title: Inhibition of Cdc42-interacting protein 4 (CIP4) impairs osteosarcoma tumor progression.
abstract: BACKGROUND
  In patients with Osteosarcoma (OS), larger primary tumor size correlates with higher metastasis incidence and lower overall survival. Identifying the mechanisms that control primary tumor growth can lead to the new therapeutic approaches and improve prognosis. Cytoskeleton regulatory molecules play an important role in tumor cells proliferation and motility. In the current study, we investigated the role of scaffolding protein Cdc42-interacting protein 4 (CIP4) in OS.
  
  
  METHODS
  Murine OS cells, DLM8 were stably transfected with shCIP4 plasmid and their tumorigenic activity was studied in vitro and in vivo. The effect of CIP4 downregulation on cytoskeleton was studied by immunohistochemical analysis.
  
  
  RESULTS
  In vivo studies revealed that downregulation of CIP4 in OS tumor cells can inhibit primary subcutaneous tumor growth and delay spontaneous metastases growth in the animal lungs. In vitro studies confirmed that inhibiting CIP4 expression significantly reduced tumor cells invasiveness and migration. Changes in CIP4 expression altered its cellular localization pattern and tumor cell morphology, which could explain changes in OS cell behavior in vivo and in vitro. Cells with downregulated CIP4 showed lower levels of actin in cells along with fewer perinuclear actin stress filaments and actin bridges to the lipid bilayer of the cell membrane than control cells.
  
  
  CONCLUSIONS
  This study presents compelling evidence that inhibition of CIP4 expression in OS cells impairs metastatic behavior of cells in vitro and prolongs survival of animals by inhibiting primary tumor growth. Although the lack of CIP4 in tumor cells did not prevent formation of metastasis, it did substantially delay their formation in the animals' lungs.
authors.affiliation: Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. nvkoshki@mdanderson.org
authors.forename: Nadezhda V
authors.initials: NV
authors.lastname: Koshkina
authors.forename: Ge
authors.initials: G
authors.lastname: Yang
authors.forename: Eugenie S
authors.initials: ES
authors.lastname: Kleinerman
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D002465:Cell Movement; D015536:Down-Regulation; D005260:Female; D020868:Gene Silencing; D008168:Lung / Q000378:metabolism* / Q000473:pathology; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control* / Q000556:secondary; D051379:Mice; D008809:Mice, Inbred C3H; D008869:Microtubule-Associated Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015778:Minor Histocompatibility Antigens; D009361:Neoplasm Invasiveness; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D009368:Neoplasm Transplantation; D012516:Osteosarcoma / Q000378:metabolism / Q000473:pathology / Q000556:secondary / Q000628:therapy*; D021381:Protein Transport; D034741:RNA, Small Interfering; D016019:Survival Analysis
chemical_list: D000199:Actins; D008869:Microtubule-Associated Proteins; D015778:Minor Histocompatibility Antigens; D009363:Neoplasm Proteins; D034741:RNA, Small Interfering; C485787:Trip10 protein, mouse