title: Circulating insulin-like growth factor-I levels regulate colon cancer growth and metastasis.
abstract: It has been shown previously that slight elevations in serum levels of insulin-like growth factor-I (IGF-I) are correlated with an increased risk for developing prostate, breast, colon, and lung cancer. The aim of this study was to determine the role of serum IGF-I levels in the process of stimulating tumor growth and metastasis in a mouse model of colon cancer. Colon 38 adenocarcinoma tissue fragments were orthotopically transplanted by attachment to the surface of the cecum in control and liver-specific IGF-I-deficient (LID) mice in which serum IGF-I levels are 25% of that in control mice. A total of 156 male mice at 5 weeks of age (74 control mice and 82 LID mice) received tumor transplants. Mice were divided randomly into two groups; one group was injected i.p. with recombinant human IGF-I (2 mg/kg) twice daily for 6 weeks, and the other group received saline injections. IGF-I treatment increased the serum levels of IGF-I and IGFBP-3 in both control and LID mice. In the saline-injected group, the incidence of tumor growth on the cecum as well as the frequency of hepatic metastasis was significantly higher in control mice as compared with LID mice. Both control and LID mice treated with recombinant human IGF-I displayed significantly increased rates of tumor development on the cecum and metastasis to the liver, as compared with saline-injected mice. The number of metastatic nodules in the liver was significantly higher in control mice as compared with LID mice. The expression of vascular epithelial growth factor (VEGF) as well as vessel abundance in the cecum tumors was dependent on the levels of serum IGF-I. This study supports the hypothesis that circulating IGF-I levels play an important role in tumor development and metastasis.
authors.affiliation: Section of Cellular and Molecular Physiology, Cellular Endocrinology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland 20892-1758, USA.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Wu
authors.forename: Shoshana
authors.initials: S
authors.lastname: Yakar
authors.forename: Ling
authors.initials: L
authors.lastname: Zhao
authors.forename: Lothar
authors.initials: L
authors.lastname: Hennighausen
authors.forename: Derek
authors.initials: D
authors.lastname: LeRoith
mesh_terms: D000230:Adenocarcinoma / Q000145:classification / Q000473:pathology*; D000818:Animals; D002430:Cecal Neoplasms / Q000378:metabolism / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D003110:Colonic Neoplasms / Q000097:blood / Q000473:pathology*; D005260:Female; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D008114:Liver Neoplasms, Experimental / Q000378:metabolism / Q000556:secondary; D051379:Mice; D008810:Mice, Inbred C57BL; D017526:Receptor, IGF Type 1 / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1