The purpose of this study was to compare thyroid hormone metabolism between non-cancerous tumor-surrounding human kidney tissues and renal clear cell carcinomas (RCCC). The material consisted of samples taken from 10 RCCC patients of both sexes and three grades of differentiation, G1 to G3. We showed that, similar to rat tissue, type I 5' monodeiodinase (5'DI) expression is heterogeneous within the human kidney. We also found a poor correlation between 5'DI activity and mRNA level in non-cancerous tumor-surrounding tissue suggesting significant post-transcriptional regulation of 5'DI expression by an unidentified process in the human kidney. In all RCCC tissues both 5'DI activity and mRNA levels were undetectable. This suggests either loss of human 5'DI gene expression during neoplastic transformation or the origination of RCCC from a tubular cell type that does not express 5'DI.

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Type 1 5'-deiodinase is one of two isoenzymes that participate in conversion of prohormone thyroxine into triiodothyronine (T3). A decrease in type 1 5'-deiodinase expression was observed in renal clear cell carcinoma, thyroid cancer, and lung cancer. The aim of this study was to evaluate type 1 5'-deiodinase activity and mRNA level in breast cancer tissue and non-cancerous surrounding breast tissue. Material was collected from 36 patients undergoing radical mastectomy or local tumor resection. In all non-cancerous breast tissues, type 1 50-deiodinase activity was found to be at a very low or immeasurable level, and type 1 5'-deiodinase mRNA was detected only in 2 out of the 36 samples. By contrast, 20 out of the 36 breast cancer tissues, mainly grades G1 and G2, expressed abundant type 1 5'-deiodinase activity and/or a high mRNA level. Our data demonstrated the presence of type 1 5'-deiodinase in well-differentiated breast cancer tissue. High enzymatic activity of type 1 50-deiodinase can potentially lead to an increase in the production of T3, which may affect target gene transcription, including genes responsible for energy expenditure, growth, differentiation, and proliferation.

Sialylation of cell components is an important immunomodulating mechanism affecting cell response to hormones and adhesion molecules. To study alterations in sialic acid metabolism in Graves' disease (GD) we measured the following parameters in various human thyroid tissues: lipid-bound sialic acid (LBSA) content, ganglioside profile, total sialyltransferase activity, and the two major sialyltransferase mRNAs for sialyltransferase-1 (ST6Gal I) and for sialyltransferase-4A (ST3Gal I). Fragments of toxic thyroid nodules (TN), nontoxic thyroid nodules (NN) and nontumorous tissue from patients with nodular goiter or thyroid cancer were used as a control (C). The LBSA content and sialyltransferase activity were the highest in the GD group (164 +/- 4.44 versus 120 +/- 2.00 nmoL/g, p = 0.005 and 1625 +/- 283.5 versus 324 +/- 54.2 cpm/mg of protein, p < 0.005 compared to control group C). Ganglioside profile in the GD group was similar to that in control tissues. Sialyltransferase- 1 mRNA and sialyltransferase-4A mRNA levels were significantly higher in the GD group than in the control group (12.52 +/- 6.90 versus 2.54 +/- 1.24 arbitrary units, p < 0.005 and 2,49 +/- 1.16 versus 1.23 +/- 0.46 arbitrary units, p < 0.05, respectively). There was a positive correlation between the increased sialyltransferase-1 mRNA level and the TSH-receptor antibody titer determined by the TRAK test. These results indicate that sialyltransferases expression and activity are increased in GD. Exact mechanism of this upregulation remains unknown, though one of possible explanations is the activation of the thyrotropin (TSH) receptor.

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