Expression accrue de l'endothéline-1 et de son récepteur mitogène ET(A) dans le cancer papillaire de la thyroïde chez l'homme.

Since its discovery in 1988, endothelin has initiated intense research activities, showing that it was not only a vasoconstrictor and mitogenic peptide produced by the vascular endothelium but also a ubiquitous molecule with various functions. A production of ET-1 has been evidenced in the thyroid and ET-1 receptors have been detected on thyroid cells. Produced by the vessels and the thyrocytes, ET-1 could exert paracrine and/or autocrine effects on vascular tone in the thyroid and on some functions of thyrocytes. Because of proliferative effects, its role in thyroid diseases could involve goitrogenesis and carcinogenesis. Using thyroid samples obtained at the time of surgery, we demonstrated increased expressions of ET-1 and its mitogenic receptor ET(A) in papillary carcinoma of the thyroid. Immunohistochemical studies and real-time quantitative polymerase chain reaction (RTQ-PCR) were used for this purpose. As demonstrated in other cancers, activation of endothelin axis, particularly through ET(A) receptor could contribute to cell proliferation, cell survival, angiogenesis and the development of bone metastases. ET-1 is also a proinflammatory mediator and we demonstrated an overexpression of ET-1 and of its receptor ET(A) in Hashimoto's thyroiditis. This suggests a role of ET-1 as a cytokine. In nodular goitre, ET-1 is also overexpressed but to a lesser extent than in papillary thyroid carcinoma and in Hashimoto's thyroiditis. Finally, antagonists of ET-1 receptors are currently under development and could be used in man. They could open new therapeutic perspectives in the treatment of metastatic thyroid carcinoma.