Prospects of using the microRNA expression level and parameters of nucleolar organizer regions in the choice of surgical tactics for follicular thyroid tumor of uncertain malignant potential
Authors: Kazachkov E. L. , Il'ina T. E. , Sergijko S. V. 
Published: January 2024

BACKGROUND: According to modern concepts [1], microRNAs modulate the expression of eukaryotic genes with different oncogenetic directions of action. according to the data from the scientifi literature [2–4], microRNA-146b, -199b can be used for typing thyroid neoplasms, -221, -223, -31, -375, -451a, -551b, etc. Nucleolar organizers (NOR) are sections of chromosomes that form a nucleolus inside the cell nucleus [5–7]. The condition of the regions of nucleolar ribosome organizers (AgNORs) is a marker of the rate of cell proliferation, since they are involved in the regulation of the mitotic cycle [8], and in thyroid pathology [9].

AIM: To evaluate the diagnostic significance of the level of expression of some microRNAs and the number of regions of nucleolar organizers in thyroid tissue in the case of follicular thyroid tumor of uncertain malignant potential (FT-UMP) to objectify approaches to the validity of the chosen surgical tactics.

MATERIALS AND METHODS: In our study of 3960 patients with surgery due to various thyroidopathies in 2018–2021 on the basis of the thyroid center of Chelyabinsk. 2063 patients were operated on for tumor pathology. In this group, in 98 cases (the study group), FT-UMP was diagnosed based on morphological criteria of neoplasm [10]. This accounted for 4.75% of all surgical tumor pathology during this time. The study group studied the profile, the level of microRNA expression by real-time PCR and the regions of nucleolar organizers in 98 cases of FT-UMP, which amounted to 4.75% of all those operated for thyroid tumors over four years.

RESULTS: In 29 (29.6%) cases, a microRNA spectrum characteristic of malignant neoplasms was registered in the tumor tissue. In the remaining 69 (70.4%) cases out of 98 observations, the spectrum and level of microRNA expression corresponded to follicular adenoma. Statistically significant differences in the average number of AgNORs and the ratio between the cell area and the number of AgNORs granules were revealed within the formed subgroups. The study found that an increase in the average number of AgNORs and the ratio of the core area to the number of silver nitrate granules in the 2nd subgroup relative to the 1st, as well as the presence of type II cells indicates the appearance of proliferating tumor cells in the neoplasm and can be considered as prognostic criteria for tumor malignancy. These results are consistent with the obtained indicators of molecular genetic research

CONCLUSION: The data can serve as additional criteria for assessing the proliferative activity of the follicular epithelium in thyroid neoplasia. Including clarifying the potential of malignancy. The conditionally malignant variant diagnosed before the operation will justify the need and scope of surgical intervention, and when identifying a set of criteria for conditionally benign HPV, it can be recommended to adhere to wait-and-see tactics.