Significance of Furin Expression in Thyroid Neoplastic Transformation

SIMPLE SUMMARY: Angiotensin-Converting Enzyme 2 (ACE2), Transmembrane Serine Protease 2 (TMPRSS2), and Furin are highly expressed in the normal thyroid gland. The putative role played by these molecules in thyroid tumours has not been thoroughly explored to date. Our study shows that the downregulation of ACE2 mRNA and overexpression of Furin mRNA may play a role in thyroid neoplastic transformation. ACE2 mRNA expression was lower in thyroid neoplasms, as for Furin an increased expression in neoplastic lesions was observed. Furin revealed a high discriminative power between normal adjacent and neoplastic thyroid tissue. Its high expression was significantly correlated with poor prognostic features for thyroid neoplasia. ABSTRACT: Angiotensin-Converting Enzyme 2 (ACE2), Transmembrane Serine Protease 2 (TMPRSS2), and Furin were known to be key players in the SARS-CoV-2 infection, and the thyroid gland was revealed to be one of the relevant targets of the virus. Regardless of the viral infection, the expression of these molecules in the thyroid gland and their putative role in the neoplastic transformation of the thyrocytes has not been thoroughly explored. In this work, we aimed to characterize the mRNA and protein expression pattern of ACE2, TMPRSS2, and Furin in a series of patients with thyroid lesions. Our main results revealed a significantly decreased expression of ACE2 mRNA in the thyroid neoplasms in comparison to normal adjacent tissue. Furin mRNA was significantly increased in thyroid neoplasms when compared to normal adjacent tissue. In addition, a higher Furin mRNA level in thyroid carcinomas was associated with the presence of lymph node metastasis. Furin mRNA expression revealed a high discriminatory power between adjacent tissue and neoplasms. Protein expression of these molecules did not correlate with mRNA expression. Our study shows the mRNA downregulation of ACE2 and overexpression of Furin in thyroid neoplasms. Further studies are required to clarify if Furin expression can be a potential diagnostic indicator in thyroid neoplasia.