1,721,028 research outputs found
Study of the mechanism of action of new molecules endowed with antitumoral activity
Full text linkThe microtubule system of eukaryotic cells is a critical element in a variety of fundamental cellular processes such as cell proliferation, mitotic spindle formation, maintenance of cell shape, regulation of motility, cell signaling, secretion, and intracellular transport. The important role of microtubules dynamic in mitosis progression and thus in cell proliferation, made them an attractive target for cancer therapy. Many chemically diverse compounds bind and affect tubulin-microtubule system, altering polymerization and dynamics during the particularly vulnerable mitotic stage of the cell cycle, causing alteration in the spindle organization with a delay or block at the metaphase-anaphase transition during mitosis.
In this study we evaluated the antiproliferative activity of seven series of novel tubulin polymerization inhibitors deriving from three classes of colchicine site binders: combretastatin-A4, chalcones and pyrroloquinolinones. Furthermore we investigated on the inhibitory effects on tubulin polimerization, cell cycle alteration, and apoptosis induction in in vitro and in vivo models and described a possible mechanism of action. The studied compounds, showed antiproliferative activity derived from a interference with microtubule assembly similar or higher than the reference compounds. As general mechanisms of action, the interaction of such compounds with tubulin, induces cell cycle arrest in the G2/M phase, with increased expression of cyclin B1 and phosphorylation of cdc25c, that trigger to apoptosis in a time- and concentration-dependent manner with activation of caspase-3 and cleavage of PARP and reduction of Bcl-2 prosurvival protein. Moreover, several compounds was effective against cancer cell lines, characterized by high expression of glycoprotein-P and multidrug resistance-associated protein, resistant to chemotherapy drugs such as vinblastine, doxorubucine and taxol. Prelimary experiment carried out in vivo models of tumor xenograft showed a significative reduction of tumor growth suggesting a potential clinical applications for these compounds.Nelle cellule eucariotiche i microtubuli costituiscono un elemento cruciale nella regolazione di molteplici processi cellulari, tra cui la proliferazione, la formazione del fuso mitotico, il mantenimento della forma cellulare, la regolazione della motilità, il signaling cellulare, i processi di secrezione e trasporto intracellulare. Il ruolo fondamentale di tale struttura citoscheletrica nella progressione mitotica e di conseguenza nella proliferazione cellulare rende i microtubuli un ottimo target per la terapia antitumorale. Molti composti aventi struttura chimica differente sono in grado di legare il sistema tubulina-microtubuli, alterandone la polimerizzazione e la dinamica, in particolare durante la fase mitotica del ciclo cellulare, destabilizzando l'organizzazione del fuso mitotico, ritardando o bloccando la transizione metafase-anafase.
In questo studio è stata valutata l'attività antiproliferativa di sette serie di nuovi inibitori della polimerizzazione della tubulina, derivati da 3 classi di composti che legano i microtubuli a livello del sito di legame della colchicina:
combretastatina-A4, calconi e pirrolochinolinoni. In particolare, è stato studiato in modelli in vitro e in vivo l'effetto di tali inibitori sulla polimerizzazione della tubulina, sul ciclo cellulare e sull'attivazione dell'apoptosi per la descrizione di un possibile meccanismo d'azione. I composti testati hanno mostrato attività antiproliferativa comparabile o superiore rispetto ai composti di riferimento.
Per quanto riguarda il meccanismo d'azione, in generale, l'interazione di tali composti con la tubulina induce un blocco del ciclo cellulare in fase G2/M con l'aumento dell'espressione della ciclina B1 e la fosforilazione di Cdc25c. Tale arresto della progressione mitotica porta all'attivazione del processo apoptotico in modo tempo- e concentrazione- dipendente con la attivazione di caspase-3, il taglio proteolitico di PARP e la riduzione delle proteine Bcl-2 antiapoptotiche.
Inoltre, alcuni composti hanno mostrato elevata efficacia nell'indurre citotossicità in cellule tumorali multidrug resistant, esprimenti la licoproteina-P e le pompe di efflusso MDR, resistenti a chemioterapici quali vinblastina, doxorubucina e tassolo. Esperimenti preliminari, svolti in modelli murini di xenotrapianto, hanno mostrato una significativa riduzione della crescita tumorale, suggerendo una possibile applicazione clinica per alcuni dei composti studiati
9-(4-Dimethylaminophenyl)benzo[b]quinolizinium: A Near-Infrared Fluorophore for the Multicolor Analysis of Proteins and Nucleic Acids in Living Cells
No full textSynthesis, DNA-binding and antiproliferative properties of diarylquinolizinium derivatives
Full text linkA series of ten 2,7- and 2,8-diarylquinolizinium derivatives was synthesized and their DNA-binding and cytotoxic properties were investigated. Except for one nitro-substituted derivative all tested diarylquinolizinium ions bind to DNA with sufficient affinity (2 × 104 M-1-2 × 105 M-1). It was shown with photometric, fluorimetric and polarimetric titrations as well as with flow-LD analysis that the ligands bind mainly by intercalation to duplex DNA, however, depending on the ligand-DNA ratio, groove binding and backbone association were also observed with some derivatives. The biological activity was further investigated with tests of cytotoxicity and antiproliferative properties towards non-tumor cells and selected cancer cells, along with cell cycle analysis and an annexin-V assay. Notably, substrates that carry donor-functionalities in the 4-position of the phenyl substituents revealed a strong, and in some cases selective, antiproliferative activity as quantified by the growth inhibition, GI50, at very low micromolar and even submicromolar level both in leukemia and solid tumors
Surviving the hunger games: Metabolic reprogramming in medulloblastoma
Full text link: Medulloblastoma is a highly malignant pediatric brain tumor characterized by its aggressive nature and limited treatment options. Metabolic changes have recently emerged as key factors in the development, progression, and response to therapy in various types of cancer. Cancer cells exhibit remarkable adaptability by modulating glucose, lipids, amino acids, and nucleotide metabolism to survive in nutrient- and oxygen-deprived environments. Although medulloblastoma has been extensively studied from a genomic perspective, leading to the identification of four subgroups and their respective subcategories, the investigation of its metabolic phenotype has remained relatively understudied. This review focus on the available literature, aiming to summarize the current knowledge about the main metabolic pathways that are deregulated in medulloblastoma tumors, while emphasizing the controversial aspects and the progress that is yet to be made. Furthermore, we underscored the insights gained so far regarding the impact of metabolism on the development of drug resistance in medulloblastoma and the therapeutic strategies employed to target specific metabolic pathways
Discovery of MG-2603 with in vitro potent antiproliferative activity by interfering with kinases and tubulin polymerisation
No full textNovel 3-Substituted 7-Phenylpyrrolo[3,2-f]quinolin-9(6H)-ones as Single Entities with Multitarget Antiproliferative Activity
No full textA series of chemically modified 7-phenylpyrrolo[3,2-f]quinolinones was synthesized and evaluated as anticancer agents. Among them, the most cytotoxic (subnanomolar GI50 values) amidic derivative 5f was shown to act as an inhibitor of tubulin polymerization (IC50, 0.99 μM) by binding to the colchicine site with high affinity. Moreover, 5f induced cell cycle arrest in the G2/M phase of the cell cycle in a concentration dependent manner, followed by caspase-dependent apoptotic cell death. Compound 5f also showed lower toxicity in nontumoral cells, suggesting selectivity toward cancer cells. Additional experiments revealed that 5f inhibited the enzymatic activity of multiple kinases, including AURKA, FLT3, GSK3A, MAP3K, MEK, RSK2, RSK4, PLK4, ULK1, and JAK1. Computational studies showed that 5f can be properly accommodated in the colchicine binding site of tubulin as well as in the ATP binding clefts of all examined kinases. Our data indicate that the excellent antiproliferative profile of 5f may be derived from its interactions with multiple cellular targets
A novel copper(I) induces ER stress-mediated apoptosis in leukemia cell lines
No full textRecently, a novel phosphine copper(I) complex [Cu(thp)4][PF6] (CP), was identified as an efficient, in vitro antitumoral agents. It has also been demonstrated that it induces in colon cancer cells a programmed nonapototic cell death called paraptosis or type III cell death. In this study we evaluated CP antiproliferative activity on a panel of leukemia cell lines and it significantly inhibited cancer cells growth at micro and submicromolar concentration, especially against SEM and RS4;11 cell lines. Flow cytometric analysis demonstrated that CP did not affected cell cycle in RS4;11 and SEM cell line but we observed a concentration-dependent increase of the cell population with a hypodiploid DNA content peak (subG1),
suggesting that CP may induce apoptosis. To better characterize the mode of cell death induced by CP, a biparametric cytofluorimetric analysis was performed using propidium iodide (PI), which stains DNA and is permeable only to dead cells, and fluorescent immunolabeling of the protein annexin-V, which binds to PS in a highly selective manner. We found a concentration-dependent increase in annexin-V positive cells in well agreement with the appearance of hypodipolid peak. Western blot analysis demonstrated that the
activation of the apical caspase-9 and the two effector caspase-3 and 7 occur after treatment with CP, while caspase-8 was not affected by the treatment. Interestingly we did not observed mitochondrial depolarization or cytochrome c release into the cytoplasm, suggesting that mitochondria was not involved in the process of cell death. Previous observations indicated that CP may induces functional suppression of the ubiquitin–proteasome pathway thus triggering endoplasmic reticulum stress in solid tumor cells. We
also evaluated if CP exerts ER stress in leukemia cell lines. Western blot analysis showed a remarkable increase of GRP78 in RS4;11 and SEM, a well known marker of ER stress. Moreover the protein synthesis inhibitor cicloheximide significantly protected the cells from CP-induced cell death suggesting that protein synthesis machinery is involved in the mechanism of action. To evaluate if CP directly inhibits the proteasome, semipurified proteasome from cell extracts were incubated with increasing concentrations of
CP and the chymotrypsin-like activity was measured. The results showed a decreased activity in a concentration-dependent way, with an IC50 of approximately 12 μM. It is well known that copper represent an excellent catalyst of redox cycle and therefore it can stimulate ROS production. Interestingly the CP-induced cell death was significantly reduced in presence of ROS scavenger such as tocopherol, nacetyl cysteine (NAC) and butylated hydroxyanisole (BHA) suggesting that also ROS may contribute to the process of cell death. Further experiments are in progress to elucidate the mechanism of action of this copper complex and the results will be discussed
Discovery of a novel class of anti-proliferative pyrrolo[3,2-f]quinolin-9-ones characterized by interfering with both PI3K-Akt-mTOR signalling and microtubule assembling
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Selective ratiometric detection of H2O2in water and in living cells with boronobenzo[b]quinolizinium derivatives
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