Tri-iodothyronine induces proliferation in cultured bovine thyroid cells: evidence for the involvement of epidermal growth factor-associated tyrosine kinase activity

DI FULVIO MAURICIO, COLEONI ALDO H, PELLIZAS CLAUDIA G, MASINI-REPISO ANA M

JOURNAL OF ENDOCRINOLOGY

The Dorset Press, Dorchester

Lugar: Dorset, Great Britain; Año: 2000 vol. 166 p. 173 - 173

0022-0795

dir> The effects of the tri-iodothyronine (T3) secreted by thyroid cells on the growth of the thyrocyte are poorly known. In this study we analyzed the effects of T3 on the proliferation of bovine thyroid follicles in primary culture previously depleted of endogenous T3. Cellular deoxiribonucleic acid (DNA) synthesis, determined by [3H]thymidine incorporation, was stimulated by T3 (0.1-5.0 nM) for 24 h in a concentration-dependent fashion with a maximal effect at 1.0 nM T3 (P<0.01). This T3 action was time-dependent when assayed from 12 to 72 h. The induction of mitogenic activity was corroborated by the increase in proliferating cell nuclear antigen (PCNA) measured by Western blot analysis. PCNA increased after treatment with T3 (0.1-5.0 nM) in a concentration-dependent manner. Since T3 modifies the activity of growth factors whose actions