Differential regulation of c-myc by progestins and antiestrogens in T-47D human breast cancer cells

J Steroid Biochem Mol Biol. 1991 Jul;39(1):39-44. doi: 10.1016/0960-0760(91)90010-3.


In order to investigate further the mechanisms associated with growth inhibition of human breast cancer cells by progestins and nonsteroidal antiestrogens, their effect on c-myc gene expression in T-47D-5 and T-47D cells has been investigated. The c-myc mRNA levels were differentially regulated by the synthetic progestin, medroxyprogesterone acetate and the nonsteroidal antiestrogen, monohydroxytamoxifen, in both cell lines. Antiestrogen treatment caused a persistent decrease in c-myc mRNA levels while the progestin caused a more complex response. Initially c-myc mRNA levels increased approx. 2-fold, this was followed by a decrease and then partial recovery. The end result, however, of each of these treatments is decreased cell number.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breast Neoplasms / drug therapy
  • Breast Neoplasms / genetics*
  • Cell Line
  • Cell Transformation, Neoplastic / drug effects
  • Estrogen Antagonists / pharmacology*
  • Female
  • Gene Expression Regulation, Neoplastic / drug effects*
  • Genes, myc*
  • Humans
  • Medroxyprogesterone / analogs & derivatives
  • Medroxyprogesterone / pharmacology
  • Medroxyprogesterone Acetate
  • Progestins / pharmacology*
  • Proto-Oncogene Proteins c-myc / biosynthesis
  • Proto-Oncogene Proteins c-myc / genetics
  • RNA, Messenger / metabolism
  • Tamoxifen / analogs & derivatives
  • Tamoxifen / pharmacology
  • Tumor Cells, Cultured


  • Estrogen Antagonists
  • Progestins
  • Proto-Oncogene Proteins c-myc
  • RNA, Messenger
  • Tamoxifen
  • afimoxifene
  • Medroxyprogesterone Acetate
  • Medroxyprogesterone