RESUMO
Histone H3.3 glycine 34 to arginine/valine (G34R/V) mutations drive deadly gliomas and show exquisite regional and temporal specificity, suggesting a developmental context permissive to their effects. Here we show that 50% of G34R/V tumors (n = 95) bear activating PDGFRA mutations that display strong selection pressure at recurrence. Although considered gliomas, G34R/V tumors actually arise in GSX2/DLX-expressing interneuron progenitors, where G34R/V mutations impair neuronal differentiation. The lineage of origin may facilitate PDGFRA co-option through a chromatin loop connecting PDGFRA to GSX2 regulatory elements, promoting PDGFRA overexpression and mutation. At the single-cell level, G34R/V tumors harbor dual neuronal/astroglial identity and lack oligodendroglial programs, actively repressed by GSX2/DLX-mediated cell fate specification. G34R/V may become dispensable for tumor maintenance, whereas mutant-PDGFRA is potently oncogenic. Collectively, our results open novel research avenues in deadly tumors. G34R/V gliomas are neuronal malignancies where interneuron progenitors are stalled in differentiation by G34R/V mutations and malignant gliogenesis is promoted by co-option of a potentially targetable pathway, PDGFRA signaling.
Assuntos
Neoplasias Encefálicas/genética , Carcinogênese/genética , Glioma/genética , Histonas/genética , Interneurônios/metabolismo , Mutação/genética , Células-Tronco Neurais/metabolismo , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/genética , Animais , Astrócitos/metabolismo , Astrócitos/patologia , Neoplasias Encefálicas/patologia , Carcinogênese/patologia , Linhagem da Célula , Reprogramação Celular/genética , Cromatina/metabolismo , Embrião de Mamíferos/metabolismo , Epigênese Genética , Regulação Neoplásica da Expressão Gênica , Inativação Gênica , Glioma/patologia , Histonas/metabolismo , Lisina/metabolismo , Camundongos Endogâmicos C57BL , Modelos Biológicos , Gradação de Tumores , Oligodendroglia/metabolismo , Regiões Promotoras Genéticas/genética , Prosencéfalo/embriologia , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Transcrição Gênica , Transcriptoma/genéticaRESUMO
Glycine 34-to-tryptophan (G34W) substitutions in H3.3 arise in approximately 90% of giant cell tumor of bone (GCT). Here, we show H3.3 G34W is necessary for tumor formation. By profiling the epigenome, transcriptome, and secreted proteome of patient samples and tumor-derived cells CRISPR-Cas9-edited for H3.3 G34W, we show that H3.3K36me3 loss on mutant H3.3 alters the deposition of the repressive H3K27me3 mark from intergenic to genic regions, beyond areas of H3.3 deposition. This promotes redistribution of other chromatin marks and aberrant transcription, altering cell fate in mesenchymal progenitors and hindering differentiation. Single-cell transcriptomics reveals that H3.3 G34W stromal cells recapitulate a neoplastic trajectory from a SPP1+ osteoblast-like progenitor population toward an ACTA2+ myofibroblast-like population, which secretes extracellular matrix ligands predicted to recruit and activate osteoclasts. Our findings suggest that H3.3 G34W leads to GCT by sustaining a transformed state in osteoblast-like progenitors, which promotes neoplastic growth, pathologic recruitment of giant osteoclasts, and bone destruction. SIGNIFICANCE: This study shows that H3.3 G34W drives GCT tumorigenesis through aberrant epigenetic remodeling, altering differentiation trajectories in mesenchymal progenitors. H3.3 G34W promotes in neoplastic stromal cells an osteoblast-like progenitor state that enables undue interactions with the tumor microenvironment, driving GCT pathogenesis. These epigenetic changes may be amenable to therapeutic targeting in GCT.See related commentary by Licht, p. 1794.This article is highlighted in the In This Issue feature, p. 1775.
Assuntos
Neoplasias Ósseas/genética , Tumor de Células Gigantes do Osso/genética , Células-Tronco Mesenquimais/metabolismo , Osteoblastos/metabolismo , Diferenciação Celular , HumanosRESUMO
Childhood brain tumors have suspected prenatal origins. To identify vulnerable developmental states, we generated a single-cell transcriptome atlas of >65,000 cells from embryonal pons and forebrain, two major tumor locations. We derived signatures for 191 distinct cell populations and defined the regional cellular diversity and differentiation dynamics. Projection of bulk tumor transcriptomes onto this dataset shows that WNT medulloblastomas match the rhombic lip-derived mossy fiber neuronal lineage and embryonal tumors with multilayered rosettes fully recapitulate a neuronal lineage, while group 2a/b atypical teratoid/rhabdoid tumors may originate outside the neuroectoderm. Importantly, single-cell tumor profiles reveal highly defined cell hierarchies that mirror transcriptional programs of the corresponding normal lineages. Our findings identify impaired differentiation of specific neural progenitors as a common mechanism underlying these pediatric cancers and provide a rational framework for future modeling and therapeutic interventions.
Assuntos
Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patologia , Encéfalo/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Animais , Encéfalo/patologia , Linhagem Celular Tumoral , Humanos , Lactente , Meduloblastoma/genética , Meduloblastoma/patologia , Camundongos , Neoplasias Embrionárias de Células Germinativas/genética , Neoplasias Embrionárias de Células Germinativas/patologia , Fibras Nervosas/patologia , Fibras Nervosas/fisiologia , Prosencéfalo/citologia , Prosencéfalo/embriologia , Tumor Rabdoide/genética , Tumor Rabdoide/patologia , Análise de Célula ÚnicaRESUMO
Our ability to manage acute myeloid leukemia (AML) is limited by our incomplete understanding of the epigenetic disruption central to leukemogenesis, including improper histone methylation. Here we examine 16 histone H3 genes in 434 primary AML samples and identify Q69H, A26P, R2Q, R8H and K27M/I mutations (1.6%), with higher incidence in secondary AML (9%). These mutations occur in pre-leukemic hematopoietic stem cells (HSCs) and exist in the major leukemic clones in patients. They increase the frequency of functional HSCs, alter differentiation, and amplify leukemic aggressiveness. These effects are dependent on the specific mutation. H3K27 mutation increases the expression of genes involved in erythrocyte and myeloid differentiation with altered H3K27 tri-methylation and K27 acetylation. The functional impact of histone mutations is independent of RUNX1 mutation, although they at times co-occur. This study establishes that H3 mutations are drivers of human pre-cancerous stem cell expansion and important early events in leukemogenesis.
Assuntos
Epigenômica , Regulação Leucêmica da Expressão Gênica/fisiologia , Histonas/metabolismo , Leucemia Mieloide Aguda/metabolismo , Animais , Animais Geneticamente Modificados , Antineoplásicos/farmacologia , Sequência de Bases , Células da Medula Óssea , Diferenciação Celular , Transformação Celular Neoplásica , DNA/genética , Drosophila melanogaster/genética , Regulação Leucêmica da Expressão Gênica/efeitos dos fármacos , Hematopoese/fisiologia , Células-Tronco Hematopoéticas/metabolismo , Humanos , Camundongos , Mutação , Neoplasias ExperimentaisRESUMO
High-grade gliomas defined by histone 3 K27M driver mutations exhibit global loss of H3K27 trimethylation and reciprocal gain of H3K27 acetylation, respectively shaping repressive and active chromatin landscapes. We generated tumor-derived isogenic models bearing this mutation and show that it leads to pervasive H3K27ac deposition across the genome. In turn, active enhancers and promoters are not created de novo and instead reflect the epigenomic landscape of the cell of origin. H3K27ac is enriched at repeat elements, resulting in their increased expression, which in turn can be further amplified by DNA demethylation and histone deacetylase inhibitors providing an exquisite therapeutic vulnerability. These agents may therefore modulate anti-tumor immune responses as a therapeutic modality for this untreatable disease.
Assuntos
Neoplasias Encefálicas/metabolismo , Glioma/metabolismo , Histonas/genética , Histonas/metabolismo , Acetilação , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/genética , Linhagem Celular Tumoral , Cromatina/metabolismo , Elementos Facilitadores Genéticos/efeitos dos fármacos , Epigenômica/métodos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Glioma/tratamento farmacológico , Glioma/genética , Inibidores de Histona Desacetilases/farmacologia , Inibidores de Histona Desacetilases/uso terapêutico , Humanos , MutaçãoRESUMO
Lys-27-Met mutations in histone 3 genes (H3K27M) characterize a subgroup of deadly gliomas and decrease genome-wide H3K27 trimethylation. Here we use primary H3K27M tumor lines and isogenic CRISPR-edited controls to assess H3K27M effects in vitro and in vivo. We find that whereas H3K27me3 and H3K27me2 are normally deposited by PRC2 across broad regions, their deposition is severely reduced in H3.3K27M cells. H3K27me3 is unable to spread from large unmethylated CpG islands, while H3K27me2 can be deposited outside these PRC2 high-affinity sites but to levels corresponding to H3K27me3 deposition in wild-type cells. Our findings indicate that PRC2 recruitment and propagation on chromatin are seemingly unaffected by K27M, which mostly impairs spread of the repressive marks it catalyzes, especially H3K27me3. Genome-wide loss of H3K27me3 and me2 deposition has limited transcriptomic consequences, preferentially affecting lowly-expressed genes regulating neurogenesis. Removal of H3K27M restores H3K27me2/me3 spread, impairs cell proliferation, and completely abolishes their capacity to form tumors in mice.
Assuntos
Neoplasias Encefálicas/genética , Cromatina/metabolismo , Glioblastoma/genética , Histonas/genética , Complexo Repressor Polycomb 2/metabolismo , Adolescente , Idoso , Animais , Neoplasias Encefálicas/patologia , Sistemas CRISPR-Cas , Carcinogênese/genética , Linhagem Celular Tumoral , Proliferação de Células/genética , Criança , Ilhas de CpG/genética , Metilação de DNA/genética , Epigênese Genética , Feminino , Edição de Genes/métodos , Regulação Neoplásica da Expressão Gênica , Glioblastoma/patologia , Células HEK293 , Código das Histonas/genética , Histonas/metabolismo , Humanos , Lisina/genética , Masculino , Metionina/genética , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Mutação , Neurogênese/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
In the version of this article originally published, the main-text sentence "In three patients of European ancestry, we identified the germline variant encoding p.Ile97Met in TIM-3, which was homozygous in two (P12 and P13) and heterozygous in one (P15) in the germline but with no TIM-3 plasma membrane expression in the tumor" misstated the identifiers of the two homozygous individuals, which should have been P13 and P14. The error has been corrected in the HTML, PDF and print versions of the paper.
RESUMO
Giant cell lesions of the jaw (GCLJ) are debilitating tumors of unknown origin with limited available therapies. Here, we analyze 58 sporadic samples using next generation or targeted sequencing and report somatic, heterozygous, gain-of-function mutations in KRAS, FGFR1, and p.M713V/I-TRPV4 in 72% (42/58) of GCLJ. TRPV4 p.M713V/I mutations are exclusive to central GCLJ and occur at a critical position adjacent to the cation permeable pore of the channel. Expression of TRPV4 mutants in HEK293 cells leads to increased cell death, as well as increased constitutive and stimulated channel activity, both of which can be prevented using TRPV4 antagonists. Furthermore, these mutations induce sustained activation of ERK1/2, indicating that their effects converge with that of KRAS and FGFR1 mutations on the activation of the MAPK pathway in GCLJ. Our data extend the spectrum of TRPV4 channelopathies and provide rationale for the use of TRPV4 and RAS/MAPK antagonists at the bedside in GCLJ.
Assuntos
Tumor de Células Gigantes do Osso/genética , Neoplasias Maxilomandibulares/genética , Proteínas Proto-Oncogênicas p21(ras)/genética , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , Canais de Cátion TRPV/genética , Adolescente , Adulto , Idoso , Criança , Simulação por Computador , Feminino , Mutação com Ganho de Função , Células HEK293 , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Sistema de Sinalização das MAP Quinases , Masculino , Pessoa de Meia-Idade , Técnicas de Patch-Clamp , Análise de Sequência de DNA , Análise de Sequência de RNA , Sequenciamento do Exoma , Adulto JovemRESUMO
Subcutaneous panniculitis-like T cell lymphoma (SPTCL), a non-Hodgkin lymphoma, can be associated with hemophagocytic lymphohistiocytosis (HLH), a life-threatening immune activation that adversely affects survival1,2. T cell immunoglobulin mucin 3 (TIM-3) is a modulator of immune responses expressed on subgroups of T and innate immune cells. We identify in ~60% of SPTCL cases germline, loss-of-function, missense variants altering highly conserved residues of TIM-3, c.245A>G (p.Tyr82Cys) and c.291A>G (p.Ile97Met), each with specific geographic distribution. The variant encoding p.Tyr82Cys TIM-3 occurs on a potential founder chromosome in patients with East Asian and Polynesian ancestry, while p.Ile97Met TIM-3 occurs in patients with European ancestry. Both variants induce protein misfolding and abrogate TIM-3's plasma membrane expression, leading to persistent immune activation and increased production of inflammatory cytokines, including tumor necrosis factor-α and interleukin-1ß, promoting HLH and SPTCL. Our findings highlight HLH-SPTCL as a new genetic entity and identify mutations causing TIM-3 alterations as a causative genetic defect in SPTCL. While HLH-SPTCL patients with mutant TIM-3 benefit from immunomodulation, therapeutic repression of the TIM-3 checkpoint may have adverse consequences.
Assuntos
Mutação em Linhagem Germinativa , Receptor Celular 2 do Vírus da Hepatite A/genética , Linfo-Histiocitose Hemofagocítica/genética , Linfoma de Células T/genética , Paniculite/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Diagnóstico Diferencial , Feminino , Predisposição Genética para Doença , Humanos , Lactente , Linfo-Histiocitose Hemofagocítica/classificação , Linfo-Histiocitose Hemofagocítica/diagnóstico , Linfoma de Células T/classificação , Linfoma de Células T/diagnóstico , Masculino , Pessoa de Meia-Idade , Paniculite/classificação , Paniculite/diagnóstico , Linhagem , Sequenciamento do Exoma , Adulto JovemRESUMO
Pediatric high-grade gliomas (pHGGs) are aggressive neoplasms representing approximately 20% of brain tumors in children. Current therapies offer limited disease control, and patients have a poor prognosis. Empiric use of targeted therapy, especially at progression, is increasingly practiced despite a paucity of data regarding temporal and therapy-driven genomic evolution in pHGGs. To study the genetic landscape of pHGGs at recurrence, we performed whole exome and methylation analyses on matched primary and recurrent pHGGs from 16 patients. Tumor mutational profiles identified three distinct subgroups. Group 1 (n = 7) harbored known hotspot mutations in Histone 3 (H3) (K27M or G34V) or IDH1 (H3/IDH1 mutants) and co-occurring TP53 or ACVR1 mutations in tumor pairs across the disease course. Group 2 (n = 7), H3/IDH1 wildtype tumor pairs, harbored novel mutations in chromatin modifiers (ZMYND11, EP300 n = 2), all associated with TP53 alterations, or had BRAF V600E mutations (n = 2) conserved across tumor pairs. Group 3 included 2 tumors with NF1 germline mutations. Pairs from primary and relapsed pHGG samples clustered within the same DNA methylation subgroup. ATRX mutations were clonal and retained in H3G34V and H3/IDH1 wildtype tumors, while different genetic alterations in this gene were observed at diagnosis and recurrence in IDH1 mutant tumors. Mutations in putative drug targets (EGFR, ERBB2, PDGFRA, PI3K) were not always shared between primary and recurrence samples, indicating evolution during progression. Our findings indicate that specific key driver mutations in pHGGs are conserved at recurrence and are prime targets for therapeutic development and clinical trials (e.g. H3 post-translational modifications, IDH1, BRAF V600E). Other actionable mutations are acquired or lost, indicating that re-biopsy at recurrence will provide better guidance for effective targeted therapy of pHGGs.
Assuntos
Neoplasias Encefálicas/genética , Glioma/genética , Recidiva Local de Neoplasia/genética , Adolescente , Adulto , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patologia , Criança , Pré-Escolar , Metilação de DNA , Epigênese Genética , Feminino , Regulação Neoplásica da Expressão Gênica , Glioma/metabolismo , Glioma/patologia , Humanos , Masculino , Mutação , Gradação de Tumores , Recidiva Local de Neoplasia/metabolismo , Recidiva Local de Neoplasia/patologia , Estudos Retrospectivos , Adulto JovemRESUMO
Gain-of-function mutations in histone 3 (H3) variants are found in a substantial proportion of pediatric high-grade gliomas (pHGG), often in association with TP53 loss and platelet-derived growth factor receptor alpha (PDGFRA) amplification. Here, we describe a somatic mouse model wherein H3.3K27M and Trp53 loss alone are sufficient for neoplastic transformation if introduced in utero. H3.3K27M-driven lesions are clonal, H3K27me3 depleted, Olig2 positive, highly proliferative, and diffusely spreading, thus recapitulating hallmark molecular and histopathological features of pHGG. Addition of wild-type PDGFRA decreases latency and increases tumor invasion, while ATRX knockdown is associated with more circumscribed tumors. H3.3K27M-tumor cells serially engraft in recipient mice, and preliminary drug screening reveals mutation-specific vulnerabilities. Overall, we provide a faithful H3.3K27M-pHGG model which enables insights into oncohistone pathogenesis and investigation of future therapies.
Assuntos
Células-Tronco Embrionárias/metabolismo , Glioma/genética , Histonas/genética , Células-Tronco Neurais/metabolismo , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/genética , Proteína Supressora de Tumor p53/genética , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Transformação Celular Neoplásica/genética , Regulação Neoplásica da Expressão Gênica , Glioma/metabolismo , Glioma/patologia , Humanos , Camundongos , Mutação , Gradação de Tumores , Invasividade Neoplásica , Interferência de RNA , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Proteína Nuclear Ligada ao X/genética , Proteína Nuclear Ligada ao X/metabolismoRESUMO
Human papillomavirus (HPV)-negative head and neck squamous cell carcinomas (HNSCCs) are deadly and common cancers. Recent genomic studies implicate multiple genetic pathways, including cell signaling, cell cycle and immune evasion, in their development. Here we analyze public data sets and uncover a previously unappreciated role of epigenome deregulation in the genesis of 13% of HPV-negative HNSCCs. Specifically, we identify novel recurrent mutations encoding p.Lys36Met (K36M) alterations in multiple H3 histone genes. histones. We further validate the presence of these alterations in multiple independent HNSCC data sets and show that, along with previously described NSD1 mutations, they correspond to a specific DNA methylation cluster. The K36M substitution and NSD1 defects converge on altering methylation of histone H3 at K36 (H3K36), subsequently blocking cellular differentiation and promoting oncogenesis. Our data further indicate limited redundancy for NSD family members in HPV-negative HNSCCs and suggest a potential role for impaired H3K36 methylation in their development. Further investigation of drugs targeting chromatin regulators is warranted in HPV-negative HNSCCs driven by aberrant H3K36 methylation.
Assuntos
Carcinoma de Células Escamosas/genética , Metilação de DNA/genética , Neoplasias de Cabeça e Pescoço/genética , Histonas/genética , Carcinogênese/genética , Diferenciação Celular/genética , Epigênese Genética/genética , Histona Metiltransferases , Histona-Lisina N-Metiltransferase , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Mutação/genética , Proteínas Nucleares/genética , Papillomaviridae/patogenicidade , Infecções por Papillomavirus/genética , Carcinoma de Células Escamosas de Cabeça e PescoçoRESUMO
Diffuse Intrinsic Pontine Gliomas (DIPGs) are deadly paediatric brain tumours where needle biopsies help guide diagnosis and targeted therapies. To address spatial heterogeneity, here we analyse 134 specimens from various neuroanatomical structures of whole autopsy brains from nine DIPG patients. Evolutionary reconstruction indicates histone 3 (H3) K27M--including H3.2K27M--mutations potentially arise first and are invariably associated with specific, high-fidelity obligate partners throughout the tumour and its spread, from diagnosis to end-stage disease, suggesting mutual need for tumorigenesis. These H3K27M ubiquitously-associated mutations involve alterations in TP53 cell-cycle (TP53/PPM1D) or specific growth factor pathways (ACVR1/PIK3R1). Later oncogenic alterations arise in sub-clones and often affect the PI3K pathway. Our findings are consistent with early tumour spread outside the brainstem including the cerebrum. The spatial and temporal homogeneity of main driver mutations in DIPG implies they will be captured by limited biopsies and emphasizes the need to develop therapies specifically targeting obligate oncohistone partnerships.
Assuntos
Neoplasias do Tronco Encefálico/genética , Carcinogênese/genética , Regulação Neoplásica da Expressão Gênica , Glioma/genética , Histonas/genética , Mutação , Receptores de Ativinas Tipo I/genética , Receptores de Ativinas Tipo I/metabolismo , Autopsia , Mapeamento Encefálico , Tronco Encefálico/metabolismo , Tronco Encefálico/patologia , Neoplasias do Tronco Encefálico/metabolismo , Neoplasias do Tronco Encefálico/patologia , Carcinogênese/metabolismo , Carcinogênese/patologia , Cérebro/metabolismo , Cérebro/patologia , Criança , Classe Ia de Fosfatidilinositol 3-Quinase , Evolução Clonal , Glioma/metabolismo , Glioma/patologia , Histonas/metabolismo , Humanos , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Fosfoproteínas Fosfatases/genética , Fosfoproteínas Fosfatases/metabolismo , Proteína Fosfatase 2C , Transdução de Sinais , Técnicas Estereotáxicas , Fatores de Tempo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
BACKGROUND: Increased consumption of folic acid is prevalent, leading to concerns about negative consequences. The effects of folic acid on the liver, the primary organ for folate metabolism, are largely unknown. Methylenetetrahydrofolate reductase (MTHFR) provides methyl donors for S-adenosylmethionine (SAM) synthesis and methylation reactions. OBJECTIVE: Our goal was to investigate the impact of high folic acid intake on liver disease and methyl metabolism. DESIGN: Folic acid-supplemented diet (FASD, 10-fold higher than recommended) and control diet were fed to male Mthfr(+/+) and Mthfr(+/-) mice for 6 mo to assess gene-nutrient interactions. Liver pathology, folate and choline metabolites, and gene expression in folate and lipid pathways were examined. RESULTS: Liver and spleen weights were higher and hematologic profiles were altered in FASD-fed mice. Liver histology revealed unusually large, degenerating cells in FASD Mthfr(+/-) mice, consistent with nonalcoholic fatty liver disease. High folic acid inhibited MTHFR activity in vitro, and MTHFR protein was reduced in FASD-fed mice. 5-Methyltetrahydrofolate, SAM, and SAM/S-adenosylhomocysteine ratios were lower in FASD and Mthfr(+/-) livers. Choline metabolites, including phosphatidylcholine, were reduced due to genotype and/or diet in an attempt to restore methylation capacity through choline/betaine-dependent SAM synthesis. Expression changes in genes of one-carbon and lipid metabolism were particularly significant in FASD Mthfr(+/-) mice. The latter changes, which included higher nuclear sterol regulatory element-binding protein 1, higher Srepb2 messenger RNA (mRNA), lower farnesoid X receptor (Nr1h4) mRNA, and lower Cyp7a1 mRNA, would lead to greater lipogenesis and reduced cholesterol catabolism into bile. CONCLUSIONS: We suggest that high folic acid consumption reduces MTHFR protein and activity levels, creating a pseudo-MTHFR deficiency. This deficiency results in hepatocyte degeneration, suggesting a 2-hit mechanism whereby mutant hepatocytes cannot accommodate the lipid disturbances and altered membrane integrity arising from changes in phospholipid/lipid metabolism. These preliminary findings may have clinical implications for individuals consuming high-dose folic acid supplements, particularly those who are MTHFR deficient.
Assuntos
Suplementos Nutricionais/intoxicação , Inibidores Enzimáticos/intoxicação , Ácido Fólico/intoxicação , Homocistinúria/etiologia , Metabolismo dos Lipídeos , Fígado/metabolismo , Metilenotetra-Hidrofolato Redutase (NADPH2)/deficiência , Espasticidade Muscular/etiologia , Hepatopatia Gordurosa não Alcoólica/etiologia , Animais , Regulação da Expressão Gênica , Heterozigoto , Homocistinúria/metabolismo , Homocistinúria/patologia , Homocistinúria/fisiopatologia , Lipogênese , Fígado/patologia , Fígado/fisiopatologia , Masculino , Metilação , Metilenotetra-Hidrofolato Redutase (NADPH2)/antagonistas & inibidores , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Metilenotetra-Hidrofolato Redutase (NADPH2)/metabolismo , Camundongos Endogâmicos BALB C , Camundongos Mutantes , Espasticidade Muscular/metabolismo , Espasticidade Muscular/patologia , Espasticidade Muscular/fisiopatologia , Mutação , Tamanho do Órgão , Transtornos Psicóticos/etiologia , Transtornos Psicóticos/metabolismo , Transtornos Psicóticos/patologia , Transtornos Psicóticos/fisiopatologia , Organismos Livres de Patógenos EspecíficosRESUMO
SCOPE: Inadequate folate intake increases risk for colorectal cancer. We previously showed that low-folate diets induced intestinal tumors in BALB/c mice, but not in C57BL/6 mice. We suggested that DNA damage, altered methylation, and reduced apoptosis could contribute to tumorigenesis in this model. METHODS AND RESULTS: To identify genes involved in tumorigenesis, we compared gene expression profiles in preneoplastic intestine of BALB/c and C57BL/6 mice-fed low folate. We identified 74 upregulated and 90 downregulated genes in BALB/c compared to C57BL/6 mice. We validated decreased expression of Bcmo1 and increased expression of Aldh1a, which would be expected to upregulate the peroxisome proliferator-activated receptor alpha (PPARA) pathway, and confirmed the expected upregulation of several Ppara downstream genes. We verified, in BALB/c mice, reduced expression of Sprr2a, a gene that increases resistance to oxidative damage, and of two oncosuppressors (Bmp5 and Arntl). Low folate increased Ppara and Aldh1a1 expression, and decreased Bcmo1, Sprr2a, and Bmp5 expression in BALB/c, compared to BALB/c on control diets. Bcmo1, Ppara, and Bmp5 showed differential DNA methylation related to strain, diet, and/or Mthfr genotype. CONCLUSION: Disturbed regulation of the retinoid/PPARA pathway, which influences oxidative damage, and altered expression of tumor suppressors may contribute to intestinal tumorigenesis induced by low-folate intake.
Assuntos
Transformação Celular Neoplásica/efeitos dos fármacos , Metilação de DNA/efeitos dos fármacos , Ácido Fólico/sangue , Intestinos/efeitos dos fármacos , PPAR alfa/genética , Aldeído Desidrogenase/genética , Aldeído Desidrogenase/metabolismo , Família Aldeído Desidrogenase 1 , Animais , Proteína Morfogenética Óssea 5/genética , Proteína Morfogenética Óssea 5/metabolismo , Transformação Celular Neoplásica/metabolismo , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Proteínas Ricas em Prolina do Estrato Córneo/genética , Proteínas Ricas em Prolina do Estrato Córneo/metabolismo , Dano ao DNA/efeitos dos fármacos , Dieta , Feminino , Deficiência de Ácido Fólico/genética , Deficiência de Ácido Fólico/patologia , Expressão Gênica , Genótipo , Mucosa Intestinal/metabolismo , Neoplasias Intestinais/genética , Neoplasias Intestinais/patologia , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Metilenotetra-Hidrofolato Redutase (NADPH2)/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Análise em Microsséries , PPAR alfa/metabolismo , Retinal Desidrogenase , Retinoides/análise , Retinoides/metabolismo , Regulação para Cima , beta-Caroteno 15,15'-Mono-Oxigenase/efeitos dos fármacos , beta-Caroteno 15,15'-Mono-Oxigenase/metabolismoRESUMO
SCOPE: Genetic or nutritional disturbances in folate metabolism lead to hyperhomocysteinemia and adverse reproductive outcomes. Folate-dependent homocysteine remethylation is required for methylation reactions and may influence choline/betaine metabolism. Hyperhomocysteinemia has been suggested to play a role in inflammation. The goal of this study was to determine whether folate-related pregnancy complications could be due to altered expression of some inflammatory mediators or due to disturbances in methylation intermediates. METHODS AND RESULTS: Pregnant mice with or without a deficiency of methylenetetrahydrofolate reductase (MTHFR) were fed control diets or folate-deficient (FD) diets; tissues were collected at embryonic day 14.5. FD decreased plasma phosphocholine and increased plasma glycerophosphocholine and lysophosphatidylcholine. Liver betaine, phosphocholine, and S-adenosylmethionine:S-adenosylhomocysteine ratios were reduced in FD. In liver, spleen, and placenta, the lowest levels of apolipoprotein AI (ApoAI) were observed in Mthfr(+/-) mice fed FD. Increased interferon-gamma (IFN-γ) was observed in spleen and placentae due to FD or Mthfr genotype. Plasma homocysteine correlated negatively with liver and spleen ApoAI, and positively with IFN-γ. CONCLUSION: Low dietary folate or Mthfr deficiency during pregnancy may result in adverse pregnancy outcomes by altering expression of the inflammatory mediators ApoAI and IFN-γ in spleen and placenta. Disturbances in choline metabolism or methylation reactions may also play a role.
Assuntos
Apolipoproteína A-I/metabolismo , Ácido Fólico/administração & dosagem , Interferon gama/metabolismo , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Complicações na Gravidez/genética , Animais , Betaína/análise , Betaína/metabolismo , Colina/análise , Colina/metabolismo , Dieta , Feminino , Deficiência de Ácido Fólico/complicações , Deficiência de Ácido Fólico/patologia , Homocisteína/sangue , Homocistinúria/complicações , Homocistinúria/patologia , Fígado/metabolismo , Fígado/patologia , Masculino , Metilação , Metilenotetra-Hidrofolato Redutase (NADPH2)/deficiência , Metilenotetra-Hidrofolato Redutase (NADPH2)/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Transgênicos , Espasticidade Muscular/complicações , Espasticidade Muscular/patologia , Placenta/metabolismo , Placenta/patologia , Gravidez , Complicações na Gravidez/metabolismo , Transtornos Psicóticos/complicações , Transtornos Psicóticos/patologia , S-Adenosil-Homocisteína/análise , S-Adenosil-Homocisteína/metabolismo , S-Adenosilmetionina/análise , S-Adenosilmetionina/metabolismo , Baço/metabolismo , Baço/patologiaRESUMO
Low dietary choline or deficiency of methylenetetrahydrofolate reductase (Mthfr) leads to hyperhomocysteinemia (Hhcy) and adverse reproductive outcomes. Homocysteine reduces synthesis of ApoAI, the major lipoprotein in HDL-cholesterol; ApoAI is regulated by PPARα and has antiinflammatory properties. Our aim was to determine whether pregnancy complications due to genetic or nutritional deficiencies in 1-carbon metabolism could relate to dysregulation of ApoAI and inflammatory mediators. We fed pregnant mice, with or without a deficiency of Mthfr, control or choline-deficient (ChDD) diets for 10-12 wk and examined levels of ApoAI, PPARα, IFNγ, and IL-10. ApoAI mRNA was reduced in livers of Mthfr(+/-) mice and ApoAI protein was reduced due to Mthfr deficiency or choline deficiency in liver and plasma. Placental ApoAI protein was also reduced due to Mthfr genotype or choline-deficient diet and in developmentally delayed embryos. Reduced liver PPARα expression (mRNA and protein) was observed in ChDD-fed mice and was associated with increased methylation of a CpG dinucleotide in its promoter. Hepatic IFNγ increased due to genotype, and placental IFNγ was higher in Mthfr(+/-) ChDD-fed dams compared to Mthfr(+/+) mice fed ChDD or Mthfr(+/-) mice fed CD. IL-10 was reduced in livers of ChDD-fed mice. We propose that a deficiency of dietary choline or Mthfr leads to Hhcy and reduced expression of maternal ApoAI, with reduced ApoAI transfer to embryo. Disturbances in 1-carbon metabolism also reduce maternal PPARα expression, possibly through promoter hypermethylation, and increase IFNγ and decrease IL-10 levels. This disturbance of the T helper (Th1) (IFNγ):Th2 (IL-10) ratio and the increase in inflammatory mediators may contribute to pregnancy complications.
Assuntos
Apolipoproteína A-I/metabolismo , Interferon gama/metabolismo , Interleucina-10/metabolismo , PPAR alfa/metabolismo , Complicações na Gravidez/etiologia , Animais , Apolipoproteína A-I/sangue , Apolipoproteína A-I/genética , Deficiência de Colina/complicações , Deficiência de Colina/metabolismo , Metilação de DNA , Feminino , Expressão Gênica , Homocisteína/sangue , Homocisteína/metabolismo , Homocistinúria/complicações , Homocistinúria/genética , Homocistinúria/metabolismo , Hiper-Homocisteinemia/complicações , Hiper-Homocisteinemia/metabolismo , Mediadores da Inflamação/sangue , Mediadores da Inflamação/metabolismo , Fígado/metabolismo , Masculino , Metilenotetra-Hidrofolato Redutase (NADPH2)/deficiência , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Metilenotetra-Hidrofolato Redutase (NADPH2)/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Espasticidade Muscular/complicações , Espasticidade Muscular/genética , Espasticidade Muscular/metabolismo , PPAR alfa/genética , Placenta/metabolismo , Gravidez , Complicações na Gravidez/genética , Complicações na Gravidez/metabolismo , Regiões Promotoras Genéticas , Transtornos Psicóticos/complicações , Transtornos Psicóticos/genética , Transtornos Psicóticos/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
BACKGROUND: Despite extensive research on mild methylenetetrahydrofolate reductase (MTHFR) deficiency and low dietary folate in different disorders, the association of these metabolic disturbances with a variety of congenital defects and pregnancy complications remains controversial. In this study we investigated the effects of MTHFR and dietary folate deficiency at 10.5 days post coitum (dpc) in our mouse model of mild MTHFR deficiency. METHODS: Mthfr +/+ and +/- female mice were fed a control or folic acid-deficient diet for 6 weeks, then mated with Mthfr +/- males. At 10.5 dpc, embryos were examined and placentae were collected for histologic evaluation. RESULTS: Maternal MTHFR and folate deficiencies resulted in increased developmental delays and smaller embryos. We also observed a low frequency of a variety of embryonic defects in the experimental groups, such as neural tube, heart looping, and turning defects; these results mimic the low incidence and multifactorial nature of these anomalies in humans. Folate-deficient mice also had increased embryonic losses and severe placental defects, including placental abruption and disturbed patterning of placental layers. Folate-deficient placentae had decreased ApoA-I expression, and there was a trend toward a negative correlation between ApoA-I expression with maternal homocysteine concentrations. CONCLUSIONS: Our study provides biological evidence linking maternal MTHFR and dietary folate deficiencies to adverse pregnancy outcomes in mice. It underscores the importance of folate not only in reducing the incidence of early embryonic defects, but also in the prevention of developmental delays and placental abnormalities that may increase susceptibility to other defects and to reproductive complications.
Assuntos
Suplementos Nutricionais , Desenvolvimento Embrionário , Ácido Fólico/farmacologia , Metilenotetra-Hidrofolato Redutase (NADPH2)/deficiência , Placenta/anormalidades , Placenta/enzimologia , Complexo Vitamínico B/farmacologia , Animais , Apolipoproteína A-I/biossíntese , Perda do Embrião/enzimologia , Embrião de Mamíferos/enzimologia , Feminino , Cardiopatias Congênitas/enzimologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Mutantes , Defeitos do Tubo Neural/enzimologia , GravidezRESUMO
AIMS: Statins can ameliorate atherosclerosis by inhibition of cholesterol biosynthesis or by modulation of inflammation. In earlier work, we showed that homocysteine (Hcy) reduced synthesis of apolipoprotein A-I (ApoA-I). Our goal in this study was to determine whether Hcy could interfere with the ability of simvastatin to increase ApoA-I synthesis or to modify statin-dependent regulation of inflammatory factors. METHODS AND RESULTS: Human HepG2 hepatocarcinoma cells and murine RAW264.7 macrophages were treated with simvastatin, with and without Hcy, to examine the expression of ApoA-I and nuclear factor-kappaB (NF-kappaB) or the NF-kappaB target, inducible nitric-oxide synthase (iNOS), respectively. Mice with methylenetetrahydrofolate reductase (Mthfr) deficiency, an animal model of hyperhomocysteinemia, were administered simvastatin (in diets or by injection) for in vivo assessment of these interactions. In HepG2 cells, Hcy reduced the statin-dependent increases in ApoA-I protein, mRNA, and ApoA-I promoter activity. In RAW264.7 macrophages, simvastatin decreased, whereas Hcy increased, the expression of pro-inflammatory NF-kappaB protein; in the presence of both Hcy and simvastatin, the pro-inflammatory effect of Hcy prevailed. Hcy increased mRNA levels of iNOS in the macrophage line; the combination of Hcy and simvastatin resulted in a trend towards greater induction. In mouse studies, simvastatin decreased cholesterol levels, but levels of ApoA-I in Mthfr-deficient mice remained lower than those in Mthfr(+/+) mice. Simvastatin injection increased iNOS protein and mRNA levels in peripheral blood of hyperhomocysteinemic Mthfr-deficient mice, but not in Mthfr(+/+) mice. The drug also increased MTHFR protein in cells and mouse liver, an effect that was modified by Hcy. CONCLUSION: These findings provide a link between statins and folate-dependent Hcy metabolism, and suggest that Hcy interferes with some anti-atherogenic and anti-inflammatory properties of simvastatin. Our work may have clinical relevance for hyperhomocysteinemic individuals on statin therapy.