Volume 40, No. 8/2002(August)
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 Int. Journal of Clinical Pharmacology and Therapeutics
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Preface
Cellular resistance as a function within the kinetic network of survival and apoptosis factors
F. Gieseler and V. Nüssler
Abstract
F. Gieseler and V. Nüssler
Introduction
Cellular resistance as a function within the kinetic network of survival and apoptosis factors
H. Grunicke
Original
Thrombin as a survival factor for cancer cells: thrombin activation in malignant effusions in vivo and inhibition of idarubicin-induced cell death in vitro
H. Schiller, T. Bartscht, A. Arlt, M.O. Zahn, A. Seifert, T. Bruhn, H.D. Bruhn and F. Gieseler
Abstract
H. Schiller1, T. Bartscht1, A. Arlt1, M.O. Zahn1, A. Seifert1, T. Bruhn2, H.D. Bruhn1 and F. Gieseler1
1Department of Internal Medicine, Section Hematology and Oncology, and 2Department of Toxicology, University Hospital of Kiel, Kiel, Germany
Objectives: The aim of the experiments shown here, is to demonstrate exemplarily that thrombin can be a survival factor for malignant cells. Methods: Activation of the coagulation system has been examined in patients with acute myeloid leukemia (AML) and non-Hodgkin lymphoma (NHL) before and after chemotherapy as well as in malignant effusions of heavily pretreated patients with solid tumors. Thrombin receptor expression (PAR-1) has been examined on HL-60 cells; the effect of thrombin on the proliferation of the cells and inhibition of apoptosis induction by idarubicin has been shown. Results: Using fibrinopeptide A as an indirect parameter for thrombin activation, we found elevated levels in patients with AML and NHL before and a significant 2-fold increase after chemotherapy (p < 0.02 for the AML group; p < 0.0006 for the NHL group). Apparently, this does not only affect patients with hematological diseases, but also with solid tumors. In order to find out if the tumor cells directly activate thrombin, we examined malignant effusions of patients with different solid tumors. Comparing prothrombin fragment 1 + 2 in ascites and pleural effusions with the patients’ serum levels, we found it significantly increased in all cases (mean of 1.96 ± 0.5 nmol/l in the serum vs. 12.1 ± 3.6 nmol/l in effusions; p < 0.001). The majority of patients presented elevated serum levels. Additionally, we incubated HL-60 cells (human promyelocytic leukemia) with thrombin prior to treatment with idarubicin. Expression of thrombin receptor (PAR-1) could be verified by FACS-analysis using a monoclonal antibody. HL-60 cells responded with increased proliferation to thrombin exposure with concentrations between 0.3 and 3 U/ml. This effect could be abolished by the addition of hirudin, demonstrating thrombin specificity. In these concentrations, thrombin was able to abrogate the induction of apoptosis by idarubicin completely (p < 0.005). Conclusions: Here we give evidence for the role of thrombin as a resistance factor for tumor cells towards chemotherapy. In the light of the fact that thrombin is regularly activated in cancer patients, these findings indicate that thrombin is a clinically relevant cellular resistance factor. A number of pre-clinical and clinical studies imply that inhibition of the coagulation system, e.g. by low-molecular weight heparins or warfarin, increases the effect of chemotherapy.Correspondence to:
Dr. F. Gieseler; University Hospital of Kiel, Department of Internal Medicine, Section Hematology and Oncology, Schittenhelmstraße 12, D-24105 Kiel, Germany
Email: gieseler@email.uni-kiel.de
Review
NFkB-dependent chemoresistance in solid tumors
A. Arlt and H. Schäfer
Abstract
A. Arlt and H. Schäfer
Laboratory of Molecular Gastroenterology, First Department of Medicine, University of Kiel, Germany
Abstract. The Rel/NFkB family of transcription factors is involved in multiple cellular processes, including inflammation, cell cycle regulation, apoptosis and oncogenesis. Constitutive activation of NFkB has been described in a great number of solid tumors and this activation appears to support cancer cell survival and to reduce the sensitivity against chemotherapeutic drugs. Additionally, some of these drugs induce this transcription factor themselves and through this mechanism lower their cytotoxic potential. Inhibition of NFkB by various means has been shown to enhance the sensitivity to antineoplastic- or radiation-induced apoptosis in vitro and in vivo. Furthermore, suppression of NFkB results in attenuation of cancer cachexia and metastasis in some mouse tumor models. Studies are underway to further delineate the role of NFkB in cancer cell survival, growth and resistance to standard chemotherapy and radiation regimens. Moreover, the effects of novel therapeutic agents which specifically target NFkB proteins are currently being assessed in experimental models of cancer cell growth both in vitro and in vivo. In this review, we discuss the possible involvement of NFkB in the chemoresistance of various solid tumors and potential future treatment strategies based on NFkB inhibition.Correspondence to:
Dr. H. Schäfer; Laboratory of Molecular Gastroenterology, First Department of Medicine, University of Kiel, Schittenhelmstraße 12, D-24105 Kiel, Germany
Email: hschaef@1med.uni-kiel.de
Original
4-1BB ligand – just another costimulating molecule?
H.R. Salih, P.A. Kiener and V. Nüssler
Abstract
H.R. Salih1, P.A. Kiener2 and V. Nüssler3
1Department of Internal Medicine II, University Hospital of the Eberhard Karls University, Tübingen, 2MedImmune Inc., Gaithersburg, MD, USA, and 3Department of Internal Medicine III, University Hospital Großhadern, München, Germany
Initially, scientific interest in the 4-1BB/4-1BB Ligand system focused on the role of the 4-1BB (CD137) receptor in the costimulation of T cells. More recently, evidence is accumulating that 4-1BBL is more than “just” the ligand for a costimulatory molecule. In this review we discuss the functional properties of 4-1BB Ligand such as its preference for CD8 positive T cells and the differences to costimulation via the B7/CD28 system. Furthermore, the available data regarding its ability to transduce signals bidirectionally, i.e. also back into the ligand bearing cell, its release as a soluble form following shedding from the cell surface, and its role in the interaction of tumor cells with the immune system are reviewed.Correspondence to:
Dr. H. R. Salih; Department of Internal Medicine II, University Hospital, Eberhard Karls University, Ottfried-Müller-Straße 10, D-72076 Tübingen, Germany
Email: Helmut.Salih@med.uni-tuebingen.de
Review
DNA repair in resistance to alkylating anticancer drugs
B. Kaina and M. Christmann
Abstract
B. Kaina and M. Christmann
Institute of Toxicology, Division of Applied Toxicology, University of Mainz, Mainz, Germany
The major critical target of alkylating antineoplastic drugs belonging to the group of methylating and chloroethylating agents is DNA. DNA alkylation lesions can be repaired by the action of alkyltransferase (MGMT) and base excision repair enzymes. The major cell killing and apoptotic alkylation lesions are O6-methylguanine (O6MeG) and O6-chloroethylguanine. O6MeG causes mispairing with thymine which is erroneously processed by mismatch repair (MMR), leading to secondary lesions that potently trigger the mitochondrial apoptotic pathway. Apoptosis induced by O6MeG is a late cellular response that requires cell proliferation to occur. Data are available indicating that DNA double-strand breaks are actively involved as the ultimate trigger of apoptosis. O6MeG and O6-chloroethylguanine are repaired by the specific action of MGMT thus counteracting the killing effects of the lesions. The expression of MGMT is highly variable and is often increased in tumors compared to normal tissue. Determination of MGMT activity in various tumors showed low expression in brain, pancreas and skin and high expression in testicle, breast, colorectal, lung and ovarian tumors. Distribution profiles of MGMT revealed non-random distribution indicating the existence of subpopulations exhibiting low and high activity. Since MGMT is one of the most important factors determining drug resistance to alkylation, strategies have been developed to inhibit MGMT in tumors with the aid of MGMT inhibitors and overexpression of MGMT in healthy, non-target tissue (e.g. blood stem cells) by transferring a mutated form of MGMT inaccessible to inhibition. Targeting MGMT inhibitors to tumors may further enhance the antineoplastic efficiency of alkylating agents. The role of base excision repair, Fos and p53 in drug resistance to alkylation is also discussed.Correspondence to:
Dr. B. Kaina; Institute of Toxicology, Division of Applied Toxicology, University of Mainz, Obere Zahlbacher Straße 67, D-55131 Mainz, Germany
Email: Kaina@mail.uni-mainz.de
Original
Cytoprotective features of selenazofurin in hematopoietic cells
A. Pogrebniak, M. Hasmann, I. Schemainda, R. Pelka-Fleischer and V. Nuessler
Abstract
A. Pogrebniak1, M. Hasmann2,3, I. Schemainda2, R. Pelka-Fleischer1 and V. Nuessler1
1Medizinische Klinik III, Forschungslabor A, Klinikum Großhadern, 2Klinge Pharma GmbH, Munich and 3Roche Diagnostics GmbH, Pharma Research Penzberg, Germany
Objectives: Antineoplastic activity of tiazofurin (Tz) and selenazofurin (Se) depends on their conversion to substances which are analogs of NAD. NAD performs pleiotropic and essential cellular functions, both as a cofactor in oxidation-reduction reactions and as a substrate for poly- and mono-ADP-ribosylation reactions. The therapeutic potential of modulating intracellular NAD levels and activity of NAD-dependent enzymes by concomitant administration of conventional anticancer agents merits further research. Our aim was to investigate the cytotoxic effects of Tz and Se in hematopoietic cells and to test their ability to potentiate the effects of DNA strand-disrupting agents. Material: THP-1, a cell line, derived from human acute monoblastic leukemia, was used. CLL lymphocytes were obtained from 8 patients with CLL. Methods: The WST-1 test was used to detect the function of NAD(P)-dependent dehydrogenases after exposure of THP-1 cells to Tz or Se. Cytotoxicity of Tz, Se, MNNG and chlorambucil was assessed using the membrane permeability assay (PI test). Results: THP-1 cells were sensitive to cytotoxic effects of Tz and Se, with IC50 values of 2.5 × 10–5 M for Tz and 2 × 10–6 M for Se, as determined with the WST-1 test; 10 mM Se induced cell membrane disruption in more than 20% of THP-1 cells 48 hours after commencement of treatment, whereas the same concentration of Tz failed to increase membrane permeability. Pretreatment of THP-1 cells with 0.5 – 1.5 mM Se had no effect on the time course of cell death, induced by treatment with the DNA-damaging agent 1-methyl-3-nitro-1- nitrosoguanidinium (MNNG) for 36 hours. However, when incubation of THP-1 cells with MNNG was prolonged (72 hours) without changing the incubation medium, pretreatment with Se had the following effects: the relative number of cells that died spontaneously decreased, and the cytotoxicity of MNNG was diminished. This effect was also demonstrated ex vivo in 6 of 8 cases of CLL, treated with MNNG and chlorambucil. Conclusions: Contrary to other investigations, we here demonstrate that preincubation with Se may partially protect cells from cell death induced by the alkylating agents MNNG and chlorambucil in the THP-1 cell line and in CLL lymphocytes presumably by affecting spontaneous cell death.Correspondence to:
Dr. V. Nuessler; Klinikum Großhadern, Medizinische Klinik III, Forschungslabor A5E00327, Marchioninistraße 15, D-81377 Munich, Germany
Email: nuessler@gmx.net.
Original
New insights into the clinical pharmacokinetics of trofosfamide
A. Brinker, J. Kisro, C. Letsch, S.K. Brüggemann and T. Wagner
Abstract
A. Brinker, J. Kisro, C. Letsch, S.K. Brüggemann and T. Wagner
Department of Hematology/Oncology, Medical University of Lübeck, Germany
Objective: This study focuses on the pharmacokinetics of trofosfamide (TRO) and metabolites after oral administration of TRO. Methods: Twelve patients with solid tumors and non-Hodgkin lymphomas were treated with 450 mg TRO orally for 7 days. TRO and the stable metabolites ifosfamide (IFO), cyclophosphamide (CYC), 2- and 3-dechloroethylifosfamide (2-DCE, 3-DCE) were determined by GC and the sum of the 4-OH-metabolites was measured by HPLC. Results: A fast metabolism of TRO with a half-life of about 1 h was observed. IFO was the main stable metabolite, whereas CYC was only detected in minor quantities. The peak levels and the AUC of the 4-OH-metabolites were 9.5 and 4.3 times higher than observed after an equimolar IFO dose. Only 6% of the administered dose was recovered in urine within 24 hours as stable metabolites. TRO was under limit of detection. Conclusions: Our results confirm that dechloroethylation of TRO to IFO is a major metabolic pathway. Additionally, we found considerable 4-hydroxylation not shown previously. With respect to the low levels of IFO and CYC observed, the sum of 4-OH-metabolites cannot be explained by hydroxylation of these metabolites only. Hence, we assume a direct 4-hydroxylation of TRO occurring to a high extent. Bioavailability of TRO could not be calculated directly, because TRO is only available as an oral formulation. The bioavailability of oral IFO, however, is reported to be almost 100%. Therefore, after normalization of the dose, a bioavailability of 32% for IFO after oral TRO could be calculated. Thus, in contrast to previous reports, direct 4-hydroxylation of TRO seems to be the main metabolic pathway.Correspondence to:
Dr. T. Wagner; Department of Hematology/Oncology, Medical University of Lübeck, Ratzeburger Allee 160, D-23538 Lübeck, Germany
Email: wagnerth@medinf.mu-luebeck.de
Extended Abstract
Effect and interaction of 7-hydroxy methotrexate and methotrexate in AML and ALL patient samples: measured by the thymidylate synthase inhibition assay
R.M. Lingg, M.G. Rots, C.H. Van Zantwijk, G. Hempel, G.J.L. Kaspers and J. Boos
Abstract
R.M. Lingg1, M.G. Rots2, C.H. Van Zantwijk2, G. Hempel1, G.J.L. Kaspers2 and J. Boos1
Extended Abstract
Population pharmacokinetics of oral busulfan in children
B. Schiltmeyer, G. Hempel, M. Schwab, C. Ritter, T. Klingebiel and J. Boos
Abstract
B. Schiltmeyer1,2, G. Hempel1,2, M. Schwab3, C. Ritter3, T. Klingebiel4 and J. Boos2
Extended Abstract
Clinical and pharmacokinetic study with liposomal doxorubicin (DL-1) in patients with advanced metastatic cancer – results from a phase-I study
K. Mross, T. Gierlich, B. Häring, W. März and C. Unger
Abstract
K. Mross, T. Gierlich, B. Häring, W. März and C. Unger
Abstracts
Cellular drug-resistance within the kinetic network of survival and apoptosis factors
Cooperative Study Group Cellular Resistance th Interdisciplinary Workshop, Kiel, Germany
Abstract
Cooperative Study Group Cellular Resistance 10th Interdisciplinary Workshop, Kiel, Germany
