title: Elevated peripheral blood plasma concentrations of tie-2 and angiopoietin 2 in patients with neuroendocrine tumors.
abstract: BACKGROUND
  Gastro-entero-pancreatic/neuroendocrine (NET) tumors are highly vascularized neoplasms. However, our knowledge concerning circulating levels of the angiogenic factors in NET patients still remains insufficient.
  
  
  METHODS
  The aim of this study was to measure plasma concentrations of VEGF, angiopoietin 1 (Ang-1), angiopoietin 2 (Ang-2), soluble Tie-2, endostatin, osteopontin (OPN) and chromogranin A (CgA) in 36 NET patients and 16 controls.
  
  
  RESULTS
  Only the plasma concentrations of Tie-2 and CgA were higher in NET patients as compared to controls. These levels were within the reference range in controls; however one control demonstrated slightly elevated Tie-2 and 4 elevated CgA. Similarly, in the subgroup of patients with carcinoid syndrome, only Tie-2 and CgA concentrations were higher than those in patients with non-functioning NETs. In turn, in the subgroup of metastatic patients, only Ang-2 levels were higher than in those with localized disease. A positive correlation was found between Ang-2 and Tie-2 levels in metastatic patients and between Ang-1 and Tie-2 in localized NETs.
  
  
  CONCLUSIONS
  The plasma concentration of Tie-2 is proposed as an additional marker for NET patients and seems to be similarly effective as the currently used CgA level. Moreover, higher plasma levels of Ang-2 together with the positive correlation between Ang-2 and Tie-2 levels in metastatic subjects, implies that cases with a Tie-2 level above the upper limits, together with higher level of Ang-2 seem to be highly predictive of metastases.
authors.affiliation: Department of Immunoendocrinology, Chair of Endocrinology, Medical University of Lodz, Dr Sterling Str. No. 3, 91-425 Lodz, Poland.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Melen-Mucha
authors.affiliation: Department of Immunoendocrinology, Chair of Endocrinology, Medical University of Lodz, Dr Sterling Str. No. 3, 91-425 Lodz, Poland.
authors.forename: Agata
authors.initials: A
authors.lastname: Niedziela
authors.affiliation: Department of Clinical Endocrinology, Chair of Endocrinology, Medical University of Lodz, Dr Sterling Str. No. 3, 91-425 Lodz, Poland.
authors.forename: Slawomir
authors.initials: S
authors.lastname: Mucha
authors.affiliation: Department of Immunoendocrinology, Chair of Endocrinology, Medical University of Lodz, Dr Sterling Str. No. 3, 91-425 Lodz, Poland.
authors.forename: Ewelina
authors.initials: E
authors.lastname: Motylewska
authors.affiliation: Department of Immunoendocrinology, Chair of Endocrinology, Medical University of Lodz, Dr Sterling Str. No. 3, 91-425 Lodz, Poland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Lawnicka
authors.affiliation: Department of Clinical Endocrinology, Chair of Endocrinology, Medical University of Lodz, Dr Sterling Str. No. 3, 91-425 Lodz, Poland.
authors.forename: Jan
authors.initials: J
authors.lastname: Komorowski
authors.affiliation: Department of Immunoendocrinology, Chair of Endocrinology, Medical University of Lodz, Dr Sterling Str. No. 3, 91-425 Lodz, Poland.
authors.forename: Henryk
authors.initials: H
authors.lastname: Stepien
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D042702:Angiopoietin-2 / Q000097:blood*; D014408:Biomarkers, Tumor / Q000097:blood*; D018278:Carcinoma, Neuroendocrine / Q000097:blood / Q000401:mortality; D053379:Chromogranin A / Q000097:blood; D043169:Endostatins / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000097:blood*; D053495:Osteopontin / Q000097:blood; D042787:Receptor, TIE-2 / Q000097:blood*
chemical_list: C586513:ANGPT2 protein, human; D042702:Angiopoietin-2; D014408:Biomarkers, Tumor; C506150:CHGA protein, human; D053379:Chromogranin A; D043169:Endostatins; D009363:Neoplasm Proteins; D053495:Osteopontin; D042787:Receptor, TIE-2