title: Relevance of MET activation and genetic alterations of KRAS and E-cadherin for cetuximab sensitivity of gastric cancer cell lines.
abstract: OBJECTIVE
  The therapeutic activity of the epidermal growth factor receptor (EGFR)-directed monoclonal antibody cetuximab in gastric cancer is currently being investigated. Reliable biomarkers for the identification of patients who are likely to benefit from the treatment are not available. The aim of the study was to examine the drug sensitivity of five gastric cancer cell lines towards cetuximab as a single agent and to establish predictive markers for chemosensitivity in this cell culture model. The effect of a combination of cetuximab with chemotherapy was compared between a sensitive and a nonsensitive cell line.
  
  
  METHODS
  EGFR expression, activation and localisation, the presence and subcellular localisation of the cell adhesion molecule E-cadherin as well as MET activation were examined by Western blot analysis, flow cytometry and immunofluorescence staining. Cells were treated with varying concentrations of cetuximab and cisplatin and 5-fluorouracil in tumour-relevant concentrations. The biological endpoint was cell viability, which was measured by XTT cell proliferation assay. Response to treatment was evaluated using statistical methods.
  
  
  RESULTS
  We assessed the activity of cetuximab in five gastric cancer cell lines (AGS, KATOIII, MKN1, MKN28 and MKN45). The viability of two cell lines, MKN1 and MKN28, was significantly reduced by cetuximab treatment. High EGFR expression and low levels of receptor activation were associated with cetuximab responsiveness. MET activation as well as mutations of KRAS and CDH1 (gene encoding E-cadherin) was associated with cetuximab resistance.
  
  
  CONCLUSIONS
  These data indicate that our examinations may be clinically relevant, and the candidate markers should therefore be tested in clinical studies.
authors.affiliation: Institut für Allgemeine Pathologie und Pathologische Anatomie, Technische Universität München, Klinikum rechts der Isar, Trogerstr. 18, 81675, Munich, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Heindl
authors.forename: Evelyn
authors.initials: E
authors.lastname: Eggenstein
authors.forename: Simone
authors.initials: S
authors.lastname: Keller
authors.forename: Julia
authors.initials: J
authors.lastname: Kneissl
authors.forename: Gisela
authors.initials: G
authors.lastname: Keller
authors.forename: Kathrin
authors.initials: K
authors.lastname: Mutze
authors.forename: Sandra
authors.initials: S
authors.lastname: Rauser
authors.forename: Georg
authors.initials: G
authors.lastname: Gasteiger
authors.forename: Ingo
authors.initials: I
authors.lastname: Drexler
authors.forename: Alexander
authors.initials: A
authors.lastname: Hapfelmeier
authors.forename: Heinz
authors.initials: H
authors.lastname: Höfler
authors.forename: Birgit
authors.initials: B
authors.lastname: Luber
mesh_terms: D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology*; D015703:Antigens, CD; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D014408:Biomarkers, Tumor; D015153:Blotting, Western; D015820:Cadherins / Q000235:genetics*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D000068818:Cetuximab; D002945:Cisplatin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D066246:ErbB Receptors / Q000378:metabolism; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D005472:Fluorouracil / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D006801:Humans; D009154:Mutation; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D019859:Proto-Oncogene Proteins c-met / Q000235:genetics / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras); D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D018631:ras Proteins / Q000235:genetics*
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D015703:Antigens, CD; D014408:Biomarkers, Tumor; C513384:CDH1 protein, human; D015820:Cadherins; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D066246:ErbB Receptors; C491743:MET protein, human; D019859:Proto-Oncogene Proteins c-met; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins; D000068818:Cetuximab; D002945:Cisplatin; D005472:Fluorouracil