title: Ghrelin and obestatin in thyroid gland - immunohistochemical expression in nodular goiter, papillary and medullary cancer.
abstract: BACKGROUND
  Previous studies analyzing ghrelin and obestatin expression in thyroid gland tissue are not unanimous and are mostly related to ghrelin. The role of ghrelin and obestatin in the thyroid gland appears very interesting due to their probable involvement in cell proliferation. Furthermore, since the thyroid gland is associated with the maintenance of energy balance, the relationship between ghrelin, obestatin and thyroid function is worthy of consideration. The aim of the study was to assess ghrelin and obestatin immunocytochemical expression in nodular goiter (NG), papillary cancer (PTC) and medullary cancer (MTC).
  
  
  METHODS
  Analyzed samples included 9 cases of NG, 8 cases of PTC and 11 cases of MTC. The analysis of ghrelin and obestatin expression was performed by use of the immunohistochemical (IHC) EnVision system and evaluated with filter HSV software (quantitative morphometric analysis).
  
  
  RESULTS
  Quantitative ghrelin expression in MTC cells was higher than in NG (p = 0.013) and correlated negatively with the size of the tumor (r= -0.829, p < 0.05). We did not observe any differences in ghrelin expression neither between MTC and PTC nor between NG and PTC. Obestatin immunoexpression pattern in all analyzed specimens was irregular and poorly accented. The strongest immunoreactivity for obestatin was demonstrated in NG. In MTC obestatin expression was significantly weaker than in NG and PTC (p < 0.05 in both cases). In NG the intensity of obestatin immunostaining was significantly higher than that of ghrelin (p = 0.03). Conversely, ghrelin expression in MTC was definitely more evident than obestatin immunoreactivity (p < 0.01). There was no statistically significant difference between ghrelin and obestatin expression in PTC. No correlations were detected between reciprocal tissue expressions of ghrelin and obestatin in the analyzed specimens of NG, PTC or MTC.
  
  
  CONCLUSIONS
  The differences between ghrelin expression in NG and MTC suggest that ghrelin may be involved in thyroid cell proliferation. The differences between ghrelin and obestatin immunoreactivity in benign and malignant thyroid tumors could support the theory of alternative transcription of the preproghrelin gene and independent production of ghrelin and obestatin.
authors.affiliation: Department of Endocrinology, Metabolism and Internal Medicine, Poznan University of Medical Sciences, Poznan, Poland. liberius@interia.pl.
authors.forename: Edyta
authors.initials: E
authors.lastname: Gurgul
authors.forename: Aldona
authors.initials: A
authors.lastname: Kasprzak
authors.forename: Agata
authors.initials: A
authors.lastname: Blaszczyk
authors.forename: Maciej
authors.initials: M
authors.lastname: Biczysko
authors.forename: Joanna
authors.initials: J
authors.lastname: Surdyk-Zasada
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Seraszek-Jaros
authors.forename: Marek
authors.initials: M
authors.lastname: Ruchala
mesh_terms: D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000378:metabolism* / Q000473:pathology; D018278:Carcinoma, Neuroendocrine / Q000378:metabolism* / Q000473:pathology; D002291:Carcinoma, Papillary; D005260:Female; D054439:Ghrelin / Q000235:genetics / Q000378:metabolism*; D006044:Goiter, Nodular / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D000077273:Thyroid Cancer, Papillary; D013961:Thyroid Gland / Q000378:metabolism* / Q000473:pathology; D013964:Thyroid Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D054439:Ghrelin