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PSAT176 Molecular Analysis of AMBRA1 as a Candidate Tumor Suppressor in Sporadic Parathyroid Adenomas

Primary hyperparathyroidism is a common endocrine disorder that is most often caused by a sporadic single-gland parathyroid adenoma. Currently, the only known and experimentally validated oncoprotein for parathyroid adenomas is cyclin D1. The overexpression of cyclin D1 protein has been reported in...

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Autores principales: Arnold, Andrew, Costa-Guda, Jessica, Chinwo, Stephanie, Bellizzi, Justin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9624822/
http://dx.doi.org/10.1210/jendso/bvac150.413
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author Arnold, Andrew
Costa-Guda, Jessica
Chinwo, Stephanie
Bellizzi, Justin
author_facet Arnold, Andrew
Costa-Guda, Jessica
Chinwo, Stephanie
Bellizzi, Justin
author_sort Arnold, Andrew
collection PubMed
description Primary hyperparathyroidism is a common endocrine disorder that is most often caused by a sporadic single-gland parathyroid adenoma. Currently, the only known and experimentally validated oncoprotein for parathyroid adenomas is cyclin D1. The overexpression of cyclin D1 protein has been reported in twenty to forty percent of cases. Eight percent of this overexpression can be explained by DNA rearrangement involving the cyclin D1 locus. The remaining molecular mechanisms behind this overexpression have yet to be identified. In this study, we explored a potential parathyroid tumorigenic mechanism that could increase cyclin D1 stability through a defect in the AMBRA1 E3 ligase adaptor, a molecule responsible for its degradation. Evidence that AMBRA1 may be a tumor suppressor gene includes the accumulation of cyclin D with hyperproliferation in AMBRA1-deficient cells, the context-dependent growth of tumors in Ambra1-deficient mice, and the finding that low levels of AMBRA1 correlated with poor clinical outcomes in The Cancer Genome Atlas (TCGA). We have therefore proceeded examine AMBRA1 for evidence of tumor suppressor-type inactivation within a cohort of parathyroid adenomas. Genomic DNA from twenty-six typical sporadic parathyroid adenomas was subjected to PCR-amplification of all eighteen coding exons of AMBRA1, followed by Sanger sequencing. Sequences were analyzed by comparison to the normal reference sequence, seeking to assess any observed intragenic or splice-site variants as potential or likely loss-of-function mutations. Thus far, with ninety-seven percent of the coding region fully sequenced, no intragenic AMBRA1 inactivating mutations were observed. Three known single nucleotide polymorphisms, considered non-pathogenic, were identified: missense variant c.3028G>T, and 3' UTR variants c.*491T>C and c.*576A>T, each in a single tumor. Future study of increased numbers of parathyroid adenomas is needed to exclude the possibility that AMBRA1 inactivation could play a driver role in a small percentage of cases, and the possibility that AMBRA1 might contribute less directly e.g. via secondarily altered expression also warrants investigation. Nonetheless, our current observations strongly suggest that AMBRA1 does not have a frequent role as a classic 2-hit tumor suppressor gene in sporadic parathyroid adenomas. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.
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spelling pubmed-96248222022-11-14 PSAT176 Molecular Analysis of AMBRA1 as a Candidate Tumor Suppressor in Sporadic Parathyroid Adenomas Arnold, Andrew Costa-Guda, Jessica Chinwo, Stephanie Bellizzi, Justin J Endocr Soc Bone & Mineral Metabolism Primary hyperparathyroidism is a common endocrine disorder that is most often caused by a sporadic single-gland parathyroid adenoma. Currently, the only known and experimentally validated oncoprotein for parathyroid adenomas is cyclin D1. The overexpression of cyclin D1 protein has been reported in twenty to forty percent of cases. Eight percent of this overexpression can be explained by DNA rearrangement involving the cyclin D1 locus. The remaining molecular mechanisms behind this overexpression have yet to be identified. In this study, we explored a potential parathyroid tumorigenic mechanism that could increase cyclin D1 stability through a defect in the AMBRA1 E3 ligase adaptor, a molecule responsible for its degradation. Evidence that AMBRA1 may be a tumor suppressor gene includes the accumulation of cyclin D with hyperproliferation in AMBRA1-deficient cells, the context-dependent growth of tumors in Ambra1-deficient mice, and the finding that low levels of AMBRA1 correlated with poor clinical outcomes in The Cancer Genome Atlas (TCGA). We have therefore proceeded examine AMBRA1 for evidence of tumor suppressor-type inactivation within a cohort of parathyroid adenomas. Genomic DNA from twenty-six typical sporadic parathyroid adenomas was subjected to PCR-amplification of all eighteen coding exons of AMBRA1, followed by Sanger sequencing. Sequences were analyzed by comparison to the normal reference sequence, seeking to assess any observed intragenic or splice-site variants as potential or likely loss-of-function mutations. Thus far, with ninety-seven percent of the coding region fully sequenced, no intragenic AMBRA1 inactivating mutations were observed. Three known single nucleotide polymorphisms, considered non-pathogenic, were identified: missense variant c.3028G>T, and 3' UTR variants c.*491T>C and c.*576A>T, each in a single tumor. Future study of increased numbers of parathyroid adenomas is needed to exclude the possibility that AMBRA1 inactivation could play a driver role in a small percentage of cases, and the possibility that AMBRA1 might contribute less directly e.g. via secondarily altered expression also warrants investigation. Nonetheless, our current observations strongly suggest that AMBRA1 does not have a frequent role as a classic 2-hit tumor suppressor gene in sporadic parathyroid adenomas. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m. Oxford University Press 2022-11-01 /pmc/articles/PMC9624822/ http://dx.doi.org/10.1210/jendso/bvac150.413 Text en © The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society. https://creativecommons.org/licenses/by-nc-nd/4.0/This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs licence (https://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reproduction and distribution of the work, in any medium, provided the original work is not altered or transformed in any way, and that the work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
spellingShingle Bone & Mineral Metabolism
Arnold, Andrew
Costa-Guda, Jessica
Chinwo, Stephanie
Bellizzi, Justin
PSAT176 Molecular Analysis of AMBRA1 as a Candidate Tumor Suppressor in Sporadic Parathyroid Adenomas
title PSAT176 Molecular Analysis of AMBRA1 as a Candidate Tumor Suppressor in Sporadic Parathyroid Adenomas
title_full PSAT176 Molecular Analysis of AMBRA1 as a Candidate Tumor Suppressor in Sporadic Parathyroid Adenomas
title_fullStr PSAT176 Molecular Analysis of AMBRA1 as a Candidate Tumor Suppressor in Sporadic Parathyroid Adenomas
title_full_unstemmed PSAT176 Molecular Analysis of AMBRA1 as a Candidate Tumor Suppressor in Sporadic Parathyroid Adenomas
title_short PSAT176 Molecular Analysis of AMBRA1 as a Candidate Tumor Suppressor in Sporadic Parathyroid Adenomas
title_sort psat176 molecular analysis of ambra1 as a candidate tumor suppressor in sporadic parathyroid adenomas
topic Bone & Mineral Metabolism
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9624822/
http://dx.doi.org/10.1210/jendso/bvac150.413
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