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1.
Gastroenterology ; 157(5): 1413-1428.e11, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31352001

RESUMO

BACKGROUND & AIMS: Obesity is a risk factor for pancreatic cancer. In mice, a high-fat diet (HFD) and expression of oncogenic KRAS lead to development of invasive pancreatic ductal adenocarcinoma (PDAC) by unknown mechanisms. We investigated how oncogenic KRAS regulates the expression of fibroblast growth factor 21, FGF21, a metabolic regulator that prevents obesity, and the effects of recombinant human FGF21 (rhFGF21) on pancreatic tumorigenesis. METHODS: We performed immunohistochemical analyses of FGF21 levels in human pancreatic tissue arrays, comprising 59 PDAC specimens and 45 nontumor tissues. We also studied mice with tamoxifen-inducible expression of oncogenic KRAS in acinar cells (KrasG12D/+ mice) and fElasCreERT mice (controls). KrasG12D/+ mice were placed on an HFD or regular chow diet (control) and given injections of rhFGF21 or vehicle; pancreata were collected and analyzed by histology, immunoblots, quantitative polymerase chain reaction, and immunohistochemistry. We measured markers of inflammation in the pancreas, liver, and adipose tissue. Activity of RAS was measured based on the amount of bound guanosine triphosphate. RESULTS: Pancreatic tissues of mice expressed high levels of FGF21 compared with liver tissues. FGF21 and its receptor proteins were expressed by acinar cells. Acinar cells that expressed KrasG12D/+ had significantly lower expression of Fgf21 messenger RNA compared with acinar cells from control mice, partly due to down-regulation of PPARG expression-a transcription factor that activates Fgf21 transcription. Pancreata from KrasG12D/+ mice on a control diet and given injections of rhFGF21 had reduced pancreatic inflammation, infiltration by immune cells, and acinar-to-ductal metaplasia compared with mice given injections of vehicle. HFD-fed KrasG12D/+ mice given injections of vehicle accumulated abdominal fat, developed extensive inflammation, pancreatic cysts, and high-grade pancreatic intraepithelial neoplasias (PanINs); half the mice developed PDAC with liver metastases. HFD-fed KrasG12D/+ mice given injections of rhFGF21 had reduced accumulation of abdominal fat and pancreatic triglycerides, fewer pancreatic cysts, reduced systemic and pancreatic markers of inflammation, fewer PanINs, and longer survival-only approximately 12% of the mice developed PDACs, and none of the mice had metastases. Pancreata from HFD-fed KrasG12D/+ mice given injections of rhFGF21 had lower levels of active RAS than from mice given vehicle. CONCLUSIONS: Normal acinar cells from mice and humans express high levels of FGF21. In mice, acinar expression of oncogenic KRAS significantly reduces FGF21 expression. When these mice are placed on an HFD, they develop extensive inflammation, pancreatic cysts, PanINs, and PDACs, which are reduced by injection of FGF21. FGF21 also reduces the guanosine triphosphate binding capacity of RAS. FGF21 might be used in the prevention or treatment of pancreatic cancer.


Assuntos
Células Acinares/metabolismo , Carcinoma Ductal Pancreático/metabolismo , Transformação Celular Neoplásica/metabolismo , Dieta Hiperlipídica , Fatores de Crescimento de Fibroblastos/metabolismo , Neoplasias Intraductais Pancreáticas/metabolismo , Neoplasias Pancreáticas/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Células Acinares/patologia , Animais , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/patologia , Carcinoma Ductal Pancreático/prevenção & controle , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/patologia , Regulação para Baixo , Fatores de Crescimento de Fibroblastos/genética , Regulação Neoplásica da Expressão Gênica , Humanos , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos Transgênicos , Mutação , PPAR gama/genética , PPAR gama/metabolismo , Cisto Pancreático/genética , Cisto Pancreático/metabolismo , Cisto Pancreático/patologia , Neoplasias Intraductais Pancreáticas/genética , Neoplasias Intraductais Pancreáticas/patologia , Neoplasias Intraductais Pancreáticas/prevenção & controle , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patologia , Neoplasias Pancreáticas/prevenção & controle , Pancreatite/genética , Pancreatite/metabolismo , Pancreatite/patologia , Proteínas Proto-Oncogênicas p21(ras)/genética , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/metabolismo , Transdução de Sinais , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo
2.
Cell Commun Signal ; 17(1): 19, 2019 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-30819189

RESUMO

Oncogenic KRAS plays a vital role in controlling tumor metabolism by enhancing aerobic glycolysis. Obesity driven by chronic consumption of high-fat diet (HFD) is a major risk factor for oncogenic KRAS-mediated pancreatic ductal adenocarcinoma (PDAC). However, the role of HFD in KRAS-mediated metabolic reprogramming has been obscure. Here, by using genetically engineered mouse models expressing an endogenous level of KRASG12D in pancreatic acinar cells, we demonstrate that hyperactivation of KRASG12D by obesogenic HFD, as compared to carbohydrate-rich diet, is responsible for enhanced aerobic glycolysis that associates with critical pathogenic responses in the path towards PDAC. Ablation of Cox-2 attenuates KRAS hyperactivation leading to the reversal of both aggravated aerobic glycolysis and high-grade dysplasia under HFD challenge. Our data highlight a pivotal role of the cooperative interaction between obesity-ensuing HFD and oncogenic KRAS in driving the heightened aerobic glycolysis during pancreatic tumorigenesis and suggest that in addition to directly targeting KRAS and aerobic glycolysis pathway, strategies to target the upstream of KRAS hyperactivation may bear important therapeutic value.


Assuntos
Dieta Hiperlipídica , Glicólise , Obesidade/metabolismo , Oncogenes , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Aerobiose , Animais , Ciclo-Oxigenase 2/metabolismo , Carboidratos da Dieta , Camundongos , Modelos Biológicos , Obesidade/patologia , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia
3.
Trends Pharmacol Sci ; 40(2): 142-153, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30616873

RESUMO

Endocrine fibroblast growth factors (eFGFs) control pathways that are crucial for maintaining metabolic homeostasis of lipids, glucose, energy, bile acids, and minerals. Unlike the heparin-binding paracrine FGFs, eFGFs require a unique Klotho family protein to form a productive triad complex, but the structural and mechanistical details of this complex have remained obscure since the beginning of the eFGF field. However, recent breakthroughs in resolving the 3D structures of eFGF signaling complexes have now unveiled the atomic details of multivalent interactions among eFGF, FGFR, and Klotho. We provide here a timely review on the architecture and the structure-function relationships of these complexes, and highlight how the structural knowledge opens a new door to structure-based drug design against a repertoire of eFGF-associated metabolic diseases.


Assuntos
Fatores de Crescimento de Fibroblastos/química , Fatores de Crescimento de Fibroblastos/metabolismo , Doenças Metabólicas/tratamento farmacológico , Doenças Metabólicas/metabolismo , Animais , Desenho de Drogas , Sistema Endócrino/metabolismo , Glucuronidase/química , Glucuronidase/metabolismo , Humanos , Receptores de Fatores de Crescimento de Fibroblastos/química , Receptores de Fatores de Crescimento de Fibroblastos/metabolismo , Relação Estrutura-Atividade
4.
Methods Mol Biol ; 1882: 207-219, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30378057

RESUMO

Pancreatic cancer is a highly lethal disease and is projected to become the second leading cause of cancer-related death by 2020. Among the different subtypes, pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer. The genetic landscape of PDAC shows nearly ubiquitous mutations of KRAS. However, expression of KRAS somatic mutants alone is insufficient to drive PDAC. Redox deregulation may contribute significantly to KRAS-mediated PDAC. Thus, measurement of cellular reactive oxygen species (ROS) levels is essential to determine how oxidative stress affects mutant KRAS and modulates intracellular signaling pathways leading to the change of cellular functions and the development of PDAC. Here we describe the protocol for comparative measurement of several key forms of ROS, including intracellular and mitochondrial levels of superoxide as well as extracellular H2O2 and general cellular ROS, with oxidation-sensitive fluorescent probes using flow cytometry in pancreatic cancer cells or mutant KRAS transformed cells.


Assuntos
Carcinoma Ductal Pancreático/patologia , Citometria de Fluxo/métodos , Neoplasias Pancreáticas/patologia , Espécies Reativas de Oxigênio/análise , Carcinoma Ductal Pancreático/genética , Técnicas de Cultura de Células/instrumentação , Técnicas de Cultura de Células/métodos , Linhagem Celular Tumoral , Citometria de Fluxo/instrumentação , Corantes Fluorescentes/química , Humanos , Mitocôndrias/patologia , Mutação , Estresse Oxidativo/genética , Pâncreas/patologia , Neoplasias Pancreáticas/genética , Proteínas Proto-Oncogênicas p21(ras)/genética , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/genética
5.
Trends Biochem Sci ; 43(8): 563-566, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29895507

RESUMO

Metabolic homeostasis is critical to cellular and organismal health. The newly revealed crystal structures of the endocrine factors FGF21 and FGF23, in association with the glycosidase coreceptor Klotho and transmembrane tyrosine kinase FGFR, set a platform for structure-based novel drug design against common metabolic disorders.


Assuntos
Doenças Metabólicas , Transdução de Sinais , Comunicação Celular , Homeostase , Humanos
8.
Cytokine Growth Factor Rev ; 38: 59-65, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28887067

RESUMO

FGF21 is a master regulator of homeostasis of local and systemic lipid, glucose and energy metabolism. Since its discovery a decade ago, significant progress has been made in understanding the basic molecular, cellular and physiological mechanisms underlying its metabolic roles, and characterizing its beneficial pharmacological activities and possible pathological roles in obesity, diabetes, dyslipidemia, fatty liver disease and their collateral complications and tissue damage. Under basal or normal conditions, FGF21 appears to play a dispensable role in metabolism. However, in response to a variety of cellular and metabolic stress, FGF21 is significantly upregulated to serve as a potent catabolic factor leading to the clearance of excessive lipids and glucose, and therefore, antagonizes metabolic and energy imbalance in a negative fashion. Furthermore, FGF21 treatment ameliorates tissue damage resulted from the harmful effects of metabolic abnormalities, which often ensue an oxidative, pro-inflammatory, inflammatory and/or immune stress state, the so-called metaflammation. Most notably, studies focusing on the liver, pancreas, cardio-vasculature and kidney have revealed its significant protective effects against the structural and functional damages induced by the obese, diabetic or other abnormal metabolic conditions. In this review, we will summarize the current progress on the roles of FGF21 against metaflammation and metabolic tissue damage.


Assuntos
Fatores de Crescimento de Fibroblastos/metabolismo , Estresse Fisiológico/fisiologia , Animais , Humanos , Inflamação/metabolismo , Doenças Metabólicas/metabolismo
9.
Endocrinology ; 157(12): 4754-4769, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27690692

RESUMO

The antiobese and antidiabetic fibroblast growth factor 21 (FGF21) regulates lipid metabolism and energy homeostasis by targeting the ßKlotho-FGFR1 (fibroblast growth factor receptor 1) binary complex in adipose tissue adipocytes. Because lipid droplet is the organelle responsible for storing lipid energy in adipocytes, it is the plausible target of FGF21 action. However, the impact of the FGF21-ßKlotho-FGFR1 signaling pathway on the functions of the lipid droplet is not clearly understood. Using our mouse models of adipocyte-specific FGFR1 ablation and hepatic overexpression of FGF21 with diet-induced obesity established previously, we analyzed the alterations of the pathways involved in energy and substrate metabolism that is attributable to the dynamic functions of the lipid droplet. In addition to the previous reports showing that FGFR1 deficiency abrogated lipolysis, fatty acid oxidation, and energy expenditure promoted by the elevated FGF21 signal, we observed that the deficiency up-regulated the biosynthesis and remodeling of membrane phospholipids that are important for the biogenesis and expansion of the droplet, whereas the enhanced FGF21 signal constrained the biosynthesis of phospholipids. As a result, the loss of adipose FGFR1 led to a sustained droplet expansion and endoplasmic reticulum (ER) stress, whereas the enhanced FGF21 signal suppressed them in obesogenesis. These new findings reveal that the FGF21-ßKlotho-FGFR1 signaling axis plays roles in maintaining phospholipid homeostasis and the dynamic functions of the lipid droplet, whereas protecting against ER stress, and suggest a potential link of phospholipid biosynthesis, lipid droplet dynamics, ER stress, and energy homeostasis in adipose tissue coordinated by this signaling axis.


Assuntos
Estresse do Retículo Endoplasmático/fisiologia , Fatores de Crescimento de Fibroblastos/metabolismo , Homeostase/fisiologia , Gotículas Lipídicas/metabolismo , Obesidade/metabolismo , Fosfolipídeos/metabolismo , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/metabolismo , Adipócitos/metabolismo , Tecido Adiposo/metabolismo , Animais , Metabolismo Energético/fisiologia , Fatores de Crescimento de Fibroblastos/genética , Metabolismo dos Lipídeos/fisiologia , Fígado/metabolismo , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Knockout , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , Transdução de Sinais/fisiologia
10.
Curr Mol Med ; 14(6): 703-711, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25056539

RESUMO

In addition to being positively regulated by prandial activity, bile acid production is also negatively controlled by the endocrine fibroblast growth factor 19 (FGF19) or the mouse ortholog FGF15 from the ileum that represses hepatic cholesterol 7 α-hydroxylase (Cyp7a1) expression through activating FGF receptor four (FGFR4). However, how these two regulatory mechanisms interplay to control bile acid homeostasis in the body and the downstream pathways by which FGFR4 regulates Cyp7a1 expression are not fully understood. Here we report that hepatocyte FGFR substrate 2α (FRS2α), a scaffold protein essential for canonical FGFRs to activate the ERK and AKT pathways, was required for the regulation of bile acid production by the FGF15/19-FGFR4 signaling axis. This occurred through limiting the extent of increases in Cyp7a1 expression induced by prandial activity. Excess FGFR4 kinase activity reduced the amplitude of the increase whereas a lack of FGFR4 augmented the increase of Cyp7a1 expression in the liver. Ablation of Frs2α alleles in hepatocytes abrogated the regulation of Cyp7a1 expression by FGFR4. Together, the results demonstrate that FRS2α-mediated pathways are essential for the FGF15/FGF19-FGFR4 signaling axis to control bile acid homeostasis.


Assuntos
Ácidos e Sais Biliares/biossíntese , Fatores de Crescimento de Fibroblastos/metabolismo , Hepatócitos/metabolismo , Proteínas de Membrana/genética , Alelos , Animais , Peso Corporal , Colesterol 7-alfa-Hidroxilase/genética , Colesterol 7-alfa-Hidroxilase/metabolismo , Regulação da Expressão Gênica , Genótipo , Fígado/citologia , Fígado/metabolismo , Masculino , Proteínas de Membrana/deficiência , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Transgênicos , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos/metabolismo , Transdução de Sinais
11.
J Natl Cancer Inst ; 106(7)2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24957076

RESUMO

BACKGROUND: Obesity increases the risk of cancer death among postmenopausal women with estrogen receptor-positive (ER+) breast cancer, but the direct evidence for the mechanisms is lacking. The purpose of this study is to demonstrate direct evidence for the mechanisms mediating this epidemiologic phenomenon. METHODS: We analyzed transcriptomic profiles of pretreatment biopsies from a prospective cohort of 137 ER+ breast cancer patients. We generated transgenic (MMTV-TGFα;A (y) /a) and orthotopic/syngeneic (A (y) /a) obese mouse models to investigate the effect of obesity on tumorigenesis and tumor progression and to determine biological mechanisms using whole-genome transcriptome microarrays and protein analyses. We used a coculture system to examine the impact of adipocytes/adipokines on breast cancer cell proliferation. All statistical tests were two-sided. RESULTS: Functional transcriptomic analysis of patients revealed the association of obesity with 59 biological functional changes (P < .05) linked to cancer hallmarks. Gene enrichment analysis revealed enrichment of AKT-target genes (P = .04) and epithelial-mesenchymal transition genes (P = .03) in patients. Our obese mouse models demonstrated activation of the AKT/mTOR pathway in obesity-accelerated mammary tumor growth (3.7- to 7.0-fold; P < .001; n = 6-7 mice per group). Metformin or everolimus can suppress obesity-induced secretion of adipokines and breast tumor formation and growth (0.5-fold, P = .04; 0.3-fold, P < .001, respectively; n = 6-8 mice per group). The coculture model revealed that adipocyte-secreted adipokines (eg, TIMP-1) regulate adipocyte-induced breast cancer cell proliferation and invasion. Metformin suppress adipocyte-induced cell proliferation and adipocyte-secreted adipokines in vitro. CONCLUSIONS: Adipokine secretion and AKT/mTOR activation play important roles in obesity-accelerated breast cancer aggressiveness in addition to hyperinsulinemia, estrogen signaling, and inflammation. Metformin and everolimus have potential for therapeutic interventions of ER+ breast cancer patients with obesity.


Assuntos
Antineoplásicos/farmacologia , Biomarcadores Tumorais/metabolismo , Neoplasias da Mama/etiologia , Neoplasias da Mama/metabolismo , Metformina/farmacologia , Obesidade/complicações , Obesidade/metabolismo , Receptores Estrogênicos/metabolismo , Sirolimo/análogos & derivados , Transcriptoma , Adipócitos , Adipocinas/metabolismo , Idoso , Animais , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Neoplasias da Mama/mortalidade , Neoplasias da Mama/patologia , Proliferação de Células/efeitos dos fármacos , Modelos Animais de Doenças , Everolimo , Feminino , Humanos , Estimativa de Kaplan-Meier , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Obesidade/epidemiologia , Obesidade/genética , Pós-Menopausa , Estudos Prospectivos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Sirolimo/farmacologia , Serina-Treonina Quinases TOR/metabolismo
12.
Cancer Metab ; 1(1): 21, 2013 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-24279986

RESUMO

BACKGROUND: Endocrine FGF21 and FGF19 target adipocytes and hepatocytes through betaKlotho (KLB) and FGFR tyrosine kinases effecting glucose, lipid and energy metabolism. Both factors alleviate obesity and metabolic abnormalities which are contributing factors to breast tumor progression. Genomic manipulation of hepatic FGFR4 has uncovered roles of endocrine FGF signaling in both metabolic and cellular homeostasis. Here we determined whether systemic and microenvironmental metabolic alterations caused by the FGFR4 deficiency affect tumorigenesis in breast where FGFR4 is negligible. Breast tumors were induced in the bigenic mice with ablation of FGFR4 and overexpression of TGFα that activates Her2 in the ductal and lobular epithelium surrounded by adipocytes. Mammary tumorigenesis and alterations in systemic and breast microenvironmental metabolic parameters and regulatory pathways were analyzed. RESULTS: Ablation of FGFR4 had no effect on cellular homeostasis and Her2 activity of normal breast tissue. However, the absence of FGFR4 reduced TGFα-driven breast tumor incidence and progression and improved host survival. Notable increases in hepatic and serum FGF21, ileal FGF15/19, adiponectin and adipsin, and decreases in systemic Fetuin A, IGF-1, IGFBP-1, RBP4 and TIMP1 were observed. The ablation affected adipogenesis and secretory function of adipocytes as well as lipogenesis, glycolysis and energy homeostasis associated with the functions of mitochondria, ER and peroxisomes in the breast and tumor foci. Treatment with a chemical inhibitor of NAMPT involved in the pathways inhibited the growth and survival of breast tumor cells and tumor-initiating cell-containing spheres. The FGFR4 ablation also caused elevation of inflammatory factors in the breast. CONCLUSIONS: Although the primary role of FGFR4 in metabolism occurs in hepatocytes, its ablation results in a net inhibitory effect on mammary tumor progression. We suggest that the tumor-delaying effect of FGFR4 deficiency may be in large part due to elevated anti-obesogenic FGF21 that triggers tumor-suppressing signals from both peripheral and breast adipocytes. The predominant changes in metabolic pathways suggested roles of metabolic effects from both peripheral and breast adipocytes on metabolic reprogramming in breast epithelial cells that contribute to the suppression of tumor progression. These results provide new insights into the contribution of systemic and microenvironmental metabolic effects controlled by endocrine FGF signaling to breast carcinogenesis.

13.
BMC Gastroenterol ; 13: 67, 2013 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-23590285

RESUMO

BACKGROUND: FGF21 is a promising intervention therapy for metabolic diseases as fatty liver, obesity and diabetes. Recent results suggest that FGF21 is highly expressed in hepatocytes under metabolic stress caused by starvation, hepatosteatosis, obesity and diabetes. Hepatic FGF21 elicits metabolic benefits by targeting adipocytes of the peripheral adipose tissue through the transmembrane FGFR1-KLB complex. Ablation of adipose FGFR1 resulted in increased hepatosteatosis under starvation conditions and abrogation of the anti-obesogenic action of FGF21. These results indicate that FGF21 may be a stress responsive hepatokine that targets adipocytes and adipose tissue for alleviating the damaging effects of stress on the liver. However, it is unclear whether hepatic induction of FGF21 is limited to only metabolic stress, or to a more general hepatic stress resulting from liver pathogenesis and injury. METHODS: In this survey-based study, we examine the nature of hepatic FGF21 activation in liver tissues and tissue sections from several mouse liver disease models and human patients, by quantitative PCR, immunohistochemistry, protein chemistry, and reporter and CHIP assays. The liver diseases include genetic and chemical-induced HCC, liver injury and regeneration, cirrhosis, and other types of liver diseases. RESULTS: We found that mouse FGF21 is induced in response to chemical (DEN treatment) and genetic-induced hepatocarcinogenesis (disruptions in LKB1, p53, MST1/2, SAV1 and PTEN). It is also induced in response to loss of liver mass due to partial hepatectomy followed by regeneration. The induction of FGF21 expression is potentially under the control of stress responsive transcription factors p53 and STAT3. Serum FGF21 levels correlate with FGF21 expression in hepatocytes. In patients with hepatitis, fatty degeneration, cirrhosis and liver tumors, FGF21 levels in hepatocytes or phenotypically normal hepatocytes are invariably elevated compared to normal health subjects. CONCLUSION: FGF21 is an inducible hepatokine and could be a biomarker for normal hepatocyte function. Activation of its expression is a response of functional hepatocytes to a broad spectrum of pathological changes that impose both cellular and metabolic stress on the liver. Taken together with our recent data, we suggest that hepatic FGF21 is a general stress responsive factor that targets adipose tissue for normalizing local and systemic metabolic parameters while alleviating the overload and damaging effects imposed by the pathogenic stress on the liver. This study therefore provides a rationale for clinical biomarker studies in humans.


Assuntos
Carcinoma Hepatocelular/metabolismo , Transformação Celular Neoplásica/metabolismo , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Fatores de Crescimento de Fibroblastos/metabolismo , Cirrose Hepática/metabolismo , Neoplasias Hepáticas/metabolismo , Animais , Carcinoma Hepatocelular/induzido quimicamente , Transformação Celular Neoplásica/genética , Dietilnitrosamina , Modelos Animais de Doenças , Fatores de Crescimento de Fibroblastos/genética , Hepatócitos/metabolismo , Humanos , Fígado/metabolismo , Fígado/patologia , Fígado/cirurgia , Neoplasias Hepáticas/induzido quimicamente , Masculino , Proteínas de Membrana/genética , Camundongos , Proteínas Serina-Treonina Quinases/genética , RNA Mensageiro/metabolismo , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos/genética , Fator de Transcrição STAT3/metabolismo , Estresse Fisiológico , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo
14.
Front Endocrinol (Lausanne) ; 4: 194, 2013 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-24385972

RESUMO

Fibroblast growth factor 21 (FGF21) is an emerging regulator of local and systemic metabolic homeostasis. Treatment with pharmacological levels of FGF21 alleviates obesity and associated metabolic diseases including diabetes. However, beyond anti-obesogenic effects, the normal roles and underlying mechanisms of FGF21 as an endocrine hormone remain unclear. A recent wave of studies has revealed that FGF21 is a stress-induced endocrine factor in liver, muscle, and other tissues that targets adipose tissue and adipocytes through the FGFR1-betaKlotho complex. Adipose tissues and adipocytes within diverse tissues respond with metabolites and adipokine signals that affect functions of body tissues systemically and cells within the local microenvironment adjacent to adipocytes. Normally this is to prevent impaired tissue-specific function and damage to diverse tissues secreting FGF21 in response to chronic stress. Therefore, diverse stressed tissues and the adipose tissue and adipocytes constitute a beneficial endocrine and paracrine communication network through FGF21. Here we attempt to unify these developments with beneficial pharmacological effects of FGF21 on obesity in respect to inter-organ stress communication and mechanisms.

15.
Sci Transl Med ; 4(162): 162ra153, 2012 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-23197570

RESUMO

Fibroblast growth factor 21 (FGF21) is a distinctive member of the FGF family with potent beneficial effects on lipid, body weight, and glucose metabolism and has attracted considerable interest as a potential therapeutic for treating diabetes and obesity. As an alternative to native FGF21, we have developed a monoclonal antibody, mimAb1, that binds to ßKlotho with high affinity and specifically activates signaling from the ßKlotho/FGFR1c (FGF receptor 1c) receptor complex. In obese cynomolgus monkeys, injection of mimAb1 led to FGF21-like metabolic effects, including decreases in body weight, plasma insulin, triglycerides, and glucose during tolerance testing. Mice with adipose-selective FGFR1 knockout were refractory to FGF21-induced improvements in glucose metabolism and body weight. These results in obese monkeys (with mimAb1) and in FGFR1 knockout mice (with FGF21) demonstrated the essential role of FGFR1c in FGF21 function and suggest fat as a critical target tissue for the cytokine and antibody. Because mimAb1 depends on ßKlotho to activate FGFR1c, it is not expected to induce side effects caused by activating FGFR1c alone. The unexpected finding of an antibody that can activate FGF21-like signaling through cell surface receptors provided preclinical validation for an innovative therapeutic approach to diabetes and obesity.


Assuntos
Anticorpos Monoclonais/uso terapêutico , Diabetes Mellitus/tratamento farmacológico , Fatores de Crescimento de Fibroblastos/imunologia , Glucuronidase/metabolismo , Obesidade/tratamento farmacológico , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/metabolismo , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/metabolismo , Tecido Adiposo/patologia , Animais , Anticorpos Monoclonais/farmacologia , Peso Corporal/genética , Diabetes Mellitus/sangue , Epitopos/química , Glucose/metabolismo , Glucuronidase/imunologia , Humanos , Macaca fascicularis , Camundongos , Obesidade/sangue , Obesidade/complicações , Fosfatos/sangue , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/agonistas , Transdução de Sinais/efeitos dos fármacos , Triglicerídeos/sangue
16.
Nutr Metab (Lond) ; 9(1): 94, 2012 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-23106963

RESUMO

BACKGROUND: Endocrine FGF19 and FGF21 exert their effects on metabolic homeostasis through fibroblast growth factor receptor (FGFR) and co-factor betaKlotho (KLB). Ileal FGF19 regulates bile acid metabolism through specifically FGFR4-KLB in hepatocytes where FGFR1 is not significant. Both FGF19 and FGF21 activate FGFR1-KLB whose function predominates in adipocytes. Recent studies using administration of FGF19 and FGF21 and genetic ablation of KLB or adipocyte FGFR1 indicate that FGFR1-KLB mediates the response of adipocytes to both FGF21 and FGF19. Here we show that adipose FGFR1 regulates lipid metabolism through direct effect on adipose tissue and indirect effects on liver under starvation conditions that cause hepatic stress. METHODS: We employed adipocyte-specific ablations of FGFR1 and FGFR2 genes in mice, and analyzed metabolic consequences in adipose tissue, liver and systemic parameters under normal, fasting and starvation conditions. RESULTS: Under normal conditions, the ablation of adipose FGFR1 had little effect on adipocytes, but caused shifts in expression of hepatic genes involved in lipid metabolism. Starvation conditions precipitated a concurrent elevation of serum triglycerides and non-esterified fatty acids, and increased hepatic steatosis and adipose lipolysis in the FGFR1-deficient mice. Little effect on glucose or ketone bodies due to the FGFR1 deficiency was observed. CONCLUSIONS: Our results suggest an adipocyte-hepatocyte communication network mediated by adipocyte FGFR1 that concurrently dampens hepatic lipogenesis and adipocyte lipolysis. We propose that this serves overall to mete out and extend lipid reserves for neural fuels (glucose and ketone bodies), while at the same time governing extent of hepatosteatosis during metabolic extremes and other conditions causing hepatic stress.

17.
Protein Cell ; 3(12): 950-61, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23011846

RESUMO

Heparinase III (HepIII) is a 73-kDa polysaccharide lyase (PL) that degrades the heparan sulfate (HS) polysaccharides at sulfate-rare regions, which are important co-factors for a vast array of functional distinct proteins including the well-characterized antithrombin and the FGF/FGFR signal transduction system. It functions in cleaving metazoan heparan sulfate (HS) and providing carbon, nitrogen and sulfate sources for host microorganisms. It has long been used to deduce the structure of HS and heparin motifs; however, the structure of its own is unknown. Here we report the crystal structure of the HepIII from Bacteroides thetaiotaomicron at a resolution of 1.6 Å. The overall architecture of HepIII belongs to the (α/α)5 toroid subclass with an N-terminal toroid-like domain and a C-terminal ß-sandwich domain. Analysis of this high-resolution structure allows us to identify a potential HS substrate binding site in a tunnel between the two domains. A tetrasaccharide substrate bound model suggests an elimination mechanism in the HS degradation. Asn260 and His464 neutralize the carboxylic group, whereas Tyr314 serves both as a general base in C-5 proton abstraction, and a general acid in a proton donation to reconstitute the terminal hydroxyl group, respectively. The structure of HepIII and the proposed reaction model provide a molecular basis for its potential practical utilization and the mechanism of its eliminative degradation for HS polysaccarides.


Assuntos
Heparitina Sulfato/metabolismo , Polissacarídeo-Liase/química , Polissacarídeo-Liase/metabolismo , Sequência de Aminoácidos , Bacteroides/enzimologia , Domínio Catalítico , Cristalografia por Raios X , Cinética , Modelos Moleculares , Dados de Sequência Molecular , Especificidade por Substrato
18.
PLoS Biol ; 10(5): e1001326, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22589701

RESUMO

Elevated aerobic glycolysis in cancer cells (the Warburg effect) may be attributed to respiration injury or mitochondrial dysfunction, but the underlying mechanisms and therapeutic significance remain elusive. Here we report that induction of mitochondrial respiratory defect by tetracycline-controlled expression of a dominant negative form of DNA polymerase γ causes a metabolic shift from oxidative phosphorylation to glycolysis and increases ROS generation. We show that upregulation of NOX is critical to support the elevated glycolysis by providing additional NAD+. The upregulation of NOX is also consistently observed in cancer cells with compromised mitochondria due to the activation of oncogenic Ras or loss of p53, and in primary pancreatic cancer tissues. Suppression of NOX by chemical inhibition or genetic knockdown of gene expression selectively impacts cancer cells with mitochondrial dysfunction, leading to a decrease in cellular glycolysis, a loss of cell viability, and inhibition of cancer growth in vivo. Our study reveals a previously unrecognized function of NOX in cancer metabolism and suggests that NOX is a potential novel target for cancer treatment.


Assuntos
Glicólise , Mitocôndrias/patologia , NADPH Oxidases/metabolismo , Neoplasias Pancreáticas/enzimologia , Animais , Sobrevivência Celular , Ativação Enzimática , Técnicas de Silenciamento de Genes , Genes Neoplásicos , Células HEK293 , Humanos , Camundongos , Camundongos Nus , Mitocôndrias/enzimologia , Mitocôndrias/metabolismo , NADPH Oxidase 1 , NADPH Oxidases/genética , Fosforilação Oxidativa , Neoplasias Pancreáticas/patologia , Plasmídeos/genética , Plasmídeos/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , RNA Interferente Pequeno/uso terapêutico , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismo , Superóxido Dismutase-1 , Tetraciclina/farmacologia , Transfecção , Ensaios Antitumorais Modelo de Xenoenxerto
19.
PLoS One ; 7(3): e33870, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22442730

RESUMO

BACKGROUND: Recent studies suggest that betaKlotho (KLB) and endocrine FGF19 and FGF21 redirect FGFR signaling to regulation of metabolic homeostasis and suppression of obesity and diabetes. However, the identity of the predominant metabolic tissue in which a major FGFR-KLB resides that critically mediates the differential actions and metabolism effects of FGF19 and FGF21 remain unclear. METHODOLOGY/PRINCIPAL FINDINGS: We determined the receptor and tissue specificity of FGF21 in comparison to FGF19 by using direct, sensitive and quantitative binding kinetics, and downstream signal transduction and expression of early response gene upon administration of FGF19 and FGF21 in mice. We found that FGF21 binds FGFR1 with much higher affinity than FGFR4 in presence of KLB; while FGF19 binds both FGFR1 and FGFR4 in presence of KLB with comparable affinity. The interaction of FGF21 with FGFR4-KLB is very weak even at high concentration and could be negligible at physiological concentration. Both FGF19 and FGF21 but not FGF1 exhibit binding affinity to KLB. The binding of FGF1 is dependent on where FGFRs are present. Both FGF19 and FGF21 are unable to displace the FGF1 binding, and conversely FGF1 cannot displace FGF19 and FGF21 binding. These results indicate that KLB is an indispensable mediator for the binding of FGF19 and FGF21 to FGFRs that is not required for FGF1. Although FGF19 can predominantly activate the responses of the liver and to a less extent the adipose tissue, FGF21 can do so significantly only in the adipose tissue and adipocytes. Among several metabolic and endocrine tissues, the response of adipose tissue to FGF21 is predominant, and can be blunted by the ablation of KLB or FGFR1. CONCLUSIONS: Our results indicate that unlike FGF19, FGF21 is unable to bind FGFR4-KLB complex with affinity comparable to FGFR1-KLB, and therefore, at physiological concentration less likely to directly and significantly target the liver where FGFR4-KLB predominantly resides. However, both FGF21 and FGF19 have the potential to activate responses of primarily the adipose tissue where FGFR1-KLB resides.


Assuntos
Fatores de Crescimento de Fibroblastos/metabolismo , Proteínas de Membrana/metabolismo , Complexos Multiproteicos/metabolismo , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/metabolismo , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos/metabolismo , Tecido Adiposo , Animais , Linhagem Celular Tumoral , Diabetes Mellitus/genética , Diabetes Mellitus/metabolismo , Fatores de Crescimento de Fibroblastos/genética , Humanos , Proteínas de Membrana/genética , Camundongos , Camundongos Knockout , Complexos Multiproteicos/genética , Obesidade/genética , Obesidade/metabolismo , Ligação Proteica , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , Receptor Tipo 4 de Fator de Crescimento de Fibroblastos/genética
20.
Mol Metab ; 2(1): 31-7, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-24024127

RESUMO

FGF21 is a multifunctional metabolic regulator. The co-factor ßKlotho (KLB) allows FGF21 to signal via FGF receptors. Given the widespread nature of FGFR expression and KLB presence in several organs, it remains unclear which tissue/FGFR isoform determine FGF21 action. Here we show that deletion of FGFR1 in fat (FR1KO) leads to a complete ablation of FGF21 stimulated transcriptional activity in this tissue. Furthermore, FR1KO mice showed no FGF21-mediated lowering of plasma glucose, insulin and triglycerides, altered serum levels of adipokines, no increase in energy expenditure, but preserved reductions in serum/liver FFAs as compared to wild type mice. Of importance, the anti-glycaemic actions of FGF19 were fully evident in FR1KO mice implying that FGF19 functions in a FGFR1/adipose independent manner. Taken together, our findings reveal the existence of an adipose FGFR1 driven axis of cross-tissue communication which defines several aspects of FGF21 biology and delineates mechanistic distinctions between FGF21 and FGF19.

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