RESUMO
A delicate equilibrium of WNT agonists and antagonists in the intestinal stem cell (ISC) niche is critical to maintaining the ISC compartment, as it accommodates the rapid renewal of the gut lining. Disruption of this balance by mutations in the tumour suppressor gene APC, which are found in approximately 80% of all human colon cancers, leads to unrestrained activation of the WNT pathway1,2. It has previously been established that Apc-mutant cells have a competitive advantage over wild-type ISCs3. Consequently, Apc-mutant ISCs frequently outcompete all wild-type stem cells within a crypt, thereby reaching clonal fixation in the tissue and initiating cancer formation. However, whether the increased relative fitness of Apc-mutant ISCs involves only cell-intrinsic features or whether Apc mutants are actively involved in the elimination of their wild-type neighbours remains unresolved. Here we show that Apc-mutant ISCs function as bona fide supercompetitors by secreting WNT antagonists, thereby inducing differentiation of neighbouring wild-type ISCs. Lithium chloride prevented the expansion of Apc-mutant clones and the formation of adenomas by rendering wild-type ISCs insensitive to WNT antagonists through downstream activation of WNT by inhibition of GSK3ß. Our work suggests that boosting the fitness of healthy cells to limit the expansion of pre-malignant clones may be a powerful strategy to limit the formation of cancers in high-risk individuals.
Assuntos
Proteína da Polipose Adenomatosa do Colo/genética , Competição entre as Células , Genes APC , Neoplasias Intestinais/genética , Neoplasias Intestinais/patologia , Mutação , Adenoma/genética , Adenoma/metabolismo , Adenoma/patologia , Proteína da Polipose Adenomatosa do Colo/deficiência , Animais , Diferenciação Celular/genética , Feminino , Glicogênio Sintase Quinase 3 beta/antagonistas & inibidores , Humanos , Neoplasias Intestinais/metabolismo , Cloreto de Lítio/farmacologia , Masculino , Camundongos , Organoides/citologia , Organoides/metabolismo , Organoides/patologia , Proteínas Wnt/antagonistas & inibidores , Proteínas Wnt/metabolismoRESUMO
BACKGROUND & AIMS: Colorectal cancer (CRC) is thought to arise when the cumulative mutational burden within colonic crypts exceeds a certain threshold that leads to clonal expansion and ultimately neoplastic transformation. Therefore, quantification of the fixation and subsequent expansion of somatic mutations in normal epithelium is key to understanding colorectal cancer initiation. The aim of the present study was to determine how advantaged expansions can be accommodated in the human colon. METHODS: Immunohistochemistry was used to visualize loss of the cancer driver KDM6A in formalin-fixed paraffin-embedded (FFPE) normal human colonic epithelium. Combining microscopy with neural network-based image analysis, we determined the frequencies of KDM6A-mutant crypts and fission/fusion intermediates as well as the spatial distribution of clones. Mathematical modeling then defined the dynamics of their fixation and expansion. RESULTS: Interpretation of the age-related behavior of KDM6A-negative clones revealed significant competitive advantage in intracrypt dynamics as well as a 5-fold increase in crypt fission rate. This was not accompanied by an increase in crypt fusion. Mathematical modeling of crypt spacing identifies evidence for a crypt diffusion process. We define the threshold fission rate at which diffusion fails to accommodate new crypts, which can be exceeded by KRAS activating mutations. CONCLUSIONS: Advantaged gene mutations in KDM6A expand dramatically by crypt fission but not fusion. The crypt diffusion process enables accommodation of the additional crypts up to a threshold value, beyond which polyp growth may occur. The fission rate associated with KRAS mutations offers a potential explanation for KRAS-initiated polyps.
Assuntos
Proliferação de Células , Transformação Celular Neoplásica/genética , Pólipos do Colo/genética , Neoplasias Colorretais/genética , Células Epiteliais/patologia , Histona Desmetilases/genética , Mucosa Intestinal/patologia , Mutação , Células-Tronco Neoplásicas/patologia , Proteínas Proto-Oncogênicas p21(ras)/genética , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Transformação Celular Neoplásica/metabolismo , Transformação Celular Neoplásica/patologia , Pólipos do Colo/metabolismo , Pólipos do Colo/patologia , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Difusão , Células Epiteliais/metabolismo , Feminino , Histona Desmetilases/metabolismo , Humanos , Mucosa Intestinal/metabolismo , Masculino , Pessoa de Meia-Idade , Modelos Biológicos , Células-Tronco Neoplásicas/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Adulto JovemRESUMO
BACKGROUND & AIMS: In homeostasis, intestinal cell fate is controlled by balanced gradients of morphogen signaling. The bone morphogenetic protein (BMP) pathway has a physiological, prodifferentiation role, predominantly inferred through previous experimental pathway inactivation. Intestinal regeneration is underpinned by dedifferentiation and cell plasticity, but the signaling pathways that regulate this adaptive reprogramming are not well understood. We assessed the BMP signaling landscape and investigated the impact and therapeutic potential of pathway manipulation in homeostasis and regeneration. METHODS: A novel mouse model was generated to assess the effect of the autocrine Bmp4 ligand on individual secretory cell fate. We spatiotemporally mapped BMP signaling in mouse and human regenerating intestine. Transgenic models were used to explore the functional impact of pathway manipulation on stem cell fate and intestinal regeneration. RESULTS: In homeostasis, ligand exposure reduced proliferation, expedited terminal differentiation, abrogated secretory cell survival, and prevented dedifferentiation. After ulceration, physiological attenuation of BMP signaling arose through upregulation of the secreted antagonist Grem1 from topographically distinct populations of fibroblasts. Concomitant expression supported functional compensation after Grem1 deletion from tissue-resident cells. BMP pathway manipulation showed that antagonist-mediated BMP attenuation was obligatory but functionally submaximal, because regeneration was impaired or enhanced by epithelial overexpression of Bmp4 or Grem1, respectively. Mechanistically, Bmp4 abrogated regenerative stem cell reprogramming despite a convergent impact of YAP/TAZ on cell fate in remodeled wounds. CONCLUSIONS: BMP signaling prevents epithelial dedifferentiation, and pathway attenuation through stromal Grem1 upregulation was required for adaptive reprogramming in intestinal regeneration. This intercompartmental antagonism was functionally submaximal, raising the possibility of therapeutic pathway manipulation in inflammatory bowel disease.
Assuntos
Proteína Morfogenética Óssea 4/metabolismo , Colite/metabolismo , Colo/metabolismo , Células Epiteliais/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Mucosa Intestinal/metabolismo , Intestino Delgado/metabolismo , Lesões Experimentais por Radiação/metabolismo , Regeneração , Animais , Comunicação Autócrina , Proteína Morfogenética Óssea 4/genética , Diferenciação Celular , Proliferação de Células , Colite/genética , Colite/patologia , Colo/patologia , Células Epiteliais/patologia , Feminino , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/genética , Mucosa Intestinal/patologia , Intestino Delgado/patologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Lesões Experimentais por Radiação/genética , Lesões Experimentais por Radiação/patologia , Reepitelização , Transdução de SinaisRESUMO
Cancer evolution is predominantly studied by focusing on differences in the genetic characteristics of malignant cells within tumors. However, the spatiotemporal dynamics of clonal outgrowth that underlie evolutionary trajectories remain largely unresolved. Here, we sought to unravel the clonal dynamics of colorectal cancer (CRC) expansion in space and time by using a color-based clonal tracing method. This method involves lentiviral red-green-blue (RGB) marking of cell populations, which enabled us to track individual cells and their clonal outgrowth during tumor initiation and growth in a xenograft model. We found that clonal expansion largely depends on the location of a clone, as small clones reside in the center and large clones mostly drive tumor growth at the border. These dynamics are recapitulated in a computational model, which confirms that the clone position within a tumor rather than cell-intrinsic features, is crucial for clonal outgrowth. We also found that no significant clonal loss occurs during tumor growth and clonal dispersal is limited in most models. Our results imply that, in addition to molecular features of clones such as (epi-)genetic differences between cells, clone location and the geometry of tumor growth are crucial for clonal expansion. Our findings suggest that either microenvironmental signals on the tumor border or differences in physical properties within the tumor, are major contributors to explain heterogeneous clonal expansion. Thus, this study provides further insights into the dynamics of solid tumor growth and progression, as well as the origins of tumor cell heterogeneity in a relevant model system.
Assuntos
Neoplasias Colorretais/patologia , Animais , Linhagem da Célula , Células Clonais , Neoplasias Colorretais/genética , Feminino , Xenoenxertos , Humanos , Camundongos , Camundongos Nus , Transplante de Neoplasias , Análise Espaço-TemporalRESUMO
The rapid cell turnover of the intestinal epithelium is achieved from small numbers of stem cells located in the base of glandular crypts. These stem cells have been variously described as rapidly cycling or quiescent. A functional arrangement of stem cells that reconciles both of these behaviours has so far been difficult to obtain. Alternative explanations for quiescent cells have been that they act as a parallel or reserve population that replace rapidly cycling stem cells periodically or after injury; their exact nature remains unknown. Here we show mouse intestinal quiescent cells to be precursors that are committed to mature into differentiated secretory cells of the Paneth and enteroendocrine lineage. However, crucially we find that after intestinal injury they are capable of extensive proliferation and can give rise to clones comprising the main epithelial cell types. Thus, quiescent cells can be recalled to the stem-cell state. These findings establish quiescent cells as an effective clonogenic reserve and provide a motivation for investigating their role in pathologies such as colorectal cancers and intestinal inflammation.
Assuntos
Linhagem da Célula , Células-Tronco Multipotentes/citologia , Células-Tronco Multipotentes/metabolismo , Celulas de Paneth/citologia , Celulas de Paneth/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Animais , Biomarcadores/análise , Biomarcadores/metabolismo , Diferenciação Celular , Divisão Celular , Separação Celular , Células Clonais/citologia , Células Clonais/metabolismo , Neoplasias Intestinais/patologia , Intestinos/citologia , Intestinos/lesões , Intestinos/patologia , Camundongos , Regeneração , Coloração e Rotulagem , Nicho de Células-TroncoRESUMO
Genetic screens in simple model organisms have identified many of the key components of the conserved signal transduction pathways that are oncogenic when misregulated. Here, we identify H37N21.1 as a gene that regulates vulval induction in let-60(n1046gf), a strain with a gain-of-function mutation in the Caenorhabditis elegans Ras orthologue, and show that somatic deletion of Nrbp1, the mouse orthologue of this gene, results in an intestinal progenitor cell phenotype that leads to profound changes in the proliferation and differentiation of all intestinal cell lineages. We show that Nrbp1 interacts with key components of the ubiquitination machinery and that loss of Nrbp1 in the intestine results in the accumulation of Sall4, a key mediator of stem cell fate, and of Tsc22d2. We also reveal that somatic loss of Nrbp1 results in tumourigenesis, with haematological and intestinal tumours predominating, and that nuclear receptor binding protein 1 (NRBP1) is downregulated in a range of human tumours, where low expression correlates with a poor prognosis. Thus NRBP1 is a conserved regulator of cell fate, that plays an important role in tumour suppression.
Assuntos
Homeostase/fisiologia , Intestinos/fisiologia , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Receptores Citoplasmáticos e Nucleares/fisiologia , Células-Tronco/fisiologia , Proteínas Supressoras de Tumor/genética , Proteínas de Transporte Vesicular/fisiologia , Animais , Proteínas de Transporte/análise , Diferenciação Celular/genética , Diferenciação Celular/fisiologia , Proliferação de Células , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Proteínas de Ligação a DNA/análise , Feminino , Deleção de Genes , Humanos , Intestinos/citologia , Peptídeos e Proteínas de Sinalização Intracelular/genética , Masculino , Camundongos , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patologia , Oxirredutases , Prognóstico , Receptores Citoplasmáticos e Nucleares/genética , Células-Tronco/citologia , Fatores de Transcrição/análise , Proteínas Supressoras de Tumor/fisiologia , Ubiquitinação/genética , Ubiquitinação/fisiologia , Proteínas de Transporte Vesicular/genéticaRESUMO
In the established model of mammalian cell cycle control, the retinoblastoma protein (Rb) functions to restrict cells from entering S phase by binding and sequestering E2f activators (E2f1, E2f2 and E2f3), which are invariably portrayed as the ultimate effectors of a transcriptional program that commit cells to enter and progress through S phase. Using a panel of tissue-specific cre-transgenic mice and conditional E2f alleles we examined the effects of E2f1, E2f2 and E2f3 triple deficiency in murine embryonic stem cells, embryos and small intestines. We show that in normal dividing progenitor cells E2f1-3 function as transcriptional activators, but contrary to the current view, are dispensable for cell division and instead are necessary for cell survival. In differentiating cells E2f1-3 function in a complex with Rb as repressors to silence E2f targets and facilitate exit from the cell cycle. The inactivation of Rb in differentiating cells resulted in a switch of E2f1-3 from repressors to activators, leading to the superactivation of E2f responsive targets and ectopic cell divisions. Loss of E2f1-3 completely suppressed these phenotypes caused by Rb deficiency. This work contextualizes the activator versus repressor functions of E2f1-3 in vivo, revealing distinct roles in dividing versus differentiating cells and in normal versus cancer-like cell cycles.
Assuntos
Diferenciação Celular , Fatores de Transcrição E2F/metabolismo , Células-Tronco Embrionárias/citologia , Células-Tronco Embrionárias/metabolismo , Regulação da Expressão Gênica , Proteínas Repressoras/metabolismo , Alelos , Animais , Apoptose , Ciclo Celular/genética , Ciclo Celular/fisiologia , Proliferação de Células , Fatores de Transcrição E2F/deficiência , Fatores de Transcrição E2F/genética , Fator de Transcrição E2F1/deficiência , Fator de Transcrição E2F1/genética , Fator de Transcrição E2F1/metabolismo , Fator de Transcrição E2F2/deficiência , Fator de Transcrição E2F2/genética , Fator de Transcrição E2F2/metabolismo , Fator de Transcrição E2F3/deficiência , Fator de Transcrição E2F3/genética , Fator de Transcrição E2F3/metabolismo , Embrião de Mamíferos/citologia , Embrião de Mamíferos/metabolismo , Feminino , Intestino Delgado/citologia , Intestino Delgado/metabolismo , Camundongos , Camundongos Transgênicos , Proteínas Repressoras/deficiência , Proteínas Repressoras/genética , Proteína do Retinoblastoma/deficiência , Proteína do Retinoblastoma/metabolismoRESUMO
BACKGROUND & AIMS: Chronic inflammatory illnesses are debilitating and recurrent conditions associated with significant comorbidities, including an increased risk of developing cancer. Extensive tissue remodeling is a hallmark of such illnesses, and is both a consequence and a mediator of disease progression. Despite previous characterization of epithelial and stromal remodeling during inflammatory bowel disease, a complete understanding of its impact on disease progression is lacking. METHODS: A comprehensive proteomic pipeline using data-independent acquisition was applied to decellularized colon samples from the Muc2 knockout (Muc2KO) mouse model of colitis for an in-depth characterization of extracellular matrix remodeling. Unique proteomic profiles of the matrisomal landscape were extracted from prepathologic and overt colitis. Integration of proteomics and transcriptomics data sets extracted from the same murine model produced network maps describing the orchestrating role of matrisomal proteins in tissue remodeling during the progression of colitis. RESULTS: The in-depth proteomic workflow used here allowed the addition of 34 proteins to the known colon matrisomal signature. Protein signatures of prepathologic and pathologic colitic states were extracted, differentiating the 2 states by expression of small leucine-rich proteoglycans. We outlined the role of this class and other matrisomal proteins in tissue remodeling during colitis, as well as the potential for coordinated regulation of cell types by matrisomal ligands. CONCLUSIONS: Our work highlights a central role for matrisomal proteins in tissue remodeling during colitis and defines orchestrating nodes that can be exploited in the selection of therapeutic targets.
Assuntos
Colite , Proteômica , Camundongos , Animais , Matriz Extracelular/metabolismo , Colite/patologia , Doença Crônica , Progressão da DoençaRESUMO
According to the current model of adult epidermal homeostasis, skin tissue is maintained by two discrete populations of progenitor cells: self-renewing stem cells; and their progeny, known as transit amplifying cells, which differentiate after several rounds of cell division. By making use of inducible genetic labelling, we have tracked the fate of a representative sample of progenitor cells in mouse tail epidermis at single-cell resolution in vivo at time intervals up to one year. Here we show that clone-size distributions are consistent with a new model of homeostasis involving only one type of progenitor cell. These cells are found to undergo both symmetric and asymmetric division at rates that ensure epidermal homeostasis. The results raise important questions about the potential role of stem cells on tissue maintenance in vivo.
Assuntos
Linhagem da Célula , Células Epidérmicas , Homeostase , Células-Tronco/citologia , Animais , Diferenciação Celular , Divisão Celular , Células Clonais/citologia , Camundongos , Modelos BiológicosRESUMO
Organoids, combined with genetic editing strategies, have the potential to offer rapid and efficient investigation of gene function in many models of human disease. However, to date, the editing efficiency of organoids with the use of non-viral electroporation methods has only been up to 30%, with implications for the subsequent need for selection, including turnaround time and exhaustion or adaptation of the organoid population. Here, we describe an efficient method for intestinal organoid editing using a ribonucleoprotein-based CRISPR approach. Editing efficiencies of up to 98% in target genes were robustly achieved across different gut anatomical locations and developmental timepoints from multiple patient samples with no observed off-target editing. The method allowed us to study the effect of loss of the tumour suppressor gene PTEN in normal human intestinal cells. Analysis of PTEN-deficient organoids defined phenotypes that likely relate to its tumour suppressive function in vivo, such as a proliferative advantage and increased organoid budding. Transcriptional profiling revealed differential expression of genes in pathways commonly known to be associated with PTEN loss, including mTORC1 activation.
Assuntos
Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Ribonucleoproteínas , Humanos , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Ribonucleoproteínas/metabolismo , Edição de Genes/métodos , Organoides/metabolismo , Sistemas CRISPR-Cas/genéticaRESUMO
We identify the sodium leak channel non-selective protein (NALCN) as a key regulator of cancer metastasis and nonmalignant cell dissemination. Among 10,022 human cancers, NALCN loss-of-function mutations were enriched in gastric and colorectal cancers. Deletion of Nalcn from gastric, intestinal or pancreatic adenocarcinomas in mice did not alter tumor incidence, but markedly increased the number of circulating tumor cells (CTCs) and metastases. Treatment of these mice with gadolinium-a NALCN channel blocker-similarly increased CTCs and metastases. Deletion of Nalcn from mice that lacked oncogenic mutations and never developed cancer caused shedding of epithelial cells into the blood at levels equivalent to those seen in tumor-bearing animals. These cells trafficked to distant organs to form normal structures including lung epithelium, and kidney glomeruli and tubules. Thus, NALCN regulates cell shedding from solid tissues independent of cancer, divorcing this process from tumorigenesis and unmasking a potential new target for antimetastatic therapies.
Assuntos
Neoplasias , Humanos , Camundongos , Animais , Canais Iônicos/genética , Proteínas de Membrana/genéticaRESUMO
BACKGROUND & AIMS: Indian Hedgehog (Ihh) is expressed by the differentiated epithelial cells of the small intestine and signals to the mesenchyme where it induces unidentified factors that negatively regulate intestinal epithelial precursor cell fate. Recently, genetic variants in the Hh pathway have been linked to the development of inflammatory bowel disease. METHODS: We deleted Ihh from the small intestinal epithelium in adult mice using Cyp1a1-CreIhh(fl/fl) conditional Ihh mutant mice. Intestines were examined by immunohistochemistry, in situ hybridization, and real-time polymerase chain reaction. RESULTS: Deletion of Ihh from the intestinal epithelium initially resulted in a proliferative response of the intestinal epithelium with lengthening and fissioning of crypts and increased Wnt signaling. The epithelial proliferative response was associated with loss of bone morphogenetic protein and Activin signaling from the epithelium of the villus and crypts, respectively. At the same stage we observed a substantial influx of fibroblasts and macrophages into the villus core with increased mesenchymal transforming growth factor-ß signaling and deposition of extracellular matrix proteins. Prolonged loss of Ihh resulted in progressive leukocyte infiltration of the crypt area, blunting and loss of villi, and the development of intestinal fibrosis. CONCLUSIONS: Loss of Ihh initiates several events that are characteristic of an intestinal wound repair response. Prolonged loss resulted in progressive inflammation, mucosal damage, and the development of intestinal fibrosis. Ihh is a signal derived from the superficial epithelial cells that may act as a critical indicator of epithelial integrity.
Assuntos
Proteínas Hedgehog/genética , Doenças Inflamatórias Intestinais/genética , Mucosa Intestinal/patologia , Intestino Delgado/patologia , Cicatrização/genética , Animais , Proliferação de Células , Modelos Animais de Doenças , Progressão da Doença , Proteínas Hedgehog/biossíntese , Imuno-Histoquímica , Hibridização In Situ , Doenças Inflamatórias Intestinais/metabolismo , Doenças Inflamatórias Intestinais/patologia , Mucosa Intestinal/metabolismo , Intestino Delgado/lesões , Intestino Delgado/metabolismo , Camundongos , Camundongos Mutantes , Reação em Cadeia da Polimerase , Transdução de Sinais , Fator de Crescimento Transformador beta/metabolismoRESUMO
BACKGROUND: Reporter genes are widely used in biology and only a limited number are available. We present a new reporter gene for the localization of mammalian cells and transgenic tissues based on detection of the bglA (SYNbglA) gene of Caldocellum saccharolyticum that encodes a thermophilic beta-glucosidase. RESULTS: SYNbglA was generated by introducing codon substitutions to remove CpG motifs as these are associated with gene silencing in mammalian cells. SYNbglA expression can be localized in situ or detected quantitatively in colorimetric assays and can be co-localized with E. coli beta-galactosidase. Further, we have generated a Cre-reporter mouse in which SYNbglA is expressed following recombination to demonstrate the general utility of SYNbglA for in vivo analyses. SYNbglA can be detected in tissue wholemounts and in frozen and wax embedded sections. CONCLUSIONS: SYNbglA will have general applicability to developmental and molecular studies in vitro and in vivo.
Assuntos
Genes Reporter , Thermoanaerobacter/enzimologia , beta-Galactosidase/genética , Animais , Linhagem Celular , Estabilidade Enzimática , Expressão Gênica , Temperatura Alta , Humanos , Camundongos , Camundongos Transgênicos , Células NIH 3T3 , beta-Galactosidase/análiseRESUMO
The tissue dynamics that govern maintenance and regeneration of the pancreas remain largely unknown. In particular, the presence and nature of a cellular hierarchy remains a topic of debate. Previous lineage tracing strategies in the pancreas relied on specific marker genes for clonal labeling, which left other populations untested and failed to account for potential widespread phenotypical plasticity. Here we employed a tracing system that depends on replication-induced clonal marks. We found that, in homeostasis, steady acinar replacement events characterize tissue dynamics, to which all acinar cells have an equal ability to contribute. Similarly, regeneration following pancreatitis was best characterized by an acinar self-replication model because no evidence of a cellular hierarchy was detected. In particular, rapid regeneration in the pancreas was found to be driven by an accelerated rate of acinar fission-like events. These results provide a comprehensive and quantitative model of cell dynamics in the exocrine pancreas.
Assuntos
Pâncreas Exócrino , Pancreatite , Células Acinares , Homeostase , Humanos , PâncreasRESUMO
Cytosine hydroxymethylation (5hmC) in mammalian DNA is the product of oxidation of methylated cytosines (5mC) by Ten-Eleven-Translocation (TET) enzymes. While it has been shown that the TETs influence 5mC metabolism, pluripotency and differentiation during early embryonic development, the functional relationship between gene expression and 5hmC in adult (somatic) stem cell differentiation is still unknown. Here we report that 5hmC levels undergo highly dynamic changes during adult stem cell differentiation from intestinal progenitors to differentiated intestinal epithelium. We profiled 5hmC and gene activity in purified mouse intestinal progenitors and differentiated progeny to identify 43425 differentially hydroxymethylated regions and 5325 differentially expressed genes. These differentially marked regions showed both losses and gains of 5hmC after differentiation, despite lower global levels of 5hmC in progenitor cells. In progenitors, 5hmC did not correlate with gene transcript levels, however, upon differentiation the global increase in 5hmC content showed an overall positive correlation with gene expression level as well as prominent associations with histone modifications that typify active genes and enhancer elements. Our data support a gene regulatory role for 5hmC that is predominant over its role in controlling DNA methylation states.
Assuntos
5-Metilcitosina/análogos & derivados , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/genética , Intestinos/citologia , 5-Metilcitosina/farmacologia , Células-Tronco Adultas/citologia , Células-Tronco Adultas/efeitos dos fármacos , Animais , CamundongosRESUMO
Summary K-ras mutations are found in 40-50% of human colorectal adenomas and carcinomas, but their functional contribution remains incompletely understood. Here, we show that a conditional mutant K-ras mouse model (K-ras(Asp12)/Cre), with transient intestinal Cre activation by beta-Naphthoflavone (beta-NF) treatment, displayed transgene recombination and K-ras(Asp12) expression in the murine intestines, but developed few intestinal adenomas over 2 years. However, when crossed with Apc(Min/+) mice, the K-ras(Asp12)/Cre/Apc(Min/+) offspring showed acceleration of intestinal tumourigenesis with significantly changed average lifespan (P < 0.05) decreased to 18.4 +/- 5.4 weeks from 20.9 +/- 4.7 weeks (control Apc(Min/+) mice). The numbers of adenomas in the small intestine and large intestine were significantly (P < 0.01) increased by 1.5-fold and 5.7-fold, respectively, in K-ras(Asp12)/Cre/Apc(Min/+) mice compared with Apc(Min/+) mice, with the more marked increase in adenoma prevalence in the large intestine. To explore possible mechanisms for K-ras(Asp12) and Apc(Min) co-operation, the Mitogen-activated protein kinase (Mapk), Akt and Wnt signalling pathways, including selected target gene expression levels, were evaluated in normal large intestine and large intestinal tumours. K-ras(Asp12) increased activation of Mapk and Akt signalling pathway targets phospho-extracellular signal-regulated kinase (pErk) and pAkt, and increased relative expression levels of Wnt pathway targets vascular endothelial growth factor (VEGF), gastrin, cyclo-oxygenase 2 (Cox2) and T-cell lymphoma invasion and metastasis 1 (Tiam1) in K-ras(Asp12)/Cre/Apc(Min/+) adenomas compared with that of Apc(Min/+) adenomas, although other Wnt signalling pathway target genes such as Peroxisome proliferator-activated receptor delta (PPARd), matrix metalloproteinase 7 (MMP7), protein phosphatase 1 alpha (PP1A) and c-myc remained unchanged. In conclusion, intestinal expression of K-ras(Asp12) promotes mutant Apc-initiated intestinal adenoma formation in vivo more in the large intestine than the small intestine, with evidence of synergistic co-operation between mutant K-ras and Apc involving increased expression of some Wnt-pathway target genes.
Assuntos
Adenoma/genética , Transformação Celular Neoplásica/genética , Genes ras/genética , Neoplasias Intestinais/genética , Intestino Grosso/metabolismo , Intestino Delgado/metabolismo , Adenoma/metabolismo , Proteína da Polipose Adenomatosa do Colo/genética , Proteína da Polipose Adenomatosa do Colo/metabolismo , Animais , Sequência de Bases , Transformação Celular Neoplásica/metabolismo , DNA de Neoplasias/genética , Regulação Neoplásica da Expressão Gênica , Genótipo , Neoplasias Intestinais/metabolismo , Neoplasias Intestinais/patologia , Camundongos , Camundongos Transgênicos , Dados de Sequência Molecular , Mutação , Proteínas de Neoplasias/metabolismo , Proteínas de Neoplasias/fisiologia , Proteína Oncogênica p21(ras)/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/fisiologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Transdução de Sinais/fisiologia , Proteínas Wnt/fisiologiaRESUMO
Bcl9 and Pygo are Wnt enhanceosome components that effect ß-catenin-dependent transcription. Whether they mediate ß-catenin-dependent neoplasia is unclear. Here we assess their roles in intestinal tumourigenesis initiated by Apc loss-of-function (ApcMin), or by Apc1322T encoding a partially-functional Apc truncation commonly found in colorectal carcinomas. Intestinal deletion of Bcl9 extends disease-free survival in both models, and essentially cures Apc1322T mice of their neoplasia. Loss-of-Bcl9 synergises with loss-of-Pygo to shift gene expression within Apc-mutant adenomas from stem cell-like to differentiation along Notch-regulated secretory lineages. Bcl9 loss also promotes tumour retention in ApcMin mice, apparently via relocating nuclear ß-catenin to the cell surface, but this undesirable effect is not seen in Apc1322T mice whose Apc truncation retains partial function in regulating ß-catenin. Our results demonstrate a key role of the Wnt enhanceosome in ß-catenin-dependent intestinal tumourigenesis and reveal the potential of BCL9 as a therapeutic target during early stages of colorectal cancer.
Assuntos
Proteína da Polipose Adenomatosa do Colo/metabolismo , Carcinogênese , Mucosa Intestinal/metabolismo , Neoplasias Intestinais/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Adenoma , Proteína da Polipose Adenomatosa do Colo/genética , Animais , Transformação Celular Neoplásica , Neoplasias Colorretais , Modelos Animais de Doenças , Regulação Neoplásica da Expressão Gênica , Genes APC , Intestinos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fatores de Transcrição , Via de Sinalização Wnt , beta Catenina/metabolismoRESUMO
Microsatellite sequences have an enhanced susceptibility to mutation, and can act as sentinels indicating elevated mutation rates and increased risk of cancer. The probability of mutant fixation within the intestinal epithelium is dictated by a combination of stem cell dynamics and mutation rate. Here, we exploit this relationship to infer microsatellite mutation rates. First a sensitive, multiplexed, and quantitative method for detecting somatic changes in microsatellite length was developed that allowed the parallel detection of mutant [CA]n sequences from hundreds of low-input tissue samples at up to 14 loci. The method was applied to colonic crypts in Mus musculus, and enabled detection of mutant subclones down to 20% of the cellularity of the crypt (â¼50 of 250 cells). By quantifying age-related increases in clone frequencies for multiple loci, microsatellite mutation rates in wild-type and Msh2-deficient epithelium were established. An average 388-fold increase in mutation per mitosis rate was observed in Msh2-deficient epithelium (2.4 × 10-2) compared to wild-type epithelium (6.2 × 10-5).
Assuntos
Células-Tronco Adultas/metabolismo , Mucosa Intestinal/citologia , Repetições de Microssatélites , Proteína 2 Homóloga a MutS/genética , Taxa de Mutação , Células-Tronco Adultas/citologia , Animais , Feminino , Mucosa Intestinal/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mitose , Proteína 2 Homóloga a MutS/deficiênciaRESUMO
[This corrects the article DOI: 10.1371/journal.pone.0004264.].
RESUMO
In this issue of JEM, Balbinot et al. (https://doi.org/10.1084/jem.20170934) describe an original mechanism where Cdx2 inactivation regulates intestinal metaplastic to neoplastic transition in a paracrine fashion. Surprisingly, the target cells are neighboring "normal" Cdx2-positive cells.