References of "Fettweis, Grégory"
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See detailCharacterization of chemotherapy-induced cell death in glioblastoma
Coupienne, Isabelle ULg; Fettweis, Grégory ULg; Piette, Jacques ULg

Poster (2012, December 10)

Glioblastoma constitute the most frequent and deadliest type of brain tumors. Their annual incidence is estimated between 5 and 8 cases per 100,000 people in Europe and North America. They are resistant ... [more ▼]

Glioblastoma constitute the most frequent and deadliest type of brain tumors. Their annual incidence is estimated between 5 and 8 cases per 100,000 people in Europe and North America. They are resistant to all current therapies and are associated with a very high rate of recurrence. The associated prognosis is generally very poor and most patients die within a year after diagnosis. Unfortunately, despite extensive research and use of multimodality treatments combining surgical resection, chemotherapy and radiotherapy, survival hasn’t really much improved over the last 20 years. Indeed, these tumors were shown to be characterized by a high radio- and chemo-resistance. Glioblastoma cells exhibit overexpression of the anti-apoptotic Bcl-2 family proteins and downregulation of its pro-apoptotic members, high expression of the IAPs (Inhibitors of Apoptosis Proteins) and constitutive activation of the pro-survival NF-κB pathway. Currently, the most commonly used treatment offering the best prognosis to patients consists in a combination of maximal surgical tumor resection (when feasible) with subsequent radio- and/or chemotherapy. Among the most commonly used chemotherapeutic agents, the alkylating agent temozolomide and the topoisomerase I inhibitor camptothecin occupy a central position. Therefore, in this study, the impact of both temozolomide and irinotecan (a soluble derivative of camptothecin) on glioma cell survival will be investigated. Important progress was made in the comprehension of the molecular mechanisms underlying tumor development and progression however, survival benefits conferred by the use of new drugs and therapeutic strategies are counted in months rather than years. Consequently, there is an urge to rapidly improve the efficiency of the currently used treatments. This research project consists in (i) the study of the mechanisms implicated in glioblastoma cell death induced by two chemotherapeutic agents : temozolomide and irinotecan, (ii) the identification of the mechanisms underlying the resistance of glioblastoma to these treatments, (iii) the use of pharmacological tools to interfere with those resistance strategies to enhance chemotherapy efficiency. Necrosis was, until recently, long thought to be only accidental. However, it was shown to be finely regulated by specific signalling pathways. Programmed necrosis often takes place in cells in which apoptosis cannot be properly activated and serves as a back-up cell death pathway. Previous work from our lab having already demonstrated that glioblastoma are, at least partially, apoptosis-defective, special emphasis is put on the study of necrotic parameters. Results from survival tests performed on several glioblastoma cell lines in the presence of necrotic inhibitors like necrostatin-1 (an inhibitor of the central regulator of the necrotic pathway RIP1) allows to partially overcome temozolomide and irinotecan-induced glioblastoma cell death, highlighting the role played by programmed necrosis in chemotherapy sensitivity. [less ▲]

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See detailRôle de RIPK3 dans la mort induite par la thérapie photodynamique
Fettweis, Grégory ULg

Master's dissertation (2011)

La protéine RIPK3 (Receptor-interacting protein 3) a été montrée comme étant un activateur clé de la nécrose, mais il a également été constaté qu’il pouvait induire l’apoptose. L’objectif de cette étude ... [more ▼]

La protéine RIPK3 (Receptor-interacting protein 3) a été montrée comme étant un activateur clé de la nécrose, mais il a également été constaté qu’il pouvait induire l’apoptose. L’objectif de cette étude est de comparer le profil de la mort induite par la thérapie photodynamique (PDT) médiée par l’acide 5-aminolévulinique (5-ALA) dans la lignée U2OS déficiente en RIPK3 et dans des U2OS où l’expression de RIPK3 était restaurée de manière stable. Pour ce faire, nous avons évalué la survie cellulaire ainsi que les paramètres d’apoptose, de nécrose et d’autophagie. De manière surprenante, la survie des U2OS RIPK3 positives traitées par 5-ALA-PDT a été augmentée comparé aux U2OS sauvages. De plus, la mort des cellules RIPK3 positives était diminuée lors d’un prétraitement au zVAD-fmk. Un clivage plus important de PARP et des caspase-3, -7, -8 et -9 a été constaté dans les cellules contenant RIPK3, pointant le rôle essentiel de l’apoptose dans la mort induite par 5-ALA-PDT. En parallèle, nous avons observé une augmentation du flux autophagique et de manière surprenante, un plus faible niveau de nécrose que dans les cellules U2OS Wild types. De plus, la nécrose induite en présence de RIPK3 était dépendante de RIPK1 au contraire de la nécrose induite dans les cellules U2OS RIP3 négatives. L’expression de RIPK3 a induit un changement de profil de la mort induite par 5-ALA-PDT, mais aussi une meilleure survie cellulaire face à ce traitement. Cet accroissement de la survie, dont l’observation constitue une première pourrait être dû au flux autophagique augmenté en présence de RIPK3. Enfin, le biais par lequel RIPK3 sensibilise les cellules à l’apoptose, et le mécanisme régissant la nécrose induite en absence de RIPK3 par la 5-ALA-PDT ne sont pas encore connus. [less ▲]

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See detailRIP3 Expression Induces a Death Profile Change in U2OS Osteosarcoma Cells After 5-ALA-PDT
Coupienne, Isabelle ULg; Fettweis, Grégory ULg; Piette, Jacques ULg

in Lasers in Surgery and Medicine (2011), 43(7), 557564

Background and Objective The receptor-interacting protein 3 (RIP3) has recently been outlined as a key necrosis mediator but is also thought to participate in the regulation of apoptosis. The aim of this ... [more ▼]

Background and Objective The receptor-interacting protein 3 (RIP3) has recently been outlined as a key necrosis mediator but is also thought to participate in the regulation of apoptosis. The aim of this study is to compare the cell death profile induced by 5-aminolevulic acid (5-ALA)-mediated photodynamic therapy (PDT) in the RIP3-deficient cell line U2OS and in U2OS cells in which the expression of RIP3 was restored. Materials and Methods RIP3-expressing U2OS cells (RIP3-U2OS) were obtained after transfection and antibiotic selection. Wild type and RIP3-U2OS cells were treated by 5-ALA-PDT. Overall cell viability was evaluated and different parameters characteristic of apoptosis, autophagy, and necrosis were studied. Results Surprisingly, the survival of RIP3-U2OS cells was higher compared to that of the wild type cells. In addition, RIP3-U2OS cell death was decreased by a zVAD-fmk pre-treatment. A higher cleavage of caspase-3, 7, 8, 9, and PARP was also detected in these cells, pointing out to the activation of caspase-dependent apoptosis. In parallel, a thrust of autophagy was clearly identified in the RIP3-U2OS cells. Conversely, RIP3-U2OS exhibited a lower level of necrosis than the wild types. Interestingly, necrostatin-1 efficiently decreased necrosis level in RIP3-U2OS but not in wild type cells. Conclusion Expression of RIP3 in U2OS cells led to a better survival but also to a death profile change in response to PDT. The apoptotic and autophagic pathways were clearly up-regulated compared to the RIP3-deficient wild type cells. However, induction of necrosis was weaker in the RIP3-U2OS cells. In this context, autophagy is likely to play a protective role against PDT-induced cell death and to allow a better survival of RIP3-U2OS cells. This work also highlights the important role played by RIP3 in the apoptotic pathway, although the modalities are still widely unknown. [less ▲]

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See detailStudy of the combined effect of 5-ALA-based photodynamic therapy and NF-kappaB inhibition on human glioblastoma cell survival
Coupienne, Isabelle ULg; Fettweis, Grégory ULg; Piette, Jacques ULg

Poster (2011, January)

Glioblastoma constitute the most frequent and deadliest type of brain tumors in human adults. They are very resistant to all current therapies and are associated with a huge rate of recurrence. In most ... [more ▼]

Glioblastoma constitute the most frequent and deadliest type of brain tumors in human adults. They are very resistant to all current therapies and are associated with a huge rate of recurrence. In most cases, this type of tumor is characterized by a constitutive activation of the nuclear factor-kappaB (NF-kappaB). This factor is known to be a key regulator of various physiological processes such as inflammation, immune response, cell growth or apoptosis. In the present study, we explored the role of NF-kappaB activation in the sensitivity of human glioblastoma cells to a treatment by 5-aminolevulinic acid (5-ALA)–based photodynamic therapy (PDT). Our results show that inhibition of NF-kappaB improves glioblastoma cell death in response to 5-ALA-PDT. We then studied the molecular mechanisms underlying the cell death induced by PDT combined or not with NF-kappaB inhibition. We found that PDT mainly induced necrosis in glioblastoma cells and NF-kappaB was found to have anti-necrotic functions in this context. In the second part of this study, we examined the role of the kinase RIP3, recently identified as a key effector of the necrotic pathway, in 5-ALA-PDT-induced necrosis and studied whether NF-kappaB interfered in RIP3-dependent necrosis induction. [less ▲]

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See detail5-ALA-PDT induces RIP3-dependent necrosis in glioblastoma
Coupienne, Isabelle ULg; Fettweis, Grégory ULg; Rubio-Romero, Noemi ULg et al

in Photochemical & Photobiological Sciences (2011)

Glioblastoma constitute the most frequent and deadliest brain tumors of astrocytic origin. They are resistant to all current therapies and are associated with a high rate of recurrence. Glioblastoma were ... [more ▼]

Glioblastoma constitute the most frequent and deadliest brain tumors of astrocytic origin. They are resistant to all current therapies and are associated with a high rate of recurrence. Glioblastoma were previously shown to respond to treatments by 5-aminolevulinic acid (5-ALA)-based photodynamic therapy (PDT) mainly by activating a necrotic type of cell death. The receptor-interacting protein 3 (RIP3) has recently been outlined as a key mediator of this caspase-independent form of programmed cell death. In the present study, we analyzed the necrotic mechanism induced by 5-ALA-PDT in human glioblastoma cells and explored the role of RIP3 in this context. Our results show that PDT-induced necrosis is dependent on RIP3, which forms aggregates and colocalizes with RIP1 following photosensitization. We demonstrate that PDT-mediated singlet oxygen production is the cause of RIP3-dependent necrotic pathway activation. We also prove that PDT induces the formation of a pro-necrotic complex containing RIP3 and RIP1 but lacking caspase-8 and FADD, two proteins usually part of the necrosome when TNF-α is used as a stimulus. Thus, we hypothesize that PDT might lead to the formation of a different necrosome whose components, besides RIP1 and RIP3, are still unknown. In most cases, glioblastoma are characterized by a constitutive activation of NF-κB. This factor is a key regulator of various processes, such as inflammation, immune response, cell growth or apoptosis. Its inhibition was shown to further sensitize glioblastoma cells to PDT-induced necrosis, however, no difference in RIP3 upshift or aggregation could be observed when NF-κB was inhibited. [less ▲]

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