The Somatostatin Analogue Octreotide Inhibits Growth of Small Intestine Neuroendocrine Tumour Cells

Octreotide is a widely used synthetic somatostatin analogue that significantly improves the management of neuroendocrine tumours (NETs). Octreotide acts through somatostatin receptors (SSTRs). However, the molecular mechanisms leading to successful disease control or symptom management, especially when SSTRs levels are low, are largely unknown. We provide novel insights into how octreotide controls NET cells. CNDT2.5 cells were treated from 1 day up to 16 months with octreotide and then were profiled using Affymetrix microarray analysis. Quantitative real-time PCR and western blot analyses were used to validate microarray profiling in silico data. WST-1 cell proliferation assay was applied to evaluate cell growth of CNDT2.5 cells in the presence or absence of 1 mM octreotide at different time points. Moreover, laser capture microdissected tumour cells and paraffin embedded tissue slides from SI-NETs at different stages of disease were used to identify transcriptional and translational expression. Microarrays analyses did not reveal relevant changes in SSTR expression levels. Unexpectedly, six novel genes were found to be upregulated by octreotide: annexin A1 (ANXA1), rho GTPase-activating protein 18 (ARHGAP18), epithelial membrane protein 1 (EMP1), growth/differentiation factor 15 (GDF15), TGF-beta type II receptor (TGFBR2) and tumour necrosis factor (ligand) superfamily member 15 (TNFSF15). Furthermore, these novel genes were expressed in tumour tissues at transcript and protein levels. We suggest that octreotide may use a potential novel framework to exert its beneficial effect as a drug and to convey its action on neuroendocrine cells. Thus, six novel genes may regulate cell growth and differentiation in normal and tumour neuroendocrine cells and have a role in a novel octreotide mechanism system

Évaluer l’endurance des muscles extenseurs cervicaux chez les cervicalgiques chroniques : quels critères cliniques discriminants ?

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Paraneoplastic Antigen Ma2 Autoantibodies as Specific Blood Biomarkers for Detection of Early Recurrence of Small Intestine Neuroendocrine Tumors

Small intestine neuroendocrine tumors (SI-NETs) belong to a rare group of cancers. Most patients have developed metastatic disease at the time of diagnosis, for which there is currently no cure. The delay in diagnosis is a major issue in the clinical management of the patients and new markers are urgently needed. We have previously identified paraneoplastic antigen Ma2 (PNMA2) as a novel SI-NET tissue biomarker. Therefore, we evaluated whether Ma2 autoantibodies detection in the blood stream is useful for the clinical diagnosis and recurrence of SI-NETs

Transcription factor regulation can be accurately predicted from the presence of target gene signatures in microarray gene expression data

Deciphering transcription factor networks from microarray data remains difficult. This study presents a simple method to infer the regulation of transcription factors from microarray data based on well-characterized target genes. We generated a catalog containing transcription factors associated with 2720 target genes and 6401 experimentally validated regulations. When it was available, a distinction between transcriptional activation and inhibition was included for each regulation. Next, we built a tool (www.tfacts.org) that compares submitted gene lists with target genes in the catalog to detect regulated transcription factors. TFactS was validated with published lists of regulated genes in various models and compared to tools based on in silico promoter analysis. We next analyzed the NCI60 cancer microarray data set and showed the regulation of SOX10, MITF and JUN in melanomas. We then performed microarray experiments comparing gene expression response of human fibroblasts stimulated by different growth factors. TFactS predicted the specific activation of Signal transducer and activator of transcription factors by PDGF-BB, which was confirmed experimentally. Our results show that the expression levels of transcription factor target genes constitute a robust signature for transcription factor regulation, and can be efficiently used for microarray data mining

Hepatocyte MyD88 affects bile acids, gut microbiota and metabolome contributing to regulate glucose and lipid metabolism

OBJECTIVE: To examine the role of hepatocyte myeloid differentiation primary-response gene 88 (MyD88) on glucose and lipid metabolism. DESIGN: To study the impact of the innate immune system at the level of the hepatocyte and metabolism, we generated mice harbouring hepatocyte-specific deletion of MyD88. We investigated the impact of the deletion on metabolism by feeding mice with a normal control diet or a high-fat diet for 8 weeks. We evaluated body weight, fat mass gain (using time-domain nuclear magnetic resonance), glucose metabolism and energy homeostasis (using metabolic chambers). We performed microarrays and quantitative PCRs in the liver. In addition, we investigated the gut microbiota composition, bile acid profile and both liver and plasma metabolome. We analysed the expression pattern of genes in the liver of obese humans developing non-alcoholic steatohepatitis (NASH). RESULTS: Hepatocyte-specific deletion of MyD88 predisposes to glucose intolerance, inflammation and hepatic insulin resistance independently of body weight and adiposity. These phenotypic differences were partially attributed to differences in gene expression, transcriptional factor activity (ie, peroxisome proliferator activator receptor-α, farnesoid X receptor (FXR), liver X receptors and STAT3) and bile acid profiles involved in glucose, lipid metabolism and inflammation. In addition to these alterations, the genetic deletion of MyD88 in hepatocytes changes the gut microbiota composition and their metabolomes, resembling those observed during diet-induced obesity. Finally, obese humans with NASH displayed a decreased expression of different cytochromes P450 involved in bioactive lipid synthesis. CONCLUSIONS: Our study identifies a new link between innate immunity and hepatic synthesis of bile acids and bioactive lipids. This dialogue appears to be involved in the susceptibility to alterations associated with obesity such as type 2 diabetes and NASH, both in mice and humans

Environmental hypoxia favors myoblast differentiation and fast phenotype but blunts activation of protein synthesis after resistance exercise in human skeletal muscle

We hypothesized that a single session of resistance exercise performed in moderate hypoxic (FiO2: 14%) environmental conditions would potentiate the anabolic response during the recovery period spent in normoxia. Twenty subjects performed a 1-leg knee extension session in normoxic or hypoxic conditions. Muscle biopsies were taken 15 min and 4 h after exercise in the vastus lateralis of the exercised and the nonexercised legs. Blood and saliva samples were taken at regular intervals before, during, and after the exercise session. The muscle fractional-protein synthetic rate was determined by deuterium incorporation into proteins, and the protein-degradation rate was determined by methylhistidine release from skeletalmuscle.Wefoundthat:1)hypoxiablunted the activation of protein synthesis after resistance exercise; 2) hypoxia down-regulated the transcriptional program of autophagy; 3) hypoxia regulated the expression of genes involved in glucose metabolism at rest and the genes involved in myoblast differentiation and fusion and in muscle contraction machinery after exercise; and 4) the hypoxia-inducible factor-1alpha pathway was not activated at the time points studied. Contrary to our hypothesis, environmental hypoxia did not potentiate the short-term anabolic response after resistance exercise, but it initiated transcriptional regulations that could potentially translate into satellite cell incorporation and higher force production in the long term

miR-15a-5p and miR-21-5p contribute to chemoresistance in cytogenetically normal acute myeloid leukaemia by targeting PDCD4, ARL2 and BTG2

Cytarabine and daunorubicin are old drugs commonly used in the treatment of acute myeloid leukaemia (AML). Refractory or relapsed disease because of chemotherapy resistance is a major issue. microRNAs (miRNAs) were incriminated in resistance. This study aimed to identify miRNAs involved in chemoresistance in AML patients and to define their target genes. We focused on cytogenetically normal AML patients with wild-type NPM1 without FLT3-ITD as the treatment of this subset of patients with intermediate-risk cytogenetics is not well established. We analysed baseline AML samples by small RNA sequencing and compared the profile of chemoresistant to chemosensitive AML patients. Among the miRNAs significantly overexpressed in chemoresistant patients, we revealed miR-15a-5p and miR-21-5p as miRNAs with a major role in chemoresistance in AML. We showed that miR-15a-5p and miR-21-5p overexpression decreased apoptosis induced by cytarabine and/or daunorubicin. PDCD4, ARL2 and BTG2 genes were found to be targeted by miR-15a-5p, as well as PDCD4 and BTG2 by miR-21-5p. Inhibition experiments of the three target genes reproduced the functional effect of both miRNAs on chemosensitivity. Our study demonstrates that miR-15a-5p and miR-21-5p are overexpressed in a subgroup of chemoresistant AML patients. Both miRNAs induce chemoresistance by targeting three pro-apoptotic genes PDCD4, ARL2 and BTG2

Signal transduction by the interleukin-9 receptor

Interleukin-9 (IL-9) is a pleiotropic TH2 cytokine involved in anti-parasite immunity, asthma and lymphoma development. It regulates survival, growth, and differentiation of target cells, such as lymphocytes and mast cells. The present work aimed at identifying intracellular signals triggered by the binding of IL-9 to its membrane receptor. This receptor is a complex composed of two proteins: the IL-9 receptor itself (IL-9R), and the γc chain. Both proteins are associated with a tyrosine kinase of the JAK family, JAK1 and JAK3, respectively. These enzymes, which are activated in the presence of IL-9, are most likely responsible for the phosphorylation a single IL-9R tyrosine that we identified by mutagenesis. Our data suggest that this phosphoryled amino-acid is recognized by three transcription factors of the STAT family; i.e. STAT1, STAT3 and STAT5. Based on the literature, receptor-associated STATs are activated by JAK kinases, dissociate from the receptor, dimerize and migrate to the nucleus, where they regulate gene transcription. We showed that most genes regulated but IL-9 are controlled by this pathways. It is the case if Lys-6A/E, a gene involved in lymphocyte activation. Some of these genes are regulated by a specific STAT factor, whereas others are equally induced via STAT1, STAT3 or STAT5. These observations provide an explanation for differences in gene regulation by IL-2, IL-3, IL-6, IL-9 and interferon γ in our system. Our results also indicated that STAT transcription factors play a key role in IL-9-medaited cell proliferation and inhibition of apoptosis induced by glucocorticoids. It is likely that these effects of IL0 are also mediated by regulation of genes, the nature of which is still unknown, however. Implication of STATs in cell survival and proliferation prompted us to investigate their activation in tumorigenic clones derived from IL-9 dependent cell lines. In two murine models established in our laboratory, we observed that constitutive STAT activation was associated with tumorgenesis. These models should help us to identify STAT-regulated genes involved in proliferation. Taken together, our results point to a role for STAT factors in lymphocytic oncogenesis. Future studies will have to determine whether STATs are useful target in lymphoma and leukemia therapyL’interleukine-9 (IL-9) est une cytokine impliquée dans les réponses immunitaires de type TH2, responsables des réactions contre les parasites et de certaines formes d’asthme. IL-9 pourrait également favoriser le développement de lymphomes et leucémies. Elle régule la survie, la multiplication et la différenciation de nombreuses cellules, notamment des mastocytes et des lymphocytes. Notre but était d’identifier les signaux intracellulaires activés par la fixation de l’IL-9 sur son récepteur. Celui-ci est formé de deux protéines transmembranaires : le récepteur de l’IL-9 proprement dit (IL-9R), et γc, qui est également associée aux récepteurs des interleukines 2, 4, 7 et 15. Chacune de ces deux xhaïnes est liée à une tyrosine kinase de la famille des JAK : JAK1 et JAK3, respectivement. Nous avons pu montrer que ces enzymes sont activées en présence d’IL-9, et phosphorylent une seule tyrosine d’IL-9R, identifiée par mutagène. Après phosphorylation, cet acide aminé est reconnu par des facteurs de transcriptions de la famille STAT : STAT1, STAT3 et STAT5. Ces protéines sont probablement activées directement par JAK1 ou JAK3, ce qui permet leur dimérisation et leur migration vers le noyau de la cellule, où elles régulent la transcription de certains gènes, en se fixant sur leur partie promotrice. Nous avons démontré que cette voie de transduction du signal joue un rôle majeur dans le contrôle de l’expression des gènes par l’IL-9. Certains de ces gènes comme ly-6A/E, sont régulés plus spécifiquement par certains facteurs STAT activés par l’IL-9, alors que d’autres, comme pim1, sont induits indifféremment via STAT1, STAT3 ouSTAT5. Ces observations permettent d’expliquer les différences entre les effets de l’IL-2, l’IL-3, l’IL-6, l’IL-9 et l’interféron-γ dans notre système, en fonction du type de STATS qu’ils activent. Nos résultats indiquent que les protéines STAT sont également les médiateurs des activités de l’IL-9 sur les lymphomes et les lignées lymphoïdes : la stimulation de la croissance cellulaire et l’inhibition de l’apoptose induite par les glucocorticoïdes. Ces effets dépendent probablement aussi de l’activation de gènes, dont la nature reste à déterminer. Ces observations nous ont poussés à étudier le rôle des STAT dans l’oncogène des lymphocytes. Dans deux modèles murins établis dans notre laboratoire, nous avons observé que l’activation constitutive de STAT5 était corrélée avec la transformation de cellules en clones tumoraux. Des recherches ultérieures devront déterminer si les STAT sont des cibles thérapeutiques de choix pour le traitement de certains types de lymphomes et leucémiesThèse de doctorat en sciences pharmaceutiques (médecine expérimentale) -- UCL, 199