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1.
Nat Commun ; 11(1): 4673, 2020 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-32938917

RESUMO

RAS-MAPK signaling mediates processes critical to normal development including cell proliferation, survival, and differentiation. Germline mutation of RAS-MAPK genes lead to the Noonan-spectrum of syndromes. Here, we present a patient affected by a 6p-interstitial microdeletion with unknown underlying molecular etiology. Examination of 6p-interstitial microdeletion cases reveals shared clinical features consistent with Noonan-spectrum disorders including short stature, facial dysmorphia and cardiovascular abnormalities. We find the RAS-responsive element binding protein-1 (RREB1) is the common deleted gene in multiple 6p-interstitial microdeletion cases. Rreb1 hemizygous mice display orbital hypertelorism and cardiac hypertrophy phenocopying the human syndrome. Rreb1 haploinsufficiency leads to sensitization of MAPK signaling. Rreb1 recruits Sin3a and Kdm1a to control H3K4 methylation at MAPK pathway gene promoters. Haploinsufficiency of SIN3A and mutations in KDM1A cause syndromes similar to RREB1 haploinsufficiency suggesting genetic perturbation of the RREB1-SIN3A-KDM1A complex represents a new category of RASopathy-like syndromes arising through epigenetic reprogramming of MAPK pathway genes.


Assuntos
Proteínas de Ligação a DNA/genética , Haploinsuficiência , Sistema de Sinalização das MAP Quinases/genética , Síndrome de Noonan/etiologia , Fatores de Transcrição/genética , Proteínas ras/metabolismo , Anormalidades Múltiplas/genética , Animais , Deleção Cromossômica , Cromossomos Humanos Par 6 , Proteínas de Ligação a DNA/metabolismo , Epigênese Genética , Feminino , Fatores de Crescimento de Fibroblastos/genética , Fatores de Crescimento de Fibroblastos/metabolismo , Histona Desmetilases/genética , Histona Desmetilases/metabolismo , Histonas/metabolismo , Humanos , Masculino , Metilação , Camundongos Endogâmicos C57BL , Camundongos Knockout , Complexo Correpressor Histona Desacetilase e Sin3/genética , Complexo Correpressor Histona Desacetilase e Sin3/metabolismo , Fatores de Transcrição/metabolismo , Proteínas ras/genética
2.
Nat Commun ; 11(1): 3409, 2020 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-32641778

RESUMO

Pancreatic ductal adenocarcinoma (PDAC) is associated with high mortality and therapy resistance. Here, we show that low expression of κB-Ras GTPases is frequently detected in PDAC and correlates with higher histologic grade. In a model of KRasG12D-driven PDAC, loss of κB-Ras accelerates tumour development and shortens median survival. κB-Ras deficiency promotes acinar-to-ductal metaplasia (ADM) during tumour initiation as well as tumour progression through intrinsic effects on proliferation and invasion. κB-Ras proteins are also required for acinar regeneration after pancreatitis, demonstrating a general role in control of plasticity. Molecularly, upregulation of Ral GTPase activity and Sox9 expression underlies the observed phenotypes, identifying a previously unrecognized function of Ral signalling in ADM. Our results provide evidence for a tumour suppressive role of κB-Ras proteins and highlight low κB-Ras levels and consequent loss of Ral control as risk factors, thus emphasizing the necessity for therapeutic options that allow interference with Ral-driven signalling.


Assuntos
Células Acinares/metabolismo , Carcinoma Ductal Pancreático/genética , GTP Fosfo-Hidrolases/genética , Neoplasias Pancreáticas/genética , Pancreatite/genética , Proteínas/genética , Células Acinares/patologia , Idoso , Animais , Carcinoma Ductal Pancreático/metabolismo , Carcinoma Ductal Pancreático/patologia , Linhagem Celular Tumoral , Feminino , GTP Fosfo-Hidrolases/metabolismo , Regulação da Expressão Gênica , Humanos , Proteínas I-kappa B/genética , Proteínas I-kappa B/metabolismo , Estimativa de Kaplan-Meier , Masculino , Metaplasia/genética , Metaplasia/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pessoa de Meia-Idade , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia , Pancreatite/metabolismo , Proteínas/metabolismo , Fatores de Transcrição SOX9/genética , Fatores de Transcrição SOX9/metabolismo , Proteínas ral de Ligação ao GTP/genética , Proteínas ral de Ligação ao GTP/metabolismo , Proteínas ras/genética , Proteínas ras/metabolismo
3.
Nat Commun ; 11(1): 3568, 2020 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-32678085

RESUMO

Dissemination of transformed cells is a key process in metastasis. Despite its importance, how transformed cells disseminate from an intact tissue and enter the circulation is poorly understood. Here, we use a fully developed tissue, Drosophila midgut, and describe the morphologically distinct steps and the cellular events occurring over the course of RasV12-transformed cell dissemination. Notably, RasV12-transformed cells formed the Actin- and Cortactin-rich invasive protrusions that were important for breaching the extracellular matrix (ECM) and visceral muscle. Furthermore, we uncovered the essential roles of the mechanosensory channel Piezo in orchestrating dissemination of RasV12-transformed cells. Collectively, our study establishes an in vivo model for studying how transformed cells migrate out from a complex tissue and provides unique insights into the roles of Piezo in invasive cell behavior.


Assuntos
Proteínas de Drosophila/metabolismo , Canais Iônicos/metabolismo , Mecanotransdução Celular , Invasividade Neoplásica/patologia , Proteínas ras/metabolismo , Animais , Membrana Basal/metabolismo , Membrana Basal/patologia , Transformação Celular Neoplásica , Modelos Animais de Doenças , Drosophila , Proteínas de Drosophila/genética , Vesículas Extracelulares/metabolismo , Trato Gastrointestinal/patologia , Genes ras , Canais Iônicos/genética , Metástase Neoplásica/patologia , Podossomos/metabolismo , Proteínas ras/genética
4.
Proc Natl Acad Sci U S A ; 117(29): 16938-16948, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32616570

RESUMO

Despite nearly four decades of effort, broad inhibition of oncogenic RAS using small-molecule approaches has proven to be a major challenge. Here we describe the development of a pan-RAS biologic inhibitor composed of the RAS-RAP1-specific endopeptidase fused to the protein delivery machinery of diphtheria toxin. We show that this engineered chimeric toxin irreversibly cleaves and inactivates intracellular RAS at low picomolar concentrations terminating downstream signaling in receptor-bearing cells. Furthermore, we demonstrate in vivo target engagement and reduction of tumor burden in three mouse xenograft models driven by either wild-type or mutant RAS Intracellular delivery of a potent anti-RAS biologic through a receptor-mediated mechanism represents a promising approach to developing RAS therapeutics against a broad array of cancers.


Assuntos
Toxina Diftérica/metabolismo , Endopeptidases/metabolismo , Neoplasias Experimentais/tratamento farmacológico , Proteólise , Proteínas rap1 de Ligação ao GTP/metabolismo , Proteínas ras/metabolismo , Animais , Antineoplásicos/uso terapêutico , Células Cultivadas , Toxina Diftérica/química , Toxina Diftérica/genética , Endopeptidases/química , Endopeptidases/genética , Feminino , Células HCT116 , Humanos , Masculino , Camundongos , Camundongos Nus , Mutação , Sinais Direcionadores de Proteínas , Proteínas Recombinantes/uso terapêutico , Proteínas ras/genética
5.
Am J Chin Med ; 48(5): 1221-1241, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32668964

RESUMO

Tamoxifen is one of the most common hormone therapy drug for estrogen receptor (ER)-positive breast cancer. Tumor cells with drug resistance often cause recurrence and metastasis in cancer patients. Luteolin is a natural compound found from various types of vegetables and exhibit anticancer activity in different cancers. This study demonstrated that luteolin inhibits the proliferation and induces apoptosis of tamoxifen-resistant ER-positive breast cancer cells. Luteolin also causes cell cycle arrest at the G2/M phase and decreases mitochondrial membrane potential. Besides, luteolin reduces the levels of activated PI3K/AKT/mTOR signaling pathway. The combination treatment of luteolin and PI3K, AKT, or mTOR inhibitors synergistically increases apoptosis in tamoxifen-resistant ER-positive breast cancer cells. Ras gene family (K-Ras, H-Ras, and N-Ras), an activator of PI3K, was transcriptionally repressed by luteolin via induction of tumor suppressor mixed-lineage leukemia 3 (MLL3) expression. MLL3 increases the level of monomethylation of Histone 3 Lysine 4 on the enhancer and promoter region of Ras genes, thus causes repression of Ras expressions. Our finding implies that luteolin was a promising natural agent against tamoxifen resistance of breast cancer.


Assuntos
Apoptose/efeitos dos fármacos , Apoptose/genética , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Proteínas de Ligação a DNA/fisiologia , Expressão Gênica/efeitos dos fármacos , Luteolina/farmacologia , Antineoplásicos Fitogênicos , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/genética , Regulação para Baixo/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Feminino , Humanos , Metilação/efeitos dos fármacos , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR , Tamoxifeno/farmacologia , Proteínas ras/genética , Proteínas ras/metabolismo
6.
Adv Cancer Res ; 148: 69-146, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32723567

RESUMO

RAS was identified as a human oncogene in the early 1980s and subsequently found to be mutated in nearly 30% of all human cancers. More importantly, RAS plays a central role in driving tumor development and maintenance. Despite decades of effort, there remain no FDA approved drugs that directly inhibit RAS. The prevalence of RAS mutations in cancer and the lack of effective anti-RAS therapies stem from RAS' core role in growth factor signaling, unique structural features, and biochemistry. However, recent advances have brought promising new drugs to clinical trials and shone a ray of hope in the field. Here, we will exposit the details of RAS biology that illustrate its key role in cell signaling and shed light on the difficulties in therapeutically targeting RAS. Furthermore, past and current efforts to develop RAS inhibitors will be discussed in depth.


Assuntos
Antineoplásicos/uso terapêutico , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Proteínas ras/metabolismo , Animais , Antineoplásicos/farmacologia , Humanos , Terapia de Alvo Molecular , Mutação , Neoplasias/patologia , Oncogenes , Transdução de Sinais/fisiologia , Proteínas ras/antagonistas & inibidores , Proteínas ras/genética
7.
Nature ; 583(7815): 265-270, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32581361

RESUMO

Cancers arise through the acquisition of oncogenic mutations and grow by clonal expansion1,2. Here we reveal that most mutagenic DNA lesions are not resolved into a mutated DNA base pair within a single cell cycle. Instead, DNA lesions segregate, unrepaired, into daughter cells for multiple cell generations, resulting in the chromosome-scale phasing of subsequent mutations. We characterize this process in mutagen-induced mouse liver tumours and show that DNA replication across persisting lesions can produce multiple alternative alleles in successive cell divisions, thereby generating both multiallelic and combinatorial genetic diversity. The phasing of lesions enables accurate measurement of strand-biased repair processes, quantification of oncogenic selection and fine mapping of sister-chromatid-exchange events. Finally, we demonstrate that lesion segregation is a unifying property of exogenous mutagens, including UV light and chemotherapy agents in human cells and tumours, which has profound implications for the evolution and adaptation of cancer genomes.


Assuntos
Segregação de Cromossomos/genética , Evolução Molecular , Genoma/genética , Neoplasias/genética , Alelos , Animais , Reparo do DNA , Replicação do DNA , Receptores ErbB/metabolismo , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , Masculino , Camundongos , Mutação , Neoplasias/patologia , Seleção Genética , Transdução de Sinais , Troca de Cromátide Irmã , Transcrição Genética , Quinases raf/metabolismo , Proteínas ras/metabolismo
8.
Life Sci ; 256: 117936, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32531376

RESUMO

AIMS: The regulation of the Ras-ERK pathway is the crucial point in pancreatic carcinogenesis, and the Ras kinase is an essential regulatory upstream signal molecule of the ERK1/2 pathway. H3K9ac is a vital histone modification, but its specific role in pancreatic cancer remains unclear. This research aims to study whether the modification level of H3K9ac can regulate the characteristic phenotype of the pancreatic cancer cells by affecting the downstream expression, proliferation, migration, and other related genes. MAIN METHODS: The RasG12V/T35S were used to transfect pancreatic cancer cells, and the levels of phosphorylated ERK1/2 and H3K9ac were detected by western blotting. The colony formation assay, transwell assay, and chromatin immunoprecipitation assay were used to study cell viability, migration, and the downstream genes of the ERK1/2 pathway. KEY FINDINGS: The results showed that Ras ERK1/2 reduced H3K9ac expression in ASPC-1 cells, and H3K9ac significantly repressed the viability of cells, colony formation, and ASPC-1 cell movement induced by Ras ERK1/2. Besides, HDAC1 silencing increased H3K9ac expression, and changed the effect of Ras ERK1/2 on ASPC-1 cells proliferation, its movement, and mRNAs of ERK1/2 downstream genes. Moreover, Ras ERK1/2 inhibited H3K9ac expression by the degradation of PCAF via MDM2. SIGNIFICANCE: Ras ERK1/2 promotes pancreatic carcinogenesis cell movement, through down-regulating H3K9ac via MDM2 mediated PCAF degradation.


Assuntos
Carcinogênese/patologia , Histonas/metabolismo , Lisina/metabolismo , Sistema de Sinalização das MAP Quinases , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia , Fatores de Transcrição de p300-CBP/metabolismo , Proteínas ras/metabolismo , Acetilação , Carcinogênese/genética , Carcinogênese/metabolismo , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , Inativação Gênica , Histona Desacetilase 1/metabolismo , Humanos , Neoplasias Pancreáticas/genética , Fenótipo , Proteólise , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Transdução de Sinais , Transcrição Genética
9.
PLoS Genet ; 16(6): e1008838, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32544191

RESUMO

Reactive oxygen species (ROS) are signalling molecules whose study in intact organisms has been hampered by their potential toxicity. This has prevented a full understanding of their role in organismal processes such as development, aging and disease. In Caenorhabditis elegans, the development of the vulva is regulated by a signalling cascade that includes LET-60ras (homologue of mammalian Ras), MPK-1 (ERK1/2) and LIN-1 (an ETS transcription factor). We show that both mitochondrial and cytoplasmic ROS act on a gain-of-function (gf) mutant of the LET-60ras protein through a redox-sensitive cysteine (C118) previously identified in mammals. We show that the prooxidant paraquat as well as isp-1, nuo-6 and sod-2 mutants, which increase mitochondrial ROS, inhibit the activity of LET-60rasgf on vulval development. In contrast, the antioxidant NAC and loss of sod-1, both of which decrease cytoplasmic H202, enhance the activity of LET-60rasgf. CRISPR replacement of C118 with a non-oxidizable serine (C118S) stimulates LET-60rasgf activity, whereas replacement of C118 with aspartate (C118D), which mimics a strongly oxidised cysteine, inhibits LET-60rasgf. These data strongly suggest that C118 is oxidized by cytoplasmic H202 generated from dismutation of mitochondrial and/or cytoplasmic superoxide, and that this oxidation inhibits LET-60ras. This contrasts with results in cultured mammalian cells where it is mostly nitric oxide, which is not found in worms, that oxidizes C118 and activates Ras. Interestingly, PQ, NAC and the C118S mutation do not act on the phosphorylation of MPK-1, suggesting that oxidation of LET-60ras acts on an as yet uncharacterized MPK-1-independent pathway. We also show that elevated cytoplasmic superoxide promotes vulva formation independently of C118 of LET-60ras and downstream of LIN-1. Finally, we uncover a role for the NADPH oxidases (BLI-3 and DUOX-2) and their redox-sensitive activator CED-10rac in stimulating vulva development. Thus, there are at least three genetically separable pathways by which ROS regulates vulval development.


Assuntos
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/crescimento & desenvolvimento , Regulação da Expressão Gênica no Desenvolvimento , Peróxidos/metabolismo , Vulva/crescimento & desenvolvimento , Proteínas ras/genética , Animais , Animais Geneticamente Modificados , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Feminino , Mutação com Ganho de Função , Genes de Helmintos/genética , Oxirredução , Oxirredutases/metabolismo , Peróxidos/análise , Transdução de Sinais/genética , Fatores de Transcrição/metabolismo , Proteínas rac de Ligação ao GTP/metabolismo , Proteínas ras/metabolismo
10.
F1000Res ; 92020.
Artigo em Inglês | MEDLINE | ID: mdl-32518628

RESUMO

A complex molecular machinery converges on the surface of lysosomes to ensure that the growth-promoting signaling mediated by mechanistic target of rapamycin complex 1 (mTORC1) is tightly controlled by the availability of nutrients and growth factors. The final step in this activation process is dependent on Rheb, a small GTPase that binds to mTOR and allosterically activates its kinase activity. Here we review the mechanisms that determine the subcellular localization of Rheb (and the closely related RhebL1 protein) as well as the significance of these mechanisms for controlling mTORC1 activation. In particular, we explore how the relatively weak membrane interactions conferred by C-terminal farnesylation are critical for the ability of Rheb to activate mTORC1. In addition to supporting transient membrane interactions, Rheb C-terminal farnesylation also supports an interaction between Rheb and the δ subunit of phosphodiesterase 6 (PDEδ). This interaction provides a potential mechanism for targeting Rheb to membranes that contain Arl2, a small GTPase that triggers the release of prenylated proteins from PDEδ. The minimal membrane targeting conferred by C-terminal farnesylation of Rheb and RhebL1 distinguishes them from other members of the Ras superfamily that possess additional membrane interaction motifs that work with farnesylation for enrichment on the specific subcellular membranes where they engage key effectors. Finally, we highlight diversity in Rheb membrane targeting mechanisms as well as the potential for alternative mTORC1 activation mechanisms across species.


Assuntos
Lisossomos/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Proteína Enriquecida em Homólogo de Ras do Encéfalo/metabolismo , Transdução de Sinais , Humanos , Peptídeos e Proteínas de Sinalização Intercelular , Proteínas ras/metabolismo
11.
Mol Cell ; 78(6): 1178-1191.e6, 2020 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-32485148

RESUMO

The RAS-ERK/MAPK (RAS-extracellular signal-regulated kinase/mitogen-activated protein kinase) pathway integrates growth-promoting signals to stimulate cell growth and proliferation, at least in part, through alterations in metabolic gene expression. However, examples of direct and rapid regulation of the metabolic pathways by the RAS-ERK pathway remain elusive. We find that physiological and oncogenic ERK signaling activation leads to acute metabolic flux stimulation through the de novo purine synthesis pathway, thereby increasing building block availability for RNA and DNA synthesis, which is required for cell growth and proliferation. We demonstrate that ERK2, but not ERK1, phosphorylates the purine synthesis enzyme PFAS (phosphoribosylformylglycinamidine synthase) at T619 in cells to stimulate de novo purine synthesis. The expression of nonphosphorylatable PFAS (T619A) decreases purine synthesis, RAS-dependent cancer cell-colony formation, and tumor growth. Thus, ERK2-mediated PFAS phosphorylation facilitates the increase in nucleic acid synthesis required for anabolic cell growth and proliferation.


Assuntos
Carbono-Nitrogênio Ligases com Glutamina como Doadora de N-Amida/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Purinas/biossíntese , Células A549 , Animais , Carbono-Nitrogênio Ligases com Glutamina como Doadora de N-Amida/genética , Ciclo Celular/fisiologia , Linhagem Celular Tumoral , Proliferação de Células/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Células HeLa , Humanos , Sistema de Sinalização das MAP Quinases/fisiologia , Fosforilação , Purinas/metabolismo , Transdução de Sinais/fisiologia , Proteínas ras/metabolismo
12.
Nat Commun ; 11(1): 3233, 2020 06 26.
Artigo em Inglês | MEDLINE | ID: mdl-32591521

RESUMO

Tumour-associated KRAS mutations are the most prevalent in the three RAS-family isoforms and involve many different amino-acids. Therefore, molecules able to interfere with mutant KRAS protein are potentially important for wide-ranging tumour therapy. We describe the engineering of two RAS degraders based on protein macromolecules (macrodrugs) fused to specific E3 ligases. A KRAS-specific DARPin fused to the VHL E3 ligase is compared to a pan-RAS intracellular single domain antibody (iDAb) fused to the UBOX domain of the CHIP E3 ligase. We demonstrate that while the KRAS-specific DARPin degrader induces specific proteolysis of both mutant and wild type KRAS, it only inhibits proliferation of cancer cells expressing mutant KRAS in vitro and in vivo. Pan-RAS protein degradation, however, affects proliferation irrespective of the RAS mutation. These data show that specific KRAS degradation is an important therapeutic strategy to affect tumours expressing any of the range of KRAS mutations.


Assuntos
Substâncias Macromoleculares/metabolismo , Proteínas Mutantes/metabolismo , Mutação/genética , Neoplasias/metabolismo , Proteólise , Proteínas ras/metabolismo , Animais , Apoptose , Linhagem Celular Tumoral , Proliferação de Células , Humanos , Camundongos Nus , Domínios Proteicos , Engenharia de Proteínas , Transdução de Sinais
13.
PLoS Genet ; 16(6): e1008715, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32559233

RESUMO

Dysregulation of the Ras oncogene in development causes developmental disorders, "Rasopathies," whereas mutational activation or amplification of Ras in differentiated tissues causes cancer. Rabex-5 (also called RabGEF1) inhibits Ras by promoting Ras mono- and di-ubiquitination. We report here that Rabex-5-mediated Ras ubiquitination requires Ras Tyrosine 4 (Y4), a site of known phosphorylation. Ras substitution mutants insensitive to Y4 phosphorylation did not undergo Rabex-5-mediated ubiquitination in cells and exhibited Ras gain-of-function phenotypes in vivo. Ras Y4 phosphomimic substitution increased Rabex-5-mediated ubiquitination in cells. Y4 phosphomimic substitution in oncogenic Ras blocked the morphological phenotypes associated with oncogenic Ras in vivo dependent on the presence of Rabex-5. We developed polyclonal antibodies raised against an N-terminal Ras peptide phosphorylated at Y4. These anti-phospho-Y4 antibodies showed dramatic recognition of recombinant wild-type Ras and RasG12V proteins when incubated with JAK2 or SRC kinases but not of RasY4F or RasY4F,G12V recombinant proteins suggesting that JAK2 and SRC could promote phosphorylation of Ras proteins at Y4 in vitro. Anti-phospho-Y4 antibodies also showed recognition of RasG12V protein, but not wild-type Ras, when incubated with EGFR. A role for JAK2, SRC, and EGFR (kinases with well-known roles to activate signaling through Ras), to promote Ras Y4 phosphorylation could represent a feedback mechanism to limit Ras activation and thus establish Ras homeostasis. Notably, rare variants of Ras at Y4 have been found in cerebellar glioblastomas. Therefore, our work identifies a physiologically relevant Ras ubiquitination signal and highlights a requirement for Y4 for Ras inhibition by Rabex-5 to maintain Ras pathway homeostasis and to prevent tissue transformation.


Assuntos
Proteínas de Drosophila/metabolismo , Transdução de Sinais , Ubiquitina-Proteína Ligases/metabolismo , Proteínas ras/metabolismo , Animais , Células Cultivadas , Sequência Conservada , Drosophila , Receptores ErbB/metabolismo , Retroalimentação Fisiológica , Janus Quinase 2/metabolismo , Fosforilação , Tirosina/química , Tirosina/genética , Ubiquitinação , Proteínas ras/química , Proteínas ras/genética , Quinases da Família src/metabolismo
14.
Proc Natl Acad Sci U S A ; 117(22): 12121-12130, 2020 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-32424096

RESUMO

HRAS, NRAS, and KRAS4A/KRAS4B comprise the RAS family of small GTPases that regulate signaling pathways controlling cell proliferation, differentiation, and survival. RAS pathway abnormalities cause developmental disorders and cancers. We found that KRAS4B colocalizes on the cell membrane with other RAS isoforms and a subset of prenylated small GTPase family members using a live-cell quantitative split luciferase complementation assay. RAS protein coclustering is mainly mediated by membrane association-facilitated interactions (MAFIs). Using the RAS-RBD (CRAF RAS binding domain) interaction as a model system, we showed that MAFI alone is not sufficient to induce RBD-mediated RAS inhibition. Surprisingly, we discovered that high-affinity membrane-targeted RAS binding proteins inhibit RAS activity and deplete RAS proteins through an autophagosome-lysosome-mediated degradation pathway. Our results provide a mechanism for regulating RAS activity and protein levels, a more detailed understanding of which should lead to therapeutic strategies for inhibiting and depleting oncogenic RAS proteins.


Assuntos
Autofagossomos/metabolismo , Membrana Celular/metabolismo , Lisossomos/metabolismo , Proteínas ras/metabolismo , Humanos , Modelos Moleculares , Domínios e Motivos de Interação entre Proteínas , Isoformas de Proteínas , Transdução de Sinais
15.
Am J Physiol Endocrinol Metab ; 319(1): E232-E244, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32369417

RESUMO

Voltage-gated Ca2+ (CaV) channels are expressed in endocrine cells where they contribute to hormone secretion. Diverse chemical messengers, including epidermal growth factor (EGF), are known to affect the expression of CaV channels. Previous studies have shown that EGF increases Ca2+ currents in GH3 pituitary cells by increasing the number of high voltage-activated (HVA) CaV channels at the cell membrane, which results in enhanced prolactin (PRL) secretion. However, little is known regarding the mechanisms underlying this regulation. Here, we show that EGF actually increases the expression of the CaVα2δ-1 subunit, a key molecular component of HVA channels. The analysis of the gene promoter encoding CaVα2δ-1 (CACNA2D1) revealed binding sites for transcription factors activated by the Ras/Raf/MEK/ERK signaling cascade. Chromatin immunoprecipitation and site-directed mutagenesis showed that ELK-1 is crucial for the transcriptional regulation of CACNA2D1 in response to EGF. Furthermore, we found that EGF increases the membrane expression of CaVα2δ-1 and that ELK-1 overexpression increases HVA current density, whereas ELK-1 knockdown decreases the functional expression of the channels. Hormone release assays revealed that CaVα2δ-1 overexpression increases PRL secretion. These results suggest a mechanism for how EGF, by activating the Ras/Raf/MEK/ERK/ELK-1 pathway, may influence the expression of HVA channels and the secretory behavior of pituitary cells.


Assuntos
Canais de Cálcio Tipo L/genética , Fator de Crescimento Epidérmico/metabolismo , Regulação da Expressão Gênica , Sistema de Sinalização das MAP Quinases/genética , Proteínas Elk-1 do Domínio ets/genética , Quinases raf/genética , Proteínas ras/genética , Animais , Canais de Cálcio Tipo L/metabolismo , Linhagem Celular Tumoral , Imunoprecipitação da Cromatina , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/genética , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Técnicas de Silenciamento de Genes , Mutagênese Sítio-Dirigida , Regiões Promotoras Genéticas , Ratos , Transdução de Sinais , Proteínas Elk-1 do Domínio ets/metabolismo , Quinases raf/metabolismo , Proteínas ras/metabolismo
16.
Nat Commun ; 11(1): 2189, 2020 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-32366847

RESUMO

While most testicular germ cell tumours (TGCTs) exhibit exquisite sensitivity to platinum chemotherapy, ~10% are platinum resistant. To gain insight into the underlying mechanisms, we undertake whole exome sequencing and copy number analysis in 40 tumours from 26 cases with platinum-resistant TGCT, and combine this with published genomic data on an additional 624 TGCTs. We integrate analyses for driver mutations, mutational burden, global, arm-level and focal copy number (CN) events, and SNV and CN signatures. Albeit preliminary and observational in nature, these analyses provide support for a possible mechanistic link between early driver mutations in RAS and KIT and the widespread copy number events by which TGCT is characterised.


Assuntos
Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Genômica/métodos , Neoplasias Embrionárias de Células Germinativas/tratamento farmacológico , Platina/uso terapêutico , Neoplasias Testiculares/tratamento farmacológico , Variações do Número de Cópias de DNA , Predisposição Genética para Doença/genética , Humanos , Masculino , Mutação , Neoplasias Embrionárias de Células Germinativas/genética , Neoplasias Embrionárias de Células Germinativas/metabolismo , Compostos Organoplatínicos/uso terapêutico , Proteínas Proto-Oncogênicas c-kit/genética , Proteínas Proto-Oncogênicas c-kit/metabolismo , Transdução de Sinais/genética , Neoplasias Testiculares/genética , Neoplasias Testiculares/metabolismo , Sequenciamento Completo do Exoma/métodos , Proteínas ras/genética , Proteínas ras/metabolismo
17.
PLoS One ; 15(4): e0231990, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32320453

RESUMO

Environmental mold (fungus) exposure poses a significant threat to public health by causing illnesses ranging from invasive fungal diseases in immune compromised individuals to allergic hypertensive diseases such as asthma and asthma exacerbation in otherwise healthy people. However, the molecular pathogenesis has not been completely understood, and treatment options are limited. Due to its thermo-tolerance to the normal human body temperature, Aspergillus. fumigatus (A.fumigatus) is one of the most important human pathogens to cause different lung fungal diseases including fungal asthma. Airway obstruction and hyperresponsiveness caused by mucus overproduction are the hallmarks of many A.fumigatus induced lung diseases. To understand the underlying molecular mechanism, we have utilized a well-established A.fumigatus extracts (AFE) model to elucidate downstream signal pathways that mediate A.fumigatus induced mucin production in airway epithelial cells. AFE was found to stimulate time- and dose-dependent increase of major airway mucin gene expression (MUC5AC and MUC5B) partly via the elevation of their promoter activities. We also demonstrated that EGFR was required but not sufficient for AFE-induced mucin expression, filling the paradoxical gap from a previous study using the same model. Furthermore, we showed that fungal proteases in AFE were responsible for mucin induction by activating a Ras/Raf1/ERK signaling pathway. Ca2+ signaling, but ROS, both of which were stimulated by fungal proteases, was an indispensable determinant for ERK activation and mucin induction. The discovery of this novel pathway likely contributes to our understanding of the pathogenesis of fungal sensitization in allergic diseases such as fungal asthma.


Assuntos
Aspergillus fumigatus/enzimologia , Proteínas Fúngicas/toxicidade , Interações Hospedeiro-Patógeno/fisiologia , Mucinas/metabolismo , Peptídeo Hidrolases/toxicidade , Aspergillus fumigatus/patogenicidade , Cálcio/metabolismo , Linhagem Celular , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Receptores ErbB/metabolismo , Humanos , Pulmão/citologia , Sistema de Sinalização das MAP Quinases , Mucina-5AC/genética , Mucina-5AC/metabolismo , Mucina-5B/genética , Mucina-5B/metabolismo , Mucinas/genética , Proteínas Proto-Oncogênicas c-raf/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteínas ras/metabolismo
18.
Metabolism ; 108: 154250, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32335074

RESUMO

BACKGROUND: Chronic steroid treatment causes an increase in visceral adiposity and osteoporosis. It is believed that steroids may alter a balance between differentiation of mesenchymal stem cells (MSCs) into either adipocytes or osteoblasts; however, the detailed molecular mechanisms are unclear. We previously identified Dexras1 as a critical factor that potentiates adipogenesis in response to glucocorticoids. Thus, in this study, we investigated the role of Dexras1 in maintaining the balance between chronic steroid treatment-associated adipogenesis and osteoporosis. MATERIAL AND METHODS: We treated wild type (WT) and Dexras1 knockout (KO) mice with dexamethasone for five weeks followed by 60% HFD for additional two weeks with dexamethasone. The changes of glucocorticoid-induced body weight gain and osteoporosis were analyzed. Bone marrow derived stromal cells (BMSCs) and mouse embryonic fibroblasts (MEFs) extracted from WT and Dexras1 KO mice, as well as MC3T3-E1 pre-osteoblasts and osteoclasts differentiated from RAW264.7 were analyzed to further define the role of Dexras1 in osteoblasts and osteoclasts. RESULTS: Dual-energy X-ray absorptiometry and micro-computed tomography analyses in murine femurs revealed that Dexras1 deficiency was associated with increased osteogenesis, concurrent with reduced adipogenesis. Furthermore, Dexras1 deficiency promoted osteogenesis of BMSCs and MEFs in vitro, suggesting that Dexras1 deficiency prevents steroid-induced osteoporosis. We also observed that Dexras1 downregulated SMAD signaling pathways, which reduced the osteogenic differentiation capacity of pre-osteoblast MC3T3-E1 cells into mature osteoblasts. CONCLUSION: We propose that Dexras1 is critical for maintaining the equilibrium between adipogenesis and osteogenesis upon steroid treatment.


Assuntos
Adipogenia/fisiologia , Osteogênese/fisiologia , Proteínas ras/metabolismo , Células 3T3 , Adipócitos/metabolismo , Animais , Diferenciação Celular/fisiologia , Linhagem Celular , Fêmur/metabolismo , Glucocorticoides/metabolismo , Masculino , Células-Tronco Mesenquimais/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Osteoblastos/metabolismo , Osteoclastos/metabolismo , Osteoporose/metabolismo , Células RAW 264.7 , Transdução de Sinais/fisiologia
19.
PLoS Comput Biol ; 16(3): e1007147, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32119655

RESUMO

Targeted cancer therapies are powerful alternatives to chemotherapies or can be used complementary to these. Yet, the response to targeted treatments depends on a variety of factors, including mutations and expression levels, and therefore their outcome is difficult to predict. Here, we develop a mechanistic model of gastric cancer to study response and resistance factors for cetuximab treatment. The model captures the EGFR, ERK and AKT signaling pathways in two gastric cancer cell lines with different mutation patterns. We train the model using a comprehensive selection of time and dose response measurements, and provide an assessment of parameter and prediction uncertainties. We demonstrate that the proposed model facilitates the identification of causal differences between the cell lines. Furthermore, our study shows that the model provides predictions for the responses to different perturbations, such as knockdown and knockout experiments. Among other results, the model predicted the effect of MET mutations on cetuximab sensitivity. These predictive capabilities render the model a basis for the assessment of gastric cancer signaling and possibly for the development and discovery of predictive biomarkers.


Assuntos
Cetuximab/farmacologia , Neoplasias Gástricas/genética , Anticorpos Monoclonais/genética , Anticorpos Monoclonais Humanizados , Antineoplásicos/farmacologia , Biomarcadores Tumorais/metabolismo , Linhagem Celular Tumoral/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Cetuximab/genética , Cetuximab/metabolismo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Receptores ErbB/metabolismo , Humanos , Modelos Biológicos , Modelos Estatísticos , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Fatores R , Transdução de Sinais/fisiologia , Neoplasias Gástricas/tratamento farmacológico , Proteínas ras/metabolismo
20.
Mutat Res ; 819-820: 111690, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32120136

RESUMO

The serine/threonine kinase AKT, also known as protein kinase B (PKB), is the major substrate to phosphoinositide 3-kinase (PI3K) and consists of three paralogs: AKT1 (PKBα), AKT2 (PKBß) and AKT3 (PKBγ). The PI3K/AKT pathway is normally activated by binding of ligands to membrane-bound receptor tyrosine kinases (RTKs) as well as downstream to G-protein coupled receptors and integrin-linked kinase. Through multiple downstream substrates, activated AKT controls a wide variety of cellular functions including cell proliferation, survival, metabolism, and angiogenesis in both normal and malignant cells. In human cancers, the PI3K/AKT pathway is most frequently hyperactivated due to mutations and/or overexpression of upstream components. Aberrant expression of RTKs, gain of function mutations in PIK3CA, RAS, PDPK1, and AKT itself, as well as loss of function mutation in AKT phosphatases are genetic lesions that confer hyperactivation of AKT. Activated AKT stimulates DNA repair, e.g. double strand break repair after radiotherapy. Likewise, AKT attenuates chemotherapy-induced apoptosis. These observations suggest that a crucial link exists between AKT and DNA damage. Thus, AKT could be a major predictive marker of conventional cancer therapy, molecularly targeted therapy, and immunotherapy for solid tumors. In this review, we summarize the current understanding by which activated AKT mediates resistance to cancer treatment modalities, i.e. radiotherapy, chemotherapy, and RTK targeted therapy. Next, the effect of AKT on response of tumor cells to RTK targeted strategies will be discussed. Finally, we will provide a brief summary on the clinical trials of AKT inhibitors in combination with radiochemotherapy, RTK targeted therapy, and immunotherapy.


Assuntos
DNA de Neoplasias/genética , Regulação Neoplásica da Expressão Gênica , Terapia de Alvo Molecular/métodos , Neoplasias/terapia , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Quinases Dependentes de 3-Fosfoinositídeo/genética , Proteínas Quinases Dependentes de 3-Fosfoinositídeo/metabolismo , Antineoplásicos/uso terapêutico , Ensaios Clínicos como Assunto , Dano ao DNA , Reparo do DNA/efeitos dos fármacos , DNA de Neoplasias/metabolismo , Raios gama/uso terapêutico , Humanos , Isoenzimas/antagonistas & inibidores , Isoenzimas/genética , Isoenzimas/metabolismo , Neoplasias/enzimologia , Neoplasias/genética , Neoplasias/patologia , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Resultado do Tratamento , Proteínas ras/genética , Proteínas ras/metabolismo
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