Aims: 

Type I receptor for transferrin (TfR1/CD71) is overexpressed in several malignant tumors.

We investigated the expression of TfR1/CD71 in benign and malignant thyroid tissues.

Methods and results: 

Tissue samples, including benign lesions and follicular-derived carcinomas, from 241 patients and a total of 35 benign and malignant fresh specimens were assayed for TfR1/CD71 expression by RT-PRC, Western blot and immunohistochemistry. We found that transcription of TfR1/CD71 gene is constitutive in thyroid epithelia, but the mRNA is differently translated in benign and malignant tissues. In benign tissues low levels of TfR1/CD71 were found, whereas most carcinomas exhibited overexpression of the receptor, predominantly in the cytoplasm of neoplastic cells. The highest expression level was detected in primary and metastatic papillary carcinomas and anaplastic carcinomas, with a positivity ranged from 86% to 100% of the cases.

Conclusions: 

Our findings suggest that altered expression of TfR1/CD71 is a marker of malignancy in thyroid tissues where it is useful in distinguishing PTC from benign lesions with PTC-like cytoarchitectural alterations and follicular variant PTC from benign follicular-patterned lesions. The present observations support the rationale for the use of radiolabeled transferrin/transferrin analogs and/or anti-TfR1/CD71 antibodies for diagnostic and/or radiotherapeutic purposes in TfR1/CD71-expressing thyroid tumors.