The Experts below are selected from a list of 769593 Experts worldwide ranked by ideXlab platform
Claudio Stefanelli - One of the best experts on this subject based on the ideXlab platform.
-
control of survival of proliferating L1210 Cells by soluble guanylate cyclase and p44 42 mitogen activated protein kinase modulators
Biochemical Pharmacology, 2001Co-Authors: Flavio Flamigni, A Facchini, Benedetta Tantini, Ivana Stanic, Francesca Bonavita, Claudio StefanelliAbstract:Abstract Intracellular signaling pathways involved in the survival of proliferating L1210 leukemia Cells were investigated by using specific modulators. Among the various inhibitors tested, only 1H-[1,2,4]oxadiazole [4,3-a]quinoxalin-1-one (ODQ), a soluble guanylate cyclase (sGC) inhibitor, was found to induce a marked increase in caspase activity, which was associated with a loss of cell viability and a reduction in cGMP content. ODQ also provoked the processing of caspases-3 and -9, release of cytochrome c and, as early events, reduction of Bcl-2 content and dephosphorylation of Bad at Ser 112. Furthermore, YC-1, an sGC activator, and 8-Br-cGMP, a cell-permeant analogue of cGMP, exerted some protection against various apoptotic stimuli, such as serum deprivation or spermine accumulation. Although PD98059 (2′-amino-3′-methoxyflavone), an inhibitor of the p44/42 mitogen-activated protein kinase (MAPK) pathway, did not increase basal caspase activity, and ODQ did not affect p44/42 MAPK phosphorylation significantly, phorbol myristate acetate stimulated p44/42 MAPK and reduced caspase activation induced by ODQ, serum deprivation, and spermine in a p44/42-dependent manner. SB203580 (4-(4-fluorophenyl)-2-(4-methylsulfonylphenyl)-5-(4-pyridyl)1H-imidazole), a p38 MAPK inhibitor, also partially protected against ODQ-induced apoptosis by increasing p44/42 MAPK phosphorylation. In conclusion, these results suggest that sGC may be relevant both for survival of L1210 Cells under basal growing conditions and for protection against various apoptotic stimuli. p44/42 MAPK activation may also confer some protection from apoptosis, but apparently through a pathway largely independent of cGMP.
-
p44 42 mitogen activated protein kinase is involved in the expression of ornithine decarboxylase in leukaemia L1210 Cells
Biochemical Journal, 1999Co-Authors: Flavio Flamigni, A Facchini, Cristina Capanni, Claudio Stefanelli, Benedetta Tantini, C M CaldareraAbstract:The involvement of p44/42 mitogen-activated protein kinase (MAPK) in the induction of ornithine decarboxylase (ODC) was investigated by using PD98059, a specific MAPK-kinase (MEK1/2) inhibitor, and other signal-transduction inhibitors. In d,l-alpha-difluoromethylornithine (DFMO)-resistant L1210 Cells stimulated to grow from quiescence, treatment with PD98059 inhibited p44/42 MAPK phosphorylation and the induction of ODC activity and protein. A marked reduction of the accumulation of mature ODC mRNA and its intron-containing precursor was observed, whereas ODC turnover was hardly affected. PD98059 also reduced the content of antizyme, but not that of antizyme mRNA. U0126, a novel and more potent inhibitor of MEK1/2, provoked a dose-dependent inhibition of ODC induction at lower concentrations with respect to PD98059. Other effective inhibitors of ODC induction proved to be genistein, manumycin A, herbimycin A, LY294002, wortmannin and KT5823, suggesting the involvement of other key proteins of signal-transduction pathways, i.e. Ras, Src, phosphatidylinositol 3-kinase and cGMP-dependent protein kinase, which may have a positive impact on MAPK. Cells kept in a DFMO-free medium, and thus containing high levels of putrescine and spermidine, showed enhanced MAPK phosphorylation and lower sensitivity to PD98059, compared with Cells maintained in the presence of DFMO. In conclusion, these results indicate that the activation of p44/42 MAPK may favour the expression of ODC, and that polyamines, in turn, may affect the phosphorylation state of MAPK.
Flavio Flamigni - One of the best experts on this subject based on the ideXlab platform.
-
control of survival of proliferating L1210 Cells by soluble guanylate cyclase and p44 42 mitogen activated protein kinase modulators
Biochemical Pharmacology, 2001Co-Authors: Flavio Flamigni, A Facchini, Benedetta Tantini, Ivana Stanic, Francesca Bonavita, Claudio StefanelliAbstract:Abstract Intracellular signaling pathways involved in the survival of proliferating L1210 leukemia Cells were investigated by using specific modulators. Among the various inhibitors tested, only 1H-[1,2,4]oxadiazole [4,3-a]quinoxalin-1-one (ODQ), a soluble guanylate cyclase (sGC) inhibitor, was found to induce a marked increase in caspase activity, which was associated with a loss of cell viability and a reduction in cGMP content. ODQ also provoked the processing of caspases-3 and -9, release of cytochrome c and, as early events, reduction of Bcl-2 content and dephosphorylation of Bad at Ser 112. Furthermore, YC-1, an sGC activator, and 8-Br-cGMP, a cell-permeant analogue of cGMP, exerted some protection against various apoptotic stimuli, such as serum deprivation or spermine accumulation. Although PD98059 (2′-amino-3′-methoxyflavone), an inhibitor of the p44/42 mitogen-activated protein kinase (MAPK) pathway, did not increase basal caspase activity, and ODQ did not affect p44/42 MAPK phosphorylation significantly, phorbol myristate acetate stimulated p44/42 MAPK and reduced caspase activation induced by ODQ, serum deprivation, and spermine in a p44/42-dependent manner. SB203580 (4-(4-fluorophenyl)-2-(4-methylsulfonylphenyl)-5-(4-pyridyl)1H-imidazole), a p38 MAPK inhibitor, also partially protected against ODQ-induced apoptosis by increasing p44/42 MAPK phosphorylation. In conclusion, these results suggest that sGC may be relevant both for survival of L1210 Cells under basal growing conditions and for protection against various apoptotic stimuli. p44/42 MAPK activation may also confer some protection from apoptosis, but apparently through a pathway largely independent of cGMP.
-
p44 42 mitogen activated protein kinase is involved in the expression of ornithine decarboxylase in leukaemia L1210 Cells
Biochemical Journal, 1999Co-Authors: Flavio Flamigni, A Facchini, Cristina Capanni, Claudio Stefanelli, Benedetta Tantini, C M CaldareraAbstract:The involvement of p44/42 mitogen-activated protein kinase (MAPK) in the induction of ornithine decarboxylase (ODC) was investigated by using PD98059, a specific MAPK-kinase (MEK1/2) inhibitor, and other signal-transduction inhibitors. In d,l-alpha-difluoromethylornithine (DFMO)-resistant L1210 Cells stimulated to grow from quiescence, treatment with PD98059 inhibited p44/42 MAPK phosphorylation and the induction of ODC activity and protein. A marked reduction of the accumulation of mature ODC mRNA and its intron-containing precursor was observed, whereas ODC turnover was hardly affected. PD98059 also reduced the content of antizyme, but not that of antizyme mRNA. U0126, a novel and more potent inhibitor of MEK1/2, provoked a dose-dependent inhibition of ODC induction at lower concentrations with respect to PD98059. Other effective inhibitors of ODC induction proved to be genistein, manumycin A, herbimycin A, LY294002, wortmannin and KT5823, suggesting the involvement of other key proteins of signal-transduction pathways, i.e. Ras, Src, phosphatidylinositol 3-kinase and cGMP-dependent protein kinase, which may have a positive impact on MAPK. Cells kept in a DFMO-free medium, and thus containing high levels of putrescine and spermidine, showed enhanced MAPK phosphorylation and lower sensitivity to PD98059, compared with Cells maintained in the presence of DFMO. In conclusion, these results indicate that the activation of p44/42 MAPK may favour the expression of ODC, and that polyamines, in turn, may affect the phosphorylation state of MAPK.
Zdenka Sulova - One of the best experts on this subject based on the ideXlab platform.
-
overexpression of grp78 bip in p glycoprotein positive L1210 Cells is responsible for altered response of Cells to tunicamycin as a stressor of the endoplasmic reticulum
Cells, 2020Co-Authors: Mario Seres, Albert Breier, Lucia Pavlikova, Viera Bohacova, Tomas Kyca, Ivana Borovska, Boris Lakatos, Zdenka SulovaAbstract:P-glycoprotein (P-gp, ABCB1 member of the ABC (ATP-binding cassette) transporter family) localized in leukemia cell plasma membranes is known to reduce cell sensitivity to a large but well-defined group of chemicals known as P-gp substrates. However, we found previously that P-gp-positive sublines of L1210 murine leukemia Cells (R and T) but not parental P-gp-negative parental Cells (S) are resistant to the endoplasmic reticulum (ER) stressor tunicamycin (an N-glycosylation inhibitor). Here, we elucidated the mechanism of tunicamycin resistance in P-gp-positive Cells. We found that tunicamycin at a sublethal concentration of 0.1 µM induced retention of the Cells in the G1 phase of the cell cycle only in the P-gp negative variant of L1210 Cells. P-gp-positive L1210 cell variants had higher expression of the ER stress chaperone GRP78/BiP compared to that of P-gp-negative Cells, in which tunicamycin induced larger upregulation of CHOP (C/EBP homologous protein). Transfection of the sensitive P-gp-negative Cells with plasmids containing GRP78/BiP antagonized tunicamycin-induced CHOP expression and reduced tunicamycin-induced arrest of Cells in the G1 phase of the cell cycle. Taken together, these data suggest that the resistance of P-gp-positive Cells to tunicamycin is due to increased levels of GRP78/BiP, which is overexpressed in both resistant variants of L1210 Cells.
-
L1210 Cells overexpressing abcb1 drug transporters are resistant to inhibitors of the n and o glycosylation of proteins
Molecules, 2017Co-Authors: Lucia Pavlikova, Mario Seres, Albert Breier, Milan Hano, Viera Bohacova, Ivana Sevcikova, Tomas Kyca, Zdenka SulovaAbstract:Overexpression of P-glycoprotein (P-gp, drug transporter) in neoplastic Cells is the most frequently observed molecular cause of multidrug resistance. Here, we show that the overexpression of P-gp in L1210 Cells leads to resistance to tunicamycin and benzyl 2-acetamido-2-deoxy-α-d-galactopyranoside (GalNAc-α-O-benzyl). Tunicamycin induces both glycosylation depression and ubiquitination improvement of P-gp. However, the latter is not associated with large increases in molecular mass as evidence for polyubiquitination. Therefore, P-gp continues in maturation to an active membrane efflux pump rather than proteasomal degradation. P-gp-positive L1210 Cells contain a higher quantity of ubiquitin associated with cell surface proteins than their P-gp-negative counterparts. Thus, P-gp-positive Cells use ubiquitin signaling for correct protein folding to a higher extent than P-gp-negative Cells. Elevation of protein ubiquitination after tunicamycin treatment in these Cells leads to protein folding rather than protein degradation, resulting at least in the partial lack of cell sensitivity to tunicamycin in L1210 Cells after P-gp expression. In contrast to tunicamycin, to understand why P-gp-positive Cells are resistant to GalNAc-α-O-benzyl, further research is needed.
-
effect of 9 cis retinoic acid and all trans retinoic acid in combination with verapamil on p glycoprotein expression in L1210 Cells
Neoplasma, 2014Co-Authors: Albert Breier, J Stetka, V Bohacova, D Macejova, J Brtko, Zdenka SulovaAbstract:The development of the most common multidrug resistance (MDR) phenotype is associated with a massive overexpression of P-glycoprotein (P-gp) in neoplastic Cells. In the current study, we used three L1210 cell variants: S Cells - parental drug-sensitive Cells; R Cells - drug-resistant Cells with P-gp overexpression due to selection with vincristine; T Cells - drug-resistant Cells with P-gp overexpression due to stable transfection with the pHaMDRwt plasmid, which encodes human full-length P-gp. Several authors have described the induction of P-gp expression/activity in malignant cell lines after treatment with all-trans retinoic acid (AtRA; ligand of retinoic acid nuclear receptors, RARs). An isomer of AtRA also exists, 9-cis retinoic acid, which is a ligand of both RARs and nuclear retinoid X receptors (RXRs). In a previous work, we described that the combined treatment of R Cells with verapamil and AtRA induces the downregulation of P-gp expression/activity. In the current study, we studied the expression of RARs and RXRs in S, R and T Cells and the effects of treatment with AtRA, 9cRA and verapamil on P-gp expression, cellular localization and efflux activity in R and T Cells. We found that the overexpression of P-gp in L1210 Cells is associated with several changes in the specific transcription of both subgroups of nuclear receptors, RARs and RXRs. We also demonstrated that treatment with AtRA, 9cRA and verapamil induces alterations in P-gp expression in R and T Cells. Particularly, combined treatment of R Cells with verapamil and AtRA induced downregulation of P-gp content/activity. In contrast, similar treatment of T Cells induced slight increase of P-gp content without any changes in efflux activity of this protein. These findings indicate that active crosstalk between the RAR and RXR regulatory pathways and P-gp-mediated MDR could take place.
-
p glycoprotein depresses cisplatin sensitivity in L1210 Cells by inhibiting cisplatin induced caspase 3 activation
Toxicology in Vitro, 2012Co-Authors: Lenka Gibalova, J Sedlak, Mario Seres, Albert Breier, B Uhrik, Andrej Rusnak, Peter Ditte, Martina Labudova, Jaromir Pastorek, Zdenka SulovaAbstract:Multidrug resistance (MDR) is a phenomenon in which Cells become resistant to cytostatic drugs and other substances with diverse chemical structures and cytotoxicity mechanisms. The most often observed molecular mechanism for MDR includes high levels of P-glycoprotein (P-gp)--an ABCB1 member of the ABC drug transporter family. Overexpression of P-gp in neoplastic tissue is an obstacle to chemotherapeutic treatment. Herein, we were focused on differences in apoptosis induced by cisplatin (no substrate for P-gp) between P-gp-positive and P-gp-negative L1210 Cells. P-gp-positive Cells were obtained by either L1210 cell adaptation to vincristine (R) or L1210 cell transfection with the human gene for P-gp (T) and compared with parental L1210 Cells (S). R and T Cells were more resistant to CisPt than S Cells. R and T cell resistance to CisPt-induced apoptosis could not be reversed by verapamil (a well-known P-gp inhibitor), which excludes P-gp transport activity as a cause of CisPt resistance. CisPt induced a more pronounced entry into apoptosis in S than R and T Cells, which was measured using the annexin-V/propidium iodide apoptosis kit. CisPt induced more pronounced caspase-3 activation in S than R and T Cells. CisPt did not induce changes in the P-gp protein level for R and T Cells. While similar levels of Bax and Bcl-2 proteins were observed in P-gp-negative and P-gp-positive Cells, CisPt induced a more significant decrease in Bcl-2 levels for S Cells than P-gp-positive Cells. Expression of p53 and its molecular chaperone Hsp90 were more pronounced in R and T than S Cells. Moreover, CisPt enhanced the upregulation of p53 and Hsp90 in R and T Cells to a higher degree than S Cells. Apoptosis was shown to be the prevalent mode of cell death in S, R and T Cells by the typical DNA fragmentation and cell ultrastructure changes. All of the above findings indicate that P-gp, independent of its drug efflux activity, induced changes in cell regulatory pathways that confer a partial loss of cisplatin sensitivity.
-
tunicamycin depresses p glycoprotein glycosylation without an effect on its membrane localization and drug efflux activity in L1210 Cells
International Journal of Molecular Sciences, 2011Co-Authors: Mario Seres, Dana Cholujova, Tatiana Bubencikova, Albert Breier, Zdenka SulovaAbstract:P-glycoprotein (P-gp), also known as ABCB1, is a member of the ABC transporter family of proteins. P-gp is an ATP-dependent drug efflux pump that is localized to the plasma membrane of mammalian Cells and confers multidrug resistance in neoplastic Cells. P-gp is a 140-kDa polypeptide that is glycosylated to a final molecular weight of 170 kDa. Our experimental model used two variants of L1210 Cells in which overexpression of P-gp was achieved: either by adaptation of parental Cells (S) to vincristine (R) or by transfection with the human gene encoding P-gp (T). R and T Cells were found to differ from S Cells in transglycosylation reactions in our recent studies. The effects of tunicamycin on glycosylation, drug efflux activity and cellular localization of P-gp in R and T Cells were examined in the present study. Treatment with tunicamycin caused less concentration-dependent cellular damage to R and T Cells compared with S Cells. Tunicamycin inhibited P-gp N-glycosylation in both of the P-gp-positive Cells. However, tunicamycin treatment did not alter either the P-gp cellular localization to the plasma membrane or the P-gp transport activity. The present paper brings evidence that independently on the mode of P-gp expression (selection with drugs or transfection with a gene encoding P-gp) in L1210 Cells, tunicamycin induces inhibition of N-glycosylation of this protein, without altering its function as plasma membrane drug efflux pump.
Quanhong Liu - One of the best experts on this subject based on the ideXlab platform.
-
the antitumor activity of meconopsis horridula hook a traditional tibetan medical plant in murine leukemia L1210 Cells
Cellular Physiology and Biochemistry, 2015Co-Authors: Jianping Fan, Pan Wang, Xiaobing Wang, Yaqin Wang, Wei Tang, Wenjuan Yuan, Lulu Kong, Quanhong LiuAbstract:Background: Meconopsis horridula Hook (M. horridula) has been used as a traditional Tibetan medicine to relieve heat and pain as well as mobilize static blood, and it is recognized as a good treatment for bruises. This study is the first trial to evaluate the tumor inhibitory activity of M. horridula extract and its underlying mechanism in the hope of providing evidence to support the anticancer function of M. horridula. Methods and Results: M. horridula extract was cytotoxic to L1210 Cells in a dose- and time-dependent manner. SEM (scanning electron microscope) observation revealed obvious morphological changes in L1210 Cells after M. horridula treatment. Flow cytometry analysis demonstrated that the extract dose-dependently induced early apoptosis. Additional apoptosis parameters, such as alterations in nuclear morphology and DNA damage, were also observed. Furthermore, M. horridula treatment induced G2/M arrest. M. horridula treatment significantly increased reactive oxygen species (ROS) production, suggesting that ROS are a key factor in M. horridula-induced apoptosis. Volatile constituent detection found 15 abundant chemicals in M. horridula, which may contribute to its anticancer effect. Conclusion: In conclusion, M. horridula extract induced L1210 cell apoptosis and inhibited proliferation through G2/M phase arrest, and ROS were involved in the process.
-
the ethyl acetate fraction of polytrichum commune l ex hedw induced cell apoptosis via reactive oxygen species in L1210 Cells
Journal of Ethnopharmacology, 2013Co-Authors: Xiaoxia Cheng, Pan Wang, Yuetao Zhou, Yaping Xiao, Xiaobing Wang, Han Yan, Quanhong LiuAbstract:Abstract Ethnopharmacological relevance Polytrichum commune L.ex Hedw is a traditional Chinese herb for treatment of fever, hemostatic, uterine prolapse and especially for leukemia. Previous studies indicated its anti-leukemia effect but the potential mechanisms have not been fully explained. Aims of the study The present study was further to investigate the underlying mechanism of ethyl acetate extract of Polytrichum commune L.ex Hedw (EEF)-induced toxicity and apoptosis in L1210 Cells. Materials and methods Viability, DNA damage and apoptotic protein expressions of L1210 Cells were analyzed by ViaCount, comet assay and western blot, respectively. At different times after EEF treatment, Bax redistribution in L1210 Cells was examined using confocal microscopy; loss of mitochondrial membrane potential (MMP) was monitored by fluorescence microscope using rhodamine 123 staining; Intracellular reactive oxygen species (ROS) generation and DNA fragmentation were measured by flow cytometry using fluorescent dye, DCFH-DA and PI, respectively. Results EEF significantly inhibited L1210 cell survival, promoted Bax translocation onto mitochondria, stimulated caspase-9 activation and subsequent DNA damage in L1210 Cells. Abundant ROS was detected in L1210 Cells after EEF treatment, and the ROS scavenger NAC significantly relieved EEF-induced cell viability decline, MMP loss, and DNA fragmentation. Conclusion EEF could induce mitochondria-dependent cell apoptosis in L1210 Cells, and ROS may play an important role in this action.
-
initiation of autophagy and apoptosis by sonodynamic therapy in murine leukemia L1210 Cells
Toxicology in Vitro, 2013Co-Authors: Xiaobing Wang, Pan Wang, Kun Zhang, Jie Hou, Quanhong LiuAbstract:Sonodynamic therapy (SDT) has shown great potential in target cancer therapy, but it induced cell death modes has not been fully investigated. This study was to examine autophagic and apoptotic responses to protoporphyrin IX (PpIX) mediated SDT in murine leukemia L1210 Cells. After SDT, the occurrence of autophagy was identified by morphological observation and biochemical analysis. Meanwhile, the mitochondria dependent apoptosis pathway was examined to participate in SDT induced cell death. The relationship between autophagy and apoptosis was further investigated by applying pharmacological inhibition studies, which indicated that impairment of autophagy enhanced the anti-tumor effect of SDT through induction of apoptosis and necrosis, while caspase inhibition did not affect autophagic vacuoles formation or protect SDT induced cytotoxicity. The findings supported that autophagic vacuoles formed upstream and independently from caspase-dependent cell death. Additionally, the possible mechanism of SDT-induced autophagy was evaluated by measurement of ROS (reactive oxygen species) formation. Result suggested ROS play important role in initiating autophagy, possibly through the sono-damaged mitochondria being enclosed by autophagic vacuoles. All together, these data indicate that autophagy may be cytoprotective in our experimental system, and point to an important insight into how autophagy inhibitors, in combination with SDT may contribute a regimen for cancer therapy.
-
cell cycle arrest and cell apoptosis induced by equisetum hyemale extract in murine leukemia L1210 Cells
Journal of Ethnopharmacology, 2012Co-Authors: Pan Wang, Quanhong Liu, Xiaoxia Cheng, Yuetao Zhou, Yaping XiaoAbstract:Abstract Ethnopharmacological relevance Equisetum hyemale has been used as a traditional herbal medicine to treat various diseases such as hypertension, inflammatory diseases, acute stroke, bleeding and cancer. The present study aimed to investigate the anti-proliferative effect and the underlying mechanisms of E.hyemale extract on murine leukemia L1210 Cells. Materials and methods The inhibitory effect of Ehyemale extract on L1210 Cells was evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Cell cycle distribution was evaluated with flow cytometry following PI (propidium iodide) staining. Apoptotic cell death was determined by Annexin V–FITC/PI and nuclear DAPI (4′-6-diamidino-2-phenylindole) staining. DNA damage and changes of mitochondrial membrane potential were also detected with flow cytometry analysis. Results E.hyemale extract exerted significant antiproliferative effects on L1210 Cells in a dose- and time-dependent manner. Flow cytometry analysis showed that E.hyemale extract induced cell cycle arrest at G2/M phase in L1210 Cells. Phosphatidylserine exposure, chromatin condensation, DNA damage and loss of mitochondrial membrane potential were observed clearly after treatment with Ehyemale extract. Conclusion The results in this study indicate that E.hyemale extract could inhibit L1210 cell proliferation through inducing G2/M arrest and cell apoptosis.
-
anti tumor and pro apoptotic activity of ethanolic extract and its various fractions from polytrichum commune l ex hedw in L1210 Cells
Journal of Ethnopharmacology, 2012Co-Authors: Xiaoxia Cheng, Pan Wang, Yaping Xiao, Xiaobing Wang, Han Yan, Quanhong LiuAbstract:Abstract Ethnopharmacological relevance Polytrichum commune L.ex Hedw is a traditional Chinese herb for treatment of fever, hemostatic, uterine prolapse and especially for lymphocytic leukemia, but the antitumor effect and its potential mechanism remains unclear. Aims of the study The present study was to investigate the possible anti-proliferative activity of ethanolic extract and the organic fractions from P. commune on murine leukemia L1210 Cells. Materials and methods The content of ethanolic extract and its fractions was performed on HPLC analysis with gradient elution. L1210 Cells were treated with different concentrations of ethanolic extract and its fractions at different time intervals. Cell viability was evaluated using MTT assay. Apoptotic cell death was monitored by nuclear condensation and confirmed by exposure of phosphatidylserine to outer leaflet of plasma membrane. Loss of mitochondrial membrane potential was analyzed by flow cytometry using rhodamine 123 staining. Results The obtained results showed that the cell viability of L1210 Cells was reduced by ethanolic extract of P. commune in a concentration-dependent manner, and the IC 50 value was about 77.22 μg/ml at 24 h post treatment. The ethylacetate fraction displayed higher anti-tumor effect than that of chloroform and butanol fractions with 32.29 μg/ml (IC 50 value, 48 h). Microscopy studies revealed that ethanolic extract and ethylacetate fraction treated Cells showed morphological characteristics of apoptosis such as chromatin condensation and DNA aggregation. Further, Annexin V-PE/ 7-AAD double staining showing the out leaflet of phosphatidylserine and the decline of mitochondrial membrane potential by flow cytometry confirmed that the extracts do, in fact, induce apoptosis in L1210 Cells. Conclusion This is the first report on anti-tumor and pro-apoptotic effect of P. commune in cultured leukemia Cells, which provides scientific basis for its usefulness as traditional medicine. Further studies are needed to confirm the precise mechanism not only the crude extract but as well the monomeric chemical substances of Polytrichum commune L.ex Hedw.
Benedetta Tantini - One of the best experts on this subject based on the ideXlab platform.
-
control of survival of proliferating L1210 Cells by soluble guanylate cyclase and p44 42 mitogen activated protein kinase modulators
Biochemical Pharmacology, 2001Co-Authors: Flavio Flamigni, A Facchini, Benedetta Tantini, Ivana Stanic, Francesca Bonavita, Claudio StefanelliAbstract:Abstract Intracellular signaling pathways involved in the survival of proliferating L1210 leukemia Cells were investigated by using specific modulators. Among the various inhibitors tested, only 1H-[1,2,4]oxadiazole [4,3-a]quinoxalin-1-one (ODQ), a soluble guanylate cyclase (sGC) inhibitor, was found to induce a marked increase in caspase activity, which was associated with a loss of cell viability and a reduction in cGMP content. ODQ also provoked the processing of caspases-3 and -9, release of cytochrome c and, as early events, reduction of Bcl-2 content and dephosphorylation of Bad at Ser 112. Furthermore, YC-1, an sGC activator, and 8-Br-cGMP, a cell-permeant analogue of cGMP, exerted some protection against various apoptotic stimuli, such as serum deprivation or spermine accumulation. Although PD98059 (2′-amino-3′-methoxyflavone), an inhibitor of the p44/42 mitogen-activated protein kinase (MAPK) pathway, did not increase basal caspase activity, and ODQ did not affect p44/42 MAPK phosphorylation significantly, phorbol myristate acetate stimulated p44/42 MAPK and reduced caspase activation induced by ODQ, serum deprivation, and spermine in a p44/42-dependent manner. SB203580 (4-(4-fluorophenyl)-2-(4-methylsulfonylphenyl)-5-(4-pyridyl)1H-imidazole), a p38 MAPK inhibitor, also partially protected against ODQ-induced apoptosis by increasing p44/42 MAPK phosphorylation. In conclusion, these results suggest that sGC may be relevant both for survival of L1210 Cells under basal growing conditions and for protection against various apoptotic stimuli. p44/42 MAPK activation may also confer some protection from apoptosis, but apparently through a pathway largely independent of cGMP.
-
p44 42 mitogen activated protein kinase is involved in the expression of ornithine decarboxylase in leukaemia L1210 Cells
Biochemical Journal, 1999Co-Authors: Flavio Flamigni, A Facchini, Cristina Capanni, Claudio Stefanelli, Benedetta Tantini, C M CaldareraAbstract:The involvement of p44/42 mitogen-activated protein kinase (MAPK) in the induction of ornithine decarboxylase (ODC) was investigated by using PD98059, a specific MAPK-kinase (MEK1/2) inhibitor, and other signal-transduction inhibitors. In d,l-alpha-difluoromethylornithine (DFMO)-resistant L1210 Cells stimulated to grow from quiescence, treatment with PD98059 inhibited p44/42 MAPK phosphorylation and the induction of ODC activity and protein. A marked reduction of the accumulation of mature ODC mRNA and its intron-containing precursor was observed, whereas ODC turnover was hardly affected. PD98059 also reduced the content of antizyme, but not that of antizyme mRNA. U0126, a novel and more potent inhibitor of MEK1/2, provoked a dose-dependent inhibition of ODC induction at lower concentrations with respect to PD98059. Other effective inhibitors of ODC induction proved to be genistein, manumycin A, herbimycin A, LY294002, wortmannin and KT5823, suggesting the involvement of other key proteins of signal-transduction pathways, i.e. Ras, Src, phosphatidylinositol 3-kinase and cGMP-dependent protein kinase, which may have a positive impact on MAPK. Cells kept in a DFMO-free medium, and thus containing high levels of putrescine and spermidine, showed enhanced MAPK phosphorylation and lower sensitivity to PD98059, compared with Cells maintained in the presence of DFMO. In conclusion, these results indicate that the activation of p44/42 MAPK may favour the expression of ODC, and that polyamines, in turn, may affect the phosphorylation state of MAPK.
