title: Stimulation of colorectal cancer cell line growth by ET-1 and its inhibition by ET(A) antagonists.
abstract: BACKGROUND
  The vasoactive peptide endothelin 1 (ET-1) acts via two receptors, endothelin receptors A (ET(A)) and B (ET(B)). ET-1 is overexpressed by human cancers in vivo and in vitro and may be mitogenic for cancer cells.
  
  
  METHODS
  To elucidate if ET-1 is a growth regulator the following were investigated in human colorectal cancer cell lines (LIM1215 and HT29): ET-1 production by ELISA; ET receptor expression using radioligand autoradiographic techniques; and responsiveness to ET-1, and to ET(A) and ET(B) antagonism by growth measurements.
  
  
  RESULTS
  ET-1 was produced by LIM1215 and HT29 cells (21.3 and 41.7 fmol/ml/10(6) cells (24 hours); 22.6 and 71.7 fmol/ml/10(6) cells (48 hours), respectively). ET(A) and ET(B) receptors were expressed by both cell lines. Addition of ET-1 resulted in a dose dependent increase in cell numbers which was significant at 10(-8)-10(-9) M for LIM1215, with the greatest increase at 10(-8) M (32.7% and 28.4% increase above controls at 48 hours and 72 hours; p<0.05) and at 10(-8)-10(-9) M for HT29, with the greatest increase at 10(-9) M (13.4% and 15.7% increase above controls at 48 hours and 72 hours; p<0.05). ET(A) antagonists BQ123 and BQ610, but not the ET(B) antagonist BQ788, inhibited ET-1 induced proliferation of both LIM1215 and HT29 (p<0.05).
  
  
  CONCLUSIONS
  ET-1 can stimulate the proliferation of colorectal cancer cell lines via the ET(A), but not the ET(B), receptor.
authors.affiliation: Department of Surgery, Royal Free and University College Medical School, London, UK.
authors.forename: H
authors.initials: H
authors.lastname: Ali
authors.forename: M
authors.initials: M
authors.lastname: Loizidou
authors.forename: M
authors.initials: M
authors.lastname: Dashwood
authors.forename: F
authors.initials: F
authors.lastname: Savage
authors.forename: C
authors.initials: C
authors.lastname: Sheard
authors.forename: I
authors.initials: I
authors.lastname: Taylor
mesh_terms: D002455:Cell Division / Q000502:physiology; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology*; D019332:Endothelin-1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D019073:HT29 Cells / Q000187:drug effects; D006801:Humans; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000502:physiology*; D011869:Radioligand Assay; D017466:Receptors, Endothelin / Q000032:analysis; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D019332:Endothelin-1; D009363:Neoplasm Proteins; D017466:Receptors, Endothelin