The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform

Michael Wink - One of the best experts on this subject based on the ideXlab platform.

  • telomere shortening in breast cancer cells mcf7 under treatment with low doses of the benzylisoquinoline alkaloid Chelidonine
    PLOS ONE, 2018
    Co-Authors: Sakineh Kazemi Noureini, Leili Fatemi, Michael Wink
    Abstract:

    Telomeres, the specialized dynamic structures at chromosome ends, regularly shrink with every replication. Thus, they function as an internal molecular clock counting down the number of cell divisions. However, most cancer cells escape this limitation by activating telomerase, which can maintain telomere length. Previous studies showed that the benzylisoquinoline alkaloid Chelidonine stimulates multiple modes of cell death and strongly down-regulates telomerase. It is still unknown if down-regulation of telomerase by Chelidonine boosts substantial telomere shortening. The breast cancer cell line MCF7 was sequentially treated with very low concentrations of Chelidonine over several cell passages. Telomere length and telomerase activity were measured by a monochrome multiplex quantitative PCR and a q-TRAP assay, respectively. Changes in population size and doubling time correlated well with telomerase inhibition and telomere shortening. MCF7 cell growth was arrested completely after three sequential treatments with 0.1 μM Chelidonine, each ending after 48 h, while telomere length was reduced to almost 10% of the untreated control. However, treatment with 0.01 μM Chelidonine did not have any apparent consequence. In addition to dose and time dependent telomerase inhibition, Chelidonine changed the splicing pattern of hTERT towards non-enzyme coding isoforms of the transcript. In conclusion, telomere length and telomere stability are strongly affected by Chelidonine in addition to microtubule formation.

  • Cell viability of MCF7 cells after 48 h treatment with different concentrations of Chelidonine was estimated using MTT test; mean values of four independent experiments ± SEM are shown.
    2018
    Co-Authors: Sakineh Kazemi Noureini, Leili Fatemi, Michael Wink
    Abstract:

    Cell viability of MCF7 cells after 48 h treatment with different concentrations of Chelidonine was estimated using MTT test; mean values of four independent experiments ± SEM are shown.

  • Telomere shortening in breast cancer cells (MCF7) under treatment with low doses of the benzylisoquinoline alkaloid Chelidonine - Fig 2
    2018
    Co-Authors: Sakineh Kazemi Noureini, Leili Fatemi, Michael Wink
    Abstract:

    A) Number of population doublings and B) doubling time after long-term treatment with Chelidonine (0.01; diamonds or 0.05 μM; squares) in comparison with untreated control MCF7 cells (triangles).

  • Alternative splice variants of hTERT from MCF-7 cells after 48 h treatment with 2 and 8 μM Chelidonine in parallel with that of untreated cells.
    2018
    Co-Authors: Sakineh Kazemi Noureini, Leili Fatemi, Michael Wink
    Abstract:

    PCR products were analysed by gel electrophoresis (3% agarose gels). The white arrows show the location of four splice variants in untreated cells. The upper band is the functional full-length hTERT (FL, 457 bp) which is followed by the three shorter non-enzyme coding variants. Lane 1: negative control, 2: treatment with 5 μM Chelidonine, 3: treatment with 2 μM Chelidonine, 4: untreated control and 5: 100 bp DNA marker from which 10, 10, 10, 5 and 5 μl was loaded respectively; as seen in Fig 4B the total transcription of hTERT was strongly repressed while the major isoform is minus beta. Five microliters of β2-microglobulin PCR products of the related samples have been loaded as control at bottom.

  • The Interference of Selected Cytotoxic Alkaloids with the Cytoskeleton: An Insight into Their Modes of Action
    MDPI AG, 2016
    Co-Authors: Xiaojuan Wang, Mine Tanaka, Sonja Krstin, Herbenya Silva Peixoto, Michael Wink
    Abstract:

    Alkaloids, the largest group among the nitrogen-containing secondary metabolites of plants, usually interact with several molecular targets. In this study, we provide evidence that six cytotoxic alkaloids (sanguinarine, chelerythrine, Chelidonine, noscapine, protopine, homoharringtonine), which are known to affect neuroreceptors, protein biosynthesis and nucleic acids, also interact with the cellular cytoskeleton, such as microtubules and actin filaments, as well. Sanguinarine, chelerythrine and Chelidonine depolymerized the microtubule network in living cancer cells (Hela cells and human osteosarcoma U2OS cells) and inhibited tubulin polymerization in vitro with IC50 values of 48.41 ± 3.73, 206.39 ± 4.20 and 34.51 ± 9.47 μM, respectively. However, sanguinarine and chelerythrine did not arrest the cell cycle while 2.5 μM Chelidonine arrested the cell cycle in the G2/M phase with 88.27% ± 0.99% of the cells in this phase. Noscapine and protopine apparently affected microtubule structures in living cells without affecting tubulin polymerization in vitro, which led to cell cycle arrest in the G2/M phase, promoting this cell population to 73.42% ± 8.31% and 54.35% ± 11.26% at a concentration of 80 μM and 250.9 μM, respectively. Homoharringtonine did not show any effects on microtubules and cell cycle, while the known microtubule-stabilizing agent paclitaxel was found to inhibit tubulin polymerization in the presence of MAPs in vitro with an IC50 value of 38.19 ± 3.33 μM. Concerning actin filaments, sanguinarine, chelerythrine and Chelidonine exhibited a certain effect on the cellular actin filament network by reducing the mass of actin filaments. The interactions of these cytotoxic alkaloids with microtubules and actin filaments present new insights into their molecular modes of action

Sakineh Kazemi Noureini - One of the best experts on this subject based on the ideXlab platform.

Andrea Bodnár - One of the best experts on this subject based on the ideXlab platform.

  • Chelidonine Interferes with IL-6R/STAT3 Signaling in Uveal Melanoma Cells
    Biophysical Journal, 2015
    Co-Authors: István Csomós, Eniko Nizsaloczki, Gabriella Nagy, László Mátyus, Andrea Bodnár
    Abstract:

    There is increasing evidence suggesting the importance of IL-6 in oncogenesis: it stimulates tumor cells proliferation and promotes cell survival through the inhibition of apoptosis. IL-6 acts on a receptor complex consisting of the cytokine-specific IL-6Rα chain and the signal-transducing gp130 subunit. Binding of IL-6 to IL-6Rα induces dimerization of gp130 which initiates multiple signaling cascades, including STAT3 activation.Chelidonine, the major alkaloid component of C. majus, provokes cell death in a variety of tumor cells, possibly through the antiapoptotic Bcl-2 protein. Expression of Bcl-2 is upregulated by STAT3 activation, which is thought to be responsible for IL-6-mediated survival of tumor cells.Herein we aimed to study the effect of Chelidonine on the viability of human uveal melanoma cells as wells as its interference with the IL-6R/STAT3 signaling pathway.Antiproliferative and cell death-inducing effects of Chelidonine were assessed by flow cytometry. The apoptotic potential of Chelidonine was followed by DNA fragmentation and PI exclusion/annexin V binding assays. Expression of STAT3, Bcl-2 and IL-6Rα and the efficiency of STAT3 activation was also studied by flow cytometry.Combined analysis of cell death experiments revealed Chelidonine-induced apoptosis of UM cells. Moreover, alkaloid treatment also resulted in necrotic cell death.Pretreatment of cells even with sublethal doses of Chelidonine led to the appearance of a subpopulation with abrogated STAT3 activation upon IL-6 stimulation and modified Bcl-2 expression levels. We detected cells with reduced expression of STAT3 and IL-6Rα; however, the amount of these cells was significantly lower than that of cells with abolished STAT3 signaling.According to our results Chelidonine exerts its effect via a STAT3-dependent mechanism. Our findings imply the possible use of Chelidonine in cancer therapy: it can either provoke cell death or weaken the antiapoptotic machinery of tumor cells fueled by IL-6.

  • apoptotic response of uveal melanoma cells upon treatment with Chelidonine sanguinarine and chelerythrine
    Cancer Letters, 2006
    Co-Authors: Adam Kemenybeke, Janos Aradi, Judit Damjanovich, Zoltan Beck, Andrea Facsko, Andras Berta, Andrea Bodnár
    Abstract:

    The benzophenanthridine alkaloids sanguinarine, chelerythrine and Chelidonine were reported previously to provoke cell death in a variety of tumor cells suggesting their potential application as anticancer agents. Here we tested their effects on a primary human uveal melanoma cell line, OCM-1. Flow cytometric analysis of annexin V binding/PI exclusion and DNA fragmentation disclosed that all these alkaloids could induce apoptosis in OCM-1 cells. Moreover, necrotic cell death was also observed upon alkaloid treatment. As it was also evidenced by light microscopic inspection of cellular morphology, Chelidonine primarily caused apoptosis, while sanguinarine and chelerythrine were effective via a so-termed bimodal cell death (apoptosis and primary necrosis). The relative efficiencies of the two modes depended on the applied dose. This study is the first implication for the possible use of these alkaloids in the therapy of uveal melanomas, for which no really efficient therapeutic regimen is available so far.

Annie Panzer - One of the best experts on this subject based on the ideXlab platform.

  • Influence of Chelidonine, an inhibitor of tubulin polymerisation on tyrosine kinase activity in normal, transformed and malignant cell lines
    Biomedical Research, 2004
    Co-Authors: Annie M. Joubert, Mona-liza Lottering, Annie Panzer
    Abstract:

    Chelidonine, a tertiary hexahydro-benzophenanthridine alkaloid is an inhibitor of tubulin polymerisation and has been revealed to arrest cells in G2/M. Since enhanced tyrosine kinase (TK) activity is linked to the transition from normal to the immortal malignant phenotype, the effect of 10 mM Chelidonine was evaluated on TK activity in normal, transformed and malignant cell lines after 2 hours of exposure. Chelidonine caused a stimulation of TK activity in two normal cell lines (human foreskin fibroblast (Hs27) and normal monkey kidney (NMK)). In contrast, an inhibition of TK activity was observed in transformed human embryonic kidney (Graham 293) and transformed African green monkey kidney (Vero), as well as in human cervical carcinoma (HeLa) and squamous oesophageal carcinoma (WHCO5) cells. Hs27 cells exposed to Chelidonine, revealed an increase in TK activity of 1.27-fold (P < 0.05). NMK cells showed a 1.15-fold increase in TK activity. A decrease in TK activity was observed in Graham 293 (0.91-fold) and Vero (0.45-fold) (P < 0.005) cells. In both HeLa and WHCO5 cells, the TK activity was reduced to 0.68-fold (P < 0.05) and 0.56-fold (P < 0.005) respectively. These data, including results from our previous studies, suggest a potential cross talk between the SAPK/JNK and TK signal transduction pathways and a possible differential effect of Chelidonine on the phosphorylation status of role players involved in determining the length of G2 arrest in normal versus transformed and malignant cells.

  • The effects of Chelidonine on tubulin polymerisation, cell cycle progression and selected signal transmission pathways.
    European journal of cell biology, 2001
    Co-Authors: Annie Panzer, Anna Margaretha Joubert, Pepita C. Bianchi, Ernest Hamel, J.c. Seegers
    Abstract:

    Chelidonine is a tertiary benzophenanthridine alkaloid known to cause mitotic arrest and to interact weakly with tubulin. Our interest in Chelidonine began when we found it to be a major contaminant of Ukrain, which is a compound reported to be selectively toxic to malignant cells. The effects of Chelidonine in two normal (monkey kidney and Hs27), two transformed (Vero and Graham 293) and two malignant (WHCO5 and HeLa) cell lines, were examined. Chelidonine proved to be a weak inhibitor of cell growth, but no evidence for selective cytotoxicity was found in this study. It was confirmed that Chelidonine inhibits tubulin polymerisation (IC50 = 24 microM), explaining its ability to disrupt microtubular structure in cells. A G2/M arrest results, which is characterised by abnormal metaphase morphology, increased levels of cyclin B1 and enhanced cdc2 kinase activity. Exposure of all cell lines examined to Chelidonine leads to activation of the stress-activated protein kinase/jun kinase pathway (SAPK/JNK).

  • Chemical analyses of Ukrain™, a semi-synthetic Chelidonium majus alkaloid derivative, fail to confirm its trimeric structure
    Cancer letters, 2000
    Co-Authors: Annie Panzer, Annie M. Joubert, J.n Eloff, C.f Albrecht, E Erasmus, J.c. Seegers
    Abstract:

    Ukrain has been described as a semi-synthetic Chelidonium majus alkaloid derivative, consisting of three Chelidonine alkaloids combined to triaziridide. We found the actions of Ukrain to be similar to the Chelidonium alkaloids it is prepared from, and therefore became concerned about its chemical integrity. Chemical analyses of Ukrain by thin layer chromatography, high-performance liquid chromatography and liquid chromatography-mass spectrometry was inconsistent with the proposed trimeric structure and demonstrated that at least some commercial preparations of Ukrain consist of a mixture of C. majus alkaloids (including Chelidonine).

J.c. Seegers - One of the best experts on this subject based on the ideXlab platform.

  • The effects of Chelidonine on tubulin polymerisation, cell cycle progression and selected signal transmission pathways.
    European journal of cell biology, 2001
    Co-Authors: Annie Panzer, Anna Margaretha Joubert, Pepita C. Bianchi, Ernest Hamel, J.c. Seegers
    Abstract:

    Chelidonine is a tertiary benzophenanthridine alkaloid known to cause mitotic arrest and to interact weakly with tubulin. Our interest in Chelidonine began when we found it to be a major contaminant of Ukrain, which is a compound reported to be selectively toxic to malignant cells. The effects of Chelidonine in two normal (monkey kidney and Hs27), two transformed (Vero and Graham 293) and two malignant (WHCO5 and HeLa) cell lines, were examined. Chelidonine proved to be a weak inhibitor of cell growth, but no evidence for selective cytotoxicity was found in this study. It was confirmed that Chelidonine inhibits tubulin polymerisation (IC50 = 24 microM), explaining its ability to disrupt microtubular structure in cells. A G2/M arrest results, which is characterised by abnormal metaphase morphology, increased levels of cyclin B1 and enhanced cdc2 kinase activity. Exposure of all cell lines examined to Chelidonine leads to activation of the stress-activated protein kinase/jun kinase pathway (SAPK/JNK).

  • Chemical analyses of Ukrain™, a semi-synthetic Chelidonium majus alkaloid derivative, fail to confirm its trimeric structure
    Cancer letters, 2000
    Co-Authors: Annie Panzer, Annie M. Joubert, J.n Eloff, C.f Albrecht, E Erasmus, J.c. Seegers
    Abstract:

    Ukrain has been described as a semi-synthetic Chelidonium majus alkaloid derivative, consisting of three Chelidonine alkaloids combined to triaziridide. We found the actions of Ukrain to be similar to the Chelidonium alkaloids it is prepared from, and therefore became concerned about its chemical integrity. Chemical analyses of Ukrain by thin layer chromatography, high-performance liquid chromatography and liquid chromatography-mass spectrometry was inconsistent with the proposed trimeric structure and demonstrated that at least some commercial preparations of Ukrain consist of a mixture of C. majus alkaloids (including Chelidonine).