Endocrine Abstracts

Introduction: Multinodular Goiter (MNG) is a thyroid neoplastic disease thirteen times more common in women than in men. While a local effect of estrogens at cellular levels could affect there can be other causes to explain the gender difference in incidence such as diet, environmental factors, genetic causes or alterations in metabolic pathways.

Cellular effects of estrogens in human thyrocytes although previously studied are not completely clarified. Some reports suggest that they increase cell proliferation while others do not.

TGFb is a cytokine that has an important role in the normal function of the thyrocyte. It has two independent actions: an antiproliferative and a pro-apoptotic action. Previous results in our group, show that in the absence of other growth factors TGFb reveals its pro-apoptotic action and such action is related to a decrease in the levels of p27Kip1.

Aims: To study the effect of estrogens in the apoptotic action of TGFb in human normal thyrocytes in comparison with MNG thyrocytes.

Materials and methods: We used primary cultures of normal human thyrocytes (NT) and MNG from our bank of human thyrocytes in culture (BANTTIC). Our follicular cells in culture maintain the thyroid phenotype (TaqMan) and express alpha and beta estrogen receptors (immunohistochemistry). They were treated with TGFb or vehicle in the presence of a range of physiological concentrations of b-estradiol or vehicle following a time-course.

Apoptosis was measured by Hoescht. p27Kip1 levels were quantified by Western blot.

Results: In NT and MNG, the presence of physiological doses of estradiol (0.01 to 1 nM) blocked the pro-apoptotic effect of TGFb. In parallel, estradiol blocked the effect of TGFb on the repression of p27Kip1 levels.

Conclusions: Our results suggest an antiapoptotic action of estrogen against TGFb. This action may be mediated through p27Kip1.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details unavailable.