title: Inhibition of mouse melanoma cell proliferation by corticotropin-releasing hormone and its analogs.
abstract: BACKGROUND
  Observations that epidermal cells release both corticotropin-releasing hormone (CRH) and proopiome lanocortin (POMC) peptides has raised questions about the physiological relevance of this hypothalamo-pituitary-like system in mammalian skin. As CRH has shown anti-proliferative effects on cultured keratinocytes, we tested whether CRH can also regulate growth of melanoma cells.
  
  
  METHODS
  CRH, [D-Glu20]-CRH, [D-Pro5]-CRH, acetyl-cyclo(30-33)[D-Phe12,D-Glu20,Nle21,D-His32,Lys33,D-Nle38]-CRH(4-41), acetyl-cyclo(30-33)[D-Phe12,Nle18,D-Glu20,Nle21,D-Ala32]-urotensin I(4-41), urocortin, and sauvagine were tested on Cloudman melanoma cell proliferation in culture and B16 melanoma tumor growth in C57B1/6 mice. Calcium-sensitive fluorescence measurements were used to examine the effect of CRH on intracellular Ca2+ signaling. The effects of CRH and [D-Glu20]-CRH on blood pressure were compared by measuring mean arterial pressure in anesthetized rats.
  
  
  RESULTS
  CRH and six analogs were tested, and all demonstrated exceptional potency in inhibiting Cloudman cell proliferation in culture, with half-maximal effective concentrations ranging between 0.2 and 100 pM. The amplitude of ionomycin-induced Ca2+ influx into Cloudman cells grown in suspension was reduced by 50% after 48-hr exposure to CRH. Daily injections of CRH or [D-Glu20]-CRH, 100 micrograms/kg.day s.c., for 5 days, reduced net B16 tumor volume in mice by 30-60% compared to control animals. [D-Glu20]-CRH was less hypotensive compared to CRH, despite having similar anti-proliferative potency.
  
  
  CONCLUSIONS
  CRH, and various analogs thereof, inhibit proliferation of Cloudman cells in culture, and inhibit B16 tumor growth rate in vivo, most likely by activation of endogenous CRH1 receptors and subsequent altered intracellular Ca2+ signaling. CRH analogs, such as [D-Glu20]-CRH, with less hypotensive activity may provide new directions of therapy for melanoma.
authors.affiliation: School of Public Health, University of California, Berkeley, California, USA.
authors.forename: K W
authors.initials: KW
authors.lastname: Carlson
authors.forename: S S
authors.initials: SS
authors.lastname: Nawy
authors.forename: E T
authors.initials: ET
authors.lastname: Wei
authors.forename: W
authors.initials: W
authors.lastname: Sadée
authors.forename: V A
authors.initials: VA
authors.lastname: Filov
authors.forename: V V
authors.initials: VV
authors.lastname: Rezsova
authors.forename: A
authors.initials: A
authors.lastname: Slominski
authors.forename: J M
authors.initials: JM
authors.lastname: Quillan
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D002413:Cations, Divalent; D002455:Cell Division; D003346:Corticotropin-Releasing Hormone / Q000031:analogs & derivatives / Q000378:metabolism / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006131:Growth Inhibitors / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use*; D007424:Intracellular Fluid / Q000378:metabolism; D008545:Melanoma; D008546:Melanoma, Experimental / Q000188:drug therapy* / Q000503:physiopathology; D051379:Mice; D008810:Mice, Inbred C57BL; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology; D018019:Receptors, Corticotropin-Releasing Hormone / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D002413:Cations, Divalent; D006131:Growth Inhibitors; D010455:Peptides; D018019:Receptors, Corticotropin-Releasing Hormone; D003346:Corticotropin-Releasing Hormone; D002118:Calcium