title: Leptin-signaling inhibition results in efficient anti-tumor activity in estrogen receptor positive or negative breast cancer.
abstract: BACKGROUND
  We have shown previously that treatment with pegylated leptin peptide receptor antagonist 2 (PEG-LPrA2) reduced the expression of vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor type 2 (VEGFR2) and growth of 4T1-breast cancer (BC) in syngeneic mice. In this investigation, PEG-LPrA2 was used to evaluate whether the inhibition of leptin signaling has differential impact on the expression of pro-angiogenic and pro-proliferative molecules and growth of human estrogen receptor-positive (ER+) and estrogen receptor-negative (ER-) BC xenografts hosted by immunodeficient mice.
  
  
  METHODS
  To test the contribution of leptin signaling to BC growth and expression of leptin-targeted molecules, PEG-LPrA2 treatment was applied to severe immunodeficient mice hosting established ER+ (MCF-7 cells; ovariectomized/supplemented with estradiol) and ER- (MDA-MB231 cells) BC xenografts. To further assess leptin and PEG-LPrA2 effects on ER+ and ER- BC, the expression of VEGF and VEGFR2 (protein and mRNA) was investigated in cell cultures.
  
  
  RESULTS
  PEG-LPrA2 more effectively reduced the growth of ER+ (>40-fold) than ER- BC (twofold) and expression of pro-angiogenic (VEGF/VEGFR2, leptin/leptin receptor OB-R, and IL-1 receptor type I) and pro-proliferative molecules (proliferating cell nuclear antigen and cyclin D1) in ER+ than in ER- BC. Mouse tumor stroma in ER+ BC expressed high levels of VEGF and leptin that was induced by leptin signaling. Leptin upregulated the transcriptional expression of VEGF/VEGFR2 in MCF-7 and MDA-MB231 cells.
  
  
  CONCLUSIONS
  These results suggest that leptin signaling plays an important role in the growth of both ER+ and ER- BC that is associated with the leptin regulation of pro-angiogenic and pro-proliferative molecules. These data provide support for the potential use of leptin-signaling inhibition as a novel treatment for ER+ and ER- BC.
authors.affiliation: Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, Atlanta, GA 30310, USA. rgonzalez@msm.edu
authors.forename: Ruben
authors.initials: R
authors.lastname: Rene Gonzalez
authors.forename: Amber
authors.initials: A
authors.lastname: Watters
authors.forename: Yanbo
authors.initials: Y
authors.lastname: Xu
authors.forename: Udai P
authors.initials: UP
authors.lastname: Singh
authors.forename: David R
authors.initials: DR
authors.lastname: Mann
authors.forename: Bo R
authors.initials: BR
authors.lastname: Rueda
authors.forename: Manuel L
authors.initials: ML
authors.lastname: Penichet
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D020738:Leptin / Q000737:chemistry / Q000378:metabolism*; D008325:Mammary Neoplasms, Experimental / Q000188:drug therapy; D051379:Mice; D016513:Mice, SCID; D009368:Neoplasm Transplantation; D011092:Polyethylene Glycols / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
chemical_list: D000970:Antineoplastic Agents; D020738:Leptin; D011960:Receptors, Estrogen; D011092:Polyethylene Glycols