Abstract 3553: Three-dimensional (3D) telomere signatures of sporadic pediatric papillary thyroid carcinoma (PTC)

Abstract

Abstract The incidence of thyroid carcinoma has increased worldwide, including in pediatric patients. Papillary thyroid carcinoma (PTC) is the most common subtype. Previous studies have suggested that clinical presentation and outcome diverge between pediatric and adult PTC and that this difference is likely due to distinct genetic alterations. BRAF V600E point mutation is highly prevalent in adults, while genetic fusions (RET/PTC, AGK-BRAF, ETV6-NTRK3) are the most prevalent events in the pediatric population. As telomere loss or dysfunction results in aneuploidy and chromosomal rearrangements, which can promote carcinogenesis, we investigated the three-dimensional (3D) structure of the telomeres in the nuclei from 21 pediatric patients (≤18 y.o), representing 16 PTC cases (with paired normal and tumor tissues for five of them) and five normal thyroid tissues from patients undergoing thyroidectomy for reasons other than cancer. We performed quantitative fluorescence in situ hybridization (FISH), 3D imaging, and 3D telomere analysis using TeloView® software to examine telomere dysfunction. The parameters examined included total number of signals (numbers of telomeres), total number of telomere aggregates, a/c ratio (indicating the phase of the cell cycle), total intensity (telomere length) and nuclear volume. Thyroid cancer cells showed lower average intensity of signals (p<0.0001) and lower intensity signals (p<0.0001), as well as higher nuclear volume (p<0.0001), compared to normal thyroid cells. In addition, tumour cells showed a higher a/c ratio (p<0.0001), indicating that they are more actively dividing than normal cells, which correlates with the high proliferation rate of cancer cells. We did not observe any alterations related to the total number of telomere signals and total number of aggregates, which suggests no significant aneuploidies occurring with these samples. The 3D nuclear telomere signature was able to detect differences in telomere architecture in tumours, compared to normal. Further analysis is necessary to define whether nuclear telomere architecture and specific genetic alterations observed in pediatric thyroid cancer are associated. Citation Format: Luiza Sisdelli, Maria Isabel Cordioli, Fernanda Vaisman, Osmar Monte, Carlos Longui, Adriano N. Cury, Monique O. Freitas, Aline Rangel-Pozzo, Sabine Mai, Janete Cerutti. Three-dimensional (3D) telomere signatures of sporadic pediatric papillary thyroid carcinoma (PTC) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3553.