title: EGFR and β1-integrin targeting differentially affect colorectal carcinoma cell radiosensitivity and invasion.
abstract: OBJECTIVE
  Simultaneous targeting of β1 integrin receptor and epidermal growth factor receptor (EGFR) showed higher level of radiosensitization in head and neck cancers than monotherapies. As EGFR inhibition is similarly performed in colorectal cancer (CRC), we investigated the radiosensitizing and anti-invasive potential of β1-integrin/EGFR inhibition in CRC cell lines grown in more physiological three-dimensional (3D) matrix-based cell cultures.
  
  
  METHODS
  DLD-1 and HT-29 cells were used for 3D-colony formation, invasion and proliferation assays and Western blotting. β1 integrin, focal adhesion kinase and EGFR were inhibited by AIIB2, TAE226 and Cetuximab, respectively. KRAS and BRAF knockdown were accomplished using small-interfering RNA technology. Single doses of X-rays ranged from 2Gy to 6Gy and 5-fluorouracil (5-FU) concentration was 10μM.
  
  
  RESULTS
  Neither β1-integrin/EGFR inhibition nor KRAS or BRAF depletion nor 5-FU significantly modified CRC cell radiosensitivity. Cetuximab, AIIB2 and Cetuximab/AIIB2 differentially modulated MAPK, JNK and AKT phosphorylation. AIIB2 and TAE226 significantly decreased cell invasion.
  
  
  CONCLUSIONS
  Our data show inefficiency of Cetuximab and AIIB2 on top of radiochemotherapy. The functions of KRAS and BRAF in therapy resistance remain unanswered and warrant further preclinical molecular-driven investigations. One promising approach might be β1 integrin targeting for reducing metastatic CRC cell spread.
authors.affiliation: OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf, Germany.
authors.forename: Mandy
authors.initials: M
authors.lastname: Poschau
authors.affiliation: OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf, Germany.
authors.forename: Ellen
authors.initials: E
authors.lastname: Dickreuter
authors.affiliation: OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf, Germany.
authors.forename: Jenny
authors.initials: J
authors.lastname: Singh-Müller
authors.affiliation: OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Zscheppang
authors.affiliation: OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf, Germany; Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, USA.
authors.forename: Iris
authors.initials: I
authors.lastname: Eke
authors.affiliation: University Medical Center, General, Visceral and Paediatric Surgery, University Göttingen, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Liersch
authors.affiliation: OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf, Germany; Department of Radiation Oncology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany; Helmholtz-Zentrum Dresden - Rossendorf, Institute of Radiooncology, Germany; German Cancer Consortium (DKTK), Dresden, Germany; German Cancer Research Center (DKFZ), Heidelberg, Germany. Electronic address: Nils.Cordes@OncoRay.de.
authors.forename: Nils
authors.initials: N
authors.lastname: Cordes
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D000068818:Cetuximab / Q000494:pharmacology; D015179:Colorectal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D005472:Fluorouracil / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D019073:HT29 Cells; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D034741:RNA, Small Interfering / Q000494:pharmacology; D011836:Radiation Tolerance / Q000187:drug effects; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D019012:Integrin beta1; D034741:RNA, Small Interfering; D011838:Radiation-Sensitizing Agents; D066246:ErbB Receptors; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D000068818:Cetuximab; D005472:Fluorouracil
keywords: Colorectal carcinoma; EGFR; Invasion; Ionizing radiation; β1 integrin