Latest Publications

@article{chramostova_polycyclic_2004,

title = {Polycyclic aromatic hydrocarbons modulate cell proliferation in rat hepatic epithelial stem-like WB-F344 cells.},

author = {Katerina Chramostová and Jan Vondrácek and Lenka Sindlerová and Borivoj Vojtesek and Alois Kozubík and Miroslav Machala},

doi = {10.1016/j.taap.2003.12.008},

issn = {0041-008X},

year  = {2004},

date = {2004-04-01},

journal = {Toxicology and applied pharmacology},

volume = {196},

number = {1},

pages = {136–148},

abstract = {Although many polycyclic aromatic hydrocarbons (PAHs) are recognized as potent mutagens and carcinogens, relatively little is known about their role in the tumor promotion. It is known that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can induce release of rat hepatic oval epithelial cells from contact inhibition by a mechanism possibly involving the aryl hydrocarbon receptor (AhR) activation. Many PAHs are AhR ligands and are known to act as transient inducers of AhR-mediated activity. In this study, effects of 19 selected PAHs on proliferation of confluent rat liver epithelial WB-F344 cells were investigated. Non-mutagens that are weak activators or nonactivators of AhR-mediated activity had no effect on cell proliferation. Relatively strong or moderate AhR ligands with low mutagenic potencies, such as benzofluoranthenes, benz[a]anthracene, and chrysene, were found to increase cell numbers, which corresponded to an increased percentage of cells entering S-phase. Strong mutagens, including benzo[a]pyrene and dibenzo[a,l]pyrene, increased a percentage of cells in S-phase without inducing a concomitant increase in cell numbers. The treatment with mutagenic PAHs was associated with an increased DNA synthesis and induction of cell death, which corresponded with the activation of p53 tumor suppressor. Apoptosis was blocked by pifithrin-alpha, the chemical inhibitor of p53. Both weakly and strongly mutagenic PAHs known as AhR ligands were found to induce significant increase of cytochrome P4501A activity, suggesting a presence of functional AhR. The results of the present study seem to suggest that a release from contact inhibition could be a part of tumor promoting effects of AhR-activating PAHs; however, the genotoxic effects of some PAHs associated with p53 activation might interfere with this process.},

note = {Place: United States},

keywords = {Animals, Apoptosis/drug effects, Aryl Hydrocarbon/metabolism, Cell Division/drug effects, Cells, Cultured, Cytochrome P-450 CYP1A1/metabolism, Dose-Response Relationship, Drug, Epithelial Cells/*drug effects/enzymology/metabolism, Liver/*cytology, Mutagens/*toxicity, Polycyclic Aromatic Hydrocarbons/*toxicity, Rats, Receptors, Stem Cells/*drug effects/enzymology/metabolism, Tumor Suppressor Protein p53/biosynthesis},

pubstate = {published},

tppubtype = {article}

}

@article{kovarikova_effects_2004,

title = {The effects of TNF-alpha and inhibitors of arachidonic acid metabolism on human colon HT-29 cells depend on differentiation status.},

author = {Martina Kovaríková and Jirina Hofmanová and Karel Soucek and Alois Kozubík},

doi = {10.1111/j.1432-0436.2004.07201006.x},

issn = {0301-4681},

year  = {2004},

date = {2004-02-01},

journal = {Differentiation; research in biological diversity},

volume = {72},

number = {1},

pages = {23–31},

abstract = {The level of differentiation could influence sensitivity of colonic epithelial cells to various stimuli. In our study, the effects of TNF-alpha, inhibitors of arachidonic acid (AA) metabolism (baicalein, BA; indomethacin, INDO; niflumic acid, NA; nordihydroguaiaretic acid, NDGA), and/or their combinations on undifferentiated or sodium butyrate (NaBt)-differentiated human colon adenocarcinoma HT-29 cells were compared. NaBt-treated cells became growth arrested (blocked in G0/G1 phase of the cell cycle), and showed down-regulated Bcl-xL and up-regulated Bak proteins and increased expression of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX). These cells were more perceptive to anti-proliferative and apoptotic effects of TNF-alpha. Both inhibitors of LOX (BA and NDGA) and COX (INDO and NA) in higher concentrations modulated cell cycle changes accompanying NaBt-induced differentiation and induced various level of cell death in undifferentiated and differentiated cells. Most important is our finding that TNF-alpha action on proliferation and cell death can be potentiated by co-treatment of cells with AA metabolism inhibitors, and that these effects were more significant in undifferentiated cells. TNF-alpha and INDO co-treatment was associated with accumulation of cells in G0/G1 cell cycle phase, increased reactive oxygen species production, and elevated caspase-3 activity. These results indicate the role of differentiation status in the sensitivity of HT-29 cells to the anti-proliferative and proapoptotic effects of TNF-alpha, AA metabolism inhibitors, and their combinations, and imply promising possibility for novel anti-cancer strategies.},

note = {Place: England},

keywords = {*Flavanones, Adenocarcinoma/drug therapy/pathology, Arachidonate 5-Lipoxygenase/metabolism, Arachidonic Acid/*metabolism, Butyrates/pharmacology, Caspase 3, Caspases/drug effects/metabolism, Cell Cycle/drug effects, Cell Differentiation/*drug effects, Cell Division/drug effects, Colonic Neoplasms/drug therapy/metabolism/pathology, Cyclooxygenase 2, Cyclooxygenase 2 Inhibitors, Cyclooxygenase Inhibitors/*pharmacology, Drug Synergism, Flavonoids/pharmacology, HT29 Cells/drug effects, Humans, Indomethacin/pharmacology, Isoenzymes/antagonists & inhibitors/metabolism, Lipoxygenase Inhibitors/*pharmacology, Masoprocol/pharmacology, Membrane Proteins, Niflumic Acid/pharmacology, Prostaglandin-Endoperoxide Synthases/metabolism, Tumor Necrosis Factor-alpha/*pharmacology},

pubstate = {published},

tppubtype = {article}

}

@article{vaculova_tumor_2002,

title = {Tumor necrosis factor-alpha induces apoptosis associated with poly(ADP-ribose) polymerase cleavage in HT-29 colon cancer cells.},

author = {Alena Vaculová and Jirina Hofmanova and Karel Soucek and Martina Kovariková and Alois Kozubík},

issn = {0250-7005},

year  = {2002},

date = {2002-06-01},

journal = {Anticancer research},

volume = {22},

number = {3},

pages = {1635–1639},

abstract = {BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha) is known for its selective cytotoxic activity on tumour cells. We analysed the response of HT-29 human colon carcinoma cells to this cytokine. MATERIALS AND METHODS: After TNF-alpha treatment, cell proliferation, cell cycle, reactive oxygen species (ROS) production (flow cytometry), the amount of apoptotic cells (flow cytometry, fluorescence microscopy), cleavage of poly (ADP-ribose) polymerase (PARP) and caspase-3 activity (Western blotting) were detected. RESULTS: TNF-alpha induced a decrease of cell growth and viability, an accumulation of cells in the S-phase of the cell cycle, an increase of subdiploid cell population and nuclear chromatin condensation and fragmentation, but not sooner than 96-120 hours. However, earlier events characteristic of apoptosis occurred, such as caspase-3 activation, PARP cleavage to 89 kDa fragment and changes in ROS production. CONCLUSION: We demonstrated that, in addition to being an early marker of apoptosis, activation of caspase-3 and degradation of PARP may play a causative role in HT-29 cell death induced by TNF-alpha.},

note = {Place: Greece},

keywords = {Apoptosis/*drug effects, Caspase 3, Caspases/metabolism, Cell Death/drug effects, Cell Division/drug effects, HT29 Cells/*drug effects/enzymology/pathology, Humans, Kinetics, Poly(ADP-ribose) Polymerases/*metabolism, Reactive Oxygen Species/metabolism, Tumor Necrosis Factor-alpha/*pharmacology},

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}

}

@article{hoferova_effect_2002,

title = {The effect of nonsteroidal antiinflammatory drugs ibuprofen, flurbiprofen, and diclofenac on in vitro and in vivo growth of mouse fibrosarcoma.},

author = {Zuzana Hoferová and Peter Fedorocko and Jirina Hofmanová and Michal Hofer and Vladimír Znojil and Katerina Minksová and Karel Soucek and Alena Egyed and Alois Kozubík},

doi = {10.1081/cnv-120002149},

issn = {0735-7907},

year  = {2002},

date = {2002-01-01},

journal = {Cancer investigation},

volume = {20},

number = {4},

pages = {490–498},

abstract = {For suppression of primary G:5:113 fibrosarcoma growth, three structurally different cyclooxygenase (COX) inhibitors (ibuprofen, flurbiprofen, and diclofenac) were administered intraperitoneally (i.p.) in two regimens starting on day 5 after tumor-cell inoculation. Repeated application of 0.15 mg/mouse/day during 14 consecutive days significantly suppressed the tumor growth and increased the percentage of surviving mice. Similar tendency, however without significant differences, was observed when animals were given 0.5 mg/day for five consecutive days. These results suggest that a time schedule of drug application is important for the therapeutic effect. Suppressive effect of diclofenac and flurbiprofen on tumor growth was also observed under in vitro conditions. We conclude that suppressive effect of these drugs on tumor growth in vivo comprises both direct effects of COX inhibitors on fibrosarcoma cells and indirect effects that are presumably mediated by extratumoral sources. Our findings encourage the use of COX inhibitors in the therapy of fibrosarcoma.},

note = {Place: England},

keywords = {Animals, Anti-Inflammatory Agents, Cell Cycle/drug effects, Cell Division/drug effects, Cultured/*drug effects, Diclofenac/*therapeutic use, Experimental, Fibrosarcoma/*drug therapy/pathology, Flurbiprofen/*therapeutic use, Ibuprofen/*therapeutic use, In Vitro Techniques, Inbred C3H, Male, Mice, Neoplasms, Non-Steroidal/*therapeutic use, Survival Rate, Tumor Cells},

pubstate = {published},

tppubtype = {article}

}