title: The Effects of Insulin-like Growth Factor-I (IGF-I) in Mouse Lung Cancer Cells.
abstract: OBJECTIVE
  Insulin-like growth factor-I (IGF-I) is an important mitogen in many types of malignancies. The purpose of this study was to evaluate the role of the IGF system on cell proliferation and cell death in mouse lung cancer cell lines (3LL).
  
  
  METHODS
  Northern analysis was performed in 3LL cells. We evaluated the phosphorylation of IGF-I receptor (IGF-IR) with IGF-I stimulation. MTT assay was performed after treating 3LL cells with IGF-I and the treatment effect on cell death in the presence of anticancer drug was investigated.
  
  
  RESULTS
  Northern analysis revealed the presence of IGF-I and IGF-IR mRNA expression in 3LL cells. IGF-I increased cellular proliferation in serum free media. IGF-I also stimulated the tyrosine phosphorylation of two proteins: one, with a molecular mass of 95 kDa, was the beta-subunit of IGF-IR; the other, with an approximate molecular mass of 185 kDa, was originally identified as the insulin receptor substrate-I (IRS-I). IGF-I at a low concentration inhibited the cell death induced by adriamycin.
  
  
  CONCLUSIONS
  IGF-I, a mitogen through the phosphorylation of the IGF-IR beta-subunit, acts as a survival factor to inhibit cell death. Therefore, these findings suggest that IGF-I and IGF-IR are involved in both the cell proliferation and cell death associated with cancer cell growth.
authors.forename: Seung Min
authors.initials: SM
authors.lastname: Kwak
authors.forename: Se Kyu
authors.initials: SK
authors.lastname: Kim
authors.forename: Sung Kyu
authors.initials: SK
authors.lastname: Kim
authors.forename: Chul Ho
authors.initials: CH
authors.lastname: Cho
keywords: Cell death; Cell proliferation; IGF-I receptor (IGF-IR); Insulin-like growth factor-I (IGF-I); Survival factor