| 1. |
- Barazeghi, Elham, et al.
(författare)
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5-Hydroxymethylcytosine discriminates between parathyroid adenoma and carcinoma
- 2016
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Ingår i: Clinical Epigenetics. - : Springer Science and Business Media LLC. - 1868-7083 .- 1868-7075. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Background: Primary hyperparathyroidism is characterized by enlarged parathyroid glands due to an adenoma (80-85 %) or multiglandular disease (similar to 15 %) causing hypersecretion of parathyroid hormone (PTH) and generally hypercalcemia. Parathyroid cancer is rare (<1-5 %). The epigenetic mark 5-hydroxymethylcytosine (5hmC) is reduced in various cancers, and this may involve reduced expression of the ten-eleven translocation 1 (TET1) enzyme. Here, we have performed novel experiments to determine the 5hmC level and TET1 protein expression in 43 parathyroid adenomas (PAs) and 17 parathyroid carcinomas (PCs) from patients who had local invasion or metastases and to address a potential growth regulatory role of TET1. Results: The global 5hmC level was determined by a semi-quantitative DNA immune-dot blot assay in a smaller number of tumors. The global 5hmC level was reduced in nine PCs and 15 PAs compared to four normal tissue samples (p < 0.05), and it was most severely reduced in the PCs. By immunohistochemistry, all 17 PCs stained negatively for 5hmC and TET1 showed negative or variably heterogeneous staining for the majority. All 43 PAs displayed positive 5hmC staining, and a similar aberrant staining pattern of 5hmC and TET1 was seen in about half of the PAs. Western blotting analysis of two PCs and nine PAs showed variable TET1 protein expression levels. A significantly higher tumor weight was associated to PAs displaying a more severe aberrant staining pattern of 5hmC and TET1. Overexpression of TET1 in a colony forming assay inhibited parathyroid tumor cell growth. Conclusions: 5hmC can discriminate between PAs and PCs. Whether 5hmC represents a novel marker for malignancy warrants further analysis in additional parathyroid tumor cohorts. The results support a growth regulatory role of TET1 in parathyroid tissue.
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| 2. |
- Barazeghi, Elham, et al.
(författare)
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A role for TET2 in parathyroid carcinoma
- 2017
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Ingår i: Endocrine-Related Cancer. - 1351-0088 .- 1479-6821. ; 24:7, s. 329-338
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Tidskriftsartikel (refereegranskat)abstract
- Primary hyperparathyroidism (pHPT) is rarely caused by parathyroid carcinoma (PC, <1-5% of pHPT cases). The TET proteins oxidize the epigenetic mark 5-methylcytosine to 5-hydroxymethylcytosine (5hmC) and inactivation by mutation or epigenetic deregulation of TET1 and TET2 play important roles in various cancers. Recently, we found that 5hmC was severely reduced in all of the analyzed PCs and with deranged expression of TET1 for the majority of PCs. Here, we have examined the expression of the TET2 protein in 15 5hmC-negative PCs from patients who had local invasion or metastases. Cell growth and cell migratory roles for TET2 as well as epigenetic deregulated expression were addressed. Immunohistochemistry revealed very low/undetectable expression of TET2 in all PCs and verified for two PCs that were available for western blotting analysis. Knockdown of TET2 in the parathyroid cell line sHPT-1 resulted in increased cell growth and increased cell migration. DNA sequencing of TET2 in PCs revealed two common variants and no obvious inactivating mutations. Quantitative bisulfite pyrosequencing analysis of the TET2 promoter CpG island revealed higher CpG methylation level in the PCs compared to that in normal tissues and treatment of a PC primary cell culture with the DNA methylation inhibitor 5-aza-2'-deoxycytidine caused increased expression of the methylated TET2 gene. Hence, the data suggest that deregulated expression of TET2 by DNA hypermethylation may contribute to the aberrantly low level of 5hmC in PCs and further that TET2 plays a cell growth and cell migratory regulatory role and may constitute a parathyroid tumor suppressor gene.
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| 3. |
- Meyer-Rochow, Goswin Y., et al.
(författare)
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MicroRNA profiling of benign and malignant pheochromocytomas identifies novel diagnostic and therapeutic targets
- 2010
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Ingår i: Endocrine-Related Cancer. - 1351-0088 .- 1479-6821. ; 17:3, s. 835-846
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Tidskriftsartikel (refereegranskat)abstract
- MicroRNAs (miRNAs) are small RNAs (similar to 22 bp) that post-transcriptionally regulate protein expression and are found to be differentially expressed in a number of human cancers. There is increasing evidence to suggest that miRNAs could be useful in cancer diagnosis, prognosis, and therapy. We performed miRNA microarray expression profiling on a cohort of 12 benign and 12 malignant pheochromocytomas and identified a number of differentially expressed miRNAs. These results were validated in a separate cohort of ten benign and ten malignant samples using real-time quantitative RT-PCR; benign samples had a minimum follow-up of at least 2 years. It was found that IGF2 as well as its intronic miR-483-5p was over-expressed, while miR-15a and miR-16 were under-expressed in malignant tumours compared with benign tumours. These miRNAs were found to be diagnostic and prognostic markers for malignant pheochromocytoma. The functional role of miR-15a and miR-16 was investigated in vitro in the rat PC12 pheochromocytoma cell line, and these miRNAs were found to regulate cell proliferation via their effect on cyclin D1 and apoptosis. These data indicate that miRNAs play a pivotal role in the biology of malignant pheochromocytoma, and represent an important class of diagnostic and prognostic biomarkers and therapeutic targets warranting further investigation.
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| 4. |
- Tacon, Lyndal J., et al.
(författare)
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The glucocorticoid receptor is overexpressed in malignant adrenocortical tumors
- 2009
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 94:11, s. 4591-4599
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Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Adrenocortical carcinoma (ACC) is a rare tumor with a poor prognosis. The Weiss score is the most widely accepted method for distinguishing an ACC from an adrenocortical adenoma (ACA); however, in borderline cases, accurate diagnosis remains problematic. We recently discovered that the glucocorticoid receptor (GR) gene NR3C1 is significantly up-regulated in ACCs compared with ACAs in global gene expression studies. OBJECTIVE: Our objective was to study GR expression in adrenocortical tumors (ACTs) and to assess its utility as an adjunct to the Weiss score. DESIGN: Microarray analysis, real-time quantitative RT-PCR (qPCR), immunohistochemistry, Western blot, and direct sequencing were performed. RESULTS: Analysis of 28 ACTs by microarray and 49 ACTs by qPCR found NR3C1 expression to be up-regulated in ACCs compared with ACAs (P < 0.001). Western blotting and RT-PCR confirmed the presence of the GRalpha isoform in ACCs, and no mutations were detected on direct sequencing. Immunohistochemistry for GR in an overlapping cohort of ACTs demonstrated strongly positive nuclear staining in 31 of 33 ACCs (94%), with negative staining in 40 of 41 ACAs (98%) (P < 0.001). This finding was validated in an external cohort of ACTs, such that 14 of 18 ACCs (78%) demonstrated positive nuclear staining whereas 32 of 33 ACAs (94%) were negative (P < 0.001). CONCLUSIONS: The immunohistochemical finding of nuclear GR staining identified ACCs with high diagnostic accuracy. We propose that GR immunohistochemistry may complement the Weiss score in the diagnosis of ACC in cases that display borderline histology. The possibility that GR is transcriptionally active in these tumors, and may therefore be a therapeutic target, requires further study.
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