Radiorésistance de lignées cellulaires humaines de gliobastomes : recherche de bloqueurs par métabolomique, lipidomique et transcriptomique

Les glioblastomes (GBM) sont les tumeurs cérébrales humaines les plus agressives. Les personnes atteintes de cette maladie meurent généralement dans l'année suivant le diagnostic. La radiothérapie, qui est de plus en plus utilisée en présence d'un agent radiosensibilisant, est systématiquement appliquée afin de diminuer la progression tumorale. Néanmoins, elle se heurte au phénomène de radiorésistance. Afin de proposer dans un avenir proche une thérapie adaptée à chaque patient, une classification moléculaire des GBM est en train de naître. Celle-ci tient notamment compte d'un biomarqueur prédictif de chimiorésistance, mais non de radiorésistance. Dans ce contexte, nous avons cherché, dans un premier temps, à identifier in vitro de potentiels biomarqueurs de radiorésistance dans quatre lignées cellulaires humaines de GBM de radiosensibilité différente. Pour cela, nous avons eu recours à des méthodes analytiques holistiques et robustes telles que la RMN 1H métabolomique, la lipidomique et la transcriptomique. Une accumulation de composés à choline dans les deux lignées les plus radiorésistantes a ainsi été mise en évidence. Une méthode d'analyse du métabolisme des phosphatidylcholines par marquage deutéré et quantification par HILIC-ESI-MS/MS a été mise au point afin de confirmer ces résultats. Dans une seconde partie, nous avons cherché à identifier in vitro de potentiels biomarqueurs de mort radio-induite dans des lignées cellulaires humaines de GBM radiosensibilisées. La RMN 1H métabolomique a été privilégiée pour cette investigation et complétée par des études lipidomique et de mort cellulaire par cytométrie en flux pour l'un des projets. La taurine a ainsi été identifiée comme potentiel biomarqueur de mort cellulaire.Glioblastomas (GBM) are the most aggressive human brain tumors. Indeed, patients most often die within the year after the diagnostic. Radiotherapy generally associated to radiosensitizers is currently systematically used to reduce tumor progression. Nevertheless, a radioresistance phenomenon still occurs. An individual treatment is hoped for each patient. For this purpose, a molecular classification of GBM has been created, taking into account biomarkers such as a predictive chimioresistance factor, but not radioresistance one. In this context, we have searched for in vitro radioresistance biomarkers in four human GBM cell lines with different radiosensitivity profiles. This corresponds to the first part of the PhD manuscript. Comprehensive and robust analytical methods such as 1H NMR metabolomics, lipidomics and transcriptomics have been used. An accumulation of choline compounds has been observed in the two more radioresistant cell lines. An analytical method using deuterated labelling and HILIC-ESI-MS/MS has been developed to study the metabolism of phosphatidylcholines in the four cell lines. In the second part of the PhD project, we have focused on potential in vitro biomarkers of radio-induced cell death in radiosensitized human GBM cell lines. For this, NMR 1H metabolomics has been chosen. Taurine has been found as a good candidate in a cell line. Lipidomics and FACS analyses have then been used to confirm this result

Marine Antimalarials

Malaria is an infectious disease causing at least 1 million deaths per year, and, unfortunately, the chemical entities available to treat malaria are still too limited. In this review we highlight the contribution of marine chemistry in the field of antimalarial research by reporting the most important results obtained until the beginning of 2009, with particular emphasis on recent discoveries. About 60 secondary metabolites produced by marine organisms have been grouped into three structural types and discussed in terms of their reported antimalarial activities. The major groups of metabolites include isonitrile derivatives, alkaloids and endoperoxide derivatives. The following discussion evidences that antimalarial marine molecules can efficiently integrate the panel of lead compounds isolated from terrestrial sources with new chemical backbones and, sometimes, with unique functional groups

Antiplasmodial Activities of Homogentisic Acid Derivative Protein Kinase Inhibitors Isolated from a Vanuatu Marine Sponge Pseudoceratina sp.

As part of our search for new antimalarial drugs in South Pacific marine sponges, we have looked for inhibitors of Pfnek-1, a specific protein kinase of Plasmodium falciparum. On the basis of promising activity in a preliminary screening, the ethanolic crude extract of a new species of Pseudoceratina collected in Vanuatu was selected for further investigation. A bioassay-guided fractionation led to the isolation of a derivative of homogentisic acid [methyl (2,4-dibromo-3,6-dihydroxyphenyl)acetate, 4a] which inhibited Pfnek-1 with an IC50 around 1.8 μM. This product was moderately active in vitro against a FcB1 P. falciparum strain (IC50 = 12 μM). From the same sponge, we isolated three known compounds [11,19-dideoxyfistularin-3 (1), 11-deoxyfistularin-3 (2) and dibromo-verongiaquinol (3)] which were inactive against Pfnek-1. Synthesis and biological evaluation of some derivatives of 4a are reported

Radiorésistance de lignées cellulaires humaines de gliobastomes (recherche de bloqueurs par métabolomique, lipidomique et transcriptomiques)

TOULOUSE3-BU Sciences (315552104) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Analysis of adulterated herbal medicines and dietary supplements marketed for weight loss by DOSY 1H NMR

International audienceTwenty herbal medicines or dietary supplements marketed as natural slimming products were analyzed by Diffusion Ordered SpectroscopY (DOSY) 1H NMR and DOSY-COSY 1H NMR. The method allows analysis of the whole sample with detection of both active and inactive ingredients in these complex matrices. Among the 20 formulations analyzed, 2 were strictly herbal and 4 had a composition corresponding to declared ingredients on the packaging or the leaflet. The others were all adulterated. Eight formulations contain sibutramine alone at doses ranging from 4.4 to 30.5 mg/capsule. Five formulations contain sibutramine (from 5.0 to 19.6 mg/capsule or tablet) in combination with phenolphthalein (from 4.4 to 66.1 mg/capsule), and the last formulation was adulterated with synephrine (19.5 mg/capsule). Quantification of the actives was carried out with 1H NMR. Several other compounds were also characterized including methylsynephrine, vitaberin, sugars, vitamins etc. DOSY NMR is thus proposed as a useful tool for detection of unexpected adulteration

Alisiaquinones and alisiaquinol, dual inhibitors of Plasmodium falciparum enzyme targets from a New Caledonian deep water sponge

Four new meroterpenes, alisiaquinones A-C (1-3) and alisiaquinol (4), were isolated from a New Caledonian deep water sponge. Their structures and relative stereochemistry were elucidated by spectroscopic data analysis. They are related to xestoquinone, but showed unusual substitution on a tetrahydrofuran junction. They displayed micromolar range activity on two enzymatic targets of importance for the control of malaria, the plasmodial kinase Pfnek-1 and a protein farnesyl transferase, as well as on different chloroquine-sensitive and -resistant strains of Plasmodium falciparum. Alisiaquinone C displayed a submicromolar activity on P. falciparum and a competitive selectivity index on the different plasmodial strains

Synthesis and antimalarial properties of streptocyanine dyes

Several streptocyanine dyes were synthesized that contain polymethine chains of varying length. Their in vitro antimalarial activities were evaluated against the virulent P. falciparum parasite. In addition to the influence of polymethine chain length, the effects of structural modifications at nitrogen end groups, para substitution of the phenyl groups, and counter-anions were studied. The most potent antimalarial activities were found for heptacarbon chain streptocyanines, with an IC50 value of 60 nM. Interestingly, most of the compounds were less cytotoxic toward the mammalian cells tested. The best selective toxicity profiles were found for pentacarbon chain streptocyanines, which have a good in vitro specificity index