title: The role of the insulin-like growth factor system in colorectal cancer: review of current knowledge.
abstract: BACKGROUND
  The insulin-like growth factor system, which includes insulin-like growth factors (IGF-I and IGF-II), IGF receptors (IGF-IR and IGF-IIR) and IGF binding proteins (IGFBPs), plays an important role in epithelial growth, anti-apoptosis and mitogenesis. There is a growing body of evidence showing that IGFs control growth and proliferation of several types of cancer. This review introduces the latest information on the biology of the IGF system and its pathophysiological role in the development of colorectal cancer.
  
  
  CONCLUSIONS
  The growth promoting effects of IGF-I and IGF-II on cancer cells are mediated through the IGF-IR, which is a tyrosine kinase and cancer cells with a strong tendency to metastasise have a higher expression of the IGF-IR. Most of the IGFs in circulation are bound to the IGFBPs, which regulate the bioavailability of the IGFs. All IGFBPs inhibit IGF action by high affinity binding, while some of them also potentiate the effects of IGFs. Colon cancer cells produce specific proteases that degrade the IGFBP so that the IGF will be free to act on the cancer cell in an autocrine manner. Therefore, the IGFBPs play a crucial role in the development of the cancer.
  
  
  CONCLUSIONS
  The current knowledge about the link between IGFs and colon cancer is mainly based on in vitro investigations. Further in vivo study is needed to understand the exact role of the IGF system, especially its binding proteins, so that they can be manipulated for the prevention and treatment of colorectal cancer.
authors.affiliation: University Department of Surgery, Royal Free and University College Medical School, University College London, Rowland Hill Street, London, NW3 2PF, UK.
authors.forename: Rajaraman
authors.initials: R
authors.lastname: Durai
authors.forename: Wenxuan
authors.initials: W
authors.lastname: Yang
authors.forename: Sharmila
authors.initials: S
authors.lastname: Gupta
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Seifalian
authors.forename: Marc C
authors.initials: MC
authors.lastname: Winslet
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D014408:Biomarkers, Tumor / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D013002:Somatomedins / Q000502:physiology*
chemical_list: D014408:Biomarkers, Tumor; D013002:Somatomedins