Latest Publications

@article{vondalova_blanarova_cisplatin_2011,

title = {Cisplatin and a potent platinum(IV) complex-mediated enhancement of TRAIL-induced cancer cells killing is associated with modulation of upstream events in the extrinsic apoptotic pathway.},

author = {Olga Vondálová Blanárová and Iva Jelínková and Arpád Szöor and Belma Skender and Karel Soucek and Viktor Horváth and Alena Vaculová and Ladislav Andera and Petr Sova and János Szöllosi and Jirina Hofmanová and György Vereb and Alois Kozubík},

doi = {10.1093/carcin/bgq220},

issn = {1460-2180 0143-3334},

year  = {2011},

date = {2011-01-01},

journal = {Carcinogenesis},

volume = {32},

number = {1},

pages = {42–51},

abstract = {TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) can selectively trigger apoptosis in various cancer cell types. However, many cancer cells are resistant to death receptor-mediated apoptosis. Combination therapy with platinum complexes may affect TRAIL-induced signaling via modulation of various steps in apoptotic pathways. Here, we show that cisplatin or a more potent platinum(IV) complex LA-12 used in 20-fold lower concentration enhanced killing effects of TRAIL in human colon and prostate cancer cell lines via stimulation of caspase activity and overall apoptosis. Both platinum complexes increased DR5 surface expression in colon cancer cells. Small interfering RNA-mediated DR5 silencing rescued cells from sensitizing effects of platinum drugs on TRAIL-induced caspase-8 activation and apoptosis, showing the functional importance of DR5 in the effects observed. In addition, both cisplatin and LA-12 triggered the relocalization of DR4 and DR5 receptors to lipid rafts and accelerated internalization of TRAIL, which may also affect TRAIL signaling. Collectively, modulations of the initial steps of the extrinsic apoptotic pathway at the level of DR5 and plasma membrane are important for sensitization of colon and prostate cancer cells to TRAIL-induced apoptosis mediated by LA-12 and cisplatin.},

note = {Place: England},

keywords = {Amantadine/*analogs & derivatives/pharmacology, Apoptosis/*drug effects/physiology, Blotting, Cell Line, Cell Separation, Cisplatin/*pharmacology, Confocal, Flow Cytometry, Fluorescent Antibody Technique, Humans, Microscopy, Neoplasms/*metabolism, Organoplatinum Compounds/*pharmacology, Protein Transport/drug effects, Receptors, Reverse Transcriptase Polymerase Chain Reaction, RNA Interference, Signal Transduction/*drug effects/physiology, TNF-Related Apoptosis-Inducing Ligand/*metabolism, TNF-Related Apoptosis-Inducing Ligand/metabolism, Tumor, Western},

pubstate = {published},

tppubtype = {article}

}

@article{svihalkova-sindlerova_-12_2010,

title = {LA-12 overcomes confluence-dependent resistance of HT-29 colon cancer cells to Pt (II) compounds.},

author = {Lenka Svihálková-Sindlerová and Vendula Foltinová and Alena Vaculová and Viktor Horváth and Karel Soucek and Petr Sova and Jirina Hofmanová and Alois Kozubík},

issn = {1791-7530 0250-7005},

year  = {2010},

date = {2010-04-01},

journal = {Anticancer research},

volume = {30},

number = {4},

pages = {1183–1188},

abstract = {BACKGROUND: LA-12 is a new platinum (IV) drug with promising cytotoxic effects in a wide range of cancer cell lines. Its confluence-dependent effects were compared with cisplatin (CDDP) and oxaliplatin (L-OHP) in HT-29 cells. MATERIALS AND METHODS: Cytotoxicity was determined by MTT test, eosin exclusion assay, and cell number quantification. The cell cycle was analysed using propidium iodide DNA staining (flow cytometry), apoptosis by phosphatidylserine externalisation (annexin-V assay), mitochondrial membrane potential by flow cytometry, nuclear morphology by means of fluorescence microscopy, and PARP cleavage by Western blotting. RESULTS: While L-OHP and CDDP were practically inactive in the subconfluent cell population, LA-12 showed a similar toxicity in both subconfluent and growing populations. All compounds induced apoptosis, although with different potentials. CONCLUSION: LA-12 was able to overcome confluence-dependent resistance of HT-29 cells observed for other platinum compounds, which may have potential therapeutic use in slowly growing tumours.},

note = {Place: Greece},

keywords = {Adenocarcinoma/*drug therapy, Amantadine/*analogs & derivatives/pharmacology, Antineoplastic Agents/*pharmacology, Apoptosis/drug effects, Cell Adhesion/drug effects, Cisplatin/pharmacology, Colonic Neoplasms/*drug therapy/pathology, Dose-Response Relationship, Drug, Drug resistance, HT29 Cells, Humans, Neoplasm, Organoplatinum Compounds/*pharmacology, Oxaliplatin},

pubstate = {published},

tppubtype = {article}

}

@article{horvath_different_2007,

title = {Different cell cycle modulation following treatment of human ovarian carcinoma cells with a new platinum(IV) complex vs cisplatin.},

author = {Viktor Horváth and Karel Soucek and Lenka Svihálková-Sindlerová and Jan Vondrácek and Olga Blanárová and Jirina Hofmanová and Petr Sova and Alois Kozubík},

doi = {10.1007/s10637-007-9062-7},

issn = {0167-6997},

year  = {2007},

date = {2007-10-01},

journal = {Investigational new drugs},

volume = {25},

number = {5},

pages = {435–443},

abstract = {Platinum (IV) derivative with adamantylamine-LA-12-represents a new generation of highly efficient anti-cancer drug derived from cisplatin and is currently in the final stage of phase I clinical trials. Understanding the specific mechanisms of its effects on cell cycle is necessary for defining the mode of action of LA-12. In this study, we characterized the ability of LA-12 to induce cell cycle perturbations in ovarian cancer cell line A2780 as compared to equitoxic cisplatin treatment. LA-12 induced a permanent accumulation of A2780 cells in S phase while cisplatin caused G2/M arrest at 24-h time point, where we also detected an increased expression of Gadd45alpha protein. Although both derivatives induced a rapid increase of p53 expression, this was not associated with a down-regulation of Mdm2 protein. Increased expression of p21(Cip1/WAF1) protein and its association with cyclins A and B1 suggested that this cyclin-dependent kinase inhibitor might contribute significantly to the observed perturbations of cell cycle. The results of this study provide insight into the mechanism of action of platinum-based derivative with adamantylamine on cell cycle in ovarian cancer cells. The differences between effects of LA-12 and cisplatin suggest that more attention should be paid to elucidation of modes of action of novel platinum(IV) complexes at cellular level.},

note = {Place: United States},

keywords = {Amantadine/*analogs & derivatives/pharmacology, Antineoplastic Agents/*pharmacology, bcl-2-Associated X Protein/metabolism, Carcinoma/drug therapy/metabolism, Cell Cycle Proteins/metabolism, Cell Cycle/*drug effects, Cell Line, Cell Proliferation/drug effects, Cisplatin/*pharmacology, Female, Humans, Organoplatinum Compounds/*pharmacology, Ovarian Neoplasms/drug therapy/metabolism, Proto-Oncogene Proteins c-mdm2/metabolism, Tumor, Tumor Suppressor Protein p53/metabolism},

pubstate = {published},

tppubtype = {article}

}

@article{kozubik_high_2005,

title = {High effectiveness of platinum(IV) complex with adamantylamine in overcoming resistance to cisplatin and suppressing proliferation of ovarian cancer cells in vitro.},

author = {Alois Kozubík and Viktor Horváth and Lenka Svihálková-Sindlerová and Karel Soucek and Jirina Hofmanová and Petr Sova and Ales Kroutil and Frantisek Zák and Adolf Mistr and Jaroslav Turánek},

doi = {10.1016/j.bcp.2004.09.005},

issn = {0006-2952},

year  = {2005},

date = {2005-02-01},

journal = {Biochemical pharmacology},

volume = {69},

number = {3},

pages = {373–383},

abstract = {[(OC-6-43)-bis(acetato)(1-adamantylamine)amminedichloroplatinum(IV)], coded as LA-12, is an octahedral platinum(IV) complex containing a bulky hydrophobic ligand - adamantylamine. The use of bulky hydrophobic amines as non-leaving ligands, may increase uptake of the compound by the cancer cells. Therefore, the effects of LA-12 on sensitive (A2780) and cisplatin resistant (A2780cis) ovarian cancer cell lines were investigated and compared to those of cisplatin. IC(50) and IC(90) concentrations of LA-12 were 6- (A2780) or 18-fold (A2780cis) lower than those for cisplatin (MTT assay). Equitoxic concentrations (IC(50) or IC(90)) of both compounds caused a significant and similar time- and dose-dependent inhibition of cell proliferation and an increase in the number of floating cells which corresponded to the decrease of total cell viability. A different type and dynamics of cell cycle perturbation after cisplatin and LA-12 treatment were detected. Exposure to LA-12 resulted in transient accumulation of A2780 and A2780cis cells in S phase, while cisplatin caused G(2)/M arrest in sensitive and S phase arrest in resistant cells. A relatively low rate of apoptosis after exposure to IC(50) or IC(90) of both complexes was observed, markedly higher in resistant A2780cis cells. Western blot analysis indicated a concentration-dependent p53 level increase in both lines (higher after cisplatin treatment). PARP cleavage was observed only in A2780cis cells. In conclusion, LA-12 was found to be significantly more efficient than cisplatin, and it was able to overcome the acquired cisplatin resistance (showing resistance factor 2.84-fold lower than those for cisplatin). In spite of the low rate of apoptosis, LA-12 caused increase of p53 level and cell cycle perturbations in the ovarian cancer cell lines studied.},

note = {Place: England},

keywords = {Amantadine/*analogs & derivatives/*pharmacology, Antineoplastic Agents/*pharmacology, Cell Cycle/drug effects, Cell Line, Cell Proliferation/drug effects, Cisplatin/*pharmacology, DNA Fragmentation/drug effects, Drug resistance, Female, Humans, Neoplasm, Organoplatinum Compounds/*pharmacology, Ovarian Neoplasms/*drug therapy/pathology, Poly(ADP-ribose) Polymerases/analysis, Tumor, Tumor Suppressor Protein p53/analysis},

pubstate = {published},

tppubtype = {article}

}