Insulin-like growth factor-II overexpression in MCF-7 cells induces phenotypic changes associated with malignant progression

Mol Endocrinol. 1992 Jan;6(1):91-100. doi: 10.1210/mend.6.1.1310798.

Abstract

It has been proposed that the insulin-like growth factors (IGFs) can act as autocrine and/or paracrine growth promoters in breast cancer. To investigate this hypothesis, we infected early passage MCF-7 cells with a retroviral vector containing the coding sequence for the IGF-II preprohormone along with a constitutive cytomegalovirus promoter sequence. These cells do not normally express IGF-I or IGF-II. After infection with the retroviral vector, several single cell clones were analyzed. Seven of nine isolated clones expressed very high levels of IGF-II mRNA. Biologically active IGF-II protein was easily detectable in the medium conditioned by the IGF-II-expressing clones, and IGF receptors were down-regulated in these. All IGF-II-expressing clones showed marked morphological changes in anchorage-dependent culture, growing in large clumps and as free-floating colonies. The cells also cloned in soft agar in the absence of estrogen, while the wild-type MCF-7 cells and control cells infected with an irrelevant DNA sequence showed none of these properties. alpha IR-3, an antibody that blocks the type I IGF receptor, inhibited the growth of IGF-II-expressing clones in serum-free medium. This model demonstrates that IGF-II can serve as an autocrine growth stimulant in breast cancer epithelial cells and that IGF-II overexpression may be capable of mediating malignant progression in human breast cancer.

MeSH terms

  • Breast Neoplasms / physiopathology
  • Cell Adhesion / physiology
  • Cell Division / physiology
  • Cell Transformation, Neoplastic*
  • Estrogens / physiology
  • Female
  • Genetic Vectors / genetics
  • Humans
  • Insulin-Like Growth Factor II / biosynthesis*
  • Insulin-Like Growth Factor II / genetics
  • Insulin-Like Growth Factor II / physiology
  • Phenotype
  • RNA, Messenger / analysis
  • RNA, Messenger / genetics*
  • Receptors, Cell Surface / physiology
  • Receptors, Somatomedin
  • Retroviridae / genetics
  • Transfection / genetics
  • Tumor Cells, Cultured

Substances

  • Estrogens
  • RNA, Messenger
  • Receptors, Cell Surface
  • Receptors, Somatomedin
  • Insulin-Like Growth Factor II