Comparison of Holmium:YAG and Thulium Fiber Lasers on the Risk of Laser Fiber Fracture

Objectives: To compare the risk of laser fiber fracture between Ho:YAG laser and Thulium Fiber Laser (TFL) with different laser fiber diameters, laser settings, and fiber bending radii. METHODS: Lengths of 200, 272, and 365 mu m single use fibers were used with a 30 W Ho:YAG laser and a 50 W Super Pulsed TFL. Laser fibers of 150 mu m length were also tested with the TFL only. Five different increasingly smaller bend radii were tested: 1, 0.9, 0.75, 0.6, and 0.45 cm. A total of 13 different laser settings were tested for the Ho:YAG laser: six fragmentation settings with a short pulse duration, and seven dusting settings with a long pulse duration. A total of 33 different laser settings were tested for the TFL. Three laser settings were common two both lasers: 0.5 J x 12 Hz, 0.8 J x 8 Hz, 2 J x 3 Hz. The laser was activated for 5 min or until fiber fracture. Each measurement was performed ten times. Results: While fiber failures occurred with all fiber diameters with Ho:YAG laser, none were reported with TFL. Identified risk factors of fiber fracture with the Ho:YAG laser were short pulse and high energy for the 365 mu m fibers (p = 0.041), but not for the 200 and 272 mu m fibers (p = 1 and p = 0.43, respectively). High frequency was not a risk factor of fiber fracture. Fiber diameter also seemed to be a risk factor of fracture. The 200 mu m fibers broke more frequently than the 272 and 365 mu m ones (p = 0.039). There was a trend for a higher number of fractures with the 365 mu m fibers compared to the 272 mu m ones, these occurring at a larger bend radius, but this difference was not significant. Conclusion: TFL appears to be a safer laser regarding the risk of fiber fracture than Ho:YAG when used with fibers in a deflected position

Energetic metabolism and anticancer treatments : study of Δ2-troglitazone and 2-deoxyglucose effects on breast cancer cells

L’absence de réponse et la résistance des cellules cancéreuses mammaires aux thérapies actuelles justifient de développer de nouveaux traitements. Une stratégie prometteuse consiste à cibler le métabolisme énergétique des cellules cancéreuses. Dans ce contexte, des thiazolidinediones (TZD) présentent des effets antiprolifératifs qui pourraient résulter d’une atteinte du métabolisme énergétique. Notre laboratoire étudie des TZD dérivées de la troglitazone (TGZ). Durant cette thèse, nous avons cherché à déterminer si la Δ2-Troglitazone (Δ2-TGZ) modifie le métabolisme énergétique des cellules cancéreuses mammaires. Jusqu’à présent, les expériences menées au laboratoire étaient réalisées dans un milieu de culture contenant 1% de sérum de veau fœtal (SVF) qui crée un stress peu propice à l’étude du métabolisme. Nous avons donc d’abord caractérisé les effets de la Δ2-TGZ dans un milieu de culture contenant 10% SVF. Dans ces conditions, la Δ2-TGZ diminue toujours la prolifération des cellules cancéreuses mammaires, mais les doses requises sont plus élevées. En outre, la Δ2-TGZ induit des effets cytostatiques plutôt que l’apoptose. Nous avons ensuite montré que la Δ2-TGZ induit une perturbation du métabolisme énergétique, consistant en un blocage de la respiration mitochondriale que les cellules semblent compenser en stimulant la glycolyse. En parallèle, nous avons caractérisé le mode d’action du 2-désoxyglucose dont l’action antiproliférative dans les cellules cancéreuses mammaires est due à l’inhibition de la glycolyse et à la perturbation de la N-glycosylation des protéines. Il reste à déterminer la part des altérations métaboliques dans l’action anti-cancéreuse de la Δ2-TGZThe absence of response and the resistance of cancer cells to therapies are strong arguments for the development of new therapeutic strategies. Data from the literature suggest that it could be interesting to target energy metabolism of cancer cells. In this context, thiazolidinediones (TZDs) display antiproliferative effects that could be the result of energy metabolism alteration. During this PhD, we aimed at determining if Δ2-Troglitazone (Δ2-TGZ) could modify energy metabolism of breast cancer cells. The experiments performed previously used a culture medium containing 1% of fetal calf serum (FCS) that is rather a stress inducing condition that can disturb cell metabolism. Thus, we first characterized the effects of Δ2-TGZ in a 10% FCS containing medium. In this case, Δ2-TGZ still decreases cell proliferation of breast cancer cells, but it requires high doses. Besides, Δ2-TGZ induces cell cycle arrest instead of apoptosis. Then, we have shown that Δ2-TGZ induced modifications of energy metabolism, which are due to a decrease in oxidative phosphorylation. We also observed an increase in glycolytic activity that is probably a compensatory mechanism. During this part of our work, we have also characterized the mechanisms involved in the anticancer activity of 2-deoxyglucose. We have shown that in breast cancer cells, this compound acts not only by glycolysis inhibition but also by protein N-glycosylation alteration. We have now to determine the part of metabolic alterations that are involved in the anti-cancer effects of Δ2-TG

Métabolisme énergétique et traitements anticancéreux : caractérisation des effets de la Δ2-troglitazone et du 2-désoxyglucose sur les cellules d’adénocarcinomes mammaires

The absence of response and the resistance of cancer cells to therapies are strong arguments for the development of new therapeutic strategies. Data from the literature suggest that it could be interesting to target energy metabolism of cancer cells. In this context, thiazolidinediones (TZDs) display antiproliferative effects that could be the result of energy metabolism alteration. During this PhD, we aimed at determining if Δ2-Troglitazone (Δ2-TGZ) could modify energy metabolism of breast cancer cells. The experiments performed previously used a culture medium containing 1% of fetal calf serum (FCS) that is rather a stress inducing condition that can disturb cell metabolism. Thus, we first characterized the effects of Δ2-TGZ in a 10% FCS containing medium. In this case, Δ2-TGZ still decreases cell proliferation of breast cancer cells, but it requires high doses. Besides, Δ2-TGZ induces cell cycle arrest instead of apoptosis. Then, we have shown that Δ2-TGZ induced modifications of energy metabolism, which are due to a decrease in oxidative phosphorylation. We also observed an increase in glycolytic activity that is probably a compensatory mechanism. During this part of our work, we have also characterized the mechanisms involved in the anticancer activity of 2-deoxyglucose. We have shown that in breast cancer cells, this compound acts not only by glycolysis inhibition but also by protein N-glycosylation alteration. We have now to determine the part of metabolic alterations that are involved in the anti-cancer effects of Δ2-TGZL’absence de réponse et la résistance des cellules cancéreuses mammaires aux thérapies actuelles justifient de développer de nouveaux traitements. Une stratégie prometteuse consiste à cibler le métabolisme énergétique des cellules cancéreuses. Dans ce contexte, des thiazolidinediones (TZD) présentent des effets antiprolifératifs qui pourraient résulter d’une atteinte du métabolisme énergétique. Notre laboratoire étudie des TZD dérivées de la troglitazone (TGZ). Durant cette thèse, nous avons cherché à déterminer si la Δ2-Troglitazone (Δ2-TGZ) modifie le métabolisme énergétique des cellules cancéreuses mammaires. Jusqu’à présent, les expériences menées au laboratoire étaient réalisées dans un milieu de culture contenant 1% de sérum de veau fœtal (SVF) qui crée un stress peu propice à l’étude du métabolisme. Nous avons donc d’abord caractérisé les effets de la Δ2-TGZ dans un milieu de culture contenant 10% SVF. Dans ces conditions, la Δ2-TGZ diminue toujours la prolifération des cellules cancéreuses mammaires, mais les doses requises sont plus élevées. En outre, la Δ2-TGZ induit des effets cytostatiques plutôt que l’apoptose. Nous avons ensuite montré que la Δ2-TGZ induit une perturbation du métabolisme énergétique, consistant en un blocage de la respiration mitochondriale que les cellules semblent compenser en stimulant la glycolyse. En parallèle, nous avons caractérisé le mode d’action du 2-désoxyglucose dont l’action antiproliférative dans les cellules cancéreuses mammaires est due à l’inhibition de la glycolyse et à la perturbation de la N-glycosylation des protéines. Il reste à déterminer la part des altérations métaboliques dans l’action anti-cancéreuse de la Δ2-TG

∆2-Troglitazone and 2-Deoxyglucose inhibit breast cancer cell proliferation: a consequence of the alteration of the cancer cell metabolism?

Présentation PosterNational audienceBackground: Resistance to conventional therapies and the absence of targeted therapy for triple negative mammary tumors are strong arguments for the search for new therapeutic agents. In cancer cells, the dependency on glycolysis for energy generation provides a biochemical basis to preferentially kill the malignant cells by inhibiting glycolysis. Thiazolidinediones display antiproliferative effects in vitro and in vivo which could be the result of mechanisms targeting cell metabolism. Our objective is to characterize the modifications of breast cancer cell metabolism after ∆2-Troglitazone (∆2T) exposure and to compare it with the effects of 2-deoxyglucose (2-DG), a well known inhibitor of glucose metabolism.Methods: The triple-negative breast cancer cell line MDA-MB231 cells were exposed to D2T and 2-DG. Cell numbers were assessed by crystal violet staining assay. Cell proliferation was determined by BrDU incorporation assay. Gene expression was analysed by RT-PCR. Protein expression was analyzed by immunoblotting and immunolocalisation.Results: 48h cell treatment with increasing concentrations of D2T (0-100µM) and 2-DG (0-10mM) inhibited cell proliferation in a dose-dependent manner. Nevertheless, cell viability was not as much affected suggesting that D2T and 2-DG mainly slowed down cell cycle. Concomitantly, both compounds induced endoplasmic reticulum stress. In contrast to 2-DG, the effect of D2T was not reversed by addition of an excess of glucose. At the metabolic level, NAD+/NADH ratio was increased after a 24h treatment with D2T or 2-DG. Under the same conditions, the mRNA levels of two key glycolysis enzymes, hexokinase and phosphofructokinase, were reduced.Conclusion: Our studies show that ∆2T and 2-DG induce changes in triple-negative breast cancer cell metabolism. The importance of the metabolic deregulation in the antitumoral effect of ∆2T has now to be demonstrated

Delta2-Troglitazone alters energetic metabolism in triple-negative breast cancer cells: a mechanism to sensitize cancer cells to chemotherapy?

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Delta-2-Troglitazone targets mitochondria in triple-negative breast cancer cells: a metabolic change contributing to sensitization of cancer cells to chemotherapy?

Présentation PosterNational audienceBackground: Resistance to conventional therapies for triple-negative mammary tumors are strong arguments for the search for new therapeutic agents. A strategy is to develop drugs targeting energetic metabolism to sensitize cancer cells to chemotherapy. Thiazolidinediones display antiproliferative effects which could be the result of mechanisms altering cell metabolism. Our objectives are to characterize the modifications of the triple-negative breast cancer cell line MDA-MB231 metabolism after Delta-2-Troglitazone (D2T) exposure and to define whether D2T could potentiate the action of chemotherapeutic agents.Methods: Cell numbers were assessed by crystal violet staining. NAD+ and NADH concentrations were determined by chemiluminescence. Lactate and glucose concentrations were measured with an YSI 2950 Biochemistry Analyzer. Mitochondrial activity was assessed by oxygraphy. Results: 48h cell treatment with D2T (75 µM) inhibited cell proliferation. At the metabolic level, NAD+/NADH ratio was increased after a 24h treatment, suggesting that glycolysis and/or mitochondrial respiration could be altered. Oxygen consumption was diminished after a 24h exposure to D2T, associated with a decreased mitochondrial efficiency and a mitochondrial decoupling. At the glycolytic level, lactate production and glucose consumption were increased in D2T-treated cells. Finally, D2T at a lower dose (15 µM) potentiated the effects of 2-DG (2-Deoxyglucose, a glycolytic inhibitor) and doxorubicin on cell viability. Conclusion: D2T induces metabolic changes in cancer cells MDA-MB231. D2T targets mitochondrial activity likely leading to the stimulation of glycolysis. Besides, a low dose of D2T potentiates the action of 2-DG and doxorubicin on cell viability. The impact of the D2T/doxorubicin combination on proliferation and apoptosis has to be characterized. Overall, the link between the metabolic alteration observed with D2T and its antiproliferative effect has to be demonstrated

Le « drug reprofiling » appliqué à la troglitazone : vers un nouveau traitement anticancéreux ?

National audienceMalgré les sommes toujours plus colossales investies dans la recherche et le développement par les entreprises pharmaceutiques, peu de nouvelles entités moléculaires sont effectivement mises sur le marché. Il est ainsi nécessaire de développer des approches originales pour la découverte de nouvelles molécules actives. Parmi celles-ci, le «drug reprofiling» est une démarche intéressante. Elle consiste à identifier et à développer de nouveaux usages pour des médicaments existants. Par exemple, les molécules de la famille des glitazones qui sont utilisées pour le traitement du diabète ont montré une activité antiproliférative. L’effet anticancéreux a été confirmé par des méta-analyses dans des cohortes de patients diabétiques traités par ces composés, mais aussi en bithérapie avec des inhibiteurs de tyrosine kinase. En suivant cette démarche, nous avons développé des analogues de la troglitazone qui avait montré une activité antiproliférative sur diverses lignées de cellules cancéreuses. Nous avons optimisé sa structure de façon à 1) augmenter son activité antiproliférative et 2) diminuer sa toxicité envers les cellules non cancéreuses et 3) augmenter sa stabilité métabolique. En effet, les molécules obtenues ont montré une activité de l’ordre du micromolaire sur diverses lignées cellulaires cancéreuses alors que des hépatocytes non cancéreux y sont complètement insensibles. Corrélativement, la demi-vie (t½) du composé leader est nettement supérieure à celle du composé parent après administration par voie iv à des souris

Protein N-glycosylation alteration and glycolysis inhibition both contribute to the antiproliferative action of 2-deoxyglucose in breast cancer cells

International audiencePurpose : Cancer cells often elicit a higher glycolytic rate than normal cells, supporting the development of glycolysis inhibitors as therapeutic agents. 2-Deoxyglucose (2-DG) is used in this context due to its ability to compete with glucose. However, many studies do not take into account that 2-DG inhibits not only glycolysis but also N-glycosylation. Since there are limited publications on 2-DG mechanism of action in breast cancer, we studied its effects in breast cancer cell lines to determine the part played by glycolysis inhibition and N-linked glycosylation interference.Methods and Results : 2-Deoxyglucose behaved as an anticancer agent with a similar efficiency on cell number decrease between the hormone-dependent MCF-7 and hormone-independent MDA-MB-231 breast cancer cells. It also interfered with the N-linked glycosylation process in both cell lines as illustrated by the migration profile of the lysosomal-associated membrane protein 2 and calumenin. These results are reinforced by the appearance of an abnormal Man7GlcNAc2 structure both on lipid-linked oligosaccharides and N-linked glycoproteins of 2-DG incubated MDA-MB-231 cells. Besides, 2-DG-induced a transient endoplasmic reticulum stress that was more sustained in MDA-MB-231 cells. Both changes were abrogated by mannose. 2-DG, even in the presence of mannose, decreased glycolysis in both cell lines. Mannose partially reversed the effects of 2-DG on cell numbers with N-linked glycosylation interference accounting for 37 and 47% of 2-DG anti-cancerous effects in MDA-MB-231 and MCF-7 cells, respectively.Conclusion : N-linked glycosylation interference and glycolysis disruption both contribute to the anticancer properties of 2-DG in breast cancer cells

Le repositionnement de la TGZ, une stratégie intéressante pour le traitement des tumeurs mammaires triple-négatives?

National audienceLe cancer du sein est un problème majeur de santé publique. En France, il représente la première cause de décès par cancer chez la femme. L'existence de tumeurs mammaires qui ne répondent pas aux traitements ou qui acquièrent une résistance, justifie le développement de nouveaux composés à action anticancéreuse. Une stratégie en pleine expansion est de "repositionner" d’anciennes molécules déjà utilisées cliniquement pour de nouveaux usages thérapeutiques. Notre équipe travaille depuis plusieurs années sur le repositionnement de la troglitazone (TGZ), un agoniste synthétique du récepteur PPARgamma initialement utilisé comme antidiabétique mais qui présentait aussi des effets anticancéreux décrits dès les années 90. Cet antidiabétique a dû être retiré du marché en raison de son hépato-toxicité. En tenant compte du mécanisme d’action de la TGZ, de sa métabolisation et des effets secondaires sur les hépatocytes, nous avons développé et breveté de nouveaux composés. Ces dérivés insaturés n’activent plus PPARgamma, ils ont une activité anticancéreuse accrue et sont moins toxiques pour les hépatocytes humains. Nos recherches actuelles sont dédiées à la compréhension du mécanisme d’action de ces dérivés. Nous nous focalisons sur l’atteinte du métabolisme énergétique d’une part et la réexpression de la claudine 1, protéine des jonctions cellulaires, d’autre part. Des études in vivo sont en cours. L'utilisation de ces composés seuls ou en association avec d'autres agents anticancéreux pourrait constituer une piste thérapeutique novatrice pour les tumeurs triple-négatives, en particulier les tumeurs « claudin 1 low » qui sont de mauvais pronostic