, Volume 65, Issue 3, pp 623–629 | Cite as

Differential expression of RET isoforms in normal thyroid tissues, papillary and medullary thyroid carcinomas

  • Teresa Ramone
  • Cristina Romei
  • Raffaele Ciampi
  • Alessia Tacito
  • Paolo Piaggi
  • Liborio Torregrossa
  • Clara Ugolini
  • Rossella EliseiEmail author
Original Article



We investigated the expression of RET9 and RET51 isoforms in medullary (MTC), papillary (PTC) thyroid carcinoma, normal thyroid tissues, and pheochromocytoma (PHEO) to verify if these isoforms are present also in follicular thyroid cell-derived tissues, and if there is a differential expression of RET9 and RET51 in MTC.


Nineteen patients with MTC, 18 patients with PTC, 18 samples of contralateral normal thyroid tissues, and 5 cases of PHEO were included in this study. RET isoform expression was studied by real-time RT-PCR.


All MTCs and PHEOs were positive for RET9 and RET51. Fourteen/eighteen (77.7%) PTC cases were positive for RET9 and/or RET51, and four were positive for only one of the genes. In normal thyroid tissues, 3/18 (16.7%) cases were negative for both isoforms, 4/18 (22.2%) were positive for both, and 11/18 (61.1%) were positive for only one. RET isoforms were expressed at different levels in MTC, PHEO, PTC, and normal thyroid tissues: RET9 expression was higher in PHEO than in MTC, PTC, and normal thyroid tissues. RET9 expression was also higher in MTC than in PTC and normal thyroid tissues. No difference was observed between PTC and normal thyroid tissues. A similar pattern of expression was observed for RET51. In addition, RET51 was significantly more expressed than RET9 in MTC, while RET9 was the predominant isoform in PHEO.


Our study documented the expression of the RET9 and RET51 isoforms in normal thyroid and PTC tissues. RET9 and RET51 isoforms were also present in MTC and PHEO. RET51 expression was higher than RET9 expression in MTC, while there was no difference in the expression of these two isoforms in PTC and normal thyroid tissues. RET9 was more highly expressed than RET51 in PHEOs.


RET Medullary thyroid carcinoma Papillary thyroid carcinoma Normal thyroid Isoforms 



This study has been supported by Associazione Italiana Ricerca sul Cancro (IG 2018, cod 21790) and Agenzia Italiana del Farmaco (Cod AIFA-2016-02365049).

Compliance with ethical standards

Conflict of interest

The authors declare that there is no conflict of interest that could affect the impartiality of the reported research.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.


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© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Clinical and Experimental MedicineUnit of Endocrinology University of PisaPisaItaly
  2. 2.Department of Surgical and Medical Pathology, Unit of PathologyUniversity of PisaPisaItaly

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