Prolactin overexpression by MDA-MB-435 human breast cancer cells accelerates tumor growth

Breast Cancer Res Treat. 2003 May;79(2):241-52. doi: 10.1023/a:1023956223037.


Prolactin (PRL) is an important hormone in mammary tumorigenesis in rodents but its involvement in human breast cancer has been controversial. A role for locally produced PRL in breast carcinogenesis is suggested by its mitogenic action on breast cancer cells and the expression of both PRL and its receptor (PRL-R) in breast carcinomas. Our objective was to examine whether PRL, overexpressed by breast cancer cells, forms an autocrine/paracrine loop that confers a growth advantage for tumors. MDA-MB-435 breast cancer cells overexpressing 23K human PRL were generated, and PRL production and secretion by the clones were confirmed by RT-PCR, western blotting, and the Nb2 bioassay; control clones contain vector only. In vitro the 23K PRL clones proliferated faster and expressed higher levels of the PRL-R protein than controls only when incubated in charcoal-stripped serum (CSS) devoid of lactogenic hormones. When injected into the mammary fatpad of female nude mice or subcutaneously into males, the PRL-overexpressing clones formed tumors that grew 2-4-fold faster than tumors derived from control clones or wild type MDA-MB-435 cells. Western analysis demonstrated significantly higher PRL, PRL-R, and bcl-2 levels in the tumors overexpressing PRL compared to control tumors. These data support a role for breast PRL as a growth/anti-apoptotic factor and suggest that it may serve as a novel therapeutic target for the treatment of breast cancer.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology*
  • Cell Division
  • Feedback, Physiological*
  • Female
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Lymphatic Metastasis
  • Mice
  • Mice, Nude
  • Neoplasm Transplantation
  • Prolactin / physiology*
  • RNA, Messenger / analysis
  • Receptors, Prolactin / metabolism
  • Tumor Cells, Cultured


  • RNA, Messenger
  • Receptors, Prolactin
  • Prolactin