WIF1 re-expression in glioblastoma inhibits migration through attenuation of non-canonical WNT signaling by downregulating the lncRNA MALAT1.

Glioblastoma is the most aggressive primary brain tumor in adults and due to the invasive nature cannot be completely removed. The WNT inhibitory factor 1 (WIF1), a secreted inhibitor of WNTs, is systematically downregulated in glioblastoma and acts as strong tumor suppressor. The aim of this study was the dissection of WIF1-associated tumor-suppressing effects mediated by canonical and non-canonical WNT signaling. We found that WIF1 besides inhibiting the canonical WNT pathway selectively downregulates the WNT/calcium pathway associated with significant reduction of p38-MAPK (p38-mitogen-activated protein kinase) phosphorylation. Knockdown of WNT5A, the only WNT ligand overexpressed in glioblastoma, phenocopied this inhibitory effect. WIF1 expression inhibited cell migration in vitro and in an orthotopic brain tumor model, in accordance with the known regulatory function of the WNT/Ca(2+) pathway on migration and invasion. In search of a mediator for this function differential gene expression profiles of WIF1-expressing cells were performed. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a long non-coding RNA and key positive regulator of invasion, emerged as the top downregulated gene. Indeed, knockdown of MALAT1 reduced migration in glioblastoma cells, without effect on proliferation. Hence, loss of WIF1 enhances the migratory potential of glioblastoma through WNT5A that activates the WNT/Ca(2+) pathway and MALAT1. These data suggest the involvement of canonical and non-canonical WNT pathways in glioblastoma promoting key features associated with this deadly disease, proliferation on one hand and invasion on the other. Successful targeting will require a dual strategy affecting both canonical and non-canonical WNT pathways

Investigating the role of HIV-1 Tat Interactive Protein 2 (HTATIP2) in glioblastoma

Glioblastoma (GBM) is the most frequent and malignant of all primary brain tumors. Although a lot is known about the disease at a genetic and molecular level, the new era of epigenome analysis has revealed useful and interesting information about the disease that was not known to us before. A genome wide methylation analysis of GBM patients has directed us to a number of new genes with a potential rôle in the development of GBM. HIV-1 Tat Interactive protein 2 (HTATIP2), is one such gene whose promoter was found to be differentially methylated in GBM patients, thereby down-regulating its expression at an epigenetic level. HTATIP2 is an oxido-reductase shown to regulate trafficking and nuclear entry of some major cellular proteins, including Epidermal Growth Factor Receptor (EGFR). HTATIP2 is involved in tumor metastasis suppression in hepatocellular carcinoma, variant small cell lung cancer and ovarian cancer and has also shown to enhance tumorigenesis in HTATIP2 knock-out mice. The presence of EGFR and its functions in the nucleus, although debated in GBM, has been well established in other cancer types with HTATIP2 playing a vital rôle in the trafficking process. In this thesis, we have explored the functions of HTATIP2 in GBM using in-vitro models. By over-expressing HTATIP2 in epigenetically down-regulated cell lines (LN-18, LN- 229, and BS-153) and by siRNA mediated gene-silencing of HTATIP2 in endogenously expressing lines (LN-428), we have attempted to study some of the specific tumor suppressive functions of HTATIP2. We have been able to show in our cell lines that HTATIP2 does not play a rôle in influencing growth and prolifération. We have neither observed a faster proteolytic dégradation of EGFR in our cells over-expressing HTATIP2. However, we were able to successfully provide a novel link between HTATIP2 and an increased cytoplasmic rétention of the DNA base excision repair enzyme, N- Methylpurine DNA glycosylase (MPG). MPG has been recently shown to provide résistance to TMZ induced DNA damage in GBM patients and a higher expression of MPG significantly reduces overall survival in patients treated with Temozolomide (TMZ). With MPG's DNA repair rôle gaining more focus in treatment résistance in GBM, our in-vitro experiments provide evidences to a novel mechanism linking MPG cellular localization and HTATIP2 expression. Our preliminary rétrospective data analysis on a small number of GBM patients, show à corrélation between HTATIP2 expression and MPG cellular localization. Our findings provide evidences that HTATIP2 by blocking MPG nuclear entry holds an important rôle in-vitro, which is being further verified and validated in GBM samples. -- Le glioblastome (GBM) est la plus fréquente et la plus maligne des tumeurs cérébrales primaires. Bien que d'importants aspects moléculaires et génétiques soient déjà connus, les récents progrès dans le domaine de l'épigénétique ouvrent de nouvelles perspectives dans la compréhension de cette maladie. L'analyse génomique de la méthylation dans le GBM a permis de découvrir une série de nouveaux gènes potentiellement impliqués dans le développement du GBM. HTATIP2 ou HIV-1 Tat Interactive protein-2 est un de ces gènes dont le promoteur est différemment méthylé chez les patients atteints de GBM et l'expression régulée au niveau épigénétique. HTATIP2 est une protéine de type oxido-réductase dont la forme liée NADP joue un rôle dans les échanges et l'entrée dans le noyau d'importantes protéines cellulaires dont l'Epidermal Growth Factor Receptor (EGFR). HTATIP2 est impliqué dans le cancer du foie, du poumon et des ovaires à travers son rôle de suppresseur de métastase. Il est aussi connu comme promoteur de la tumorigénèse dans un modèle de souris knock-out. L'EGFR et ses fonctions dans le noyau cellulaire bien que controversés dans le GBM sont bien établis dans d'autres cancers, HTATIP2 y jouant un rôle majeur. Dans cette thèse, nous avons étudié les fonctions possibles d' HTATIP2 dans le GBM en utilisant un modèle in vitro. En faisant sur exprimer HTATIP2 dans 3 lignées de GBM (LN-18, LN-229. BS-153) et en utilisant une technique de siRNA mediated gene-silencing dans la LN-428, lignée exprimant naturellement HTATIP2, nous avons pu étudier certaines des fonctions de suppression tumorale d' HTATIP2. Nous avons pu démontrer que dans les lignées étudiées, HTATIP2 n'influence ni la croissance, ni la prolifération cellulaire. Nous n'avons pas non plus observé une augmentation de la dégradation protéolytique de l'EGFR dans les cellules sur exprimant HTATIP2. Néanmoins, nous avons pu démontrer un lien entre HTATIP2 et une augmentation de la rétention cytoplasmique du N-Methylpurine DNA glycolsylase (MPG), une enzyme de réparation de l'ADN Le rôle de MPG dans la résistance au traitement de temozolomide (TMZ) a récemment été démontré ainsi qu'une expression augmentée de MPG qui réduirait la survie des patients atteints de glioblastome, traités au TMZ . Face à l'intérêt grandissant du rôle de MPG dans la résistance au traitement et dans le pronostic du GBM, nos expériences in vitro offre un lien nouveau entre la localisation cellulaire de MPG et l'expression de HTATIP2. Notre data analyse rétrospective concernant un petit nombre de patients atteints de glioblastome montre une corrélation entre l'expression de HTATIP2 et la localisation cellulaire du MPG. Nos expériences contribuent à démontrer qu' HTATIP2 en bloquant l'entrée du MPG dans le noyau, joue un rôle dans le mécanisme de suppression tumorale. Ce qui nous sommes en train de vérifier et confirmer grâce à un nouveau set de GBM

Efficient catalyst for tandem solvent free enantioselective Knoevenagel-formal [3+3] cycloaddition and Knoevenagel-hetero-Diels-Alder reactions

In this study a highly efficient catalyst has been observed for tandem solvent free enantioselective Knoevenagel-formal [3+3] cycloaddition and Knoevenagel-hetero-Diels-Alder reactions. Thus, the synthesis of bicyclic tetrahydro-2H-chromen-5(6H)-one and tricyclic octahydro-2H-benzo[c]-chromen-1(6H)-one derivatives with enantioselectivity up to ee 99% has been achieved in the presence of a chiral Lewis acid assisted Bronsted acid (LBA), titanium-isopropoxy-(S)-BINOLate under solvent free conditions. The stereochemistry of the tricyclic product 10 has been further supported by single crystal X-ray analysis. This domino powerful strategy combines both the economic and environmental aspects of organic chemistry, which are necessary for academic and industrial applications

meso-Salicylaldehyde substituted BODIPY as a chemodosimetric sensor for cyanide anions

The meso-salicylaldehyde substituted BODIPY was synthesized over a sequence of steps and characterized by X-ray crystallography, mass, NMR, absorption, fluorescence and electrochemical techniques. The crystal structure showed the presence of strong intramolecular hydrogen bonding between hydroxyl and formyl groups, which induces rigidity in the BODIPY core and makes the BODIPY relatively more fluorescent than the meso-phenyl BODIPY. Our studies showed that the meso-salicylaldehyde BODIPY can be used as a specific chemidosimetric sensor for CN- ions. The presence of a hydroxyl group adjacent to a formyl group helps in activating the formyl group for a nucleophilic attack. Upon addition of the CN- ion to the meso-salicylaldehyde BODIPY, the CN- ion attacks the formyl group and converts it to the cyanohydrin group. This irreversible reaction was monitored by following the changes in absorption, fluorescence and electrochemical properties and the results support the view that the meso-salicylaldehyde substituted BODIPY can be used as a specific chemodosimetric sensor for CN- ions. To substantiate the role of the hydroxyl group, we also prepared the meso(m-formylphenyl) BODIPY which contains only the formyl group on meso-phenyl, and our studies indicated that the meso(m-formylphenyl) BODIPY cannot be used as a chemodosimetric sensor for CN- ions, as verified by absorption and emission studies

Auxiliary ligand-aided tuning of aggregation of transition metal benzoates: isolation of four different types of coordination polymers

Reactions of alkyl-substituted aromatic monocarboxylic acids with first-row transition metal ions in the presence of chelating and bridging N, N-donor ligands produce a variety of discrete and polymeric complexes, depending on the position of the substituent on benzoic acid and the ability of the auxiliary ligand to act as a chelating or a bridging ligand. The eleven different compounds isolated in the present study fall into two different structural types, viz., discrete mono or/dinuclear complexes ([Cu(L-1)(2)(AL(1))(H2O)] (1), [Mn(L-1)(2)(AL(1))](2) (2) and [Zn(L-1)(2)(AL(1))](2) (3)) and polymeric compounds (4-11). The polymeric compounds isolated can further be classified into four different structural types, viz., 1D helical polymers, linear 1D polymeric chains, railroad-like polymers and 2D polymeric sheets. The structure modulation is a result of the combination of the types of substituents on the aryl ring of the benzoic acid and the nature of the auxiliary ligand used. For example, when 1,10-phenanthroline was used as the auxiliary ligand and the carboxylic acid used was 4-tert-butylbenzoic acid, discrete complexes were isolated. However, for the same auxiliary ligand, when 2,4,6-trimethylbenzoic acid was used, a series of 1D helical polymers ([M(L-2)(2)(AL(1))(H2O)](n); M = Mn (4), Co (5), Cu (6), and Zn (7)) were obtained. This clearly demonstrates the ability of o, o'-disubstituted benzoic acids to form helical polymers, whereas p-substitution on the aryl ring results in discrete complexes. The reactions of metal acetates with benzoic acid in the presence of 4,4'-bipyridine were found to be sensitive to the ortho substituents on the acid. When two equivalents of 2,4,6-triisopropylbenzoic acid were used, a linear polymer ([Zn(L-3)(2)(AL(2))](n) (8)) was obtained. The use of either one or two equivalents of 2,4,6-trimethyl benzoic acid invariably leads to the isolation of railroad-like polymers ([M(L-2)(OAc)(AL(2))](n); M = Mn (9) and Zn (10)) where the rails are bridged by the acetate ligand. Replacing the carboxylic acid by a phosphate diester leads to the isolation of a 2D polymer ([Zn(L-4)(2)(AL(2))](n) (11)) due to the ability of phosphate to act exclusively as a bridging ligand. In addition to extensive analytical and spectroscopic characterization of the products, the solid-state structures of all the new compounds were determined using single-crystal X-ray diffraction

Synthesis and Crystal Structure of the Rhenium(I) Tricarbonyl Complex of 5,10,15,20-Tetra-p-tolyl-21,23-dithiaporphyrin

The hexacoordinated rhenium(I) complex of 5,10,15,20-tetra-p-tolyl-21,23-dithiaporphyrin was synthesized, and the crystal structure analysis revealed the unusual binding mode of rhenium(I) to two thiophene sulfur atoms and one of the pyrrole nitrogen atoms of the porphyrin macrocycle

Stereochemical modulation of emission behaviour in E/Z isomers of diphenyldipyrroethene from aggregation induced emission to crystallization induced emission

Herein, we report the synthesis, separation and characterisation of the E- and Z-isomers of dipyrrolyldiphenylethene to study their emission behaviour in the aggregation state and solid state. The E-isomer showed pronounced Aggregation Induced Emission (AIE) whereas the Z-isomer showed Crystallization Induced Emission (CIE). The present study explains that the emission behaviour (AIE/CIE) is dependent on the inter/intra molecular interactions between the molecules. The study also confirms that Restriction of Intramolecular Rotation (RIR) is the main cause of AIE/CIE in olefinic luminogens Tetraphenylethylene (TPE) type systems rather than E/Z isomerisation