IMMUNOHISTOCHEMICAL ANALYSIS EXPRESSION TP73IN ONCOCYTIC FOLLICULAR ADENOMA OF THE THYROID

Abstract

Oncocytic follicular adenomas (FAs) of the thyroid are cells neoplasms of follicular origin that
predominantly consist of large polygonal cells with eosinophilic and granular cytoplasm. According to
some scientific studies, TP73 might play a сertain role in tumor genesis (oncogenesis). Moreover, due
to the absence of p53, oncogenes may attract p73 to induce apoptosis in tumor cells. TP53 is a crucial
tumor suppressor in preventing the cancerous transformation of cells. There was also a particular focus
on the amplification of 1p36 chromosome in oncocytic FA, which contains a tumor nidus of TP73
protein, which is a member of the p53 family, involved as a factor of the cancerous tumor development.
The aim: To evaluate the extent of the genomic instability in oncocytic follicular adenoma of the
thyroid.
Materials and Methods: Twenty-four surgically resected formalin-fixed, paraffin-embedded (FFPE)
thyroid tumors, including 12 oncocytic and 12 normal FAs, were available for the current study. As it was
a retrospective research with minimal risk to the participants, informing patients and taking their consent
was not necessary. The study was authorized by the ethics committee of the Biomedical Sciences High
School of Nagasaki University (protocol No. 15062617) and permitted by the ethics committee of the
State Medical University, Semey (Protocol No. 5, December 15, 2015). The study of archival data of
patients with follicular adenoma of the thyroid was conducted between 2014 and 2016 in the department
of pathomorphology and cytochemistry of the "Regional Oncology Center" (Semey city, Kazakhstan)
and in the scientific laboratory of the Nagasaki University (Japan).
For processing of the research results were used the Mann-Whitney-U test, the exact Fisher
measure, Pearson's correlation analysis. The calculation was made with a help of SAS software
(version 8:2, SAS Institute, Cary, NC, USA). All tests were unilateral and р < 0,05 was considered to be
statistically true measure.
Results: Patients with oncocytic follicular adenoma were older than with normal follicular adenoma
(p = 0.03) and there was no statistically significant difference in tumor size. The study showed, that the
frequency of unstable expression of 53BP1 was vastly higher in the oncocytic follicular adenoma than in
the usual one (p = 0.0028). Our work demonstrated that the level of TP73 immunoreactivity was greatly
higher in oncocytic than in normal FA (p= 0,0001). We have found a significant positive correlation (r =
0.5983, p = 0.0020) between the percentage of tumour cells expressing unstable type of 53BP1 and the
percentage of cells being positive for TP73 expression in oncocytic FA.
Conclusion: It is important to note that we have found a significant positive correlation between the
percentage of tumour cells expressing unstable type of 53BP1 and the percentage of cells being
positive for TP73 expression in oncocytic follicular adenoma. All these data indicate that the oncocytic
follicular adenoma demonstrates an elevated level of TP73 protein, which correlates with the
appearance of a DNA double strand break.