title: Antibody-mediated delivery of anti-KRAS-siRNA in vivo overcomes therapy resistance in colon cancer.
abstract: OBJECTIVE
  KRAS mutations are frequent driver mutations in multiple cancers. KRAS mutations also induce anti-EGFR antibody resistance in adenocarcinoma such as colon cancer. The aim of this study was to overcome anti-EGFR antibody resistance by coupling the antibody to KRAS-specific siRNA.
  
  
  METHODS
  The anti-EGFR antibody was chemically coupled to siRNA. The resulting complex was tested for antibody binding efficiency, serum stability and ability to deliver siRNA to EGFR-expressing cells. Western blotting, viability, apoptosis, and colony formation assays were performed for efficacy evaluation in vitro. Furthermore, therapeutic activity of the antibody-KRAS-siRNA complexes was examined in in vivo xenograft mouse tumor models.
  
  
  RESULTS
  Antibody-siRNA complexes were targeted and internalized via the EGFR receptor. Upon internalization, target gene expression was strongly and specifically repressed, followed by a reduced proliferation and viability, and induced apoptosis of the cells in vitro. Clonogenic growth of mutant KRAS-bearing cells was suppressed by KRAS-siRNA-anti-EGFR antibody complexes. In xenograft mouse models, anti-EGFR antibody-KRAS-siRNA complexes significantly slowed tumor growth in anti-EGFR-resistant cells.
  
  
  CONCLUSIONS
  The coupling of siRNA against KRAS to anti-EGFR antibodies provides a novel therapy approach for KRAS-mutated EGFR-positive cancer cells in vitro and in vivo. These findings provide an innovative approach for cancer-specific siRNA application and for enhanced therapeutic potential of monoclonal antibody therapy and personalized treatment of cancer entities.
authors.affiliation: Department of Medicine A, Hematology/Oncology, University of Muenster, Muenster, Germany. baumers@uni-muenster.de Carsten.mueller-tidow@uk-halle.de.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Bäumer
authors.affiliation: Department of Medicine A, Hematology/Oncology, University of Muenster, Muenster, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Bäumer
authors.affiliation: Department of Medicine A, Hematology/Oncology, University of Muenster, Muenster, Germany.
authors.forename: Neele
authors.initials: N
authors.lastname: Appel
authors.affiliation: Department of Medicine A, Hematology/Oncology, University of Muenster, Muenster, Germany.
authors.forename: Lisa
authors.initials: L
authors.lastname: Terheyden
authors.affiliation: Department of Medicine A, Hematology/Oncology, University of Muenster, Muenster, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Fremerey
authors.affiliation: European Institute for Molecular Imaging (EIMI), University of Muenster, Muenster, Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Schelhaas
authors.affiliation: Gerhard-Domagk Institute for Pathology, University of Muenster, Muenster, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Wardelmann
authors.affiliation: UCC, Medical Systems Biology, Medical Faculty, TU Dresden, Dresden, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Buchholz
authors.affiliation: Department of Medicine A, Hematology/Oncology, University of Muenster, Muenster, Germany.
authors.forename: Wolfgang E
authors.initials: WE
authors.lastname: Berdel
authors.affiliation: Department of Medicine A, Hematology/Oncology, University of Muenster, Muenster, Germany. Department of Medicine IV, Hematology and Oncology, University of Halle, Halle, Germany. baumers@uni-muenster.de Carsten.mueller-tidow@uk-halle.de.
authors.forename: Carsten
authors.initials: C
authors.lastname: Müller-Tidow
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000235:genetics; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000627:therapeutic use*; D000970:Antineoplastic Agents / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D000068818:Cetuximab / Q000627:therapeutic use; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000276:immunology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D011479:Protamines / Q000627:therapeutic use; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics* / Q000276:immunology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000627:therapeutic use*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D011479:Protamines; D034741:RNA, Small Interfering; C541485:EGFR protein, mouse; D066246:ErbB Receptors; C495971:Hras protein, mouse; D016283:Proto-Oncogene Proteins p21(ras); D000068818:Cetuximab