title: Combining the multitargeted tyrosine kinase inhibitor vandetanib with the antiestrogen fulvestrant enhances its antitumor effect in non-small cell lung cancer.
abstract: BACKGROUND
  Estrogen is known to promote proliferation and to activate the epidermal growth factor receptor (EGFR) in non-small cell lung cancer (NSCLC). Vascular endothelial growth factor (VEGF) is a known estrogen responsive gene in breast cancer. We sought to determine whether the VEGF pathway is also regulated by estrogen in lung cancer cells, and whether combining an inhibitor of the ER pathway with a dual vascular endothelial growth factor receptor (VEGFR)/EGFR inhibitor would show enhanced antitumor effects.
  
  
  METHODS
  We examined activation of EGFR and expression of VEGF in response to β-estradiol, and the antitumor activity of the multitargeted VEGFR/EGFR/RET inhibitor, vandetanib, when combined with the antiestrogen fulvestrant both in vitro and in vivo.
  
  
  RESULTS
  NSCLC cells expressed VEGFR-3 and EGFR. Vandetanib treatment of NSCLC cells resulted in inhibition of EGFR and VEGFR-3 and inhibition of β-estradiol-induced P-MAPK activation, demonstrating that vandetanib blocks β-estradiol-induced EGFR signaling. Treatment with β-estradiol stimulated VEGFA mRNA and protein (p < 0.0001 over baseline), suggesting estrogenic signaling causes heightened VEGFA pathway activation. This estrogenic induction of VEGFA mRNA seems largely dependent on cross-talk with EGFR. Long-term vandetanib treatment also significantly increased ERβ protein expression. The combination of vandetanib with fulvestrant maximally inhibited cell growth compared with single agents (p < 0.0001) and decreased tumor xenograft volume by 64%, compared with 51% for vandetanib (p < 0.05) and 23% for fulvestrant (p < 0.005). Antitumor effects of combination therapy were accompanied by a significant increase in apoptotic cells compared with single agents.
  
  
  CONCLUSIONS
  Fulvestrant may enhance effects of vandetanib in NSCLC by blocking estrogen-driven activation of the EGFR pathway.
authors.affiliation: Department of Pharmacology & Chemical Biology, University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Jill M
authors.initials: JM
authors.lastname: Siegfried
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Gubish
authors.forename: Mary E
authors.initials: ME
authors.lastname: Rothstein
authors.forename: Cassandra
authors.initials: C
authors.lastname: Henry
authors.forename: Laura P
authors.initials: LP
authors.lastname: Stabile
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D049109:Cell Proliferation / Q000187:drug effects; D004357:Drug Synergism; D004797:Enzyme-Linked Immunosorbent Assay; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D020847:Estrogen Receptor Modulators / Q000494:pharmacology*; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D005455:Fluorescent Antibody Technique; D000077267:Fulvestrant; D006801:Humans; D007124:Immunoenzyme Techniques; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D051379:Mice; D016513:Mice, SCID; D010880:Piperidines / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011799:Quinazolines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
chemical_list: D020847:Estrogen Receptor Modulators; D004967:Estrogens; D010880:Piperidines; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D000077267:Fulvestrant; D004958:Estradiol; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D040321:Vascular Endothelial Growth Factor Receptor-3; C452423:vandetanib