title: Leptin as a potential target for estrogen receptor-positive breast cancer.
abstract: OBJECTIVE
  Leptin is a potent adipokine that plays a significant role in tumor development and the progression of breast cancer. The aim of this study was to evaluate whether leptin affects the response to tamoxifen treatment in estrogen receptor (ER)-positive breast cancer cells.
  
  
  METHODS
  Leptin, leptin receptor (Ob-R), and activation of signaling pathways were studied by Western immunoblotting. The effects of leptin on tamoxifen-dependent growth inhibition were studied in MCF-7 and T-47D cells.
  
  
  RESULTS
  Leptin was expressed in MCF-7 and T-47D and had a proliferative effect on MCF-7 cells. Leptin significantly inhibited the antiestrogenic effect of tamoxifen in both cells only under β-estradiol (E2) (20 nM) conditions. In MCF-7, the inhibitory effect against tamoxifen was a result from the activation of the ERK1/2 and STAT3 signal transduction pathway.
  
  
  CONCLUSIONS
  Leptin interferes with the effects of tamoxifen under E2 stimulated conditions in ER-positive breast cancer cells. These results imply that inhibition of leptin is expected to enhance the response to tamoxifen in ER-positive breast cancer cells, and, therefore, could be a promising way to overcome endocrine resistance.
authors.affiliation: Department of Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
authors.forename: Cha Kyong
authors.initials: CK
authors.lastname: Yom
authors.forename: Kyung-Min
authors.initials: KM
authors.lastname: Lee
authors.forename: Wonshik
authors.initials: W
authors.lastname: Han
authors.forename: Sung-Won
authors.initials: SW
authors.lastname: Kim
authors.forename: Hee Sung
authors.initials: HS
authors.lastname: Kim
authors.forename: Byung In
authors.initials: BI
authors.lastname: Moon
authors.forename: Ku-Young
authors.initials: KY
authors.lastname: Jeong
authors.forename: Seock-Ah
authors.initials: SA
authors.lastname: Im
authors.forename: Dong-Young
authors.initials: DY
authors.lastname: Noh
keywords: Breast neoplasms; Hormone resistance; Leptin