Transient TNF regulates the self-renewing capacity of stem-like label-retaining cells in sphere and skin equivalent models of melanoma.

International audience: BackgroundIt is well established that inflammation promotes cancer, including melanoma, although the exact mechanisms involved are less known. In this study, we tested the hypothesis that inflammatory factors affect the cancer stem cell (CSC) compartment responsible for tumor development and relapse.ResultsUsing an inducible histone 2B-GFP fusion protein as a tracer of cell divisional history, we determined that tumor necrosis factor (TNF), which is a classical pro-inflammatory cytokine, enlarged the CSC pool of GFP-positive label-retaining cells (LRCs) in tumor-like melanospheres. Although these cells acquired melanoma stem cell markers, including ABCB5 and CD271, and self-renewal ability, they lost their capacity to differentiate, as evidenced by the diminished MelanA expression in melanosphere cells and the loss of pigmentation in a skin equivalent model of human melanoma. The undifferentiated cell phenotype could be reversed by LY294002, which is an inhibitor of the PI3K/AKT signaling pathway, and this reversal was accompanied by a significant reduction in CSC phenotypic markers and functional properties. Importantly, the changes induced by a transient exposure to TNF were long-lasting and observed for many generations after TNF withdrawal.ConclusionsWe conclude that pro-inflammatory TNF targets the quiescent/slow-cycling melanoma SC compartment and promotes PI3K/AKT-driven expansion of melanoma SCs most likely by preventing their asymmetrical self-renewal. This TNF effect is maintained and transferred to descendants of LRC CSCs and is manifested in the absence of TNF, suggesting that a transient exposure to inflammatory factors imprints long-lasting molecular and/or cellular changes with functional consequences long after inflammatory signal suppression. Clinically, these results may translate into an inflammation-triggered accumulation of quiescent/slow-cycling CSCs and a post-inflammatory onset of an aggressive tumor

Pharmacologie et métabolisme de la fisétine, un flavonoïde à visée antiangiogénique tumorale. Optimisation de l'effet antitumoral de la fisétine chez la souris par association avec le cyclophosphamide et encapsulation liposomale en vue d'améliorer sa biodisponibilité

Viser la vascularisation tumorale peut être une approche thérapeutique intéressante. Parmi 24 flavonoïdes testés, la fisétine s est avérée la plus active sur la morphologie des cellules endothéliales avec une augmentation de la stabilité microtubulaire. Nous avons observé une diminution de la croissance tumorale (Lewis lung Carcinoma) chez des souris traitées à la fisétine, ainsi qu un effet antiangiogénique. Une association avec une faible dose de cyclophosphamide a conduit à une inhibition de la croissance tumorale de 92 %. Nous avons identifié un nouveau métabolite de la fisétine, le géraldol qui s est avéré actif in vitro sur les cellules tumorales. Une formulation liposomale a été mise au point. La biodistribution de la fisétine liposomale a montré une augmentation des concentrations sanguines de fisétine à comparer à la forme libre. Nos résultats pourraient contribuer au développement de médicaments anticancéreux antiangiogéniques de la famille des flavonoïdesTumor vasculature has become an attractive target forcancer therapy. Among 24 flavonoids, we show that fisetin, the most active compound of our series, can induce a rapid morphological modification of endothelial cells which is correlated with an increase in microtubule stability. Fisetin can significantly slow the Lewis lung tumor growth. When combined with low doses of cyclophosphamide, fisetin lead to a synergistic antitumoral action (92%) through an antiangiogenic mechanism of action.We have also identified a new metabolite of fisetin, geraldol which displayed cytotoxic activity against tumor cells in vitro. A liposomal preparation was developed. Blood concentrations of liposomal fisetin were increased compared to concentration of the free fisetin formulation. Collectively, our results have allowed the identification of new antiangiogenic antitumor agents in the flavonoid familyPARIS-BIUP (751062107) / SudocSudocFranceF

: Flavonoid-induced microtubule stabilization

International audienceFlavonoids are common components of the human diet and appear to be of interest in cancer prevention or therapy, but their structure-activity relationships (SAR) remain poorly defined. In this study, were compared 24 flavonoids for their cytotoxicity on cancer cells (B16 and Lewis lung) and their morphological effect on endothelial cells (EC) that could predict antiangiogenic activity. Ten flavonoids presented inhibitory concentrations for 50% of cancer cells (IC50, 48 h) below 50 microM: rhamnetin, 3',4'-dihydroxyflavone, luteolin, 3-hydroxyflavone, acacetin, apigenin, quercetin, baicalein, fisetin, and galangin. Important SAR for cytotoxicity included the C2-C3 double bond and 3',4'-dihydroxylation. Concerning the morphological effects on EC, only fisetin, quercetin, kaempferol, apigenin, and morin could induce the formation of cell extensions and filopodias at noncytotoxic concentrations. The SAR for morphologic activity differed from cytotoxicity and involved hydroxylation at C-7 and C-4'. Fisetin, the most active agent, presented cell morphology that was distinct compared to colchicine, combretastatin A-4, docetaxel, and cytochalasin D. Resistance to cold depolymerization and a 2.4-fold increase in acetylated alpha-tubulin demonstrated that fisetin was a microtubule stabilizer. In conclusion, this study disclosed several SAR that could guide the choice or the rational synthesis of improved flavonoids for cancer prevention or therapy

Improved antiangiogenic and antitumour activity of the combination of the natural flavonoid fisetin and cyclophosphamide in Lewis lung carcinoma-bearing mice.

International audiencePURPOSE: The natural flavonoid fisetin was recently identified as a lead compound that stabilizes endothelial cell microtubules. In this study, we investigated the antiproliferative and antiangiogenic properties of fisetin in vitro and in vivo. METHODS: Fisetin cytotoxicity was evaluated using Lewis lung carcinoma cells (LLC), endothelial cells and NIH 3T3 cells. Endothelial cell (EC) migration and capillary-like structure formation were evaluated using EAhy 926 cells. In vivo tumour growth inhibition studies were performed using LLC-bearing mice treated with fisetin and/or cyclophosphamide (CPA). RESULTS: The fisetin IC(50) was 59 μM for LLC and 77 μM for EC cells, compared to 210 μM for normal NIH 3T3 cells (24 h). Fisetin inhibited EC migration and capillary-like structure formation at non-cytotoxic concentrations (22-44 μM). In mice, fisetin inhibited angiogenesis assessed using the Matrigel plug assay. In LLC-bearing mice, fisetin produced a 67% tumour growth inhibition (223 mg/kg, intraperitoneal), similar to the 66% produced by low-dose CPA (30 mg/kg, subcutaneous). When fisetin and CPA were combined, however, a marked improvement in antitumour activity was observed (92% tumour growth inhibition), with low systemic toxicity. Tumour histology showed decreased microvessel density with either fisetin or CPA alone, and a dramatic decrease after the fisetin/CPA combination. CONCLUSIONS: We have shown that fisetin not only displays in vitro and in vivo antiangiogenic properties, but also can markedly improve the in vivo antitumour effect of CPA. We propose that this drug combination associating a non-toxic dietary flavonoid with a cytotoxic agent could advantageously be used in the treatment of solid tumours

La détection des évènements rares

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La détection des évènements rares

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LAM fatale ?: La signalisation calcique à la rescousse !

International audienceLa leucémie aiguë myéloïde (LAM) est une hémopathie maligne caractérisée par des aberrations génétiques de certains précurseurs hématopoïétiques de la lignée myéloïde qui entraînent un défaut de maturation et/ou de fonctionnement. Malgré une chimiothérapie intensive entraînant une rémission complète chez 50 à 80 % des patients, la rechute survient dans la majorité des cas. Bien que la signalisation calcique soit bien décrite dans les cancers solides, l’étude de cibles pertinentes dépendant du calcium a retenu peu d’attention dans la LAM jusqu’à aujourd’hui. L’objectif de cette revue est d’offrir une piste de réflexion sur l’identification de canaux calciques spécifiques et de voies de signalisation associées impliquées dans la LAM, et ainsi de promouvoir la recherche de nouvelles approches thérapeutiques efficaces ciblant spécifiquement ces voies

Aggressiveness potential of spontaneous canine mucosal melanoma can dictate distinct cancer stem cell compartment behaviors in regard to their initial size and expansion abilities

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Put in a “Ca2+ll” to Acute Myeloid Leukemia

International audienceAcute myeloid leukemia (AML) is a clonal disorder characterized by genetic aberrations in myeloid primitive cells (blasts) which lead to their defective maturation/function and their proliferation in the bone marrow (BM) and blood of affected individuals. Current intensive chemotherapy protocols result in complete remission in 50% to 80% of AML patients depending on their age and the AML type involved. While alterations in calcium signaling have been extensively studied in solid tumors, little is known about the role of calcium in most hematologic malignancies, including AML. Our purpose with this review is to raise awareness about this issue and to present (i) the role of calcium signaling in AML cell proliferation and differentiation and in the quiescence of hematopoietic stem cells; (ii) the interplay between mitochondria, metabolism, and oxidative stress; (iii) the effect of the BM microenvironment on AML cell fate; and finally (iv) the mechanism by which chemotherapeutic treatments modify calcium homeostasis in AML cells

Fisetin disposition and metabolism in mice: Identification of geraldol as an active metabolite.: Fisetin disposition and metabolism in mice

International audienceAlthough the natural flavonoid fisetin (3,3',4',7-tetrahydroxyflavone) has been recently identified as an anticancer agent with antiangiogenic properties in mice, its in vivo pharmacokinetics and metabolism are presently not characterized. Our purpose was to determine the pharmacokinetics and metabolism of fisetin in mice and determine the biological activity of a detected fisetin metabolite. After fisetin administration of an efficacious dose of 223 mg/kg i.p. in mice, the maximum fisetin concentration reached 2.5 μg/ml at 15 min and the plasma concentration declined biphasically with a rapid half-life of 0.09 h and a terminal half-life of 3.1h. Three metabolites were detected, one of which was a glucuronide of fisetin (M1), whereas another glucuronide (M2) was a glucuronide of a previously unknown fisetin metabolite (M3). HPLC-MS/MS analysis indicated that M3 was a methoxylated metabolite of fisetin (MW=300 Da). The UV spectrum of M3 was identical to that of fisetin and standard 3,4',7-trihydroxy-3'-methoxyflavone (geraldol). In addition, because M3 co-eluted with standard geraldol in 4 different chromatographic ternary gradient conditions, M3 was therefore assigned to geraldol. Of interest, this metabolite was shown to achieve higher concentrations than fisetin in Lewis lung tumors. We also compared the cytotoxic and antiangiogenic activities of fisetin and geraldol in vitro and it was found that the latter was more cytotoxic than the parent compound toward tumor cells, and that it could also inhibit endothelial cells migration and proliferation. In conclusion, these results suggest that fisetin metabolism plays an important role in its in vivo anticancer activities