with Suv39h1, Suv39h2, and SETDB1, the histone methyltransferases responsible for H3K9 trimethylation of chromatin within these regions, and stimulate their activity toward chromatin in vitro. However, we also implicate chromatin compaction mediated by H1 as an additional, dominant repressive mechanism for silencing of repetitive major satellite sequences. Our findings elucidate two distinct, H1-mediated pathways for silencing heterochromatin.


Assuntos
Cromatina/metabolismo , Histonas/metabolismo , Sequências Repetitivas de Ácido Nucleico/fisiologia , Animais , Epigenômica , Heterocromatina/metabolismo , Histona-Lisina N-Metiltransferase/metabolismo , Metilação , Metiltransferases/metabolismo , Camundongos , Células-Tronco Embrionárias Murinas/metabolismo , Proteínas Repressoras/metabolismo
5.
Nat Commun ; 15(1): 3880, 2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38719804

RESUMO

Correlative evidence has suggested that the methyl-CpG-binding protein MeCP2 contributes to the formation of heterochromatin condensates via liquid-liquid phase separation. This interpretation has been reinforced by the observation that heterochromatin, DNA methylation and MeCP2 co-localise within prominent foci in mouse cells. The findings presented here revise this view. MeCP2 localisation is independent of heterochromatin as MeCP2 foci persist even when heterochromatin organisation is disrupted. Additionally, MeCP2 foci fail to show hallmarks of phase separation in live cells. Importantly, we find that mouse cellular models are highly atypical as MeCP2 distribution is diffuse in most mammalian species, including humans. Notably, MeCP2 foci are absent in Mus spretus which is a mouse subspecies lacking methylated satellite DNA repeats. We conclude that MeCP2 has no intrinsic tendency to form condensates and its localisation is independent of heterochromatin. Instead, the distribution of MeCP2 in the nucleus is primarily determined by global DNA methylation patterns.


Assuntos
Metilação de DNA , Heterocromatina , Proteína 2 de Ligação a Metil-CpG , Proteína 2 de Ligação a Metil-CpG/metabolismo , Proteína 2 de Ligação a Metil-CpG/genética , Heterocromatina/metabolismo , Animais , Camundongos , Humanos , Núcleo Celular/metabolismo , Ligação Proteica , DNA/metabolismo , DNA Satélite/metabolismo , DNA Satélite/genética , Separação de Fases
6.
Nat Commun ; 12(1): 4359, 2021 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-34272378

RESUMO

Histone H3 lysine 9 (H3K9) methylation is a central epigenetic modification that defines heterochromatin from unicellular to multicellular organisms. In mammalian cells, H3K9 methylation can be catalyzed by at least six distinct SET domain enzymes: Suv39h1/Suv39h2, Eset1/Eset2 and G9a/Glp. We used mouse embryonic fibroblasts (MEFs) with a conditional mutation for Eset1 and introduced progressive deletions for the other SET domain genes by CRISPR/Cas9 technology. Compound mutant MEFs for all six SET domain lysine methyltransferase (KMT) genes lack all H3K9 methylation states, derepress nearly all families of repeat elements and display genomic instabilities. Strikingly, the 6KO H3K9 KMT MEF cells no longer maintain heterochromatin organization and have lost electron-dense heterochromatin. This is a compelling analysis of H3K9 methylation-deficient mammalian chromatin and reveals a definitive function for H3K9 methylation in protecting heterochromatin organization and genome integrity.


Assuntos
Fibroblastos/metabolismo , Heterocromatina/metabolismo , Histona-Lisina N-Metiltransferase/metabolismo , Histonas/metabolismo , Lisina/metabolismo , Animais , Sistemas CRISPR-Cas , Sequenciamento de Cromatina por Imunoprecipitação , Cromatografia Líquida , Desmetilação , Epigênese Genética , Fibroblastos/enzimologia , Deleção de Genes , Heterocromatina/enzimologia , Heterocromatina/genética , Heterocromatina/ultraestrutura , Histona-Lisina N-Metiltransferase/genética , Hibridização in Situ Fluorescente , Espectrometria de Massas , Metilação , Camundongos , Microscopia Eletrônica de Transmissão , Mutação , Processamento de Proteína Pós-Traducional/genética , RNA-Seq , Sequências Repetitivas de Ácido Nucleico/genética , Retroelementos/genética , Transdução de Sinais/genética
7.
Cancer Res ; 66(18): 9202-10, 2006 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-16982764

RESUMO

We tested the hypothesis that cell invasiveness and tumorigenesis are driven by hypomethylation of genes involved in tumor progression. Highly invasive human prostate cancer cells PC-3 were treated with either the methyl donor S-adenosylmethionine (SAM) or methyl DNA-binding domain protein 2 antisense oligonucleotide (MBD2-AS). Both treatments resulted in a dose- and time-dependent inhibition of key genes, such as urokinase-type plasminogen activator (uPA), matrix metalloproteinase-2 (MMP-2), and vascular endothelial growth factor expression to decrease tumor cell invasion in vitro. No change in the levels of expression of genes already known to be methylated in late-stage prostate cancer cells, such as glutathione S-transferase P1 and androgen receptor, was seen. Inoculation of PC-3 cells pretreated with SAM and MBD2-AS into the flank of male BALB/c nu/nu mice resulted in the development of tumors of significantly smaller volume compared with animals inoculated with PC-3 cells treated with vehicle alone or MBD2 scrambled oligonucleotide. Immunohistochemical analysis of tumors showed the ability of SAM and MBD2-AS to significantly decrease tumoral uPA and MMP-2 expression along with levels of angiogenesis and survival pathway signaling molecules. Bisulfite sequencing analysis of tumoral genomic DNA showed that inhibition of both uPA and MMP-2 expression was due to methylation of their 5' regulatory region. These studies support the hypothesis that DNA hypomethylation controls the activation of multiple tumor-promoting genes and provide valuable insight into developing novel therapeutic strategies against this common disease, which target the demethylation machinery.


Assuntos
Transformação Celular Neoplásica/genética , Metilação de DNA , Neoplasias da Próstata/genética , Neoplasias da Próstata/terapia , Animais , Linhagem Celular Tumoral , Transformação Celular Neoplásica/patologia , Proteínas de Ligação a DNA/biossíntese , Proteínas de Ligação a DNA/deficiência , Proteínas de Ligação a DNA/genética , Regulação para Baixo , Terapia Genética/métodos , Humanos , Masculino , Metaloproteinase 2 da Matriz/biossíntese , Metaloproteinase 2 da Matriz/genética , Camundongos , Camundongos Endogâmicos BALB C , Invasividade Neoplásica , Neovascularização Patológica/genética , Neovascularização Patológica/terapia , Oligonucleotídeos Antissenso/genética , Ativadores de Plasminogênio/biossíntese , Ativadores de Plasminogênio/deficiência , Ativadores de Plasminogênio/genética , Neoplasias da Próstata/irrigação sanguínea , Neoplasias da Próstata/patologia , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , S-Adenosilmetionina/farmacologia , Transfecção , Fator A de Crescimento do Endotélio Vascular/biossíntese , Fator A de Crescimento do Endotélio Vascular/deficiência , Fator A de Crescimento do Endotélio Vascular/genética , Ensaios Antitumorais Modelo de Xenoenxerto
8.
Elife ; 62017 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-28760199

RESUMO

The Suv39h1 and Suv39h2 histone lysine methyltransferases are hallmark enzymes at mammalian heterochromatin. We show here that the mouse Suv39h2 enzyme differs from Suv39h1 by containing an N-terminal basic domain that facilitates retention at mitotic chromatin and provides an additional affinity for major satellite repeat RNA. To analyze an RNA-dependent interaction with chromatin, we purified native nucleosomes from mouse ES cells and detect that Suv39h1 and Suv39h2 exclusively associate with poly-nucleosomes. This association was attenuated upon RNaseH incubation and entirely lost upon RNaseA digestion of native chromatin. Major satellite repeat transcripts remain chromatin-associated and have a secondary structure that favors RNA:DNA hybrid formation. Together, these data reveal an RNA-mediated mechanism for the stable chromatin interaction of the Suv39h KMT and suggest a function for major satellite non-coding RNA in the organization of an RNA-nucleosome scaffold as the underlying structure of mouse heterochromatin.


Assuntos
DNA/metabolismo , Heterocromatina/metabolismo , Histona-Lisina N-Metiltransferase/metabolismo , Metiltransferases/metabolismo , Hibridização de Ácido Nucleico , RNA/metabolismo , Sequências Repetitivas de Ácido Nucleico , Proteínas Repressoras/metabolismo , Animais , Camundongos , Nucleossomos/metabolismo
9.
Cancer Res ; 63(9): 2072-8, 2003 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-12727822

RESUMO

Prostate cancer is a common malignancy affecting men, which is often associated with skeletal metastases resulting in significant morbidity and mortality. In this hormone-dependent cancer, low levels of a prostate secretory protein of 94 amino acids (PSP-94) are associated with advanced disease stage. In the current study, we have examined the effect of PSP-94 on prostate cancer growth and experimental metastases to the skeleton. For these studies, MatLyLu rat prostate cancer cells were transfected with full-length cDNA encoding parathyroid hormone-related protein [PTHrP (MatLyLu-PTHrP cells)], which is known to be the major pathogenetic factor for malignancy-associated hypercalcemia. MatLyLu-PTHrP cells were inoculated s.c. into the right flank or via intracardiac route into the left ventricle of syngeneic male Copenhagen rats. Intracardiac inoculation of MatLyLu cells routinely results in the development of tumors in the lumbar vertebrae, resulting in hind-limb paralysis. Animals were infused with different doses of PSP-94 (0.1, 1.0, and 10.0 micro g/kg/day) starting on the day of tumor cell inoculation. Time of hind-limb paralysis and tumor volume were determined, and comparison was made between PSP-94-treated animals and control animals receiving vehicle alone. At the end of the study, animals were sacrificed, and plasma calcium, plasma PTHrP, and tumor PTHrP levels were determined. Whereas the highest dose of PSP-94 caused a modest but statistically significant delay in the development of hind-limb paralysis, a marked dose-dependent decrease in primary tumor volume was seen in experimental animals receiving PSP-94 due to its ability to promote tumor cell apoptosis. Furthermore, whereas control animals routinely developed hypercalcemia due to PTHrP production, treatment with PSP-94 led to a near normalization of plasma calcium and a marked reduction in PTHrP production as determined by radioimmunoassay and immunohistochemistry. Collectively, these results demonstrate the ability of PSP-94 to be an effective treatment modality for prostate cancer, where decrease in plasma PTHrP and calcium levels can serve as useful biochemical markers for monitoring the efficacy of this novel antitumor agent.


Assuntos
Hipercalcemia/tratamento farmacológico , Neoplasias da Próstata/sangue , Neoplasias da Próstata/tratamento farmacológico , Proteínas Secretadas pela Próstata/farmacologia , Animais , Apoptose/efeitos dos fármacos , Neoplasias Ósseas/prevenção & controle , Neoplasias Ósseas/secundário , Cálcio/sangue , Divisão Celular/efeitos dos fármacos , Divisão Celular/fisiologia , Humanos , Hipercalcemia/sangue , Masculino , Proteína Relacionada ao Hormônio Paratireóideo , Hormônios Peptídicos/sangue , Hormônios Peptídicos/genética , Neoplasias da Próstata/patologia , Ratos , Transfecção , Células Tumorais Cultivadas
10.
Cancer Res ; 64(15): 5370-7, 2004 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-15289344

RESUMO

In previous studies, we have shown that prostate secretory protein (PSP-94) can reduce prostate cancer growth in vivo. In the current study, we identified the amino acid sequence of PSP-94 that is required for eliciting this response. For these studies, we used rat prostate cancer Mat Ly Lu cells overexpressing parathyroid hormone-related protein (PTHrP), which is the main pathogenetic factor responsible for hypercalcemia of malignancy. Synthetic peptides corresponding to amino acids 7-21 (PCK721), 31-45 (PCK3145), and 76-94 (PCK7694) of PSP-94 were synthesized. Only PCK3145 showed a significant reduction in tumor cell proliferation. For in vivo studies, syngenic male Copenhagen rats were inoculated s.c. with Mat Ly Lu cells overexpressing PTHrP into the right flank or into the left ventricle via intracardiac injection, which results in experimental metastases to the lumbar vertebrae causing hind-limb paralysis. Animals were infused with different doses (1, 10, and 100 microg/kg/day) of peptides for 15 days, and the effect of these treatments on tumor volume, skeletal metastases, or development of hind-limb paralysis was determined. Treatment with PCK3145 resulted in a dose-dependent decrease in tumor volume and delay in the development of skeletal metastases. Bone histomorphometry showed that after intracardiac inoculation of tumor cells, the highest dose of PCK3145 (100 microg/kg/day) resulted in reducing skeletal tumor burden, which delayed the development of hind-limb paralysis. Treatment with PCK3145 led to reduction of plasma calcium and PTHrP levels and a significant decrease in PTHrP levels in the primary tumors and in vertebrae of experimental animals. These effects of PCK3145 were due to its ability to promote tumor cell apoptosis. Collectively, the results of these studies have demonstrated the ability of a small peptide derived from PSP-94 to reduce tumor volume and experimental skeletal metastases-results that will be highly beneficial in the continued development of this peptide as a novel therapeutic agent for patients with hormone refractory, late-stage prostate cancer.


Assuntos
Neoplasias Ósseas/prevenção & controle , Membro Posterior/patologia , Hipercalcemia/tratamento farmacológico , Fragmentos de Peptídeos/uso terapêutico , Neoplasias da Próstata/tratamento farmacológico , Proteínas Secretadas pela Próstata/uso terapêutico , Animais , Apoptose/efeitos dos fármacos , Neoplasias Ósseas/secundário , Cálcio/metabolismo , Divisão Celular/efeitos dos fármacos , Humanos , Hipercalcemia/sangue , Masculino , Proteína Relacionada ao Hormônio Paratireóideo/metabolismo , Neoplasias da Próstata/sangue , Neoplasias da Próstata/patologia , Ratos , Células Tumorais Cultivadas
11.
Br J Pharmacol ; 172(11): 2769-81, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25631332

RESUMO

BACKGROUND AND PURPOSE: DNA hypomethylation was previously implicated in metastasis. In the present study, we examined whether methyl supplementation with the universal methyl donor S-adenosylmethionine (SAM) inhibits prostate cancer associated skeletal metastasis. EXPERIMENTAL APPROACH: Highly invasive human prostate cancer cells PC-3 and DU-145 were treated with vehicle alone, S-adenosylhomocysteine (SAH) or SAM and their effects on tumour cell proliferation, invasion, migration and colony formation were monitored. For in vivo studies, control (SAH) and SAM-treated PC-3 cells were injected into the tibia of Fox chase SCID mice and skeletal lesions were determined by X-ray and µCT. To understand possible mechanisms involved, we delineated the effect of SAM on the genome-wide methylation profile of PC-3 cells. KEY RESULTS: Treatment with SAM resulted in a dose-dependent inhibition of tumour cell proliferation, invasion, cell migration, colony formation and cell cycle characteristics. Animals injected with 250 µM SAM-treated cells developed significantly smaller skeletal lesions, which were associated with increases in bone volume to tumour volume ratio and connectivity density as well as decreased trabecular spacing. Genome-wide methylation analysis showed differential methylation in several key signalling pathways implicated in prostate cancer including the signal transducer and activator of transcription 3 (STAT3) pathway. A selective STAT3 inhibitor decreased tumour cell invasion, effects which were less pronounced as compared with SAM. CONCLUSIONS AND IMPLICATIONS: These studies provide a possible mechanism for the role of DNA demethylation in the development of skeletal metastasis and a rationale for the use of hypermethylation pharmacological agents to impede the development and progression of skeletal metastasis.


Assuntos
Adenocarcinoma/genética , Neoplasias Ósseas/genética , Proliferação de Células/efeitos dos fármacos , Metilação de DNA/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Neoplasias da Próstata/genética , S-Adenosilmetionina/farmacologia , Adenocarcinoma/secundário , Animais , Neoplasias Ósseas/secundário , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Movimento Celular/genética , Proliferação de Células/genética , Humanos , Técnicas In Vitro , Masculino , Camundongos , Camundongos SCID , Invasividade Neoplásica/genética , Metástase Neoplásica/genética , Transplante de Neoplasias , Neoplasias da Próstata/patologia , Tíbia/diagnóstico por imagem , Tíbia/efeitos dos fármacos , Microtomografia por Raio-X
12.
Nat Struct Mol Biol ; 19(10): 1023-30, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22983563

RESUMO

Heterochromatin is important for genome integrity and stabilization of gene-expression programs. We have identified the transcription factors Pax3 and Pax9 as redundant regulators of mouse heterochromatin, as they repress RNA output from major satellite repeats by associating with DNA within pericentric heterochromatin. Simultaneous depletion of Pax3 and Pax9 resulted in dramatic derepression of major satellite transcripts, persistent impairment of heterochromatic marks and defects in chromosome segregation. Genome-wide analyses of methylated histone H3 at Lys9 showed enrichment at intergenic major satellite repeats only when these sequences retained intact binding sites for Pax and other transcription factors. Additionally, bioinformatic interrogation of all histone methyltransferase Suv39h-dependent heterochromatic repeat regions in the mouse genome revealed a high concordance with the presence of transcription factor binding sites. These data define a general model in which reiterated arrangement of transcription factor binding sites within repeat sequences is an intrinsic mechanism of the formation of heterochromatin.


Assuntos
Heterocromatina/metabolismo , Fatores de Transcrição Box Pareados/metabolismo , Animais , Sequência de Bases , Sítios de Ligação , Ciclo Celular/genética , Segregação de Cromossomos , DNA Satélite/metabolismo , Fibroblastos/metabolismo , Genoma , Heterocromatina/genética , Histonas/metabolismo , Lisina/metabolismo , Metilação , Metiltransferases/genética , Metiltransferases/metabolismo , Camundongos , Camundongos Mutantes , Dados de Sequência Molecular , Fator de Transcrição PAX3 , Fator de Transcrição PAX5/genética , Fator de Transcrição PAX5/metabolismo , Fator de Transcrição PAX7/genética , Fator de Transcrição PAX7/metabolismo , Fator de Transcrição PAX9 , Fatores de Transcrição Box Pareados/genética , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo
13.
Cell Metab ; 14(2): 161-72, 2011 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-21803287

RESUMO

Epigenetic modifications are thought to be important for gene expression changes during development and aging. However, besides the Sir2 histone deacetylase in somatic tissues and H3K4 trimethylation in germlines, there is scant evidence implicating epigenetic regulations in aging. The insulin/IGF-1 signaling (IIS) pathway is a major life span regulatory pathway. Here, we show that progressive increases in gene expression and loss of H3K27me3 on IIS components are due, at least in part, to increased activity of the H3K27 demethylase UTX-1 during aging. RNAi of the utx-1 gene extended the mean life span of C. elegans by ~30%, dependent on DAF-16 activity and not additive in daf-2 mutants. The loss of utx-1 increased H3K27me3 on the Igf1r/daf-2 gene and decreased IIS activity, leading to a more "naive" epigenetic state. Like stem cell reprogramming, our results suggest that reestablishment of epigenetic marks lost during aging might help "reset" the developmental age of animal cells.


Assuntos
Envelhecimento , Caenorhabditis elegans/enzimologia , Histona Desmetilases/metabolismo , Transdução de Sinais , Animais , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Regulação para Baixo , Fatores de Transcrição Forkhead , Histona Desmetilases/genética , Insulina/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Interferência de RNA , RNA Interferente Pequeno , Receptor de Insulina/genética , Fatores de Transcrição/metabolismo
14.
Anticancer Drugs ; 16(10): 1045-51, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16222145

RESUMO

This review focuses on the promising roles of prostate secretory protein of 94 amino acids (PSP-94) and one of its derived peptides (PCK3145) as potential therapeutic modalities for prostate cancer and its associated complications. Evaluation of these compounds was carried out in vitro and in vivo using syngeneic models of rat prostate cancer. Overproduction of parathyroid hormone-related protein (PTHrP) results in the development of hypercalcemia of malignancy in several malignancies including prostate cancer. In order to evaluate the effect of PSP-94 and PCK3145 on prostate cancer progression, the rat Dunning R3227 MatLyLu cell line transfected with full-length cDNA encoding PTHrP (MatLyLu-PTHrP) was used. As the main pathogenetic factor of hypercalcemia of malignancy, overexpression of PTHrP was aimed at mimicking the hypercalcemic nature seen in patients suffering from late-stage cancer. In vitro studies showed that PSP-94 and PCK3145 can cause a dose-dependent inhibition in the growth of MatLyLu-PTHrP cells. For in vivo studies, male Copenhagen rats were inoculated either s.c. into the right flank or directly into the left ventricle via intracardiac (i.c.) inoculation with MatLyLu-PTHrP cells. In these models, s.c. injection of MatLyLu cells results in the development of primary tumor growth, whereas i.c. inoculation routinely results in the development of experimental skeletal metastases in the lumbar vertebrae causing hind-limb paralysis. Administration of PSP-94 and PCK3145 into tumor-bearing animals resulted in a dose-dependent inhibition of primary tumor growth, and tumoral and plasma PTHrP levels, and in the reduction of plasma calcium levels. Additionally, treatment with PSP-94 or PCK3145 caused an inhibition of skeletal metastases resulting in a significant delay in the development of hind-limb paralysis. Interestingly, equimolar concentrations of PCK3145 were shown to be more effective in delaying the development of experimental skeletal metastases as compared to PSP-94. One of the possible mechanisms of action of these modalities is through the induction of apoptosis which was observed by both in-vitro and in-vivo analyses of MatLyLu-PTHrP cells and tumors. Several intracellular mechanisms can also be involved in inhibiting PTHrP production and anti-tumor effects of PSP-94 and PCK3145. Collectively, these studies warrant the continued clinical development of these agents as therapeutic agents for patients with hormone-refractory prostate cancer.


Assuntos
Antineoplásicos/uso terapêutico , Neoplasias Ósseas/prevenção & controle , Fragmentos de Peptídeos/uso terapêutico , Neoplasias da Próstata/tratamento farmacológico , Proteínas Secretadas pela Próstata/uso terapêutico , Animais , Neoplasias Ósseas/secundário , Cálcio/sangue , Linhagem Celular Tumoral , Humanos , Masculino , Proteína Relacionada ao Hormônio Paratireóideo/sangue , Neoplasias da Próstata/patologia , Ratos
15.
Cancer ; 101(6): 1345-56, 2004 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-15316903

RESUMO

BACKGROUND: Wnt-1 and beta-catenin expression levels play an important role in several malignancies. The authors determined the level of production of Wnt-1 and beta-catenin in normal and malignant human prostate carcinoma cell lines. Surgical pathology specimens from primary prostatic adenocarcinoma, lymph node metastases, and skeletal metastases were used to establish a correlation between the level of Wnt-1/beta-catenin expression, Gleason score, serum prostate-specific antigen (PSA) status, and androgen receptor (AR) status. METHODS: Immunohistochemical analysis was used to investigate the expression of Wnt-1 and beta-catenin in human prostate carcinoma cell lines and in paraffin embedded sections of archival samples from 67 patients with prostate carcinoma. Comparison was made with the expression of tumoral AR and lymph node and skeletal metastases. These results were used to establish a correlation with the clinicopathologic status of patients with prostate carcinoma. RESULTS: Levels of both Wnt-1 and beta-catenin were low in normal prostate cells and were expressed highly in human prostate carcinoma cell lines. Wnt-1 and cytoplasmic/nuclear beta-catenin expression was observed in 52% and 34%, respectively, of primary prostate carcinoma specimens. High levels of expression of Wnt-1 and beta-catenin were seen in 77% of lymph node metastases and in 85% of skeletal metastases. These increased levels of expression were related directly to the Gleason score and to serum PSA levels in these patients. Maximum levels of Wnt-1 and beta-catenin production were observed in skeletal metastases, whereas normal prostatic tissue failed to exhibit any detectable nuclear staining for beta-catenin. CONCLUSIONS: High levels of Wnt-1 and beta-catenin expression were associated with advanced, metastatic, hormone-refractory prostate carcinoma, in which they can serve as markers of disease progression.


Assuntos
Adenocarcinoma/metabolismo , Proteínas do Citoesqueleto/metabolismo , Neoplasias da Próstata/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Transativadores/metabolismo , Regulação para Cima , Adenocarcinoma/patologia , Idoso , Androgênios/metabolismo , Neoplasias Ósseas/secundário , Regulação Neoplásica da Expressão Gênica , Humanos , Imuno-Histoquímica , Metástase Linfática , Masculino , Prognóstico , Antígeno Prostático Específico , Neoplasias da Próstata/patologia , Células Tumorais Cultivadas , Proteínas Wnt , Proteína Wnt1 , beta Catenina
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA