- Email: [email protected]
421 Technique dependence of rectal complications in external beam radiotherapy for prostate cancer
$190 Wednesday, October 27, 2004
Symposia
and short (< 3 months), long (> 3months) neo-adjuvant HT and adjuvant HT are possibly 3 different groups. For late GI and GU toxicity, pre-treatment surgical procedures (abdominal surgery and TURP, respectively) have a major adverse effect. For both acute and late rectum toxicity (especially rectal bleeding), a volume effect has been demonstrated. For both intermediate and high dose levels, higher volumes irradiated to at least that dose level, result in more complications. It is not evident that the maximum rectal dose is an independent prognostic factor. The concept of Effective Uniform Dose to quantify the relation between rectum complications and the DVH is being pursued. The relation of bladder complications and DVH parameters is less clear. Conclusions: The incidence of acute and late rectum and bladder complications can be estimated from DVH parameters, together with other treatment and patient specific factors. 421 Technique dependence of rectal complications in external beam radiotherapy for prostate cancer A. Jackson Memorial Sloan-Kettering Cancer Ctr, Dept of Medical Physics, New York, USA Late rectal bleeding is the dose limiting complication in the treatment of prostate cancer with external beam radiotherapy. 3D Conformal and IMRT treatments can greatly decrease clinical incidence of this complication, provided attention is paid to proper clinical technique. The use of CT scans for planning, and adoption custom blocking or intensity modulation of beam portals do not, of themselves, guarantee a satisfactory outcome, since these tools are extremely flexible, and have provided treatment possibilities outside previous clinical experience. The initial use of these tools in a variety of dose escalation protocols has yielded a range of outcomes that provide guidance for their proper use. Clinical data on the incidence of late rectal bleeding from 2-D, 3-D and IMRT treatments will be reviewed and evidence for the dose, volume and technique dependence of this complication will be presented.
Role of extracellular sensitivity
matrix
in
RT
422 The effect of X-rays on synthesis and deposition of ECM proteins in vivo E. Giannopoulou I, M. Hatziapostolof , D. Kardamakis 2, E~ Papadimitriof 1University of Patras, Lab. of Mol. Pharmacology, Patras, Greece 2University of Patras, Dept. of Radiotherapy, Patras, Greece Introduction: Specialized microenvironments composed of insoluble extracellular matrix (ECM) and soluble growth factors play a pivotal role in normal tissue development and function. Remodelling and proteolytic cleavage of ECM components by metalloproteinases (MMPs) modifies celI-ECM interactions and is related to normal physiological processes and pathological conditions. In the present work, we studied the effect of X rays on the expression and deposition of ECM proteins that are related to formation and maturation of new blood vessels. Methods: The in vivo model of chicken embryo chorioallantoic membrane (CAM) was used. An area of 1 cm 2 of the CAM, restricted by a plastic ring, was irradiated at room temperature, using a RT 50 mobile contact therapy unit, with 20 kV X rays. The SSD was 4 cm and the dose rate 2,600 cGy per min. A
single dose of 10 Gy was used, which did not affect viability of the embryos. The deposition of ECM proteins was studied using Western blot analysis of CAM protein extracts. The amounts of integrin avl33 protein were measured by ELISA and the amounts and activation of MMP-2 by zymography. The expression of the corresponding genes was studied using RT-PCR. Results: The deposited amounts of fibronectin, laminin, collagen type I, integrin e43 3, and MMP-2 were decreased 6 h after irradiation, while collagen type IV was not affected. A similar decrease was observed on the gene expression of fibronectin, laminin, collagen type I and MMP-2, 6h after irradiation. The gene expression of collagen type IV and integrin avl33 was not affected by X rays up to 24h after irradiation. The decrease in both protein and mRNA levels was reversed at later time points and 48 h after irradiation, there was a significant increase in the expression of all the genes studied. Conclusion: Although X rays have an inhibitory effect on the synthesis and deposition of ECM proteins up to 24h after irradiation, at later time points this effect is reversed and synthesis of ECM proteins is enhanced. This is an indication of activation of pathways that may finally lead to an increase in both normal and tumour induced angiogenesis. 423 Effect of ECM proteins on cellular radiation sensitivity in vitro N. Cordes Bundeswehr Institute of Radiobiology, Munich, Germany Extracellular matrix proteins are part of the microenvironment that surrounds all cells. Interactions between cells and matrix proteins are mainly facilitated by the integrin family of cell adhesion molecules. To date 18 c~ and 8 c~ integrin subunits are known to form 24 different (z/13-heterodimers in dependence on cell type and cellular context. Besides adhesion events, integrins participate in the regulation of various critical cell functions, i.e. survival, proliferation, differentiation, migration etc., by activation of cytoplasmic protein kinases, adapter proteins, GTPases and second messengers. Our investigations in a large panel of normal human fibroblasts and transformed cell lines uncovered specific integrin-mediated signals via integrin-linked kinase (ILK) and focal adhesion kinase (FAK) that modify the cellular radiation response. In contrast to the non-receptor associated FAK, ILK is bound to the cytoplasmic domains of 131-, ![32- and ~3-integrins. After irradiation, ILK and FAK differentially activate cellular survival and death pathways in tight conjunction with growth factor receptor-mediated signaling. In addition to the identification of integrin-mediated survival-advantaging effects in irradiated cells, our findings demonstrate a connection between adhesion events, cytoskeletal organization and cellular radiosensitivity in dependence on ILK. Taken together, our studies further underscore and define the important role of cell-matrix interactions in modulating the cellular response to genotoxic stress. These events are mediated by integrin signaling cascades. A better understanding of the underlying molecular mechanisms will hopefully promote innovative radiotherapeutic approaches. 424 Role of extracellular matrix in radiotherapy sensitivity W. Wick Universit~tsklinikum TObingen, Department of Neurology an Hertie-lnstitute for Clinical Brain Research, TfJbingen, Germany In addition to its antitumor effects, sublethal doses of irradiation enhance the invasiveness of human malignant glioma cells in
Symposia
and short (< 3 months), long (> 3months) neo-adjuvant HT and adjuvant HT are possibly 3 different groups. For late GI and GU toxicity, pre-treatment surgical procedures (abdominal surgery and TURP, respectively) have a major adverse effect. For both acute and late rectum toxicity (especially rectal bleeding), a volume effect has been demonstrated. For both intermediate and high dose levels, higher volumes irradiated to at least that dose level, result in more complications. It is not evident that the maximum rectal dose is an independent prognostic factor. The concept of Effective Uniform Dose to quantify the relation between rectum complications and the DVH is being pursued. The relation of bladder complications and DVH parameters is less clear. Conclusions: The incidence of acute and late rectum and bladder complications can be estimated from DVH parameters, together with other treatment and patient specific factors. 421 Technique dependence of rectal complications in external beam radiotherapy for prostate cancer A. Jackson Memorial Sloan-Kettering Cancer Ctr, Dept of Medical Physics, New York, USA Late rectal bleeding is the dose limiting complication in the treatment of prostate cancer with external beam radiotherapy. 3D Conformal and IMRT treatments can greatly decrease clinical incidence of this complication, provided attention is paid to proper clinical technique. The use of CT scans for planning, and adoption custom blocking or intensity modulation of beam portals do not, of themselves, guarantee a satisfactory outcome, since these tools are extremely flexible, and have provided treatment possibilities outside previous clinical experience. The initial use of these tools in a variety of dose escalation protocols has yielded a range of outcomes that provide guidance for their proper use. Clinical data on the incidence of late rectal bleeding from 2-D, 3-D and IMRT treatments will be reviewed and evidence for the dose, volume and technique dependence of this complication will be presented.
Role of extracellular sensitivity
matrix
in
RT
422 The effect of X-rays on synthesis and deposition of ECM proteins in vivo E. Giannopoulou I, M. Hatziapostolof , D. Kardamakis 2, E~ Papadimitriof 1University of Patras, Lab. of Mol. Pharmacology, Patras, Greece 2University of Patras, Dept. of Radiotherapy, Patras, Greece Introduction: Specialized microenvironments composed of insoluble extracellular matrix (ECM) and soluble growth factors play a pivotal role in normal tissue development and function. Remodelling and proteolytic cleavage of ECM components by metalloproteinases (MMPs) modifies celI-ECM interactions and is related to normal physiological processes and pathological conditions. In the present work, we studied the effect of X rays on the expression and deposition of ECM proteins that are related to formation and maturation of new blood vessels. Methods: The in vivo model of chicken embryo chorioallantoic membrane (CAM) was used. An area of 1 cm 2 of the CAM, restricted by a plastic ring, was irradiated at room temperature, using a RT 50 mobile contact therapy unit, with 20 kV X rays. The SSD was 4 cm and the dose rate 2,600 cGy per min. A
single dose of 10 Gy was used, which did not affect viability of the embryos. The deposition of ECM proteins was studied using Western blot analysis of CAM protein extracts. The amounts of integrin avl33 protein were measured by ELISA and the amounts and activation of MMP-2 by zymography. The expression of the corresponding genes was studied using RT-PCR. Results: The deposited amounts of fibronectin, laminin, collagen type I, integrin e43 3, and MMP-2 were decreased 6 h after irradiation, while collagen type IV was not affected. A similar decrease was observed on the gene expression of fibronectin, laminin, collagen type I and MMP-2, 6h after irradiation. The gene expression of collagen type IV and integrin avl33 was not affected by X rays up to 24h after irradiation. The decrease in both protein and mRNA levels was reversed at later time points and 48 h after irradiation, there was a significant increase in the expression of all the genes studied. Conclusion: Although X rays have an inhibitory effect on the synthesis and deposition of ECM proteins up to 24h after irradiation, at later time points this effect is reversed and synthesis of ECM proteins is enhanced. This is an indication of activation of pathways that may finally lead to an increase in both normal and tumour induced angiogenesis. 423 Effect of ECM proteins on cellular radiation sensitivity in vitro N. Cordes Bundeswehr Institute of Radiobiology, Munich, Germany Extracellular matrix proteins are part of the microenvironment that surrounds all cells. Interactions between cells and matrix proteins are mainly facilitated by the integrin family of cell adhesion molecules. To date 18 c~ and 8 c~ integrin subunits are known to form 24 different (z/13-heterodimers in dependence on cell type and cellular context. Besides adhesion events, integrins participate in the regulation of various critical cell functions, i.e. survival, proliferation, differentiation, migration etc., by activation of cytoplasmic protein kinases, adapter proteins, GTPases and second messengers. Our investigations in a large panel of normal human fibroblasts and transformed cell lines uncovered specific integrin-mediated signals via integrin-linked kinase (ILK) and focal adhesion kinase (FAK) that modify the cellular radiation response. In contrast to the non-receptor associated FAK, ILK is bound to the cytoplasmic domains of 131-, ![32- and ~3-integrins. After irradiation, ILK and FAK differentially activate cellular survival and death pathways in tight conjunction with growth factor receptor-mediated signaling. In addition to the identification of integrin-mediated survival-advantaging effects in irradiated cells, our findings demonstrate a connection between adhesion events, cytoskeletal organization and cellular radiosensitivity in dependence on ILK. Taken together, our studies further underscore and define the important role of cell-matrix interactions in modulating the cellular response to genotoxic stress. These events are mediated by integrin signaling cascades. A better understanding of the underlying molecular mechanisms will hopefully promote innovative radiotherapeutic approaches. 424 Role of extracellular matrix in radiotherapy sensitivity W. Wick Universit~tsklinikum TObingen, Department of Neurology an Hertie-lnstitute for Clinical Brain Research, TfJbingen, Germany In addition to its antitumor effects, sublethal doses of irradiation enhance the invasiveness of human malignant glioma cells in