Integrative approach for differentially overexpressed genes in gastric cancer by combining large-scale gene expression profiling and network analysis

Gene expression profiling is a valuable tool for identifying differentially expressed genes in studies of disease subtype and patient outcome for various cancers. However, it remains difficult to assign biological significance to the vast number of genes. There is an increasing awareness of gene expression profile as an important part of the contextual molecular network at play in complex biological processes such as cancer initiation and progression. This study analysed the transcriptional profiles commonly activated at different stages of gastric cancers using an integrated approach combining gene expression profiling of 222 human tissues and gene regulatory dynamic mapping. We focused on an inferred core network with CDKN1A (p21WAF1/CIP1) as the hub, and extracted seven candidates for gastric carcinogenesis (MMP7, SPARC, SOD2, INHBA, IGFBP7, NEK6, LUM). They were classified into two groups based on the correlation between expression level and stage. The seven genes were commonly activated and their expression levels tended to increase as disease progressed. NEK6 and INHBA are particularly promising candidate genes overexpressed at the protein level, as confirmed by immunohistochemistry and western blotting. This integrated approach could help to identify candidate players in gastric carcinogenesis and progression. These genes are potential markers of gastric cancer regardless of stage

Keratan sulphate in the tumour environment

Keratan sulphate (KS) is a bioactive glycosaminoglycan (GAG) of some complexity composed of the repeat disaccharide D-galactose β1→4 glycosidically linked to N-acetyl glucosamine. During the biosynthesis of KS, a family of glycosyltransferase and sulphotransferase enzymes act sequentially and in a coordinated fashion to add D-galactose (D-Gal) then N-acetyl glucosamine (GlcNAc) to a GlcNAc acceptor residue at the reducing terminus of a nascent KS chain to effect chain elongation. D-Gal and GlcNAc can both undergo sulphation at C6 but this occurs more frequently on GlcNAc than D-Gal. Sulphation along the developing KS chain is not uniform and contains regions of variable length where no sulphation occurs, regions which are monosulphated mainly on GlcNAc and further regions of high sulphation where both of the repeat disaccharides are sulphated. Each of these respective regions in the KS chain can be of variable length leading to KS complexity in terms of chain length and charge localization along the KS chain. Like other GAGs, it is these variably sulphated regions in KS which define its interactive properties with ligands such as growth factors, morphogens and cytokines and which determine the functional properties of tissues containing KS. Further adding to KS complexity is the identification of three different linkage structures in KS to asparagine (N-linked) or to threonine or serine residues (O-linked) in proteoglycan core proteins which has allowed the categorization of KS into three types, namely KS-I (corneal KS, N-linked), KS-II (skeletal KS, O-linked) or KS-III (brain KS, O-linked). KS-I to -III are also subject to variable addition of L-fucose and sialic acid groups. Furthermore, the GlcNAc residues of some members of the mucin-like glycoprotein family can also act as acceptor molecules for the addition of D-Gal and GlcNAc residues which can also be sulphated leading to small low sulphation glycoforms of KS. These differ from the more heavily sulphated KS chains found on proteoglycans. Like other GAGs, KS has evolved molecular recognition and information transfer properties over hundreds of millions of years of vertebrate and invertebrate evolution which equips them with cell mediatory properties in normal cellular processes and in aberrant pathological situations such as in tumourogenesis. Two KS-proteoglycans in particular, podocalyxin and lumican, are cell membrane, intracellular or stromal tissue–associated components with roles in the promotion or regulation of tumour development, mucin-like KS glycoproteins may also contribute to tumourogenesis. A greater understanding of the biology of KS may allow better methodology to be developed to more effectively combat tumourogenic processes

ETUDE PAR ELLIPSOMETRIE EN TEMPS REEL D'ANODISATIONS PLASMA DE SILICIUM MONOCRISTALLIN

Un ellipsomètre monochromatique (632.8 nm.) à analyseur tournant a été utilisé pour suivre en temps réel l'oxydation anodique du silicium dans un plasma d oxygène (13.56 MHz, 600 W, 4 Pa). Un modèle comportant une seule couche transparente homogène sur du silicium monocristallin avec une interface abrupte n'est pas suffisant pour expliquer les résultats expérimentaux ; la présence d'une couche interfaciale entre le silicium et la silice est examinée.A monochromatic (632.8 nm) rotating analyzer ellipsometer has been developed for real time analysis of the anodic oxidation of silicon in an oxygen plasma (13.56 MHz, 600 W, 4 Pa). A single transparent layer on crystalline silicon with an abrupt interface cannot explain the experimental results ; the presence of a silicon-silicon dioxide interfacial layer is discussed

TGFβ and hypoxia regulate glycosaminoglycan synthesis and UDP-glucose dehyrogenase activity via SP1 elements.

21-26 septembr

CMOS 1 MICRON ISOLATION TECHNOLOGY USING INTERFACE SEALING BY PLASMA NITRIDATION : PLASMA SILO

Nous avons évalué l'apport de la technique d'isolation par SILO PLASMA dans une filière CMOS 1 µm par comparaison à un isolement par LOCOS classique. Le SILO PLASMA permet de réduire de 0.4 µm les pertes liées au LOCOS, ainsi que l'effet de canal étroit, tout en conservant les principales caractéristiques électriques de cette technique (courant sous le seuil, intégrité de l'oxyde grille, etc.)The improvement of a 1 µm CMOS process using PLASMA SILO as an isolation technique has been evaluated by comparison with a classical LOCOS. The PLASMA SILO provides a reduction of 0.4 µm in the channel width loss, and a gain on the narrow channel effect. The other electrical characteristics are maintained (subthreshold characteristics, gate oxide integrity, etc.

Extracellular matrix protein, lumican inhibits melanoma growth by induction of apoptosis

26-29 Avri

CMOS TECHNOLOGY USING PLASMA NITRIDED OXIDE AS A GATE DIELECTRIC

Une nouvelle technique de nitruration plasma d'oxyde a été développée pour les isolants de grille très minces. Les propriétés d'interface sont conservées après nitruration en plasma d'ammoniac à 950°C. Un excellent comportement des transistors à grille nitrurée lors d'expériences de vieillissement a été relevé ; l'absence de défauts dus au plasma illustrée par les rendements de mémoires SRAM indique la compatibilité du procédé avec la production.A new technique of plasma nitriding oxide has been developed for very thin gate insulators. The interfacial properties are preserved after plasma nitridation in ammonia at 950°C. Excellent behaviour is observed during aging experiments on transistors using nitrided oxide as the dielectric gate ; the absence of defects due to the plasma as illustrated by the yield achieved for SRAM memories suggests the process compatibility with production

Le lumicanne inhibe la croissance du melanome murin.

12-13 jui