Assessment of RET/PTC1 and RET/PTC3 rearrangements in fine-needle aspiration biopsy specimens collected from patients with Hashimoto's thyroiditis

Thyroid aspirates, eligible for the study, were obtained from 26 patients with Hashimoto's thyroiditis by fine-needle aspiration biopsy (FNAB). Each aspirate was smeared for conventional cytology, while its remaining part was immediately washed out of the needle. The cells, obtained from the needle, were used in further investigation. Total RNA from FNAB was extracted by use of an RNeasy Micro Kit, based on modified Chomczynski and Sacchi's method and reverse transcription (RT-PCR) was done. Quantitative evaluation of RET/PTC1 and RET/PTC3 rearrangements by real-time PCR was performed by an ABI PRISM？ 7500 Sequence Detection System. In the study, PTC tissues with known RET/PTC1 and RET/PTC3 rearrangements served as a reference standard (calibrator), while β-actin gene was used as endogenous control.Amplification reactions were done in triplicate for each examined sample. No RET/PTC1 and RET/PTC3 rearrangements were found in the examined samples.Our results indicate that RET/PTC1 and RET/PTC3 rearrangements in Hashimoto's thyroiditis, if any, are rather rare events and further investigations should be conducted in order to determine molecular changes, connecting Hashimoto's thyroiditis with PTC.Chromosomal rearrangements involving RET receptor tyrosine kinase (TK) protooncogene (RET/PTC) are a specific feature of papillary thyroid carcinoma (PTC). The RET protooncogene is activated by fusion of 3'-terminal portion of RET, coding for TK domain, with the 5' terminal region of different unrelated genes, leading to constitutive activation of the RET TK [1]. There are - at least -15 different RET/PTC rearrangements [2], but the two: RET/PTC1 and RET/PTC3 are the most common ones [3]. RET/PTC1 is formed by fusion with the H4 gene [1], and RET/PTC3 by fusion with the ELE1 (also designed NCOA4, RFG or ARA70) gene [4]. However, apart from RET/PTC1 and RET/PTC3, all the other variants of rearrangements do not seem to have an important role in the pathogenesis of PTC since they