Latest Publications

@article{mickova_skp2_2021,

title = {Skp2 and Slug Are Coexpressed in Aggressive Prostate Cancer and Inhibited by Neddylation Blockade.},

author = {Alena Mickova and Gvantsa Kharaishvili and Daniela Kurfurstova and Mariam Gachechiladze and Milan Kral and Ondrej Vacek and Barbora Pokryvkova and Martin Mistrik and Karel Soucek and Jan Bouchal},

doi = {10.3390/ijms22062844},

issn = {1422-0067},

year  = {2021},

date = {2021-03-01},

journal = {International journal of molecular sciences},

volume = {22},

number = {6},

abstract = {Prostate cancer (PCa) is the second leading cause of cancer-related deaths in men in Western countries, and there is still an urgent need for a better understanding of PCa progression to inspire new treatment strategies. Skp2 is a substrate-recruiting component of the E3 ubiquitin ligase complex, whose activity is regulated through neddylation. Slug is a transcriptional repressor involved in the epithelial-to-mesenchymal transition, which may contribute to therapy resistance. Although Skp2 has previously been associated with a mesenchymal phenotype and prostate cancer progression, the relationship with Slug deserves further elucidation. We have previously shown that a high Gleason score (≥8) is associated with higher Skp2 and lower E-cadherin expression. In this study, significantly increased expression of Skp2, AR, and Slug, along with E-cadherin downregulation, was observed in primary prostate cancer in patients who already had lymph node metastases. Skp2 was slightly correlated with Slug and AR in the whole cohort (Rs 0.32 and 0.37, respectively), which was enhanced for both proteins in patients with high Gleason scores (Rs 0.56 and 0.53, respectively) and, in the case of Slug, also in patients with metastasis to lymph nodes (Rs 0.56). Coexpression of Skp2 and Slug was confirmed in prostate cancer tissues by multiplex immunohistochemistry and confocal microscopy. The same relationship between these two proteins was observed in three sets of prostate epithelial cell lines (PC3, DU145, and E2) and their mesenchymal counterparts. Chemical inhibition of Skp2, but not RNA interference, modestly decreased Slug protein in PC3 and its docetaxel-resistant subline PC3 DR12. Importantly, chemical inhibition of Skp2 by MLN4924 upregulated p27 and decreased Slug expression in PC3, PC3 DR12, and LAPC4 cells. Novel treatment strategies targeting Skp2 and Slug by the neddylation blockade may be promising in advanced prostate cancer, as recently documented for other aggressive solid tumors.},

note = {Place: Switzerland},

keywords = {*Protein Processing, Androgen/genetics/metabolism, Antigens, Antineoplastic Agents/pharmacology, Cadherins/genetics/metabolism, CD/genetics/metabolism, Cell Line, Cell Survival/drug effects, Cyclin-Dependent Kinase Inhibitor p27/genetics/metabolism, Cyclopentanes/pharmacology, Docetaxel/pharmacology, Epithelial-Mesenchymal Transition/genetics, Gene Expression Regulation, Humans, Immunohistochemistry, Lymphatic Metastasis, Male, multiplex, NEDD8 Protein/*genetics/metabolism, neddylation, Neoplasm Grading, Neoplastic, PC-3 Cells, Post-Translational, Prostate cancer, Prostate/metabolism/pathology, Prostatic Neoplasms/*genetics/metabolism/pathology, Pyrimidines/pharmacology, Receptors, RNA, S-Phase Kinase-Associated Proteins/antagonists & inhibitors/*genetics/metabolism, Skp2 (S-phase kinase-associated protein 2), Slug, Small Interfering/genetics/metabolism, Snail Family Transcription Factors/*genetics/metabolism, Tumor},

pubstate = {published},

tppubtype = {article}

}

@article{kauerova_ring-substituted_2020,

title = {Ring-Substituted 1-Hydroxynaphthalene-2-Carboxanilides Inhibit Proliferation and Trigger Mitochondria-Mediated Apoptosis.},

author = {Tereza Kauerová and Tomáš Goněc and Josef Jampílek and Susanne Hafner and Ann-Kathrin Gaiser and Tatiana Syrovets and Radek Fedr and Karel Souček and Peter Kollar},

doi = {10.3390/ijms21103416},

issn = {1422-0067},

year  = {2020},

date = {2020-05-01},

journal = {International journal of molecular sciences},

volume = {21},

number = {10},

abstract = {Ring-substituted 1-hydroxynaphthalene-2-carboxanilides were previously investigated for their antimycobacterial properties. In our study, we have shown their antiproliferative and cell death-inducing effects in cancer cell lines. Cell proliferation and viability were assessed by WST-1 assay and a dye exclusion test, respectively. Cell cycle distribution, phosphatidylserine externalization, levels of reactive oxygen or nitrogen species (RONS), mitochondrial membrane depolarization, and release of cytochrome c were estimated by flow cytometry. Levels of regulatory proteins were determined by Western blotting. Our data suggest that the ability to inhibit the proliferation of THP-1 or MCF-7 cells might be referred to meta- or para-substituted derivatives with electron-withdrawing groups -F, -Br, or -CF(3) at anilide moiety. This effect was accompanied by accumulation of cells in G1 phase. Compound 10 also induced apoptosis in THP-1 cells in association with a loss of mitochondrial membrane potential and production of mitochondrial superoxide. Our study provides a new insight into the action of salicylanilide derivatives, hydroxynaphthalene carboxamides, in cancer cells. Thus, their structure merits further investigation as a model moiety of new small-molecule compounds with potential anticancer properties.},

note = {Place: Switzerland},

keywords = {Anilides/chemistry/*pharmacology, Antineoplastic Agents/chemistry/pharmacology, antiproliferative effect, Apoptosis, Apoptosis/*drug effects, Cell Cycle, Cell Cycle/drug effects, Cell Proliferation/*drug effects, Cell Survival/drug effects, Humans, hydroxynaphthalene carboxamides, MCF-7 Cells, Membrane Potential, Mitochondria/*drug effects/metabolism, Mitochondrial/drug effects, Molecular Structure, Naphthols/*chemistry, Reactive Oxygen Species/metabolism, salicylanilides, Salicylanilides/chemistry/pharmacology, Structure-Activity Relationship, Superoxides/metabolism, THP-1 Cells},

pubstate = {published},

tppubtype = {article}

}

@article{nemec_furo32-bpyridine_2019,

title = {Furo[3,2-b]pyridine: A Privileged Scaffold for Highly Selective Kinase Inhibitors and Effective Modulators of the Hedgehog Pathway.},

author = {Václav Němec and Michaela Hylsová and Lukáš Maier and Jana Flegel and Sonja Sievers and Slava Ziegler and Martin Schröder and Benedict-Tilman Berger and Apirat Chaikuad and Barbora Valčíková and Stjepan Uldrijan and Stanislav Drápela and Karel Souček and Herbert Waldmann and Stefan Knapp and Kamil Paruch},

doi = {10.1002/anie.201810312},

issn = {1521-3773 1433-7851},

year  = {2019},

date = {2019-01-01},

journal = {Angewandte Chemie (International ed. in English)},

volume = {58},

number = {4},

pages = {1062–1066},

abstract = {Reported is the identification of the furo[3,2-b]pyridine core as a novel scaffold for potent and highly selective inhibitors of cdc-like kinases (CLKs) and efficient modulators of the Hedgehog signaling pathway. Initially, a diverse target compound set was prepared by synthetic sequences based on chemoselective metal-mediated couplings, including assembly of the furo[3,2-b]pyridine scaffold by copper-mediated oxidative cyclization. Optimization of the subseries containing 3,5-disubstituted furo[3,2-b]pyridines afforded potent, cell-active, and highly selective inhibitors of CLKs. Profiling of the kinase-inactive subset of 3,5,7-trisubstituted furo[3,2-b]pyridines revealed sub-micromolar modulators of the Hedgehog pathway.},

note = {Place: Germany},

keywords = {Binding Sites, biological activity, Cell Survival/drug effects, chemical probes, Furans/*chemistry, Hedgehog Proteins/*chemistry, heterocycles, Humans, inhibitors, Inhibitory Concentration 50, kinases, MCF-7 Cells, Molecular Structure, Protein Binding, Protein Kinase Inhibitors/*chemical synthesis/chemistry/pharmacology, Pyridines/*chemistry, Small Molecule Libraries/*chemical synthesis/chemistry/pharmacology},

pubstate = {published},

tppubtype = {article}

}

@article{herudkova_chk1_2017,

title = {Chk1 Inhibitor SCH900776 Effectively Potentiates the Cytotoxic Effects of Platinum-Based Chemotherapeutic Drugs in Human Colon Cancer Cells.},

author = {Jarmila Herůdková and Kamil Paruch and Prashant Khirsariya and Karel Souček and Martin Krkoška and Olga Vondálová Blanářová and Petr Sova and Alois Kozubík and Alena Hyršlová Vaculová},

doi = {10.1016/j.neo.2017.08.002},

issn = {1476-5586 1522-8002},

year  = {2017},

date = {2017-10-01},

journal = {Neoplasia (New York, N.Y.)},

volume = {19},

number = {10},

pages = {830–841},

abstract = {Although Chk1 kinase inhibitors are currently under clinical investigation as effective cancer cell sensitizers to the cytotoxic effects of numerous chemotherapeutics, there is still a considerable uncertainty regarding their role in modulation of anticancer potential of platinum-based drugs. Here we newly demonstrate the ability of one of the most specific Chk1 inhibitors, SCH900776 (MK-8776), to enhance human colon cancer cell sensitivity to the cytotoxic effects of platinum(II) cisplatin and platinum(IV)- LA-12 complexes. The combined treatment with SCH900776 and cisplatin or LA-12 results in apparent increase in G1/S phase-related apoptosis, stimulation of mitotic slippage, and senescence of HCT116 cells. We further show that the cancer cell response to the drug combinations is significantly affected by the p21, p53, and PTEN status. In contrast to their wt counterparts, the p53- or p21-deficient cells treated with SCH900776 and cisplatin or LA-12 enter mitosis and become polyploid, and the senescence phenotype is strongly suppressed. While the cell death induced by SCH900776 and cisplatin or LA-12 is significantly delayed in the absence of p53, the anticancer action of the drug combinations is significantly accelerated in p21-deficient cells, which is associated with stimulation of apoptosis beyond G2/M cell cycle phase. We also show that cooperative killing action of the drug combinations in HCT116 cells is facilitated in the absence of PTEN. Our results indicate that SCH900776 may act as an important modulator of cytotoxic response triggered by platinum-based drugs in colon cancer cells.},

note = {Place: United States},

keywords = {Antineoplastic Agents/*pharmacology, Apoptosis/drug effects, Cell Cycle/drug effects/genetics, Cell Line, Cell Survival/drug effects, Cellular Senescence/drug effects, Checkpoint Kinase 1/*antagonists & inhibitors/genetics/*metabolism, Cisplatin/pharmacology, Colonic Neoplasms/drug therapy/genetics/*metabolism/pathology, Cyclin-Dependent Kinase Inhibitor p21/genetics/metabolism, DNA Damage/drug effects, Gene Knockout Techniques, Humans, Platinum Compounds/*pharmacology, Pyrazoles/*pharmacology, Pyrimidines/*pharmacology, Tumor, Tumor Suppressor Protein p53/genetics/metabolism},

pubstate = {published},

tppubtype = {article}

}

@article{gabelova_genotoxicity_2011,

title = {Genotoxicity of 7H-dibenzo[c,g]carbazole and its tissue-specific derivatives in human hepatoma HepG2 cells is related to CYP1A1/1A2 expression.},

author = {Alena Gábelová and Zuzana Valovičová and Monika Mesárošová and Lenka Trilecová and Eva Hrubá and Soňa Marvanová and Pavel Krčmár and Alena Milcová and Jana Schmuczerová and Jan Vondráček and Miroslav Machala and Jan Topinka},

doi = {10.1002/em.20664},

issn = {1098-2280 0893-6692},

year  = {2011},

date = {2011-10-01},

journal = {Environmental and molecular mutagenesis},

volume = {52},

number = {8},

pages = {636–645},

abstract = {The goal of this study was to investigate the genotoxicity of 7H-dibenzo[c,g]carbazole (DBC), a ubiquitous environmental pollutant, and its methyl derivatives, 5,9-dimethylDBC (DiMeDBC), a strict hepatocarcinogen, and N-methylDBC (N-MeDBC), a specific sarcomagen in human hepatoma HepG2 cells, and to infer potential mechanisms underlying the biological activity of particular carcinogen. All dibenzocarbazoles, regardless the tissue specificity, induced significant DNA strand break levels and micronuclei in HepG2 cells; though a mitotic spindle dysfunction rather than a chromosome breakage was implicated in N-MeDBC-mediated micronucleus formation. While DBC and N-MeDBC produced stable DNA adducts followed with p53 protein phosphorylation at Ser-15, DiMeDBC failed. A significant increase in DNA strand breaks following incubation of exposed cells with a repair-specific endonuclease (Fpg protein) suggested that either oxidative DNA damage or unstable DNA-adducts might underlie DiMeDBC genotoxicity in human hepatoma cells. DiMeDBC and N-MeDBC increased substantially also the amount of CYP1A1/2 expression in HepG2 cells. Pretreatment of cells with substances affecting AhR-mediated CYP1A family of enzymes expression; however, diminished DiMeDBC and N-MeDBC genotoxicity. Our data clearly demonstrated differences in the mechanisms involved in the biological activity of DiMeDBC and N-MeDBC in human hepatoma cells; the genotoxicity of these DBC derivatives is closely related to CYP1A1/2 expression.},

note = {Place: United States},

keywords = {Base Sequence, Blotting, Carbazoles/*toxicity, Cell Survival/drug effects, Chromosome-Defective/chemically induced/statistics & numerical data, Comet assay, Cytochrome P-450 CYP1A1/*genetics, Cytochrome P-450 CYP1A2/*genetics, DNA adducts, DNA Breaks, Dose-Response Relationship, Drug, Hep G2 Cells, Histones/metabolism, Humans, Micronuclei, Micronucleus Tests, Mitotic Index, Molecular Sequence Data, Mutagens/*toxicity, Phosphorylation, Real-Time Polymerase Chain Reaction, Tumor Suppressor Protein p53/metabolism, Western},

pubstate = {published},

tppubtype = {article}

}

@article{benes_inhibition_2011,

title = {Inhibition of topoisomerase IIα: novel function of wedelolactone.},

author = {Petr Benes and Lucia Knopfova and Filip Trcka and Alice Nemajerova and Diana Pinheiro and Karel Soucek and Miroslav Fojta and Jan Smarda},

doi = {10.1016/j.canlet.2011.01.002},

issn = {1872-7980 0304-3835},

year  = {2011},

date = {2011-04-01},

journal = {Cancer letters},

volume = {303},

number = {1},

pages = {29–38},

abstract = {The naturally occurring coumestan wedelolactone has been previously shown to reduce growth of various cancer cells. So far, the growth-suppressing effect of wedelolactone has been attributed to the inhibition of the NFκB transcription factor and/or androgen receptors. We found that wedelolactone suppressed growth and induced apoptosis of androgen receptor-negative MDA-MB-231 breast cancer cells at concentrations that did not inhibit the NFκB activity. The cells responded to wedelolactone by the S and G2/M phase cell cycle arrest and induction of the DNA damage signaling. Wedelolactone interacted with dsDNA and inhibited the activity of DNA topoisomerase IIα. We conclude that wedelolactone can act as growth suppressor independently of NFκB and androgen receptors.},

note = {Place: Ireland},

keywords = {Antigens, Antineoplastic Agents/pharmacology, Apoptosis/drug effects, Breast Neoplasms/*drug therapy/enzymology/pathology, Cell Cycle/drug effects, Cell Growth Processes/drug effects, Cell Line, Cell Survival/drug effects, Coumarins/*pharmacology, DNA Damage, DNA Topoisomerases, DNA-Binding Proteins/*antagonists & inhibitors/metabolism, Enzyme-Linked Immunosorbent Assay, Female, Humans, Immunoblotting, Neoplasm/metabolism, Signal Transduction, Topoisomerase Inhibitors/*pharmacology, Tumor, Type II/metabolism},

pubstate = {published},

tppubtype = {article}

}

@article{soucek_growthdifferentiation_2010,

title = {Growth/differentiation factor-15 is an abundant cytokine in human seminal plasma.},

author = {Karel Soucek and Eva Slabáková and Petra Ovesná and Alice Malenovská and Alois Kozubík and Ales Hampl},

doi = {10.1093/humrep/deq264},

issn = {1460-2350 0268-1161},

year  = {2010},

date = {2010-12-01},

journal = {Human reproduction (Oxford, England)},

volume = {25},

number = {12},

pages = {2962–2971},

abstract = {BACKGROUND: Transforming growth factor-β cytokines have various biological effects in female reproductive tissue, including modulation of inflammatory response and induction of immune tolerance to seminal antigens in the reproductive tract. However, no studies have analyzed the presence of growth/differentiation factor-15 (GDF-15/macrophage inhibitory cytokine-1) in seminal fluid or demonstrated the quantity and form of GDF-15, its possible role or the relationship between its concentration and semen quality. METHODS: The form and the concentration of GDF-15 were determined in 53 seminal plasma samples of both fertile and infertile men by ELISA and western blot. The sperm cells of three volunteers were treated with recombinant GDF-15, and cell viability and apoptosis were assessed by flow cytometry. The effect of GDF-15 on vaginal epithelial cells and peripheral blood mononuclear cells (PBMCs) was analyzed by quantitative RT-PCR. RESULTS: The GDF-15 concentration in seminal plasma ranged from 0.2 to 6.6 μg/ml as determined by ELISA. Western blot analysis revealed that GDF-15 is present in the active form. In vitro cultivation of sperm cells with GDF-15 did not affect their viability or rates of apoptosis; however, it did inhibit proliferation of PBMCs and induce expression of FOXP3 in CD4+CD25+ cells. CONCLUSIONS: To the best of our knowledge, this is the first demonstration that GDF-15 is an abundant cytokine in seminal plasma, although its concentration is not associated with semen quality or the fertility/infertility status of the donors. Moreover, our data show that GDF-15 displays immunosuppressive characteristics.},

note = {Place: England},

keywords = {Adult, Apoptosis/drug effects, CD4-Positive T-Lymphocytes/metabolism, Cell Proliferation/drug effects, Cell Survival/drug effects, Epithelial Cells/metabolism, Female, Forkhead Transcription Factors/biosynthesis, Growth Differentiation Factor 15/*physiology, Humans, Interleukin-2 Receptor alpha Subunit/metabolism, Leukocytes, Male, Middle Aged, Mononuclear/drug effects, Semen Analysis, Semen/*metabolism, Spermatozoa},

pubstate = {published},

tppubtype = {article}

}

@article{vaculova_different_2006,

title = {Different modulation of TRAIL-induced apoptosis by inhibition of pro-survival pathways in TRAIL-sensitive and TRAIL-resistant colon cancer cells.},

author = {Alena Vaculová and Jirina Hofmanová and Karel Soucek and Alois Kozubík},

doi = {10.1016/j.febslet.2006.11.004},

issn = {0014-5793},

year  = {2006},

date = {2006-12-01},

journal = {FEBS letters},

volume = {580},

number = {28-29},

pages = {6565–6569},

abstract = {Epithelial cells can be manipulated to undergo apoptosis depending on the balance between pro-survival and apoptotic signals. We showed that TRAIL-induced apoptosis may be differentially regulated by inhibitors of MEK ERK (U0126) or PI3K/Akt (LY294002) pathway in TRAIL-sensitive (HT-29) and TRAIL-resistant (SW620) human epithelial colon cancer cells. U0126 or LY294002 significantly enhanced TRAIL-induced apoptosis in HT-29 cells, but not in SW620 cells. We report a different regulation of the level of an anti-apoptotic Mcl-1 protein under MEK/ERK or PI3K/Akt pathway inhibition and suggest the mechanisms involved. A special attention was paid to the role of the ERK1/2, Akt, and glycogen synthase kinase 3beta.},

note = {Place: England},

keywords = {Apoptosis/*drug effects, Caspase 8/metabolism, Cell Survival/drug effects, Colonic Neoplasms/*pathology, Enzyme Activation/drug effects, Enzyme Inhibitors/pharmacology, Extracellular Signal-Regulated MAP Kinases/antagonists & inhibitors, Glycogen Synthase Kinase 3 beta, Glycogen Synthase Kinase 3/metabolism, HT29 Cells, Humans, Keratin-18/metabolism, Mitogen-Activated Protein Kinase 1/antagonists & inhibitors, Mitogen-Activated Protein Kinase 3/antagonists & inhibitors, Mitogen-Activated Protein Kinase Kinases/antagonists & inhibitors, Myeloid Cell Leukemia Sequence 1 Protein, Neoplasm Proteins/metabolism, Phosphoinositide-3 Kinase Inhibitors, Phosphorylation/drug effects, Poly(ADP-ribose) Polymerases/metabolism, Proto-Oncogene Proteins c-akt/antagonists & inhibitors, Proto-Oncogene Proteins c-bcl-2/metabolism, TNF-Related Apoptosis-Inducing Ligand/*pharmacology},

pubstate = {published},

tppubtype = {article}

}

@article{soucek_transforming_2006,

title = {Transforming growth factor-beta1 inhibits all-trans retinoic acid-induced apoptosis.},

author = {Karel Soucek and Jirí Pacherník and Lukás Kubala and Jan Vondrácek and Jirina Hofmanová and Alois Kozubík},

doi = {10.1016/j.leukres.2005.09.007},

issn = {0145-2126},

year  = {2006},

date = {2006-05-01},

journal = {Leukemia research},

volume = {30},

number = {5},

pages = {607–623},

abstract = {The interaction between retinoids and transforming growth factor-beta1 (TGF-beta1) leading to regulation of proliferation, differentiation and apoptosis is not still fully understood. In this study, we demonstrated that a combination treatment with all-trans retinoic acid (ATRA) and TGF-beta1 led to the enhancement of ATRA-induced suppression of cell proliferation, which is accompanied by inhibition of ATRA-induced apoptosis in human leukemia HL-60 cells. This effect was preceded by the arrest of cells in G0/G1 cell cycle phase linked with pRb protein dephosphorylation, continuous accumulation of p21 and transiently increased level of p27, inhibitors of cyclin-dependent kinases. Inhibition of ATRA-induced apoptosis by TGF-beta1 was associated with an increased level of Mcl-1 protein, an anti-apoptotic member of Bcl-2 family, but not with inhibition of mitochondrial membrane depolarization. Levels of other Bcl-2 family proteins (Bcl-2, Bcl-X(L), Bad, Bak, Bax) were unaffected by simultaneous ATRA and TGF-beta1 treatment, when compared to ATRA alone. Upregulation of c-FLIP(L) protein, an inhibitor of apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), correspond with inhibition of ATRA-induced (autocrine TRAIL-mediated) caspase-8 activation and apoptosis. These results suggest that apoptosis inhibition associated with proliferation block could depend on modulation of the TRAIL apoptotic pathway and regulation of the Mcl-1 protein level. In summary, we demonstrate that the balance of processes leading to regulation of proliferation and differentiation of myeloid cells can modulate cell sensitivity to apoptosis-inducing stimuli.},

note = {Place: England},

keywords = {Apoptosis Regulatory Proteins/metabolism/pharmacology, Apoptosis/*drug effects/physiology, bcl-2-Associated X Protein/drug effects/metabolism, CASP8 and FADD-Like Apoptosis Regulating Protein, Caspase 3, Caspase 8, Caspases/drug effects/metabolism, CD11b Antigen/biosynthesis/drug effects, Cell Cycle/drug effects, Cell Differentiation/drug effects, Cell Proliferation/drug effects, Cell Survival/drug effects, Cultured, Cyclin-Dependent Kinase Inhibitor p21/biosynthesis/drug effects, Drug Synergism, Enzyme Activation/drug effects, G1 Phase/drug effects, Granulocytes/drug effects/physiology, HL-60 Cells, Humans, Intracellular Signaling Peptides and Proteins/drug effects/metabolism, Membrane Glycoproteins/metabolism/pharmacology, Mitochondrial Membranes/drug effects/physiology, Myeloid Cell Leukemia Sequence 1 Protein, Neoplasm Proteins/drug effects/metabolism, Phosphorylation, Proto-Oncogene Proteins c-bcl-2/drug effects/metabolism, Reactive Oxygen Species/metabolism, Resting Phase, Retinoblastoma Protein/drug effects/metabolism, TNF-Related Apoptosis-Inducing Ligand, Transforming Growth Factor beta/*pharmacology, Transforming Growth Factor beta1, Tretinoin/*antagonists & inhibitors/pharmacology, Tumor Cells, Tumor Necrosis Factor-alpha/metabolism/pharmacology},

pubstate = {published},

tppubtype = {article}

}

@article{pliskova_effects_2005,

title = {Effects of silymarin flavonolignans and synthetic silybin derivatives on estrogen and aryl hydrocarbon receptor activation.},

author = {Martina Plísková and Jan Vondrácek and Vladimír Kren and Radek Gazák and Petr Sedmera and Daniela Walterová and Jitka Psotová and Vilím Simánek and Miroslav Machala},

doi = {10.1016/j.tox.2005.06.020},

issn = {0300-483X},

year  = {2005},

date = {2005-11-01},

journal = {Toxicology},

volume = {215},

number = {1-2},

pages = {80–89},

abstract = {Silymarin, a standardized mixture of flavonolignans, or its major constituents could be effective for prevention and treatment of hepatic damage or skin cancer. However, their potential side effects, such as modulation of endocrine functions via the disruption of estrogen receptor (ER) and/or aryl hydrocarbon receptor (AhR) activation, are largely unknown. In the present study, we investigated impact of silymarin, its constituents and a series of their synthetic derivatives on ER- and AhR-mediated activities using in vitro reporter gene assays. We found that none of the compounds under study affected the AhR-mediated activity in rat hepatoma cells. Contrary to that, several compounds behaved as either partial or full ER agonists. Silymarin elicited partial ER activation, with silybin B being probably responsible for a majority of the weak ER-mediated activity of silymarin; silybin A and other flavonolignans were found to be inactive and potent ER agonist taxifolin is only a minor constituent of silymarin. To our knowledge, this is probably the first time, when receptor-specific in vitro effects of separated diastereomers have been demonstrated. In contrast to silymarin constituents, the synthetic silybin derivatives, potentially useful as chemoprotective agents, did not modulate the ER-mediated activity, with exception of 23-O-pivaloylsilybin. Interestingly, 7-O-benzylsilybin potentiated ER-mediated activity of 17beta-estradiol despite possessing no estrogenic activity. In conclusion, our data suggest that estrogenicity of some silymarin constituents should be taken in account as their potential side effect when considered as chemopreventive compounds. These results also stress the need to study biological activities of purified or synthesized diastereomers of silybin derivatives.},

note = {Place: Ireland},

keywords = {Animals, Aryl Hydrocarbon/*metabolism, Cell Line, Cell Survival/drug effects, Dose-Response Relationship, Drug, Estrogen/*metabolism, Humans, Luciferases/biosynthesis/genetics, Molecular Structure, Rats, Receptors, Silybin, Silymarin/chemistry/pharmacology, Stereoisomerism, Tumor},

pubstate = {published},

tppubtype = {article}

}

@article{pliskova_deregulation_2005,

title = {Deregulation of cell proliferation by polycyclic aromatic hydrocarbons in human breast carcinoma MCF-7 cells reflects both genotoxic and nongenotoxic events.},

author = {Martina Plísková and Jan Vondrácek and Borivoj Vojtesek and Alois Kozubík and Miroslav Machala},

doi = {10.1093/toxsci/kfi040},

issn = {1096-6080 1096-0929},

year  = {2005},

date = {2005-02-01},

journal = {Toxicological sciences : an official journal of the Society of Toxicology},

volume = {83},

number = {2},

pages = {246–256},

abstract = {Polycyclic aromatic hydrocarbons (PAHs), such as benzo[a]pyrene (BaP), are carcinogens suggested to be involved in development of human cancer. Several recent studies have reported that PAHs can activate estrogen receptors (ER), either directly or indirectly by producing estrogenic metabolites. We hypothesized that the activation of ER by PAHs or their metabolites could induce cell proliferation in estrogen-sensitive cells. In the present study, we found that two PAHs, benz[a]anthracene (BaA) and BaP, can stimulate proliferation of human breast carcinoma MCF-7 cells at concentrations 100 nM and higher. This effect was ER-dependent, because it was blocked by the pure antiestrogen ICI 182,780. Although both PAHs partially inhibited S-phase entry and DNA synthesis induced by 17beta-estradiol, they stimulated S-phase entry when applied to MCF-7 cells synchronized by serum deprivation. This was in contrast with model antiestrogenic aryl hydrocarbon receptor ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin, which fully suppressed S-phase entry. BaP, which is a strong mutagen, was found to induce p53 tumor suppressor expression, a partial S-phase arrest and at higher concentrations also cell death. Pifithrin-alpha, a synthetic inhibitor of p53 activity, abolished both S-phase arrest and apoptosis induced by genotoxic PAHs, and it potentiated the proliferative effect of BaP. Thus, both genotoxic and nongenotoxic events seem to interact in the effects of BaP on cell proliferation. Taken together, our data indicate that both BaA and BaP can stimulate cell proliferation through activation of ER. The proliferative effects of these carcinogenic compounds might contribute to tumor promotion in estrogen-sensitive tissues.},

note = {Place: United States},

keywords = {Benz(a)Anthracenes/*toxicity, Benzo(a)pyrene/*toxicity, Benzothiazoles, Breast Neoplasms/drug therapy/*genetics/metabolism, Bromodeoxyuridine/metabolism, Carcinogens/*toxicity, Carcinoma/drug therapy/*genetics/metabolism, Cell Cycle/drug effects, Cell Line, Cell Proliferation/*drug effects, Cell Survival/drug effects, DNA Replication/drug effects, Dose-Response Relationship, Drug, Drug Interactions, Epigenesis, Estradiol/*analogs & derivatives/pharmacology, Estrogen, Estrogen Antagonists/pharmacology, Female, Fulvestrant, Genetic, Humans, Receptors, Thiazoles/pharmacology, Toluene/*analogs & derivatives/pharmacology, Tumor, Tumor Suppressor Protein p53/antagonists & inhibitors/genetics/metabolism},

pubstate = {published},

tppubtype = {article}

}

@article{machala_toxicity_2004,

title = {Toxicity of hydroxylated and quinoid PCB metabolites: inhibition of gap junctional intercellular communication and activation of aryl hydrocarbon and estrogen receptors in hepatic and mammary cells.},

author = {Miroslav Machala and Ludek Bláha and Hans-Joachim Lehmler and Martina Plísková and Zuzana Májková and Petra Kapplová and Iva Sovadinová and Jan Vondrácek and Tina Malmberg and Larry W. Robertson},

doi = {10.1021/tx030034v},

issn = {0893-228X},

year  = {2004},

date = {2004-03-01},

journal = {Chemical research in toxicology},

volume = {17},

number = {3},

pages = {340–347},

abstract = {In the present study, a series of 32 hydroxy- and dihydroxy-polychlorinated biphenyls (OH-PCBs) and PCB-derived quinones were prepared and evaluated for their in vitro potencies to downregulate gap junctional intercellular communication (GJIC) and to activate the aryl hydrocarbon receptor (AhR) and the estrogen receptor alpha (ER) in well-established liver and mammary cell models. The rat liver epithelial cell line WB-F344 was used for in vitro determination of GJIC inhibition; the AhR-inducing activity was determined in the rat hepatoma H4IIE.Luc cells stably transfected with a luciferase reporter gene; ER-mediated activity was measured in two breast carcinoma cell lines, MVLN and T47D.Luc, stably transfected with luciferase under the control of estrogen responsive element. Acute inhibition of GJIC, potentially associated with tumor promotion, was detected after treatment with all OH-PCBs under study, with the persistent OH-PCBs being the strongest ones. Several compounds were found to significantly induce the AhR-mediated activity, including 4'-OH-PCB 79, a metabolite of PCB 77, and 2-(4'-chloro)- and 2-(3',4'-dichloro)-1,4-benzoquinones and 1,4-hydroquinones. Low molecular weight OH-PCBs, such as 3'-hydroxy, 4'-, and 3',4'-dihydroxy-4-chlorobiphenyl, elicited significant estrogenic activity and potentiated effect of 17beta-estradiol. Antiestrogenic potencies, determined in the presence of 17beta-estradiol, were found for persistent 4-OH-PCB 187, 4-OH-PCB 146, and some low chlorinated PCB derivatives. However, no apparent association between induction of AhR activity and antiestrogenicity was observed. The majority of the OH-PCBs suppressed the 17beta-estradiol response only at cytotoxic concentrations. Spearman's rank correlations were calculated for these biological data and the physicochemical descriptors, hydrophobicity (log P), molar volume, pKa, log D, and dihedral angle. Significant correlations were found between potency to downregulate GJIC and log P and molar volume (R = -0.7, p < 0.0001). Antiestrogenic effects were also negatively correlated with hydrophobicity and molar volume. No significant correlations among other biological end points and the physicochemical descriptors were observed for the entire set of compounds. These results show that oxygenated PCB metabolites are capable of multiple adverse effects, including gap junction inhibition, AhR-mediated activity, and (anti)estrogenicity. The inhibition of GJIC by OH-PCBs represents a novel mode of action of both the lower chlorinated and the persisting high molecular weight OH-PCBs.},

note = {Place: United States},

keywords = {Adenocarcinoma/metabolism/pathology, Animals, Aryl Hydrocarbon/*biosynthesis, Breast Neoplasms/metabolism/pathology, Carcinoma, Cell Line, Cell Survival/drug effects, Dose-Response Relationship, Down-Regulation, Drug, Environmental Pollutants/*toxicity, Epithelial Cells/drug effects/metabolism, Estrogen/*biosynthesis, Gap Junctions/*drug effects/metabolism, Hepatocellular/metabolism/pathology, Humans, Hydroquinones, Hydroxylation, Liver Neoplasms/metabolism/pathology, Neoplasms/*metabolism/pathology, Polychlorinated Biphenyls/*toxicity, Quinones/*toxicity, Rats, Receptors, Tumor},

pubstate = {published},

tppubtype = {article}

}

@article{pachernik_multiple_2002,

title = {Multiple biological effects of inhibitors of arachidonic acid metabolism on human keratinocytes.},

author = {Jirí Pacherník and Ales Hampl and Karel Soucek and Martina Kovaríková and Zdenek Andrysík and Jirina Hofmanová and Alois Kozubík},

doi = {10.1007/s00403-001-0288-5},

issn = {0340-3696},

year  = {2002},

date = {2002-02-01},

journal = {Archives of dermatological research},

volume = {293},

number = {12},

pages = {626–633},

abstract = {BACKGROUND: Various compounds that inhibit processing of arachidonic acid (AA) are being intensively tested for their antitumour activity. However, the mechanisms responsible for such activity remain rather elusive. To approach this issue, we examined the effects of several structurally different inhibitors of AA metabolism in the human keratinocyte HaCaT cell line. METHODS: Several parameters were determined in HaCaT cells exposed to increasing concentrations of the inhibitors for 24 and/or 48 h. These included (1) oxidoreductase activity, total protein mass and cell cycle distribution to assess cell proliferation, (2) degradation of PARP protein to assess apoptosis, and (3) cell morphology, distribution of F-actin and expression of cytokeratins and E-cadherin to evaluate changes in differentiation status. RESULTS: While eicosatetraynoic acid (ETYA), nordihydroguaiaretic acid (NDGA), esculetin and MK-886 reduced proliferation of HaCaT cells, the cyclooxygenase inhibitors indomethacin and piroxicam had no such effects. Esculetin and NDGA arrested cells in S phase, and ETYA and MK-886 delayed cell progression through G(1) phase. Higher concentrations of NDGA, MK886 and/or ETYA caused cleavage of PARP. No changes in the expression of cytokeratins and E-cadherin were observed upon treatment with any of the inhibitors. However, esculetin induced redistribution of F-actin accompanied by increased cell adhesion and size. CONCLUSION: Our findings indicate that, in addition to their ability to inhibit cell proliferation and to induce apoptosis, lipoxygenase inhibitors and/or ETYA may also elicit other important physiological responses in HaCaT keratinocytes.},

note = {Place: Germany},

keywords = {11, 14-Eicosatetraynoic Acid/pharmacology, 5, 8, Arachidonic Acid/*antagonists & inhibitors, Cell Differentiation/drug effects, Cell Division/drug effects, Cell Line, Cell Survival/drug effects, Cyclooxygenase Inhibitors/pharmacology, Humans, Indoles/pharmacology, Keratinocytes/cytology/*drug effects/*physiology, Lipoxygenase Inhibitors/pharmacology, Transformed, Umbelliferones/pharmacology},

pubstate = {published},

tppubtype = {article}

}