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1.
Cell ; 163(5): 1237-1251, 2015 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-26590425

RESUMO

K-Ras and H-Ras share identical effectors and have similar properties; however, the high degree of tumor-type specificity associated with K-Ras and H-Ras mutations suggests that they have unique roles in oncogenesis. Here, we report that oncogenic K-Ras, but not H-Ras, suppresses non-canonical Wnt/Ca(2+) signaling, an effect that contributes strongly to its tumorigenic properties. K-Ras does this by binding to calmodulin and so reducing CaMKii activity and expression of Fzd8. Restoring Fzd8 in K-Ras mutant pancreatic cells suppresses malignancy, whereas depletion of Fzd8 in H-Ras(V12)-transformed cells enhances their tumor initiating capacity. Interrupting K-Ras-calmodulin binding using genetic means or by treatment with an orally active protein kinase C (PKC)-activator, prostratin, represses tumorigenesis in K-Ras mutant pancreatic cancer cells. These findings provide an alternative way to selectively target this "undruggable" protein.


Assuntos
Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Receptores de Superfície Celular/metabolismo , Via de Sinalização Wnt , Sequência de Aminoácidos , Animais , Animais Geneticamente Modificados , Calmodulina/metabolismo , Linhagem Celular Tumoral , Modelos Animais de Doenças , Feminino , Genes ras , Humanos , Camundongos , Dados de Sequência Molecular , Neoplasias Pancreáticas/tratamento farmacológico , Neoplasias Pancreáticas/metabolismo , Papiloma/metabolismo , Ésteres de Forbol/administração & dosagem , Fosforilação , Ligação Proteica/efeitos dos fármacos
2.
Nature ; 517(7535): 489-92, 2015 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-25363767

RESUMO

Next-generation sequencing of human tumours has refined our understanding of the mutational processes operative in cancer initiation and progression, yet major questions remain regarding the factors that induce driver mutations and the processes that shape mutation selection during tumorigenesis. Here we performed whole-exome sequencing on adenomas from three mouse models of non-small-cell lung cancer, which were induced either by exposure to carcinogens (methyl-nitrosourea (MNU) and urethane) or by genetic activation of Kras (Kras(LA2)). Although the MNU-induced tumours carried exactly the same initiating mutation in Kras as seen in the Kras(LA2) model (G12D), MNU tumours had an average of 192 non-synonymous, somatic single-nucleotide variants, compared with only six in tumours from the Kras(LA2) model. By contrast, the Kras(LA2) tumours exhibited a significantly higher level of aneuploidy and copy number alterations compared with the carcinogen-induced tumours, suggesting that carcinogen-induced and genetically engineered models lead to tumour development through different routes. The wild-type allele of Kras has been shown to act as a tumour suppressor in mouse models of non-small-cell lung cancer. We demonstrate that urethane-induced tumours from wild-type mice carry mostly (94%) Kras Q61R mutations, whereas those from Kras heterozygous animals carry mostly (92%) Kras Q61L mutations, indicating a major role for germline Kras status in mutation selection during initiation. The exome-wide mutation spectra in carcinogen-induced tumours overwhelmingly display signatures of the initiating carcinogen, while adenocarcinomas acquire additional C > T mutations at CpG sites. These data provide a basis for understanding results from human tumour genome sequencing, which has identified two broad categories of tumours based on the relative frequency of single-nucleotide variations and copy number alterations, and underline the importance of carcinogen models for understanding the complex mutation spectra seen in human cancers.


Assuntos
Transformação Celular Neoplásica/induzido quimicamente , Transformação Celular Neoplásica/genética , Genes ras/genética , Neoplasias Pulmonares/induzido quimicamente , Neoplasias Pulmonares/genética , Mutação/genética , Proteína Oncogênica p21(ras)/genética , Proteínas Proto-Oncogênicas p21(ras)/genética , Adenocarcinoma/induzido quimicamente , Adenocarcinoma/genética , Animais , Carcinógenos/toxicidade , Carcinoma Pulmonar de Células não Pequenas/induzido quimicamente , Carcinoma Pulmonar de Células não Pequenas/genética , Variações do Número de Cópias de DNA/genética , Progressão da Doença , Feminino , Instabilidade Genômica/genética , Mutação em Linhagem Germinativa/genética , Humanos , Masculino , Metilnitrosoureia/toxicidade , Camundongos , Modelos Genéticos , Mutação Puntual/genética , Uretana/toxicidade
3.
Proc Natl Acad Sci U S A ; 111(20): 7373-8, 2014 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-24785298

RESUMO

Homeodomain-interacting protein kinase 2 (Hipk2) has previously been implicated in the control of several transcription factors involved in embryonic development, apoptosis, cell proliferation, and tumor development, but very little is understood about the exact mechanisms through which Hipk2 influences these processes. Analysis of gene expression in normal tissues from genetically heterogeneous mouse or human populations can reveal network motifs associated with the structural or functional components of the tissue, and may predict roles for genes of unknown function. Here we have applied this network strategy to uncover a role for the Hipk2 gene in the transcriptional system controlling adipogenesis. Both in vitro and in vivo models were used to show that knockdown or loss of Hipk2 specifically inhibits white adipose cell differentiation and tissue development. In addition, loss of Hipk2 leads to induction of pockets of multilocular brown fat-like cells in remaining white adipose depots, which express markers of brown and beige fat such as uncoupling protein 1 and transmembrane protein 26. These changes are accompanied by increased insulin sensitivity in Hipk2 knockout mice and reduced high-fat diet-induced weight gain, highlighting a potential role for this kinase in diseases such as diabetes and obesity. Our study underscores the versatility and power of a readily available tissue, such as skin, for network modeling of systemic transcriptional programs involved in multiple pathways, including lipid metabolism and adipogenesis.


Assuntos
Adipogenia , Tecido Adiposo Branco/fisiologia , Proteínas de Transporte/fisiologia , Regulação da Expressão Gênica , Proteínas Serina-Treonina Quinases/fisiologia , Células 3T3-L1 , Adipócitos/citologia , Tecido Adiposo Marrom/citologia , Animais , Proteínas Reguladoras de Apoptose/metabolismo , Proteínas de Transporte/genética , Diferenciação Celular , Fragmentação do DNA , Dieta Hiperlipídica , Feminino , Insulina/metabolismo , Masculino , Glândulas Mamárias Animais/metabolismo , Camundongos , Camundongos Knockout , Obesidade/genética , PPAR gama/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Proteínas Serina-Treonina Quinases/genética , Fatores de Transcrição/metabolismo
4.
Science ; 384(6699): eadi7453, 2024 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-38815020

RESUMO

Stem cells play a critical role in cancer development by contributing to cell heterogeneity, lineage plasticity, and drug resistance. We created gene expression networks from hundreds of mouse tissue samples (both normal and tumor) and integrated these with lineage tracing and single-cell RNA-seq, to identify convergence of cell states in premalignant tumor cells expressing markers of lineage plasticity and drug resistance. Two of these cell states representing multilineage plasticity or proliferation were inversely correlated, suggesting a mutually exclusive relationship. Treatment of carcinomas in vivo with chemotherapy repressed the proliferative state and activated multilineage plasticity whereas inhibition of differentiation repressed plasticity and potentiated responses to cell cycle inhibitors. Manipulation of this cell state transition point may provide a source of potential combinatorial targets for cancer therapy.


Assuntos
Carcinoma de Células Escamosas , Linhagem da Célula , Células-Tronco Neoplásicas , Neoplasias Cutâneas , Animais , Camundongos , Neoplasias Cutâneas/patologia , Neoplasias Cutâneas/genética , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Células-Tronco Neoplásicas/patologia , Análise de Célula Única , Diferenciação Celular , Resistencia a Medicamentos Antineoplásicos/genética , Plasticidade Celular , Proliferação de Células , Redes Reguladoras de Genes , RNA-Seq , Regulação Neoplásica da Expressão Gênica
5.
bioRxiv ; 2023 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-37215032

RESUMO

Adult mammalian stem cells play critical roles in normal tissue homeostasis, as well as in tumor development, by contributing to cell heterogeneity, plasticity, and development of drug resistance. The relationship between different types of normal and cancer stem cells is highly controversial and poorly understood. Here, we carried out gene expression network analysis of normal and tumor samples from genetically heterogeneous mice to create network metagenes for visualization of stem-cell networks, rather than individual stem-cell markers, at the single-cell level during multistage carcinogenesis. We combined this approach with lineage tracing and single-cell RNASeq of stem cells and their progeny, identifying a previously unrecognized hierarchy in which Lgr6+ stem cells from tumors generate progeny that express a range of other stem-cell markers including Sox2, Pitx1, Foxa1, Klf5, and Cd44. Our data identify a convergence of multiple stem-cell and tumor-suppressor pathways in benign tumor cells expressing markers of lineage plasticity and oxidative stress. This same single-cell population expresses network metagenes corresponding to markers of cancer drug resistance in human tumors of the skin, lung and prostate. Treatment of mouse squamous carcinomas in vivo with the chemotherapeutic cis-platin resulted in elevated expression of the genes that mark this cell population. Our data have allowed us to create a simplified model of multistage carcinogenesis that identifies distinct stem-cell states at different stages of tumor progression, thereby identifying networks involved in lineage plasticity, drug resistance, and immune surveillance, providing a rich source of potential targets for cancer therapy.

6.
Nat Commun ; 12(1): 4288, 2021 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-34257283

RESUMO

The commonly mutated human KRAS oncogene encodes two distinct KRAS4A and KRAS4B proteins generated by differential splicing. We demonstrate here that coordinated regulation of both isoforms through control of splicing is essential for development of Kras mutant tumors. The minor KRAS4A isoform is enriched in cancer stem-like cells, where it responds to hypoxia, while the major KRAS4B is induced by ER stress. KRAS4A splicing is controlled by the DCAF15/RBM39 pathway, and deletion of KRAS4A or pharmacological inhibition of RBM39 using Indisulam leads to inhibition of cancer stem cells. Our data identify existing clinical drugs that target KRAS4A splicing, and suggest that levels of the minor KRAS4A isoform in human tumors can be a biomarker of sensitivity to some existing cancer therapeutics.


Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Células-Tronco Neoplásicas/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Proteínas de Ligação a RNA/metabolismo , Células A549 , Animais , Western Blotting , Proliferação de Células , Citometria de Fluxo , Xenoenxertos , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Camundongos , Camundongos Knockout , Reação em Cadeia da Polimerase , Proteínas Proto-Oncogênicas p21(ras)/genética , Proteínas de Ligação a RNA/genética
7.
Nature ; 432(7018): 775-9, 2004 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-15592418

RESUMO

The FBXW7/hCDC4 gene encodes a ubiquitin ligase implicated in the control of chromosome stability. Here we identify the mouse Fbxw7 gene as a p53-dependent tumour suppressor gene by using a mammalian genetic screen for p53-dependent genes involved in tumorigenesis. Radiation-induced lymphomas from p53+/- mice, but not those from p53-/- mice, show frequent loss of heterozygosity and a 10% mutation rate of the Fbxw7 gene. Fbxw7+/- mice have greater susceptibility to radiation-induced tumorigenesis, but most tumours retain and express the wild-type allele, indicating that Fbxw7 is a haploinsufficient tumour suppressor gene. Loss of Fbxw7 alters the spectrum of tumours that develop in p53 deficient mice to include a range of tumours in epithelial tissues such as the lung, liver and ovary. Mouse embryo fibroblasts from Fbxw7-deficient mice, or wild-type mouse cells expressing Fbxw7 small interfering RNA, have higher levels of Aurora-A kinase, c-Jun and Notch4, but not of cyclin E. We propose that p53-dependent loss of Fbxw7 leads to genetic instability by mechanisms that might involve the activation of Aurora-A, providing a rationale for the early occurrence of these mutations in human cancers.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Proteínas F-Box/metabolismo , Genes Supressores de Tumor/fisiologia , Proteína Supressora de Tumor p53/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Animais , Sequência de Bases , Proteínas de Ciclo Celular/genética , Transformação Celular Neoplásica/patologia , Transformação Celular Neoplásica/efeitos da radiação , Proteínas F-Box/genética , Proteína 7 com Repetições F-Box-WD , Feminino , Fibroblastos , Deleção de Genes , Perda de Heterozigosidade/genética , Masculino , Camundongos , Camundongos Knockout , Mutação/genética , Neoplasias/patologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Taxa de Sobrevida , Proteína Supressora de Tumor p53/deficiência , Proteína Supressora de Tumor p53/genética , Ubiquitina-Proteína Ligases/deficiência , Ubiquitina-Proteína Ligases/genética
8.
Nat Genet ; 49(11): 1624-1632, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28945253

RESUMO

The G-protein-coupled receptors LGR4, LGR5 and LGR6 are Wnt signaling mediators, but their functions in squamous cell carcinoma (SCC) are unclear. Using lineage tracing in Lgr5-EGFP-CreERT2/Rosa26-Tomato and Lgr6-EGFP-CreERT2/Rosa26-Tomato reporter mice, we demonstrate that Lgr6, but not Lgr5, acts as an epithelial stem cell marker in SCCs in vivo. We identify, by single-molecule in situ hybridization and cell sorting, rare cells positive for Lgr6 expression in immortalized keratinocytes and show that their frequency increases in advanced SCCs. Lgr6 expression is enriched in cells with stem cell characteristics, and Lgr6 downregulation in vivo causes increased epidermal proliferation with expanded lineage tracing from epidermal stem cells positive for Lgr6 expression. Surprisingly, mice with germline knockout of Lgr6 are predisposed to SCC development, through a mechanism that includes compensatory upregulation of Lgr5. These data provide a model for human patients with germline loss-of-function mutations in Wnt pathway genes, including RSPO1 or LGR4, who show increased susceptibility to squamous tumor development.


Assuntos
Carcinoma de Células Escamosas/genética , Regulação Neoplásica da Expressão Gênica , Queratinócitos/metabolismo , Células-Tronco Neoplásicas/metabolismo , Receptores Acoplados a Proteínas G/genética , Neoplasias Cutâneas/genética , Animais , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/patologia , Linhagem Celular Transformada , Epiderme/metabolismo , Epiderme/patologia , Humanos , Queratinócitos/patologia , Camundongos , Camundongos Transgênicos , Células-Tronco Neoplásicas/patologia , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Receptores Acoplados a Proteínas G/antagonistas & inibidores , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais , Neoplasias Cutâneas/metabolismo , Neoplasias Cutâneas/patologia , Trombospondinas/genética , Trombospondinas/metabolismo
9.
Oncogene ; 24(35): 5521-4, 2005 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-16007185

RESUMO

p53 is one of the most important tumor suppressor genes in human cancer, but the roles of its homologues p63 and p73 in tumor suppression, alone or in collaboration with p53, remains controversial. Both p63 and p73 can be deregulated after DNA damage, and induce cell cycle arrest and apoptosis, but mice carrying inactive alleles of these genes do not develop spontaneous tumors. Since heterozygous loss of p53 confers strong sensitization to radiation-induced lymphoma development, we investigated the possibility that radiation exposure may reveal previously undetected tumor suppressor properties in p63 or p73, alone or in combination with p53. Animals heterozygous for p63 or p73, as well as both double heterozygous p53/p63 or p53/p73 mice, showed no significant differences in tumor latency, spectrum or frequency after gamma-radiation, compared to their control counterparts. Deletions were found near the p63 locus on chromosome 16 in radiation-induced tumors, but these frequently included the knockout allele. No deletions or LOH involving the p73 gene were detected, and expression of both genes was maintained in the tumors. We conclude that p53 homologues do not contribute to p53 tumor suppressor activity in lymphoma development.


Assuntos
Proteínas de Ligação a DNA/genética , Linfoma/genética , Neoplasias Induzidas por Radiação/genética , Proteínas Nucleares/genética , Fosfoproteínas/genética , Transativadores/genética , Proteína Supressora de Tumor p53/genética , Animais , Sequência de Bases , Genes Supressores de Tumor , Perda de Heterozigosidade , Camundongos , Camundongos Knockout , Dados de Sequência Molecular , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína Tumoral p73 , Proteínas Supressoras de Tumor
10.
Oncogene ; 24(53): 7924-34, 2005 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-16116484

RESUMO

Although radiation can directly induce DNA damage and is a known human and animal carcinogen, the number of genetic changes in radiation-induced tumors, and the pathways responsible for generating them, are unknown. We have used high-density BAC arrays covering >95% of the mouse genome for analysis of genomic patterns of aberrations in spontaneous and radiation-induced mouse lymphomas. The majority of radiation-induced tumors exhibit one of three 'signatures' based on gene copy number changes. Some exhibit extensive scrambling of the genome, with very high numbers of recurrent gains and losses. Two other signatures are characterized by excess gains but relatively few losses, or vice versa. Changes in spontaneous tumors often involve whole chromosomes, whereas radiation-induced tumors exhibit a high frequency of localized deletion/amplification events. The number of copy number abnormalities does not correlate with the latency or pathology of the tumors. We propose that specific early events following radiation exposure induce changes in 'caretaker' genes that control specific downstream pathways involved in DNA damage repair. The nature of these early events may determine the overall genomic signature observed in the resulting tumor.


Assuntos
Dano ao DNA/efeitos da radiação , Genes p53 , Instabilidade Genômica/efeitos da radiação , Linfoma/etiologia , Linfoma/genética , Neoplasias Induzidas por Radiação/genética , Neoplasias do Timo/genética , Animais , Reparo do DNA , Feminino , Amplificação de Genes , Deleção de Genes , Perfilação da Expressão Gênica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neoplasias do Timo/etiologia
11.
Cell Rep ; 16(4): 1153-1165, 2016 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-27425619

RESUMO

Inherited germline polymorphisms can cause gene expression levels in normal tissues to differ substantially between individuals. We present an analysis of the genetic architecture of normal adult skin from 470 genetically unique mice, demonstrating the effect of germline variants, skin tissue location, and perturbation by exogenous inflammation or tumorigenesis on gene signaling pathways. Gene networks related to specific cell types and signaling pathways, including sonic hedgehog (Shh), Wnt, Lgr family stem cell markers, and keratins, differed at these tissue sites, suggesting mechanisms for the differential susceptibility of dorsal and tail skin to development of skin diseases and tumorigenesis. The Pten tumor suppressor gene network is rewired in premalignant tumors compared to normal tissue, but this response to perturbation is lost during malignant progression. We present a software package for expression quantitative trait loci (eQTL) network analysis and demonstrate how network analysis of whole tissues provides insights into interactions between cell compartments and signaling molecules.


Assuntos
Carcinogênese/genética , Expressão Gênica/genética , Inflamação/genética , Inflamação/patologia , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/patologia , Pele/patologia , Animais , Carcinogênese/patologia , Progressão da Doença , Redes Reguladoras de Genes/genética , Predisposição Genética para Doença/genética , Células Germinativas/fisiologia , Camundongos , Polimorfismo Genético/genética , Locos de Características Quantitativas/genética , Transdução de Sinais/genética
12.
Oncogene ; 22(52): 8379-85, 2003 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-14627978

RESUMO

Genetic analysis of radiation-induced lymphomas from p53 heterozygous or null mice has revealed a high frequency of genetic alterations on mouse chromosome 19. Detailed microsatellite analysis of chromosome 19 deletions identified three independent regions of loss of heterozygosity, one of which was refined to a 0.3 Mb interval that contained the Pten tumor suppressor gene. More than 50% of radiation-induced tumors from p53+/- and p53-/- mice showed heterozygous loss of one Pten allele. In most cases, the remaining allele was wild type and expressed, suggesting that Pten is a haploinsufficient tumor suppressor gene for mouse lymphoma development. This conclusion was supported by the detection of specific intragenic deletions in Pten in tumors that retained one wild-type allele. Pten heterozygous mice were just as sensitive as p53+/- mice to induction of tumors by radiation, and surprisingly, the double p53+/-Pten+/-mice were equivalent to p53 null mice in radiation sensitivity. Despite the fact that Pten appears to be a haploinsufficient tumor suppressor gene, most tumors from both the single and double heterozygous mice had lost the remaining wild-type allele. The mechanism of loss in all cases involved the complete chromosome, suggesting that it is driven by other tumor suppressor genes on this chromosome. This sensitized screen therefore identified complementary roles for Pten and p53 pathways in suppression of tumor development induced by radiation exposure.


Assuntos
Linfoma/metabolismo , Neoplasias Induzidas por Radiação/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Animais , Western Blotting , Perda de Heterozigosidade , Linfoma/etiologia , Linfoma/genética , Camundongos , Neoplasias Induzidas por Radiação/etiologia , Neoplasias Induzidas por Radiação/genética , PTEN Fosfo-Hidrolase , Monoéster Fosfórico Hidrolases/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de Tempo , Proteína Supressora de Tumor p53/genética , Proteínas Supressoras de Tumor/genética
13.
Nat Med ; 21(12): 1514-20, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26523969

RESUMO

Human tumors show a high level of genetic heterogeneity, but the processes that influence the timing and route of metastatic dissemination of the subclones are unknown. Here we have used whole-exome sequencing of 103 matched benign, malignant and metastatic skin tumors from genetically heterogeneous mice to demonstrate that most metastases disseminate synchronously from the primary tumor, supporting parallel rather than linear evolution as the predominant model of metastasis. Shared mutations between primary carcinomas and their matched metastases have the distinct A-to-T signature of the initiating carcinogen dimethylbenzanthracene, but non-shared mutations are primarily G-to-T, a signature associated with oxidative stress. The existence of carcinomas that either did or did not metastasize in the same host animal suggests that there are tumor-intrinsic factors that influence metastatic seeding. We also demonstrate the importance of germline polymorphisms in determining allele-specific mutations, and we identify somatic genetic alterations that are specifically related to initiation of carcinogenesis by Hras or Kras mutations. Mouse tumors that mimic the genetic heterogeneity of human cancers can aid our understanding of the clonal evolution of metastasis and provide a realistic model for the testing of novel therapies.


Assuntos
Evolução Clonal , Mutação/genética , Neoplasias Cutâneas/induzido quimicamente , Neoplasias Cutâneas/secundário , 9,10-Dimetil-1,2-benzantraceno , Animais , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Cruzamentos Genéticos , Variações do Número de Cópias de DNA/genética , Progressão da Doença , Transição Epitelial-Mesenquimal , Feminino , Humanos , Masculino , Camundongos , Filogenia , Neoplasias Cutâneas/genética , Proteínas ras/genética
14.
PLoS One ; 7(2): e31301, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22348067

RESUMO

Genome-wide association studies (GWAS) have been successful in finding associations between specific genetic variants and cancer susceptibility in human populations. These studies have identified a range of highly statistically significant associations between single nucleotide polymorphisms (SNPs) and susceptibility to development of a range of human tumors. However, the effect of each SNP in isolation is very small, and all of the SNPs combined only account for a relatively minor proportion of the total genetic risk (5-10%). There is therefore a major requirement for alternative routes to the discovery of genetic risk factors for cancer. We have previously shown using mouse models that chromosomal regions harboring susceptibility genes identified by linkage analysis frequently exhibit allele-specific genetic alterations in tumors. We demonstrate here that the Fbxw7 gene, a commonly mutated gene in a wide range of mouse and human cancers, shows allele-specific deletions in mouse lymphomas and skin tumors. Lymphomas from three different F1 hybrids show 100% allele-specificity in the patterns of allelic loss. Parental alleles from 129/Sv or Spretus/Gla mice are lost in tumors from F1 hybrids with C57BL/6 animals, due to the presence of a specific non-synonymous coding sequence polymorphism at the N-terminal portion of the gene. A specific genetic test of association between this SNP and lymphoma susceptibility in interspecific backcross mice showed a significant linkage (p = 0.001), but only in animals with a functional p53 gene. These data therefore identify Fbxw7 as a p53-dependent tumor susceptibility gene. Increased p53-dependent tumor susceptibility and allele-specific losses were also seen in a mouse skin model of skin tumor development. We propose that analysis of preferential allelic imbalances in tumors may provide an efficient means of uncovering genetic variants that affect mouse and human tumor susceptibility.


Assuntos
Proteínas F-Box/genética , Predisposição Genética para Doença , Neoplasias/genética , Ubiquitina-Proteína Ligases/genética , Alelos , Animais , Proteína 7 com Repetições F-Box-WD , Estudo de Associação Genômica Ampla , Mutação em Linhagem Germinativa , Linfoma/genética , Camundongos , Deleção de Sequência , Neoplasias Cutâneas/genética , Proteína Supressora de Tumor p53
15.
Mol Cancer Res ; 10(6): 834-44, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22513362

RESUMO

The Aurora-A kinase gene is frequently amplified and/or overexpressed in a variety of human cancers, leading to major efforts to develop therapeutic agents targeting this pathway. Here, we show that Aurora-A is targeted for ubiquitination and subsequent degradation by the F-box protein FBXW7 in a process that is regulated by GSK3ß. Using a series of truncated Aurora-A proteins and site-directed mutagenesis, we identified distinct FBXW7 and GSK3ß-binding sites in Aurora-A. Mutation of critical residues in either site substantially disrupts degradation of Aurora-A. Furthermore, we show that loss of Pten results in the stabilization of Aurora-A by attenuating FBXW7-dependent degradation of Aurora-A through the AKT/GSK3ß pathway. Moreover, radiation-induced tumor latency is significantly shortened in Fbxw7(+/-)Pten(+/-) mice as compared with either Fbxw7(+/-) or Pten(+/-) mice, indicating that Fbxw7 and Pten appear to cooperate in suppressing tumorigenesis. Our results establish a novel posttranslational regulatory network in which the Pten and Fbxw7 pathways appear to converge on the regulation of Aurora-A level.


Assuntos
Proteínas F-Box/metabolismo , Neoplasias Induzidas por Radiação/metabolismo , PTEN Fosfo-Hidrolase/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Animais , Aurora Quinase A , Aurora Quinases , Sítios de Ligação/genética , Western Blotting , Linhagem Celular , Proteínas F-Box/genética , Proteína 7 com Repetições F-Box-WD , Feminino , Raios gama , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Células HCT116 , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mutação , Células NIH 3T3 , Neoplasias Induzidas por Radiação/genética , Neoplasias Induzidas por Radiação/patologia , PTEN Fosfo-Hidrolase/genética , Ligação Proteica , Proteínas Serina-Treonina Quinases/genética , Fatores de Tempo , Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/genética
16.
J Clin Oncol ; 28(23): 3770-8, 2010 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-20625127

RESUMO

PURPOSE: To investigate the role of the PER3 circadian rhythm gene, located within the commonly deleted region of chromosome 1p36, in human breast cancer development. PATIENTS AND METHODS: The frequency of genetic alterations at 1p36 and PER3 gene copy number status were analyzed in 180 lymph node-negative breast cancers from patients who had received treatment with chemotherapy and/or tamoxifen. The expression levels of PER3 were also analyzed using published microarray profiles from > 400 breast cancer samples. Finally, the effect of loss of Per3 on tumor susceptibility was tested using two mouse models of breast cancer. RESULTS: Deletion of PER3 is directly related to tumor recurrence in patients with estrogen receptor (ER) - positive breast cancers treated with tamoxifen. Low expression of PER3 mRNA is associated with poor prognosis, particularly in a subset of tumors that are ER positive, and either luminal A or ERBB2-positive tumors. Mice deficient in Per3 showed increased susceptibility to breast cancer induced by carcinogen treatment or by overexpression of Erbb2. CONCLUSION: Disruption of PER3 function may serve as an indicator of probability of tumor recurrence in patients with ER-positive tumors. Further investigations of this pathway may reveal links between deregulation of sleep homeostasis and breast tumorigenesis.


Assuntos
Neoplasias da Mama/genética , Cromossomos Humanos Par 1/genética , Proteínas Circadianas Period/genética , Animais , Neoplasias da Mama/metabolismo , Neoplasias da Mama/terapia , Modelos Animais de Doenças , Feminino , Dosagem de Genes , Expressão Gênica , Predisposição Genética para Doença , Humanos , Camundongos , Recidiva Local de Neoplasia , Prognóstico , Receptores de Estrogênio , Deleção de Sequência , Análise de Sobrevida
17.
Science ; 321(5895): 1499-502, 2008 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-18787170

RESUMO

The enzyme mTOR (mammalian target of rapamycin) is a major target for therapeutic intervention to treat many human diseases, including cancer, but very little is known about the processes that control levels of mTOR protein. Here, we show that mTOR is targeted for ubiquitination and consequent degradation by binding to the tumor suppressor protein FBXW7. Human breast cancer cell lines and primary tumors showed a reciprocal relation between loss of FBXW7 and deletion or mutation of PTEN (phosphatase and tensin homolog), which also activates mTOR. Tumor cell lines harboring deletions or mutations in FBXW7 are particularly sensitive to rapamycin treatment, which suggests that loss of FBXW7 may be a biomarker for human cancers susceptible to treatment with inhibitors of the mTOR pathway.


Assuntos
Neoplasias da Mama/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas F-Box/metabolismo , PTEN Fosfo-Hidrolase/metabolismo , Proteínas Quinases/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Animais , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Proteínas de Ciclo Celular/genética , Linhagem Celular , Linhagem Celular Tumoral , Proteínas F-Box/genética , Proteína 7 com Repetições F-Box-WD , Deleção de Genes , Dosagem de Genes , Inativação Gênica , Genes Supressores de Tumor , Humanos , Camundongos , Camundongos Nus , Mutação , Transplante de Neoplasias , PTEN Fosfo-Hidrolase/genética , Fosforilação , Ligação Proteica , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Sirolimo/farmacologia , Sirolimo/uso terapêutico , Serina-Treonina Quinases TOR , Transfecção , Ubiquitina-Proteína Ligases/genética , Ubiquitinação
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