title: Enzymatic activity of type 1 iodothyronine deiodinase in selected liver tumors.
abstract: BACKGROUND
  Type 1 iodothyronine deiodinase (D1) converts thyroxin (T4) into tri-iodothyronine (T3). Strong evidence indicates that thyroid hormone metabolism is disturbed in neoplasms such as thyroid and breast cancer. However, there is limited data concerning the function of the D1 enzyme in liver tumors. We aimed to estimate the enzymatic activity of D1 in two different common liver tumors.
  
  
  METHODS
  We obtained 20 tumor samples from patients who had undergone a liver resection. Of the tissue samples, there were 13 benign lesions of focal nodular hyperplasia (FNH) and 7 malignant lesions of hepatocellular carcinomas (HCC). The D1 activity was assessed by measuring the amount of radioactive iodine released in reaction to D1-catalysed deiodination. Groups were compared by the Mann-Whitney non-parametrical test for independent trials, and the Kruskal Wallis test.
  
  
  RESULTS
  The enzymatic activity of D1 was not significantly altered in the FNH group (median = 536 fmol/mg of protein/min; p = 0.972) and HCC group (367 fmol/mg; p = 0.128) when compared to matched normal liver parenchyma controls (546 fmol/mg and 556 fmol/mg, respectively).
  
  
  CONCLUSIONS
  Liver parenchyma expresses high levels of D1. The results clearly revealed that D1 activity was not significantly different between benign and malignant tumors (FNH and HCC) compared to healthy liver parenchyma cells.
authors.affiliation: Department of General, Transplant and Liver Surgery, Medical University of Warsaw, Poland.
authors.forename: Oskar
authors.initials: O
authors.lastname: Kornasiewicz
authors.affiliation: Department of Internal Medicine and Endocrinology, Medical University of Warsaw, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Dębski
authors.affiliation: Department of General, Transplant and Liver Surgery, Medical University of Warsaw, Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Grat
authors.affiliation: Department of General, Transplant and Liver Surgery, Medical University of Warsaw, Poland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Lenartowicz
authors.affiliation: Department of Internal Medicine and Endocrinology, Medical University of Warsaw, Poland.
authors.forename: Marta
authors.initials: M
authors.lastname: Stępnowska
authors.affiliation: Department of Internal Medicine and Endocrinology, Medical University of Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Szałas
authors.affiliation: Department of Internal Medicine and Endocrinology, Medical University of Warsaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Bar-Andziak
authors.affiliation: Department of General, Transplant and Liver Surgery, Medical University of Warsaw, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Krawczyk
keywords: focal nodular hyperplasia; hepatocellular carcinomas; thyroxin