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The genetics underlying thyroid cancer dedifferentiation is only partly understood and has not yet been characterised using comprehensive pan-genomic analyses. We investigated a unique case with synchronous follicular thyroid carcinoma (FTC), poorly differentiated thyroid carcinoma (PDTC), and anaplastic thyroid carcinoma (ATC), as well as regional lymph node metastases from the PDTC and ATC from a single patient using whole-genome sequencing (WGS). The FTC displayed mutations in CALR, RB1, and MSH2, and the PDTC exhibited mutations in TP53, DROSHA, APC, TERT, and additional DNA repair genes - associated with an immense increase in sub-clonal somatic mutations. All components displayed an overrepresentation of C>T transitions with associated microsatellite instability (MSI) in the PDTC and ATC, with borderline MSI in the FTC. Clonality analyses pinpointed a shared ancestral clone enriched for mutations in TP53-associated regulation of DNA repair and identified important sub-clones for each tumour component already present in the corresponding preceding lesion. This genomic characterisation of the natural progression of thyroid cancer reveals several novel genes of interest for future studies. Moreover, the findings support the theory of a stepwise dedifferentiation process and suggest that defects in DNA repair could play an important role in the clonal evolution of thyroid cancer. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Telomere maintenance, a hallmark of cancer for cell immortalization, is commonly achieved by telomerase activation through induction of the telomerase reverse transcriptase (TERT) gene. Pheochromocytomas (PCC) and abdominal paragangliomas (PGL) (together PPGL) are endocrine tumours for which TERT promoter mutations and telomerase activation have been previously reported [1]. Only 10-15% of PPGL metastasize, however in the absence of metastases, the identification of malignant disease is a diagnostic dilemma. Over 30% of PPGL exhibit a constitutional mutation in one of 14 susceptibility genes, and additionally, recurrent somatic mutations occur frequently [2]. Mutations in VHL, SDHx and EPAS1 define the Cluster 1 mRNA expression profile with pseudo-hypoxic effects, and mutations in HRAS, MAX, NF1, RET and TMEM127 define Cluster 2 with activation of kinase-signaling pathways [2]. This article is protected by copyright. All rights reserved.

BACKGROUND The telomerase reverse transcriptase (TERT) promoter mutations C228T and C250T have been found in many malignancies, including in thyroid carcinomas. However, it is unclear how early these mutations occur in thyroid tumorigenesis. METHODS The study included primary tumors from 58 patients initially diagnosed with follicular thyroid adenoma (FTA), a benign entity, 18 with atypical FTA (AFTA) having an uncertain malignant potential, and 52 with follicular thyroid carcinoma (FTC). Sanger sequencing was used to investigate the mutational status of the TERT promoter. Telomere length and TERT messenger RNA (mRNA) expression were determined using quantitative polymerase chain reaction (PCR). Telomerase activity was assessed using a Telomerase PCR enzyme-linked immunosorbent assay kit. RESULTS The C228T mutation was identified in 1 of 58 FTA (2%) and 3 of 18 AFTA (17%) samples. These 4 tumors all expressed TERT mRNA and telomerase activity, whereas the majority of C228T-negative adenomas lacked TERT expression (C228T versus wild-type, P = .008). The C228T mutation was associated with NRAS gene mutations (P = .016). The patient with C228T-mutated FTA later developed a scar recurrence and died of FTC, whereas none of the remaining 57 patients with FTA had recurrence. No recurrence occurred in 3 patients with AFTA who carried C228T during the follow-up period (36-285 months). Nine of the 52 FTCs (17%) exhibited the TERT mutation (8 of 9 C228T and 1 of 9 C250T), and the presence of the mutation was associated with shorter patient survival. CONCLUSIONS TERT promoter mutations may occur as an early genetic event in thyroid follicular tumors that have not developed malignant features on routine histopathological workup. Cancer 2014;120:2965–2979. © 2014 American Cancer Society.

The putative tumor suppressor NORE1A (RASSF5) is a member of the Ras association domain family and is commonly inactivated in human cancer. The closely related gene family member and functional collaborator RASSF1A is a bona fide tumor suppressor and is frequently involved in neuroblastoma. In the present study, we sought to investigate the role of NORE1A in human neuroblastoma. A panel of tumors (36 neuroblastomas and 4 ganglioneuromas) and neuroblastoma cell lines was assessed for NORE1A gene expression by Taqman quantitative RT-PCR. Promoter methylation was quantitatively determined by methylation sensitive pyrosequencing. The antitumourigenic role was functionally investigated in Nore1a transfected SK-N-BE (2) cells by fluorescent inhibition of caspase activity and BrdU incorporation assays. Neuroblastoma cells showed very low or absent NORE1A mRNA expression, which could not be reversed by trichostatin A or 5-aza-cytidine treatments. Neuroblastoma tumors showed suppressed NORE1A gene expression that was particularly pronounced in cases without MYCN amplification or 1p loss. Methylation of the NORE1A promoter was not observed in primary tumors and only one out of seven neuroblastoma cell lines displayed weak partial methylation. Transient expression of Nore1a resulted in enhanced apoptosis and delayed cell cycle progression. In conclusion NORE1A appears to be strongly suppressed in neuroblastic tumors and reconstitution of its expression diminishes the tumorigenic phenotype. Promotor methylation is not a common mechanism responsible for NORE1A transcriptional suppression in this tumor type.

Summary objective Parathyroid adenomas frequently harbour deletions of genomic DNA at chromosome regions 1p, 6q and 11q. In this study we related clinical characteristics in 56 patients with primary hyperparathyroidism (pHPT) to loss of heterozygosity (LOH) in these chromosome regions. design LOH analysis was performed on 56 sporadic parathyroid tumours using a total of 18 microsatellite markers for chromosome regions 1p, 6q and 11q. LOH was identified, for either radioactive or fluorescent labelled markers, as total absence or reduction of ≥ 50% of the signal intensity of an allele in the tumour DNA vs. constitutional DNA. patients Twenty-one of the patients were recruited by a population-based screening for pHPT and the remaining pHPT patients were gathered from routine clinical practice. results In total, 27%, 23% and 23% of the tumours showed LOH at 1p, 6q and 11q, respectively. LOH at both 1p and 11q was more common in the screening-detected pHPT patients compared to those recruited from clinical practice (38%vs. 20%; P= 0·02 and 43%vs. 11%; P= 0·001, respectively), while allelic loss at 6q was more prevalent in the latter group (11%vs. 31%; P= 0·001). No apparent relationships between LOH at 1p, 6q, and 11q and clinical characteristics, such as glandular weight, serum levels of PTH or calcium, were demonstrated. Moreover, additional LOH analysis of chromosome 1p suggested a putative parathyroid tumour suppressor gene(s) in the region between markers DS214 and D1S503, spanning approximately 6 cM. conclusion A high frequency of LOH at 1p and 11q in tumours of screening-detected pHPT patients is intriguing, and may suggest that inactivation of known (the MEN1 gene) and putative tumour suppressor genes at these chromosomal regions is associated with a more benign disease.