The Role of Epigenetic Alterations in Papillary Thyroid Carcinogenesis

Papillary thyroid carcinoma (PTC) accounts for over 80% of all thyroid malignancies. The molecular pathogenesis remains incompletely clarified although activation of the RET fusion oncogenes, and RAS and BRAF oncogenes, has been well characterized. Novel technologies using genome-wide approaches to study tumor genomes and epigenomes have provided great insights into tumor development. Growing evidence shows that acquired epigenetic abnormalities participate with genetic alterations to cause altered patterns of gene expression/function. It has been established beyond doubt that promoter cytosine methylation in CpG islands, and the subsequent gene silencing, is intimately involved in cancer development. These epigenetic events very likely contribute to significant variation in gene expression profiling, phenotypic features, and biologic characteristics seen in PTC. Hypermethylation of promoter regions has also been analyzed in PTC, and most studies have focused on individual genes or a small cohort of genes implicated in tumorigenesis

Minimally Invasive Parathyroidectomy

Minimally invasive parathyroidectomy (MIP) is an operative approach for the treatment of primary hyperparathyroidism (pHPT). Currently, routine use of improved preoperative localization studies, cervical block anesthesia in the conscious patient, and intraoperative parathyroid hormone analyses aid in guiding surgical therapy. MIP requires less surgical dissection causing decreased trauma to tissues, can be performed safely in the ambulatory setting, and is at least as effective as standard cervical exploration. This paper reviews advances in preoperative localization, anesthetic techniques, and intraoperative management of patients undergoing MIP for the treatment of pHPT

Identification of Somatic Mutations in Parathyroid Tumors Using Whole-Exome Sequencing

ContextThe underlying molecular alterations causing sporadic parathyroid adenomas that drive primary hyperparathyroidism have not been thoroughly defined.ObjectiveThe aim of the study was to investigate the occurrence of somatic mutations driving tumor formation and progression in sporadic parathyroid adenoma using whole-exome sequencing.DesignEight matched tumor-constitutional DNA pairs from patients with sporadic parathyroid adenomas underwent whole-exome capture and high-throughput sequencing. Selected genes were analyzed for mutations in an additional 185 parathyroid adenomas.ResultsFour of eight tumors displayed a frame shift deletion or nonsense mutation in MEN1, which was accompanied by loss of heterozygosity of the remaining wild-type allele. No other mutated genes were shared among the eight tumors. One tumor harbored a Y641N mutation of the histone methyltransferase EZH2 gene, previously linked to myeloid and lymphoid malignancy formation. Targeted sequencing in the additional 185 parathyroid adenomas revealed a high rate of MEN1 mutations (35%). Furthermore, this targeted sequencing identified an additional parathyroid adenoma that contained the identical, somatic EZH2 mutation that was found by exome sequencing.ConclusionThis study confirms the frequent role of the loss of heterozygosity of chromosome 11 and MEN1 gene alterations in sporadic parathyroid adenomas and implicates a previously unassociated methyltransferase gene, EZH2, in endocrine tumorigenesis

Потребительский экстремизм как правовое явление

Материалы XIII Междунар. науч. конф. студентов, магистрантов, аспирантов и молодых ученых, Гомель, 21–22 мая 2020 г

New Insights in Genetic and Epigenetic Mechanisms Involved in Parathyroid Tumorigenesis

Primary hyperparathyroidism (pHPT) is a pathology associated with one or multiple hyperfunctioning parathyroid glands.  The disease prevalence occurs in roughly 1-2% of the population primarily post-menopausal women.  The molecular pathology of the disease is poorly understood.  Elevated serum calcium levels in the setting of an inappropriately elevated parathyroid hormone level are indicative of the disease process.  The ultimate treatment of the disease is to remove the hyperfunctioning gland. The aim of this thesis was to examine potential genetic and epigenetic aberrations that are potentially disease causing. The methylation signature of normal and pathological parathyroid tissue has yet to be investigated.  DNA was bisulphite modified and analyzed using the Infinium HumanMethylation27 BeadChip. Distinct hierarchical clustering of genes with altered DNA methylation profiles in normal and pathologic parathyroid tissue was evident.  DNA hypermethylation of CDKN2B, CDKN2A, WT1, SFRP1, SFRP2, and SFRP4 known to be important in the development of parathyroid tumors were associated with reduced gene expression in both benign and malignant parathyroid tumors. Familial primary hyperparathyroidism (FPHPT) may occur due to an underlying germ-line mutation in the MEN1, CASR, or HRPT2/CDC73 genes.  Eighty-six young (≤45 years of age) patients with clinically non-syndromic PHPT underwent genetic analysis.  Eight of 86 (9.3%) young patients with clinically non-familial PHPT displayed deleterious germ-line mutations in the susceptibility genes (4 MEN1, 3 CASR, and 1 HRPT2/ CDC73). Accumulation of non-phosphorylated active β -catenin has been reported to commonly occur in parathyroid adenomas from patients with primary hyperparathyroidism (pHPT).  We assessed possible β-catenin stabilizing mutations in a large series of parathyroid adenomas. A total of one hundred and eighty sporadic parathyroid adenomas were examined for mutations in exon 3 of the CTNNB1gene. The mutation S33C (TCT >TGT) was detected by direct-DNA sequencing of PCR fragments in 1 out of 180 sporadic parathyroid adenomas (0.68 %). Eight matched tumor-constitutional DNA pairs from patients with sporadic parathyroid adenomas underwent whole-exome capture and high-throughput sequencing.  Four of eight tumors displayed a frame shift deletion or nonsense mutations within the MEN1 gene, which was accompanied by loss of heterozygosity of the remaining wild-type allele.  One tumor harbored a Y641N mutation of the histone methyltransferase EZH2 gene, previously linked to myeloid and lymphoid malignancy formation. Targeted sequencing in the additional 185 parathyroid adenomas revealed a high rate of MEN1 mutations (35%)