epidermal-growth-factor and Adenoma--Oxyphilic

The activity of thymidine kinase (TK-EC 2.7.1.21)--an enzyme functioning as a part of the pyrimidine salvage pathway of DNA synthesis--is closely related to growth processes. The aim of the study was to measure TK activity in homogenates of human thyroid tissue of the following types: non-toxic nodular goiter (NTNG)--macroscopically unchanged tissue, non-toxic adenoma (NTA), and toxic adenoma (TA) (obtained from patients, who--before the surgery--had been treated with thyrostatic drugs for thyrotoxicosis). Thyroid tissue was obtained from female patients subjected to subtotal thyroidectomy at the Department of Endocrine Surgery, Medical University of Lódź. Thyroid homogenates were incubated in the presence of epidermal growth factor (EGF), used in five different concentrations (0.1 ng/ml, 1 ng/ml, 10 ng/ml, 100 ng/ml, 1000 ng/ml). TK activity was estimated by chromatographic measurements of the amount of the main reaction product--deoxythymidine monophosphate.. 1) We did not observe any significant difference between TK activity in the homogenates of the thyroid tissue collected from NTNG and NTA; TK activity was clearly higher in the homogenates of adenomatous tissue, collected from the patients with TA; 2) EGF increased TK activity in the homogenates of the macroscopically unchanged tissue, collected--during surgery--from the patients with NTNG, as well as in homogenates of thyroid tissue from NTA; 3) In case of hyperactive thyroid tissue, obtained from TA, EGF tended to increase TK activity, however, without any statistical differences. Our results confirm TK increased activity in hyperactive thyroid tissue. At the same time, the obtained data suggest a certain role of EGF in goiter formation in humans.

Topics: Adenoma, Oxyphilic; Animals; Enzyme Activation; Epidermal Growth Factor; Female; Goiter, Nodular; Humans; Thymidine Kinase; Thyroid Neoplasms

Heat shock protein 90 (HSP90) serves as a chaperone protein and plays a critical role in tumor cell growth and/or survival. Geldanamycin, a specific inhibitor of HSP90, is cytotoxic to several human cancer cell lines, but its effect in thyroid cancer is unknown. We, therefore, investigated the effect of geldanamycin on cell proliferation, oncoprotein expression, and invasion in human thyroid cancer cell lines. We used six thyroid cancer cell lines: TPC-1 (papillary), FTC-133, FTC-236, FTC-238 (follicular), XTC-1 (Hürthle cell), and ARO (anaplastic). We used the dimethyl-thiazol-diphenyltetrazolium bromide assay, a clonogenic assay, an apoptotic assay, and a Matrigel invasion assay. We evaluated oncoprotein expression using Western blots and flow cytometry. After 6 d of treatment with 50 nM geldanamycin, the percent inhibition of growth was 29.4% in TPC-1, 97.5% in FTC-133, 96.7% in FTC-236, 10.8% in FTC-238, 70.9% in XTC-1, and 45.5% in ARO cell lines. In the FTC-133 cell line, geldanamycin treatment decreased clonogenicity by 21% at a concentration of 50 nM; geldanamycin induced apoptosis and down-regulated c-Raf-1, mutant p53, and epidermal growth factor (EGF) receptor expression; geldanamycin inhibited EGF-stimulated invasion. In conclusion, geldanamycin inhibited cancer cell proliferation, down-regulated oncoproteins, and inhibited EGF-induced invasion in thyroid cancer cell lines.

Topics: Adenocarcinoma, Follicular; Adenoma, Oxyphilic; Antibiotics, Antineoplastic; Apoptosis; Benzoquinones; Carcinoma, Papillary; Cell Division; Down-Regulation; Epidermal Growth Factor; ErbB Receptors; HSP90 Heat-Shock Proteins; Humans; In Vitro Techniques; Lactams, Macrocyclic; Mutation; Proto-Oncogene Proteins c-raf; Quinones; Thyroid Neoplasms; Tumor Cells, Cultured; Tumor Suppressor Protein p53