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Poster session 3Cell growth, differentiation and stem cells - Heart511The role of the endocannabinoid system in modelling muscular dystrophy cardiac disease with induced pluripotent stem cells.512An emerging role of T lymphocytes in cardiac regenerative processes in heart failure due to dilated cardiomyopathy513Canonical wnt signaling reverses the ‘aged/senescent’ human endogenous cardiac stem cell phenotype514Hippo signalling modulates survival of human induced pluripotent stem cell-derived cardiomyocytes515Biocompatibility of mesenchymal stem cells with a spider silk matrix and its potential use as scaffold for cardiac tissue regeneration516A snapshot of genome-wide transcription in human induced pluripotent stem cell-derived hepatocyte-like cells (iPSC-HLCs)517Can NOS/sGC/cGK1 pathway trigger the differentiation and maturation of mouse embryonic stem cells (ESCs)?518Introduction of external Ik1 to human-induced pluripotent stem cell-derived cardiomyocytes via Ik1-expressing HEK293519Cell therapy of the heart studied using adult myocardial slices in vitro520Enhancement of the paracrine potential of human adipose derived stem cells when cultured as spheroid bodies521Mechanosensitivity of cardiomyocyte progenitor cells: the strain response in 2D and 3D environments522The effect of the vascular-like network on the maturation of the human induced pluripotent stem cell derived cardiomyocytes.Transcriptional control and RNA species - Heart525Gene expression regulation in heart failure: from pathobiology to bioinformatics526Human transcriptome in idiopathic dilated cardiomyopathy - a novel high throughput screening527A high-throghput approach unveils putative miRNA-mediated mitochondria-targeted cardioprotective circuits activated by T3 in the post ischemia reperfusion setting528The effect of uraemia on the expression of miR-212/132 and the calcineurin pathway in the rat heartCytokines and cellular inflammation - Heart531Lack of growth differentiation factor 15 aggravates adverse cardiac remodeling upon pressure-overload in mice532Blocking heteromerization of platelet chemokines ccl5 and cxcl4 reduces inflammation and preserves heart function after myocardial infarction533Is there an association between low-dose aspirin use and clinical outcome in HFPEF? Implications of modulating monocyte function and inflammatory mediator release534N-terminal truncated intracellular matrix metalloproteinase-2 expression in diabetic heart.535Expression of CD39 and CD73 on peripheral T-cell subsets in calcific aortic stenosis536Mast cells in the atrial myocardium of patients with atrial fibrillation: a comparison with patients in sinus rhythm539Characteristics of the inflammatory response in patients with coronary artery disease and arterial hypertension540Pro-inflammatory cytokines as cardiovascular events predictors in rheumatoid arthritis and asymptomatic atherosclerosis541Characterization of FVB/N murinic bone marrow-derived macrophage polarization into M1 and M2 phenotypes542The biological expression and thoracic anterior pain syndromeSignal transduction - Heart545The association of heat shock protein 90 and TGFbeta receptor I is involved in collagen production during cardiac remodelling in aortic-banded mice546Loss of the inhibitory GalphaO protein in the rostral ventrolateral medulla of the brainstem leads to abnormalities in cardiovascular reflexes and altered ventricular excitablitiy547Selenoprotein P regulates pressure overload-induced cardiac remodeling548Study of adenylyl cyclase activity in erythrocyte membranes in patients with chronic heart failure549Direct thrombin inhibitors inhibit atrial myocardium hypertrophy in a rat model of heart failure and atrial remodeling550Tissue factor / FVIIa transactivates the IGF-1R by a Src-dependent phosphorylation of caveolin-1551Notch signaling is differently altered in endothelial and smooth muscle cells of ascending aortic aneurysm patients552Frizzled 5 expression is essential for endothelial proliferation and migration553Modulation of vascular function and ROS production by novel synthetic benzopyran analogues in diabetes mellitusExtracellular matrix and fibrosis - Heart556Cardiac fibroblasts as inflammatory supporter cells trigger cardiac inflammation in heart failure557A role for galectin-3 in calcific aortic valve stenosis558Omega-3 polyunsaturated fatty acids- can they decrease risk for ventricular fibrillation?559Serum levels of elastin derived peptides and circulating elastin-antielastin immune complexes in sera of patients with coronary artery disease560Endocardial fibroelastosis is secondary to hemodynamic alterations in the chick model of hypoplastic left heart syndrome561Dynamics of serum levels of matrix metalloproteinases in primary anterior STEMI patients564Deletion of the alpha-7 nicotinic acetylcholine receptor changes the vascular remodeling induced by transverse aortic constriction in mice.565Extracellular matrix remodelling in response to venous hypertension: proteomics of human varicose veinsIon channels, ion exchangers and cellular electrophysiology - Heart568Microtubule-associated protein RP/EB family member 1 modulates sodium channel trafficking and cardiac conduction569Investigation of electrophysiological abnormalities in a rabbit athlete's heart model570Upregulation of expression of multiple genes in the atrioventricular node of streptozotocin-induced diabetic rat571miR-1 as a regulator of sinoatrial rhythm in endurance training adaptation572Selective sodium-calcium exchanger inhibition reduces myocardial dysfunction associated with hypokalaemia and ventricular fibrillation573Effect of racemic and levo-methadone on action potential of human ventricular cardiomyocytes574Acute temperature effects on the chick embryonic heart functionVasculogenesis, angiogenesis and arteriogenesis577Clinical improvement and enhanced collateral vessel growth after monocyte transplantation in mice578The role of HIF-1 alpha, VEGF and obstructive sleep apnoea in the development of coronary collateral circulation579Initiating cardiac repair with a trans-coronary sinus catheter intervention in an ischemia/reperfusion porcine animal model580Early adaptation of pre-existing collaterals after acute arteriolar and venular microocclusion: an in vivo study in chick chorioallantoic membraneEndothelium583EDH-type responses to the activator of potassium KCa2.3 and KCa3.1 channels SKA-31 in the small mesenteric artery from spontaneously hypertensive rats584The peculiarities of endothelial dysfunction in patients with chronic renocardial syndrome585Endothelial dysfunction, atherosclerosis of the carotid arteries and level of leptin in patient with coronary heart disease in combination with hepatic steatosis depend from body mass index.586Role of non-coding RNAs in thoracic aortic aneurysm associated with bicuspid aortic valve587Cigarette smoke extract abrogates atheroprotective effects of high laminar flow on endothelial function588The prognostic value of anti-connective tissue antibodies in coronary heart disease and asymptomatic atherosclerosis589Novel potential properties of bioactive peptides from spanish dry-cured ham on the endothelium.Lipids592Intermediate density lipoprotein is associated with monocyte subset distribution in patients with stable atherosclerosis593The characteristics of dyslipidemia in rheumatoid arthritisAtherosclerosis596Macrophages differentiated in vitro are heterogeneous: morphological and functional profile in patients with coronary artery disease597Palmitoylethanolamide promotes anti-inflammatory phenotype of macrophages and attenuates plaque formation in ApoE-/- mice598Amiodarone versus esmolol in the perioperative period: an in vitro study of coronary artery bypass grafts599BMPRII signaling of fibrocytes, a mesenchymal progenitor cell population, is increased in STEMI and dyslipidemia600The characteristics of atherogenesis and systemic inflammation in rheumatoid arthritis601Role of adenosine-to-inosine RNA editing in human atherosclerosis602Presence of bacterial DNA in thrombus aspirates of patients with myocardial infarction603Novel E-selectin binding polymers reduce atherosclerotic lesions in ApoE(-/-) mice604Differential expression of the plasminogen receptor Plg-RKT in monocyte and macrophage subsets - possible functional consequences in atherogenesis605Apelin-13 treatment enhances the stability of atherosclerotic plaques606Mast cells are increased in the media of coronary lesions in patients with myocardial infarction and favor atherosclerotic plaque instability607Association of neutrophil to lymphocyte ratio with presence of isolated coronary artery ectasiaCalcium fluxes and excitation-contraction coupling610The coxsackie- and adenovirus receptor (CAR) regulates calcium homeostasis in the developing heart611HMW-AGEs application acutely reduces ICaL in adult cardiomyocytes612Measuring electrical conductibility of cardiac T-tubular systems613Postnatal development of cardiac excitation-contraction coupling in rats614Role of altered Ca2+ homeostasis during adverse cardiac remodeling after ischemia/reperfusion615Experimental study of sarcoplasmic reticulum dysfunction and energetic metabolism in failing myocardium associated with diabetes mellitusHibernation, stunning and preconditioning618Volatile anesthetic preconditioning attenuates ischemic-reperfusion injury in type II diabetic patients undergoing on-pump heart surgery619The effect of early and delayed phase of remote ischemic preconditioning on ischemia-reperfusion injury in the isolated hearts of healthy and diabetic rats620Post-conditioning with 1668-thioate leads to attenuation of the inflammatory response and remodeling with less fibrosis and better left ventricular function in a murine model of myocardial infarction621Maturation-related changes in response to ischemia-reperfusion injury and in effects of classical ischemic preconditioning and remote preconditioningMitochondria and energetics624Phase changes in myocardial mitochondrial respiration caused by hypoxic preconditioning or periodic hypoxic training625Desmin mutations depress mitochondrial metabolism626Methylene blue modulates mitochondrial function and monoamine oxidases-related ROS production in diabetic rat hearts627Doxorubicin modulates the real-time oxygen consumption rate of freshly isolated adult rat and human ventricular cardiomyocytesCardiomyopathies and fibrosis630Effects of genetic or pharmacologic inhibition of the ubiquitin/proteasome system on myocardial proteostasis and cardiac function631Suppression of Wnt signalling in a desmoglein-2 transgenic mouse model for arrhythmogenic cardiomyopathy632Cold-induced cardiac hypertrophy is reversed after thermo-neutral deacclimatization633CD45 is a sensitive marker to diagnose lymphocytic myocarditis in endomyocardial biopsies of living patients and in autopsies634Atrial epicardial adipose tissue derives from epicardial progenitors635Caloric restriction ameliorates cardiac function, sympathetic cardiac innervation and beta-adrenergic receptor signaling in an experimental model of post-ischemic heart failure636High fat diet improves cardiac remodelling and function after extensive myocardial infarction in mice637Epigenetic therapy reduces cardiac hypertrophy in murine models of heart failure638Imbalance of the VHL/HIF signaling in WT1+ Epicardial Progenitors results in coronary vascular defects, fibrosis and cardiac hypertrophy639Diastolic dysfunction is the first stage of the developing heart failure640Colchicine aggravates coxsackievirus B3 infection in miceArterial and pulmonary hypertension642Osteopontin as a marker of pulmonary hypertension in patients with coronary heart disease combined with chronic obstructive pulmonary disease643Myocardial dynamic stiffness is increased in experimental pulmonary hypertension partly due to incomplete relaxation644Hypotensive effect of quercetin is possibly mediated by down-regulation of immunotroteasome subunits in aorta of spontaneously hypertensive rats645Urocortin-2 improves right ventricular function and attenuates experimental pulmonary arterial hypertension646A preclinical evaluation of the anti-hypertensive properties of an aqueous extract of Agathosma (Buchu)Biomarkers648The adiponectin level in hypertensive females with rheumatoid arthritis and its relationship with subclinical atherosclerosis649Markers for identification of renal dysfunction in the patients with chronic heart failure650cardio-hepatic syndromes in chronic heart failure: North Africa profile651To study other biomarkers that assess during myocardial infarction652Interconnections of apelin levels with parameters of lipid metabolism in hypertension patients653Plasma proteomics in hypertension: prediction and follow-up of albuminuria during chronic renin-angiotensin system suppression654Soluble RAGE levels in plasma of patients with cerebrovascular events. Cardiovasc Res 2016. [DOI: 10.1093/cvr/cvw150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Proteomic screening identifies calreticulin as a miR-27a direct target repressing MHC class I cell surface exposure in colorectal cancer. Cell Death Dis 2016; 7:e2120. [PMID: 26913609 PMCID: PMC4849154 DOI: 10.1038/cddis.2016.28] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 12/22/2015] [Accepted: 01/05/2016] [Indexed: 02/01/2023]
Abstract
Impairment of the immune response and aberrant expression of microRNAs are emerging hallmarks of tumour initiation/progression, in addition to driver gene mutations and epigenetic modifications. We performed a preliminary survey of independent adenoma and colorectal cancer (CRC) miRnoma data sets and, among the most dysregulated miRNAs, we selected miR-27a and disclosed that it is already upregulated in adenoma and further increases during the evolution to adenocarcinoma. To identify novel genes and pathways regulated by this miRNA, we employed a differential 2DE-DIGE proteome analysis. We showed that miR-27a modulates a group of proteins involved in MHC class I cell surface exposure and, mechanistically, demonstrated that calreticulin is a miR-27a direct target responsible for most downstream effects in epistasis experiments. In vitro miR-27a affected cell proliferation and angiogenesis; mouse xenografts of human CRC cell lines expressing different miR-27a levels confirmed the protein variations and recapitulated the cell growth and apoptosis effects. In vivo miR-27a inversely correlated with MHC class I molecules and calreticulin expression, CD8+ T cells infiltration and cytotoxic activity (LAMP-1 exposure and perforin release). Tumours with high miR-27a, low calreticulin and CD8+ T cells' infiltration were associated with distant metastasis and poor prognosis. Our data demonstrate that miR-27a acts as an oncomiRNA, represses MHC class I expression through calreticulin downregulation and affects tumour progression. These results may pave the way for better diagnosis, patient stratification and novel therapeutic approaches.
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The miR-27a-calreticulin axis affects drug-induced immunogenic cell death in human colorectal cancer cells. Cell Death Dis 2016; 7:e2108. [PMID: 26913599 PMCID: PMC4849155 DOI: 10.1038/cddis.2016.29] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 01/05/2016] [Indexed: 12/29/2022]
Abstract
Immunogenic cell death (ICD) evoked by chemotherapeutic agents implies emission of selected damage-associated molecular patterns (DAMP) such as cell surface exposure of calreticulin, secretion of ATP and HMGB1. We sought to verify whether miR-27a is implicated in ICD, having demonstrated that it directly targets calreticulin. To this goal, we exposed colorectal cancer cell lines, genetically modified to express high or low miR-27a levels, to two bona fide ICD inducers (mitoxantrone and oxaliplatin). Low miR-27a-expressing cells displayed more ecto-calreticulin on the cell surface and increased ATP and HMGB1 secretion than high miR-27a-expressing ones in time-course experiments upon drug exposure. A calreticulin target protector counteracted the miR-27a effects while specific siRNAs mimicked them, confirming the results reported. In addition, miR-27a negatively influenced the PERK-mediated route and the late PI3K-dependent secretory step of the unfolded protein response to endoplasmic reticulum stress, suggesting that miR-27a modulates the entire ICD program. Interestingly, upon chemotherapeutic exposure, low miR-27a levels associated with an earlier and stronger induction of apoptosis and with morphological and molecular features of autophagy. Remarkably, in ex vivo setting, under the same chemotherapeutic induction, the conditioned media from high miR-27a-expressing cells impeded dendritic cell maturation while increased the secretion of specific cytokines (interleukin (IL)-4, IL-6, IL-8) and negatively influenced CD4+ T-cell interferon γ production and proliferation, all markers of a tumor immunoevasion strategy. In conclusion, we provide the first evidence that miR-27a impairs the cell response to drug-induced ICD through the regulatory axis with calreticulin.
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A specific DNA methylation profile correlates with a high risk of disease progression in stage I classical (Alibert-Bazin type) mycosis fungoides. Br J Dermatol 2014; 170:1266-75. [PMID: 24641245 DOI: 10.1111/bjd.12717] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/29/2013] [Indexed: 12/14/2022]
Abstract
BACKGROUND Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma; in its classical presentation it evolves slowly, but it can have an aggressive course in a subset of patients. OBJECTIVES To investigate the impact of epigenetic mechanisms on the progression of early stage MF. METHODS We analysed DNA methylation at 12 different loci and long interspersed nucleotide elements-1 (LINE-1), as a surrogate marker of global methylation, on tissue samples from 41 patients with stage I MF followed up for at least 12 years or until disease progression. The methylation profiles were also analysed in two T-cell lymphoma cell lines and correlated with gene expression. RESULTS The selected loci were methylated in a tumour-specific manner; concomitant hypermethylation of at least four loci was more frequent in cases progressing within 1-3 and 3-6 years than in late-progressive or non-progressive cases. LINE-1 methylation was significantly lower in rapidly progressive MF at 3 years (61%, P < 0·001) than in those at 12 years (67%). PPARG, SOCS1 and NEUROG1 methylation showed remarkable differences among the prognostic groups, but only PPARG was a significant predictor of disease progression within 6 years, after adjustment for patients' age or gender. Strikingly, a methylation profile similar to progressive cases was found in highly proliferative Sézary-derived HUT78 cells but not in MF-derived HUT102 cells. Exposure to a DNA demethylating agent restored sensitivity to apoptosis and cell cycle arrest. CONCLUSIONS Epigenetic silencing of specific biomarkers can predict the risk of disease progression in early-stage MF, providing insights into its pathogenesis, prognosis and therapy.
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Impact of long-acting octreotide in patients with early-stage MEN1-related duodeno-pancreatic neuroendocrine tumours. Clin Endocrinol (Oxf) 2014; 80:850-5. [PMID: 24443791 DOI: 10.1111/cen.12411] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 12/22/2013] [Accepted: 01/13/2014] [Indexed: 01/07/2023]
Abstract
BACKGROUND Somatostatin analogues (SSA) represent one of the main therapeutic option in patients affected with functioning well-differentiated neuroendocrine tumours (NETs). There are no studies specifically focusing on NETs associated with Multiple Endocrine Neoplasia type 1 (MEN1). AIM To evaluate the efficacy of the long-acting SSA octreotide in MEN1 patients with early-stage duodeno-pancreatic NETs. PATIENTS AND METHODS Forty patients with MEN1 were retrospectively evaluated. Twenty patients with evidence of one or more MEN1-related duodeno-pancreatic NETs < 20 mm in size (age range 26-61 years) were treated with octreotide long-acting octreotide (LAR) as first-line therapy. Treatment duration ranged 12-75 months. At the baseline radiological evaluation, multiple duodeno-pancreatic NETs (range 1-8, size 3-18 mm) were detected. RESULTS An objective tumour response was observed in 10%, stable disease in 80% and progression of disease in 10% of cases. In six patients with abnormally increased CgA, gastrin and/or insulin serum concentrations, a significant clinical and hormonal response occurred in 100% of cases and was stable along the time. CONCLUSIONS Therapy with SSA is highly safe and effective in patients with early-stage MEN1 duodeno-pancreatic NETs, resulting in long-time suppression of tumour and hormonal activity and 10% objective response. This suggests to early start therapy with SSA in patients with MEN1-related NETs.
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Multiple endocrine neoplasia, the old and the new: a mini review. G Chir 2012; 33:370-373. [PMID: 23140918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Multiple endocrine neoplasia syndromes have since been classified as types 1 and 2, each with specific phenotypic patterns. MEN1 is usually associated with pituitary, parathyroid and paraneoplastic neuroendocrine tumours. The hallmark of MEN2 is a very high lifetime risk of developing medullary thyroid carcinoma (MTC) more than 95% in untreated patients. Three clinical subtypesdMEN2A, MEN2B, and familial MTC (FMTC) have been defined based on the risk of pheochromocytoma, hyperparathyroidism, and the presence or absence of characteristic physical features). MEN2 occurs as a result of germline activating missense mutations of the RET (REarranged during Transfection) proto-oncogene. MEN2-associated mutations are almost always located in exons 10, 11, or 13 through 16. Strong genotype-phenotype correlations exist with respect to clinical subtype, age at onset, and aggressiveness of MTC in MEN2. These are used to determine the age at which prophylactic thyroidectomy should occur and whether screening for pheochromocytoma or hyperparathyroidism is necessary. Specific RET mutations can also impact management in patients presenting with apparently sporadic MTC. Therefore, genetic testing should be performed before surgical intervention in all patients diagnosed with MTC. Recently, Pellegata et al. have reported that germline mutations in CDKN1B can predispose to the development of multiple endocrine tumours in both rats and humans and this new MEN syndrome is named MENX and MEN4, respectively. CDKN1B. A recent report showed that in sporadic MTC, CDKN1B V109G polymorphism correlates with a more favorable disease progression than the wild-type allele and might be considered a new promising prognostic marker. New insights on MEN syndrome pathogenesis and related inherited endocrine disorders are of particular interest for an adequate surgical and therapeutic approach.
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UHRF1 coordinates peroxisome proliferator activated receptor gamma (PPARG) epigenetic silencing and mediates colorectal cancer progression. Oncogene 2012; 31:5061-72. [PMID: 22286757 DOI: 10.1038/onc.2012.3] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Peroxisome proliferator-activated receptor gamma (PPARG) inactivation has been identified as an important step in colorectal cancer (CRC) progression, although the events involved have been partially clarified. UHRF1 is emerging as a cofactor that coordinates the epigenetic silencing of tumor suppressor genes, but its role in CRC remains elusive. Here, we report that UHRF1 negatively regulates PPARG and is associated with a higher proliferative, clonogenic and migration potential. Consistently, UHRF1 ectopic expression induces PPARG repression through its recruitment on the PPARG promoter fostering DNA methylation and histone repressive modifications. In agreement, UHRF1 knockdown elicits PPARG re-activation, accompanied by positive histone marks and DNA demethylation, corroborating its role in PPARG silencing. UHRF1 overexpression, as well as PPARG-silencing, imparts higher growth rate and phenotypic features resembling those occurring in the epithelial-mesenchymal transition. In our series of 110 sporadic CRCs, high UHRF1-expressing tumors are characterized by an undifferentiated phenotype, higher proliferation rate and poor clinical outcome only in advanced stages III-IV. In addition, the inverse relationship with PPARG found in vitro is detected in vivo and UHRF1 prognostic significance appears closely related to PPARG low expression, as remarkably validated in an independent dataset. The results demonstrate that UHRF1 regulates PPARG silencing and both genes appear to be part of a complex regulatory network. These findings suggest that the relationship between UHRF1 and PPARG may have a relevant role in CRC progression.
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The high expression of p53 in sporadic colorectal carcinoma is associated with metastasis and decreased survival. Pathologica 2010; 102:51-56. [PMID: 23596757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023] Open
Abstract
INTRODUCTION Alteration in the p53 tumour suppressor gene is an event that occurs frequently in human cancer, although its role as predictive and/or prognostic marker is still unclear. The aim of this study was to compare the expression profiles of p53 in colorectal carcinoma with clinicopathological features and survival rate at 5 years from diagnosis. METHODS One hundred and twenty cases of primary sporadic colorectal cancers (CRCs) and 80 matched normal mucosas were analyzed by immunohistochemistry on paraffin-embedded specimens. The correlation between protein expression profiles, clinicopathological parameters and survival was investigated. RESULTS In tumour tissues, the expression of p53 was high in 41 cases, low in 38 and negative in 41. A significant correlation was observed between increased p53 expression presence of lymph node (p = 0.002) or liver metastasis (p = 0.008). Moreover, higher levels of p53 were related with advanced tumour stage (III-IV; p = 0.007), poor survival and disease recurrence (p < 0.01). Interestingly, in multivariate analysis p53 expression and distant metastasis were independent prognostic markers. DISCUSSION Our results suggest that nuclear p53 accumulation in sporadic CRC may have prognostic significance and contribute to identification of patients at high risk of mortality. The current findings may be relevant for management of patients with CRC.
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A novel germline mutation in peroxisome proliferator-activated receptor gamma gene associated with large intestine polyp formation and dyslipidemia. Biochim Biophys Acta Mol Basis Dis 2010; 1802:572-81. [PMID: 20123124 DOI: 10.1016/j.bbadis.2010.01.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 01/07/2010] [Accepted: 01/19/2010] [Indexed: 12/31/2022]
Abstract
We report a novel PPARG germline mutation in a patient affected by colorectal cancer that replaces serine 289 with cysteine in the mature protein (S289C). The mutant has impaired transactivation potential and acts as dominant negative to the wild type receptor. In addition, it no longer restrains cell proliferation both in vitro and in vivo. Interestingly, the S289C mutant poorly activates target genes and interferes with the inflammatory pathway in tumor tissues and proximal normal mucosa. Consistently, only mutation carriers exhibit colonic lesions that can evolve to dysplastic polyps. The proband presented also dyslipidemia, hypertension and overweight, not associated to type 2 diabetes; of note, family members tested positive for the mutation and display only a dyslipidemic profile at variable penetrance with other biochemical parameters in the normal range. Finally, superimposing the mutation to the crystal structure of the ligand binding domain, the new Cys289 becomes so closely positioned to Cys285 to form an S-S bridge. This would reduce the depth of the ligand binding pocket and impede agonist positioning, explaining the biological effects and subcellular distribution of the mutant protein. This is the first PPARG germline mutation associated with dyslipidemia and colonic polyp formation that can progress to full-blown adenocarcinoma.
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Genetic prenatal RET testing and pregnancy management of multiple endocrine neoplasia Type II A (MEN2A): a case report. J Endocrinol Invest 2004; 27:357-60. [PMID: 15233556 DOI: 10.1007/bf03351062] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Multiple endocrine neoplasia 2A (MEN 2A) is an inherited dominant syndrome characterised by medullary thyroid carcinoma, adrenal pheochromocytoma and hyperparathyroidism due to specific RET proto-oncogene mutations. Fertile MEN 2A women are at risk of complicated pregnancy because of unrecognised pheochromocytoma and transmission of RET mutation to the progeny. This condition may cause psychological distress in affected pregnant patients and their families. Here we describe the genetic prenatal testing, the pregnancy management and obstetric outcome in a MEN 2A patient with a right side adrenal hyperplasia and elevated calcitonin levels, a condition suspicious for possible recurrence of pheochromocytoma. We confirm that maternal or fetal complications are rare when MEN 2A diagnosis is made before pregnancy and an accurate monitoring is instituted. Furthermore, our results indicate that prenatal testing for RET mutations is highly recommended in making decisions and assuring parents on the lifelong risk of tumors. This will avoid the psychological distress that can further complicate the pregnancy of affected women.
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Fasting plasma free fatty acid concentrations and Pro12Ala polymorphism of the peroxisome proliferator-activated receptor (PPAR) gamma2 gene in healthy individuals. Clin Endocrinol (Oxf) 2002; 57:481-6. [PMID: 12354130 DOI: 10.1046/j.1365-2265.2002.01618.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND The Pro12Ala polymorphism of the peroxisome proliferator-activated receptor (PPAR) gamma gene has been associated in some, but not all, studies with lower body mass index (BMI) and improved insulin sensitivity; how an altered transcriptional activity of PPARgamma2 could influence insulin sensitivity is currently unclear. The free fatty acids (FFAs) released from adipose tissue triglycerides via lipolysis are key mediators of impaired insulin sensitivity; however, no study has described the relationship of the Pro12Ala mutation with circulating levels of FFAs under physiological conditions. OBJECTIVE To investigate in a population-based sample of Caucasians the relation of the Pro12Ala polymorphism with plasma concentrations of FFAs and other markers of lipid and glucose metabolism described as components of the insulin resistance syndrome. SUBJECTS Four hundred and thirty-eight nondiabetic employees of the Italian Telephone Company, aged 35-65 years, randomly selected from a total population of 3900 participants in a company-sponsored health screening. MEASUREMENTS The Pro12Ala polymorphism of the PPARgamma was studied together with plasma FFAs, insulin, glucose, triglycerides, high density lipoprotein (HDL) cholesterol, blood pressure and anthropometry. The Homeostatic Model Assessment (HOMA) index was calculated as a measure of insulin resistance. RESULTS Carriers and noncarriers of the Pro12Ala polymorphism showed very similar circulating levels of FFA (0.46 +/- 0.2 vs. 0.47 +/- 0.2, NS); plasma glucose, triglycerides, HDL cholesterol and blood pressure were also similar in the two groups with or without the polymorphism. To allow for the possible confounding effect of obesity, a separate analysis was conducted in overweight (BMI > or = 25 kg/m(2)) and normal-weight people (BMI < 25 kg/m(2)). Circulating plasma FFA concentrations, as well as triglycerides, blood pressure and HOMA, were significantly higher in overweight than normal-weight, as expected, but no significant differences were detected between carriers and noncarriers of the Pro12Ala polymorphism within each BMI group (0.49 +/- 0.2 vs. 0.48 +/- 0.2, NS, and 0.44 +/- 0.2 vs. 0.47 +/- 0.2, NS, in overweight and normal-weight, respectively). The Pro12Ala polymorphism was also analysed across increasing quartiles of FFA concentrations and no relationship was observed between the frequency of the polymorphism and FFA values (overall chi2 = 0.48, NS). CONCLUSION This study does not show any relationship between the Pro12Ala polymorphism of the PPARgamma gene and fasting FFAs in the general population. The possibility of a different handling of FFAs under different conditions (i.e. postprandial) cannot be excluded and remains to be explored.
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Medullary thyroid cancer, papillary thyroid microcarcinoma and Graves' disease: an unusual clinical coexistence. J Endocrinol Invest 2001; 24:892-6. [PMID: 11817715 DOI: 10.1007/bf03343948] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
We describe the unusual case of a Caucasian woman who had a diagnosis of medullary thyroid cancer and papillary microcarcinoma 5 years after a diagnosis of Graves' disease. The patient came to our observation for recurrence of hyperthyroidism. An ultrasound scan revealed diffuse thyroid enlargement with a nodule, recently increased in size. The serum CT and carcinoembrional antigen were elevated, and the fine-needle aspiration cytology with immunocytochemical analysis for CT was suggestive for medullary thyroid carcinoma. The nodular lesion showed intense 111In-pentetreotide uptake, whereas total body scintigraphy with the same tracer and with Thallium-201, 99mTc (V) dimercaptosuccinic acid was negative for lymph node and distant metastasis. The histological examination of thyroidectomy specimens confirmed the diagnosis of medullary thyroid cancer, showing a lymphocytic intratumoral infiltration. The histological analysis of the controlateral lobe showed an occult papillary microcarcinoma. Medullary thyroid carcinoma and papillary microcarcinoma showed intense staining with policlonal anti-RET antibodies, although genetic analysis was negative for RET mutations most frequently involved in familial and sporadic medullary thyroid carcinomas. Possible implications about the coexistence of the 3 thyroid diseases are discussed.
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Retinol mobilization from cultured rat hepatic stellate cells does not require retinol binding protein synthesis and secretion. Int J Biochem Cell Biol 2001; 33:1000-12. [PMID: 11470233 DOI: 10.1016/s1357-2725(01)00066-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Retinol mobilization from retinyl esters stores of hepatic stellate cells (HSCs) is a key step in the regulation of mammalian retinol homeostasis, but the precise mechanisms of such a mobilization are still poorly understood. Using primary cultures of HSCs, we first demonstrated that HSCs expressed immunoreactivity against retinol-binding-protein (RBP) when cultured in a medium containing RBP but were unable to synthesize RBP transcripts and proteins. Using pulse and chase-type experiments, we demonstrated that radioactive retinol was released in culture medium without binding proteins. Inhibition of protein secretion by brefeldin A did not modify quantitatively retinol release. This data ruled out, for the first time, the direct involvement of RBP in retinol mobilization from HSCs. Moreover, HSCs co-cultured with primary isolated hepatocytes displayed an increase of retinol transfer from HSCs to hepatocytes when they established direct physical contacts, as compared with co-cultures without contact. Based on this latter data, a mechanism of retinol mobilization from HSCs via the hepatocytes using retinol transfer through cellular membranes is proposed.
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Preservation of light signaling to the suprachiasmatic nucleus in vitamin A-deficient mice. Proc Natl Acad Sci U S A 2001; 98:11708-13. [PMID: 11562477 PMCID: PMC58794 DOI: 10.1073/pnas.201301498] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2001] [Indexed: 11/18/2022] Open
Abstract
To investigate the role of retinal-based pigments (opsins) in circadian photoreception in mice, animals mutated in plasma retinol binding protein were placed on a vitamin A-free diet and tested for photic induction of gene expression in the suprachiasmatic nucleus. After 10 months on the vitamin A-free diet, the majority of mice contained no detectable retinal in their eyes. These mice demonstrated fully intact photic signaling to the suprachiasmatic nucleus as measured by acute mPer mRNA induction in the suprachiasmatic nucleus in response to bright or dim light. The data suggest that a non-opsin pigment is the primary circadian photoreceptor in the mouse.
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15
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In vivo and in vitro studies of cytosolic phospholipase A2 expression in Helicobacter pylori infection. Infect Immun 2001; 69:5857-63. [PMID: 11500464 PMCID: PMC98704 DOI: 10.1128/iai.69.9.5857-5863.2001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2000] [Accepted: 06/11/2001] [Indexed: 02/07/2023] Open
Abstract
Modifications of mucosal phospholipids have been detected in samples from patients with Helicobacter pylori-positive gastritis. These alterations appear secondary to increased phospholipase A2 activity (PLA2). The cytosolic form of this enzyme (cPLA2), normally involved in cellular signaling and growth, has been implicated in cancer pathogenesis. The aim of this study was to investigate cPLA2 expression and PLA2 activity in the gastric mucosae of patients with and without H. pylori infection. In gastric biopsies from 10 H. pylori-positive patients, cPLA2 levels, levels of mRNA as determined by reverse transcriptase PCR, levels of protein as determined by immunohistochemistry, and total PLA2 activity were higher than in 10 H. pylori-negative gastritis patients. To clarify whether H. pylori had a direct effect on the cellular expression of cPLA2, we studied cPLA2 expression in vitro with different human epithelial cell lines, one from a patient with larynx carcinoma (i.e., HEp-2 cells) and two from patients with gastric adenocarcinoma (i.e., AGS and MKN 28 cells), incubated with different H. pylori strains. The levels of cPLA2, mRNA, and protein expression were unchanged in Hep-2 cells independently of cellular adhesion or invasion of the bacteria. Moreover, no change in cPLA2 protein expression was observed in AGS or MKN 28 cells treated with wild-type H. pylori. In conclusion, our study shows increased cPLA2 expression and PLA2 activity in the gastric mucosae of patients with H. pylori infection and no change in epithelial cell lines exposed to H. pylori.
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Abstract
Fibrates are hypolipidemic drugs that activate the peroxisome proliferator-activated receptors. Since fibrates may also increase energy expenditure, we investigated whether fenofibrate (FF) had this effect in diet-induced obese rats. A 2-month administration of a high-fat palatable diet to adult rats increased body weight by 25% and white adipose mass by 163% compared with a standard diet. These effects were prevented by FF, both when administered for the 2 months of high-fat feeding and when given for only the second month. Consequently, FF-treated rats had a final body weight and white adipose tissue mass similar to untreated animals on the standard diet. FF also increased resting metabolic rate, hepatic peroxisomal and mitochondrial palmitoyl-dependent oxygen uptake and mRNA levels of acyl-CoA oxidase and lipoprotein lipase. Finally, FF lowered mRNA levels of uncoupling protein-2 and did not affect mitochondrial respiration in skeletal muscle. Therefore, FF seems to act as a weight-stabilizer mainly through its effect on liver metabolism.
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Loss of heterozygosity at the RET protooncogene locus in a case of multiple endocrine neoplasia type 2A. J Clin Endocrinol Metab 2001; 86:239-44. [PMID: 11232007 DOI: 10.1210/jcem.86.1.7144] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We describe a patient affected by multiple endocrine neoplasia type 2A (MEN 2A) bearing a heterozygous germline mutation (Cys(634)Arg) in exon 11 and an additional somatic mutation of the RET protooncogene. A large intragenic deletion, spanning exon 4 to exon 16, affected the normal allele and was detected by quantitative PCR, Southern blot analysis, and screening of several polymorphic markers. This deletion causes RET loss of heterozygosity exclusively in the metastasis, thus suggesting a role for this second mutational event in tumor progression. No additional mutations were found in the other exons analyzed. We provide the first evidence that RET, a dominant oncogene, is affected by a germline mutation and by an additional somatic deletion of the wild-type allele. This unusual genetic profile may be related to the clinical course and very poor outcome.
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Retinol and retinol-binding protein: gut integrity and circulating immunoglobulins. J Infect Dis 2000; 182 Suppl 1:S97-S102. [PMID: 10944490 DOI: 10.1086/315920] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Vitamin A (retinol) is required to maintain immunity and epithelial turnover and is a key micronutrient needed for combating infection. Vitamin A actions on the immune system are diverse and cannot be accounted for by a single effect or mechanism. The actions of retinol in maintaining gut integrity in humans and immunoglobulin levels in mice was investigated. For 30 children, performance on the lactulose/mannitol test, a test commonly used to assess intestinal barrier function, was inversely correlated (P=.012) with serum retinol concentrations. Thus, children with lower serum retinol, and presumably poorer vitamin A nutritional status, are more likely to have impaired intestinal integrity. Knockout mice that have impairments in plasma retinol transport have circulating immunoglobulin levels that are half those observed in matched wild type mice. No differences were observed in B and T cell populations present in spleen, thymus, and bone marrow.
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Pro12Ala mutation in the peroxisome proliferator-activated receptor gamma2 (PPARgamma2) and severe obesity: a case-control study. Int J Obes (Lond) 2000; 24:1195-9. [PMID: 11033990 DOI: 10.1038/sj.ijo.0801366] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE To explore the association of the Pro12Ala mutation in the peroxisome proliferator-activated receptor gamma2 with severe obesity and the features of the metabolic syndrome in a population-based sample of Caucasians. PARTICIPANTS AND METHODS The study is based on a case-control design: 95 non-diabetic severely obese (body mass index, BMI > 35 kg/m2) cases and 280 normal weight (BMI < 25 kg/m2), age- and sex-matched controls selected from the same population were studied. Height, weight, waist circumference, as well as blood pressure were measured according to a standard protocol. BMI at age 25 y was calculated on the basis of current height and reported weight at age 25 y Biochemical measurements included fasting glucose, triglycerides, high-density lipoprotein cholesterol and insulin. DNA analysis was conducted by PCR and gel electrophoresis. RESULTS Age and gender distribution were similar in obese and normal weight participants. The percentage of people with the Pro12Ala mutation was not significantly different in obese or normal weight participants (20% and 15%, respectively; P = 0.32). Conversely, in obese participants with obesity starting in early adulthood (ie with BMI at age 25 above 26.9kg/m2 which represents the median of the whole obese group), the Pro12Ala mutation was observed significantly more frequently than in the normal weight controls (29% vs 15%; chi square = 4.5, P < 0.05; odds ratio 2.4; 95% CI 1.03-5.36). No association of the Pro12Ala variant with any of the component of the metabolic syndrome measured in the study was observed in either obese, juvenile obese or normal weight participants. CONCLUSIONS Results of this study indicate that the Pro12Ala mutation does not play a major role as a determinant of severe obesity and/or features of the metabolic syndrome in the general population. However, this mutation may be of greater importance as a contributor to early onset obesity.
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Abstract
Thyroid hormones influence the activity of lipogenic enzymes such as malic enzyme (ME) and glucose-6-phosphate dehydrogenase (G6PD). The effect of T3 on ME is exerted at the transcriptional level, but it is unclear if its effect on G6PD is also nuclear mediated. Furthermore, other iodothyronines that have been shown to possess biological activity (such as diiodothyronines) could contribute to this enzyme's regulation. In this study the effects of 3,5-diiodothyronine (T2) on the aforementioned enzymes were examined and compared with those of T3. Rats made hypothyroid by propylthiouracil and iopanoic acid treatment were used throughout. Enzyme activities were determined spectrophotometrically, and G6PD messenger RNA (mRNA) expression was analyzed by Northern blotting using a human G6PD complementary DNA probe. Injections of T2 to hypothyroid animals significantly enhanced the activity of both enzymes. The effect of T2 on ME was nuclear mediated and mimicked the effect of T3. The effects of T2 and T3 on G6PD differed. Injection of T3 into hypothyroid rats induced an increase in both enzyme activity and G6PD mRNA expression, indicating a nuclear-mediated effect. The effect of T2 on G6PD activity, on the other hand, was not nuclear mediated. The injection of T2 into hypothyroid animals did not change G6PD mRNA expression, and the strong increase in the enzyme's activity (from +70% to +300%) was unaffected by simultaneous injection of protein synthesis inhibitors. As the lowest dose of 1 microg T2/100 g BW affects G6PD activity 3-5 times more than the same dose of T3, these data provide the first evidence that T2 is a factor capable of regulating G6PD activity.
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A novel case of multiple endocrine neoplasia type 2A associated with two de novo mutations of the RET protooncogene. J Clin Endocrinol Metab 1999; 84:3522-7. [PMID: 10522989 DOI: 10.1210/jcem.84.10.6056] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We report a novel case of multiple endocrine neoplasia type 2A (MEN 2A) associated with two mutations of the protooncogene RET. One affects codon 634 and causes a cysteine to arginine substitution; the second at codon 640 causes an alanine to glycine substitution in the transmembrane region. The two mutations were present on the same RET allele and were detected in germline and tumor DNA. Both mutations were de novo, i.e. they were not found in the DNA of the parents or relatives. Immunohistochemical and RT-PCR analysis showed that the pheochromocytoma expressed calcitonin as well as both RET alleles. A cell line established from the tumor and propagated in culture sustained the expression of RET and calcitonin, as did the original pheochromocytoma. Because the patient presented with medullary thyroid carcinoma and pheochromocytoma without parathyroid gland involvement, we speculate that this clinical picture could be correlated with the two RET mutations and to the unusual calcitonin production. This is the first report of a MEN 2A case due to two mutations of the RET gene and associated with a calcitonin-producing pheochromocytoma.
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Abstract
Retinol-binding protein (RBP) is the sole specific transport protein for retinol (vitamin A) in the circulation, and its single known function is to deliver retinol to tissues. Within tissues, retinol is activated to retinoic acid, which binds to nuclear receptors to regulate transcription of >300 diverse target genes. In the eye, retinol is also activated to 11-cis-retinal, the visual chromophore. We generated RBP knockout mice (RBP(-/-)) by gene targeting. These mice have several phenotypes. Although viable and fertile, they have reduced blood retinol levels and markedly impaired retinal function during the first months of life. The impairment is not due to developmental retinal defect. Given a vitamin A-sufficient diet, the RBP(-/-) mice acquire normal vision by 5 months of age even though blood retinol levels remain low. Deprived of dietary vitamin A, vision remains abnormal and blood retinol declines to undetectable levels. Another striking phenotype of the mutant mice is their abnormal retinol metabolism. The RBP(-/-) mice can acquire hepatic retinol stores, but these cannot be mobilized. Thus, their vitamin A status is extremely tenuous and dependent on a regular vitamin A intake. Unlike wild-type mice, serum retinol levels in adult RBP(-/-) animals become undetectable after only a week on a vitamin A-deficient diet and their retinal function rapidly deteriorates. Thus RBP is needed for normal vision in young animals and for retinol mobilization in times of insufficient dietary intake, but is otherwise dispensable for the delivery of retinol to tissues.
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Abstract
Peroxisome proliferator-activated receptor (PPAR)-gamma is a major regulator of adipogenesis and insulin sensitivity. The PPAR-gamma gene generates two isoforms through alternative splicing, PPAR-gamma1 and -gamma2, the latter having an additional stretch of 28 amino acids at its NH2-terminus in the ligand-independent activation domain. This extension renders PPAR-gamma2 more sensitive to insulin action. Since there is a Pro12Ala substitution in this domain, we tested whether it is related to type 2 diabetes or insulin resistance. Therefore, 131 type 2 diabetic patients and 312 normoglycemic control subjects were screened for the presence of the mutation and for major clinical and metabolic features. The frequency of the mutation did not differ significantly between diabetic patients and control subjects. BMI, insulin, and other metabolic and anthropometric variables were also not associated with the mutation. Although the study was carried out on a sufficiently large sample, the conclusions do not support a major role for the Pro12Ala substitution of the PPAR-gamma gene in the etiology of type 2 diabetes.
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Changes in tissue transglutaminase activity and expression during retinoic acid-induced growth arrest and apoptosis in primary cultures of human epithelial prostate cells. J Clin Endocrinol Metab 1999; 84:1463-9. [PMID: 10199796 DOI: 10.1210/jcem.84.4.5593] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We treated primary epithelial cells from human normal prostate (NEPC) and prostate cancer (CEPC) with all-trans-retinoic acid (RA) to study whether it regulates the activity of tissue transglutaminase (tTGase), an enzyme that accumulates in cells undergoing apoptosis. tTGase activity was assessed by [14C]spermidine incorporation; tTGase, P53, Bcl-2, and p21 protein levels were evaluated by Western blotting; and RA receptors (RAR alpha, -beta, and -gamma), tTGase, retinol-binding protein (RBP), and cellular RBP type I transcripts were determined by semiquantitative RT-PCR. After 72-96 h of 10(-6) mol/L RA treatment, cell growth inhibition and apoptosis were associated with increased tTGase activity in both NEPC and CEPC, and with increased tTGase protein and messenger ribonucleic acid levels only in NEPC. Moreover, RA down-regulated RAR alpha and -beta and increased RBP messenger ribonucleic acid levels in NEPC, whereas it increased RAR beta gene expression and decreased Bcl-2 protein levels in CEPC. Our results suggest that RA induces tTGase gene expression and enzyme activity in normal prostate cells, and that RA-regulated pathways are impaired in cancer cells. Moreover, down-regulation of Bcl-2 protein and up-regulation of RAR beta suggest that retinoid may act on the genetic defect responsible for prostate cancer progression.
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Abstract
In this study we investigated the activation of nuclear factor-kappaB in the carrageenin-induced rat pleurisy. We found that nuclear factor-kappaB DNA binding activity, measured in inflammatory cells which migrated into the pleural cavity, was detectable at 3 and 6 h, markedly increased at 24 h and decreased at 48 h after induction of the inflammation. The increase in nuclear factor-kappaB DNA binding activity paralleled both exudate formation and leukocyte infiltration. Treatment of animals with pyrrolidine dithiocarbamate, an inhibitor of nuclear factor-kappaB activation, inhibited the nuclear factor-kappaB DNA binding activity as well as exudate formation and leukocyte infiltration. These results indicate that nuclear factor-kappaB is activated in the carrageenin-induced pleurisy and suggest that its inhibition may represent a novel strategy for the modulation of inflammatory response.
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Mutations in the extracellular domain cause RET loss of function by a dominant negative mechanism. Mol Cell Biol 1998; 18:3321-9. [PMID: 9584172 PMCID: PMC108913 DOI: 10.1128/mcb.18.6.3321] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/1998] [Accepted: 03/19/1998] [Indexed: 02/07/2023] Open
Abstract
The RET proto-oncogene encodes a tyrosine kinase receptor expressed in neuroectoderm-derived cells. Mutations in specific regions of the gene are responsible for the tumor syndromes multiple endocrine neoplasia types 2A and 2B (MEN 2A and 2B), while mutations along the entire gene are involved in a developmental disorder of the gastrointestinal tract, Hirschsprung's disease (HSCR disease). Two mutants in the extracellular domain of RET, one associated with HSCR disease and one carrying a flag epitope, were analyzed to investigate the impact of the mutations on RET function. Both mutants were impeded in their maturation, resulting in the lack of the 170-kDa mature form and the accumulation of the 150-kDa immature form in the endoplasmic reticulum. Although not exposed on the cell surface, the 150-kDa species formed dimers and aggregates; this was more pronounced in a double mutant bearing a MEN 2A mutation. Tyrosine phosphorylation and the transactivation potential were drastically reduced in single and double mutants. Finally, in cotransfection experiments both mutants exerted a dominant negative effect over protoRET and RET2A through the formation of a heteromeric complex that prevents their maturation and function. These results suggest that HSCR mutations in the extracellular region cause RET loss of function through a dominant negative mechanism.
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A GTG to ATG novel point mutation at codon 804 in exon 14 of the RET proto-oncogene in two families affected by familial medullary thyroid carcinoma. Hum Mutat 1998; Suppl 1:S167-71. [PMID: 9452077 DOI: 10.1002/humu.1380110156] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Seventeen-year-long follow-up of a family affected by type 2A multiple endocrine neoplasia (MEN 2A). J Endocrinol Invest 1998; 21:87-92. [PMID: 9585381 DOI: 10.1007/bf03350320] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This paper reports the results of a 17-year-long follow-up covering 17 members of a family affected by multiple endocrine neoplasia (MEN) type 2A, first diagnosed in 1980. This family is enrolled in our screening program. The thyroid, parathyroid and adrenal glands of the family members were investigated using the most sophisticated and sensitive techniques which have become available during this period, and their DNA was genetically tested for detecting RET mutations. Thanks to the combination of these two approaches it was possible to confirm the diagnosis in the members concerned from the genetic point of view, and to achieve an early diagnosis in the young members of the last generation before the clinical onset of the disease. The detection of a RET mutation also prompted a prophylactic thyroidectomy in a four year-old boy, in a pre-tumoral stage of the disease. Lastly, evidence is provided that genetic analysis of the DNA of the chorionic villi can be carried out as a prenatal test during routine amniocentesis.
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Abstract
Medullary thyroid carcinomas (MTC) occur sporadically or as part of inherited multiple endocrine neoplasia (MEN) type 2 syndromes. To recognize misdiagnosed familial cases and to establish the frequency of somatic mutations, a series of 50 patients, clinically diagnosed with sporadic MTC, were analyzed for mutations in the RET proto-oncogene. The clinical management of the patient and of the family is different in the two cases. Germline mutations were detected in three independent cases, demonstrating that they were associated to familial MTC. The mutations affected exon 11 in two cases and exon 14 in one case. Somatic mutations were detected in eight patients (30%) and they were indicative of sporadic MTC. In seven cases the mutation affected codon 918 of exon 16 and in one case codon 634 in exon 11. No RET mutations were detected in the remaining patients. A different genetic and clinical management is proposed for individuals with a diagnosis of familial or sporadic MTC.
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A novel point mutation in the intracellular domain of the ret protooncogene in a family with medullary thyroid carcinoma. J Clin Endocrinol Metab 1997; 82:4176-8. [PMID: 9398735 DOI: 10.1210/jcem.82.12.4439] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Specific mutations in the ret protooncogene have been found associated with multiple endocrine neoplasia type 2A (MEN 2A) and type 2B (MEN 2B) and familial medullary thyroid carcinoma (FMTC). Mutations in one of five cysteine residues in the extracellular domain have been found in over 95% of families with MEN 2A and 88% of families with FMTC. In MEN 2B patients, a specific mutation at codon 918, substituting a threonine for a methionine, has been found in 95% of cases. In FMTC, in addition to the mutations of the extracellular cysteines, three intracellular base pair changes have been reported at codons 768 and 804. Here we describe a novel intracellular mutation in exon 15 of the ret gene that leads to the substitution of an alanine for a serine at codon 891 in a family with medullary thyroid carcinoma. This amino acid change may be important in determining substrate specificity or, alternatively, may play a role in ATP binding.
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Retinoic acid receptors alpha, beta and gamma, and cellular retinol binding protein-I expression in breast fibrocystic disease and cancer. Eur J Endocrinol 1997; 137:410-4. [PMID: 9368510 DOI: 10.1530/eje.0.1370410] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Retinoids seem to act as agents of chemoprevention and differentiation in breast diseases. Their action is mediated by nuclear receptors, retinoic acid receptors (RAR alpha, RAR beta, RAR gamma) and retinoid X receptors (RXR alpha, RXR beta, RXR gamma) and modulated by cellular retinol binding proteins (CRBP). There are few published data on CRBP expression. In this study, we evaluated the expression of RAR alpha, beta and gamma and CRBP type I (CRBP-I) gene expression in fibrocystic disease (FD) and in breast cancer (BC), studying 14 FD and 20 BC surgical samples by reverse transcription (RT)-PCR. We also evaluated mRNA concentrations in cancer samples by a semiquantitative PCR method, co-amplifying RAR alpha, RAR beta and CRBP-I genes with an unrelated gene, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), as internal control. All benign and malignant breat tissues expressed RAR alpha, beta and gamma, and CRBP-I mRNAs. A greater concentration of RAR beta mRNA was detected in cancer tissues with lower oestrogen and progesterone receptor concentrations, whereas RAR alpha was detected in variable concentrations that were not related to those of steroid receptors. The CRBP-I concentration was similar in all samples studied. We demonstrated that all three RARs and CRBP-I transcripts are expressed in FD, and that RAR beta, RAR gamma and CRBP-I mRNAs also are present in BC tissues. This indicates that both malignant and benign breast tissues may be target for retinoids, justifying the use of natural and synthetic vitamin A derivatives in the chemoprevention of breast disease.
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Abstract
Adipose tissue is an important storage depot for retinol, but there are no data regarding retinol mobilization from adipose stores. To address this, dibutyryl cAMP was provided to murine BFC-1beta adipocytes and its effects on retinol efflux assessed. High performance liquid chromatography analysis of retinol and retinyl esters in adipocytes and media indicated that cAMP stimulated, in a time- and dose-dependent manner, retinol accumulation in the culture media and decreased cellular retinyl ester concentrations. Study of adipocyte retinol-binding protein synthesis and secretion indicated that cAMP-stimulated retinol efflux into the media did not result from increased retinol-retinol-binding protein secretion but was dependent on the presence of fetal bovine serum in the culture media. Since our data suggested that retinyl esters can be hydrolyzed by a cAMP-dependent enzyme like hormone-sensitive lipase (HSL), in separate studies, we purified a HSL-containing fraction from BFC-1beta adipocytes and demonstrated that it catalyzed retinyl palmitate hydrolysis. Homogenates of Chinese hamster ovary cells overexpressing HSL catalyzed retinyl palmitate hydrolysis in a time-, protein-, and substrate-dependent manner, with an apparent Km for retinyl palmitate of 161 microM, whereas homogenates from control Chinese hamster ovary cells did not.
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Identification of a novel retinoic acid response element in the promoter region of the retinol-binding protein gene. J Biol Chem 1996; 271:25524-32. [PMID: 8810324 DOI: 10.1074/jbc.271.41.25524] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We have previously demonstrated that the retinol-binding protein (RBP) gene is induced by retinoids in hepatoma cells. In this report, we define in greater detail the region that mediates the retinoic acid response of the gene. It consists of two degenerate retinoic acid response elements, separated by 30 nucleotides that encompass a GC-rich Sp1 consensus-like sequence. We demonstrate that the entire region, as well as each element taken singly, can bind the retinoic acid receptors as homo- and heterodimers with low affinity. However, only the entire region is able to confer retinoic acid inducibility to a heterologous promoter. We also show that the correct phasing of the DNA segment is necessary to achieve full responsiveness. Site-directed mutants in each element retained partial induction after transfection, while the double mutant was no longer responsive, suggesting that the two elements act synergistically. Mutational analysis of the Sp1 binding site and cotransfection experiments revealed that Sp1 or a related protein plays an important role in the transcription of the gene. Thus, the retinoic acid induction of the RBP gene is mediated by a novel and complex responsive unit formed by two distinct elements located in a specific sequence context and the interplay of the retinoid receptors with Sp1 is required for induction.
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Molecular heterogeneity of RET loss of function in Hirschsprung's disease. EMBO J 1996; 15:2717-25. [PMID: 8654369 PMCID: PMC450207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The RET proto-oncogene encodes a receptor with tyrosine kinase activity (RET) that is involved in several neoplastic and non-neoplastic diseases. Oncogenic activation of RET, achieved by different mechanisms, is detected in a sizeable fraction of human thyroid tumors, as well as in multiple endocrine neoplasia types 2A and 2B (MEN2A and MEN2B) and familial medullary thyroid carcinoma tumoral syndromes. Germline mutations of RET have also been associated with a non-neoplastic disease, the congenital colonic aganglionosis, i.e. Hirschsprung's disease (HSCR). To analyse the impact of HSCR mutations on RET function, we have introduced into wild-type RET and activated RET(MEN2A) and RET(MEN2B) alleles three missense mutations associated with HSCR. Here we show that the three mutations caused a loss of function of RET when assayed in two model cell systems, NIH 3T3 and PC12 cells. The effect of different HSCR mutations was due to different molecular mechanisms. The HSCR972 (Arg972-->Gly) mutation, mapping in the intracytoplasmic region of RET, impaired its tyrosine kinase activity, while two extracellular mutations, HSCR32 (Ser32-->Leu) and HSCR393 (Phe393-->Leu), inhibited the biological activity of RET by impairing the correct maturation of the RET protein and its transport to the cell surface.
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37
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A primary, lateral-cervical medullary thyroid carcinoma: a case report. J Clin Endocrinol Metab 1996; 81:1784-6. [PMID: 8626835 DOI: 10.1210/jcem.81.5.8626835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Medullary thyroid carcinoma (MTC) arises from the parafollicular cells of the thyroid and occurs in a sporadic or in an inherited form. We present a case of an aberrant MTC in a patient with a functioning thyroid gland. At surgical dissection, the thyroid was present in its anatomical site with a nodule in the upper one third of the right lobe. A mass was also found in a lateral-cervical position distinct from the thyroid gland. Histological examination showed the mass to be the primary MTC, whereas the thyroid nodule was a follicular adenoma. Analysis of DNA extracted from the MTC, from the adenoma, and from peripheral blood revealed a mutation within exon 16 of the RET proto-oncogene only in the DNA from the tumor. The reported case represents a sporadic MTC in an aberrant localization, probably originating from a developmental abnormality of the primordial C cells. This event might have occurred during the migration and/or differentiation of the C cells and might be related to, or caused by, the mutated RET proto-oncogene.
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A mutation in the RET proto-oncogene in Hirschsprung's disease affects the tyrosine kinase activity associated with multiple endocrine neoplasia type 2A and 2B. Biochem J 1996; 314 ( Pt 2):397-400. [PMID: 8670046 PMCID: PMC1217061 DOI: 10.1042/bj3140397] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We demonstrate that a Hirschsprung (HSCR) mutation in the tyrosine kinase domain of the RET proto-oncogene abolishes in cis the tyrosine-phosphorylation associated with the activating mutation in multiple endocrine neoplasia type 2A (MEN2A) in transiently transfected Cos cells. Yet the double mutant RET2AHS retains the ability to form stable dimers, thus dissociating the dimerization from the phosphorylation potential. Co-transfection experiments with single and double mutants carrying plasmids RET2A and RET2AHS in different ratios drastically reduced the phosphorylation levels of the RET2A protein, suggesting a dominant-negative effect of the HSCR mutation. Also, the phosphorylation associated with the multiple endocrine neoplasia type 2B (MEN2B) allele was affected in experiments with single and double mutants carrying plasmids co-transfected under the same conditions. Finally, analysis of the enzymic activity of MEN2A and MEN2B tumours confirmed the relative levels of tyrosine phosphorylation observed in Cos cells, indicating that this condition, in vivo, may account for the RET transforming potential.
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Point mutation of the RET proto-oncogene in the TT human medullary thyroid carcinoma cell line. Biochem Biophys Res Commun 1995; 207:1022-8. [PMID: 7864888 DOI: 10.1006/bbrc.1995.1287] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The RET proto-oncogene encodes a tyrosine-kinase receptor specifically expressed in tissues of neuroectodermal origin. Recently specific point mutations of RET have been demonstrated to be responsible for the Multiple Endocrine Neoplasia type 2A and 2B and Familial Medullary Thyroid Carcinoma syndromes, characterized by the occurrence of medullary thyroid carcinomas. Here we report that a human medullary thyroid carcinoma cell line, the TT cell line, harbours a MEN2A-type mutation, specifically a cysteine to triptophan substitution at the level of the RET codon 634. This mutation is heterozygous and both normal and mutated alleles are expressed. We suggest that the TT cell line could be a useful cell system to investigate the role played by the RET oncogene in the transformation and differentiation of human thyroid C-cells.
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Parental imprinting of rat insulin-like growth factor II gene promoters is coordinately regulated. J Biol Chem 1994; 269:23970-5. [PMID: 7929045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The insulin-like growth factor II (IGF-II) gene is parentally imprinted in the mouse and human species. By following the inheritance of natural polymorphisms of IGF-II mRNA, we demonstrated that the tissue-specific parental imprinting of the IGF-II gene is conserved in the rat. The expression of the paternal IGF-II allele exceeded by more than 3 orders of magnitude that of the maternal allele in livers of 3-day-old Wistar x Fisher interstrain rat crosses. In contrast, the two alleles were both expressed in the rat central nervous system, which is also the only district of the organism where this gene is active in adult rodents. We also analyzed the allelic usage of the three IGF-II promoters, which generate alternatively spliced transcripts, and showed that parental imprinting of all transcription starts sites is coordinately regulated since P1, P2, and P3 are all repressed on the maternal allele in neonatal rat liver, and all of them are activated on both alleles in the choroid plexus of the central nervous system. RNase protection assays demonstrated that the activity ratio of the three IGF-II promoters can be different in tissues that show the same imprinting mode.
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Retinoids regulate expression of the retinol-binding protein gene in hepatoma cells in culture. J Cell Physiol 1994; 160:596-602. [PMID: 8077297 DOI: 10.1002/jcp.1041600323] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The expression of the gene coding for retinol-binding protein has been studied in a system of cultured human hepatoma cells exposed to retinoids. We report that the gene is positively modulated by retinol and retinoic acid in a time- and dose-dependent fashion. The stimulation at the mRNA level is paralleled by an increase of the corresponding protein that is secreted in the presence of the physiological ligand. An RBP-CAT chimeric gene, introduced by transfection, is also responsive to the treatment, showing the gene dose-dependency as the endogenous gene. These results demonstrate that retinoids up-regulate the RBP gene and that the control takes place at transcriptional level.
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Abstract
The occurrence of mutations in the RET protooncogene has been investigated in 12 multiple endocrine neoplasia type 2A families and 18 cases of sporadic thyroid medullary carcinomas and pheochromocytomas. Ten of 12 families showed single base substitutions in the RET protooncogene exons 10 and 11, coding for the extracellular domain of the protein. Tumor tissues from 2 multiple endocrine neoplasia type 2A patients were analyzed at the DNA and ribonucleic acid levels and revealed the same heterozygous mutations found in the peripheral blood lymphocytes. This demonstrates that both the normal and mutant alleles are expressed. No mutations in these exons were detected in the 18 cases of sporadic tumors investigated. These data provided further evidence that the mutated RET protooncogene acts in a dominant fashion and is responsible for the pathogenesis of this syndrome.
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Activation of the galectin-1 (L-14-I) gene from nonexpressing differentiated cells by fusion with undifferentiated and tumorigenic cells. CELL GROWTH & DIFFERENTIATION : THE MOLECULAR BIOLOGY JOURNAL OF THE AMERICAN ASSOCIATION FOR CANCER RESEARCH 1994; 5:769-775. [PMID: 7524630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Expression of the galectin-1 (L-14-I) gene, elevated in most differentiated and transformed cell lines, has been studied in cell hybrid systems. Fusion of L-14-I nonproducing rat liver differentiated FAO cells with dedifferentiated rat liver BRL3A cells leads to extinction of liver-specific gene expression while L-14-I mRNA levels remain high. Interspecific hybrids produced by fusion of tumorigenic human osteosarcoma 143TK- with FAO cells show loss of both differentiated functions and tumorigenic phenotype and activation of the FAO L-14-I alleles. Increased expression of rat L-14-I alleles was also observed in human osteosarcoma x rat thyroid cells transient heterokaryons. The data presented here show that expression of the L-14-I gene is subject to dominant positive control and that it correlates with loss of differentiation-specific functions, but it is independent from tumorigenicity. L-14-I activation in FAO cells is achieved by treatment with 5-azacytidine. This result suggests that DNA demethylation is responsible or a prerequisite for L-14-I activation in hybrids.
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Cellular retinoic-acid-binding-protein and retinol-binding-protein mRNA expression in the cells of the rat seminiferous tubules and their regulation by retinoids. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 211:835-42. [PMID: 8382159 DOI: 10.1111/j.1432-1033.1993.tb17616.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The levels of the mRNA corresponding to the intracellular binding proteins for retinoic acid and retinol (CRABP1 and CRBP1, respectively) were studied in primary cultures of somatic and germ cells of the rat seminiferous tubules. We show that the CRABP1 mRNA is expressed in Sertoli and germ cells and a single molecular species of mRNA is detected. CRBP1 mRNA is detected in Sertoli and peritubular cells. The regulation of the expression of both genes by retinoids was studied in Sertoli cells. CRABP1 mRNA levels are not affected by either retinoic acid or retinol, whereas both compounds positively regulate CRBP1 mRNA synthesis in a dose-dependent manner. A fivefold increase in CRBP1 mRNA levels was observed 32-48 h after addition of either agent. These results demonstrate that in Sertoli cells the expression of CRABP1 is not affected by retinoids, similar to the situation observed in vivo and in other in-vitro cultures. CRBP1-gene expression is, instead, induced and the variations in CRBP1-mRNA levels may regulate the intracellular concentrations of retinoids, as a response to changes in the vitamin-A nutritional status.
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Extinction of insulin-like growth factor II gene expression in intratypic hybrids of rat liver cells. Mol Endocrinol 1993; 7:131-41. [PMID: 8446103 DOI: 10.1210/mend.7.1.8446103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The expression of the developmentally regulated insulin-like growth factor II (IGF-II) gene has been studied in somatic cell hybrids derived from rat liver cells. BRL3A cells, dedifferentiated variants of rat hepatocytes, producing high levels of IGF-II, were fused to BRL30E or FAO cells of the same embryonic lineage but not expressing detectable levels of IGF-II mRNA. We report here that the IGF-II gene is subject to extinction, since its specific RNA levels are decreased both in heterokaryons and stable cell hybrids. Transcriptional analysis in isolated nuclei from parental and hybrid cells showed that the IGF-II gene is transcribed at a similar rate in all cell types. Likewise, the stability of IGF-II cytoplasmic mRNA was equivalent in the high-expressing parental cells and in the hybrids. In contrast, the distribution of IGF-II mRNA between the nuclear and the cytoplasmic compartments differed markedly in parental and hybrid cell lines. The data presented show that the expression of the IGF-II gene is subject to a dominant negative control and suggest that the phenomenon involves mechanisms that operate at the posttranscriptional level.
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Regulation of insulin-like-growth-factor-II gene expression in rat liver cells. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 209:445-52. [PMID: 1396718 DOI: 10.1111/j.1432-1033.1992.tb17308.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The rat insulin-like-growth-factor-(IGF)-II gene is expressed at high levels during embryonic and fetal life and at low levels in adult animals. To study the regulation of IGF-II gene expression, we analyzed the synthesis and localization of the IGF-II transcripts in cultured rat liver cells either expressing (BRL3A cells) or not expressing (BRL30E and FAO cells) the IGF-II mRNA. The IGF-II gene is transcribed at a similar rate in expressing and non-expressing cells, whereas its nuclear and cytoplasmic RNA levels are diversely distributed in the cells. IGF-II RNA is more abundant in the cytoplasmic than in the nuclear RNA fraction of BRL3A cells and is present in the nucleus but not in the cytoplasm of the FAO cells. However, both precursor and mature IGF-II nuclear RNA levels are reduced in FAO cells. Our data indicate that the IGF-II gene expression is regulated by mechanisms affecting the subcellular distribution and the abundance of the transcripts.
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Vitamin A intake and in vivo expression of the genes involved in retinol transport. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 196:211-7. [PMID: 2001700 DOI: 10.1111/j.1432-1033.1991.tb15806.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Two different metabolic alterations in vitamin A status are known to cause changes in the amount of circulating retinol-binding protein (RBP) and cellular retinol-binding protein (CRBP) in experimental animals; namely vitamin A deficiency, characterized by depleted retinol-liver stores and hypervitaminosis A, characterized by hepatic accumulation of retinyl esters. We have induced vitamin A deficiency and hypervitaminosis A in two groups of rats with the aim of determining whether the expression of the genes coding for these two proteins might be directly regulated by retinol. Using human RBP and CRBP cDNAs as probes, we measured the rate of transcription of the two genes in liver nuclei from control and treated rats by run-on transcription assays, and the steady-state level of the mRNAs by Northern blot analysis of total liver RNA. The distribution profile of RBP and CRBP mRNAs on fractionated liver polysomes was also examined. We have found a threefold decrease in the hepatic level of CRBP mRNA in vitamin-A-deficient animals, while the RBP mRNA is not affected by this nutritional deprivation. The decreases does not correspond to a lower transcription rate of the gene and therefore it is likely to result from lower stability of the CRBP mRNA. In hypervitaminosis A, we do not observe any differences in both the steady-state level of the mRNAs and in the rate of transcription of the two genes. The results are discussed in terms of retinol-dependent stabilization of the mRNA coding for CRBP.
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Extinction of human insulin-like growth factor II expression in somatic cell hybrids. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1991; 293:77-83. [PMID: 1767743 DOI: 10.1007/978-1-4684-5949-4_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Extinction of retinol-binding protein gene expression in somatic cell-hybrids: identification of the target sequences. Nucleic Acids Res 1990; 18:7235-42. [PMID: 2259620 PMCID: PMC332858 DOI: 10.1093/nar/18.24.7235] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Retinol-Binding Protein (RBP) is expressed primarily in the liver. The regulatory elements involved in its tissue-specific expression have been identified and mapped to the 5' flanking region of the RBP gene. In this paper heterokaryons and somatic cell-hybrids have been produced and analysed in order to demonstrate that the RBP gene is subject to extinction and to identify the target sequences of this phenomenon. We show here that the gene is extinguished in fusions of hepatoma with a variety of cells of different species and embryonic lineages. The repression is not due to loss of the gene and occurs also when chromosome 10, where the gene is located, is inherited from the expressing parental cell-type. Hybrid clones were transfected with constructs carrying DNA segments of different lengths from the 5' flanking region of the RBP gene fused to a reporter gene. We demonstrate that extinction takes place also on an exogenous RBP-CAT gene, mimicking the phenomenon observed with the endogenous gene in its chromosomal location. Moreover, we identify and map the target sequences of the putative extinguishing function. Our data thus show that extinction of RBP is mediated through the DNA segment that is involved in its tissue-specific expression.
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