Biomedical subjects

Claus Belka

Publications and source records attributed to Claus Belka.

At least 19 recordsLinked to original sources

PubMed2007

The role of PDGF in radiation oncology.

Platelet-derived growth factor (PDGF) was originally identified as a constituent of blood serum and subsequently purified from human platelets. PDGF ligand is a dimeric molecule consisting of two disulfide-bonded chains from A-, B-, C- and D-polypeptide chains, which combine to homo- and heterodimers. The PDGF isoforms exert their cellular effects by binding to and activating two structurally related protein tyrosine kinase receptors. PDGF is a potent mitogen and chemoattractant for mesenchymal cells and also a chemoattractant for neutrophils and monocytes. In radiation oncology, PDGF are important for several pathologic processes, including oncogenesis, angiogenesis and fibrogenesis. Autocrine activation of PDGF was observed and interpreted as an important mechanism involved in brain and other tumors. PDGF has been shown to be fundamental for the stability of normal blood vessel formation, and may be essential for the angiogenesis in tumor tissue. PDGF also plays an important role in the proliferative disease, such as atherosclerosis and radiation-induced fibrosis, regarding its proliferative stimulation of fibroblast cells. Moreover, PDGF was also shown to stimulate production of extracellular matrix proteins, which are mainly responsible for the irreversibility of these diseases. This review introduces the structural and functional properties of PDGF and PDGF receptors and discusses the role and mechanism of PDGF signaling in normal and tumor tissues under different conditions in radiation oncology.

Animals↗

PubMed2007

Counting colonies of clonogenic assays by using densitometric software.

Clonogenic assays are a useful tool to test whether a given cancer therapy can reduce the clonogenic survival of tumour cells. A colony is defined as a cluster of at least 50 cells which can often only be determined microscopically. The process of counting colonies is very extensive work and so we developed software that is able to count the colonies automatically from scanned flasks. This software is made freely available by us with a detailed description how to use and install the necessary features.

Algorithms↗

PubMed2006

Isobologram analysis of triple therapies.

New concepts in radiation oncology are based on the concept that combinations of irradiation and molecular targeted drugs can yield synergistic or at least additive effects. Up to now the combination of two treatment modalities has been tested in almost all cases. Similar to conventional anti-cancer agents, the efficacy of targeted approaches is also subject to predefined resistance mechanisms. Therefore, it seems reasonable to speculate that a combination of more than two agents will ultimately increase the therapeutic gain. No tools for a bio-mathematical evaluation of a given degree of interaction for more than two anti-neoplastic agents are currently available. The present work introduces a new method for an evaluation of triple therapies and provides some graphical examples in order to visualize the results.

Algorithms↗

PubMed2006

Irradiation-induced pneumonitis mediated by the CD95/CD95-ligand system.

Pneumonitis is a dose-limiting side effect of radiotherapy. However, the underlying mechanisms of irradiation-induced pneumonitis are unclear. Several observations suggest that the CD95/CD95-ligand (CD95L) system is involved in this process. Therefore, we examined the development of pneumonitis in CD95- and CD95L-deficient and wild-type mice after single irradiation with 0 or 12.5 Gy by measuring breathing frequency, pulmonary resistance, and histopathologic changes. Although wild-type mice developed pathognomonic alterations characteristic of pneumonitis (judged by alveolar wall thickness, interstitial edema, and interstitial and peribronchial inflammation) that paralleled increased breathing frequency ratio on days 5-70 (P < .03) with a maximum at day 37 (12.5 Gy, mean ratio = 1.05, 95% confidence interval [CI] = 1.01 to 1.08; P = .004 versus 0 Gy, mean ratio = 0.997, 95% CI = 0.976 to 1.02; P = .05) and pulmonary resistance (day 42, 12.5 Gy, mean = 0.51, 95% CI = 0.44 to 0.58 versus 0 Gy, mean = 0.40, 95% CI = 0.32 to 0.47; P = .03) after irradiation, no such changes were detected in CD95- or CD95L-deficient mice. This report demonstrates for the first time, to our knowledge, that the CD95/CD95L system is important for the development of irradiation-induced pneumonitis.

Animals↗

PubMed2006

Increased cytotoxicity of ionizing radiation in combination with membrane-targeted apoptosis modulators involves downregulation of protein kinase B/Akt-mediated survival-signaling.

BACKGROUND AND PURPOSE: The membrane-targeted apoptosis modulators erucylphosphocholine (ErPC) and erucylphosphohomocholine (ErPC3) induce apoptosis in highly apoptosis resistant malignant glioma cell lines and enhance radiation-induced cell death and eradication of clonogenic tumor cells in vitro. Aim of the present study was to elucidate molecular mechanisms of combined action. MATERIALS AND METHODS: Induction of apoptosis was evaluated by determination of nuclear morphology (fluorescence microscopy), alteration of mitochondrial function and caspase-activation (flow cytometry, Western blot). Activity of protein kinase B (PKB/Akt) and key downstream effectors involved in apoptosis regulation was verified by Western blot analysis using activation-specific antibodies. RESULTS: Increased cytotoxicity of the combination was linked to a more efficient activation of the intrinsic apoptosis pathway with increased damage of the mitochondria and caspase-activation. Moreover, activity of the survival kinase PKB/Akt was downregulated upon treatment with ErPC/ErPC3 alone or in combination with ionizing radiation. Inhibition of PKB/Akt was associated with decreased phosphorylation and thus activation of the pro-apoptotic Bcl-2 protein Bad as well as dephosphorylation of the transcription factor FOXO3A (FKHRL1) that may be responsible for the observed increased expression of the pro-apoptotic Bcl-2 protein Bim. CONCLUSIONS: Our data suggest a role for inhibition of PKB/Akt-mediated anti-apoptotic signaling in increased efficacy of the combination.

Apoptosis↗

PubMed2006

The membrane targeted apoptosis modulators erucylphosphocholine and erucylphosphohomocholine increase the radiation response of human glioblastoma cell lines in vitro.

BACKGROUND: Alkylphosphocholines constitute a novel class of antineoplastic synthetic phospholipid derivatives that induce apoptosis of human tumor cell lines by targeting cellular membranes. We could recently show that the first intravenously applicable alkylphosphocholine erucylphosphocholine (ErPC) is a potent inducer of apoptosis in highly resistant human astrocytoma/glioblastoma cell lines in vitro. ErPC was shown to cross the blood brain barrier upon repeated intravenous injections in rats and thus constitutes a promising candidate for glioblastoma therapy. Aim of the present study was to analyze putative beneficial effects of ErPC and its clinically more advanced derivative erucylphosphohomocholine (erucyl-N, N, N-trimethylpropanolaminphosphate, ErPC3, Erufosinetrade mark on radiation-induced apoptosis and eradication of clonogenic tumor cells in human astrocytoma/glioblastoma cell lines in vitro. RESULTS: While all cell lines showed high intrinsic resistance against radiation-induced apoptosis as determined by fluorescence microscopy, treatment with ErPC and ErPC3 strongly increased sensitivity of the cells to radiation-induced cell death (apoptosis and necrosis). T98G cells were most responsive to the combined treatment revealing highly synergistic effects while A172 showed mostly additive to synergistic effects, and U87MG cells sub-additive, additive or synergistic effects, depending on the respective radiation-dose, drug-concentration and treatment time. Combined treatment enhanced therapy-induced damage of the mitochondria and caspase-activation. Importantly, combined treatment also increased radiation-induced eradication of clonogenic T98G cells as determined by standard colony formation assays. CONCLUSION: Our observations make the combined treatment with ionizing radiation and the membrane targeted apoptosis modulators ErPC and ErPC3 a promising approach for the treatment of patients suffering from malignant glioma. The use of this innovative treatment concept in an in vivo xenograft setting is under current investigation.

Journal Article↗

PubMed2006

Why "radiation oncology".

Radiotherapy continues to be a major treatment for solid tumours and is a cornerstone of modern oncology. The term 'radiation oncology' describes the integration of radiation therapy into the complexity of multi-modal therapy. Over the last ten years the crucial role of radiation therapy as part of multi-modality protocols in cancer care has been documented in numerous Phase III trials. Advances in treatment technology as well as the underlying biology of tumour resistance mechanisms will further strengthen the role of radiation oncology. The scientific role of radiation oncology is reflected by the increase in the number of papers related to radiation oncology in resources like Medline. In order to reflect the growing scientific importance of radiation oncology, radiation physics and radiation biology, we have initiated Radiation Oncology as the first open access journal in the field. Open access allows for a rapid and transparent publication process together with an unequalled opportunity to reach the widest reader spectrum possible.

Access to Information↗

PubMed2006

Proapoptotic activity of Ukrain is based on Chelidonium majus L. alkaloids and mediated via a mitochondrial death pathway.

BACKGROUND: The anticancer drug Ukrain (NSC-631570) which has been specified by the manufacturer as semisynthetic derivative of the Chelidonium majus L. alkaloid chelidonine and the alkylans thiotepa was reported to exert selective cytotoxic effects on human tumour cell lines in vitro. Few clinical trials suggest beneficial effects in the treatment of human cancer. Aim of the present study was to elucidate the importance of apoptosis induction for the antineoplastic activity of Ukrain, to define the molecular mechanism of its cytotoxic effects and to identify its active constituents by mass spectrometry. METHODS: Apoptosis induction was analysed in a Jurkat T-lymphoma cell model by fluorescence microscopy (chromatin condensation and nuclear fragmentation), flow cytometry (cellular shrinkage, depolarisation of the mitochondrial membrane potential, caspase-activation) and Western blot analysis (caspase-activation). Composition of Ukrain was analysed by mass spectrometry and LC-MS coupling. RESULTS: Ukrain turned out to be a potent inducer of apoptosis. Mechanistic analyses revealed that Ukrain induced depolarisation of the mitochondrial membrane potential and activation of caspases. Lack of caspase-8, expression of cFLIP-L and resistance to death receptor ligand-induced apoptosis failed to inhibit Ukrain-induced apoptosis while lack of FADD caused a delay but not abrogation of Ukrain-induced apoptosis pointing to a death receptor independent signalling pathway. In contrast, the broad spectrum caspase-inhibitor zVAD-fmk blocked Ukrain-induced cell death. Moreover, over-expression of Bcl-2 or Bcl-xL and expression of dominant negative caspase-9 partially reduced Ukrain-induced apoptosis pointing to Bcl-2 controlled mitochondrial signalling events. However, mass spectrometric analysis of Ukrain failed to detect the suggested trimeric chelidonine thiophosphortriamide or putative dimeric or monomeric chelidonine thiophosphortriamide intermediates from chemical synthesis. Instead, the Chelidonium majus L. alkaloids chelidonine, sanguinarine, chelerythrine, protopine and allocryptopine were identified as major components of Ukrain. Apart from sanguinarine and chelerythrine, chelidonine turned out to be a potent inducer of apoptosis triggering cell death at concentrations of 0.001 mM, while protopine and allocryptopine were less effective. Similar to Ukrain, apoptosis signalling of chelidonine involved Bcl-2 controlled mitochondrial alterations and caspase-activation. CONCLUSION: The potent proapoptotic effects of Ukrain are not due to the suggested "Ukrain-molecule" but to the cytotoxic efficacy of Chelidonium majus L. alkaloids including chelidonine.

Alkaloids↗

PubMed2006

First experiences of radiation treatment planning with PET/CT.

BACKGROUND: Positron emission tomography/computed tomography (PET/CT) is composed of modern CT and PET technology in one machine enabling examinations of patients in one session in the same position. Its value for modern radiation treatment planning is under investigation. METHODS: In 53 patients with head-and-neck (n = 11), non-small cell lung (n = 16), prostate (n = 14) and other cancers (n = 12), a PET/CT investigation was performed. During the diagnostic examination process an integrated scan under radiation treatment-planning conditions was included. Interpretation and delineation of macroscopic tumor were done in an interdisciplinary approach. Treatment changes occurred after critical interpretation of the PET/CT findings by the responsible radiotherapist. Analysis is descriptive with regard to changes in treatment intention, mode, radiation volumes and doses. RESULTS: Examinations were well tolerated. CT datasets in treatment position could be used for planning. Delineation of macroscopic tumor led to changes of the planning target volume after PET/CT 15 times, total dose was modified twelve times. PET/CT examinations led to changes of the general treatment mode in 19 cases. Using the separate CT and PET datasets, fusion in the planning software was easily performed in all patients due to the use of the same positioning and immobilization devices in PET/CT. CONCLUSION: Despite the low number of patients and an expected bias of selection, the first results are encouraging to perform more extended and detailed trials of this technology in radiotherapy planning. Whether PET/CT is superior to PET alone is part of ongoing investigations.

Adult↗

PubMed2006

Total-body irradiation--role and indications: results from the German Registry for Stem Cell Transplantation (DRST).

BACKGROUND AND PURPOSE: Total-body irradiation (TBI) is a key part of the conditioning regimen before hematopoietic stem cell transplantation (HSCT). The exact role of TBI as part of the conditioning regimen is largely unclear. In order to determine the relevance of TBI, the status of TBI utilization was analyzed on the basis of a nationwide registry. MATERIAL AND METHODS: 14,371 patients (1998-2002) documented in the German Stem Cell Transplantation Registry (DRST) were analyzed regarding TBI utilization prior to autologous or allogeneic transplantation, underlying disorder, type of donor, stem cell source, and size of the treatment center. RESULTS: For autologous HSCT approximately 10% of the patients (873/8,167) received TBI, with chronic lymphocytic leukemia (CLL, approximately 80%, 171/214) and low-grade non-Hodgkin's lymphoma (l-NHL, approximately 35%, 330/929) being the most important disorders. In the allogeneic setting 50% of the patients (2,399/4,904) received TBI, with acute lymphocytic leukemia (ALL, 85%, 794/930), acute myeloid leukemia (AML, 45%, 662/1,487) and chronic myeloid leukemia (CML, 49%, 561/1,156) being the key indications. The type of donor, stem cell source and center size did not strongly influence the use of TBI. CONCLUSION: TBI has only a limited role for the conditioning prior to autologous HCST. For allogeneic HSCT TBI is widely accepted with no major changes over the observation time. The use of TBI is generally accepted for ALL, whereas approximately half of the patients with CML or AML received TBI. Although a considerably large database was analyzed, no clear determinants for the use of TBI could be distinguished.

Acute Disease↗

PubMed2005

A normal tissue dose response model of dynamic repair processes.

A model is presented for serial, critical element complication mechanisms for irradiated volumes from length scales of a few millimetres up to the entire organ. The central element of the model is the description of radiation complication as the failure of a dynamic repair process. The nature of the repair process is seen as reestablishing the structural organization of the tissue, rather than mere replenishment of lost cells. The interactions between the cells, such as migration, involved in the repair process are assumed to have finite ranges, which limits the repair capacity and is the defining property of a finite-sized reconstruction unit. Since the details of the repair processes are largely unknown, the development aims to make the most general assumptions about them. The model employs analogies and methods from thermodynamics and statistical physics. An explicit analytical form of the dose response of the reconstruction unit for total, partial and inhomogeneous irradiation is derived. The use of the model is demonstrated with data from animal spinal cord experiments and clinical data about heart, lung and rectum. The three-parameter model lends a new perspective to the equivalent uniform dose formalism and the established serial and parallel complication models. Its implications for dose optimization are discussed.

Animals↗

PubMed2005

Treatment-outcome for synchronous head-and-neck and oesophageal squamous cell carcinoma.

BACKGROUND AND PURPOSE: Although head & neck and oesophageal carcinomas occur synchronously in up to 12%, almost no data on feasibility and outcome after radiotherapy are available. MATERIALS AND METHODS: From 1989 to 2002, 24 patients were treated at Tuebingen University and Fulda hospital with a radiation based, curative approach. These were analyzed retrospectively. RESULTS: The median overall survival was 37 (1-69) months with a few long-term survivors with a median follow-up of 26 months for patients at risk. 7 local recurrences occurred. No major toxicity was seen. DISCUSSION: Even though the prognosis of synchronous head & neck and oesophageal carcinomas is grim, long-term survival is possible. A radiation-based approach is feasible and can be chosen for a curative treatment approach which we recommend.

Aged↗

PubMed2005

Array-based comparative gene expression analysis of tumor cells with increased apoptosis resistance after hypoxic selection.

Tumor hypoxia is an adverse prognostic factor. In a recent study, we could demonstrate that cyclic hypoxia selects for hypoxia-tolerant tumor cells, which are cross-resistant to other stimuli of mitochondrial death pathways. In contrast, sensitivity of the cells to death-receptor ligands was mainly not affected. The aim of the present study was to further elucidate cellular changes induced by cyclic hypoxia and to identify alterations in gene expression pattern upon hypoxic selection by means of DNA-microarray analysis. Our data reveal that cyclic hypoxia resulted in the selection of cells with resistance to doxorubicine and radiation. Furthermore, hypoxic selection was accompanied by constitutive changes of the gene expression pattern with downregulation of 156 and upregulation of 82 genes. Most of the differentially regulated genes were involved in cellular responses to hypoxia and reoxygenation. While many of the genes that were downregulated upon hypoxic selection represent genes that are usually upregulated by acute hypoxia, the genes that were upregulated represent genes that are involved in stress resistance and anti-apoptotic signalling. Most importantly, hypoxic selection was not associated with changes of single apoptosis relevant genes, but with alterations in gene expression levels of a wide variety of genes indicating a more complex adaptation process.

Apoptosis↗

PubMed2005

Intensity modulated radiotherapy for high risk prostate cancer based on sentinel node SPECT imaging for target volume definition.

BACKGROUND: The RTOG 94-13 trial has provided evidence that patients with high risk prostate cancer benefit from an additional radiotherapy to the pelvic nodes combined with concomitant hormonal ablation. Since lymphatic drainage of the prostate is highly variable, the optimal target volume definition for the pelvic lymph nodes is problematic. To overcome this limitation, we tested the feasibility of an intensity modulated radiation therapy (IMRT) protocol, taking under consideration the individual pelvic sentinel node drainage pattern by SPECT functional imaging. METHODS: Patients with high risk prostate cancer were included. Sentinel nodes (SN) were localised 1.5-3 hours after injection of 250 MBq 99mTc-Nanocoll using a double-headed gamma camera with an integrated X-Ray device. All sentinel node localisations were included into the pelvic clinical target volume (CTV). Dose prescriptions were 50.4 Gy (5 x 1.8 Gy / week) to the pelvis and 70.0 Gy (5 x 2.0 Gy / week) to the prostate including the base of seminal vesicles or whole seminal vesicles. Patients were treated with IMRT. Furthermore a theoretical comparison between IMRT and a three-dimensional conformal technique was performed. RESULTS: Since 08/2003 6 patients were treated with this protocol. All patients had detectable sentinel lymph nodes (total 29). 4 of 6 patients showed sentinel node localisations (total 10), that would not have been treated adequately with CT-based planning ('geographical miss') only. The most common localisation for a probable geographical miss was the perirectal area. The comparison between dose-volume-histograms of IMRT- and conventional CT-planning demonstrated clear superiority of IMRT when all sentinel lymph nodes were included. IMRT allowed a significantly better sparing of normal tissue and reduced volumes of small bowel, large bowel and rectum irradiated with critical doses. No gastrointestinal or genitourinary acute toxicity Grade 3 or 4 (RTOG) occurred. CONCLUSION: IMRT based on sentinel lymph node identification is feasible and reduces the probability of a geographical miss. Furthermore, IMRT allows a pronounced sparing of normal tissue irradiation. Thus, the chosen approach will help to increase the curative potential of radiotherapy in high risk prostate cancer patients.

Aged↗

PubMed2005

TRAIL sensitizes for ionizing irradiation-induced apoptosis through an entirely Bax-dependent mitochondrial cell death pathway.

The death ligand TRAIL has been suggested as a suitable biological agent for the selective induction of cell death in cancer cells. Moreover, TRAIL synergizes with DNA-damaging therapies such as chemotherapeutic drugs or ionizing irradiation (IR). Here, we show that synergy of TRAIL and IR, that is, crosssensitization between TRAIL and IR for induction of apoptosis, entirely depends on Bax proficiency in human DU145 and HCT116 carcinoma cells. DU145 prostate carcinoma cells that have lost Bax protein expression due to mutation fail to activate caspase-3 and -9 when exposed to TRAIL and IR. In contrast, TRAIL sensitized for IR-induced apoptosis and vice versa upon reconstitution of Bax expression. Notably, both DU145 and HCT116 still express significant levels of the multidomain proapoptotic Bcl-2 homolog Bak. This indicates that Bak is not sufficient to mediate crosssensitization and synergism between IR and TRAIL. These data clearly establish distinct roles for Bax and Bak in linking the TRAIL death receptor pathway to the mitochondrial apoptosis signaling cascade upon DNA damage by IR.

Apoptosis↗

PubMed2005

Cooperative cytotoxicity of proteasome inhibitors and tumor necrosis factor-related apoptosis-inducing ligand in chemoresistant Bcl-2-overexpressing cells.

PURPOSE: Bcl-2 overexpression is frequently detected in lymphoid malignancies, being associated with poor prognosis and reduced response to therapy. Here, we evaluated whether Bcl-2 overexpression affects the cytotoxic activity of proteasome inhibitors taken alone or in association with conventional anticancer drugs or tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). EXPERIMENTAL DESIGN: Jurkat cells engineered to overexpress Bcl-2 were treated with proteasome inhibitors (MG132, epoxomicin, and bortezomib), anticancer drugs (etoposide and doxorubicin), TRAIL, or combinations of these compounds. Cell death and loss of mitochondrial transmembrane potential were detected by flow cytometry. Cytosolic relocalization of cytochrome c and SMAC/Diablo, caspase cleavage, and Bcl-2 and Mcl-1 levels were determined by immunoblotting. Nuclear factor-kappaB inhibition was done by retroviral transduction with a dominant-negative mutant of IkappaBalpha. RESULTS: Bcl-2 overexpression results in significant inhibition of apoptosis in response to proteasome inhibitors, antiblastics, and TRAIL. Addition of TRAIL to proteasome inhibitors results in a synergistic cytotoxic effect in Bcl-2-overexpressing cells, whereas this result is not reproduced by the combination of proteasome inhibitors with antiblastic drugs. Importantly, proteasome inhibitors plus TRAIL induce mitochondrial dysfunction irrespective of up-regulated Bcl-2. Bcl-2 cleavage to a fragment with putative proapoptotic activity and elimination of antiapoptotic Mcl-1 may both play a role in proteasome inhibitors-TRAIL cooperation. Conversely, nuclear factor-kappaB inhibition by proteasome inhibitors is per se insufficient to explain the observed synergy. CONCLUSIONS: Combined proteasome inhibitors and TRAIL overcome the apoptotic threshold raised by Bcl-2 and may prove useful in the treatment of chemoresistant malignancies with up-regulated Bcl-2.

Antineoplastic Agents↗

PubMed2005

Reirradiation alternating with docetaxel and cisplatin in inoperable recurrence of head-and-neck cancer: a prospective phase I/II trial.

PURPOSE: Inoperable locoregional recurrences of head-and-neck cancer in a previously irradiated volume represent a therapeutic dilemma. Chemotherapy alone has no curative potential, whereas reirradiation and concurrent chemoradiation can salvage a small fraction of patients. Mucosal toxicity of concurrent chemoradiation requires substantial dose reduction of chemotherapy. Alternating chemoradiation offers the chance to give both full-dose chemotherapy and radiotherapy. The latter may provide a particular advantage for recurrent, potentially radiation resistant tumors. The feasibility and efficacy of a full-dose docetaxel containing alternating chemoradiation schedule was tested. PATIENTS AND METHODS: Twenty-seven patients (Karnofsky performance status score >/=70%) with histologically proven recurrent squamous cell cancer that occurred >/= 6 months in a previously irradiated area (>/= 60 Gy) were considered unresectable and unsuitable for brachytherapy. Alternating chemoradiation consisted of 3 cycles of docetaxel 60 mg/m(2) d1 and cisplatin 15 mg/m(2) d2-5, q d22, and involved field radiotherapy 2.0 Gy every day d8-12, d15-19, d29-33, and d36-40 (40.0 Gy total dose). Dose reduction of docetaxel to 50 mg/m(2) was necessary, because of hematologic toxicity in the first 12 patients. RESULTS: Alternating chemoreirradiation was applied as planned in 12 of 27 patients, with reirradiation completed per protocol in 81%. Overall, patients received 83% of the intended dose of docetaxel and 73% of cisplatin. Third-degree common toxicity criteria mucositis occurred in 15%, leukopenia of >/= third degree by common toxicity criteria in 37%, and 3 early deaths were observed. Median time to follow-up, time to local progression, median survival, and 3-year survival rates were 42 months, 10 months, 10 months, and 18%, respectively. CONCLUSIONS: Alternating chemoreirradiation in recurrences of head-and-neck cancer resulted in 80% overall response with acceptable toxicity. A significant minority of patients had durable tumor control with a chance of long-term survival.

Adult↗

PubMed2005

Irradiation specifically sensitises solid tumour cell lines to TRAIL mediated apoptosis.

BACKGROUND: TRAIL (tumor necrosis factor related apoptosis inducing ligand) is an apoptosis inducing ligand with high specificity for malignant cell systems. Combined treatment modalities using TRAIL and cytotoxic drugs revealed highly additive effects in different tumour cell lines. Little is known about the efficacy and underlying mechanistic effects of a combined therapy using TRAIL and ionising radiation in solid tumour cell systems. Additionally, little is known about the effect of TRAIL combined with radiation on normal tissues. METHODS: Tumour cell systems derived from breast- (MDA MB231), lung--(NCI H460) colorectal--(Colo 205, HCT-15) and head and neck cancer (FaDu, SCC-4) were treated with a combination of TRAIL and irradiation using two different time schedules. Normal tissue cultures from breast, prostate, renal and bronchial epithelia, small muscle cells, endothelial cells, hepatocytes and fibroblasts were tested accordingly. Apoptosis was determined by fluorescence microscopy and western blot determination of PARP processing. Upregulation of death receptors was quantified by flow cytometry. RESULTS: The combined treatment of TRAIL with irradiation strongly increased apoptosis induction in all treated tumour cell lines compared to treatment with TRAIL or irradiation alone. The synergistic effect was most prominent after sequential application of TRAIL after irradiation. Upregulation of TRAIL receptor DR5 after irradiation was observed in four of six tumour cell lines but did not correlate to tumour cell sensitisation to TRAIL. TRAIL did not show toxicity in normal tissue cell systems. In addition, pre-irradiation did not sensitise all nine tested human normal tissue cell cultures to TRAIL. CONCLUSIONS: Based on the in vitro data, TRAIL represents a very promising candidate for combination with radiotherapy. Sequential application of ionising radiation followed by TRAIL is associated with an synergistic induction of cell death in a large panel of solid tumour cell lines. However, TRAIL receptor upregulation may not be the sole mechanism by which sensitation to TRAIL after irradiation is induced.

Antineoplastic Agents↗