Diabetic cardiomyopathy: effects of fenofibrate and metformin in an experimental model – the Zucker diabetic rat

<p>Abstract</p> <p>Background</p> <p>Diabetic cardiomyopathy (DCM) contributes to cardiac failure in diabetic patients. It is characterized by excessive lipids accumulation, with increased triacylglycerol (TAG) stores, and fibrosis in left ventricle (LV). The mechanisms responsible are incompletely known and no specific treatment is presently defined. We evaluated the possible usefulness of two molecules promoting lipid oxidation, fenofibrate and metformin, in an experimental model of DCM, the Zucker diabetic rat (ZDF).</p> <p>Methods</p> <p>ZDF and controls (C) rats were studied at 7, 14 and 21 weeks. After an initial study at 7 weeks, ZDF rats received no treatment, metformin or fenofibrate until final studies (at 14 or 21 weeks). C rats received no treatment. Each study comprised measurements of metabolic parameters (plasma glucose, TAG, insulin levels) and sampling of heart for histology and measurements of TAG content and relevant mRNA concentration.</p> <p>Results</p> <p>ZDF rats were insulin-resistant at 7 weeks, type 2 diabetic at 14 weeks and diabetic with insulin deficiency at 21 weeks. Their plasma TAG levels were increased. ZDF rats had at 7 weeks an increased LV TAG content with some fibrosis. LV TAG content increased in untreated ZDF rats at 14 and 21 weeks and was always higher than in C. Fibrosis increased also moderately in untreated ZDF rats. Metformin and fenofibrate decreased plasma TAG concentrations. LV TAG content was decreased by metformin (14 and 21 weeks) and by fenofibrate (14 weeks). Fibrosis was reduced by fenofibrate only and was increased by metformin. Among the mRNA measured, fenofibrate increased Acyl-CoA Oxidase mRNA level, metformin decreased Acyl-CoA Synthase and increased AdipoR1 and pro-inflammatory mRNA levels.</p> <p>Conclusion</p> <p>Fenofibrate had favourable actions on DCM. Metformin had beneficial effect on TAG content but not on fibrosis. PPARα agonists could be useful for the prevention and treatment of DCM.</p

HTLV-1 propels thymic human T cell development in “human immune system” Rag2-/- gamma c-/- Mice

Alteration of early haematopoietic development is thought to be responsible for the onset of immature leukemias and lymphomas. We have previously demonstrated that TaxHTLV-1 interferes with ß- selection, an important checkpoint of early thymopoiesis, indicating that human T-cell leukemia virus type 1 (HTLV-1) infection has the potential to perturb thymic human αβ T-cell development. To verify that inference and to clarify the impact of HTLV-1 infection on human T-cell development, we investigated the in vivo effects of HTLV-1 infection in a “Human Immune System” (HIS) Rag2-/-γc-/- mouse model. These mice were infected with HTLV-1, at a time when the three main subpopulations of human thymocytes have been detected. In all but two inoculated mice, the HTLV-1 provirus was found integrated in thymocytes; the proviral load increased with the length of the infection period. In the HTLV-1-infected mice we observed alterations in human T-cell development, the extent of which correlated with the proviral load. Thus, in the thymus of HTLV-1-infected HIS Rag2-/-γc-/- mice, mature single-positive (SP) CD4+ and CD8+ cells were most numerous, at the expense of immature and double-positive (DP) thymocytes. These SP cells also accumulated in the spleen. Human lymphocytes from thymus and spleen were activated, as shown by the expression of CD25: this activation was correlated with the presence of tax mRNA and with increased expression of NF-kB dependent genes such as bfl-1, an anti-apoptotic gene, in thymocytes. Finally, hepato-splenomegaly, lymphadenopathy and lymphoma/thymoma, in which Tax was detected, were observed in HTLV-1-infected mice, several months after HTLV-1 infection. These results demonstrate the potential of the HIS Rag2-/-γc-/- animal model to elucidate the initial steps of the leukemogenic process induced by HTLV-1

Inhibition of DNA methylation promotes breast tumor sensitivity to netrin-1 interference

In a number of human cancers, NTN1 upregulation inhibits apoptosis induced by its so-called dependence receptors DCC and UNC5H, thus promoting tumor progression. In other cancers however, the selective inhibition of this dependence receptor death pathway relies on the silencing of pro-apoptotic effector proteins. We show here that a substantial fraction of human breast tumors exhibits simultaneous DNA methylation-dependent loss of expression of NTN1 and of DAPK1, a serine threonine kinase known to transduce the netrin-1 dependence receptor pro-apoptotic pathway. The inhibition of DNA methylation by drugs such as decitabine restores the expression of both NTN1 and DAPK1 in netrin-1-low cancer cells. Furthermore, a combination of decitabine with NTN1 silencing strategies or with an anti-netrin-1 neutralizing antibody potentiates tumor cell death and efficiently blocks tumor growth in different animal models. Thus, combining DNA methylation inhibitors with netrin-1 neutralizing agents may be a valuable strategy for combating cancer

HTLV-1 propels thymic human T cell development in “human immune system” Rag2-/- IL-2R γc-/- Mice

Alteration of early haematopoietic development is thought to be responsible for the onset of immature leukemias and lymphomas. We have previously demonstrated that TaxHTLV-1 interferes with ß-selection, an important checkpoint of early thymopoiesis, indicating that human T-cell leukemia virus type 1 (HTLV-1) infection has the potential to perturb thymic human αβ T-cell development. To verify that inference and to clarify the impact of HTLV-1 infection on human T-cell development, we investigated the in vivo effects of HTLV-1 infection in a “Human Immune System” (HIS) Rag2-/-γc-/- mouse model. These mice were infected with HTLV-1, at a time when the three main subpopulations of human thymocytes have been detected. In all but two inoculated mice, the HTLV-1 provirus was found integrated in thymocytes; the proviral load increased with the length of the infection period. In the HTLV-1-infected mice we observed alterations in human T-cell development, the extent of which correlated with the proviral load. Thus, in the thymus of HTLV-1-infected HIS Rag2-/-γc-/- mice, mature single-positive (SP) CD4+ and CD8+ cells were most numerous, at the expense of immature and double-positive (DP) thymocytes. These SP cells also accumulated in the spleen. Human lymphocytes from thymus and spleen were activated, as shown by the expression of CD25: this activation was correlated with the presence of tax mRNA and with increased expression of NF-kB dependent genes such as bfl-1, an anti-apoptotic gene, in thymocytes. Finally, hepato-splenomegaly, lymphadenopathy and lymphoma/thymoma, in which Tax was detected, were observed in HTLV-1-infected mice, several months after HTLV-1 infection. These results demonstrate the potential of the HIS Rag2-/-γc-/- animal model to elucidate the initial steps of the leukemogenic process induced by HTLV-1

Sonic Hedgehog Promotes Tumor Cell Survival by Inhibiting CDON Pro-Apoptotic Activity

International audienceThe Hedgehog signaling is a determinant pathway for tumor progression. However, while inhibition of the Hedgehog canonical pathway-Patched-Smoothened-Gli-has proved efficient in human tumors with activating mutations in this pathway, recent clinical data have failed to show any benefit in other cancers, even though Sonic Hedgehog (SHH) expression is detected in these cancers. Cell-adhesion molecule-related/down-regulated by Oncogenes (CDON), a positive regulator of skeletal muscle development, was recently identified as a receptor for SHH. We show here that CDON behaves as a SHH dependence receptor: it actively triggers apoptosis in the absence of SHH. The pro-apoptotic activity of unbound CDON requires a proteolytic cleavage in its intracellular domain, allowing the recruitment and activation of caspase-9. We show that by inducing apoptosis in settings of SHH limitation, CDON expression constrains tumor progression, and as such, decreased CDON expression observed in a large fraction of human colorectal cancer is associated in mice with intestinal tumor progression. Reciprocally, we propose that the SHH expression, detected in human cancers and previously considered as a mechanism for activation of the canonical pathway in an autocrine or paracrine manner, actually provides a selective tumor growth advantage by blocking CDON-induced apoptosis. In support of this notion, we present the preclinical demonstration that interference with the SHH-CDON interaction triggers a CDON-dependent apoptosis in vitro and tumor growth inhibition in vivo. The latter observation qualifies CDON as a relevant alternative target for anticancer therapy in SHH-expressing tumors

Cooperation Between the Thyroid Hormone Receptor TR alpha 1 and the WNT Pathway in the Induction of Intestinal Tumorigenesis

International audienceBACKGROUND & AIMS: Colorectal tumorigenesis is a multistep process involving the alteration of oncogenes and tumor suppressor genes, leading to the deregulation of molecular pathways that govern intestinal homeostasis. We have previously shown that the thyroid hormone receptor alpha 1 (TR alpha 1) controls intestinal development and homeostasis through the WNT pathway. More precisely, TR alpha 1 directly enhances the transcription of several components of this pathway, allowing increased expression of beta-catenin/Tcf4 target genes and stimulation of cell proliferation. Because the WNT pathway is a major player in controlling intestinal homeostasis, we addressed whether the TR alpha 1 receptor has tumor-inducing potential. Methods: We generated mice overexpressing TR alpha 1 specifically in the intestinal epithelium in a wild-type (vil-TR alpha 1) or a WNT-activated (vil-TR alpha 1/Apc(+/1638N)) genetic background. RESULTS: The intestine of vil-TR alpha 1 mice presents aberrant intestinal mucosal architecture and increased cell proliferation and develops adenoma at a low rate. However, TR alpha 1 overexpression is unable to induce cancer development. On the contrary, we observed accelerated tumorigenesis in vil-TR alpha 1/Apc(+/1638N) mice compared with the Apc(+/1638N) mutants. CONCLUSION: Our results suggest that this phenotype is due to cooperation between the activated TR alpha 1 and WNT pathways. This is the first report describing the tumor-inducing function of TR alpha 1 in the intestine

Lipoic acid decreases breast cancer cell proliferation by inhibiting IGF-1R via furin downregulation

International audienceAbstract Background Breast cancer is the second most common cancer in the world. Despite advances in therapies, the mechanisms of resistance remain the underlying cause of morbidity and mortality. Lipoic acid (LA) is an antioxidant and essential cofactor in oxidative metabolism. Its potential therapeutic effects have been well documented, but its mechanisms of action (MOA) are not fully understood. Methods The aim of this study is to validate the inhibitory LA effect on the proliferation of various breast cancer cell lines and to investigate the MOA that may be involved in this process. We tested LA effects by ex vivo studies on fresh human mammary tumour samples. Results We demonstrate that LA inhibits the proliferation and Akt and ERK signalling pathways of several breast cancer cells. While searching for upstream dysregulations, we discovered the loss of expression of IGF-1R upon exposure to LA. This decrease is due to the downregulation of the convertase, furin, which is implicated in the maturation of IGF-1R. Moreover, ex vivo studies on human tumour samples showed that LA significantly decreases the expression of the proliferation marker Ki67. Conclusion LA exerts its anti-proliferative effect by inhibiting the maturation of IGF-1R via the downregulation of furin

Intratumoural spatial distribution of S100B + folliculostellate cells is associated with proliferation and expression of FSH and ERα in gonadotroph tumours

International audienceAbstract Folliculostellate cells are S100B-expressing cells with numerous functions in the normal anterior pituitary. These cells have also been identified in pituitary neuroendocrine tumours (PitNETs), where their precise role remains elusive. Here, we aimed to build a refined cartography of S100B-expressing cells to characterise their interpatient and intratumoural spatial distribution, and to start identifying their potential functions in PitNETs. High-throughput histological analysis of S100B-stained tumour sections of 54 PitNETs revealed a significant decrease in S100B + cells in PitNETs compared to the normal anterior pituitary. A Ki67 index ≥ 3, a mitosis count > 2/10 per high power fields, and a proliferative status, were all associated with fewer S100B + cells in gonadotroph tumours. Gonadotroph tumours also showed interpatient and intratumoural heterogeneity in the spatial distribution of S100B + cells. The existence of an intratumoural heterogeneity was further confirmed by the incorporation to our spatial analysis of additional markers: Ki67, FSH, LH, ERα and SSTR2. The tumour areas with fewer S100B + cells displayed a higher percentage of Ki67 + cells, whereas strong positive correlations were observed between S100B + , FSH + , and ERα + cells. Such spatial associations suggest that S100B + folliculostellate cells could play a role in gonadotroph tumorigenesis, and may contribute to the maintenance of tumour cells in a low proliferating, FSH + /ERα + differentiated state. Albeit, further in-depth functional studies are required to decipher the mechanisms underlying these spatial associations and to potentially identify a therapeutic use

Non-canonical NOTCH3 signalling limits tumour angiogenesis.

Notch signalling is a causal determinant of cancer and efforts have been made to develop targeted therapies to inhibit the so-called canonical pathway. Here we describe an unexpected pro-apoptotic role of Notch3 in regulating tumour angiogenesis independently of the Notch canonical pathway. The Notch3 ligand Jagged-1 is upregulated in a fraction of human cancer and our data support the view that Jagged-1, produced by cancer cells, is inhibiting the apoptosis induced by the aberrant Notch3 expression in tumour vasculature. We thus present Notch3 as a dependence receptor inducing endothelial cell death while this pro-apoptotic activity is blocked by Jagged-1. Along this line, using Notch3 mutant mice, we demonstrate that tumour growth and angiogenesis are increased when Notch3 is silenced in the stroma. Consequently, we show that the well-documented anti-tumour effect mediated by γ-secretase inhibition is at least in part dependent on the apoptosis triggered by Notch3 in endothelial cells.info:eu-repo/semantics/publishe

Traitement d’un lymphome agressif chez un babouin naturellement infecté par STLV-1

L’infection par le virus T Lymphotrope Humain de Type 1 (HTLV-1) est associée à une lymphoprolifération maligne nommée Leucémie/Lymphome T de l’adulte (ATLL). STLV-1 est l’homologue simien de HTLV-1 et cause aussi des ATLL chez les primates non humains. Au cours du contrôle sanitaire annuel dans notre colonie de Papio anubis naturellement infectés par STLV-1 (n=45), une femelle de 9 ans fut identifiée comme présentant des troubles respiratoires, un amaigrissement prononcé, un nombre de lymphocytes supérieur à 1010/L, des métastases pulmonaires et des lésions de la peau, similaires à celles qui sont observées chez les patients souffrant d’ATLL. Ces symptômes étaient donc évocateurs d’une maladie hématologique provoquée par l’infection à STLV-1. Ce diagnostic fut confirmé par la présence d’une lymphoprolifération massive dans la biopsie d’un ganglion inguinal et par la présence de lymphocytes présentant un noyau typique en "trèfle", caractéristique des cellules ATL, dans les frottis sanguins. Comme chez les patients souffrant d’ATLL, l’animal a reçu une combinaison d’AZT (Combivir) et d’interféron alpha (viraféron, 50 μg/semaine) pendant quatre mois. La charge provirale (PVL) fut mesurée de manière hebdomadaire. En l’absence d’amélioration des symptômes cliniques, et puisque seule une très faible diminution de la charge provirale était observée, l’animal fut euthanasié. Des analyses histologiques furent réalisées et la charge provirale mesurée dans 25 organes différents. Tous les organes lymphoïdes montraient des infiltrats lymphocytaires CD3+, CD25+. D’autre part, des cellules anormales furent trouvées dans les poumons et le foie. Grâce à des techniques d’immunohistochimie, nous avons détecté des cellules positives pour le transactivateur viral Tax dans la rate, les poumons, les ganglions mésentériques, axillaires, inguinaux et lymphatiques. Tous les organes testés en PCR étaient positifs pour le virus. La PVL la plus élevée fut mesurée dans les ganglions lymphatiques, la rate et les poumons. Enfin, l’indice d’oligoclonalité et la diversité clonale ont été analysés dans les cellules mononucléées du sang périphérique au cours du traitement, et dans différents organes obtenus après autopsie. En conclusion, les primates non-humains infectés naturellement par STLV-1 représentent un modèle unique permettant d’étudier la pathogenèse rétrovirale et l’évaluation de nouveaux traitements.Nous remercions l’INSERM, l’Ecole Normale Supérieure de Lyon, la Ligue Contre le Cancer (programme « équipe labellisée »), l’Association pour la Recherche sur le Cancer et la région Rhône Alpes programme ARC1