Endocrine Abstracts

Objectives: We previously published the result of CYP24A1 gene expression in one hundred, solely papillary thyroid carcinoma (PTC) compared to its own tumour free control from the same patient. We report an increase in CYP24A1 gene transcription in more than half of analysed PTCs. Elevated CYP24A1 protein expression was also observed in the cancerous tissue section compared to peritumoural normal thyroid tissue. In the present study we aimed to examine CYP24A1 gene transcription in thyroid fine-needle aspiration biopsy (FNAB) specimens and follow up the patients for 2 years.

Methods: The gene expression analyses of 42 thyroid FNABs were carried out by Taqman probe-based quantitative real-time RT-PCR. The somatic mutation states of BRAF, NRAS, HRAS, KRAS oncogenes as well as ELE1/RET and CCDC6/RET rearrangements were also tested. Genomic DNA and total RNA were isolated from each sample using Roche High Pure kits.

Results: Eight males and 34 females participated in the study. The mean age was 51.43 years. Cytology results of 28 FNABs were benign and 14 were malignant. Within the malignant specimens 13 papillary and 1 follicular type carcinoma were recognised. Altogether, 6 BRAF (rs113488022) mutations, 1 ELE1/RET translocation were detected in the malignant FNAB samples and one benign biopsy carried HRAS (rs28933406) mutation. CYP24A1 gene expressions were noticed only in five FNAB samples diagnosed with PTC. We could not determine CYP24A1 specific mRNA in the benign samples. During the follow up period we identified malignant transformation in three cases from the 28 initially cytological benign FNABs. In all of these three cases PTC were certified.

Conclusion: It is well established, that CYP24A1 gene activity is elevated in various cancers including thyroid carcinoma might be to protect tumour tissue from the anti-proliferative and pro-apoptotic effects of 1.25-vitamin D3. Our results show that changes of CYP24A1 gene expression have no predictive value in precancerous states of thyroid and it could not help to complete the diagnosis of FNAB cytology.