碘转运体与甲状腺疾病

Relation Between Iodide Transporters and Thyroid Diseases

目的探讨3种碘转运体的表达与甲状腺疾病的关系。方法采用文献回顾的方法对钠碘同向转运体(Na+/I-symporter,NIS)、pendrin和人类顶膜碘转运体(human apical iodide transporter,hAIT)在各种甲状腺疾病的表达及临床相关性加以综述。结果在正常甲状腺组织中,NIS表达于滤泡细胞基底质膜及侧质膜,pendrin及hAIT表达于滤泡细胞顶膜上。对于NIS的研究表明,在甲状腺癌组织中,NIS表达降低或是定位于胞浆;NIS基因突变是导致先天性甲状腺功能减退症的原因之一。pendrin的表达水平与滤泡功能相关:在Graves病和高功能腺瘤中,pendrin高表达,在甲状腺癌中其表达显著降低;在体外实验中其表达与甲状腺癌细胞系分化程度的相关性各文献报道不一。hAIT蛋白表达在高功能甲状腺组织中与正常组织差异不大,而在低功能甲状腺腺瘤中,其表达仅轻度降低或正常;在甲状腺癌中,其表达显著降低。结论3种碘转运体表达异常与甲状腺疾病密切相关,但是其致病机理尚不完全清楚,引起3种碘转运体表达异常的原因也有待进一步研究。

Objective To investigate the clinical significance of the three iodide transporters in thyroid diseases. Methods Literatures about the Na^＋/I^- symporter （NIS）, pendrin and human apical iodide transporter （bAIT） in recent years were reviewed and their expressions in different thyroid diseases were also analyzed. Results NIS proteins express at the basolateral membrane of thyrocytes in normal thyroid tissue, while pendrin and bAIT proteins are limited to the apical membrane of thyrocytes lining in the follicular lumen. In the tissues of thyroid carcinomas, it was found that the NIS proteins expressed in the cytoplasm and their expressions decreased; The mutation of NIS gene may be one of the main causes of congenital hypothyroidism. The expression of prendrin protein may be related to the function of follicles ： its expression level increased significantly both in Graves diseases and toxic adenomas, but significantly decreased in differentiated thyroid carcinoma. However, the correlation between the decrease and the degrees of differentiation of carcinoma cell line are still disputable. The expression of hAIT protein does not significantly altered in hyperfunctioning tissues. It only slightly decreased occasionally in hypofunctioning adenomas, but it decreased significantly in thyroid carcinomas. Conclusion The abnormal expressions of the three iodide transporters may be related closely with the type of thyroid diseases. However, their pathogenic mechanisms and the causes of their abnormal expression are still unknown, which need to be studied further.