title: Leptin promotes melanoma tumor growth in mice related to increasing circulating endothelial progenitor cells numbers and plasma NO production.
abstract: BACKGROUND
  Epidemiological studies propose that obesity increases the risk of several cancers, including melanoma. Obesity increases the expression of leptin, a multifunctional peptide produced predominantly by adipocytes which may promote tumor growth. Several recently experiments have suggested that the tumors growth is in need of endothelial progenitor cell (EPC) dependent generation of new blood vessels.Our objectives in the present study were to examine the effects of leptin on melanoma growth, circulating EPCs number and plasma levels of nitric oxide metabolites (NOx).
  
  
  METHODS
  2 × 106 B16F10 melanoma cells were injected to thirty two C57BL6 mice subcutaneously. The mice were randomly divided into 4 groups (n = 8) in 8th day. Two groups were received twice daily intraperitoneal(i.p) injections of either PBS or recombinant murine leptin (1 μg/g initial body weight). Two groups were received i.p. injections of either 9F8 an anti leptin receptor antibody or the control mouse IgG at 50 μg/mouse every 3 consecutive days. By the end of the second week the animals were euthanized and blood samples and tumors were analyzed.
  
  
  RESULTS
  The tumor weight, EPC numbers and NOx level in leptin, PBS, 9F8, and IgG group were (3.2 ± 0.6, 1.7 ± 0.3, 1.61 ± 0.2,1.7 ± 0.3 g), (222.66 ± 36.5, 133.33 ± 171, 23.33 ± 18, 132.66 ± 27.26/ml of blood), and (22.47 ± 5.5, 12.30 ± 1.5, 6.26 ± 0.84, 15.75 ± 6.3 μmol/L) respectively. Tumors weight and size, circulating EPC numbers and plasma levels of NOx were significantly more in the leptin than 9f8 and both control groups (p < 0.05). The plasma concentration of NOx significantly decreased in 9f8 treated mice compare to control group (p < 0.05).
  
  
  CONCLUSIONS
  In conclusion, our observations indicate that leptin causes melanoma growth likely through increased NO production and circulating EPC numbers and consequently vasculogenesis.
authors.affiliation: Applied Physiology Research Center and Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Fatemehsadat
authors.initials: F
authors.lastname: Amjadi
authors.forename: Shaghaygh Haghjooy
authors.initials: SH
authors.lastname: Javanmard
authors.forename: Hamid
authors.initials: H
authors.lastname: Zarkesh-Esfahani
authors.forename: Majid
authors.initials: M
authors.lastname: Khazaei
authors.forename: Manijeh
authors.initials: M
authors.lastname: Narimani
mesh_terms: D017667:Adipocytes / Q000378:metabolism; D000818:Animals; D042783:Endothelial Cells / Q000473:pathology*; D020738:Leptin / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D008546:Melanoma, Experimental / Q000097:blood / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000097:blood / Q000378:metabolism; D054411:Receptors, Leptin / Q000378:metabolism; D012878:Skin Neoplasms / Q000097:blood / Q000378:metabolism / Q000473:pathology*; D013234:Stem Cells / Q000473:pathology*
chemical_list: D020738:Leptin; D054411:Receptors, Leptin; D009569:Nitric Oxide