title: Inhibition of Six1 affects tumour invasion and the expression of cancer stem cell markers in pancreatic cancer.
abstract: Epithelial-to-mesenchymal transition (EMT) and cancer stem cells (CSC) contribute to tumour progression and metastasis. Assessment of transcription factors involved in these two mechanisms can help to identify new targets for an oncological therapy. In this study, we focused on the evaluation of the transcription factor Six1 (Sine oculis 1). This protein is involved in embryologic development and its contribution to carcinogenesis has been described in several studies.
  
  
  
  Immunohistochemistry against Six1 was performed on a tissue microarray containing specimens of primary pancreatic ductal adenocarcinomas (PDAC) of 139 patients. Nuclear and cytoplasmic expression was evaluated and correlated to histopathological parameters. Expression of Six1 was inhibited transiently by siRNA in Panc1 and BxPc3 cells and stably by shRNA in Panc1 cells. Expression analysis of CDH1 and Vimentin mRNA was performed and cell motility was tested in a migration assay. Panc1 cells transfected with Six1 shRNA or scrambled shRNA were injected subcutaneously into nude mice. Tumour growth was observed for four weeks. Afterwards, tumours were stained against Six1, CD24 and CD44.
  
  
  
  Six1 was overexpressed in the cytoplasm and cellular nuclei in malignant tissues (p < 0.0001). No correlation to histopathological parameters could be detected. Six1 down-regulation decreased pancreatic cancer cell motility in vitro. CDH1 and vimentin expression was decreased after inhibition of the expression of Six1. Pancreatic tumours with impaired expression of Six1 showed significantly delayed growth and displayed loss of the CD24+/CD44+phenotype.
  
  
  
  We show that Six1 is overexpressed in human PDAC and that its inhibition results in a decreased tumour progression in vitro and in vivo. Therefore, targeting Six1 might be a novel therapeutic approach in patients with pancreatic cancer.
authors.affiliation: Department of General, Visceral and Transplantation Surgery, Im Neuenheimer Feld 110, 69120, Heidelberg, Germany.
authors.forename: Tristan
authors.initials: T
authors.lastname: Lerbs
authors.affiliation: Department of Internal Medicine 3, Center of Integrated Oncology (CIO) Cologne-Bonn, University Hospital of Bonn, Bonn, Germany.
authors.forename: Savita
authors.initials: S
authors.lastname: Bisht
authors.affiliation: Department of Gastrointestinal, Thoracic and Vascular Surgery, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, 01307, Dresden, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Schölch
authors.affiliation: Department of Gastrointestinal, Thoracic and Vascular Surgery, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, 01307, Dresden, Germany.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Pecqueux
authors.affiliation: Department of Pathology, Center of Integrated Oncology Cologne-Bonn, University Hospital of Bonn, Bonn, Germany.
authors.forename: Glen
authors.initials: G
authors.lastname: Kristiansen
authors.affiliation: Department of General, Visceral and Transplantation Surgery, Im Neuenheimer Feld 110, 69120, Heidelberg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schneider
authors.affiliation: Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany.
authors.forename: Bianca T
authors.initials: BT
authors.lastname: Hofmann
authors.affiliation: Department of Gastrointestinal, Thoracic and Vascular Surgery, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, 01307, Dresden, Germany.
authors.forename: Thilo
authors.initials: T
authors.lastname: Welsch
authors.affiliation: Department of Gastrointestinal, Thoracic and Vascular Surgery, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, 01307, Dresden, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Reissfelder
authors.affiliation: Department of Gastrointestinal, Thoracic and Vascular Surgery, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, 01307, Dresden, Germany.
authors.forename: Nuh N
authors.initials: NN
authors.lastname: Rahbari
authors.affiliation: Department of Gastrointestinal, Thoracic and Vascular Surgery, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, 01307, Dresden, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Fritzmann
authors.affiliation: Department of Internal Medicine 3, Center of Integrated Oncology (CIO) Cologne-Bonn, University Hospital of Bonn, Bonn, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Brossart
authors.affiliation: Department of Gastrointestinal, Thoracic and Vascular Surgery, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, 01307, Dresden, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Weitz
authors.affiliation: Department of Internal Medicine 3, Center of Integrated Oncology (CIO) Cologne-Bonn, University Hospital of Bonn, Bonn, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Feldmann
authors.affiliation: Department of General, Visceral and Transplantation Surgery, Im Neuenheimer Feld 110, 69120, Heidelberg, Germany. christoph.kahlert.079@googlemail.com.|Department of Gastrointestinal, Thoracic and Vascular Surgery, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, 01307, Dresden, Germany. christoph.kahlert.079@googlemail.com.
authors.forename: Christoph
authors.initials: C
authors.lastname: Kahlert
mesh_terms: D000818:Animals; D058750:Epithelial-Mesenchymal Transition; D015972:Gene Expression Regulation, Neoplastic; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D014411:Neoplastic Stem Cells / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D034622:RNA Interference; D023041:Xenograft Model Antitumor Assays
chemical_list: D018398:Homeodomain Proteins; C099236:SIX1 protein, human
keywords: Cancer stem cells; Epithelial-mesenchymal transition; Pancreatic cancer; Six1