Characterization of in vitro and in vivo anti-cancer properties of narciclasine in experimental models of murin and human melanoma

Le mauvais pronostic associé aux mélanomes est dû aux taux de réponses très faibles de ces cancers à la radiothérapie et à la chimiothérapie, cette résistance provenant essentiellement de la résistance des mélanomes aux stimuli pro-apoptotiques qui représentent la majorité de l’arsenal anticancéreux actuel.Les plantes de la famille des Amaryllidaceae ont été utilisées dans la médecine traditionnelle à travers le monde notamment pour le traitement des tumeurs. Il s’est avéré que les composés responsables de l’activité anticancéreuse de ces traitements traditionnels étaient des alcaloïdes, dont les isocarbostyriles. Nous avons voulu caractériser les propriétés anticancéreuses de la narciclasine, un isocarbostyrile, in vitro et in vivo, et étudier son mécanisme d’action antitumoral dans des cellules de mélanome.Nous avons tout d’abord analysé l’activité inhibitrice de croissance in vitro de ces composés et nous avons observé que l’activité de ces produits était indépendante du caractère résistant ou non des lignées cancéreuses aux stimuli pro-apoptotiques. De plus, à l’exception de la pseudolycorine, ces composés ont une activité cytostatique au niveau de la croissance des cellules cancéreuses. Nous avons ensuite identifié le facteur d’élongation eEF1A, une GTPase, comme étant une cible potentielle de la narciclasine. De nombreux effets biologiques exercés par la narciclasine (inhibition de la synthèse protéique, désorganisation du cytosquelette d’actine, etc…) peuvent s’expliquer grâce à cette cible. Des travaux antérieurs à ma thèse mais auxquels j’ai participé, suggéraient déjà l’implication d’autres GTPases appartenant à la famille des Rho GTPases comme pouvant être également des cibles de la narciclasine. Nous avons également identifié au cours de notre travail de thèse d’autres GTPases, telle que Rac1, comme étant des cibles de la narciclasine. Nous avons toutefois observé que certaines GTPases telles que Ran ne semblaient pas être des cibles de la narciclasine lorsque celle-ci exerce ses effets antitumoraux. Ainsi, si de nombreuses GTPases semblent être des cibles privilégiées de l’action antitumorale de la narciclasine, toutes les GTPases ne le sont pas. Nous avons observé en fait que la narciclasine n’entre pas en compétition avec le GDP / GTP au sein de la poche GTP du facteur d’élongation eEF1A. Des études d’activité in vivo réalisées par notre groupe, soit antérieures à mon travail de thèse (gliomes, cancer du poumon NSCLC), soit au cours de ma thèse (mélanomes), ont montré que la narciclasine à des doses non toxiques (administrations chroniques de 1 mg/kg par voie orale ou par voie intraveineuse) apporte un bénéfice thérapeutique dans différents types de modèles de cancers (gliomes, mélanomes, cancers NSCLC) à conditions que les cellules tumorales soient greffées de manière orthotopique au sein du cerveau de souris immunodéficientes. Ces mêmes cancers s’avèrent insensibles à ces doses non toxiques de narciclasine lorsque les cellules sont greffées en dehors du cerveau chez la souris immunodéficiente. L’ensemble de nos résultats suggèrent que la narciclasine pourrait devenir un nouvel outil dans le combat contre les cancers cérébraux primaires et secondaires, les métastases cérébrales constituants un problème d’importance pour des cancers tels que les mélanomes, les cancers du poumon, les cancers du sein, les cancers rénaux et les cancers colorectaux. Les cancers primaires du cerveau représentent environ 5% de l’ensemble des cancers solides de l’adulte et jusqu’à 20-30% chez l’enfant. Les métastases cérébrales, dont principalement les métastases cérébrales de mélanomes, représentent également environ 5% de l’ensemble des cancers solides de l’adulte.Doctorat en Sciences biomédicales et pharmaceutiquesinfo:eu-repo/semantics/nonPublishe

In Vitro Growth Inhibitory Effects of Cytochalasins and Derivatives in Cancer Cells.

The IN VITRO anticancer activity of eight natural cytochalasins and three hemisynthetic derivatives of cytochalasin B on six cancer cell lines was evaluated. The IC (50) IN VITRO growth inhibitory concentrations, as determined by an MTT colorimetric assay, ranged between 3 and 90 µM and did not relate to the intrinsic sensitivity of the cancer cell lines to proapoptotic stimuli. Structure activity relationship (SAR) analyses revealed that the presence of an unmodified hydroxyl group at C-7 of the perhydroisoinsolyl-1-one residue as well as the functionalities and the conformational freedom of the macrocycle are all important features for cytochalasin-mediated anticancer activities IN VITRO. Computer-assisted phase-contrast microscopy revealed two groups of cytochalasins, i.e. cytotoxic versus cytostatic ones. Our data open new possibilities for tuning cytochalasin targets and developing nontoxic, cytostatic cytochalasins to combat cancers associated with poor prognoses, such as those that display intrinsic resistance to proapoptotic stimuli.JOURNAL ARTICLESCOPUS: ar.jinfo:eu-repo/semantics/publishe

New ursane-type triterpenes from the root bark of Calotropis procera.

As a part of our continuing interest in identifying anticancer drug leads from natural sources, we have investigated the in vitro growth inhibitory effects of the hexane fraction of the root bark of Calotropis procera (Ait) R. Br. (Asclepiadaceae). This study reports the isolation and structure elucidation of four new ursane-type triterpenes named calotroprocerol A (1), calotroproceryl acetate A (2), calotroprocerone A (3) and calotroproceryl acetate B (4) in addition to five known compounds including pseudo-taraxasterol acetate (5), taraxasterol (6), calotropursenyl acetate B (7), stigmasterol (8) and (E)-octadec-7-enoic acid (9). Their structures were established on the basis of 1D and 2D NMR studies ( 1H- 1H COSY, HSQC, and HMBC) and HRMS spectral data. The in vitro growth inhibitory activity of the isolated compounds was evaluated against three human cancer cell lines including the A549 non-small cell lung cancer (NSCLC), the U373 glioblastoma (GBM) and the PC-3 prostate cancer cell lines. © 2012 Phytochemical Society of Europe.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

JLK1486, a Bis 8-Hydroxyquinoline-Substituted Benzylamine, Displays Cytostatic Effects in Experimental Gliomas through MyT1 and STAT1 Activation and, to a Lesser Extent, PPARγ Activation12

Gliomas account for 5% to 7% of all solid cancers in adults and up to 30% of solid cancers in children; glioblastomas are the most malignant type of glioma and often have dismal prognoses. The alkylating agent temozolomide provides the greatest chemotherapeutic benefits currently available; however, glioblastoma patients cannot be cured. Novel drugs that efficiently combat glioblastomas are therefore of great interest. We report here that JLK1486, an 8-hydroxyquinoline-substituted benzylamine, could represent a novel chemical scaffold to reach this goal. Indeed, JLK1486 mediated anticancer activity in vivo (through intravenous as well as oral routes of administrations) in an orthotopic xenograft model and displayed efficiency similar to that of temozolomide. The therapeutic benefits of JLK1486 seem to relate to its ability to activate various transcription factors (including Myt1, STAT1, and peroxisome proliferator-activated receptor γ) in glioma cells. These transcription factors are implicated in the control of glioma cell proliferation, and the resultant global effect of their activation by JLK1486 was cytostatic, not cytotoxic. Thus, the current study opens the door for the development of novel compounds to combat glioblastoma using 8-hydroxyquinoline benzylamine analogs

Bis-8-hydroxy-quinoline and Bis-8-hydroxy-quinaldine N-substituted amines: a single methyl group structural difference between the two heterocycles, wich modulates the antiproliferative effects

FLWINinfo:eu-repo/semantics/publishe

Amaryllidaceae alkaloids belonging to different structural subgroups display activity against apoptosis-resistant cancer cells.

Fifteen Amaryllidaceae alkaloids (1-15) were evaluated for their antiproliferative activities against six distinct cancer cell lines. Several of these natural products were found to have low micromolar antiproliferative potencies. The log P values of these compounds did not influence their observed activity. When active, the compounds displayed cytostatic, not cytotoxic activity, with the exception of pseudolycorine (3), which exhibited cytotoxic profiles. The active compounds showed similar efficacies toward cancer cells irrespective of whether the cell lines were responsive or resistant to proapoptotic stimuli. Altogether, the data from the present study revealed that lycorine (1), amarbellisine (6), haemanthamine (14), and haemanthidine (15) are potentially useful chemical scaffolds to generate further compounds to combat cancers associated with poor prognoses, especially those naturally resistant to apoptosis, such as glioblastoma, melanoma, non-small-cell lung, and metastatic cancers.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Narciclasine, a plant growth modulator, activates Rho and stress fibers in glioblastoma cells.

Cell motility and resistance to apoptosis characterize glioblastoma multiforme growth and malignancy. Narciclasine, a plant growth modulator, could represent a powerful new weapon targeting the Achilles' heel of glioblastoma multiforme and may offer the potential to better combat these devastating malignancies. The in vitro effects of narciclasine on cell proliferation, morphology, actin cytoskeleton organization, and the Rho/Rho kinase/LIM kinase/cofilin pathway and its antitumor activity in vivo have been determined in models of human glioblastoma multiforme. Narciclasine impairs glioblastoma multiforme growth by markedly decreasing mitotic rates without inducing apoptosis. The compound also modulates the Rho/Rho kinase/LIM kinase/cofilin signaling pathway, greatly increasing GTPase RhoA activity as well as inducing actin stress fiber formation in a RhoA-dependent manner. Lastly, the treatment of human glioblastoma multiforme orthotopic xenograft- bearing mice with nontoxic doses of narciclasine significantly increased their survival. Narciclasine antitumor effects were of the same magnitude as those of temozolomide, the drug associated with the highest therapeutic benefits in treating glioblastoma multiforme patients. Our results show for the first time that narciclasine, a plant growth modulator, activates Rho and stress fibers in glioblastoma multiforme cells and significantly increases the survival of human glioblastoma multiforme preclinical models. This statement is made despite the recognition that to date, irrespective of treatment, no single glioblastoma multiforme patient has been cured.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Targeting of eEF1A With Amaryllidaceae Isocarbostyrils as a Strategy to Combat Melanomas

Melanomas display poor response rates to adjuvant therapies because of their intrinsic resistance to proapoptotic stimuli. This study indicates that such resistance can be overcome, at least partly, through the targeting of eEF1A elongation factor with narciclasine, an Amaryllidaceae isocarbostyril controlling plant growth. Narciclasine displays IC50 growth inhibitory values between 30–100 nM in melanoma cell lines, irrespective of their levels of resistance to proapoptotic stimuli. Normal noncancerous cell lines are much less affected. At nontoxic doses, narciclasine also significantly improves (P=0.004) the survival of mice bearing metastatic apoptosis-resistant melanoma xenografts in their brain. The eEF1A targeting with narciclasine (50 nM) leads to 1) marked actin cytoskeleton disorganization, resulting in cytokinesis impairment, and 2) protein synthesis impairment (elongation and initiation steps), whereas apoptosis is induced at higher doses only (≥200 nM). In addition to molecular docking validation and identification of potential binding sites, we biochemically confirmed that narciclasine directly binds to human recombinant and yeast-purified eEF1A in a nanomolar range, but not to actin or elongation factor 2, and that 5 nM narciclasine is sufficient to impair eEF1A-related actin bundling activity. eEF1A is thus a potential target to combat melanomas regardless of their apoptosis-sensitivity, and this finding reconciles the pleiotropic cytostatic of narciclasine

In vitro anticancer activity, toxicity and structure-activity relationships of phyllostictine A, a natural oxazatricycloalkenone produced by the fungus Phyllosticta cirsii

The in vitro anticancer activity and toxicity of phyllostictine A, a novel oxazatricycloalkenone recently isolated from a plant-pathogenic fungus (Phyllosticta cirsii) was characterized in six normal and five cancer cell lines. Phyllostictine A displays in vitro growth-inhibitory activity both in normal and cancer cells without actual bioselectivity, while proliferating cells appear significantly more sensitive to phyllostictine A than non-proliferating ones. The main mechanism of action by which phyllostictine displays cytotoxic effects in cancer cells does not seem to relate to a direct activation of apoptosis. In the same manner, phyllostictine A seems not to bind or bond with DNA as part of its mechanism of action. In contrast, phyllostictine A strongly reacts with GSH, which is a bionucleophile. The experimental data from the present study are in favor of a bonding process between GSH and phyllostictine A to form a complex though Michael attack at C=C bond at the acrylamide-like system. Considering the data obtained, two new hemisynthesized phyllostictine A derivatives together with three other natural phyllostictines (B, C and D) were also tested in vitro in five cancer cell lines. Compared to phyllostictine A, the two derivatives displayed a higher, phyllostictines B and D a lower, and phyllostictine C an almost equal, growth-inhibitory activity, respectively. These results led us to propose preliminary conclusions in terms of the structure-activity relationship (SAR) analyses for the anticancer activity of phyllostictine A and its related compounds, at least in vitro.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe