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MGMT assessment in pituitary adenomas: comparison of different immunohistochemistry fixation chemicals

PURPOSE: Despite the established role of O6-methyl-guanine-DNA methyltransferase (MGMT) as a marker for temozolomide response, consensus of the most reliable method to assess MGMT expression in pituitary adenomas is still missing. Currently, immunohistochemistry (IHC) assessment of formaldehyde fixe...

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Autores principales: Micko, Alexander S. G., Höftberger, Romana, Wöhrer, Adelheid, Millesi, Matthias, Knosp, Engelbert, Wolfsberger, Stefan
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer US 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5942339/
https://www.ncbi.nlm.nih.gov/pubmed/29344904
http://dx.doi.org/10.1007/s11102-018-0862-x
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author Micko, Alexander S. G.
Höftberger, Romana
Wöhrer, Adelheid
Millesi, Matthias
Knosp, Engelbert
Wolfsberger, Stefan
author_facet Micko, Alexander S. G.
Höftberger, Romana
Wöhrer, Adelheid
Millesi, Matthias
Knosp, Engelbert
Wolfsberger, Stefan
author_sort Micko, Alexander S. G.
collection PubMed
description PURPOSE: Despite the established role of O6-methyl-guanine-DNA methyltransferase (MGMT) as a marker for temozolomide response, consensus of the most reliable method to assess MGMT expression in pituitary adenomas is still missing. Currently, immunohistochemistry (IHC) assessment of formaldehyde fixed tissue samples is most widely used in a semiquantitative description. As formaldehyde fails to completely preserve nucleic acids, RCL2, an alcohol-based formaldehyde-free fixative, has been proposed as a more reliable alternative in terms of cell stability. Furthermore, as the current method of IHC is semiquantitative and observer-dependent, pyrosequencing, an objective tool to evaluate the methylation status of the MGMT promoter, has emerged as a reliable and accurate alternative. The aim of this study was to validate the current IHC method for assessment of MGMT protein expression in pituitary adenomas. METHODS: The tissue samples of 8 macroadenomas with positive IHC MGMT expression (> 50%) were investigated: first, we compared the time dependent stability of MGMT protein expression after pituitary adenoma removal between formaldehyde vs. RCL2. Then, we compared positive IHC MGMT expression with methylated promoter status using pyrosequencing. RESULTS: In the first 12 h after adenoma removal, tissue samples remained MGMT positive in significantly more samples when fixated with formaldehyde than with RCL2, respectively (96 vs. 81%, p = 0.025). CONCLUSION: Our data confirm that the current method using formaldehyde tissue fixation and IHC reveals stable and reliable results of MGMT assessment in pituitary adenomas.
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spelling pubmed-59423392018-05-14 MGMT assessment in pituitary adenomas: comparison of different immunohistochemistry fixation chemicals Micko, Alexander S. G. Höftberger, Romana Wöhrer, Adelheid Millesi, Matthias Knosp, Engelbert Wolfsberger, Stefan Pituitary Article PURPOSE: Despite the established role of O6-methyl-guanine-DNA methyltransferase (MGMT) as a marker for temozolomide response, consensus of the most reliable method to assess MGMT expression in pituitary adenomas is still missing. Currently, immunohistochemistry (IHC) assessment of formaldehyde fixed tissue samples is most widely used in a semiquantitative description. As formaldehyde fails to completely preserve nucleic acids, RCL2, an alcohol-based formaldehyde-free fixative, has been proposed as a more reliable alternative in terms of cell stability. Furthermore, as the current method of IHC is semiquantitative and observer-dependent, pyrosequencing, an objective tool to evaluate the methylation status of the MGMT promoter, has emerged as a reliable and accurate alternative. The aim of this study was to validate the current IHC method for assessment of MGMT protein expression in pituitary adenomas. METHODS: The tissue samples of 8 macroadenomas with positive IHC MGMT expression (> 50%) were investigated: first, we compared the time dependent stability of MGMT protein expression after pituitary adenoma removal between formaldehyde vs. RCL2. Then, we compared positive IHC MGMT expression with methylated promoter status using pyrosequencing. RESULTS: In the first 12 h after adenoma removal, tissue samples remained MGMT positive in significantly more samples when fixated with formaldehyde than with RCL2, respectively (96 vs. 81%, p = 0.025). CONCLUSION: Our data confirm that the current method using formaldehyde tissue fixation and IHC reveals stable and reliable results of MGMT assessment in pituitary adenomas. Springer US 2018-01-17 2018 /pmc/articles/PMC5942339/ /pubmed/29344904 http://dx.doi.org/10.1007/s11102-018-0862-x Text en © The Author(s) 2018 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
spellingShingle Article
Micko, Alexander S. G.
Höftberger, Romana
Wöhrer, Adelheid
Millesi, Matthias
Knosp, Engelbert
Wolfsberger, Stefan
MGMT assessment in pituitary adenomas: comparison of different immunohistochemistry fixation chemicals
title MGMT assessment in pituitary adenomas: comparison of different immunohistochemistry fixation chemicals
title_full MGMT assessment in pituitary adenomas: comparison of different immunohistochemistry fixation chemicals
title_fullStr MGMT assessment in pituitary adenomas: comparison of different immunohistochemistry fixation chemicals
title_full_unstemmed MGMT assessment in pituitary adenomas: comparison of different immunohistochemistry fixation chemicals
title_short MGMT assessment in pituitary adenomas: comparison of different immunohistochemistry fixation chemicals
title_sort mgmt assessment in pituitary adenomas: comparison of different immunohistochemistry fixation chemicals
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5942339/
https://www.ncbi.nlm.nih.gov/pubmed/29344904
http://dx.doi.org/10.1007/s11102-018-0862-x
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